Abstract
BackgroundHepatocyte-specific gadolinium based contrast agents (HSCA) provide substantial information for the classification of liver lesions in magnetic resonance imaging (MRI). However, breathing artifacts which reduce image quality and diagnostic confidence of hepatobiliary phase acquisitions are regularly observed in clinical routine. The aim of this study was to evaluate two approaches to reduce breathing artifacts for hepatobiliary phase imaging.MethodsTwenty minutes after administration of a HSCA (gadoxetic acid), a T1-weighted VIBE sequence with radial k-space sampling (radialVIBE, 180 s acquisition time in free breathing) and a highly accelerated Cartesian VIBE with Dixon fat separation (CD-VIBE, CAIPIRINHA acceleration with r = 2 × 2, breath-hold 8–10 s) were acquired in 35 patients (12 female, 57 ± 13 years), who showed breath-holding difficulties in early phases of the examinations. Image quality (image sharpness, noise, artifacts, homogeneity of fat saturation, bile duct delineation and overall image quality) as well as conspicuity and liver-to-lesion signal intensity (SI) ratios of focal liver lesions were assessed for both radial- and CD-VIBE.ResultsOverall image quality was rated good to excellent for both sequences, while CD-VIBE was preferred in most cases. Though radialVIBE received better results regarding image noise and artifacts, both sequences were rated equally regarding bile duct delineation and sharpness. Focal liver lesion (n = 42) conspicuity was rated significantly better and SI-ratios were significantly higher on CD-VIBE (2.45 ± 1.44 vs. 1.61 ± 0.70 in radialVIBE, p = 0.0001). In three patients, CD-VIBE was rated non-diagnostic due to severe breathing artifacts, while radialVIBE was diagnostic in those patients.ConclusionBoth highly accelerated Cartesian as well as radial acquisition techniques provide good to excellent image quality in hepatobiliary phase MRI. In comparison, CD-VIBE offered better overall image quality and liver lesion conspicuity. However, radialVIBE was a valuable alternative in patients unable to sustain even short breath-hold intervals. Further studies including lager patient cohorts are desirable to allow a transfer of these results to a general patient population.
Highlights
Hepatocyte-specific gadolinium based contrast agents (HSCA) provide substantial information for the classification of liver lesions in magnetic resonance imaging (MRI)
Besides functional techniques like diffusion weighted imaging (DWI), hepatocyte-specific gadolinium based contrast agents (HSCA) can provide substantial information for the detection and classification of focal liver lesions, as HSCA allow the evaluation of hepatocyte metabolism [1]
Detection of small lesions is crucial to assess the disease burden in patients suffering from hepatocellular carcinoma (HCC) [2], when imaging is used for selection of liver transplant candidates
Summary
Hepatocyte-specific gadolinium based contrast agents (HSCA) provide substantial information for the classification of liver lesions in magnetic resonance imaging (MRI). Breathing artifacts which reduce image quality and diagnostic confidence of hepatobiliary phase acquisitions are regularly observed in clinical routine. Besides functional techniques like diffusion weighted imaging (DWI), hepatocyte-specific gadolinium based contrast agents (HSCA) can provide substantial information for the detection and classification of focal liver lesions, as HSCA allow the evaluation of hepatocyte metabolism [1]. Breathing artifacts which may impair image quality and decrease diagnostic confidence are regularly observed in clinical routine, with small lesions likely to be missed. Previous studies on dynamic arterial phase imaging found that patients receiving HSCA suffered from breath-holding difficulties, probably due to their typically reduced overall clinical condition [5]. Critically ill patients might get exhausted after such relatively long in-scanner times, worsening their already reduced breath-holding capabilities
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