Effect of the Relationship between Respiratory Interval and Temporal Resolution on Image Quality in Free-breathing Abdominal MR Imaging.

PURPOSE

To evaluate how the relationship between respiratory interval (RI) and temporal resolution (TR) impacts image quality in free-breathing abdominal MRI (FB-aMRI) using golden-angle radial sparse parallel (GRASP).

METHODS

Ten healthy volunteers (25.9 ± 2.5 years, four women) underwent 2 mins free-breathing fat-suppression T1-weighted imaging using GRASP at RIs of 3 and 5s (RI and RI, respectively) and retrospectively reconstructed at TR of 1.8, 2.9, 4.8, and 7.7s (TR, TR, TR, and TR, respectively) in each patient. The standard deviation (SD) under the diaphragm was measured using SD maps showing the discrepancy for each horizontal section at all TRs. Two radiologists evaluated image quality (visualization of the right hepatic vein at the confluence of the inferior vena cava, posterior segment branch of portal vein, pancreas, left kidney, and artifacts) at all TRs using a 5-point scale.

RESULTS

The SD was significantly higher at TR compared to TR (P < 0.01) and TR (P < 0.001), as well as at TR compared to TR (P < 0.01) for both RIs. The SD between TR and TR did not differ for both RIs. For all visual assessment metrics, the TR scores were significantly lower than the TR and TR scores for both RIs. The pancreas and left kidney scores at TR were significantly lower than those at TR (P < 0.05) for RI. Additionally, the left kidney score at TR was lower than that at TR (P < 0.05) for RI. All scores at TR, TR, and TR were similar for RI, while those at TR and TR were similar for RI.

CONCLUSION

Prolonging the TRs compared to RIs enhances image quality in FB-aMRI using GRASP.