Quantitative T2 Mapping of Acute Pancreatitis

Background: Quantification of the T2 signal by means of T2 mapping in acute pancreatitis (AP) has the potential to quantify the parenchymal edema. Quantitative T2 mapping may overcome the limitations of previously reported scoring systems for reliable assessment of AP. Purpose: To evaluate MR-derived pancreatic T2 mapping values in AP and correlate them with markers of disease severity. Study Type: Prospective single-center study. Population: 76 adults with AP (20-91 years, females/males: 39/37). Field Strength/Sequence: Fat suppressed multiecho spin-echo prototype sequence to quantify T2 signal at 3T MRI. Assessment: The severity of AP was assessed clinically, biologically, and by contrast-enhanced CT (CECT) performed 48-72 hours after symptom onset. MRI was then performed <= 24 hours after CT. Two readers blinded to any clinical information independently evaluated the T2 values by placing three regions of interest inside the pancreatic head, body, and tail on the T2 mapping MR sequence. Results were compared with corresponding CECT images as the standard and clinical severity parameters, using the length of hospital stay as our primary endpoint. Statistical Tests: Continuous variables were compared using the Spearman's rank correlation coefficient, analysis of variance (ANOVA) or Student's t-test. Results: T2 values significantly correlated with the length of hospital stay (r(s)(74) = 0.29), CT severity index (CTSI) (r(s)(73) = 0.61; CTSI 0-3: 72 +/- 14 msec, CTSI 4-10: 88 +/- 15), intensive care unit (ICU) admission (t(2.77) = -3.41) and presence of organ failure (t(6.72) = -3.42), whereas the CTSI and Ranson score were not significantly related with ICU admission (CTSI: P = 0.24; Ranson score: P = 0.24) and organ failure (CTSI: P = 0.11; Ranson score P = 0.11). Conclusion: T2 mapping correlates with AP severity parameters and is useful for assessing the severity of AP with higher sensitivity than the usual clinical and radiological scoring systems.