Sundgren Pia C, Fan Xiaoying, Weybright Patrick, Welsh Robert C, Carlos Ruth C, Petrou Myria, McKeever Paul E, Chenevert Thomas L
Department of Radiology, University of Michigan Health Systems, Ann Arbor, MI 48109-0030, USA.
Magn Reson Imaging. 2006 Nov;24(9):1131-42. doi: 10.1016/j.mri.2006.07.008. Epub 2006 Sep 18.
The purpose of this study was to assess the use of diffusion tensor imaging (DTI) in the evaluation of new contrast-enhancing lesions and perilesional edema in patients previously treated for brain neoplasm in the differentiation of recurrent neoplasm from treatment-related injury.
Twenty-eight patients with new contrast-enhancing lesions and perilesional edema at the site of previously treated brain neoplasms were retrospectively reviewed. Nine directional echoplanar DTIs with b=1000 s/mm(2) were obtained using a single-shot spin-echo echoplanar imaging. Standardized regions of interest were manually drawn in several regions. Mean apparent diffusion coefficient (ADC), fractional anisotropy (FA) and eigenvalue indices (lambda( parallel) and lambda( perpendicular)) and their ratios relative to the contralateral side were compared in patients with recurrent neoplasm versus patients with radiation injury, as established by histological examination or by clinical course, including long-term imaging studies and magnetic resonance spectroscopy.
The ADC values in the contrast-enhancing lesions were significantly higher (P=.01) for the recurrence group (range=1.01 x 10(-3) to 1.66 x 10(-3) mm(2)/s; mean+/-S.D.=1.27+/-0.15) than for the nonrecurrence group (range=0.9 x 10(-3) to 1.31 x 10(-3) mm(2)/s; mean+/-S.D.=1.12+/-0.14). The ADC ratios in the white matter tracts in perilesional edema trended higher (P=.09) in treatment-related injury than in recurrent neoplasm (mean+/-S.D.=1.85+/-0.30 vs. 1.60+/-0.27, respectively). FA ratios were significantly higher in normal-appearing white matter (NAWM) tracts adjacent to the edema in the nonrecurrence group (mean+/-S.D.=0.89+/-0.15) than in those in the recurrence group (mean+/-S.D.=0.74+/-0.14; P=.03). Both eigenvalue indices lambda( parallel) and lambda( perpendicular) were significantly higher in contrast-enhancing lesions in the recurrence group than in those in the nonrecurrence group (P=.02). As well, both eigenvalue indices lambda( parallel) and lambda( perpendicular) were significantly higher in perilesional edema than in normal white matter (P<.01 and P<.001, respectively) in both groups.
The assessment of diffusion properties, especially ADC values and ADC ratios, in contrast-enhancing lesions, perilesional edema and NAWM adjacent to the edema in the follow-up of new contrast-enhancing lesions at the site of previously treated brain neoplasms may add to the information obtained by other imaging techniques in the differentiation of radiation injury from tumor recurrence.
本研究旨在评估弥散张量成像（DTI）在评估既往接受过脑肿瘤治疗的患者新出现的强化病灶及病灶周围水肿方面，对鉴别肿瘤复发与治疗相关损伤的作用。
回顾性分析28例既往脑肿瘤治疗部位出现新强化病灶及病灶周围水肿的患者。采用单次激发自旋回波平面成像，获取9个方向、b值为1000 s/mm²的平面回波DTI图像。在多个区域手动绘制标准化感兴趣区。比较复发患者与经组织学检查或临床病程（包括长期影像学研究和磁共振波谱）证实为放射性损伤患者的平均表观扩散系数（ADC）、各向异性分数（FA）、特征值指数（λ∥和λ⊥）及其与对侧的比值。
复发组强化病灶的ADC值（范围为1.01×10⁻³至1.66×10⁻³ mm²/s；均值±标准差=1.27±0.15）显著高于非复发组（范围为0.9×10⁻³至1.31×10⁻³ mm²/s；均值±标准差=1.12±0.14；P = 0.01）。治疗相关损伤患者病灶周围水肿白质束的ADC比值高于肿瘤复发患者，差异有统计学意义（P = 0.09）（均值±标准差分别为1.85±0.30和1.60±0.27）。非复发组水肿相邻正常白质（NAWM）束的FA比值（均值±标准差=0.89±至1.66×10⁻³ mm²/s；均值±标准差=1.27±0.15）显著高于复发组（均值±标准差=0.74±0.14；P = 0.03）。复发组强化病灶的特征值指数λ∥和λ⊥均显著高于非复发组（P = 0.02）。此外，两组病灶周围水肿的特征值指数λ∥和λ⊥均显著高于正常白质（分别为P < 0.01和P < 0.001）。
在既往脑肿瘤治疗部位新出现强化病灶的随访中，评估强化病灶、病灶周围水肿及水肿相邻NAWM的弥散特性，尤其是ADC值和ADC比值，可能为其他成像技术鉴别放射性损伤与肿瘤复发提供更多信息。
