The Effect of Rectal Distention on the Intravoxel Incoherent Motion Parameters: Using Sonography Transmission Gel.

Objective: To compare the intravoxel incoherent motion (IVIM) parameters of rectal tumors before and after lumen distension obtained with sonography transmission gel.

Methods: Twenty-five patients were enrolled. The multiple b values of IVIM including 0, 20, 50, 100, 150, 200, 400, 600, 800, 1000, 1500, and 2000 s/mm. Two blinded readers have drawn the region of interests and calculated the D, D*, and f values. Interobserver variability between the 2 readers was measured by intraclass correlation coefficients and Altman-Bland plots. The intergroup differences of the average values were compared with the paired sample t test.

Results: After distention, the interrater agreement of the D* value increased obviously (from 0.547 to 0.692) and that of the D and f values increased slightly (from 0.731 and 0.618 to 0.807 and 0.666). The difference in the D value had statistical significance (P = 0.0043).

Conclusions: Intraluminal distension can increase the repeatability of IVIM parameters and the value of IVIM.