XD-GRASPを用いた肝臓の高分解能自由呼吸肝胆相MRI

High-resolution free-breathing hepatobiliary phase MRI of the liver using XD-GRASP.

抄録

目的:

XD-GRASP（eXtra-Dimension Golden-angle RAdial Sparse Parallel）MRI法を用いた肝臓の高分解能自由呼吸（FB）肝胆道位相画像の性能を評価する。

PURPOSE: To evaluate the performance of high-resolution free-breathing (FB) hepatobiliary phase imaging of the liver using the eXtra-Dimension Golden-angle RAdial Sparse Parallel (XD-GRASP) MRI technique.

方法:

肝病変を有し、肝特異的造影剤を用いた動的造影MRIを施行した臨床患者58名（男性41名、平均年齢52.9±12.9歳）を本研究のために前向きに募集した。息止め体積補間検査（BH-VIBE）撮像とFB撮像の両方が肝胆道相中に行われた。FB画像はstack-of-stars golden-angle radialシーケンスを用いて取得し、XD-GRASP法を用いて再構成した。各画像の全体的な画質、肝エッジの鮮明さ、肝血管の明瞭さ、病変の目立ちやすさ、および全体的なアーチファクトのレベルを、撮影方式を盲検化した2人の経験豊富な放射線科医が独立して採点した。統計解析にはノンパラメトリックの両側Wilcoxon符号順位検定を用いた。

METHODS: Fifty-eight clinical patients (41 males, mean age = 52.9 ± 12.9) with liver lesions who underwent dynamic contrast-enhanced MRI with a liver-specific contrast agent were prospectively recruited for this study. Both breath-hold volumetric interpolated examination (BH-VIBE) imaging and FB imaging were performed during the hepatobiliary phase. FB images were acquired using a stack-of-stars golden-angle radial sequence and were reconstructed using the XD-GRASP method. Two experienced radiologists blinded to acquisition schemes independently scored the overall image quality, liver edge sharpness, hepatic vessel clarity, conspicuity of lesion, and overall artifact level of each image. The non-parametric paired two-tailed Wilcoxon signed-rank test was used for statistical analysis.

結果:

BH-VIBE画像と比較して、XD-GRASP画像は肝エッジの鮮鋭度（4.83±0.45 vs 4.29±0.46）で有意に高いスコア（P<0.05）を得た。29±0.46）、肝血管の明瞭度（4.64±0.67 vs 4.15±0.56）、病変の明瞭度（4.75±0.53 vs 4.31±0.50）で有意に高いスコアを示した。全体的な画質（4.61±0.50 vs 4.74±0.47）および全体的なアーチファクトのレベル（4.13±0.44 vs 4.05±0.61）については、BH-VIBE画像とXD-GRASP画像の間に有意差はなかった（P>0.05）。

RESULTS: Compared to BH-VIBE images, XD-GRASP images received significantly higher scores (P < 0.05) for the liver edge sharpness (4.83 ± 0.45 vs 4.29 ± 0.46), the hepatic vessel clarity (4.64 ± 0.67 vs 4.15 ± 0.56) and the conspicuity of lesion (4.75 ± 0.53 vs 4.31 ± 0.50). There were no significant differences (P > 0.05) between BH-VIBE and XD-GRASP images for the overall image quality (4.61 ± 0.50 vs 4.74 ± 0.47) and the overall artifact level (4.13 ± 0.44 vs 4.05 ± 0.61).

結論:

従来のBH-VIBE MRIと比較して、FB Radial撮影とXD-GRASP再構成を組み合わせることで、肝胆道相における肝臓の高空間分解能撮影が容易になる。この向上により、肝臓の可視化と評価が大幅に改善される。

CONCLUSION: Compared to conventional BH-VIBE MRI, FB radial acquisition combined with XD-GRASP reconstruction facilitates higher spatial resolution imaging of the liver during the hepatobiliary phase. This enhancement can significantly improve the visualization and evaluation of the liver.