Early MRI findings in High Grade Glioma

Magnetic resonance imaging (MRI) is more sensitive than computerized tomography in the detection of many intracerebral lesions; however, the significance of some MRI findings may be unclear. Over four years, nine patients, aged 40–79 years, have been encountered whose initial MRI scans were negative or had minimal abnormalities and soon thereafter had high grade glioma. Initial MRI was performed in eight patients for new-onset seizures and one patient for a focal deficit. MRI was negative in four of the patients and mildly abnormal in five of the patients (small areas of increased T2 and/or minimal enhancement). The initial diagnoses usually included inconclusive differentials of stroke and infection with neoplasm less frequently considered. Radiographic progression leading to the diagnosis of high grade glioma became evident on repeat MRI in 1–8 months with six patients showing progression within three months. All patients underwent surgery and had histologic diagnosis of glioma. Although MRI is quite sensitive, four of the initial scans were negative with reasonable quality studies. Conversely, in five of the initial scans, the tumors were detected when so small that the radiographic findings were not typically diagnostic. Glioma must be considered as a possible cause of initial seizures or new neurologic deficits in adults with normal or minimally abnormal MRI. In this group, seizures were the overwhelming hallmark of presentation. In such a clinical situation, close follow-up with short interval repeat MRI should be performed.     

肝脏原发性平滑肌瘤影像学表现

Objective: To investigate the imaging features of primary hepatic leiomyoma. Methods: 3 patients of primary hepatic leiomyoma confirmed by pathology without immunodeficiency were retrospectively analyzed about CT and MRI findings, clinical and pathological correlation. 2 cases had routine CT scan, 2 cases had routine MRI. Results: 2 case CT scans showed low-density lesions, 2 cases MRI showed lesions with long T1 and long T2 signal. One case of uniform density and signal showed homogeneous enhancement; two cases showed uneven density and signal, of which one case was inhomogeneous enhancement. 3 cases presented pseudocapsule without hepatic cirrhosis and venous tumor thrombus. Pathology showed spindle tumor cell proliferation and capillary hyperplasia; one case showed central hyalinization and one case central liquefaction necrosis. Conclusion: Primary hepatic leiomyoma is a hypervascular tumor, and CT and MRI help in the diagnosis.     

Early diagnosis of spinal-epidural metastasis by magnetic resonance imaging

Sixteen patients with various types of cancer who developed pain along the axial spine were prospectively studied by magnetic resonance imaging (MRI). The studies were performed with a Fonar Beta-3000 (Fonar Co., Melville, NY) permanent magnet operating at 0.3 Tesla (T). Detailed neurologic examinations were followed by bone x-rays, bone scans, and MRI. In 12 patients there were focal neurologic findings. Bone x-rays and bone scans were diagnostic for metastatic disease in 10 cases; MRIs were consistent with metastatic spinal-epidural disease in all 16 patients. Magnetic resonance imaging revealed bone involvement in three patients whose x-rays and bone scans were both negative indicating a higher degree of sensitivity. In six patients thecal compression was obvious on MRI; in three of these previous myelograms had been interpreted as negative. These early results suggest that MRI can serve as a useful tool for diagnosing early spinal-epidural metastases.     

Radiopathological characteristics of cerebellar malignant glioma in adults

Our aim was to extract the radiopathological features of cerebellar malignant glioma in adults from the four cases we encountered. All four cases (two men and two women, aged 52–80 years; mean age, 67 years) had a floating sensation or vertigo at the onset of their disease. Initially, these patients were given a diagnosis of cerebellar infarction or cavernous angioma, or had faint abnormalities in the cerebellum that were overlooked. These patients were followed up for 2–14 months (mean, 6 months), and the tumor was detected when their clinical symptoms deteriorated. The tumor was located in the hemisphere in one patient and in the vermis in three patients. MRI revealed ring-like enhancement in two patients and nodular enhancement in two patients. All patients underwent subtotal tumor resection, followed by postoperative radiochemotherapy. However, three patients died at 16 to 44 months (mean, 28 months), and cerebrospinal fluid (CSF) dissemination was observed in three patients. Two cases were classified as WHO grade III and two as WHO grade IV. The pathological features were typical of malignant glioma, partially presenting the features of low-grade glioma, such as pilocytic, astrocytic, or oligodendroglial components. Nuclear pleomorphism and vascular endothelial proliferation were prominent, and micronecrosis was relatively less evident. The MIB-1 index was 12%–40%, and most of the patients were p53 protein positive. At the onset of cerebellar malignant glioma, diagnostic imaging shows few signs of brain tumor. Thereafter, tumors grow in a short period of time, following a rapid clinical course. Because cerebellar malignant glioma is a rare disease, it is difficult to differentiate it from metastatic brain tumors and primary central nervous system lymphoma by preoperative imaging. Some patho logical features suggesting malignant transformation from low-grade glioma were detected.     

