少突胶质细胞肿瘤临床和MR表现

目的 探讨少突胶质细胞肿瘤的MR表现特点及鉴别诊断.方法 回顾性分析34例经手术病理证实的少突胶质细胞肿瘤的临床和MR资料,包括肿瘤位置、信号、大小、强化表现和磁共振波谱(MRS)表现特点.结果 Ⅱ级少突胶质细胞瘤22例,Ⅲ级间变性少突胶质细胞瘤12例.肿瘤位于额叶22例,颞叶4例,同时累及额叶和颞叶7例,视交叉1例.25例肿瘤位置表浅.间变性少突胶质细胞瘤中囊变坏死11例,出血和钙化各3例.少突胶质细胞瘤中囊变坏死6例,出血2例,钙化8例.少突胶质细胞瘤肿瘤直径平均35 mm,间变性少突胶质细胞瘤肿瘤直径平均58 mm.11例间变性少突胶质细胞瘤呈显著不规则或环形强化, 6例少突胶质细胞瘤轻度强化,6例无强化,4例呈环形不规则轻到中度强化.6例间变性少突胶质细胞瘤行MRS检查,5例胆碱化合物/磷酸肌酸(Cho/Cr)>4,12例少突胶质细胞瘤行MRS检查,10例Cho/Cr在2.3~3.3之间,2例Cho/Cr<2.结论 位于额叶,靠近脑表面、累及皮层是少突胶质细胞肿瘤最主要的MR表现特点,显著不规则或环形强化、MRS检查Cho/Cr>4提示肿瘤为间变性.     

胼胝体肿瘤的影像学诊断

目的 探讨发生于胼胝体的不同类型肿瘤的影像学表现.方法 回顾性分析25例发生于胼胝体的不同类型的肿瘤.分析各种肿瘤在不同影像学检查方法下的表现特点.结果 低级别星形细胞瘤1例,间变性星形细胞瘤2例,胶质母细胞瘤7例,少突胶质细胞瘤1例,间变性少突星形细胞瘤1例,少突一星形细胞瘤1例,原发恶性淋巴瘤10例,转移瘤1例,脂肪瘤1例.肿瘤最大直径7 cm,最小0.5 cm.肿瘤实性部分T1WI为等或低信号,T2WI为等或稍高信号,部分肿瘤伴囊变坏死.脂肪瘤CT平扫为低密度,CT值-85 HU.增强扫描星形细胞瘤呈不均匀、环状或蝶翼状强化,恶性淋巴瘤呈明显实性或环状强化,胶质母细胞瘤和淋巴瘤多向脑室或邻近脑质浸润.结论 胼胝体肿瘤的影像学表现具有特征性,可为手术切除肿瘤提供指导作用.     

胼胝体肿瘤的影像学诊断

目的 探讨发生于胼胝体的不同类型肿瘤的影像学表现.方法 回顾性分析25例发生于胼胝体的不同类型的肿瘤.分析各种肿瘤在不同影像学检查方法下的表现特点.结果 低级别星形细胞瘤1例,间变性星形细胞瘤2例,胶质母细胞瘤7例,少突胶质细胞瘤1例,间变性少突星形细胞瘤1例,少突一星形细胞瘤1例,原发恶性淋巴瘤10例,转移瘤1例,脂肪瘤1例.肿瘤最大直径7 cm,最小0.5 cm.肿瘤实性部分T1WI为等或低信号,T2WI为等或稍高信号,部分肿瘤伴囊变坏死.脂肪瘤CT平扫为低密度,CT值-85 HU.增强扫描星形细胞瘤呈不均匀、环状或蝶翼状强化,恶性淋巴瘤呈明显实性或环状强化,胶质母细胞瘤和淋巴瘤多向脑室或邻近脑质浸润.结论 胼胝体肿瘤的影像学表现具有特征性,可为手术切除肿瘤提供指导作用.     

