Center for Clinical Spectroscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Neuro Oncol. 2018 Aug 2;20(9):1262-1271. doi: 10.1093/neuonc/noy022.
Isocitrate dehydrogenase (IDH) mutations result in abnormal accumulation of 2-hydroxyglutarate (2HG) in gliomas that can be detected by MRS. We examined the diagnostic accuracy of 2HG single-voxel spectroscopy (SVS) and chemical shift imaging (CSI) in both newly diagnosed and posttreatment settings.
Long echo time (97 ms) SVS and CSI were acquired in 85 subjects, including a discovery cohort of 39 patients who had postoperative residual or recurrent glioma with confirmed IDH-mutation status and 6 normal volunteers, a prospective preoperative validation cohort of 24 patients with newly diagnosed brain mass, and a prospective recurrent-lesion validation cohort of 16 previously treated IDH-mutant glioma patients with suspected tumor recurrence. The optimal thresholds for both methods in diagnosing IDH status were determined by receiver operating characteristic analysis in the discovery cohort and then applied to the 2 validation cohorts to assess the diagnostic performance.
The optimal 2HG/creatine thresholds of SVS and 75th percentile CSI for IDH mutations were 0.11 and 0.23, respectively. When applied to the validation sets, the sensitivity, specificity, and accuracy in distinguishing IDH-mutant gliomas in the preoperative cohort were 85.71%, 100.00%, and 94.12% for SVS, and 100.00%, 69.23%, and 81.82% for CSI, respectively. In the recurrent-lesion cohort, the sensitivity, specificity, and accuracy for discriminating IDH-positive recurrent gliomas were 40.00%, 62.50%, and 53.85% for SVS, and 66.67%, 100.00%, and 86.67% for CSI, respectively.
2HG MRS provides diagnostic utility for IDH-mutant gliomas both preoperatively and at time of suspected tumor recurrence. SVS has a better diagnostic performance for untreated IDH-mutant gliomas, whereas CSI demonstrates greater performance in identifying recurrent tumors.
异柠檬酸脱氢酶（IDH）突变导致 2-羟戊二酸（2HG）在胶质瘤中的异常积累，可通过 MRS 检测到。我们检查了 2HG 单体波谱（SVS）和化学位移成像（CSI）在新诊断和治疗后环境中的诊断准确性。
在 85 名受试者中采集长回波时间（97ms）SVS 和 CSI，包括一组 39 名术后残留或复发性 IDH 突变状态得到证实的胶质瘤患者的发现队列和 6 名正常志愿者，一组 24 名新诊断脑肿块的前瞻性术前验证队列，以及一组 16 名先前治疗过的 IDH 突变型胶质瘤患者的前瞻性复发性病变验证队列，这些患者疑似肿瘤复发。在发现队列中通过接收者操作特征分析确定两种方法诊断 IDH 状态的最佳阈值，然后将其应用于两个验证队列以评估诊断性能。
SVS 和 75%CSI 的最佳 2HG/肌酸阈值分别为 0.11 和 0.23。当应用于验证集时，术前队列中区分 IDH 突变型胶质瘤的 SVS 的灵敏度、特异性和准确性分别为 85.71%、100.00%和 94.12%，CSI 分别为 100.00%、69.23%和 81.82%。在复发性病变队列中，SVS 区分 IDH 阳性复发性胶质瘤的灵敏度、特异性和准确性分别为 40.00%、62.50%和 53.85%，CSI 分别为 66.67%、100.00%和 86.67%。
2HG MRS 为术前和疑似肿瘤复发时的 IDH 突变型胶质瘤提供了诊断效用。SVS 对未经治疗的 IDH 突变型胶质瘤具有更好的诊断性能，而 CSI 则在识别复发性肿瘤方面表现出更好的性能。
