Faculty Bibliography

Positron Emission Tomography and Compute Tomography (PET/CT) is routinely used in evaluation for cancer staging and assessment of metastatic disease. In addition, MRI is used as a problem solving tool. Until recently PET and MR examinations have been performed by separate PET and MR devices with temporal delay between these two types of acquisitions. However, recent introduction of hybrid PET/MR systems has made it possible to acquire PET and MRI data either simultaneously or near simultaneously. PET/MR is a powerful tool that provides opportunity for multiparametric PET and MR imaging. This has tremendous potential in cancer staging, detection of metastatic disease, and assessment of treatment response. However, to take advantage of this powerful tool and implement it in clinical practice requires understanding of various components of the system, what the system can and can't do, and how to optimize protocols to answer clinically relevant questions. Some of these areas of opportunities and challenges include: (1) PET/MR: System and workflow considerations such as-Attenuation correction with MRI-Validation of PET/MR with respect to PET/CT-Whole body and targeted organ protocol (2) Current and potential clinical indications for oncologic imaging such as-Lymphoma Imaging-Simultaneous locodistant staging for cancers-Assessment of treatment response (3) Limitations of PET/MR such as-Lung imaging-Osseous lesions

Purpose To develop a three-dimensional breath-hold (BH) magnetic resonance (MR) cholangiopancreatographic protocol with sampling perfection with application-optimized contrast using different flip-angle evolutions (SPACE) acquisition and sparsity-based iterative reconstruction (SPARSE) of prospectively sampled 5% k-space data and to compare the results with conventional respiratory-triggered (RT) acquisition. Materials and Methods This HIPAA-compliant prospective study was institutional review board approved. Twenty-nine patients underwent conventional RT SPACE and BH-accelerated SPACE acquisition with 5% k-space sampling at 3 T. Spatial resolution and other parameters were matched when possible. BH SPACE images were reconstructed by enforcing joint multicoil sparsity in the wavelet domain (SPARSE-SPACE). Two board-certified radiologists independently evaluated BH SPARSE-SPACE and RT SPACE images for image quality parameters in the pancreatic duct and common bile duct by using a five-point scale. The Wilcoxon signed-rank test was used to compare BH SPARSE-SPACE and RT SPACE images. Results Acquisition time for BH SPARSE-SPACE was 20 seconds, which was significantly (P < .001) shorter than that for RT SPACE (mean +/- standard deviation, 338.8 sec +/- 69.1). Overall image quality scores were higher for BH SPARSE-SPACE than for RT SPACE images for both readers for the proximal, middle, and distal pancreatic duct, but the difference was not statistically significant (P > .05). For reader 1, distal common bile duct scores were significantly higher with BH SPARSE-SPACE acquisition (P = .036). More patients had acceptable or better overall image quality (scores >/= 3) with BH SPARSE-SPACE than with RT SPACE acquisition, respectively, for the proximal (23 of 29 [79%] vs 22 of 29 [76%]), middle (22 of 29 [76%] vs 18 of 29 [62%]), and distal (20 of 29 [69%] vs 13 of 29 [45%]) pancreatic duct and the proximal (25 of 28 [89%] vs 22 of 28 [79%]) and distal (25 of 28 [89%] vs 24 of 28 [86%]) common bile duct. Conclusion BH SPARSE-SPACE showed similar or superior image quality for the pancreatic and common duct compared with that of RT SPACE despite 17-fold shorter acquisition time. (c) RSNA, 2016.

PURPOSE: To investigate the feasibility of high temporal resolution quantitative perfusion imaging of bladder tumors performed simultaneously with conventional multi-phase MR urography (MRU) using a novel free-breathing continuously acquired radial MRI sequence with compressed-sensing reconstruction. METHODS: 22 patients with bladder lesions underwent MRU using GRASP (Golden-angle RAdial Sparse Parallel) acquisition. Multi-phase contrast-enhanced abdominopelvic GRASP was performed during free-breathing (1.4x1.4x3.0mm3 voxel size; 3:44min acquisition). Two dynamic datasets were retrospectively reconstructed by combining different numbers of sequentially acquired spokes into each dynamic frame: 110 spokes per frame for 25-second temporal resolution (serving as conventional MRU for clinical interpretation) and 8 spokes per frame for 1.7-second resolution. Using 1.7-second resolution images, ROIs were placed within bladder lesions and normal bladder wall, a femoral artery arterial input function was generated, and the Generalized Kinetic Model was applied. RESULTS: Biopsy/cystectomy demonstrated 16 bladder tumors (13 stage>/=T2, 3 stage/=T2 than stage