Optimal flip angle of Gd-EOB-DTPA-enhanced MRI in patients with hepatocellular carcinoma and liver metastasis

To investigate optimal flip angle (FA) of three-dimensional fat-suppressed T1-weighted image on Gd-EOB-DTPA-enhanced MRI. Forty-five patients with 35 hepatocellular carcinomas (HCCs) and 16 liver metastases (METs) were investigated. Signal-to-noise ratio (SNR), tumor-to-liver contrast (TLC) of HCC and MET, visual image quality (IQ) and lesion conspicuity (LeCo) were evaluated at hepatobiliary phase with different FAs (FA15A degrees-30A degrees-45A degrees-60A degrees in 13 patients, FA5A degrees-10A degrees-15A degrees-20A degrees-25A degrees in 32 patients). TLC gradually showed better in range from FA15A degrees to FA60A degrees and FA5A degrees to FA25A degrees, but SNRs gradually decreased. SNR and TLC-MET at FA15A degrees were significantly better than those at FA45A degrees and FA60A degrees. SNR at FA10A degrees was significantly higher than at FA5A degrees, FA20A degrees, and FA25A degrees. TLC-HCC and TLC-MET at FA5A degrees were inferior to other FAs. IQs and LeCos at FA15A degrees and FA30A degrees were superior to those at FA45A degrees and FA60A degrees. IQs at FA5A degrees and FA25A degrees were significantly lower than those at FA10A degrees-20A degrees, although LeCos for HCC and MET at FA25A degrees were superior to those at FA5A degrees-20A degrees. FA ranging from 10A degrees to 20A degrees is suitable for hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI, to image HCC and MET.