Publications (- 2018)

J15. H. K. Zhang, A. Cheng, Y. Kim, Q. Ma, G. S. Chirikjian, E. M. Boctor, “A Phantom with Multiple Active Points for Ultrasound Calibration”, in Journal of Medical Imaging, 5(4), 045001, 2018, Link.

J14. E. M. A. Anas, H. K. Zhang, J. Kang, E. M. Boctor, “Enabling Fast and High Quality LED Photoacoustic Imaging: A Recurrent Neural Networks Based Approach”, in Biomedical Optics Express, 9(8), 3852, 2018, Open Access.

J13. J. Kang, E. M. Boctor, S. Adams, E. Kulikowicz, H. K. Zhang, K. Raymond, and E. Graham, “Validation of Noninvasive Photoacoustic Measurements of Sagittal Sinus Oxyhemoglobin Saturation in Hypoxic Neonatal Piglets”, in Journal of Applied Physiology, 125(4), 983-989, 2018, Link.

J12. [H. K. Zhang, Y. Chen], J. Kang, A. Lisok, I. Minn, [M. G. Pomper, and Emad M. Boctor], “Prostate Specific Membrane Antigen (PSMA)-Targeted Photoacoustic Imaging of Prostate Cancer In Vivo”, in Journal of Biophotonics, e201800021, 2018, Link.

J11. H. K. Zhang, Y. Kim, M. Lin, M. Paredes, K. Kannan, A. Moghekar, N. Durr, E. M. Boctor, “Toward dynamic lumbar puncture guidance using needle-based single element ultrasound imaging”, in Journal of Medical Imaging, 5(2), 021224, 2018, Link.

J10. A. Cheng, Y. Kim, Y. Itsarachaiyot, H. K. Zhang, C. R. Weiss, R. H. Taylor, E. M. Boctor, “Photoacoustic-based catheter tracking: simulation, phantom, and in vivo studies”, in Journal of Medical Imaging, 5(2), 021223, 2018, Link.

J9. A. Cheng, X. Guo, H. K. Zhang, H. J. Kang, R. Etienne-Cummings, and E. M. Boctor, “Active phantoms: a new paradigm for ultrasound calibration using phantom feedback”, in Journal of Medical Imaging, 4(3), 035001, 2017, Link.

J8. [H. K. Zhang, P. Yan], J. Kang, D. S. Abou, H. N. D. Le, A. K. Jha, D. L. J. Thorek, J. U. Kang, A. Rahmim, D. F. Wong, [Emad M. Boctor, Leslie M. Loew], “Listening to membrane potential: Photoacoustic voltage sensitive dye recording”, in Journal of Biomedical Optics, 22(4), 045006, 2017, PDF.

J7. T.-Y. Fang, H. K. Zhang, R. Finocchi, R. H. Taylor, E. M. Boctor, “Force Assisted Ultrasound Imaging System through Dual Force Sensing and Admittance Robot Control”, in International Journal for Computer Assisted Radiology and Surgery (IJCARS), 12(6), 983-991, 2017, Link.

J6. H. K. Zhang, M. Bell, X. Guo, H. J. Kang, Emad M. Boctor, "Synthetic-aperture based photoacoustic re-beamforming (SPARE) approach using beamformed ultrasound data", in Biomedical Optics Express, 7(8), 3056-3068, 2016, Open Access.

J5. H. K. Zhang, A. Cheng, N. Bottenus, X. Guo, G. E. Trahey, Emad M. Boctor, "Synthetic Tracked Aperture Ultrasound (STRATUS) Imaging: Design, Simulation, and Experimental Evaluation", in Journal of Medical Imaging, 3(2), 027001, 2016, Open Access.

J4. N. Bottenus, W. Long, H. K. Zhang, M. Jakovljevic, D. P. Bradway, E. M. Boctor, G. E. Trahey, "Feasibility of Swept Synthetic Aperture Ultrasound Imaging", in IEEE Transactions on Medical Imaging, 35(7), 1676-1685, 2016.

J3. F. Aalamifar, A. Cheng, Y. Kim, X. Hu, H. K. Zhang, X. Guo, E. M. Boctor, “Robot Assisted Automatic Ultrasound Calibration”, in International Journal of Computer Assisted Radiology and Surgery (IJCARS), 11(10), 1821-1829, 2016.

