Instructor, Radiology - Pediatric Radiology
Honors & Awards
Eta Kappa Nu Honors Society, Massachusetts Institute of Technology (2006)
ISMRM Merit Award, Magna Cum Laude, International Society for Magnetic Resonance in Medicine (2014,2013,2012)
Child Health Research Institute Grant Support Award, Child Health Research Institute (2014-2015)
ISMRM Merit Award, Summa Cum Laude, International Society for Magnetic Resonance in Medicine (2015)
W.S. Moore Young Investigator Award, International Society for Magnetic Resonance in Medicine (2015)
Boards, Advisory Committees, Professional Organizations
Trainee Member, International Society for Magnetic Resonance in Medicine (2007 - Present)
Trainee Member, Society for Cardiovascular Magnetic Resonance (2015 - Present)
Doctorate of Philosophy, Stanford University, Electrical Engineering (2013)
Master of Engineering, Massachusetts Institute of Technology, Electrical Eng & Comp Sci (2007)
Bachelor of Science, Massachusetts Institute of Technology, Electrical Eng & Comp Sci (2006)
Joseph Y. Cheng, John M. Pauly, Michael Lustig, Shreyas S. Vasanawala. "United States Patent US20140210469 A1 Nonrigid motion correction in 3d using autofocusing with localized linear translations", The Regents of the University of California, The Board of Trustees of the Leland Stanford Junior University, Jul 31, 2014
Current Research and Scholarly Interests
MRI; data acquisition & image reconstruction; motion correction; fast imaging
Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography.
2015; 45 (11): 1635-1643
Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution.To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography method for depicting abdominal arterial anatomy in young children.With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast-enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast-enhanced MR angiography studies. A radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed.Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9-5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries.Free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries in young children.
View details for DOI 10.1007/s00247-015-3384-y
View details for PubMedID 26040509
Free-breathing pediatric MRI with nonrigid motion correction and acceleration
JOURNAL OF MAGNETIC RESONANCE IMAGING
2015; 42 (2): 407-420
To develop and assess motion correction techniques for high-resolution pediatric abdominal volumetric magnetic resonance images acquired free-breathing with high scan efficiency.First, variable-density sampling and radial-like phase-encode ordering were incorporated into the 3D Cartesian acquisition. Second, intrinsic multichannel butterfly navigators were used to measure respiratory motion. Lastly, these estimates are applied for both motion-weighted data-consistency in a compressed sensing and parallel imaging reconstruction, and for nonrigid motion correction using a localized autofocusing framework. With Institutional Review Board approval and informed consent/assent, studies were performed on 22 consecutive pediatric patients. Two radiologists independently scored the images for overall image quality, degree of motion artifacts, and sharpness of hepatic vessels and the diaphragm. The results were assessed using paired Wilcoxon test and weighted kappa coefficient for interobserver agreements.The complete procedure yielded significantly better overall image quality (mean score of 4.7 out of 5) when compared to using no correction (mean score of 3.4, P < 0.05) and to using motion-weighted accelerated imaging (mean score of 3.9, P < 0.05). With an average scan time of 28 seconds, the proposed method resulted in comparable image quality to conventional prospective respiratory-triggered acquisitions with an average scan time of 91 seconds (mean score of 4.5).With the proposed methods, diagnosable high-resolution abdominal volumetric scans can be obtained from free-breathing data acquisitions. J. Magn. Reson. Imaging 2015;42:407-420.
View details for DOI 10.1002/jmri.24785
View details for Web of Science ID 000358258600019
View details for PubMedID 25329325
Fast Pediatric 3D Free-Breathing Abdominal Dynamic Contrast Enhanced MRI With High Spatiotemporal Resolution
JOURNAL OF MAGNETIC RESONANCE IMAGING
2015; 41 (2): 460-473
To develop a method for fast pediatric 3D free-breathing abdominal dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) and investigate its clinical feasibility.A combined locally low rank parallel imaging method with soft gating is proposed for free-breathing DCE MRI acquisition. With Institutional Review Board (IRB) approval and informed consent/assent, 23 consecutive pediatric patients were recruited for this study. Free-breathing DCE MRI with ∼1 mm(3) spatial resolution and a 6.5-sec frame rate was acquired on a 3T scanner. Undersampled data were reconstructed with a compressed sensing method without motion correction (FB-CS) and the proposed method (FB-LR). A follow-up respiratory-triggered acquisition (RT-CS) was performed as a reference standard. The reconstructed images were evaluated independently by two radiologists. Wilcoxon tests were performed to test the hypothesis that there was no significant difference between different reconstructions. Quantitative evaluation of contrast dynamics was also performed.The mean score of overall image quality of FB-LR was 4.0 on a 5-point scale, significantly better (P < 0.05) than FB-CS reconstruction (mean score 2.9), and similar to RT-CS (mean score 4.1). FB-LR also matched the temporal fidelity of contrast dynamics with a root mean square error less than 5%.Fast 3D free-breathing DCE MRI with high scan efficiency and image quality similar to respiratory-triggered acquisition is feasible in a pediatric clinical setting.J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.
