Sandy Napel

My primary interests are in developing diagnostic and therapy-planning applications and strategies for the acquisition and visualization of multi-dimensional medical imaging data. Examples are: creation of three-dimensional images of blood vessels using CT, visualization of complex flow within blood vessels using MR, computer-aided detection and characterization of lesions (e.g., colonic polyps, pulmonary nodules) from cross-sectional image data, visualization and automated assessment of 4D ultrasound data, and fusion of images acquired using different modalities (e.g., CT and MR). I have also been involved in developing and evaluating techniques for exploring cross-sectional imaging data from an internal perspective, i.e., virtual endoscopy (including colonoscopy, angioscopy, and bronchoscopy), and in the quantitation of structure parameters, e.g., volumes, lengths, medial axes, and curvatures. Finally, I am also interested in creating workable solutions to the problem of "data explosion," i.e., how to look at the thousands of images generated per examination using modern CT and MR scanners.

More recently, we have started a group called ISIS (Information Sciences in Imaging @ Stanford) whose mission is to advance the clinical and basic sciences in radiology, while improving our understanding of biology and the manifestations of disease, by pioneering methods in the information sciences that integrate imaging, clinical and molecular data. More later...

Peer-reviewed Representative Publications (of 90 in press)

Visualization

S. Napel, M.P. Marks, G.D. Rubin, R.B. Jeffrey, M.D. Dake, D.R. Enzmann, C.H. McDonnell, S.M. Song: "CT Angiography Using Spiral CT and Maximum Intensity Projections." Radiology, 185(2):607-610, 1992.

S. Napel, G.D. Rubin, R.B. Jeffrey, Jr.: "STS-MIP: A New Reconstruction Technique for CT of the Chest." J Comput Assist Tomogr, 17(5):832-838, 1993.

R. Raman, S. Napel, C. F. Beaulieu, E. S. Bain, R. B. Jeffrey Jr., G. D. Rubin, “Automated Generation of Curved Planar Reformations from Volume Data: Method and Evaluation,” Radiology, 223 (1):275-80, 2002.

R. Raman, S. Napel, G.D. Rubin, “Curved Slab Maximum Intensity Projections: Method and Evaluation,” Radiology, 229(1):255-60, 2003.

A. Sherbondy, M. Houston, S. Napel, “Fast Volume Segmentation with Simultaneous Visualization Using Programmable Graphics Hardware,” Proceedings: IEEE Visualization, 171-176, 2003.

A. Quon, S. Napel, C. F. Beaulieu, S. S. Gambhir, ““Flying Through” and “Flying Around” a PET/CT Scan: Pilot Study And Development Of 3D Integrated 18F-FDG PET/CT Scanning for Virtual Bronchoscopy And Colonoscopy,” J Nucl Med 47:1081-1087, 2006.

R. Shi , S. Napel, J.K. Rosenberg, L.K. Shin, C.B. Freeman , M.A. Mogensen, A.J. Joshi, P. Pankhudi, C.F. Beaulieu, “Transparent Rendering of Intraluminal Contrast for 3D Polyp Visualization at CT Colonography,” J Comput Assist Tomogr. 31(5):773-9, 2007.

T. Rakshe, D. Fleischmann , J. Rosenberg, J. Roos, S. Napel, “Knowledge-Based Interpolation of Curves: Application to Femoropopliteal Arterial Centerline,” Med Image Anal. 11(2):157-68, 2007.

D. N. Tran, D. Fleischmann, T. Rakshe, J. E. Roos, J. Rosenberg, M. Straka, S. Napel, “Femoropopliteal Artery Centerline Interpolation using Contralateral Shape,” Medical Physics 34(9):3428-35, 2007.

Segmentation

S. Shiffman, G. D. Rubin, P. Schraedley-Desmond, S. Napel, “Semiautomated Segmentation of Blood Vessels using Ellipse Overlap Criteria: Method and Comparison to Manual Editing,” Medical Physics 30(10): 2572-83, 2003.

F. Zhuge, S. Sun, G.D. Rubin, S. Napel, “An Abdominal Aortic Aneurysm Segmentation Method: Level Set with Region and Statistical Information,” Medical Physics 33(5):1440-1453, May 2006.

R. Raman, B. Raman, S. Napel, G. D. Rubin, “Improved Speed of Bone Removal in CT Angiography (CTA) Using Automated Targeted Morphological Separation: Method and Evaluation in CTA of Lower Extremity Occlusive Disease,” J Comput Assist Tomogr. 32(3):485-91, 2008.

Virtual Endoscopy

D.S. Paik, C.F. Beaulieu, R.B. Jeffrey, Jr., G.D. Rubin, S. Napel, "Automated Flight Path Planning for Virtual Endoscopy." Medical Physics 25(5):629-637, 1998.

