Faculty Bibliography

The original version of this article contained an error in author name. The co-author's name was published as Ivan M. Pedrosa, instead it should be Ivan Pedrosa. The original article has been corrected.

PURPOSE/OBJECTIVE:-weighted images from a single scan and allows for free-breathing acquisition. THEORY AND METHODS/UNASSIGNED:-weighted gradient-echo (GRE) data. Improved robustness is achieved by extracting a respiratory signal from the GRE data and using it for motion-weighted reconstruction. RESULTS:-weighted Dixon acquisition is possible. CONCLUSION/CONCLUSIONS:-weighted imaging in a single scan. In addition to free-breathing abdominal examination, it promises value for clinical applications that are frequently affected by motion artifacts.

INTRODUCTION/BACKGROUND:-weighted DCE-MRI. MATERIALS AND METHODS/METHODS:) and arterial input function (AIF). In addition, the effect of the conversion method on the diagnostic accuracy was evaluated with 36 breast lesions (19 benign and 17 malignant). RESULTS:. CONCLUSION/CONCLUSIONS:measurement is not available and a low FA is used for DCE-MRI, the uncertainty in the contrast kinetic parameter estimation can be reduced by using the LC method with pAIF, without compromising the diagnostic accuracy.

The disease-focused panel (DFP) program was created by the Society of Abdominal Radiology (SAR) as a mechanism to "improve patient care, education, and research" in a "particular disease or a particular aspect of a disease". The DFP on renal cell carcinoma (RCC) was proposed in 2014 and has been functional for 4 years. Although nominally focused on RCC, the scope of the DFP has included indeterminate renal masses because many cannot be assigned a specific diagnosis when detected. Since its founding, the DFP has been active in a variety of clinical, research, and educational projects to optimize the care of patients with known or suspected RCC. The DFP is utilizing multi-institutional and cross-disciplinary collaboration to differentiate benign from malignant disease, optimize the management of early stage RCC, and ultimately to differentiate indolent from aggressive cancers. Several additional projects have worked to develop a quantitative biomarker that predicts metastatic RCC response to anti-angiogenic therapy. While disease focus is the premise by which all DFPs are created, it is likely that in the future the RCC DFP will need to expand or create new panels that will focus on other specific aspects of RCC-a result that the program's founders envisioned. New knowledge creates a need for more focus.

PET imaging (PET/CT) is routinely used in evaluation of patients with various malignancies including lymphoma. Many of these patients also undergo a separate MRI examination as a problem solving tool. These PET (PET/CT) and MRI examinations are usually performed with temporal delay (at a different time and date). Introduction of hybrid PET/MR systems over the last 5 to 10 years now enables simultaneous or near simultaneous acquisition of PET and MRI information. The role of hybrid PET/MRI is being investigated by many groups in various oncologic applications such as cancer detection, staging, and assessment of treatment response. These hybrid PET/MR systems provide not only metabolic PET information but multi-parametric MRI information (such as diffusion and perfusion weighted imaging) which is temporally and spatially correlated. To test, validate, and clinically implement these systems and to take advantage of all of its various capabilities and functionalities we need to understand: - different components of the system and how they have been modified from conventional PET and M

PURPOSE: To develop and evaluate a novel dynamic contrast-enhanced imaging technique called RACER-GRASP (Respiratory-weighted, Aortic Contrast Enhancement-guided and coil-unstReaking Golden-angle RAdial Sparse Parallel) MRI that extends GRASP to include automatic contrast bolus timing, respiratory motion compensation, and coil-weighted unstreaking for improved imaging performance in liver MRI. METHODS: In RACER-GRASP, aortic contrast enhancement (ACE) guided k-space sorting and respiratory-weighted sparse reconstruction are performed using aortic contrast enhancement and respiratory motion signals extracted directly from the acquired data. Coil unstreaking aims to weight multicoil k-space according to streaking artifact level calculated for each individual coil during image reconstruction, so that coil elements containing a high level of streaking artifacts contribute less to the final results. Self-calibrating GRAPPA operator gridding was applied as a pre-reconstruction step to reduce computational burden in the subsequent iterative reconstruction. The RACER-GRASP technique was compared with standard GRASP reconstruction in a group of healthy volunteers and patients referred for clinical liver MR examination. RESULTS: Compared with standard GRASP, RACER-GRASP significantly improved overall image quality (average score: 3.25 versus 3.85) and hepatic vessel sharpness/clarity (average score: 3.58 versus 4.0), and reduced residual streaking artifact level (average score: 3.23 versus 3.94) in different contrast phases. RACER-GRASP also enabled automatic timing of the arterial phases. CONCLUSIONS: The aortic contrast enhancement-guided sorting, respiratory motion suppression and coil unstreaking introduced by RACER-GRASP improve upon the imaging performance of standard GRASP for free-breathing dynamic contrast-enhanced MRI of the liver. Magn Reson Med, 2017. (c) 2017 International Society for Magnetic Resonance in Medicine.