Cushing's disease: Pituitary imaging

Fourteen patients with adrenocorticotropic hormone (ACTH)-dependent hypercortisolism underwent pituitary scanning with computed axial tomography (CT) and magnetic resonance imaging (MRI). Computed tomography revealed pituitary macroadenomas in two patients, pituitary hyperplasia in one and a suspicion of pituitary microadenoma in one. Thirteen patients underwent MRI. One with a macroadenoma diagnosed on CT did not undergo MRI. The MRI revealed a pituitary macroadenoma in one, microadenoma in three and hyperplasia in two cases. Magnetic resonance imaging following gadolinium diethylene triamine penta acetic acid (gd-DTPA) enhancement revealed four more pituitary microadenomas. All patients who had pituitary adenomas (micro and macro) and hyperplasia underwent trans-sphenoidal pituitary surgery. One of the two patients, who had an enlarged pituitary on imaging but no demonstrable adenoma, was found to have a microadenoma at surgery. Patients with ACTH-dependent hypercortisolism should undergo MRI of the pituitary gland to identify/localize corticotroph pituitary adenomas. The study should include gd-DTPA enhancement in cases where the scan is normal.     

Surveillance imaging in children with malignant CNS tumors: low yield of spine MRI

Magnetic resonance imaging (MRI) is routinely obtained in patients with central nervous system (CNS) tumors, but few studies have been conducted to evaluate this practice. We assessed the benefits of surveillance MRI and more specifically spine MRI in a contemporary cohort. We evaluated MRI results of children diagnosed with CNS tumors from January 2000 to December 2011. Children with at least one surveillance MRI following the diagnosis of medulloblastoma (MB), atypical teratoid rhabdoid tumor (ATRT), pineoblastoma (PB), supratentorial primitive neuroectodermal tumor, supratentorial high-grade glioma (World Health Organization grade III–IV), CNS germ cell tumors or ependymoma were included. A total of 2,707 brain and 1,280 spine MRI scans were obtained in 258 patients. 97 % of all relapses occurred in the brain and 3 % were isolated to the spine. Relapse was identified in 226 (8 %) brain and 48 (4 %) spine MRI scans. The overall rate of detecting isolated spinal relapse was 9/1,000 and 7/1,000 for MB patients. MRI performed for PB showed the highest rate for detecting isolated spinal recurrence with 49/1,000. No initial isolated spinal relapse was identified in patients with glioma, supratentorial primitive neuroectodermal tumor and ATRT. Isolated spinal recurrences are infrequent in children with malignant CNS tumors and the yield of spine MRI is very low. Tailoring surveillance spine MRI to patients with higher spinal relapse risk such as PB, MB with metastatic disease and within 3 years of diagnosis could improve allocation of resources without compromising patient care.     

心脏血管瘤的临床病理分析（附10例报告）

目的 探讨心脏血管瘤的临床病理特征,为临床诊疗及判断预后提供依据。方法 回顾性分析本院2003年2月至2014年2月经手术治疗的10例心脏血管瘤（海绵状血管瘤5例,毛细血管瘤4例,静脉性血管瘤1例）的临床资料及组织病理学特征。结果 多数肿瘤体积小,有蒂或无蒂,表面光滑,切面可呈蜂窝状,可见充满血栓的囊腔。主要成分为良性增生的血管内皮细胞,间质可见炎性细胞浸润。术后随访6个月至3年,3例失访,其余7例患者均恢复情况良好,无复发。结论 心脏血管瘤非常罕见,好发于心包的脏层,在儿童多发生在三尖瓣,无性别差异,可发生于任何年龄。术前确诊心脏血管瘤很困难,故手术切除标本应送病理检查确诊。本病预后良好,手术切除后极少复发,术后应定期随访。     

Contribution of single-photon emission computed tomography in the diagnosis and follow-up of CNS toxicity of a cytarabine-containing regimen in pediatric leukemia.