大脑皮层及皮层下肿瘤的MRI表现

目的研究大脑皮层及皮层下肿瘤的MRI表现。方法回顾性分析187例大脑皮层及皮层下肿瘤患者的术前常规MR图像,总结常见大脑皮层及皮层下病变的MRl表现及鉴别要点。结果 187例大脑皮层及皮层下肿瘤中少突星形细胞瘤80例,弥漫性星形细胞瘤22例,胚胎发育不良性神经上皮瘤(DNET)17例,胶质母细胞瘤14例,节细胞胶质瘤11例,少突胶质细胞瘤11例,间变性少突星形细胞瘤6例,间变性少突胶质细胞瘤4例,多形性黄色星形细胞瘤(PXA)4例,恶性淋巴瘤4例,室管膜瘤4例,间变性室管膜瘤3例,胶质肉瘤2例,幕上原始神经外胚层肿瘤(PNET)2例,神经节细胞瘤1例,转移瘤1例,间变性星形细胞瘤1例。结论大脑皮层及皮层下肿瘤MRI特征性表现有助于诊断与鉴别诊断。     

不典型少突胶质细胞瘤1例

少突胶质细胞瘤属神经上皮组织肿瘤,肿瘤内钙化常见且明显,但巨大囊变且CT显示瘤内无明显钙化的少突胶质瘤十分罕见,未见大宗报道.本院近期收治1例经病理证实的巨大囊变少突胶质瘤患者,现报道如下.     

替莫唑胺联合光动力显微手术综合治疗功能区脑胶质瘤长期随访研究

正目的:研究化疗联合光动力综合治疗脑胶质瘤以来共45例功能区高级别胶质瘤患者的临床症状改善情况,生存率和影像学变化。方法:功能区恶性脑胶质瘤病例25例,皆有影像学及病理证实,男性13例,女性12例;间变星形细胞瘤6例,间变室管膜瘤3例、间变少枝胶质细胞瘤1例、多形胶质母细胞瘤15例。随机选取同期非光动力治疗的高级别功能区胶质     

间变性少突胶质细胞瘤的影像学表现

目的探讨颅内间变性少突胶质细胞瘤的多种影像学特点,提高对该病的认识。方法回顾性分析经病理证实的10例间变性少突胶质细胞瘤的多种影像学表现。结果 10例病灶均位于幕上,9例单发,1例多发,其中4例位于额叶,3例位于顶叶,额颞叶、丘脑及颞叶各1例。3例实性,其中1例明显强化,2例中度强化;4例囊实性,其中1例实性部分明显强化,2例中度强化,1例轻度强化,囊性部分未见强化;3例囊性,均呈明显环形强化。6例行MRS检查,MRS示病灶Cho/NAA比值明显升高,但囊性肿瘤Cho/NAA比值低于实性或囊实性肿瘤。3例患者行CT检查,病灶表现为低密度,均出现条索状钙化灶。结论尽管间变性少突胶质细胞瘤影像学表现多样,但仍具有一定特征性,结合多种影像学技术可以提高诊断,为临床选择治疗方法提供指导作用。     

神经元和混合性神经元-神经胶质肿瘤的MRI表现

目的：提高对神经元和混合性神经元-神经胶质肿瘤的影像特征的认识。方法：回顾性分析11例经手术病理证实的神经元和混合性神经元-神经胶质肿瘤病例的影像学资料及临床资料。结果：3例中枢神经细胞瘤均发生于侧脑室内,瘤体呈囊实性,1例伴不规则钙化,增强扫描示肿瘤实质明显强化。2例脑室外神经细胞瘤,1例位于基底节区,瘤体呈实性伴部分钙化,增强后呈不均匀强化;1例发生于颈髓,肿瘤内有液化坏死,增强后轻度强化。3例节细胞胶质瘤,病变均呈囊实性混杂信号,瘤体实质部分明显不均匀强化。3例节细胞瘤,病变均为实性,信号均匀或混杂,增强扫描示肿瘤呈轻度～明显强化。结论：神经元和混合性神经元-神经胶质肿瘤的影像学表现有一定的特征性,结合临床病史综合分析能提高术前诊断准确性。     