E.L. Yuh, R.B Jeffrey, Jr., R.L. Birdwell, B.H. Chen, S. Napel, "Virtual Endoscopy Using Perspective Volume-Rendered Three-Dimensional Sonographic Data: Technique and Clinical Applications," AJR 172:1193-1197, 1999.

C.A. Karadi, C.F. Beaulieu, R.B. Jeffrey, Jr., D.S. Paik, S. Napel, "Visualization Modes for CT Colonography, Part I: Synthesis and Insertion of Polyps into Patient CT Data," Radiology 212(1):195-201, 1999.

C.F. Beaulieu, R.B. Jeffrey, Jr., C.A. Karadi, D.S. Paik, S. Napel, "Visualization Modes for CT Colonography, Part II: Blinded Comparison of Axial CT, Virtual Endoscopy, and Panoramic View Volume Rendering," Radiology 212(1):203-212, 1999.

D.S. Paik, C.F. Beaulieu, R.B. Jeffrey, Jr., C.A. Karadi, S. Napel, "Visualization Modes for CT Colonography using Cylindrical and Planar Map Projections." J Comput Assist Tomogr 24(2)179-88, 2000.

P. Li, S. Napel, B. Acar, D.S. Paik, R. B. Jeffrey, Jr., C.F. Beaulieu, “Automatic Registration of Colonic Polyps Between Supine and Prone Scans in CT Colonography,” Medical Physics 31(10):2912-23, 2004.

R. Shi, P. Schraedley-Desmond, S. Napel, E. Olcott, R. B. Jeffrey, Jr., J. Yee, M. E. Zalis, D. Margolis, D. S. Paik, A. Sherbondy, P. Sundaram, C. F. Beaulieu, "CT colonography: influence of 3D viewing and polyp candidate features on interpretation with computer-aided detection," Radiology 239(3):768-776, 2006.

Computer-aided Detection

S.B. Gokturk, C. Tomasi,B. Acar, C.F. Beaulieu, D.S. Paik, R.B. Jeffrey Jr, J. Yee, S. Napel, "A statistical 3-D pattern processing method for computer-aided detection of polyps in CT colonography," IEEE Transactions on Medical Imaging 20(12):1251-60, 2001.

B. Acar, C.F. Beaulieu, S.B. Gokturk, C. Tomasi, D.S. Paik, R.B. Jeffrey Jr, J. Yee, S. Napel, "Edge displacement field-based classification for improved detection of polyps in CT colonography," IEEE Transactions on Medical Imaging 21(12):1461-7 , 2002.

P. Sundaram, C. F. Beaulieu, D. S. Paik, P. Schraedley-Desmond, S. Napel, “CT Colonography: Does improved z resolution help computer-aided polyp detection?” Medical Physics 30(10): 2663-74, 2003.

D. S. Paik, C. F. Beaulieu, G. D. Rubin, B. Acar, R. B. Jeffrey, Jr., J. Yee, J. Dey, S. Napel, “Surface Normal Overlap: A Computer-Aided Detection Algorithm with Application to Colonic Polyps and Lung Nodules in Helical CT ” IEEE Transactions on Medical Imaging 23(6):661-675, 2004.

A. Mani, S. Napel, D. S. Paik, R. B. Jeffrey, Jr., J. Yee, E. W. Olcott, R. Prokesch, M. Davila, P. Schraedley-Desmond, C. F. Beaulieu, “CT Colonography: Feasibility of Computer-Aided Polyp Detection in a “First Reader” Paradigm,” Journal of Computer-assisted Tomography, 28:318–326, 2004.

M. Bilello, S. B. Gokturk, T. Desser, S. Napel. R. B. Jeffrey, C. F. Beaulieu, “Automatic Detection and Classification of Hypodense Hepatic Lesions on Contrast-Enhanced Venous-Phase CT,” Medical Physics 31(9) :2584-93, 2004.

G. D. Rubin, J. Lyo, D. S. Paik, A. Sherbondy, L. Chow, A. N. Leung, R. Mindelzun, S. E. Zinck, D. P. Naidich, S. Napel, “Pulmonary Nodules in MDCT Scans: Impact of Computer-aided Detection,” Radiology 234(1):274-273, 2005.

R. Shi, P. Schraedley-Desmond, S. Napel, E. Olcott, R. B. Jeffrey, Jr., J. Yee, M. E. Zalis, D. Margolis, D. S. Paik, A. Sherbondy, P. Sundaram, C. F. Beaulieu, “Computer Aided Polyp Detection in CT Colonography: Influence of 3D Viewing and Polyp Candidate Features on Interpretation,” Radiology 239(3):768-776, 2006.

