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π¬ TOPIC 1: WHAT IS NUCLEAR MEDICINE?
π¬ TOPIC 1: WHAT IS NUCLEAR MEDICINE?
π· Definition and Overview
π· Definition and Overview
Nuclear medicine is a specialized field of medicine that uses small amounts of radioactive substances to diagnose and treat diseases. These substances are called radiotracers or radiopharmaceuticals.
What makes nuclear medicine unique is that it provides functional or metabolic informationβnot just anatomical images. This means it shows how organs or tissues are working, not just how they look.
π· How It Works β Step-by-Step
π· How It Works β Step-by-Step
Preparation of the Radiopharmaceutical (Radiotracer):
A radioactive isotope is attached (or bound) to a compound that targets a specific organ, tissue, or cellular function.
This combination is called a radiopharmaceutical.
Administration to the Patient:
The radiopharmaceutical is introduced into the patientβs body using various routes:
Intravenous (IV) injection β most common.
Orally β swallowed.
Inhalation β breathed in through the lungs.
Circulation and Targeting:
The radiotracer circulates through the body, naturally targeting the organ or process of interest (e.g. bones, thyroid, heart).
Once it accumulates in the target area, it emits small amounts of radiation.
Image Capture:
This radiation is detected by a specialized imaging machine, usually a gamma camera.
The gamma camera collects the radiation signals and creates an image called a scintigram.
This image shows how well the organ is functioning, or where there might be abnormalities like tumors, blockages, or infection.
Interpretation and Reporting:
The images and data are processed using computers.
A trained nuclear medicine physician interprets the results.
A final written report is sent to the doctor who requested the scan.
π· Advantages of Nuclear Medicine
π· Advantages of Nuclear Medicine
Functional Imaging: Shows how tissues are working, not just their shape.
Early Detection: Detects disease processes before structural changes are visible on X-rays or CT scans.
Whole-body Evaluation: Many scans (like bone scans or PET) evaluate the entire body at once.
Minimal Side Effects: Extremely low risk of allergic reactions or complications.
Quantitative Measurements: Provides numerical data (e.g. how well kidneys or heart are functioning).
π· What Patients Should Expect
π· What Patients Should Expect
Imaging may take 10 to 60 minutes, depending on the test.
Some procedures require the patient to lie completely still.
Patients who suffer from claustrophobia (fear of enclosed spaces) should inform the doctor or technician beforehand for proper counseling.
In some cases, blood samples may need to be drawn before or after the scan.
π· Safety of Nuclear Medicine Procedures
π· Safety of Nuclear Medicine Procedures
Nuclear medicine scans are very safe.
The amount of radiation used is comparable to or lower than traditional imaging methods like:
X-rays,
CT scans.
There is no pharmacological effect from the radiotracers because the amounts used are tiny.
Long-term side effects are extremely rare β nuclear medicine has been safely used for over 50 years.
Nuclear medicine scans are generally not recommended for pregnant women, unless the benefits outweigh the risks.
π· Responsibilities of the Referring Physician
π· Responsibilities of the Referring Physician
For an accurate diagnosis and safe procedure, the referring doctor (e.g. general practitioner or specialist who requests the scan) should:
Complete the nuclear medicine request form in full (where applicable).
Provide full clinical information, including:
The patientβs diagnosis or suspected condition.
Any relevant symptoms or findings.
All current medications the patient is taking.
Previous imaging reports (X-rays, CT, MRI).
Be aware of what nuclear medicine services are available in the country or local facility.
πΈ Equipment Used
πΈ Equipment Used
Gamma Camera: This is the main imaging device that captures the radiation signals from the radiotracer inside the patientβs body and creates the image.
: In the document, there is a figure (FIG. 1) showing a patient being imaged with a gamma camera.
β
Summary Table
β
Summary Table
Concept
Explanation
Radiopharmaceutical
A radioactive substance attached to a compound that targets a specific organ.
Administration
Usually by IV injection, but can also be oral or inhaled.
Scintigram
The image produced by detecting radiation from the body using a gamma camera.
Safety
Very safe; radiation exposure is minimal and short-lived.
Use
For diagnosis (e.g. cancer, heart disease, thyroid issues) and treatment (e.g. thyroid cancer).
π« Contraindications (When to Avoid)
π« Contraindications (When to Avoid)
Pregnancy: Most nuclear medicine procedures are avoided during pregnancy unless absolutely necessary.
Breastfeeding: May need to be paused depending on the radiotracer usedβconsult the nuclear medicine physician.
𦴠TOPIC 2: Oncology β Bone Scintigraphy
𦴠TOPIC 2: Oncology β Bone Scintigraphy
π· Definition and Purpose
π· Definition and Purpose
Bone scintigraphy, also called a bone scan, is a nuclear medicine imaging technique used to evaluate the metabolic activity of the entire skeleton. It is especially useful for detecting:
Cancer spread to bones (metastases),
Bone infections or inflammation,
Fractures not visible on X-rays,
Other bone-related conditions.
It is highly sensitive, meaning it can detect very early changes in bone metabolism, even before structural changes appear on X-rays or CT scans.
π· How Bone Scintigraphy Works
π· How Bone Scintigraphy Works
A radiopharmaceutical, typically Technetium-99m-labeled diphosphonates, is injected intravenously.
This compound binds to bone and accumulates more in areas of increased osteoblastic activity (bone-forming activity).
The radiotracer emits gamma radiation, which is captured using a gamma camera to create a whole-body image.
The resulting image shows:
βHot spotsβ β areas of increased tracer uptake, indicating high bone turnover, e.g. cancer metastasis or inflammation.
βCold spotsβ β areas of decreased uptake, which may indicate poor blood supply, infarcts, or bone destruction, such as in certain tumors.
π· Clinical Indications
π· Clinical Indications
πΉ Oncological Indications (Cancer-related)
Bone scintigraphy is commonly used to detect or assess:
Early detection of bone metastases in patients with:
Breast cancer,
Prostate cancer, and
Other cancers that spread to bone.
(e.g. Fig. 3 in the pamphlet shows skeletal metastases)
Primary bone tumors, such as:
Osteogenic sarcoma (Fig. 4 shows a case with metastasis to the lung and bones)
Benign bone tumors (to evaluate activity)
Pre-treatment assessment before giving radionuclide therapy for bone pain (palliative care in metastatic cancer)
πΉ Non-Oncological Indications
Bone scans are also valuable for detecting:
β Infections and Inflammation
Osteomyelitis (bone infection)
Septic arthritis
Diabetic foot infection (to determine bone vs soft tissue involvement)
Prosthesis-related infections
β Trauma
Stress fractures
Fractures not seen clearly on X-ray
Possible child abuse (multiple fractures of different ages)
β Vascular Conditions
Avascular necrosis (AVN) β loss of blood supply to the bone, especially femoral head (e.g. in sickle cell disease)
(e.g. Fig. 5 shows decreased uptake in femoral head)
β Other Bone Disorders
Pagetβs disease
Unexplained bone pain
Hypercalcaemia of unknown cause
Reflex sympathetic dystrophy
Arthritic changes
Maturity of heterotopic ossification (bone growth in soft tissue)
π· Patient Preparation
π· Patient Preparation
Adequate hydration is essential:
Patients must drink lots of water before and after the scan to help flush out the tracer from the body.
Bring previous X-rays/CT scans if available:
This helps the nuclear medicine physician interpret the scan better.
π· Interfering Medications
π· Interfering Medications
Phosphonates (used to treat osteoporosis or bone metastases) can interfere with the scan and may need to be stopped before imaging.
π· Procedure β Step by Step
π· Procedure β Step by Step
Consultation with nuclear medicine physician.
IV injection of the radiopharmaceutical.
Waiting period of 2β4 hours to allow the tracer to accumulate in the bones.
During this time:
Patient can leave the department temporarily.
Must drink water frequently and urinate often to reduce background noise from the tracer in the bladder.
Imaging session:
Duration: 30β45 minutes for standard scans.