J2. H. K. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, "Coded Excitation Using Periodic and Unipolar M-sequences for Photoacoustic Imaging and Flow Measurement", in Optics Express, 24(1), 17-29, 2016, Open Access.

J1. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, "Simultaneous Multispectral Coded Excitation Using Gold Codes for Photoacoustic Imaging", in Jpn. Journal of Applied Physics, 51 (7), 07GF03, 2012, PDF.

C32. E. M. A. Anas, H. K. Zhang, J. Kang, E. M. Boctor, “Towards a Fast and Safe LED-based Photoacoustic Imaging using a Deep Convolutional Neural Networks" (MICCAI), 2018.

C31. [H. K. Zhang, Y. Kim], A. Moghekar, N. J. Durr, and E. M. Boctor, "Single-Element Needle-Based Ultrasound Imaging of Spine: An In Vivo Feasibility Study" (MICCAI Workshop: POCUS), 2018.

C30. E. M. A. Anas, H. K. Zhang, J. Kang, E. M. Boctor, "Robust Photoacoustic Beamforming using Dense Convolutional Neural Networks" (MICCAI Workshop: POCUS), 2018.

C29. Y. Wu, H. K. Zhang, E. M. Boctor, “Enabling vendor independent photoacoustic imaging systems with asynchronous laser source”, in Proc. SPIE, 10494, 104945M, 2018.

C28(=J7). T.-Y. Fang, H. K. Zhang, R. Finocchi, R. H. Taylor, E. M. Boctor, “Force Assisted Ultrasound Imaging System through Dual Force Sensing and Admittance Robot Control”, in Information Processing in Computer-Assisted Interventions (IPCAI), 2017.

C27. H. K. Zhang, T. Y. Fang, R. Finocchi, E. M. Boctor, “High Resolution Three-Dimensional Robotic Synthetic Tracked Aperture Ultrasound Imaging: Feasibility Study”, in SPIE Medical Imaging, 10139, 1013914, 2017.

C26. H. K. Zhang, M. Lin, Y. Kim, N. Patel, A. Moghekar, N. Durr, E. M. Boctor, “Toward Dynamic Lumbar Punctures Guidance Based on Single Element Synthetic Tracked Aperture Ultrasound Imaging”, in SPIE Medical Imaging, 10135, 101350J, 2017, Runner-up, Young Scientist Award.

C25. H. K. Zhang, J. Kang, P. Yan, D. Abou, H. N. D. Le, D. Thorek, J. U. Kang, A. Gjedde, A. Rahmim, D. F. Wong, L. M. Loew, E. M. Boctor, “Listening to membrane potential: Photoacoustic voltage sensitive dye recording”, in SPIE Photonics West BiOS, 2017.

C24. H. K. Zhang, H. Huang, L. Chen, Y. Kim, E. M. Boctor, “Software-based Approach Toward Vendor-Independent Real-time Photoacoustic Imaging Using Ultrasound Beamformed Data”, in SPIE Photonics West BiOS, 10064, 100643O, 2017.

C23. J. Kang, H. K. Zhang, A. Rahmim, D. F. Wong, J. U. Kang, E. M. Boctor, “Toward high-speed transcranial photoacoustic imaging using compact near-infrared pulsed LED illumination system”, in SPIE Photonics West BiOS, 2017.

C22. J. Kang, H. N. D. Le, H. K. Zhang, J. U. Kang, M. M. Harraz, E. M. Boctor, “Initial proof-of-concept of photoacoustic cell stimulation approach: preliminary in vitro study”, in SPIE Photonics West BiOS, 2017.

C21. A. Cheng, H. K. Zhang, J. U. Kang, R. H. Taylor, E. M. Boctor, “Localization of subsurface photoacoustic fiducials for intraoperative guidance”, in SPIE Photonics West BiOS, 2017.