S. Sun, G. D. Rubin, D.S. Paik, F. Zhuge, R. Steiner, S. Napel,  “Registration of Lung Nodules using a Semi-Rigid Model: Method and Preliminary Results,” Medical Physics, 34(2):613–626,  2007.

S. Sun, F. Zhuge, J. Rosenberg, G. D. Rubin, S. Napel,  “Learning-Enhanced Simulated Annealing: Method, Evaluation, and Application to Lung Nodule Registration,” International Journal of Applied Intelligence, 28(1):83-99, 2008.

R. Shi , S. Napel, J.K. Rosenberg, L.K. Shin, C.B. Freeman , M.A. Mogensen, A.J. Joshi, P. Pankhudi, C.F. Beaulieu, “Transparent Rendering of Intraluminal Contrast for 3D Polyp Visualization at CT Colonography,” J Comput Assist Tomogr. 31(5):773-9, 2007.

E. Konukoglu, B. Acar, D.S. Paik, C.F. Beaulieu, S. Napel, “PELS: Polyp Enhancing Level-Set Evolution of the Colon Wall,” IEEE Transactions on Medical Imaging 26(12): 1640-1656, 2007.

P. Sundaram, A. J. Zamorodian, C. F. Beaulieu, S. Napel, “Colon Polyp Detection using Smoothed Shape Operators: Preliminary Results,” Medical Image Analysis 12(2):99-199, 2008.

Quantitative Applications

G.D. Rubin, D.S. Paik, P.C. Johnson, S. Napel, "Measurement of the Aorta and its Branches using Helical CT," Radiology 206:823-829, 1998.

S. Napel, H Xu, D.S. Paik, B.A. Ross, T.S. Sumanaweera, J.A. Hossack, R.B. Jeffrey Jr., "Carotid Disease: Automated Analysis with Cardiac-gated Three dimensional US Technique and Preliminary Results," Radiology 222(2):560-3, 2002.

R. Raman, B. Raman, S. Napel, G. D. Rubin, “Semi-automated Quantification of the Mass and Distribution of Vascular Calcification using Multidetector CT: Method and Evaluation,” Radiology 247(1):241-50, 2008.

Reconstruction from Projections

S.Y. Yen, G.D. Rubin, C.H. Yan, S. Napel, "Longitudinal Aliasing in Spiral CT." IEEE Transactions on Medical Imaging, 18(1):43-58, November 1998.

S.Y. Yen, G.D. Rubin, S. Napel, "Spatially-varying Longitudinal Aliasing and Resolution in Spiral CT," Medical Physics 26(12): 2617-2625, 1999.

C.H. Yan, R.T. Whalen, G.S. Beaupre, S.Y. Yen, S. Napel, "Modeling of Polychromatic Attenuation using Computed Tomography Reconstructed Images." Medical Physics 26(4):631-642, 1999.

C.H. Yan, R.T. Whalen, G.S. Beaupre, S.Y. Yen, S. Napel, "Reconstruction Algorithm for Polychromatic CT Imaging: Application to Beam Hardening Correction." IEEE Transactions on Medical Imaging, 19(1):1-11, 2000.

D. Fleischmann, G.D. Rubin, D.S. Paik, S.Y. Yen, P.R. Hilfiker, C.F. Beaulieu, S. Napel, "Helical Stair-Step Artifacts in Single-Slice versus Multi-Slice CT," Radiology 216(1):185-96, 2000.

Book Chapters

S. Napel, "Basic Principles of Spiral CT." In Spiral CT: Principles, Techniques, and Clinical Applications, E.K. Fishman and R.B. Jeffrey, Jr., Editors, Raven Press, Ltd., New York, pp. 3-15, 1998.

S. Napel, "Principles And Techniques of 3D Spiral CT Angiography." In Spiral CT: Principles, Techniques, and Clinical Applications, E.K. Fishman and R.B. Jeffrey, Jr., Editors, Raven Press, Ltd., New York, pp. 339-360, 1998.

Beaulieu, CF, Paik, DS, Napel, S, Jeffrey, RB Jr., “Advanced 3D Display Methods,” In: Atlas of Virtual Colonoscopy, A.H. Dachman, Ed., Springer Verlag Publishers, NY, pp. 37-44, 2003.

S. Napel, “Basic Principles of MDCT,” In: Multidetector CT, Principles, Techniques, and Clinical Applications, E. Fishman and R.B. Jeffrey Jr., Eds., Lippincott Williams and Wilkins, Philadelphia, PA, pp. 3-13, 2004.

Beaulieu, CF, Paik, DS, Napel, S, Jeffrey, RB Jr., “Advanced 3D Display Methods,” In: Fundamentals of Virtual Colonoscopy, A.H. Dachman, Ed., Springer Verlag Publishers, NY, pp. 53-64, 2005.