In some cases, initial scans may be done at injection time, followed by delayed images at 2β4 hours.
Total time commitment: about 4β5 hours in total.
π· Safety and Side Effects
π· Safety and Side Effects
Side effects are extremely rare.
The tracer dose is very small and not harmful.
Patients are not radioactive to others, so no isolation is needed.
However:
Pregnancy is a contraindication β do not perform bone scans during pregnancy.
Breastfeeding should be paused β consult the nuclear medicine doctor for advice.
πΈ Summary Table
πΈ Summary Table
Section
Details
Purpose
Detect bone metastases, infections, fractures, and more
Tracer
Technetium-99m labeled diphosphonates
Imaging Time
30β45 minutes (after 2β4 hour delay)
Preparation
Drink water, bring prior scans
Safety
Very safe; avoid in pregnancy
Hot Spots
Increased tracer uptake (e.g. metastasis)
Cold Spots
Decreased uptake (e.g. AVN, infarcts)
π§ Tona
π§ Tona
Bone scintigraphy is a powerful, whole-body, highly sensitive test that detects early changes in bone metabolism. It plays a vital role in cancer staging, identifying infections, and evaluating unexplained bone pain. It is safe, easy to perform, and invaluable for both oncological and non-oncological conditions.
𧬠TOPIC 3: Iodine-131 Ablation of Thyroid Remnants
𧬠TOPIC 3: Iodine-131 Ablation of Thyroid Remnants
π· Background
π· Background
After thyroidectomy (surgical removal of the thyroid gland), some small portions of thyroid tissue (called thyroid remnants) may remain in the neck. In patients with follicular or papillary thyroid cancer, it's important to destroy these remnants because:
They may harbor residual cancer cells.
Eliminating them improves disease control and long-term survival.
It allows thyroglobulin (a protein made by thyroid tissue) to become a sensitive tumor marker β meaning even small recurrences or metastases can be monitored by measuring thyroglobulin levels.
This process is called radioiodine ablation, and it uses a radioactive isotope of iodine: Iodine-131 (ΒΉΒ³ΒΉI).
π· Why ΒΉΒ³ΒΉI Is Used
π· Why ΒΉΒ³ΒΉI Is Used
The thyroid naturally absorbs iodine.
ΒΉΒ³ΒΉI delivers localized radiation to thyroid tissue, destroying it without harming surrounding tissues.
Itβs especially effective for differentiated thyroid cancers (papillary and follicular).
β Note: This treatment is not useful for medullary thyroid cancer, because that type of cancer does not absorb iodine.
π· Indications for Iodine-131 Ablation
π· Indications for Iodine-131 Ablation
Patients who have had thyroidectomy for:
Papillary thyroid carcinoma.
Follicular thyroid carcinoma.
Any T stage (tumor size and spread) may benefit, especially stage 1b and above.
β Improves:
Local recurrence rates.
Distant metastasis control.
Overall survival.
π· Patient Preparation
π· Patient Preparation
To make the thyroid remnants absorb the radioactive iodine effectively, the patient must be in a hypothyroid state β meaning there must be high levels of TSH (thyroid-stimulating hormone) in the blood.
πΉ If the patient is not yet on thyroxine (T4):
Best to perform the ablation 4β6 weeks after surgery, before starting thyroid hormone therapy.
πΉ If the patient is already on thyroxine (T4):
Stop thyroxine for 4β6 weeks before ablation.
This allows TSH levels to rise above 30 mIU/L, which is needed for optimal ΒΉΒ³ΒΉI uptake.
π· Interfering Medications or Substances
π· Interfering Medications or Substances
Certain drugs and substances interfere with iodine uptake:
Type
Examples
Thyroid hormone therapy
T4 (levothyroxine), T3 (liothyronine)
Iodine-containing substances
Iodine-rich foods, multivitamins, amiodarone, CT contrast media
Thyrostatic drugs
Propylthiouracil, carbimazole, methimazole
β οΈ IMPORTANT WARNING:
If the patient has had a CT scan with iodine contrast, the ΒΉΒ³ΒΉI therapy must be delayed for at least 6 months. Otherwise, the radioactive iodine will not be taken up by the thyroid remnants.
π· How the Treatment is Given
π· How the Treatment is Given
Patient must fast for 6β12 hours before the treatment.
A capsule or liquid form of ΒΉΒ³ΒΉI is administered orally with some water.
Depending on local radiation safety laws, the patient may be:
Treated as an outpatient, OR
Admitted to an isolation ward for a few days to protect others from radiation exposure.
π Dose range: 50β100 mCi (1.8β3.7 GBq)
π· Potential Side Effects
π· Potential Side Effects
Most patients experience no side effects.
Rarely, there may be mild neck discomfort or pain over the thyroid bed (due to inflammation).
Very rarely, nausea, dry mouth, or taste changes may occur.
π· Follow-up and Evaluation
π· Follow-up and Evaluation
A follow-up scan is usually done 3β6 months after ablation to check if all remnants were destroyed.
Blood tests for thyroglobulin and TSH are used to monitor for recurrence.
π§ Key Points to Remember
π§ Key Points to Remember
Topic
Summary
Used for
Ablating thyroid remnants post-thyroidectomy in papillary or follicular thyroid cancer
Not used for
Medullary thyroid cancer
Best time
4β6 weeks after surgery, before starting thyroxine
TSH target
>30 mIU/L
Dose
50β100 mCi (oral)
Prep
Fasting 6β12 h; stop thyroxine and avoid iodine-rich substances
Safety
Highly effective and well-tolerated
β Contraindications
β Contraindications
Pregnancy: Absolutely contraindicated β must confirm patient is not pregnant.
Breastfeeding: Must be interrupted before treatment β consult the nuclear medicine physician for timing.
Close contact with others (especially children and pregnant women) should be minimized after therapy.
β’οΈ TOPIC 4: Radionuclide Therapy
β’οΈ TOPIC 4: Radionuclide Therapy
π· Overview
π· Overview
Radionuclide therapy is a branch of nuclear medicine where radioactive substances are used not just for imaging, but to treat specific medical conditionsβmost commonly certain cancers and bone pain.
These therapies work by delivering targeted radiation directly to diseased tissues (like tumors or inflamed bone), with minimal damage to surrounding healthy tissue.
The radioactive materials used in therapy are often called therapeutic radiopharmaceuticals.
π· Most Common Use: Iodine-131 (ΒΉΒ³ΒΉI)
π· Most Common Use: Iodine-131 (ΒΉΒ³ΒΉI)
The most widely known radionuclide therapy is ΒΉΒ³ΒΉI for treating:
Benign thyroid conditions like Gravesβ disease and toxic nodules.
Malignant thyroid conditions such as thyroid cancer remnants and metastases (covered in previous topic).
But radionuclide therapy includes much more than just iodine.
π· Other Clinical Applications of Radionuclide Therapy
π· Other Clinical Applications of Radionuclide Therapy
Phaeochromocytoma and Neuroblastoma:
These are rare tumors that arise from adrenal or nerve tissues.
Treated using a compound called metaiodobenzylguanidine (MIBG) labeled with ΒΉΒ³ΒΉI.
MIBG is taken up by neuroendocrine cells, allowing targeted radiation therapy.
Neuroendocrine Tumors (Carcinoids):
These slow-growing tumors can arise in the lungs, GI tract, or pancreas.
Treated with Indium-111-labeled octreotide, which binds to somatostatin receptors on tumor cells.
Delivers radiation directly to tumor sites.
Palliative Therapy for Bone Metastases:
Patients with painful skeletal metastases, especially from breast or prostate cancer, may benefit.
Radionuclides like Samarium-153 (ΒΉβ΅Β³Sm-EDTMP) and Strontium-89 (βΈβΉSr) are used.
These compounds seek out areas of high bone turnover, such as metastatic lesions, and deliver targeted pain relief.
Advanced B-cell Lymphoma:
For cases that do not respond to chemotherapy, a specialized therapy called radioimmunotherapy is available.