C20. H. K. Zhang, X. Guo, B. Tavakoli, E. M. Boctor, "Photoacoustic Imaging Paradigm Shift: Towards Using Vendor-Independent Ultrasound Scanners", in Medical Image Computing and Computer-Assisted Intervention (MICCAI), 9900, 585-592, 2016

C19. H. K. Zhang, Rodolfo Finocchi, Kalyna Apkarian, E. M. Boctor, "Co-Robotic Synthetic Tracked Aperture Ultrasound Imag-ing with Cross-Correlation Based Dynamic Error Compen-sation and Virtual Fixture Control", in Proceedings of IEEE International Ultrasonics Symposium (IUS), 2016 (DOI: 10.1109/ULTSYM.2016.7728522)

C18. A. Cheng, H. K. Zhang, E. M. Boctor, "Catheter Tracking in an Interventional Photoacoustic Surgical System", in Proceedings of CLEO, 2016, San Jose

C17. H. K. Zhang, A. Cheng, E. M. Boctor, "Three-dimensional Photoacoustic Imaging Using Robotically Tracked Transrectal Ultrasound Probe with Elevational Synthetic Aperture Focusing", in Proceedings of CLEO, 2016, San Jose

C16. A. Cheng, H. J. Kang, H. K. Zhang, R. H. Taylor, E. M. Boctor, "Ultrasound to video registration using a bi-plane transrectal probe with photoacoustic markers", in Proceedings of SPIE Medical Imaging, 9786, 97860J, 2016, San Diego

C15. H. K. Zhang, F. Aalamifar, G. E. Trahey, E. M. Boctor, "In vivo visualization of robotically implemented Synthetic Tracked Aperture Ultrasound (STRATUS) imaging system using curvilinear array", in Proceedings of SPIE Medical Imaging, 9790, 97901X, 2016, San Diego

C14. F. Aalamifar, H. K. Zhang, A. Rahmim, E. M. Boctor, "Image reconstruction for robot assisted ultrasound tomography", in Proceedings of SPIE Medical Imaging, 9790, 979017, 2016, San Diego

C13. H. K. Zhang, X. Guo, H. J. Kang, and E. M. Boctor, "Photoacoustic image reconstruction from ultrasound post-beamformed B-mode image", in Proceedings of SPIE Photonics West BiOS 2016, 9708, 970837, 2016, San Francisco

C12. A. Cheng, X. Guo, H. K. Zhang, H. J. Kang, R. Etienne-Cummings, and E. M. Boctor, “Active point out-of-plane ultrasound calibration”, in Proceedings of SPIE Medical Imaging, 2015, Florida

C11. H. K. Zhang, F. Aalamifar, H-J Kang, E. M. Boctor, “Feasibility Study of Robotically Tracked Photoacoustic Computed Tomography”, in Proceedings of SPIE Medical Imaging, 2015, Florida

C10. H. K. Zhang, E. Ergun, G. E. Trahey, E. M. Boctor, “Synthetic Aperture Ultrasound Imaging with Robotic Aperture Extension”, in Proceedings of SPIE Medical Imaging, 2015, Florida

C9. F. Aalamifar, D. Jiang, H. K. Zhang, A. Cheng, X. Guo, E. M. Boctor, “Dual robotic arm ultrasound tomography: system setup and preliminary tomographic reconstruction”, in Proceedings of SPIE Medical Imaging, 2015, Florida

C8. H. K. Zhang, X. Guo, H-J Kang, and E. M. Boctor, “Photoacoustic reconstruction using beamformed RF data: a synthetic aperture imaging approach”, in Proceedings of SPIE Photonics West BiOS 2015, 9419, 94190L, 2015, San Francisco

C7. M. Azuma, H. K. Zhang, K. Kondo, T. Namita, M. Yamakawa, T. Shiina, “High frame rate photoacoustic computed tomography using coded excitation”, in Proceedings of SPIE Photonics West BiOS 2015, 2015, San Francisco

C6. M. Azuma, H. K. Zhang, K. Kondo, T. Namita, M. Yamakawa, T. Shiina, “Simulation analysis of high frame rate and high quality photoacoustic computed tomography using coded excitation”, in Proceedings of Symposium on Ultrasonic Electronics, 2014, Tokyo