胶质瘤恶性转化预判研究进展

<正>脑胶质瘤是成人颅脑最常见的原发恶性肿瘤,WHO Ⅱ～Ⅲ级胶质瘤占胶质瘤约45%^[1],WHO Ⅱ级胶质瘤被称为低级别胶质瘤（low-grade gliomas, LGG）,组织学中存在非典型细胞核,导致肿瘤不可避免地以不同的速度发展^[2],其恶性转化率约为35%～89%^[3]。间变性弥漫性胶质瘤（星形细胞瘤、少突胶质细胞瘤和少突星形细胞瘤）等WHO Ⅲ级肿瘤,初次治疗后复发率高达38%^[4],     

儿童胶质神经元和神经元肿瘤的影像学表现

目的:探讨儿童中枢神经系统胶质神经元和神经元肿瘤的影像学征象,旨在提高对此类疾病的诊断水平。方法:回顾性分析经病理确诊的44例儿童中枢神经系统胶质神经元和神经元肿瘤的临床表现及影像学资料。结果:44例中,18例为胚胎发育不良性神经上皮瘤,病变全部位于幕上,主要累及皮层,根据MRI表现分为Ⅰ型(类囊性)9例,Ⅱ型(结节状)3例,Ⅲ型(发育异常样)6例;17例为节细胞胶质瘤,病变全部位于幕上,好发于颞叶,多呈囊实性,3例可见钙化;5例婴儿促纤维增生型节细胞胶质瘤/星形细胞瘤,病变全部位于幕上,以囊实性为主,实性成分可见强化,1例可见钙化;2例中枢神经细胞瘤,病变位于幕上脑室内,1例可见多发囊变,增强扫描肿瘤内实性成分明显强化;1例弥漫性软脑膜胶质神经元肿瘤,病变位于小脑、脑干及脊髓,幕下软脑膜多发囊变,增强扫描软脑膜弥漫性增厚、强化;1例小脑发育不良性节细胞瘤,位于左侧小脑半球及小脑蚓部,可见钙化,增强扫描呈轻度强化,可见典型“虎纹征”。结论:儿童胶质神经元和神经元肿瘤影像学具有其特征性,结合临床病史有利于提高术前诊断准确性。     

Intracranial oligodendrogliomas: imaging findings in 35 untreated cases

The radiographic findings in 35 cases of untreated intracranial oligodendrogliomas were reviewed. The mean age of the patients was 34.6 years, and seizure disorder and headache were the most frequent presenting symptoms. Slightly less than two-thirds of the tumors were histologically pure and almost half were low-grade. Most lesions were cerebral and peripheral in location, and the majority were in the frontal lobes. On CT the tumors were usually hypo- or isodense. Contrast enhancement of tumor occurred in nearly half the cases, and was usually mild and poorly defined. Tumor calcification often occurred, and hemorrhage or cystic formation was not infrequent. Occasionally, calvarial erosion was associated with the tumors because of their peripheral location and slow-growing nature. The lesions were usually sharply demarcated and without edema. MR most frequently revealed hypointense lesions on T1-weighted images and abnormal hyperintensity on T2-weighted scans. In regard to grading or purity of oligodendrogliomas, no significant correlations were found except for a suggestion that higher-grade and mixed tumors tend to enhance more often on CT. The radiographic features of oligodendroglioma are quite characteristic but not pathognomic. A high preoperative suspicion might lead to more appropriate tumor management. MR, although less sensitive in detecting tumor calcification, is superior to CT in defining the tumor extent, which is beneficial for surgical and postsurgical radiotherapy planning.     