PURPOSE: Golden-angle radial sparse parallel (GRASP) MRI reconstruction requires gridding and regridding to transform data between radial and Cartesian k-space. These operations are repeatedly performed in each iteration, which makes the reconstruction computationally demanding. This work aimed to accelerate GRASP reconstruction using self-calibrating GRAPPA operator gridding (GROG) and to validate its performance in clinical imaging. METHODS: GROG is an alternative gridding approach based on parallel imaging, in which k-space data acquired on a non-Cartesian grid are shifted onto a Cartesian k-space grid using information from multicoil arrays. For iterative non-Cartesian image reconstruction, GROG is performed only once as a preprocessing step. Therefore, the subsequent iterative reconstruction can be performed directly in Cartesian space, which significantly reduces computational burden. Here, a framework combining GROG with GRASP (GROG-GRASP) is first optimized and then compared with standard GRASP reconstruction in 22 prostate patients. RESULTS: GROG-GRASP achieved approximately 4.2-fold reduction in reconstruction time compared with GRASP ( approximately 333 min versus approximately 78 min) while maintaining image quality (structural similarity index approximately 0.97 and root mean square error approximately 0.007). Visual image quality assessment by two experienced radiologists did not show significant differences between the two reconstruction schemes. With a graphics processing unit implementation, image reconstruction time can be further reduced to approximately 14 min. CONCLUSION: The GRASP reconstruction can be substantially accelerated using GROG. This framework is promising toward broader clinical application of GRASP and other iterative non-Cartesian reconstruction methods. Magn Reson Med, 2017. (c) 2017 International Society for Magnetic Resonance in Medicine.

BACKGROUND:Diffusion-weighted imaging (DWI) provides insight into the pathophysiology underlying renal dysfunction. Variants of DWI include intravoxel incoherent motion (IVIM), which differentiates between microstructural diffusion and vascular or tubular flow, and diffusion tensor imaging (DTI), which quantifies diffusion directionality. PURPOSE/OBJECTIVE:To investigate the reproducibility of joint IVIM-DTI and compare controls to presurgical renal mass patients. STUDY TYPE/METHODS:Prospective cross-sectional. SUBJECTS/METHODS:Thirteen healthy controls and ten presurgical renal mass patients were scanned. Ten controls were scanned twice to investigate reproducibility. FIELD STRENGTH/SEQUENCE/UNASSIGNED:Subjects were scanned on a 3T system using 10 b-values and 20 diffusion directions for IVIM-DTI in a study approved by the local Institutional Review Board. ASSESSMENT/RESULTS:Retrospective coregistration and measurement of joint IVIM-DTI parameters were performed. STATISTICAL ANALYSIS/METHODS:Parameter reproducibility was defined as intraclass correlation coefficient (ICC) >0.7 and coefficient of variation (CV) <30%. Patient data were stratified by lesion side (contralateral/ipsilateral) for comparison with controls. Corticomedullary differentiation was evaluated. RESULTS:In controls, the reproducible subset of REnal Flow and Microstructure AnisotroPy (REFMAP) parameters had average ICC = 0.82 and CV = 7.5%. In renal mass patients, medullary fractional anisotropy (FA) was significantly lower than in controls (0.227 ± 0.072 vs. 0.291 ± 0.044, P = 0.016 for the kidney contralateral to the mass and 0.228 ± 0.070 vs. 0.291 ± 0.044, P = 0.018 for the kidney ipsilateral). In the kidney ipsilateral to the mass, cortical Dp,radial was significantly higher than in controls (P = 0.012). Conversely, medullary Dp,axial was significantly lower in contralateral than ipsilateral kidneys (P = 0.027) and normal controls (P = 0.044). DATA CONCLUSION/UNASSIGNED:REFMAP-MRI parameters provide unique information regarding renal dysfunction. In presurgical renal mass patients, directional flow changes were noted that were not identified with IVIM analysis alone. Both contralateral and ipsilateral kidneys in patients show reductions in structural diffusivities and anisotropy, while flow metrics showed opposing changes in contralateral vs. ipsilateral kidneys. LEVEL OF EVIDENCE/METHODS:2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