C5. X. Guo, A. Cheng, H. K. Zhang, H-J Kang, R. Etienne-Cummings and E. M. Boctor, “Active Echo: A new Paradigm for Ultrasound Calibration”, in MICCAI, 2014, Boston

C4. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Photoacoustic Flow Measurement with Ultra-High Temporal Resolution by Coded Excitation”, in 2013 IEEE Joint UFFC, EFTA and PFM Symposium (IUS), 2013, Prague

C3. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Simultaneous Multispectral Coded Excitation Using Periodic and Unipolar M-sequence for Photoacoustic Imaging”, in Proceedings of SPIE Photonics West BiOS 2013, 2013, San Francisco

C2. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Simultaneous Multispectral Coded Excitation for Photoacoustic Imaging”, in 2012 IEEE International Ultrasonics Symposium, 2012, Dresden

C1. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Simultaneous Multispectral Coded Excitation Using Gold Codes for Photoacoustic Imaging”, in Proceedings of Symposium on Ultrasonic Electronics, Vol. 32, 2011, pp. 269-270, Kyoto

P30. H. K. Zhang, J. Kang, A. Malla, A. Lisok, Z. M. Bhujwalla, M. G. Pomper, [M. Harraz, E. M. Boctor], "Bioelectric identification of aggressive prostate cancer using ultrasound cell stimulation", IEEE International Ultrasonics Symposium, 2018, Kobe.

P29. A. Cheng, Y. Kim, Y. Itsarachaiyot, H. K. Zhang, C. R. Weiss, R. H. Taylor, E. M. Boctor, “Photoacoustic-based catheter tracking: simulation, phantom and in vivo studies”, Ultrasonic Imaging and Tissue Characterization Symposium, 2018, Virginia.

P28. H. K. Zhang, Y. Chen, J. Kang, A. Lisok, I. Minn, M. G. Pomper, E. M. Boctor, “In vivo demonstration of spectroscopic photoacoustic molecular imaging of prostate cancer”, Ultrasonic Imaging and Tissue Characterization Symposium, 2018, Virginia.

P27. Y. Wu, H. K. Zhang, E. M. Boctor, “Feasibility of low-cost photoacoustic imaging using clinical ultrasound scanners without laser synchronization”, Ultrasonic Imaging and Tissue Characterization Symposium, 2018, Virginia.

P26. E. Anas, H. K. Zhang, E. M. Boctor , "Deep neural networks for photoacoustic imaging using LED lightsource", Ultrasonic Imaging and Tissue Characterization Symposium, 2018, Virginia.

P25. J. Kang, H. K. Zhang, S. Kadam, J. Elmore, H. Valentine, Y. Yan, J. U. Kang, A. Rahmim, A. Gjedde, L. M. Loew, D. F. Wong, E. M. Boctor, "In-vivo imaging of neurotransmitter modulation of brain network activity using transcranial photoacoustic voltage-sensitive dye imaging", Ultrasonic Imaging and Tissue Characterization Symposium, 2018, Virginia.

P24. H. K. Zhang, J. Kang, E. M. Boctor, “In vivo low-cost photoacoustic imaging using LED light source and clinical ultrasound scanner,” in SPIE Photonics West, 10494-177, San Francisco, USA, 2018.

P23. H. K. Zhang, Y. Chen, J. Kang, A. Lisok, M. G. Pomper, E. M. Boctor, “In vivo photoacoustic prostate cancer imaging using PSMA-targeting contrast agents”, in SPIE Photonics West, 10494-22, San Francisco, USA, 2018.

P22. J. Kang, S. Kadam, H. K. Zhang, H. Valentine, J. Fedorko, D. F. Wong, and E. M. Boctor, “Transcranial recording of stimulated neuronal activity variation in vivo using photoacoustic voltage-sensitive dye imaging”, in SPIE Photonics West, 10494-53, San Francisco, USA, 2018.

P21. J. Kang, H. K. Zhang, S. Adams, E. Graham, R. Koehler, and Emad M. Boctor, “Non-invasive photoacoustic diagnosis of perinatal arterial ischemic stroke: preliminary in vivo validation using bilateral carotid occlusion in neonatal piglet”, in SPIE Photonics West, 10494-159, San Francisco, USA, 2018.

