Recent papers

You can find the full list with my publications in my Google Citations page. Here is a selection of my papers in medical physics, each with a brief blurb:

  • Impact of time-of-flight on PET tumor detection, Dan J Kadrmas, Michael E Casey, Maurizio Conti, Bjoern W Jakoby, Cristina Lois & David W Townsend, J Nucl Med, vol. 50 no. 8 1315-1323 (2009).
    • In this paper, we study the benefits of incorporating time-of-flight information to PET imaging using a new prototype developed by Siemens. Time-of-flight PET uses faster detectors and electronics to retrieve the information about the difference in the time of arrival of the pair of photons to the opposed detectors. As both photons were originated simultaneously after a positron-electron annihilation inside the patient's body, this time-of-flight difference allows us to locate the precise point where the desintegration occurred along the line joining the two points of detection. This increases significantly the signal to noise ratio of the scan and allows better imaging with the same dose administered. In this paper we presented a detailed study using a complex phantom and performed also some theoretical modeling. This was one of the papers I published as a postdoc in Tennessee working in Prof. David Townsend's group and is a collaboration with Siemens. One figure in the paper was chosen as the cover image for the August 2009 issue of the Journal of Nuclear Medicine.
  • An assessment of the impact of incorporating time-of-flight information into clinical PET/CT imaging, Cristina Lois, Bjoern W Jakoby, Misty J Long, Karl F Hubner, David W Barker, Michael E Casey, Maurizio Conti, Vladimir Y Panin, Dan J Kadrmas & David W Townsend, J Nucl Med vol. 51 no. 2 237-245 (2010).
    • In this paper, we extend our previous work on the benefits of incorporating time-of-flight information in PET to clinical practice. We performed a clinical study on 100 oncological patients from the University of Tennessee Medical Center using a new prototype of time-of-flight PET developed by Siemens. Our conclusions are that time-of-flight information greatly increases the signal to noise ratio improving the image quality at equal dose. Equivalently one can administer half of the dose and by using time-of-flight information get a similar image as with the full dose and no time-of-flight information. This is a benefit for the patient who gets less radiation and spends less time inside the machine. Our work also shows that the improvement in the signal to noise ratio, and therefore in the image quality, is better the larger the body mass index of the patient, i.e. incorporating time-of-flight information is more important, when not crucial, for overweighted patients. This was the second paper I published as a postdoc working in Tennessee and was also done in collaboration with Siemens.
  • Effect of MR contrast agents on quantitative accuracy of PET in combined whole-body PET/MR imaging, Cristina Lois, Ilja Bezrukov, Holger Schmidt, Nina Schwenzer, Matthias K Werner, Jürgen Kupferschläger & Thomas Beyer, European Journal of Nuclear Medicine and Molecular Imaging vol. 39, no 11, pp 1756-1766 (2012).
    • In this paper, we evaluate different contrast agents used in clinical magnetic resonance for its use as contrast agents in PET/MR imaging. With this work I started to do PET/MR imaging, after my previous research on PET/CT. PET/MR combines the use of information coming from a PET scan with that coming from a magnetic resonance (MR). To be able to take both images at the same time, the patient has to take two different substances: one visible by PET (a derivative of glucose containing a positron emitter isotope of fluor), and one visible by MR. While we are pretty limited on which substance to choose on the PET side, there are ample choices on the MR side (among them pineapple juice!). However, the choice of the MR contrast agent (as the substance administered to the patient to be MR'ed is called) can affect what we get from PET, as it may attenuate the image, blurring some important details. The aim of our work was to evaluate different contrast agents commonly used for MR imaging to assest the effects they had on the PET images when used in PET/MR imaging. We used both phantoms (not scary souls wandering on the world of the alive, but a sort of medical test dummy), and human patients. We conclude that constrast agents effects on PET are not significant once certain precautions are taken. (As you may guess pineapple juice proved to be one of the winners for best PET/MR constrast agent.) This work was performed as part of a research stay on Tübingen, while I worked as a postdoc in Santiago.