Effects of different breathing techniques on the IVIM-derived quantitative parameters of the normal pancreas

To prospectively compare the differences in intravoxel incoherent motion (IVIM)-derived quantitative parameters in different anatomic locations of the normal pancreas with different breathing techniques in a healthy population.

Twenty-six volunteers successfully underwent pancreas axial IVIM imaging with a 3.0-T MR system using 11 b-values (from 0 to 1000 sec/mm²) with three different breathing techniques: free breath (FB), liver dome scout (LDS), and phase scout (PS). The IVIM-derived quantitative parameters in three anatomic locations (head, body, and tail of the pancreas) were calculated. The intra-, inter-, and short-term consistency of IVIM-derived quantitative parameters were assessed by comparing 95% confidence interval (CI) of limits of agreement (LOA) of difference between measurements and clinical maximum allowed difference using the Bland-Altman method. The Kruskal-Wallis test was used to compare pancreatic IVIM-derived parameters.

In Bland-Altman graph, the maximum values of the 95% CIs of LOAs of D_slow, D_fast, and f were (0.123 ± 0.022) × 10^-3 mm²/sec, (22.093 ± 4.997) × 10^-3 mm²/sec, and (3.942 ± 0.621)%, and the consistency of D_slow and f was good and that of D_fast was poor overall. The D_slow, D_fast, and f values of normal pancreas were (1.056 ± 0.121) × 10^-3 mm²/sec, (55.755 ± 13.011) × 10^-3 mm²/sec, and (26.036 ± 2.361)%, respectively, and there aren't any breathing technique (P > 0.05) or location (P > 0.05) dependent differences.

Our study shows that IVIM-derived quantitative parameters of the pancreas may not be affected by breathing techniques and anatomic locations. The f and D_slow values have good repeated measurement consistency under different breathing techniques.