体素位置对单体素磁共振波谱结果的影响。
Effect of voxel position on single-voxel MR spectroscopy findings.
作者信息
Ricci P E, Pitt A, Keller P J, Coons S W, Heiserman J E
机构信息
Department of Neuroradiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA.
出版信息
AJNR Am J Neuroradiol. 2000 Feb;21(2):367-74.
BACKGROUND AND PURPOSE
Single-voxel MR spectroscopy is a widely used tool for evaluating brain tumors. Although extensive data are available on the MR spectral appearance of tumors, less is known about the effect of voxel position on the accuracy of single-voxel MR spectroscopy findings. The purpose of this study was to test the hypothesis that the accuracy of single-voxel MR spectroscopy in the categorization of lesions as either tumor or not tumor is dependent on voxel position.
METHODS
Fifty single-voxel MR spectra acquired with a fully automated stimulated-echo spectroscopy sequence were reviewed retrospectively in 43 patients with new or previously treated intra-axial brain tumors. Spectra were analyzed for the presence of choline, creatine, N-acetylaspartate (NAA), and lipid/lactate. Choline/creatine and NAA/creatine peak area ratios were assessed qualitatively. Lesions were grouped into one of three categories on the basis of spectral pattern: tumor, not tumor, or indeterminate. Results of MR spectroscopy were compared with the final histopathologic diagnosis.
RESULTS
Histologic confirmation was obtained in 19 patients; MR spectra were interpretable in 17 of those. MR spectra correctly categorized nine of 17 lesions (six tumor, three nontumor). All eight misdiagnosed lesions were tumors. When the MR spectroscopy voxel included the enhancing edge of the lesion, the spectra correctly categorized seven of eight lesions (four of five tumors and all three cases of radiation necrosis). When the MR spectroscopy voxel was positioned centrally within the lesion, the spectra correctly reflected histologic outcome in two of nine lesions (all tumors).
CONCLUSION
The reliability of single-voxel MR spectroscopy findings is dependent on voxel position. Spectra obtained from voxels at the enhancing edge of a tumor more accurately reflect lesion histopathology than do spectra obtained from the lesion center, even if the centrally placed voxels contain solidly enhancing tissue.
背景与目的
单体素磁共振波谱是评估脑肿瘤广泛使用的工具。尽管关于肿瘤的磁共振波谱表现已有大量数据，但关于体素位置对单体素磁共振波谱结果准确性的影响却知之甚少。本研究的目的是检验以下假设：单体素磁共振波谱在将病变分类为肿瘤或非肿瘤时的准确性取决于体素位置。
方法
回顾性分析了43例新发或既往接受过治疗的脑内肿瘤患者，使用全自动刺激回波波谱序列采集的50个单体素磁共振波谱。分析波谱中胆碱、肌酸、N-乙酰天门冬氨酸（NAA）和脂质/乳酸的存在情况。定性评估胆碱/肌酸和NAA/肌酸峰面积比。根据波谱模式将病变分为三类之一：肿瘤、非肿瘤或不确定。将磁共振波谱结果与最终组织病理学诊断进行比较。
结果
19例患者获得了组织学证实；其中17例的磁共振波谱可解释。磁共振波谱正确分类了17个病变中的9个（6个肿瘤，3个非肿瘤）。所有8个误诊病变均为肿瘤。当磁共振波谱体素包括病变的强化边缘时，波谱正确分类了8个病变中的7个（5个肿瘤中的4个以及所有3例放射性坏死）。当磁共振波谱体素位于病变中心时，波谱在9个病变中的2个（均为肿瘤）中正确反映了组织学结果。
结论
单体素磁共振波谱结果的可靠性取决于体素位置。从肿瘤强化边缘的体素获得的波谱比从病变中心获得的波谱更准确地反映病变组织病理学，即使位于中心的体素包含明显强化的组织。
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