PURPOSE: Cytarabine (ara-C) is one of the most effective chemotherapeutic agents in patients with acute leukemia (AL), with a clear dose effect. Use of high-dose ara-C is hampered, however, by a noticeable toxicity, particularly to the CNS. We investigated the usefulness of CNS perfusion imaging with technetium-99m ((99m)Tc)-hexamethyl-propylene-amine oxime (HMPAO) single-photon emission computed tomography (SPECT) concurrent to magnetic resonance imaging (MRI) to specifically assess the effects of standard- and high-dose ara-C in children with AL. PATIENTS AND METHODS: Twenty-six perfusion studies using (99m)Tc-HMPAO SPECT were performed in 12 children (age range, 4 to 15 years) with AL after induction therapy, which consisted of a standard-dose ara-C, immediately after consolidation with high-dose ara-C, and later during follow-up (range, 6 to 44 months). The chemotherapy-related adverse events were monitored and correlated to SPECT and MRI. RESULTS: After the induction phase, all children were neurologically normal on MRI. On SPECT imaging, four children displayed a slightly heterogeneous perfusion. After high-dose ara-C (4 to 36 g/m(2)), five children had regressive neurologic signs of potential toxic origin. Of these five children, only one had an abnormal MRI scan, whereas all patients showed evidence of diffuse cerebral and/or cerebellar heterogeneous perfusion on SPECT. The seven other patients without any neurologic symptoms had normal MRI scans; SPECT was normal for three patients and abnormal for four patients. On follow-up, for four children who had presented with clinical neurologic toxicity, SPECT improved in three patients and remained unchanged in one patients. In two of these four children, delayed abnormalities (T2 white matter hypersignal and cerebellar atrophy) appeared on MRI scans. CONCLUSION: In our series, diffuse heterogeneous brain hypoperfusion is often the sole early objective imaging feature identified by SPECT of high-dose ara-C neurotoxicity, where MRI still demonstrates normal pictures.     

乳腺动态增强MRI及其后处理技术在乳腺肿瘤诊断中的应用

背景与目的：乳腺癌常用诊断手段主要包括体格检查、钼靶、超声等,MRI技术被视为乳腺疾病诊断最具有潜力的一种检查手段。本研究旨在探讨乳腺动态增强MRI及其后处理技术的优越性在临床诊断中的应用。方法：选取2006年5月至2007年9月在中山大学肿瘤防治中心行MRI检查的乳腺疾病初诊病例30例,全部行MRI平扫和动态增强扫描,并通过工作站分别进行减影处理、动态曲线绘制、三维立体重建等后处理。选取病灶远隔部位正常组织为对照．计算最大线性斜率比值。结果：本组30例患者共49个病灶,MRI诊断正确率93.3％。结论：乳腺MRI是一种敏感性和准确性较高的检查方式,动态增强扫描、减影处理、时间-信号曲线的处理、三维立体重建后处理以及最大线性斜率比值．均有助于乳腺病灶的正确诊断。     

Whole‐body magnetic resonance imaging in the detection of skeletal metastases in patients with prostate cancer

Whole‐body MRI is an effective method for evaluating the entire skeletal system in patients with metastatic disease. This study aimed to compare whole‐body MRI and radionuclide bone scintigraph in the detection of skeletal metastases in patients with prostate cancer. Patients with prostate cancer at high risk of skeletal metastasis with (i) prostate‐specific antigen of ≥50 ng/mL; (ii) composite Gleason score of ≥8 with prostate‐specific antigen of >20 ng/mL; or (iii) node‐positive disease were enrolled in this prospective study before systemic treatment was initiated. Whole‐body MR images and bone scans of 39 patients were analysed. Seven patients had bone metastases on bone scans, while seven patients had skeletal metastases by whole‐body MRI, with concordant findings only in four patients. Compared with the ‘gold standard’, derived from clinical and radiological follow‐up, the sensitivity for both bone scans and MRI was 70%, and the specificity for both was 100%. Magnetic resonance imaging detected 26 individual lesions compared with 18 lesions on bone scans. Only eight lesions were positive on both. Bone scans detected more rib metastases, while MRI identified more metastatic lesions in the spine. Whole‐body MRI and radionuclide bone scintigraphy have similar specificity and sensitivity and may be used as complementary investigations to detect skeletal metastases from prostate cancer.     