Differentiation of low-grade oligodendrogliomas from low-grade astrocytomas by using quantitative blood-volume measurements derived from dynamic susceptibility contrast-enhanced MR imaging

BACKGROUND AND PURPOSE: Histopathologic evaluation remains the reference standard for diagnosis of glioma and classification of histologic subtypes, but is challenged by subjective criteria, tissue sampling error, and lack of specific tumor markers. Anatomic imaging is essential for surgical planning of gliomas but is limited by its nonspecificity and its inability to depict beyond morphologic aberrations. The purpose of our study was to investigate dynamic susceptibility contrast-enhanced (DSC) MR imaging characteristics of the two most common subtypes of low-grade infiltrating glioma: astrocytoma and oligodendroglioma. We hypothesized that tumor blood-volume measurements, derived from DSC MR imaging, would help differentiate the two on the basis of differences in tumor vascularity. METHODS: We studied 25 consecutive patients with treatment-naive, histopathologically confirmed World Health Organization grade II astrocytoma (n = 11) or oligodendroglioma (n = 14). All patients underwent anatomic and DSC MR imaging immediately before surgical resection. Histologic confirmation was obtained in all patients. Anatomic MR images were analyzed for morphologic features, and DSC MR data were processed to yield quantitative cerebral blood volume (CBV) measurements. RESULTS: The maximum relative CBV (rCBV(max)) in tumor ranged from 0.48 to 1.34 (0.92 +/- 0.27, median +/- SD) in astrocytomas and from 1.29 to 9.24 (3.68 +/- 2.39) in oligodendrogliomas. The difference in median rCBV(max) between the two tumor types was significant (P < .0001). CONCLUSION: The tumor rCBV(max) measurements derived from DSC MR imaging were significantly higher in low-grade oligodendrogliomas than in astrocytomas. Our findings suggest that tumor rCBV(max) derived from DSC MR imaging can be used to distinguish between the two low-grade gliomas.     

Imaging diagnosis and fundamental knowledge of common brain tumors in adults

The most common primary brain tumors in Japanese adults are meningiomas, gliomas, pituitary adenomas, and schwannomas, which together account for 84.0% of all primary brain tumors. The typical imaging findings of these tumors are well known by radiologists; therefore, the clinical and pathological issues, including terminology, genetics, and relation to hormones are discussed in this article. Other diseases important for the differential diagnoses are also mentioned. The molecular genetic analysis of brain tumors has recently become important. For instance, genetic analysis is important for differentiating oligodendroglial tumors from astrocytic tumors, and the gene mutation predicts response to chemotherapy for anaplastic oligodendrogliomas. Background factors such as hormones, history of cranial irradiation, and medications influence oncogenesis, tumor growth, and tumor appearances as seen by imaging modalities. A differential diagnosis with knowledge of the above may have some advantages over diagnoses based on imaging findings alone. Nonneoplastic diseases such as abscesses and demyelinating diseases may mimic gliomas. Pituitary adenomas may be confused with nonneoplastic conditions such as physiological hypertrophy and Rathke's cleft cyst. Such misdiagnoses would result in a treatment protocol very different from what would be suitable. Such conditions should be carefully distinguished from neoplasms. This work was presented as an educational lecture at the 64^th Japan Radiological Society meeting (April 2005) in Yokohama.     

Low-grade and anaplastic gliomas: differences in architecture evaluated with diffusion-tensor MR imaging

PURPOSE: To prospectively evaluate whether diffusion-tensor magnetic resonance (MR) imaging depicts differences in World Health Organization (WHO) grade II and III glial brain tumors on the basis of tumor architecture and peritumoral tract invasion. MATERIALS AND METHODS: The study protocol was approved by the local ethics committee, and written informed consent was obtained. Diffusion-tensor MR imaging was performed in 23 patients (15 men, eight women; mean age, 47 years) with histologically confirmed brain gliomas. Eleven of the 23 tumors were low-grade gliomas (WHO grade II) and 12 were anaplastic gliomas (WHO grade III). Regions of interest were placed in the tumor center, tumor border, normal-appearing white matter (NAWM) adjacent to the tumor, and NAWM of the contralateral hemisphere. fractional anisotropy (FA) ratios were calculated for regions of interest in relation to the NAWM of the contralateral hemisphere. Pairwise comparisons were performed by using the Mann-Whitney U test. RESULTS: Median FA ratios for grade II versus grade III gliomas were 0.406 versus 0.405, respectively, for tumor center, 0.733 versus 0.449, respectively, for tumor border, and 0.962 versus 0.943, respectively, for NAWM adjacent to the tumor. Differences in FA ratio between low-grade and high-grade tumors were significant in the tumor border only (P = .01). Differences in FA ratio were not significant between low-grade and high-grade gliomas in the tumor center or in the NAWM adjacent to the tumor. CONCLUSION: The periphery of low-grade gliomas contains a considerable amount of preserved fiber tracts. In high-grade gliomas, however, most of these tracts are disarranged. Low FA ratios in the tumor center are consistent with a high degree of disorganization of myelinated fiber tracts in the center of both low-grade and high-grade gliomas.     