A monoclonal antibody (e.g. ibritumomab) is combined with a radioactive isotope like Yttrium-90 (βΉβ°Y).
The antibody targets CD20 receptors on B-cells, delivering focused radiation and destroying malignant cells.
An example of this drug is Zevalin (βΉβ°Y-ibritumomab tiuxetan).
π· Why Radionuclide Therapy is Effective
π· Why Radionuclide Therapy is Effective
These therapies are selective, meaning they go directly to the disease site.
Unlike external beam radiation (which can affect large areas), radionuclide therapy targets the disease from inside the body.
It is often used when:
Surgery is not possible.
Cancer has spread widely.
Other treatments have failed.
π· Patient Considerations and Preparation
π· Patient Considerations and Preparation
Consultation with a nuclear medicine specialist is always needed to determine if radionuclide therapy is appropriate.
Informed consent and counseling are crucial, as these are systemic therapies involving radiation.
Prior imaging (e.g. scans, blood tests, and staging studies) is required to confirm that the disease will take up the specific radiopharmaceutical.
Patients must follow specific preparation guidelines, which vary depending on the type of therapy:
For example, avoiding certain medications, stopping thyroid hormones, or undergoing dietary restrictions.
π· Side Effects and Safety
π· Side Effects and Safety
Side effects are generally mild and well tolerated.
They vary depending on the type of radionuclide and the patient's overall health.
Possible side effects may include:
Temporary fatigue.
Mild pain flare in case of bone metastases.
Very rarely, suppression of bone marrow function.
Patients may need to follow radiation safety precautions for a few days to limit exposure to family members.
π· Follow-Up and Monitoring
π· Follow-Up and Monitoring
Patients are monitored through:
Repeat scans.
Tumor markers.
Blood tests.
Clinical symptoms.
In many cases, therapy can be repeated if needed.
Long-term follow-up is necessary, especially for therapies involving bone marrow or systemic cancers.
π· Tona
π· Tona
Radionuclide therapy is a powerful treatment option that extends beyond thyroid disease. It offers targeted, low-toxicity radiation to treat neuroendocrine tumors, metastatic bone pain, and resistant lymphomas. When used properly, it improves symptom control, enhances quality of life, and may even contribute to cancer remission. It's a critical part of modern nuclear medicine.
𦡠TOPIC 5: Orthopaedic Applications of Bone Scans
𦡠TOPIC 5: Orthopaedic Applications of Bone Scans
π· Overview
π· Overview
In addition to cancer diagnosis, bone scintigraphy (bone scans) plays an important role in orthopaedic medicine. This includes identifying:
Infections in bones or joints,
Inflammation,
Fractures,
Prosthesis complications, and
Other non-malignant skeletal disorders.
It is a highly sensitive imaging tool that detects abnormal bone metabolism, often before structural damage is visible on X-rays.
π· What the Bone Scan Detects in Orthopaedics
π· What the Bone Scan Detects in Orthopaedics
Bone scans identify areas of increased osteoblastic activity (bone-forming response) or increased blood flow, both of which are hallmarks of:
Inflammation,
Infection,
Trauma,
Mechanical stress, and
Degenerative changes.
This allows early detection of:
Stress injuries,
Post-operative complications, and
Hidden fractures.
π· Common Orthopaedic Indications
π· Common Orthopaedic Indications
Hereβs how bone scintigraphy supports orthopaedic diagnosis and care:
πΉ Infections
Osteomyelitis: infection of the bone itself.
Septic arthritis: infection inside the joint space.
Diabetic foot complications: helps differentiate between soft tissue and bone involvement.
Infections around prosthetic joints.
πΉ Prosthesis Complications
Bone scans can help identify the cause of persistent joint pain after joint replacement surgery (e.g. hip or knee prosthesis).
Helps to distinguish between:
Infection,
Loosening of the prosthesis, or
Normal post-operative remodeling.
πΉ Fractures
Detection of stress fractures or occult fractures (those not visible on regular X-rays).
Used when trauma is suspected but not confirmed radiographically.
Also used in cases of suspected child abuse, where old and new fractures may be detected across the skeleton.
πΉ Avascular Necrosis (AVN)
Bone scans can detect early stages of avascular necrosis, where bone tissue dies due to lack of blood supply.
Common sites include:
Head of femur,
Talus (ankle bone),
Scaphoid (wrist bone).
Especially useful in conditions like sickle cell disease, where bone infarcts are common.
πΉ Other Conditions
Pagetβs disease of bone: a chronic disorder with abnormal bone remodeling.
Hypercalcemia of unknown cause: to look for bone involvement.
Reflex sympathetic dystrophy (Complex Regional Pain Syndrome): areas of pain and swelling with unclear origin.
Evaluation of unexplained bone pain: when other tests are inconclusive.
Heterotopic ossification: monitoring the development and maturity of abnormal bone growth in soft tissues (e.g. after spinal cord injury or surgery).
Arthritic bone conditions: to assess the severity and activity of arthritis.
π· Why Itβs Important
π· Why Itβs Important
Orthopaedic bone scans are particularly useful when:
X-rays are inconclusive.
A whole-body overview is needed.
Differentiation between infection, inflammation, or mechanical failure is necessary.
Assessing the extent of a disease (e.g. multifocal osteomyelitis or widespread arthritis).
π· What the Scan Involves
π· What the Scan Involves
The patient is injected with a radiotracer (usually technetium-99m labeled compound).
Imaging is performed after a delay (usually 2β4 hours post-injection), to allow the tracer to accumulate in the bones.
In some cases, immediate images may be taken at the time of injection to evaluate blood flow to the area (especially in suspected infection or inflammation).
Patients are encouraged to drink fluids and urinate frequently to help eliminate excess tracer and improve image quality.
π· Safety and Side Effects
π· Safety and Side Effects
The procedure is safe and well-tolerated.
Side effects are very rare.
Radiation exposure is minimal and similar to other diagnostic imaging techniques.
As with other nuclear medicine procedures:
Pregnancy is a contraindication.
Breastfeeding may need to be paused; consult with the nuclear medicine physician.
π· Tona
π· Tona
Bone scans are not just for detecting cancer; they are a critical diagnostic tool in orthopaedics, helping to evaluate infections, inflammation, trauma, prosthetic issues, and various non-cancerous bone disorders. They are especially valuable when other imaging methods fail to give clear answers and can guide both diagnosis and treatment planning.
β€οΈ TOPIC 6: Cardiology β Myocardial Perfusion Imaging (MPI)
β€οΈ TOPIC 6: Cardiology β Myocardial Perfusion Imaging (MPI)
π· Overview
π· Overview
Myocardial perfusion imaging (MPI) is a non-invasive nuclear medicine technique used to assess blood flow to the heart muscle. It provides vital information about:
Regional myocardial perfusion (blood supply to different parts of the heart),
Wall motion of the heart,
Overall pumping function (ejection fraction).
MPI is especially helpful in detecting coronary artery disease (CAD), which is the narrowing or blockage of the blood vessels that supply the heart.
π· Why Itβs Done
π· Why Itβs Done
Myocardial perfusion imaging is used in both diagnosis and management of patients with or without known heart disease. It helps in:
Diagnosing Ischaemia (poor blood flow):
Useful in patients with chest pain, especially when other tests (like ECG) are unclear.
Can detect areas of the heart muscle that arenβt receiving enough blood during stress or exercise.
Assessing Known Heart Disease:
Evaluates how severe the disease is.
Identifies which areas are affected.
Assesses whether angioplasty or bypass surgery might be needed.
Monitoring After a Heart Attack:
Determines if viable (living) heart tissue remains.
Helps stratify future cardiac risk.
Pre-Surgical Risk Assessment:
Performed in patients with high risk of cardiac events prior to undergoing non-cardiac surgery (e.g. diabetic patients or those with previous heart problems).
Special Groups:
Patients with diabetes, family history of heart disease, or atypical symptoms benefit from early detection of silent ischaemia.
