Hayashida Y, Hirai T, Morishita S, Kitajima M, Murakami R, Korogi Y, Makino K, Nakamura H, Ikushima I, Yamura M, Kochi M, Kuratsu J-i, Yamashita Y
Department of Diagnostic Radiology, Graduate School of Medical Sciences, School of Medicine, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
AJNR Am J Neuroradiol. 2006 Aug;27(7):1419-25.
On diffusion-weighted imaging (DWI), metastatic tumors of the brain may exhibit different signal intensities (SI) depending on their histology and cellularity. The purpose of our study was to verify the hypotheses (1) that SI on DWI predict the histology of metastases and (2) that apparent diffusion coefficient (ADC) values reflect tumor cellularity.
We assessed conventional MR images, DWI, and ADC maps of 26 metastatic brain lesions from 26 patients, 13 of whom underwent surgery after the MR examination. Two radiologists performed qualitative assessment by consensus of the SI on DWI in areas corresponding to their enhancing portions. We measured the contrast-to-noise ratio (CNR) on T2-weighted images and normalized ADC (nADC) values, and compared them with tumor cellularity.
The mean SI on DWI and the CNR on T2-weighted images were significantly lower in well differentiated than in poorly differentiated adenocarcinomas and lesions other than adenocarcinoma. The mean nADC value was significantly higher in well differentiated than poorly differentiated adenocarcinomas and lesions other than adenocarcinoma. All 3 small-cell carcinomas and 1 large-cell neuroendocrine carcinoma exhibited high SI on DWI. The nADC value showed a significant inverse correlation with tumor cellularity. There was no significant correlation between the CNR and tumor cellularity.
The SI on DWI may predict the histology of metastases; well differentiated adenocarcinomas tended to be hypointense, and small- and large-cell neuroendocrine carcinomas showed hyperintensity. Their ADC values reflect tumor cellularity.
在扩散加权成像（DWI）上，脑转移瘤根据其组织学类型和细胞密度可能表现出不同的信号强度（SI）。我们研究的目的是验证以下假设：（1）DWI上的SI可预测转移瘤的组织学类型；（2）表观扩散系数（ADC）值反映肿瘤细胞密度。
我们评估了26例患者的26个脑转移瘤的常规磁共振成像、DWI和ADC图，其中13例患者在磁共振检查后接受了手术。两名放射科医生通过对DWI上与增强部分相对应区域的SI进行一致的定性评估。我们测量了T2加权图像上的对比噪声比（CNR）和标准化ADC（nADC）值，并将它们与肿瘤细胞密度进行比较。
高分化腺癌的DWI平均SI和T2加权图像上的CNR显著低于低分化腺癌和非腺癌病变。高分化腺癌的平均nADC值显著高于低分化腺癌和非腺癌病变。所有3例小细胞癌和1例大细胞神经内分泌癌在DWI上均表现为高SI。nADC值与肿瘤细胞密度呈显著负相关。CNR与肿瘤细胞密度之间无显著相关性。
DWI上的SI可能预测转移瘤的组织学类型；高分化腺癌往往呈低信号，小细胞和大细胞神经内分泌癌呈高信号。它们的ADC值反映肿瘤细胞密度。