P20. J. Kang, S. Kadam, H. K. Zhang, H. Valentine, J. Fedorko, D. F. Wong, and E. M. Boctor, “Real-time Recording of Neuronal Voltage Membrane Variation during Seizure using Transcranial Photoacoustic Voltage-Sensitive Dye Imaging,” IEEE International Ultrasonics Symposium, 4B-4, Washington DC, USA, 7 Sep. 2017.

P19. J. Kang, H. K. Zhang, E. Kulikowicz, E. Graham, R. Koehler, and Emad M. Boctor, “In Vivo Photoacoustic Quantification of Brain Tissue Oxygenation for Neonatal Piglet Graded Ischemia Model using Microsphere Administration,” IEEE International Ultrasonics Symposium, 4E-5, Washington DC, USA, 8 Sep. 2017.

P18. J. Kang, H. K. Zhang, P. Yan, D. Abou, H. N. D. Le, A. K. Jha, D. Thorek, J. Kang, A. Rahmim, D. F. Wong, Leslie M Loew, Emad M Boctor, “Listening to Membrane Potential with a Photoacoustic Voltage Sensitive Dye”, Radiology Day, Johns Hopkins Medicine, 2017, Baltimore, Best Poster Award (Pre-clinical).

P17. H. K. Zhang, T. Y. Fang, R. Finocchi, E. M. Boctor, “Cooperatively Controlled Three-Dimensional Robotic Synthetic Tracked Aperture Ultrasound Imaging”, Radiology Day, Johns Hopkins Medicine, 2017, Baltimore, Best Poster Award (Clinical).

P16. H. K. Zhang, T. Y. Fang, R. Finocchi, E. M. Boctor, “Cooperatively-controlled three-dimensional robotic synthetic tracked-aperture ultrasound imaging”, Ultrasonic Imaging and Tissue Characterization Symposium, 2017, Virginia.

P15. J. Kang, Raymond C. Kohler, H. K. Zhang, Ernest Graham, Emad M. Boctor, “Photoacoustic quantification of brain-tissue oxygenation for focal stroke pig let model in vivo”, Ultrasonic Imaging and Tissue Characterization Symposium, 2017, Virginia.

P14. H. K. Zhang, J. Kang, P. Yan, D. Abou, H. N. D. Le, A. K. Jha, D. Thorek, J. Kang, A. Rahmim, D. F. Wong, Leslie M Loew, Emad M Boctor, “Listening to Membrane Potential Change through Photoacoustic Voltage Sensitive Dye”, Ultrasonic Imaging and Tissue Characterization Symposium, 2017, Virginia.

P13. H. K. Zhang, P. Yan, J. Kang, D. Abou, H. N. D. Le, A. K. Jha, D. Thorek, J. Kang, A. Rahmim, D. F. Wong, Emad M Boctor, Leslie M Loew, “Photoacoustics as a New Modality for Recording Membrane Potential Changes”, Biophysical Society Annual Meeting, 2017, New Orleans

P12. H. K. Zhang, F. Aalamifar, R. Finocchi, K. Apkarian and E. M. Boctor, “System development for robotically-implemented synthetic tracked aperture ultrasound imaging”, Ultrasonic Imaging and Tissue Characterization Symposium, 2016, Virginia

P11. F. Aalamifar, H. K. Zhang, A. Rahmim, E. M. Boctor, “Tomographic reconstruction of speed-of-sound using two robotically-aligned ultra sound probes”, Ultrasonic Imaging and Tissue Characterization Symposium, 2016, Virginia

P10. F. Aalamifar, A. Cheng, X. Guo, H.K. Zhang, E.M. Boctor, “Robot-assisted automatic ultrasound calibration”, Computer Assisted Radiology and Surgery (CARS), 2015, Barcelona, Spain

P9. H. K. Zhang, N. Bottenus, A. Cheng, G. E. Trahey, E. M. Boctor, “Synthetic-tracked aperture ultra sound imaging using robotic guidance”, Ultrasonic Imaging and Tissue Characterization Symposium, 2015, Virginia

P8. F. Aalamifar, H. K. Zhang, D. Jiang, I. Iordachita, E. M. Boctor, “Dual robotic-arm ultrasound tomography: system set-up and error analysis”, Ultrasonic Imaging and Tissue Characterization Symposium, 2015, Virginia

