Liver MRI in the hepatocyte phase with gadolinium‐EOB‐DTPA: Does increasing the flip angle improve conspicuity and detection rate of hypointense lesions?

Abstract

Purpose: To compare conspicuity and detection rate of hypointense lesions on T1-weighted (T1w) gradient echo (GRE) sequences with low and high flip angles (FA) in hepatocyte phase magnetic resonance imaging (MRI) using gadoxetate disodium. Materials and Methods:This Health Insurance Portability and Accountability Act (HIPAA)-compliant study was Institutional Review Board (IRB)-approved. The study population consisted of patients with hypointense liver lesions undergoing MRI with gadoxetate disodium, with hepatocyte-phase fat suppressed 3D T1w GRE sequences at both low (10)(11)(12) ) and high (30-35 ) FA. Contrast-tonoise ratios (CNRs) were calculated for liver parenchyma vs. large lesions and common bile duct (CBD) vs. liver. Three radiologists each assigned a conspicuity score (CS) for each lesion detected at low or high FA. Paired Student's t-tests compared the lesion detection (LD) rate using only the hepatocyte phase data set compared with the entire MRI examination, and CS for low and high FA.Results: In all, 57 large and 70 small lesions were identified in 18 patients. Average LD and CS were significantly greater at high FA versus low FA overall (LD 89.0% vs. 79.5%; CS 2.8 vs. 2.2; P < 0.05) and for small lesions (81.4% vs. 65.7%; 2.5 vs. 1.8; P < 0.05). Average liver-tolesion CNR for large lesions and CBD-to-liver CNR was significantly greater at high FA (P < 0.05). Conclusion:Increasing the FA in hepatocyte phase MRI with gadoxetate disodium improves hypointense lesion detection and conspicuity, particularly for small lesions.

Rules, Roles, and Room for Discussion in Gadoxetic Acid-enhanced Magnetic Resonance Liver Imaging: Current Knowledge and Future Challenges

“…Yet, a larger ‰ip angle may be optimal to maximize tumor-toliver contrast because the presence of contrast agent can shorten T 1 relaxation time in the liver during the hepatocyte phase; recent reports suggests a 309angle. 30,31 A greater ‰ip angle can be especially helpful when imaging patients with chronic liver disease, whose impaired hepatic function and/or gadoxetic acid uptake may make it di‹cult to obtain su‹cient tumor-to-liver contrast. 32 Respiratory-triggered high resolution 3D-GRE sequence using navigator echo has been proposed to obtain hepatocyte phase images with improved spatial Magnetic Resonance in Medical Sciences resolution, especially for the z axis.…”

Navigated three-dimensional T1-weighted gradient-echo sequence for gadoxetic acid liver magnetic resonance imaging in patients with limited breath-holding capacity

“…Considering that hepatic vessel clarity can be the result of spatial resolution and contrast resolution, and that we used the same FA (12°) for these two sequences, the same FA may have attributed to the similar contrast between the liver and hepatic vessels on HBP images. We believe that the use of a higher FA [37,38] which was suggested in a previous study [13] on navigated T1WI may further improve the contrast resolution. Finally, long acquisition time of navigated LAVA impedes its application to dynamic sequences, especially AP imaging on gadoxetic acid MRI, which is a weakness of navigated LAVA compared to recently developed techniques such as compressed sensing or non-Cartesian reconstruction methods.…”

The Impact of Flip Angle and TR on the Enhancement Ratio of Dynamic Gadobutrol-enhanced MR Imaging: <i>In Vivo</i> VX2 Tumor Model and Computer Simulation

“…In general, the choice of a larger FA will help increase ER in 2D SPGR, even in 3D SPGR. 26,27 Angiogenesis generally produces greater blood flow in tumor than normal tissue. Use of a larger FA increases the effect of inflow, and the inflow effect could help to differentiate tumor from normal tissue.…”