Pathological factors contributing to crossed cerebellar diaschisis in cerebral gliomas: a study combining perfusion,diffusion, and structural MR imaging

Purpose

To investigate imaging features of crossed cerebellar diaschisis (CCD) in cerebral gliomas, and its underlying pathophysiological mechanisms.

Methods

Thirty-three pre-surgical patients with cerebral gliomas and 33 healthy controls underwent arterial spin-labeling, diffusion tensor imaging, and high-resolution T1-weighted imaging using MRI, in order to estimate cerebral blood flow (CBF), white matter integrity, and lesion volume, respectively. Asymmetry indices of CBF in the cerebellum were used for evaluating the level of CCD in the patients. These indices were correlated with clinical variables (lesion size and position, tumor histological grade, and CBF asymmetry) and diffusion tensor imaging parameters (fractional anisotropy and number of fibers in the cortico-ponto-cerebellar pathway and across the cerebral hemispheres), respectively.

Results

The patients showed decreased CBF in the cerebellar hemisphere contralateral to the supratentorial tumor, and increased CBF asymmetry in the cerebellum (both P?<?0.05). CCD levels in high-grade gliomas were higher than those of low-grade gliomas (P?<?0.05). CCD levels were negatively correlated with the size of the supratentorial lesions, and positively correlated with FA asymmetry in the cerebral fibers (both P?<?0.05).

Conclusions

CCD in cerebral gliomas was specifically associated with tumor histological grade, lesion size, and white matter impairments in the hemisphere ipsilateral to the tumor. The findings implicated that observing CCD might have potential for assisting grading diagnosis of cerebral gliomas.

     

Perfusion MR Imaging in Gliomas: Comparison with Histologic Tumor Grade

Objective

To determine the usefulness of perfusion MR imaging in assessing the histologic grade of cerebral gliomas.

Materials and Methods

In order to determine relative cerebral blood volume (rCBV), 22 patients with pathologically proven gliomas (9 glioblastomas, 9 anaplastic gliomas and 4 low-grade gliomas) underwent dynamic contrast-enhanced T2*-weighted and conventional T1- and T2-weighted imaging. rCBV maps were obtained by fitting a gamma-variate function to the contrast material concentration versus time curve. rCBV ratios between tumor and normal white matter (maximum rCBV of tumor / rCBV of contralateral white matter) were calculated and compared between glioblastomas, anaplastic gliomas and low-grade gliomas.

Results

Mean rCBV ratios were 4.90°±1.01 for glioblastomas, 3.97°±0.56 for anaplastic gliomas and 1.75°±1.51 for low-grade gliomas, and were thus significantly different; p < .05 between glioblastomas and anaplastic gliomas, p < .05 between anaplastic gliomas and low-grade gliomas, p < .01 between glioblastomas and low-grade gliomas. The rCBV ratio cutoff value which permitted discrimination between high-grade (glioblastomas and anaplastic gliomas) and low-grade gliomas was 2.60, and the sensitivity and specificity of this value were 100% and 75%, respectively.

Conclusion

Perfusion MR imaging is a useful and reliable technique for estimating the histologic grade of gliomas.     

