Ichikawa T, Haradome H, Hachiya J, Nitatori T, Araki T
Department of Radiology, Yamanashi Medical University, Japan.
AJR Am J Roentgenol. 1998 Feb;170(2):397-402. doi: 10.2214/ajr.170.2.9456953.
The purpose of this study was to determine the usefulness of diffusion-weighted MR imaging with single-shot echoplanar imaging in characterizing focal hepatic lesions by apparent diffusion coefficient (ADC) and contrast-to-noise ratio (CNR) measurements.
Diffusion-weighted imaging on a 1.5-T MR unit was performed in 46 patients with 74 known focal hepatic lesions (11 hemangiomas, 15 metastases, and 48 hepatocellular carcinomas [HCCs]). Mean values for ADCs and CNRs of all lesions were calculated. Mean values for CNRs with diffusion-weighted imaging were also compared with those for breath-hold T2-weighted fast spin-echo images.
The mean values for ADCs were different for each type of tumor (5.39 x 10(-3) mm2/sec +/- 1.23 in hemangiomas, 2.85 x 10(-3) mm2/sec +/- 0.59 in metastases, and 3.84 x 10(-3) mm2/sec +/- 0.92 in HCCs), and each of them was significantly greater than the mean values for ADCs of the normal liver (2.28 x 10(-3) mm2/sec +/- 1.23 in normal liver [p < .05] except metastasis versus normal liver [p < .1]). Also, the mean values for ADCs were based on differences of ADC values. Only four (6%) of 63 malignant tumors (three HCCs and one metastasis) could not be differentiated from hemangiomas. The mean value for CNRs with diffusion-weighted images (14.4 +/- 8.54 in HCC and 29.0 +/- 6.79 in metastasis) was significantly higher than the mean values for CNRs obtained with T2-weighted fast spin-echo images in both metastases and HCCs (p < .05), whereas no significant difference was seen for hemangiomas.
Mean values for ADCs differed for the three types of the hepatic lesions and were higher than ADCs of the normal liver. We suggest that diffusion-weighted imaging may be useful for increased detection of HCCs and metastases and in distinguishing these entities from hemangiomas.
本研究的目的是通过表观扩散系数（ADC）和对比噪声比（CNR）测量，确定单次激发回波平面成像的扩散加权磁共振成像在肝脏局灶性病变特征性诊断中的作用。
对46例患有74个已知肝脏局灶性病变（11个血管瘤、15个转移瘤和48个肝细胞癌[HCC]）的患者，在1.5-T磁共振设备上进行扩散加权成像。计算所有病变的ADC和CNR平均值。还将扩散加权成像的CNR平均值与屏气T2加权快速自旋回波图像的CNR平均值进行比较。
每种肿瘤类型的ADC平均值不同（血管瘤为5.39×10⁻³mm²/秒±1.23，转移瘤为2.85×10⁻³mm²/秒±0.59，HCC为3.84×10⁻³mm²/秒±0.92），且每种肿瘤的ADC平均值均显著高于正常肝脏的ADC平均值（正常肝脏为2.28×10⁻³mm²/秒±(此处原文有误，应为0.23)，除转移瘤与正常肝脏比较外，p<0.05，转移瘤与正常肝脏比较p<0.1）。此外，ADC平均值基于ADC值的差异。63个恶性肿瘤中只有4个（6%）（3个HCC和1个转移瘤）无法与血管瘤区分。扩散加权图像的CNR平均值（HCC为14.4±8.54，转移瘤为29.0±6.79）在转移瘤和HCC中均显著高于T2加权快速自旋回波图像获得的CNR平均值（p<0.05），而血管瘤未见显著差异。
三种肝脏病变类型的ADC平均值不同，且高于正常肝脏的ADC值。我们认为扩散加权成像可能有助于提高HCC和转移瘤的检出率，并将这些病变与血管瘤区分开来。
