Department of Diagnostic Radiology, Hiroshima University.
FUJIFILM Healthcare Corporation.
Magn Reson Med Sci. 2023 Apr 1;22(2):241-252. doi: 10.2463/mrms.mp.2022-0041. Epub 2022 Jun 1.
The wavelet denoising with geometry factor weighting (g-denoising) method can reduce the image noise by adapting to spatially varying noise levels induced by parallel imaging. The aim of this study was to investigate the clinical applicability of g-denoising on hepatobiliary-phase (HBP) images with gadoxetic acid.
We subjected 53 patients suspected of harboring hepatic neoplastic lesions to gadoxetic acid-enhanced HBP imaging with and without g-denoising (gHBP and gHBP). The matrix size was reduced for gHBP images to avoid prolonging the scanning time. Two radiologists calculated the SNR, the portal vein-, and paraspinal muscle contrast-to-noise ratio (CNR) relative to the hepatic parenchyma (liver-to-portal vein- and liver-to-muscle CNR). Two other radiologists independently graded the sharpness of the liver edge, the visibility of intrahepatic vessels, the image noise, the homogeneity of liver parenchyma, and the overall image quality using a 5-point scale. Differences between gHBP and gHBP images were determined with the two-sided Wilcoxon signed-rank test.
The liver-to-portal- and liver-to-muscle CNR and the SNR were significantly higher on gHBP- than gHBP images (P < 0.01), as was the qualitative score for the image noise, homogeneity of liver parenchyma, and overall image quality (P < 0.01). Although there were no significant differences in the scores for the sharpness of the liver edge or the score assigned for the visibility of intrahepatic vessels (P = 0.05, 0.43), with gHBP the score was lower in three patients for the sharpness of the liver edge and in six patients for the visibility of intrahepatic vessels.
At gadoxetic acid-enhanced HBP imaging, g-denoising yielded a better image quality than conventional HBP imaging although the anatomic details may be degraded.
基于几何因子加权的小波去噪（g-去噪）方法可以适应平行成像引起的空间变化的噪声水平，从而降低图像噪声。本研究旨在探讨钆塞酸增强肝胆期（HBP）图像 g-去噪的临床适用性。
我们对 53 例疑似肝占位性病变的患者进行了钆塞酸增强 HBP 成像，包括 g-去噪（gHBP 和 gHBP）和常规 HBP 成像。为避免延长扫描时间，对 gHBP 图像进行了矩阵缩小。两名放射科医生计算了 SNR、门静脉和脊柱旁肌肉相对于肝实质的对比噪声比（CNR）（肝门静脉和肝肌肉 CNR）。另外两名放射科医生使用 5 分制独立评估肝边缘锐度、肝内血管可视性、图像噪声、肝实质均匀性和整体图像质量。使用双侧 Wilcoxon 符号秩检验确定 gHBP 和 gHBP 图像之间的差异。
gHBP 图像的肝门静脉和肝肌肉 CNR 和 SNR 明显高于 gHBP 图像（P <0.01），图像噪声、肝实质均匀性和整体图像质量的定性评分也明显更高（P <0.01）。虽然肝边缘锐度和肝内血管可视性的评分无显著差异（P=0.05，0.43），但在 gHBP 图像中，有 3 例患者肝边缘锐度评分较低，6 例患者肝内血管可视性评分较低。
在钆塞酸增强 HBP 成像中，g-去噪可获得优于常规 HBP 成像的图像质量，尽管解剖细节可能会降低。