P7. M. Azuma, H. K. Zhang, K. Kondo, T. Namita, M. Yamakawa, T. Shiina, “High frame rate and high quality photoacoustic computed tomography using coded excitation”, in 4th Japanese Photoacoustic Imaging Meeting 2014, 2015, Tokyo (in Japanese)

P6. H. K. Zhang, A. Cheng, F. Aalamifar, H-J Kang, G. E. Trahey, E. M. Boctor, “Robotic 2D Ultrasound Calibration Utilizing Trajectory of Moved Phantom”, Ultrasonic Imaging and Tissue Characterization Symposium, 2014, Virginia

P5. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Coded Excitation for Photoacoustic Imaging and Velocity Estimation”, in 1st Japanese Photoacoustic Imaging Meeting 2013, 2013, Kyoto (in Japanese)

P4. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Simultaneous Multispectral Photoacoustic Imaging by Coded Excitation Using Periodic and Unipolar M-sequence”, in Proceedings of The 86th Annual Scientific Meeting of the Japan Society of Ultrasonics in Medicine, 2013 (in Japanese), Osaka

P3. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Simultaneous Multispectral Coded Excitation Using Aperiodic M-sequence Family for Photoacoustic Imaging”, in Japanese Photoacoustic Imaging Meeting 2012, 2012, Kyoto (in Japanese)

P2. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Experimental Evaluation of Simultaneous Multispectral Coded excitation for Photoacoustic Imaging”, in Proceedings of International Tissue Elasticity Conferences, 2012, Deauville

P1. H. Zhang, K. Kondo, M. Yamakawa, T. Tsuyoshi, “Experimental Evaluation of Simultaneous Multispectral Photoacoustic Imaging by Coded Excitation”, in Proceedings of The 85th Annual Scientific Meeting of the Japan Society of Ultrasonics in Medicine, 85-基-008, 2012 (in Japanese), Tokyo

I6. H. K. Zhang, "Recording the sound of light and imaging with compliant robots: co-robotic paradigm in biomedical ultrasound and photoacoustic imaging of brain and cancer", at Worcester Polytechnic Institute, Worcester, MA, 2018.

I5. H. K. Zhang, "Paradigm Shift on Medical Ultrasound: Robotic Ultrasound and Functional Photoacoustic Imaging", at Nara Institute of Science and Technology, Nara, Japan, 2017.

I4. H. K. Zhang, "Development of Advanced Medical Ultrasound Imaging Ultrasound meets Light and Tracking", at HITACHI Central Research Laboratory, Tokyo, Japan, 2015.

I3. H. K. Zhang, "Development of Advanced Medical Ultrasound Imaging Ultrasound meets Light and Tracking", at Nara Institute of Science and Technology, Nara, Japan, 2015.

I2. H. K. Zhang, "Coded Excitation for Frame Rate and SNR Enhancement for Multispectral Photoacoustic Imaging ", CK (Canon-Kyoto Univ.) project visit at University of Texas at Austin, Austin, TX, 2013.

I1. H. K. Zhang, "Coded Excitation for Frame Rate and SNR Enhancement for Multispectral Photoacoustic Imaging", CK (Canon-Kyoto Univ.) project visit at Washington University at Saint Louis, Saint Louis, MI, 2013.

• Emad M. Boctor, Gregg Trahey, Nick Bottenus, Haichong Zhang, “Synthetic aperture ultrasound system”, Publication number: 20150359512.

• Emad M. Boctor, Iulian I. Iordachita, Xiaoyu Guo, Alexis Cheng, Haichong Zhang, Fereshteh Alamifar, “Robot assisted ultrasound system”, Publication number: 20150297177.

• Emad M. Boctor, Alexis Cheng, Xiaoyu Guo, Haichong K. Zhang, Russell H. Taylor, "Photoacoustic tracking and registration in interventional ultrasound", Publication number: 20160228090.

• System for Generating Synthetic Aperture Ultrasound Images during Needle Placement, pending.

• Photoacoustic voltage-sensitive dyes for in vivo imaging, pending.