Objective: Determine normal T1 and extracellular volume (ECV) of the pancreas in subjects with no pancreas disease and correlate with age and gender.
Subjects and methods: We imaged 120 healthy subjects (age range 20-78 years) who are on annual screening with MRI/MRCP for the possibility of pancreatic cancer. Subjects had a predisposition to develop pancreatic cancer, but no history of pancreas disease or acute symptoms. Equal number (n = 60) of subjects were scanned on either 1.5 T or 3 T scanner using dual flip angle spoiled gradient echo technique incorporating fat suppression and correction for B1 field inhomogeneity. Optimization of imaging parameters was performed using a T1 phantom. ECV was calculated using pre- and post-contrast T1 of the pancreas and plasma. Regression analysis and Mann-Whitney tests were used for statistical analysis.
Results: Median T1 on 1.5 T was 654 ms (IQR 608-700); median T1 on 3 T was 717 ms (IQR 582-850); median ECV on 1.5 T was 0.28 (IQR 0.21-0.33), and median ECV on 3 T was 0.25 (IQR 0.19-0.28). Age had a mild positive correlation with T1 (r = 0.24, p = 0.009), but not with ECV (r = 0.06, p = 0.54). T1 and ECV were similar in both genders (p > 0.05).
Conclusion: This study measured the median T1 and ECV of the pancreas in subjects with no pancreas disease. Pancreas shows longer T1 relaxation times in older population, whereas extracellular fraction remains unchanged. Median T1 values were different between two magnet strengths; however, no difference was seen between genders and ECV fractions.
Keywords: Extracellular volume; MRI; Pancreas; Quantitative imaging; T 1 relaxometry.