OBJECTIVE:To describe novel 3-dimensional (3D) printing and augmented reality (AR) methods of image data visualization to facilitate anatomic understanding and to assist with surgical planning and decision-making during robotic partial nephrectomy. MATERIALS AND METHODS/METHODS:We created a video of the workflow for creating 3D printed and AR kidney models along with their application to robotic partial nephrectomy. Key steps in their development are (1) radiology examination (magnetic resonance imaging and computed tomography), (2) image segmentation, (3) preparing for 3D printing or AR, and (4) printing the model or deploying the model to the AR device. RESULTS:We demonstrate the workflow and utility of 3D printing and AR kidney models applied to a case of a 70-year-old woman with a 3.4 cm renal mass on her left pelvic kidney. A 3D printed kidney model was created using multicolor PolyJet technology (Stratasys J750), allowing a transparent kidney with coloring of the renal tumor, artery, vein, and ureter. An AR kidney model was created using Unity 3D software and deployed to a Microsoft HoloLens. The 3D printed and AR models were used preoperatively and intraoperatively to assist in robotic partial nephrectomy. To date, we have created 15 3D printed and AR kidney models to use for robotic partial nephrectomy planning and intraoperative guidance. The application of 3D printed and AR models is safe and feasible and can influence surgical decisions. CONCLUSION/CONCLUSIONS:Our video highlights the workflow and novel application of 3D printed and AR kidney models to provide preoperative guidance for robotic partial nephrectomy. The insights gained from advanced visualization can influence surgical planning decisions.

Purpose: There is limited data regarding how many cycles of chemotherapy are optimal prior to debulking surgery in metastatic ovarian cancer. Furthermore, early identification of non-responders would prompt discontinuation of chemotherapy and earlier surgical management. The purpose of our study was to investigate the performance of FDG PET, dynamic contrast-enhanced (DCE) and intra-voxel incoherent motion (IVIM) MR as early predictors of treatment response in ovarian cancer. Parametric images of molecular diffusion restriction (D), tissue perfusion (D[asterisk]), vascular volume fraction (F), blood->interstitium constant of transfer (Ktrans), interstitum->plasma constant of transfer (Kep), extravascular/extracellular volume % (Ve) and plasma volume % (Ve) were investigated along with routine measures of SUV and ADC. Materials & Methods: Five subjects with a new diagnosis of epithelial ovarian cancer enrolled in the study. All subjects underwent 3 cycles of standardized chemotherapy followed by cytoreduction (debulking surgery). FDG PET/MR including DCE and IVIM was performed at baseline (T1), after cycle 1 (T2) and after cycle 3 (T3) of chemotherapy. Final responses were categorized at T3 by RECIST 1.1. Olea 3.0 software was used to generate parametric images from the multi-B-value DWI and DCE-MR datasets at all three timepoints. Parametric DICOM images were then coregistered to anatomical datasets using MIMvista and fusion was manually adjusted to optimize co-registration of tumor lesions across the multiple datasets. VOIs were manually drawn on clearly visible solid tumor deposits on PET, DCE-MR and DWI MR images. The parametric images derived from IVIM and DCE-MR at T2 were analyzed as early predictors of final response. Results: Five subjects completed FDG PET and IVIM-MR, three of which underwent DCE-MR. All subjects were partial responders by RECIST at T3. SUV values were only available for 4/5 patients due to technical difficulties and DCE-MR was only available for 3/5. All 5 subjects had good IVIM data. At T2, the SUVmax decreased on average by -39% across all subjects (p<0.001) and the SUVmean decreased on average by -43% across all subjects (p<0.001). At T2, the ADCmean increased on average by +25% across all subjects (p<0.05). At T2, the molecular diffusion restriction (D) increased on average by +43% across all subjects, approaching statistical significance (p=0.058). Furthermore, D[asterisk], F, Kep, Ktrans, and Vp increased in some subjects and decreased in others, without any recognizable pattern. Ve decreased in 3/3 patients, however, not reaching statistical significance. Conclusions: In this current FDG PET/MR study of ovarian cancer, SUVmax and ADCmean values obtained after one cycle of chemotherapy were consistently associated with partial anatomical treatment responses at end of therapy. These findings are in agreement with pre-existing literature studying the value of SUV and ADC in early treatment response assessment. Only one of seven advanced perfusion/diffusion metrics (D; molecular diffusion restriction) was reliably associated with treatment response. This finding that D is associated with treatment response is not surprising given that it is based on ADC without the contribution of intravascular diffusion. Our current small dataset does not yet demonstrate the value of the remaining analyzed advanced DCE-MR and DWI parameters. Further study is required to determine the utility of DCE- and IVIM-derived parameters in early response assessment. Voxelwise correlative studies and other advanced data processing methods are underway to determine if these advanced quantitative parameters may provide further information in the early assessment of chemotherapy treatment response. (Table Presented)