π· How It Works
π· How It Works
A radiopharmaceutical (typically technetium-99m or thallium-201) is injected into the patient.
This tracer is taken up by healthy heart muscle cells that have adequate blood flow.
Areas of the heart with reduced uptake indicate reduced perfusion (possible ischaemia or scar tissue).
Images are captured using a gamma camera and processed to form 3D views of the heart at rest and under stress.
Stress can be induced in two ways:
Exercise (treadmill or bicycle),
Pharmacological agents (e.g. adenosine or dipyridamole) for patients who canβt exercise.
π· Patient Preparation
π· Patient Preparation
To ensure reliable and accurate results, patients must follow these instructions:
Eat a light breakfast only, and avoid fatty meals.
No coffee, tea, chocolate, or any caffeine-containing products for at least 24 hours before the test.
Stop certain cardiac medications:
Beta-blockers may reduce the heartβs response to exercise stress.
Bronchodilators may interfere with pharmacological stress (especially in asthma or COPD patients).
Patients should consult with the nuclear medicine team or their referring physician for specific medication instructions.
π· How the Procedure Is Performed
π· How the Procedure Is Performed
An intravenous line (IV) is placed.
Monitoring of ECG and blood pressure is done throughout the test.
The patient performs exercise (or is given a stress-inducing drug).
The radiotracer is injected at peak stress.
After a short wait, images are captured.
In many cases, a second scan at rest is also done (either the same day or on a separate day).
This helps compare blood flow during stress vs rest and identify areas of reversible ischaemia or permanent damage.
π· What the Images Show
π· What the Images Show
Normal scan: Uniform tracer uptake at rest and stress.
Ischaemia: Decreased uptake during stress, but normal at rest (reversible).
Infarction (scar): Decreased uptake both at rest and stress (non-reversible).
Mixed pattern: Indicates both scarred and viable tissue.
π· Side Effects and Risks
π· Side Effects and Risks
Exercise stress may cause:
Chest pain,
Dizziness,
Shortness of breath,
Fatigue.
Pharmacologic stress (dipyridamole, adenosine) may cause:
Headache,
Flushing,
Nausea,
Mild chest discomfort.
These side effects are typically short-lived and well managed during the test.
π· Additional Notes
π· Additional Notes
The full test (including rest and stress phases) may take up to 4β6 hours.
If done in two parts, the patient may return for the rest scan on another day.
Patients should plan to be off work for a full day.
Pregnancy is a contraindication β always confirm pregnancy status before proceeding.
Breastfeeding mothers should consult the nuclear medicine physician. Usually, breastfeeding does not need to be interrupted, but this depends on the tracer used.
Patients should bring previous cardiac tests, such as:
ECGs,
Echocardiograms,
Stress test results,
Angiography reports.
π· Tona
π· Tona
Myocardial perfusion imaging is a non-invasive, highly informative test used to diagnose and monitor coronary artery disease. It compares the blood flow to the heart muscle during stress and at rest, helping identify reversible ischaemia, heart muscle damage, and guiding decisions on medical or surgical treatment. It is especially helpful in complex or high-risk patients where other tests may not be conclusive.
β€οΈβπ₯ TOPIC 7: Determining Ventricular Pumping Function
β€οΈβπ₯ TOPIC 7: Determining Ventricular Pumping Function
π· Overview
π· Overview
This nuclear medicine procedure is used to assess the pumping ability of the heart, specifically:
The left ventricular (LV) ejection fraction (how well the heart pumps blood out).
Right ventricular (RV) function (in some cases).
Wall motion during the cardiac cycle.
It provides precise and objective data on how well the heart is working, which is essential for managing patients with:
Heart failure,
Cardiomyopathies,
Valvular diseases, and
Those undergoing chemotherapy with cardiotoxic drugs.
π· What the Test Measures
π· What the Test Measures
The test calculates:
Ejection Fraction (EF): The percentage of blood pumped out of the ventricles with each heartbeat.
Normal LV EF is typically 50β70%.
Low EF suggests heart failure or damage.
Wall motion abnormalities: Helps detect areas of poor contraction, scarring, or aneurysm after a heart attack.
This test is also known as:
Gated Blood Pool Imaging, or
Radionuclide Ventriculography (MUGA scan).
π· Clinical Indications
π· Clinical Indications
The test is useful in various cardiac conditions:
Congestive Heart Failure (CHF): To determine the severity and monitor treatment.
Before and during chemotherapy: Especially with drugs like adriamycin (doxorubicin), which can damage the heart muscle.
Valvular heart disease: To monitor how the valves affect heart function.
Post-myocardial infarction: To detect wall motion abnormalities like ventricular aneurysm.
Cardiac transplant evaluation: Helps assess candidacy and post-transplant function.
π· Patient Preparation
π· Patient Preparation
No special preparation is needed.
Patients should inform the physician if they are on heparin or other blood thinners, as these may interfere with red blood cell labeling used in the test.
π· How the Test Is Performed
π· How the Test Is Performed
A small blood sample (5β10 mL) is drawn from the patient.
The red blood cells are tagged with a radioactive tracer (commonly technetium-99m).
The labeled blood is re-injected into the patient.
The patient is connected to ECG monitoring to synchronize the scan with the heartβs rhythm.
The gamma camera captures multiple images of the heart at various points in the cardiac cycle.
The scan typically lasts about 30 minutes.
This technique allows the heart's movement to be recorded frame by frame, like a motion picture, showing how the ventricles contract and relax.
π· How Results Are Interpreted
π· How Results Are Interpreted
Normal scan: The left ventricle shows strong, symmetrical contraction with a normal ejection fraction.
Abnormal scan:
Global dysfunction: Poor contraction throughout (e.g. in dilated cardiomyopathy).
Regional wall motion defects: Localized areas not contracting well (e.g. after heart attack).
No change in ventricle size between diastole and systole suggests severely reduced function.
These images allow clinicians to quantify cardiac performance, not just estimate it.
π· Safety and Side Effects
π· Safety and Side Effects
The procedure is safe and non-invasive.
There are no known side effects from the radiotracer.
No contrast dye is used, so it's safe for patients with kidney problems or contrast allergies.
However:
Pregnancy is a contraindication β pregnant women should not undergo this test.
Breastfeeding mothers are advised to pause breastfeeding temporarily; consultation with the nuclear medicine specialist is required.
π· Time Commitment
π· Time Commitment
The entire process, including blood cell labeling and scanning, takes around 2 hours.
Patients should plan accordingly for that duration.
π· Tona
π· Tona
This procedure offers a precise, objective, and reproducible way to measure how well the heart is pumping. It is essential in monitoring patients with heart failure, cardiotoxic chemotherapy, and valvular disease, as well as in post-heart attack care. It allows doctors to make informed decisions about treatment, medication adjustments, or need for more advanced therapies like transplant.
π¦ TOPIC 8: Endocrinology β Thyroid Imaging
π¦ TOPIC 8: Endocrinology β Thyroid Imaging
π· Overview
π· Overview
Thyroid imaging in nuclear medicine is used to evaluate the function and structure of the thyroid gland using radiotracers that mimic iodine. This technique helps detect:
Hyperactive or underactive thyroid nodules,
Diffuse thyroid disease, and
Ectopic thyroid tissue (thyroid tissue in abnormal locations).
Unlike ultrasound, which shows anatomy, thyroid scintigraphy reveals how the gland works β whether parts of it are overactive, inactive, or normal in function.
π· How It Works
π· How It Works
The thyroid gland naturally concentrates iodine to produce thyroid hormones. Nuclear medicine takes advantage of this by using two main radiotracers:
Technetium-99m pertechnetate (βΉβΉα΅TcOββ»):
Commonly used for routine thyroid scans.
Mimics iodine uptake but is not organified (not converted into hormone).
Iodine-131 (ΒΉΒ³ΒΉI) or Iodine-123 (ΒΉΒ²Β³I):
Used when iodine-based uptake and imaging is needed, especially for therapy planning or dosimetry.
