Search

Background: Long acquisition times and motion sensitivity limit T 2 mapping in the abdomen. Accelerated mapping at 3 T may allow for quantitative assessment of diffuse pancreatic disease in patients during free-breathing., Purpose: To test the feasibility of respiratory-triggered quantitative T 2 analysis in the pancreas and correlate T 2 -values with age, body mass index, pancreatic location, main pancreatic duct dilatation, and underlying pathology., Study Type: Retrospective single-center pilot study., Population: Eighty-eight adults., Field Strength/sequence: Ten-fold accelerated multiecho-spin-echo 3 T MRI sequence to quantify T 2 at 3 T., Assessment: Two radiologists independently delineated three regions of interest inside the pancreatic head, body, and tail for each acquisition. Means and standard deviations for T 2 values in these regions were determined. T 2 -value variation with demographic data, intraparenchymal location, pancreatic duct dilation, and underlying pancreatic disease was assessed., Statistical Tests: Interreader reliability was determined by calculating the interclass coefficient (ICCs). T 2 values were compared for different pancreatic locations by analysis of variance (ANOVA). Interpatient associations between T 2 values and demographical, clinical, and radiological data were calculated (ANOVA)., Results: The accelerated T 2 mapping sequence was successfully performed in all participants (mean acquisition time, 2:48 ± 0:43 min). Low T 2 value variability was observed across all patients (intersubject) (head: 60.2 ± 8.3 msec, body: 63.9 ± 11.5 msec, tail: 66.8 ± 16.4 msec). Interreader agreement was good (ICC, 0.82, 95% confidence interval: 0.77-0.86). T 2 -values differed significantly depending on age (P < 0.001), location (P < 0.001), main pancreatic duct dilatation (P < 0.001), and diffuse pancreatic disease (P < 0.03)., Data Conclusion: The feasibility of accelerated T 2 mapping at 3 T in moving abdominal organs was demonstrated in the pancreas, since T 2 values were stable and reproducible. In the pancreatic parenchyma, T 2 -values were significantly dependent on demographic and clinical parameters., Level of Evidence: 4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:410-416., (© 2019 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.)

Background: To test the hypothesis that intervals with superior beat-to-beat coronary artery repositioning precision exist in the cardiac cycle, to design a coronary MR angiography (MRA) methodology in response, and to ascertain its performance., Methods: Coronary repositioning precision in consecutive heartbeats was measured on x-ray coronary angiograms of 17 patients and periods with the highest repositioning precision were identified. In response, the temporal order of coronary MRA pulse sequence elements required modification and the T2 -prep now follows (T2 -post) rather than precedes the imaging part of the sequence. The performance of T2 -post was quantitatively compared (signal-to-noise [SNR], contrast-to-noise [CNR], vessel sharpness) to that of T2 -prep in vivo., Results: Coronary repositioning precision is <1 mm at peak systole and in mid diastole. When comparing systolic T2 -post to diastolic T2 -prep, CNR and vessel sharpness remained unchanged (both P = NS) but SNR for muscle and blood increased by 104% and 36% (both P < 0.05), respectively., Conclusion: Windows with improved coronary repositioning precision exist in the cardiac cycle: one in peak systole and one in mid diastole. Peak-systolic imaging necessitates a re-design of conventional coronary MRA pulse sequences and leads to image quality very similar to that of conventional mid-diastolic data acquisition but improved SNR., (© 2014 Wiley Periodicals, Inc.)