Helton K J, Phillips N S, Khan R B, Boop F A, Sanford R A, Zou P, Li C S, Langston J W, Ogg R J
Department of Radiological Sciences, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
AJNR Am J Neuroradiol. 2006 Apr;27(4):786-93.
Conventional MR imaging permits subcategorization of brain stem tumors by location and focality; however, assessment of white matter tract involvement by tumor is limited. Diffusion tensor imaging (DTI) is a promising method for visualizing white matter tract tumor involvement supratentorially. We investigated the ability of DTI to visualize and quantify white matter tract involvement in pontine tumors.
DTI data (echo-planar, 1.5T) were retrospectively analyzed in 7 patients with pontine tumors (6 diffuse, 1 focal), 4 patient controls, and 5 normal volunteers. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from the diffusion tensor in 6 regions of interest: bilateral corticospinal tracts, transverse pontine fibers, and medial lemnisci. Relationships between FA and ADC values and results of the neurologic examinations were evaluated.
The corticospinal tracts and transverse pontine fibers were affected more often than the medial lemnisci. The DTI parameters (FA and ADC) were significantly altered in all tracts of patients with pontine tumors (P < .05), compared with those values in the control groups. A marginally significant (P = .057) association was seen between the severity of cranial nerve deficit and decreased FA.
DTI provided superior visualization and quantification of tumor involvement in motor, sensory, and transverse pontine tracts, compared with information provided by conventional MR imaging. Thus, DTI may be a sensitive measure of tract invasion. Further prospective studies are warranted to assess the ability of DTI to delineate tumor focality and improve risk stratification in children with pontine tumors.
传统磁共振成像（MR）可根据脑干肿瘤的位置和灶性进行亚分类；然而，对肿瘤侵犯白质束的评估有限。扩散张量成像（DTI）是一种在幕上可视化白质束肿瘤侵犯情况的有前景的方法。我们研究了DTI可视化和量化脑桥肿瘤中白质束侵犯的能力。
对7例脑桥肿瘤患者（6例弥漫性，1例局灶性）、4例患者对照和5名正常志愿者的DTI数据（回波平面成像，1.5T）进行回顾性分析。从6个感兴趣区域的扩散张量计算分数各向异性（FA）和表观扩散系数（ADC）：双侧皮质脊髓束、脑桥横纤维和内侧丘系。评估FA和ADC值与神经学检查结果之间的关系。
皮质脊髓束和脑桥横纤维比内侧丘系更常受影响。与对照组相比，脑桥肿瘤患者所有束的DTI参数（FA和ADC）均有显著改变（P <.05）。在脑神经功能缺损的严重程度与FA降低之间存在边缘显著相关性（P = 0.057）。
与传统MR成像提供的信息相比，DTI在运动、感觉和脑桥横束中对肿瘤侵犯的可视化和量化效果更佳。因此，DTI可能是一种检测束侵犯的敏感方法。有必要进行进一步的前瞻性研究，以评估DTI在描绘肿瘤灶性和改善脑桥肿瘤患儿风险分层方面的能力。