Once the tracer is administered, a gamma camera captures an image of the thyroid, showing uptake distribution and functionality of the gland or nodules.
π· Clinical Indications
π· Clinical Indications
Thyroid scintigraphy is used in various thyroid-related conditions:
Evaluation of Hyperthyroidism
Gravesβ disease: Diffusely enlarged gland with intense uptake.
Toxic multinodular goiter (Plummerβs disease): Multiple "hot" nodules with suppressed normal tissue.
Solitary toxic nodule: One overactive nodule; rest of the gland is suppressed.
Factitious hyperthyroidism: Low uptake from exogenous thyroid hormone or iodine exposure.
Thyroiditis (subacute or silent): Low uptake due to inflammation or hormone leakage.
Drug-induced or iodine-induced thyrotoxicosis.
Characterization of Thyroid Nodules
Helps differentiate:
Hot nodules (hyperfunctioning): Rarely malignant.
Cold nodules (hypofunctioning): Higher risk of malignancy.
Detection of Ectopic Thyroid Tissue
Example sites: base of tongue, thyroglossal duct cyst, mediastinum.
Assessment of Post-Thyroidectomy Remnants
Determines the amount of remaining thyroid tissue after surgery.
Evaluation of Post-Radiation Patients
Identifies functional abnormalities in patients previously exposed to neck radiation.
Organification Defects
Rare congenital disorders in which iodine uptake occurs but cannot be used to make hormone. Diagnosed using a perchlorate discharge test.
π· Patient Preparation
π· Patient Preparation
Proper preparation ensures accurate scan interpretation:
Patients must have recent thyroid function tests:
TSH (thyroid stimulating hormone),
Free T3 (triiodothyronine),
Free T4 (thyroxine).
For iodine-based imaging (e.g., ΒΉΒ³ΒΉI dosimetry):
Overnight fasting is required.
The patient should avoid iodine-containing substances for days to weeks prior.
Pregnancy must be ruled out.
Breastfeeding status must be discussed with the nuclear medicine physician.
π· Interfering Medications/Substances
π· Interfering Medications/Substances
Many drugs and substances can reduce the accuracy of thyroid imaging:
Thyroid hormones (T4, T3),
Antithyroid medications (carbimazole, propylthiouracil),
Iodine-rich foods and medications (e.g., kelp, multivitamins, amiodarone),
Radiographic contrast agents (iodinated CT contrast),
Cough syrups and other OTC supplements.
These may need to be stopped in advance, depending on the radiotracer used.
π· Procedure β How the Scan is Done
π· Procedure β How the Scan is Done
Technetium scan:
Patient lies supine with neck extended.
Imaging begins 20 minutes after injection of the tracer.
Duration: about 20 minutes.
Iodine-based scan:
Patient swallows capsule or liquid iodine.
Imaging is performed 24 hours later.
π· Scan Findings: Interpretation Basics
π· Scan Findings: Interpretation Basics
Hot nodule: Shows increased uptake of tracer, often suppressing normal tissue β usually benign.
Cold nodule: No uptake in the region β may indicate cyst, non-functioning adenoma, or malignancy.
Diffuse uptake: Seen in Gravesβ disease or thyroiditis recovery.
Reduced uptake: May be seen in thyroiditis, iodine overload, or exogenous hormone use.
Example: A scan showing diffuse, symmetric, high uptake is consistent with Gravesβ disease.
π· Side Effects and Safety
π· Side Effects and Safety
No significant side effects from the tracer itself.
The radioactivity is minimal, and most of it leaves the body via urine.
Drinking water and frequent urination help flush the tracer quickly.
π· Special Considerations
π· Special Considerations
Pregnancy is generally a contraindication. Only in life-threatening situations is imaging considered.
Breastfeeding may need to be paused temporarily after the scan β this depends on the radiotracer used. Always consult with the nuclear medicine specialist.
π· Tona
π· Tona
Thyroid imaging with nuclear medicine gives critical information about thyroid function, nodular activity, and residual tissue after surgery. It is the gold standard for evaluating hyperthyroidism, toxic nodules, and thyroiditis, and for differentiating between hot and cold nodules. Proper preparation and understanding of medications are crucial for accurate results. This test complements anatomical imaging like ultrasound by adding functional insight into thyroid disorders.
β’οΈ TOPIC 9: Therapy for Hyperthyroidism with Iodine-131
β’οΈ TOPIC 9: Therapy for Hyperthyroidism with Iodine-131
π· Overview
π· Overview
Hyperthyroidism is a condition in which the thyroid gland produces too much thyroid hormone, leading to symptoms like weight loss, rapid heartbeat, tremors, heat intolerance, and anxiety. One of the most effective long-term treatments is radioiodine therapy using Iodine-131 (ΒΉΒ³ΒΉI).
Because the thyroid naturally absorbs iodine, administering radioactive iodine allows targeted destruction of overactive thyroid tissue, without surgery or general anesthesia.
π· Who Needs This Therapy? (Indications)
π· Who Needs This Therapy? (Indications)
Radioiodine therapy is used in patients with:
Gravesβ disease (toxic diffuse goiter): Autoimmune hyperthyroidism with diffuse gland involvement.
Toxic multinodular goiter (Plummerβs disease): Several overactive nodules causing excess hormone production.
Solitary toxic nodule: One autonomous, overactive nodule suppressing the rest of the gland.
These conditions involve increased iodine uptake, which makes ΒΉΒ³ΒΉI therapy very effective.
π· Why Iodine-131 is Effective
π· Why Iodine-131 is Effective
The thyroid absorbs iodine from the bloodstream to make hormones.
Iodine-131 emits beta radiation, which destroys thyroid cells that take it up.
This leads to reduction or elimination of overactive tissue, restoring normal hormone levels.
π· Patient Preparation
π· Patient Preparation
Before therapy, patients go through a preparation phase:
Consultation and Education
The nuclear medicine specialist meets the patient.
A printed information sheet is often given, including safety instructions and post-treatment precautions.
The patient must understand radiation safety and side effects.
Discontinue Iodine-Containing Products
Stop iodine-rich multivitamins, supplements (like kelp), and medications like amiodarone.
Avoid contrast-enhanced CT scans for several months before therapy.
Topical iodine (like antiseptics) should also be avoided.
Stop Thyroid Hormone Treatment
If on antithyroid drugs (e.g. propylthiouracil, methimazole, carbimazole), these may need to be discontinued a few days before therapy to increase iodine uptake.
If on levothyroxine (T4), this should be paused for 2β6 weeks depending on the protocol.
Pre-treatment Stabilization (Cooling Off)
In elderly patients or those with heart disease (e.g. angina, atrial fibrillation), antithyroid drugs may be used temporarily to reduce hormone levels and prevent a thyroid storm after treatment.
Confirm Pregnancy and Breastfeeding Status
Radioiodine therapy is absolutely contraindicated in pregnancy.
Breastfeeding must be stopped before therapy and cannot be resumed.
π· How the Therapy Is Given
π· How the Therapy Is Given
The patient fasts for 6β12 hours before the treatment.
A calculated dose of Iodine-131 is given orally β usually in a capsule or liquid form.
The patient swallows it with water.
Once inside the body:
The iodine concentrates in the thyroid gland.
Over the next few days to weeks, it destroys the overactive thyroid tissue.
In some cases, hospitalization may be required for radiation protection reasons, especially in regions with stricter safety regulations.
π· Aftercare and Precautions
π· Aftercare and Precautions
After receiving ΒΉΒ³ΒΉI, the patient emits small amounts of radiation. To protect others:
Avoid close contact with others, especially pregnant women and children, for at least 24 hours (sometimes longer depending on dose and local guidelines).
Use separate bathroom facilities if possible, or flush the toilet twice after use.
Wash hands and utensils thoroughly.
Avoid sharing towels, food, or drinks.
Patients should follow the specific radiation safety instructions given by the hospital.
π· Expected Outcome and Follow-Up
π· Expected Outcome and Follow-Up
The effects of the therapy may take 4β8 weeks to appear.
