原发性颅内恶性淋巴瘤的MRI诊断

目的探讨原发性颅内恶性淋巴瘤的MRI表现特征。方法回顾性分析13例经病理证实的原发性脑内恶性淋巴瘤的临床和影像学资料（13例均有MRI平扫和增强资料，其中2例有CT平扫和增强资料，3例仅有CT平扫资料），并与病理资料进行对照分析。结果13例中9例为单发，4例多发，共有19个病灶。原发性颅内恶性淋巴瘤的影像学形态多为类圆形肿块或结节，瘤周水肿及占位效应较轻。5例CT平扫表现为等或略高于脑组织密度影，无出血和钙化：13例MR平扫中，T1WI上11个病灶呈等信号，8个病灶呈稍低信号；在T2WI上，12个病灶呈等信号，7个呈稍低信号。增强扫描显示12个病灶呈团块状或结节状均匀性明显强化，7个呈不均匀明显强化，中心囊变坏死区无强化。病理上肿瘤细胞均呈弥漫密集分布，胞质及水分少，核大，网状纤维染色显示纤维结构较丰富。结论原发性脑内恶性淋巴瘤的病理学基础决定其CT、MRI表现特征，结合其影像学表现和临床资料多可做出正确诊断。

MRI diagnosis of primary malignant lymphoma in the brain

Objective To investigate MRI features of primary malignant lymphoma in the brain. Methods Clinical materials and MRI findings in 13 patients with histologically proved primary malignant lymphomas in the brain were retrospectively reviewed. All the patients were performed both preconstrast and postconstrast MRI scanning, while precontrast and postcontrast CT scanning in 2 cases and only precontrast CT scanning in 3 cases. The findings were compared with pathological results. Results Of the total 19 lesions in 13 cases, single lesion was seen in 9 and multiple lesions in 4. Usually, the lesion was presented as an oval mass or nodule with slight para - tumorous edema and space - occupying effect. On plain CT scans of 5 cases, the lesion presented as iso - or slight hyper - density without hemorrhage or calcification. Of 19 lesions found on plain MRI in 13 cases, 11 presented as iso- signal and 8 as slight hypo- singal on T1WI,while 12 displayed as iso -signal and 7 as slightly hypo -signal on T2WI. In 12 lesions obvious homogeneous mass - like of nodular enhancement and 7 lesions non - homogeneous were seen on Gd - DPTA enhanced MRI. Pathologically ,the tumor cells were diffusely distributed and roughly same - sized with less cytoplasm and enlarged nucleus. The tumor was rich in fibers. Conclusion Primary malignant lymphoma in the brain carries certain MRI features, which are in according with its corresponding pathologic characteristics. Correct diagnosis can be made in most cases when imaging findings are combined with clinical information.