1Translational and Molecular Imaging Institute; and.
Departments of2Neurosurgery.
J Neurosurg. 2020 Feb 28;134(3):771-779. doi: 10.3171/2019.12.JNS192940. Print 2021 Mar 1.
Endoscopic surgery is an effective treatment strategy for pituitary adenomas; however, intrinsic tumor properties such as tumor consistency can challenge or preclude gross-total resection. Preoperative characterization of tumor consistency may help to guide the surgical approach and to predict the extent of resection that is possible. Advanced radiological modalities such as 7T diffusion-weighted imaging (DWI) may be useful in probing biological tissue properties of pituitary adenomas. The objective of the present study was to examine 7T DWI as a novel method of measuring the consistency of pituitary adenomas.
Thirteen patients with pituitary macroadenomas underwent 7T MRI, including a DWI image acquisition. Tumor apparent diffusion coefficient (ADC) was normalized to the adjacent temporal gray matter ADC. All patients underwent resection, and a single neurosurgeon blinded to ADC values rated tumor firmness from 1 (least firm) to 5 (most firm) using objective criteria. The tumor specimens were evaluated histopathologically for cellularity, collagen content, and vascularity by a neuropathologist who was also blinded to ADC values. The tumor ADC was correlated with intraoperative consistency rating, histopathology, and extent of resection. Receiver operating characteristic (ROC) curve analyses were performed to identify thresholds to predict tumor consistency.
Corrected ADC values were significantly correlated with both tumor firmness (r = -0.60, p = 0.029) and the extent of trichrome staining (r = -0.72, p = 0.009) such that greater ADC values were associated with both decreased tumor firmness and decreased collagen staining. Correlations between ADC values and tumor vascularity were not significant (r = -0.09, p = 0.78). Corrected ADC values in totally resected tumors (1.54) were greater than those in subtotally resected tumors (0.85) (p = 0.02), and ADC values were greater with moderate tumor cellularity (1.51) than with high tumor cellularity (0.8) (p = 0.035). There was a trend-level association for partial resections to exhibit greater tumor firmness rating (3 vs 1.7; p = 0.051). Finally, the degree of trichrome staining positively correlated with tumor firmness (r = 0.60, p = 0.04). The optimal threshold for predicting intraoperative consistency rating was an ADC ratio of 0.87 (sensitivity 80%, specificity 100%, area under the curve [AUC] 0.90; p = 0.043). The optimal cutoff for distinguishing the extent of resection was 1.19 (sensitivity 85.7%, specificity 83.3% AUC 0.833; p = 0.046).
The authors' results suggest that a high-resolution ADC of pituitary adenomas is a sensitive measure of tumor consistency. 7T DWI may hold clinical value in the preoperative workup and surgical management of patients with pituitary macroadenomas.
内镜手术是治疗垂体腺瘤的有效策略；然而，肿瘤的固有特性，如肿瘤硬度，可能会对肿瘤的全切除造成挑战或阻碍。术前对肿瘤硬度的特征进行描述有助于指导手术方法，并预测可能的切除范围。如 7T 弥散加权成像（DWI）等先进的影像学方法可能有助于探测垂体腺瘤的生物学组织特性。本研究旨在探讨 7T DWI 作为一种测量垂体腺瘤硬度的新方法。
13 例垂体大腺瘤患者接受了 7T MRI 检查，包括 DWI 图像采集。肿瘤表观弥散系数（ADC）与相邻颞叶灰质 ADC 进行标准化。所有患者均接受了手术切除，一名对 ADC 值不知情的神经外科医生根据客观标准对肿瘤硬度进行评分，范围为 1（最软）至 5（最硬）。肿瘤标本由一名对 ADC 值不知情的神经病理学家进行细胞密度、胶原含量和血管密度的组织病理学评估。使用受试者工作特征（ROC）曲线分析确定预测肿瘤硬度的阈值。
校正后的 ADC 值与肿瘤硬度（r = -0.60，p = 0.029）和三色染色程度（r = -0.72，p = 0.009）显著相关，即较大的 ADC 值与肿瘤硬度降低和胶原染色减少相关。ADC 值与肿瘤血管化之间的相关性不显著（r = -0.09，p = 0.78）。完全切除肿瘤的 ADC 值（1.54）大于部分切除肿瘤（0.85）（p = 0.02），中等细胞密度肿瘤的 ADC 值（1.51）大于高细胞密度肿瘤（0.8）（p = 0.035）。部分切除肿瘤硬度评分较高（3 分 vs 1.7 分；p = 0.051）有趋势关联。最后，三色染色程度与肿瘤硬度呈正相关（r = 0.60，p = 0.04）。预测术中一致性评分的最佳 ADC 比值为 0.87（敏感性 80%，特异性 100%，曲线下面积[AUC]为 0.90；p = 0.043）。区分切除程度的最佳截断值为 1.19（敏感性 85.7%，特异性 83.3%，AUC 为 0.833；p = 0.046）。
作者的研究结果表明，垂体腺瘤的高分辨率 ADC 是肿瘤硬度的敏感测量指标。7T DWI 在垂体大腺瘤患者的术前评估和手术管理中具有临床价值。
