Validation of 10-Minute Delayed Hepatocyte Phase Imaging with 30° Flip Angle in Gadoxetic Acid-Enhanced MRI for the Detection of Liver Metastasis.

Abstract

OBJECTIVES: To compare 10-minute delayed hepatocyte phase imaging using a 30° flip angle (10 min-FA30) and 20-minute hepatocyte phase imaging using a 10° FA (20 min-FA10) in gadoxetic acid-enhanced MRI of patients with possible liver metastases, regarding lesion-to-liver contrast-to-noise ratio (CNR) and focal hepatic lesion (FHL) detection to evaluate whether 10 min-FA30 would be superior to 20 min-FA10. MATERIALS AND METHODS: Eighty-three patients with 248 liver metastases and 78 benign FHLs who underwent gadoxetic acid-enhanced MRI with 10 min-FA30 and 20 min-FA10 were enrolled. Lesion-to-liver CNRs were compared between the two image groups. Two radiologists independently assessed the presence of FHLs using a four-point scale and detection sensitivity was calculated. RESULTS: The mean CNR for liver metastases on the 10 min-FA30 (248.5 ± 101.6) were significantly higher than that of the 20 min-FA10 (187.4 ± 77.4) (p < 0.001). The mean CNR difference between the two image groups was 61.2 ± 56.8. There was no significant difference in detection sensitivity of FHLs for two readers between 10 min-FA30 (mean 97.7%) and 20 min-FA10 (mean 97.9%), irrespective of the lesion size or malignancy. CONCLUSION: 10 min-FA30 yielded higher CNR with similar sensitivity compared to 20 min-FA10. This finding indicates that 10 min-FA30 can potentially replace 20 min-FA10 with higher diagnostic performance and save 10 minutes of time.