Regular follow-up is necessary to monitor thyroid hormone levels.
Most patients eventually develop hypothyroidism (underactive thyroid), which is expected and manageable with lifelong thyroid hormone replacement (levothyroxine).
Occasionally, a second dose of ΒΉΒ³ΒΉI is needed if hyperthyroidism persists.
π· Side Effects and Risks
π· Side Effects and Risks
Most patients tolerate the treatment well, but possible effects include:
Mild neck pain or tenderness in the thyroid area (inflammation of the gland).
Temporary increase in symptoms (thyroid hormone βflareβ) during the first few days.
Rarely:
Dry mouth,
Taste changes,
Sore throat.
These are typically mild and short-lived.
π· Tona
π· Tona
Radioiodine therapy is a safe, effective, and convenient way to treat hyperthyroidism. It works by targeting and destroying the overactive thyroid tissue with minimal risk to the rest of the body. The procedure requires careful preparation, including stopping interfering medications and observing radiation safety precautions after the dose. The main long-term outcome is hypothyroidism, which is easily treated. This makes ΒΉΒ³ΒΉI therapy a first-line option for many patients with Gravesβ disease, toxic nodules, and multinodular goiters.
π» TOPIC 10: Genito-Urinary Imaging β Renal Scintigraphy (Renography)
π» TOPIC 10: Genito-Urinary Imaging β Renal Scintigraphy (Renography)
π· Overview
π· Overview
Renal scintigraphy, also called a renogram, is a nuclear medicine imaging test used to evaluate the structure and function of the kidneys. It helps assess:
How well each kidney is working individually,
How urine is formed and drained,
The presence of obstruction, scarring, or functional abnormalities.
This test is especially valuable in patients with suspected urinary tract obstructions, reflux, or kidney transplants.
π· How the Procedure Works
π· How the Procedure Works
A radiopharmaceutical tracer (commonly Technetium-99m labeled compounds like MAG3 or DTPA) is injected into the bloodstream. The tracer:
Is filtered or secreted by the kidneys,
Travels through the urinary system,
Is imaged by a gamma camera in real time.
This produces dynamic images, allowing physicians to see how well each kidney filters blood, forms urine, and whether urine flows normally to the bladder.
π· Clinical Indications
π· Clinical Indications
Renal scintigraphy is used in a wide range of kidney-related conditions, including:
Assessment of Individual Kidney Function
Evaluates how much each kidney contributes to overall renal function.
Important in:
Horseshoe kidney, duplex kidneys, or ectopic kidneys (abnormally located).
Kidney donation evaluation β to check donor kidney function.
Post-transplant evaluation β to monitor graft function.
Evaluation of Urine Drainage
Detects urinary obstruction, e.g., pelvi-ureteric junction (PUJ) obstruction.
Monitors patients before and after surgery to relieve obstruction.
Renovascular Hypertension Workup
Helps detect narrowing of renal arteries causing high blood pressure.
A special test called the Captopril Renogram is used:
Performed before and after giving an ACE inhibitor (like Captopril).
Compares kidney function under normal and stress (inhibited) conditions.
Follow-up of Vesico-Ureteric Reflux (VUR)
Can be used with an indirect micturating cystogram to detect backflow of urine from the bladder to the ureters and kidneys.
π· Patient Preparation
π· Patient Preparation
Hydration is essential: The patient should drink plenty of fluids before the test to ensure good urine production and tracer clearance.
For renovascular hypertension workup:
The referring physician must consult with the nuclear medicine specialist several days in advance.
Some antihypertensive medications, especially ACE inhibitors, may need to be stopped.
Timing of withdrawal depends on the specific drug.
For the Captopril study:
The patient takes an oral dose of Captopril (usually 25β50 mg) one hour before the scan.
Blood pressure is monitored during this time.
The patient should not eat solid food for 4 hours prior (water is allowed).
π· Procedure β Step-by-Step
π· Procedure β Step-by-Step
An intravenous (IV) line is established.
The radiotracer is injected.
The patient lies on the imaging table in a supine or sitting position.
Real-time imaging begins immediately, capturing the tracerβs movement through the kidneys, ureters, and bladder.
In some cases (like hydronephrosis), a diuretic (e.g. Lasix) is administered during the scan to assess drainage.
Post-micturition (after urination) images may be taken to assess bladder emptying and backflow.
Total duration: approximately 1 hour.
π· Results Interpretation
π· Results Interpretation
The scan provides information on:
Relative function of each kidney (e.g., Left kidney = 45%, Right kidney = 55%).
Time to peak activity β how fast the tracer is processed.
Drainage curves β to assess flow of urine.
Presence of retention, delayed clearance, or obstruction.
For example:
A normal renogram will show quick uptake and clearance.
A delayed washout curve with persistent tracer may suggest PUJ obstruction.
π· Interfering Factors
π· Interfering Factors
For non-pharmacologic studies, there are typically no interfering medications.
For renovascular hypertension studies, some drugs can affect results and need to be temporarily stopped:
ACE inhibitors:
Must be stopped 3β7 days before the test, depending on the drug.
Diuretics:
Should be paused 2 days before the test.
A consultation with the nuclear medicine physician ensures safe and effective medication management.
π· Safety and Side Effects
π· Safety and Side Effects
The procedure is safe and non-invasive.
There are no side effects from the tracer itself.
Radiation dose is very low.
The tracer is excreted in urine β drinking water and frequent urination after the scan help flush it out.
Special notes:
Pregnancy is a contraindication, unless absolutely necessary.
Breastfeeding is usually not interrupted, but consultation with the nuclear medicine team is advised for each case.
π· Summary in Words
π· Summary in Words
Renal scintigraphy provides a real-time, functional view of the kidneys, making it a vital tool for diagnosing obstruction, reduced function, hypertension, and congenital anomalies. Itβs especially important in evaluating individual kidney performance, particularly in transplantation, pediatric urology, and hypertension. The test is safe, painless, and highly informative β guiding treatment decisions that may prevent kidney damage or avoid unnecessary surgery.
π§ͺ TOPIC 11: Renal Cortical Scintigraphy with DMSA (Dimercaptosuccinic Acid)
π§ͺ TOPIC 11: Renal Cortical Scintigraphy with DMSA (Dimercaptosuccinic Acid)
π· Overview
π· Overview
Renal cortical scintigraphy using Technetium-99m DMSA is a specialized nuclear medicine scan that evaluates the structure and function of the renal cortex β the outer part of the kidneys where most filtration occurs.
It is the most sensitive imaging method for detecting:
Kidney scarring (from previous infections),
Acute pyelonephritis (kidney infection),
Renal anomalies such as ectopic kidneys or horseshoe kidneys.
It also provides accurate assessment of differential renal function (how much each kidney contributes to total kidney function), especially in children.
π· How It Works
π· How It Works
A small dose of Technetium-99m DMSA is injected into the bloodstream.
The tracer binds specifically to renal tubular cells in the renal cortex.
After allowing sufficient time for uptake, images are taken with a gamma camera.
Areas with normal function take up the tracer, while damaged or scarred regions show as cold (defect) areas.
This imaging is usually performed 2 to 3 hours after injection.
π· Clinical Indications
π· Clinical Indications
Acute Pyelonephritis
Detects active inflammation in the renal cortex.
Helps distinguish upper urinary tract infection from lower UTI.
Renal Scarring
Assesses permanent kidney damage from recurrent or severe infections.
Essential in children with vesico-ureteric reflux.
Congenital and Structural Abnormalities
Identifies:
Solitary kidneys,
Ectopic kidneys (e.g. pelvic kidneys),
Horseshoe or pseudohorseshoe kidneys,
Renal duplication anomalies.
Relative Kidney Function
Measures differential (split) renal function.
Especially useful in:
Pre- and post-surgical evaluations,
Deciding on nephrectomy (kidney removal),
Evaluating post-obstructive renal recovery.
Alternative to Iodine Contrast Imaging
Suitable for patients with:
Allergy to iodinated contrast,
Impaired renal function, where contrast may be risky.
