High resolution navigated three‐dimensional T₁‐weighted hepatobiliary MRI using gadoxetic acid optimized for 1.5 tesla

Abstract

Purpose To determine optimal delay times and flip angles for T1-weighted hepatobiliary imaging at 1.5T with gadoxetic acid and to demonstrate the feasibility of using a high-resolution navigated optimized T1-weighted pulse sequence to evaluate biliary disease. Materials and Methods Eight healthy volunteers were scanned at 1.5T using a T1-weighted 3D-SPGR pulse sequence following the administration of 0.05 mmol/kg of gadoxetic acid. Navigator-gating enabled acquisition of high spatial resolution (1.2 × 1.4 × 1.8 mm3, interpolated to 0.7 × 0.7 × 0.9 mm3) images in approximately 5 minutes of free breathing. Multiple breath-held acquisitions were performed at flip angles between 15° and 45° to optimize T1 weighting. To evaluate the performance of this optimized sequence in the setting of biliary disease, the image quality and biliary excretion of 51 consecutive clinical scans performed to assess primary sclerosing cholangitis (PSC) were evaluated. Results Optimal hepatobiliary imaging occurs at 15–25 minutes, using a 40° flip angle. The image quality and visualization of biliary excretion in the PSC scans were excellent, despite the decreased liver function in some patients. Visualization of reduced excretion often provided diagnostic information that was unavailable by conventional magnetic resonance cholangiopancreatography (MRCP). Conclusion High-resolution navigated 3D-SPGR hepatobiliary imaging using gadoxetic acid and optimized scan parameters is technically feasible and can be clinically useful, even in patients with decreased hepatobiliary function.

Intraindividual Crossover Comparison of Gadoxetic Acid Dose for Liver MRI in Normal Volunteers

“…We used muscle as a surrogate for weakly enhancing liver lesions such as hypovascular metastasis. 7,18 We used the following equations to calculate the SNR of the liver, portal vein, and muscle:…”

“…[3][4][5][6] Typically, maximum liver-to-lesion contrast is obtained in the hepatobiliary phase, approximately 20 min after injection, and good liver-to-lesion contrast persists about 2 to 3 hours. 7 In the hepatobiliary phase, normal liver and bile appear hyperintense from the presence of gadolinium, whereas blood vessels and focal liver lesions appear hypointense. This contrast enables detection of even very small hepatic metastases or hepatocellular carcinoma as hypointense lesions in bright liver tissue.…”

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

“…Classically, the hepatocyte phase has been deˆned as beginning approximately 20 min after contrast injection and lasting at least 2 hours. 12,33 In one Phase II study of gadoxetic acid, the tumorto-liver contrast plateaued 20 min after contrast injection, remained steady an additional 25 min. 23 However, it is common to see hepatocyte phase images obtained only 10 to 20 min after contrast injection.…”

“…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. 33 Coronal or sagittal images of good quality can be reconstructed from the isovoxel axial images with submillimeter spatial resolution. 33,34 How to shorten examination time A 20-min waiting period for the hepatocyte phase is su‹cient to obtain other sequences, so many researchers have attempted to shorten examination time by obtaining T 2 -weighted and diŠu-sion-weighted images after gadoxetic acid administration.…”

“…33 Coronal or sagittal images of good quality can be reconstructed from the isovoxel axial images with submillimeter spatial resolution. 33,34 How to shorten examination time A 20-min waiting period for the hepatocyte phase is su‹cient to obtain other sequences, so many researchers have attempted to shorten examination time by obtaining T 2 -weighted and diŠu-sion-weighted images after gadoxetic acid administration. Acquisition of T 2 -weighted images after gadoxetic acid injection has been demonstrated without compromise of image contrast.…”