Gadda Davide, Mazzoni Lorenzo Nicola, Pasquini Luca, Busoni Simone, Simonelli Paolo, Giordano Gian Paolo
Neuroradiology, Careggi University Hospital, Largo Palagi 1, 50139, Florence, Italy.
Health Physics, Le Scotte University Hospital, Siena, Italy.
J Neuroimaging. 2017 Jan;27(1):128-134. doi: 10.1111/jon.12350. Epub 2016 Apr 15.
The role of apparent diffusion coefficient (ADC) for preoperative grading and treatment planning of high-grade gliomas (HGG) is still debated since the assumption of inverse correlation between ADC and cellularity is not completely coherent with the results of some studies. It has been recently hypothesized that restricted diffusivity in HGG may be related to hypoxic/ischemic changes inside the tumor. We therefore investigated the differences of ADC values between areas with magnetic resonance spectroscopy (MRS) markers of hypoxia and necrosis (lactate and lipid compounds) and regions with lack of both metabolites.
The MRS datasets and the corresponding ADC maps of 28 patients with HGG were retrospectively reviewed. Circular regions of interest (ROIs) were placed on ADC maps by means of spectral characteristics, considering the solid portions of gliomas. One-way ANOVA or Welch test were performed for multiple comparison of the Mean ADC, minimum ADC (minADC), and standard deviation of pixel-by-pixel ADC measurements (ADC SD) values among the groups of ROIs with lactate, lipids, and lack of both metabolites (LAC, LIP, and NEG group, respectively).
The minADC values in LAC group (908 ± 161 × 10 mm s ) were found to be significantly (P = .03) higher than in NEG group (792 ± 122 × 10 mm s ). We did not find other significant differences by the multiple comparison tests.
HGG areas with MRS markers of hypoxia and necrosis are not associated with restricted diffusivity. To explain the trend to diffusion facilitation in HGG lactate-expressing regions, we hypothesize a possible hypoxia-induced volume reduction of glioma cells with extracellular shift of cytoplasmic water.
表观扩散系数（ADC）在高级别胶质瘤（HGG）术前分级及治疗规划中的作用仍存在争议，因为ADC与细胞密度呈负相关这一假设与一些研究结果并不完全一致。最近有人提出，HGG中扩散受限可能与肿瘤内部的缺氧/缺血变化有关。因此，我们研究了具有缺氧和坏死磁共振波谱（MRS）标记物（乳酸和脂质化合物）的区域与缺乏这两种代谢物的区域之间ADC值的差异。
回顾性分析28例HGG患者的MRS数据集及相应的ADC图。根据光谱特征，在ADC图上放置圆形感兴趣区（ROI），考虑胶质瘤的实性部分。对具有乳酸、脂质以及缺乏这两种代谢物的ROI组（分别为LAC、LIP和NEG组）之间的平均ADC、最小ADC（minADC）以及逐像素ADC测量值的标准差（ADC SD）进行单因素方差分析或韦尔奇检验，以进行多重比较。
发现LAC组的minADC值（908±161×10⁻³mm²/s）显著高于NEG组（792±122×10⁻³mm²/s）（P = 0.03）。通过多重比较检验未发现其他显著差异。
具有缺氧和坏死MRS标记物的HGG区域与扩散受限无关。为了解释HGG乳酸表达区域扩散促进的趋势，我们假设可能存在缺氧诱导的胶质瘤细胞体积减小以及细胞质水向细胞外转移。