View details for DOI 10.1002/jmri.24551
View details for Web of Science ID 000348850600022
Nonrigid Autofocus Motion Correction for Coronary MR Angiography with a 3D Cones Trajectory
MAGNETIC RESONANCE IN MEDICINE
2014; 72 (2): 347-361
To implement a nonrigid autofocus motion correction technique to improve respiratory motion correction of free-breathing whole-heart coronary magnetic resonance angiography acquisitions using an image-navigated 3D cones sequence.2D image navigators acquired every heartbeat are used to measure superior-inferior, anterior-posterior, and right-left translation of the heart during a free-breathing coronary magnetic resonance angiography scan using a 3D cones readout trajectory. Various tidal respiratory motion patterns are modeled by independently scaling the three measured displacement trajectories. These scaled motion trajectories are used for 3D translational compensation of the acquired data, and a bank of motion-compensated images is reconstructed. From this bank, a gradient entropy focusing metric is used to generate a nonrigid motion-corrected image on a pixel-by-pixel basis. The performance of the autofocus motion correction technique is compared with rigid-body translational correction and no correction in phantom, volunteer, and patient studies.Nonrigid autofocus motion correction yields improved image quality compared to rigid-body-corrected images and uncorrected images. Quantitative vessel sharpness measurements indicate superiority of the proposed technique in 14 out of 15 coronary segments from three patient and two volunteer studies.The proposed technique corrects nonrigid motion artifacts in free-breathing 3D cones acquisitions, improving image quality compared to rigid-body motion correction. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
View details for DOI 10.1002/mrm.24924
View details for Web of Science ID 000339714900006
Nonrigid motion correction in 3D using autofocusing withlocalized linear translations
MAGNETIC RESONANCE IN MEDICINE
2012; 68 (6): 1785-1797
MR scans are sensitive to motion effects due to the scan duration. To properly suppress artifacts from nonrigid body motion, complex models with elements such as translation, rotation, shear, and scaling have been incorporated into the reconstruction pipeline. However, these techniques are computationally intensive and difficult to implement for online reconstruction. On a sufficiently small spatial scale, the different types of motion can be well approximated as simple linear translations. This formulation allows for a practical autofocusing algorithm that locally minimizes a given motion metric--more specifically, the proposed localized gradient-entropy metric. To reduce the vast search space for an optimal solution, possible motion paths are limited to the motion measured from multichannel navigator data. The novel navigation strategy is based on the so-called "Butterfly" navigators, which are modifications of the spin-warp sequence that provides intrinsic translational motion information with negligible overhead. With a 32-channel abdominal coil, sufficient number of motion measurements were found to approximate possible linear motion paths for every image voxel. The correction scheme was applied to free-breathing abdominal patient studies. In these scans, a reduction in artifacts from complex, nonrigid motion was observed.
View details for DOI 10.1002/mrm.24189
View details for Web of Science ID 000311398600012
View details for PubMedID 22307933
Fast Concomitant Gradient Field and Field Inhomogeneity Correction for Spiral Cardiac Imaging
MAGNETIC RESONANCE IN MEDICINE
2011; 66 (2): 390-401
Non-Cartesian imaging provides many advantages in terms of flexibility, functionality, and speed. However, a major drawback to these imaging methods is off-resonance distortion artifacts. These artifacts manifest as blurring in spiral imaging. Common techniques that remove the off-resonance field inhomogeneity distortion effects are not sufficient, because the high order concomitant gradient fields are nontrivial for common imaging conditions, such as imaging 5 cm off isocenter in an 1.5 T scanner. Previous correction algorithms are either slow or do not take into account the known effects of concomitant gradient fields along with the field inhomogeneities. To ease the correction, the distortion effects are modeled as a non-stationary convolution problem. In this work, two fast and accurate postgridding algorithms are presented and analyzed. These methods account for both the concomitant field effects and the field inhomogeneities. One algorithm operates in the frequency domain and the other in the spatial domain. To take advantage of their speed and accuracy, the algorithms are applied to a real-time cardiac study and a high-resolution cardiac study. Both of the presented algorithms provide for a practical solution to the off-resonance problem in spiral imaging.
View details for DOI 10.1002/mrm.22802
View details for Web of Science ID 000293256800010
View details for PubMedID 21384423