增强磁敏感成像在颅内常见肿瘤中的应用研究

目的 探讨增强磁敏感成像(contrast-enhanced susceptibility-weighted imaging,CE-SWI)在颅内常见肿瘤中的应用价值.资料与方法 14例颅内常见肿瘤中,脑膜瘤6例,高级别胶质瘤4例,脑转移瘤3例,髓母细胞瘤1例),分析其CE-SWI特点.结果 CE-SWI示所有肿瘤边界清楚,瘤内分布静脉血管.4例高级别胶质瘤、3例脑膜瘤(矢状窦旁2例,直窦旁1例)及3例转移瘤显示瘤周水肿,与液体衰减反转恢复序列(FLAIR)一致.3例高级别胶质瘤瘤内见出血灶.4例高级别胶质瘤、2例脑膜瘤、3例转移瘤及1例髓母细胞瘤明显强化,与常规增强T_1WI一致.4例脑膜瘤明显环形强化,常规增强T_1WI均匀明显强化.6例脑膜瘤与1例脑膜转移瘤均显示"脑膜尾征".结论 CE-SWI具有磁敏感效应、对比增强以及FLAIR等多重效应,有助于颅内常见肿瘤的术前诊断,减少扫描序列.     

Low-grade gliomas: dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging--prediction of patient clinical response

PURPOSE: To determine retrospectively whether relative cerebral blood volume (CBV) measurements can be used to predict clinical response in patients with low-grade gliomas. MATERIALS AND METHODS: Approval for this retrospective HIPAA-compliant study was obtained from the Institutional Board of Research Associates, with waiver of informed consent. Thirty-five patients (23 male and 12 female patients; median age, 39 years; range, 4-80 years) with histologically diagnosed low-grade gliomas (21 low-grade astrocytomas and 14 low-grade oligodendrogliomas and low-grade mixed oligoastrocytomas) were examined with dynamic susceptibility-weighted contrast material-enhanced perfusion magnetic resonance (MR) imaging. Wilcoxon tests were used to compare patients in different response categories (complete response, stable, progressive, death) with respect to baseline relative CBV. Kaplan-Meier survival curves, log-rank tests, and Weibull survival models were used to characterize and evaluate the association of baseline relative CBV with time to progression. Tumor volumes and relative CBV measurements were obtained at initial examination and follow-up. RESULTS: Lesions with relative CBV less than 1.75 had a median time to progression of 4620 days +/- 433 (standard deviation), and lesions with relative CBV more than 1.75 had a median time to progression of 245 days +/- 62. Patients who had an adverse event (either death or progression) had significantly higher (P = .003) relative CBV than did patients without adverse events (either complete response or stable disease). Lesions with low baseline relative CBV had stable tumor volumes at follow-up over time, whereas those with high baseline relative CBV (>1.75) had progressively increasing tumor volumes over time. CONCLUSION: Dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging can help to identify low-grade gliomas that will progress rapidly and a subset of low-grade gliomas that have a propensity for malignant transformation.     

Brain gliomas: sonographic characterization

To determine the ability of ultrasound (US) to help characterize brain lesions and determine the best site for biopsy, intraoperative sonographic examination of nine intracerebral gliomas was performed and correlated with the preoperative computed tomographic (CT), gross intraoperative, and histopathologic findings. Real-time US provided a precise and rapid method for intraoperative localization of intracerebral neoplasms in all cases. While the sonographic appearance of gliomas is nonspecific, US added information on tumor characterization to that provided by CT. All gliomas were sonographically echogenic compared with surrounding brain. US permitted good characterization of the cystic components of tumors; portions of the operation therefore involved surgical drainage rather than resection. Autopsy specimens from five anaplastic cerebral gliomas were examined with US and found to be echogenic. The central portions of all five tumors were echogenic and corresponded to areas of tumor necrosis; thus they were poor sites for biopsy. Alternatively, the best site for biopsy was the inner portion of the echogenic margin of the mass, which usually represented areas of active tumor growth. The information obtained from both preoperative CT and intraoperative US is beneficial in characterizing lesions and predicting the best site for biopsy.