Note: For hydronephrosis or dynamic functional assessments, DMSA is not the preferred test. In such cases, MAG3 renogram is better due to lower radiation dose and dynamic evaluation.
π· Patient Preparation
π· Patient Preparation
The patient must be well hydrated before the scan.
No dietary restrictions.
No special medication adjustments are usually required.
The patient (or guardian, in case of children) should be informed about the duration and safety of the test.
π· Procedure β Step-by-Step
π· Procedure β Step-by-Step
The radiotracer (βΉβΉα΅Tc-DMSA) is administered by intravenous injection.
There is a waiting period of 2β3 hours to allow uptake in the kidneys.
During this time, the patient can leave and return later.
Drinking fluids is encouraged to assist excretion of unused tracer.
On return, the patient lies supine on the imaging table.
Multiple static images are taken of the kidneys from different angles.
The scan typically takes 30β45 minutes.
π· Interpretation of Results
π· Interpretation of Results
A normal scan shows:
Symmetrical, well-shaped kidneys with homogeneous cortical uptake.
Clear distinction between renal cortex and collecting system.
Abnormal findings may include:
Focal cortical defects β seen in pyelonephritis or scarring.
In acute infection: areas of inflammation show reduced uptake.
In chronic scarring: areas of permanent loss of uptake (cold spots).
Asymmetry or decreased uptake in one kidney β may indicate reduced function or congenital anomaly.
Example: A scan showing a wedge-shaped defect in the left kidney cortex is suggestive of renal scarring from previous infection.
π· Side Effects and Safety
π· Side Effects and Safety
The test is very safe.
No side effects are expected from the tracer.
The radiation dose is low, but slightly higher than that of dynamic renography (e.g., MAG3 scans).
The radiopharmaceutical is excreted in urine, so patients should drink fluids and urinate frequently after the scan to eliminate it.
π· Special Considerations
π· Special Considerations
Pregnancy is a contraindication, except in rare emergencies.
Breastfeeding mothers should consult with the nuclear medicine team:
Temporary interruption may be needed (typically for 4β6 hours).
The study duration is 3 to 4 hours, including wait time and imaging.
It is commonly used in pediatric patients, especially to evaluate urinary tract infections and reflux-related kidney damage.
π· Tona
π· Tona
DMSA renal scintigraphy is a highly sensitive and specific test for evaluating renal cortical integrity. It is especially valuable in detecting acute infection, chronic scarring, and congenital anomalies of the kidneys. This imaging provides a clear picture of kidney health and function, and is a cornerstone test in pediatric nephrology, urology, and transplant evaluation. The procedure is safe, easy, and provides information that cannot be obtained from ultrasound or CT alone.
π¦ TOPIC 12: Infection and Inflammation Imaging
π¦ TOPIC 12: Infection and Inflammation Imaging
π· Overview
π· Overview
Nuclear medicine plays a vital role in the detection and localization of infection and inflammatory processes, particularly when other diagnostic methods (like X-ray, ultrasound, or CT) are inconclusive.
This technique is especially useful in complex cases such as:
Fever of unknown origin,
Suspected bone or joint infections,
Infected prosthetic implants, and
Systemic infections without a clear source.
It uses specialized tracers that accumulate in areas where the immune system is actively fighting infection or inflammation.
π· How It Works
π· How It Works
Depending on the clinical scenario, different radiopharmaceuticals may be used, including:
Labeled white blood cells (WBCs):
A sample of the patientβs blood is withdrawn, and the white blood cells are tagged with a radioactive tracer (commonly Indium-111 or Technetium-99m).
The labeled cells are then re-injected, and their accumulation in sites of infection is imaged.
Other tracers:
Gallium-67: Localizes in both infection and certain cancers.
FDG-PET (Fluorine-18 fluorodeoxyglucose): Highlights areas of increased metabolic activity, common in both infection and inflammation.
The choice of tracer depends on the suspected infection type, location, and urgency.
π· Clinical Indications
π· Clinical Indications
Nuclear imaging is indicated in various infection-related conditions, especially when diagnosis is unclear:
Fever of Unknown Origin (FUO):
Used when a patient has a persistent fever with no clear source despite initial investigations.
Localization of Infection:
Helps detect the exact site of infection, e.g. intra-abdominal, pelvic, or visceral abscesses.
Extent of Disseminated Infection:
Determines if an infection has spread to multiple organs or systems.
Bone and Joint Infections:
Osteomyelitis: Infection of bone tissue.
Septic arthritis: Infection in the joint space.
Post-surgical infections (e.g. after fracture fixation).
Differentiation between prosthesis infection vs mechanical loosening.
Soft Tissue and Post-Surgical Infections:
Detects surgical wound infections, foreign body reactions, or deep-seated abscesses.
Infected Grafts and Devices:
Detection of vascular graft infections, pacemaker infections, or shunt infections.
Tuberculosis:
Useful in detecting extrapulmonary TB foci, especially in bone, lymph nodes, or abdomen.
π· Patient Preparation
π· Patient Preparation
Preparation depends on the tracer and imaging protocol:
For WBC scans, blood is drawn to isolate and label white cells.
For Gallium or FDG-PET, patients may need to fast.
The nuclear medicine team provides specific instructions based on the planned test.
No significant medication restrictions apply in most cases, but patients should always inform the team about ongoing antibiotics or anti-inflammatory treatment, as this may influence interpretation.
π· Procedure β Step-by-Step (For Labeled WBC Scan)
π· Procedure β Step-by-Step (For Labeled WBC Scan)
A small amount of blood is drawn from the patient.
White blood cells are separated and labeled with a radioactive tracer.
The labeled cells are then re-injected intravenously.
Imaging is performed in several phases:
Early images within a few hours,
Delayed images at 24 hours, and sometimes 48 hours.
The gamma camera captures images to identify areas where white cells accumulate β indicating infection or inflammation.
π· Interpretation of Results
π· Interpretation of Results
Normal result: White blood cells localize only in spleen, liver, bone marrow, and urinary tract (normal sites).
Abnormal uptake in bones, joints, soft tissues, or other organs suggests localized infection or inflammation.
For example:
A patient with vague abdominal symptoms may show intense tracer uptake in the right pelvic region, indicating an abscess.
π· Side Effects and Safety
π· Side Effects and Safety
The procedures are safe and well tolerated.
No significant allergic reactions or side effects are expected.
The radioactive dose is low, and most tracers are eliminated through urine or feces.
However:
Pregnancy is a contraindication β these tests should not be performed unless absolutely necessary.
Breastfeeding may need to be paused depending on the tracer used. The nuclear medicine specialist will provide guidance.
π· Time and Follow-Up
π· Time and Follow-Up
Some studies require the patient to return multiple times over 24β48 hours.
This is essential for accurate localization and differentiation between early infection and chronic inflammation.
Communication with the treating physician is important for integrating results with clinical and laboratory findings.
π· Kusufazo;
π· Kusufazo;
Nuclear imaging for infection and inflammation provides a powerful method to detect hidden sources of infection, evaluate complex post-surgical cases, and distinguish between infectious and non-infectious causes of inflammation. By using radiolabeled tracers β especially labeled white cells β this method offers functional insights that are often not visible on standard imaging. It is a crucial tool in diagnosing fevers of unknown origin, bone and prosthetic infections, and systemic sepsis.
π« TOPIC 13: Pulmonary Imaging β Lung Scintigraphy for Pulmonary Embolism Detection
π« TOPIC 13: Pulmonary Imaging β Lung Scintigraphy for Pulmonary Embolism Detection
π· Overview
π· Overview
Lung scintigraphy, also known as a V/Q scan (ventilation/perfusion scan), is a nuclear medicine test used to detect pulmonary embolism (PE) β a life-threatening condition where a blood clot blocks blood flow in the lungs.
This scan assesses:
Ventilation β How well air moves through the lungs.
Perfusion β How well blood flows through the lung tissues.
By comparing these two functions, the scan can identify mismatched areas suggestive of embolism.
