Clinical application of 3D VIBECAIPI-DIXON for non-enhanced imaging of the pancreas compared to a standard 2D fat-saturated FLASH

PurposeTo compare a fast 3D VIBE sequence with Dixon fat saturation and CAIPIRINHA acceleration techniques (3D VIBECAIPI-DIXON) to a standard 2D FLASH sequence with spectral fat saturation and conventional GRAPPA acceleration technique (2D FlashGRAPPA-fs) for non-enhanced imaging of the pancreas.Methods and materialsIn this retrospective, institutional review board-approved intra-individual comparison study, 29 patients (7 female, 22 male; mean age 60.4±20.9 years) examined on a 48-channel 3.0-T MR system (MAGNETOM Skyra VD 13, Siemens Healthcare Sector, Germany) were included. 3D VIBECAIPI-DIXON (TR/TE−3.95/2.5+1.27 ms; spatial resolution−1.2×1.2×3.0 mm3; CAIPIRINHA 2×2 [1], acquisition time−0:12 min) and 2D FlashGRAPPA-fs (TR/TE−195/3.69 ms; 1.2×1.2×3.0 mm3; GRAPPA 2, 3×0:21 min) sequences were performed in each subject in random order prior to the administration of an intravenous contrast agent. Two radiologists evaluated the images with regard to diagnostic preference. Semi-quantitative signal ratios were calculated for the pancreas versus the liver, spleen, muscle, and visceral fat. Inter-reader agreement was calculated using unweighted Cohen's kappa. Signal ratio results were analyzed using a univariate analysis of variance. Additional signal-to-noise (SNR) measurements were performed in a phantom.Results3D VIBECAIPI-DIXON was preferred in 72.4% (both readers) and 2D FlashGRAPPA-fs in 3.4%/6.9% (reader 1/2) of cases with a kappa value of 0.756. The main reasons for this preference were homogenous fat saturation with 3D VIBECAIPI-DIXON and reduced motion artifacts due to a faster acquisition, leading to improved delineation of the pancreas. Signal ratios of pancreatic to fat signal for 3D VIBECAIPI-DIXON (10.08±3.48) and 2D FlashGRAPPA-fs (6.53±3.07) were statistically different (P< .001). However, no additional statistically significant differences in signal ratios were identified (range: 0.73±0.18 to 1.37±0.40; .514 < P< .961). SNR did not statistically significantly differ between the sequences.Conclusion3D VIBECAIPI-DIXON enables robust pancreatic imaging with a shorter time and improved fat suppression relative to conventional 2D FlashGRAPPA-fs. At an acquisition time of 12 seconds, 3D VIBECAIPI-DIXON can be obtained in considerably less time than standard fat-saturated VIBE sequences.