Patient respiratory-triggered quantitative T 2 mapping in the pancreas.

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.)