π· Why Itβs Used
π· Why Itβs Used
V/Q scans are used when:
A patient has suspected pulmonary embolism and cannot undergo CT pulmonary angiography (CTPA),
e.g., due to iodine contrast allergy or kidney failure.
A patient is pregnant and CTPA would expose the fetus to higher radiation.
Evaluation of regional lung function before lung surgery.
π· How the V/Q Scan Works
π· How the V/Q Scan Works
The V/Q scan consists of two parts:
Ventilation Scan (V):
The patient inhales a radioactive gas or aerosol (e.g., Technegas or Xenon-133).
This shows how air spreads through the lungs.
Areas not ventilated properly (e.g. in COPD or collapsed lung) appear as ventilation defects.
Perfusion Scan (Q):
A small amount of radiolabeled particles (βΉβΉα΅Tc-MAA) is injected into a vein.
These particles lodge in the small blood vessels of the lungs.
Areas of normal blood flow light up, while blocked areas (due to clots) appear as cold spots.
A mismatch between a well-ventilated area (normal V) and poorly perfused area (abnormal Q) suggests pulmonary embolism.
π· Patient Preparation
π· Patient Preparation
No special preparation is needed.
The patient should ideally:
Avoid food 2 hours before the ventilation scan (to reduce nausea risk).
Inform the staff of any respiratory conditions (as breathing in the tracer may be difficult).
Pregnancy status must be confirmed β V/Q scans are generally safe in pregnancy, but protocol may be adjusted.
π· How the Procedure Is Performed
π· How the Procedure Is Performed
Ventilation Phase:
The patient inhales the radioactive gas or aerosol.
Gamma camera captures real-time images of air distribution in the lungs.
This takes 5β10 minutes.
Perfusion Phase:
The patient lies on the table.
A small amount of 99mTc-MAA is injected intravenously.
The camera captures static images from multiple angles over 10β20 minutes.
Total procedure time: 30β45 minutes.
π· Interpreting the Results
π· Interpreting the Results
The key to interpretation is comparing ventilation and perfusion images.
Normal V + Normal Q β Normal scan.
Matched defect (abnormal V and Q in the same region) β Suggests non-embolic disease (e.g., pneumonia, COPD).
Mismatch (normal ventilation but reduced perfusion) β Suggests pulmonary embolism.
Multiple segmental mismatches β Strongly supports PE diagnosis.
Example: A V/Q scan shows normal ventilation throughout the lungs but segmental perfusion defects in the right lower lobe β this is highly suspicious for PE.
π· Advantages of V/Q Scanning
π· Advantages of V/Q Scanning
No iodinated contrast β safer for patients with renal failure or contrast allergy.
Lower radiation exposure to the breast and fetus β suitable in pregnancy.
Effective even in patients with poor IV access or limited mobility.
Quick and non-invasive.
π· Limitations
π· Limitations
Less specific in patients with pre-existing lung disease (e.g., COPD, fibrosis).
Sometimes results are indeterminate β may need correlation with clinical findings or further imaging.
Requires cooperative breathing for accurate ventilation images.
π· Safety and Side Effects
π· Safety and Side Effects
Very safe procedure with minimal radiation.
The radioactive gas or aerosol is inhaled briefly and poses no long-term risk.
The radiolabeled particles in the perfusion scan are filtered out by the lungs and eventually excreted in urine.
Allergic reactions are rare.
Pregnant women must inform the team β adjusted protocols reduce fetal exposure.
π· Kusufazo;
π· Kusufazo;
Lung scintigraphy (V/Q scan) is a fast, non-invasive, and safe method to detect pulmonary embolism, especially when CT scans are unsuitable. By comparing air flow and blood flow in the lungs, it identifies clots blocking pulmonary circulation. It is especially useful in pregnancy, renal failure, and contrast allergy. The scan provides valuable information even in cases of unexplained breathlessness or pre-operative lung assessment.
ποΈ TOPIC 14: Sentinel Node Scintigraphy in Oncology
ποΈ TOPIC 14: Sentinel Node Scintigraphy in Oncology
π· Overview
π· Overview
Sentinel node scintigraphy is a nuclear medicine technique used in cancer management to identify the first lymph node(s) that cancer cells are likely to spread to from the primary tumor site.
This βfirst stopβ lymph node is called the sentinel lymph node. By locating and analyzing it, doctors can determine:
Whether cancer has started to spread,
Whether further lymph node removal is necessary, and
Help plan appropriate cancer treatment (surgery, chemotherapy, radiation).
This technique is minimally invasive, accurate, and helps avoid unnecessary surgery.
π· Clinical Use and Indications
π· Clinical Use and Indications
Sentinel node scintigraphy is routinely used in:
Breast cancer
To check for spread into axillary lymph nodes.
Helps avoid full axillary clearance if nodes are uninvolved.
Malignant melanoma
Especially in lesions on the trunk, head, neck, or limbs.
Identifies regional lymph node basins.
Penile cancer, vulvar cancer, and cervical cancer
For targeted lymph node evaluation.
Head and neck cancers
Helps plan less aggressive surgery by avoiding unnecessary removal of all nodes.
π· Why Itβs Important
π· Why Itβs Important
Traditional surgery involved removal of many lymph nodes, which can cause:
Lymphedema (swelling of limbs),
Nerve injury,
Chronic pain.
Sentinel node scintigraphy allows a targeted approach:
Only the first node(s) likely to harbor cancer cells are removed.
If these nodes are cancer-free, the rest are likely clear too.
This improves patient outcomes while reducing side effects.
π· How the Procedure Works
π· How the Procedure Works
A radiotracer (usually βΉβΉα΅Tc-nanocolloid or sulfur colloid) is injected near the tumor site.
Often intradermal, subcutaneous, or peritumoral depending on tumor type.
The tracer travels through lymphatic channels to reach the draining lymph nodes.
A gamma camera captures images, identifying nodes that accumulate the tracer β these are the sentinel nodes.
During surgery:
A handheld gamma probe is used to locate and remove the node.
Sometimes a blue dye is also injected for visual confirmation.
The node is then sent for pathology to check for cancer cells.
π· Timing and Logistics
π· Timing and Logistics
Imaging is typically done 1β4 hours after injection.
Surgery may be done the same day or the next day, depending on the tracer and schedule.
The procedure is coordinated closely between:
Nuclear medicine team,
Surgeons,
Pathologists.
π· Patient Preparation
π· Patient Preparation
No special fasting or dietary restrictions.
Patients should inform staff about allergies, especially to blue dye (if being used).
The injection may cause mild local discomfort, like a small sting or pressure.
Pregnancy status must be confirmed prior to injection.
π· Interpretation of Results
π· Interpretation of Results
Images show the path of lymphatic drainage and the number and location of sentinel nodes.
This helps:
The surgeon plan the incision site.
Determine whether multiple nodes need to be removed.
Example: In breast cancer, if a scan shows uptake in only one axillary node, that single node will be biopsied instead of removing many.
π· Advantages of Sentinel Node Imaging
π· Advantages of Sentinel Node Imaging
Minimally invasive β reduces unnecessary surgery.
Highly accurate β identifies true first-line nodes.
Better patient outcomes β less pain, scarring, and faster recovery.
Can detect unusual drainage patterns, e.g., breast cancer draining to internal mammary nodes.
π· Safety and Side Effects
π· Safety and Side Effects
Very safe procedure with tiny amounts of radioactivity.
Tracer is confined to lymph nodes and excreted safely.
No known serious side effects.
Blue dye may cause temporary discoloration of the skin, and in rare cases, allergic reactions.
π· Kusufazo;
π· Kusufazo;
Sentinel node scintigraphy is a powerful and precise tool in cancer care. It identifies the first lymph node(s) that cancer could spread to, helping avoid unnecessary lymph node surgery. Commonly used in breast cancer and melanoma, this imaging technique improves surgical outcomes, reduces complications, and allows personalized cancer treatment. It is safe, quick, and has become a standard of care in modern oncology.
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