Comparison of image quality of subtracted and nonsubtracted breath hold VIBE and free breathing GRASP in the evaluation of renal masses.

OBJECTIVE: To compare the image quality of subtracted and nonsubtracted images obtained using volumetric interpolated breath-hold exam (VIBE) and free breathing T1 weighted Golden-angle Radial Sparse Parallel (GRASP). METHODS: We retrospectively evaluated 27 consecutive patients who underwent MRI for the evaluation of renal masses. Contrast enhanced VIBE and free breathing GRASP imaging were performed, and subtraction images generated. Two radiologists performed quantitative and qualitative evaluations of image quality of nonsubtracted and subtracted data sets. Statistical analysis was performed using the Wilcoxon signed-rank test, paired t-test and kappa statistics. RESULTS: VIBE images scored statistically higher for the following parameters in the coronal and axial plane: sharpness, streak artifact, image noise, and overall image quality for standard and subtracted images (all P values P < 0.001). GRASP images had significantly less subtraction artifact in the coronal (P = 0.042) plane with a similar trend in the axial plane (P = 0.079). Interreader Kappa values for qualitative images scores were fair to good (0.23-0.71). Quantitative subtracted GRASP images had significant less subtraction artifact compared to VIBE in the anterior-posterior (3.9 mm SD 2.6 mm versus 5.8 mm SD 3.6 mm, P = 0.010), and craniocaudal direction (4.4 mm SD 2.9 mm versus 7.0 mm SD 5.3 mm, P = 0.010); a trend was seen in the left-right direction (2.6 mm SD 1.4 mm versus 4.0 mm SD 3.9 mm, P = 0.084). CONCLUSION: VIBE images have significantly better image quality than free breathing GRASP images, however free breathing GRASP images have significantly less subtraction artifact.

A Case-based Review of Abdominal (and a Few Thoracic) Emergencies and Urgencies Using Single-shot MR.

The rapid evolution of MR scanners and pulse sequence design brings an ever-expanding arsenal of diagnostic tools to radiology departments. However, this increasing abundance of diagnostic tools accentuates the challenge of using new technology efficiently and wisely-that is, to employ what may help diagnosis and/or management, but discards what has a poor likelihood of aiding patient care. This article aims to highlight practical points regarding MR pulse sequences for the evaluation of common emergencies in body imaging through case examples.