Glucose metabolism in brain tumours can be estimated using [18F]2-fluorodeoxyglucose positron emission tomography and a population-derived input function scaled using a single arterialised venous blood sample

The aim of this study was to assess simplified methods for deriving input functions for estimating glucose metabolism using 18F-FDG-PET. Nine glioma patients underwent paired 18F-FDG-PET scans as part of a phase II study and the data used to estimate the metabolic rate of glucose (MRGlu) using a population-derived input function (arterial data from 14 scans) scaled using a single arterial blood sample taken at 20 min. Paired studies were performed in four further glioma patients with stable disease at least four months following radiotherapy to determine whether scaling the population-derived input function using a 20-min arterialised venous or venous sample further simplified the method. The heated hand method was used to obtain arterialised venous blood that approximated arterial blood. In the 9 phase II glioma patients, there was a good, statistically significant correlation between the MRGlu values estimated using the individual arterial input functions and the single arterial sample scaled population-derived input functions (r(2)=0.88, p<0.001, n=36). Blood samples collected during three scans on two of the stable disease patients showed no significant difference between the arterialised venous and arterial plasma concentrations of 18F (p>0.1, n=15) when the degree of arterialisation of the blood was monitored and maintained using a thermocouple. A significant difference was found between the plasma arterial and venous levels of 18F. There was an excellent correlation between MRGlu estimated using an arterial input function and a population-derived input function scaled using a single arterialised venous blood sample (r(2)=0.98, n=12). The method was reproducible with less than 4.4% variation between repeat tumour scans. Therefore, a population-derived input function scaled using a single arterialised venous blood sample at 20 min can be used for estimating MRGlu using 18F-FDG PET in glioma patients.     

Routine brain imaging is unwarranted in asymptomatic patients with rhabdomyosarcoma arising outside of the head and neck region that is metastatic at diagnosis: a report from the Intergroup Rhabdomyosarcoma Study Group.

BACKGROUND: To the authors' knowledge, the incidence of brain metastases at the time of diagnosis in children with metastatic rhabdomyosarcoma (RMS) arising outside the head and neck region is unknown, and routine imaging to identify metastatic brain involvement is costly. METHODS: The authors retrospectively reviewed the results of computed tomography (CT) or magnetic resonance imaging (MRI) scans of the head, which was mandated by protocol, in patients with metastatic RMS arising outside the head and neck region who were enrolled on the fourth Intergroup Rhabdomyosarcoma Study (IRS-IV; 1991--1997). RESULTS: Of 100 eligible patients with metastatic RMS arising outside the head and neck region, 56 (56%) underwent head CT (n = 51) and/or MRI (n = 11) scans. Seven of these 56 patients (12.5%) had abnormal scans. Three patients with physical findings suggesting head or neck pathology underwent imaging that confirmed the presence of metastases in bone (one patient), orbit (one patient), or lymph nodes (one patient). One patient who presented with seizures had imaging findings consistent with cerebral embolic infarctions. Of three asymptomatic patients, one had bone metastases that also were identified on skeletal survey and one had bone metastases in the base of the skull that were not identified on bone scan. The remaining asymptomatic patient had a retroperitoneal paraspinal tumor with spinal canal extension and subsequently developed leptomeningeal disease dissemination. CONCLUSIONS: Brain metastases are uncommon at the time of initial diagnosis of metastatic RMS arising outside the head and neck region, and the majority of abnormalities detected on head CT or MRI scans are evident clinically or on other imaging studies. Patients with clinical findings suggesting intracranial pathology and those with paraspinal tumors may benefit from brain imaging, but cost savings may be realized by foregoing imaging in patients without these features.     

头颈部炎性肌纤维母细胞瘤的影像表现及临床特点

  目的  探讨头颈部炎性肌纤维母细胞瘤的影像学表现及临床特征,提高该病的术前诊断水平。  方法  回顾性分析收治11例病理确诊头颈部炎性肌纤维母细胞瘤患者的临床特征以及CT、MRI表现。  结果  11例患者中8例临床上表现为进行性增大的无痛性头颈部肿块,2例表现为面部肿胀,1例表现为进行性眼球突出,72.7%（8/11）在术前临床诊断为恶性肿瘤。11例患者均在术前行CT或MRI检查,其中6例行MRI检查,3例行CT检查,2例同时行CT和MRI检查。头颈部炎性肌纤维母瘤在CT和MRI上表现与恶性肿瘤相近。11例患者共发现15个病灶,其中86.7%病灶（13/15）边界不清楚,侵犯临近肌肉,46.7%（7/15）病灶有骨质侵犯。3例患者出现神经孔道侵犯,其中2例为发生于咀嚼肌间隙病灶沿圆孔和卵圆孔向颅内侵犯,1例为发生于眼眶视神经管侵犯。头颈部炎性肌纤维母瘤在CT平扫时呈稍低密度,增强扫描呈明显强化。在MRI上表现为:T1W上呈稍低于肌肉信号,在T2WI上信号强度低于或等于信号肌肉,信号明显不均匀,增强扫描呈明显不均匀强化。  结论  头颈部炎性肌纤维母细胞瘤在临床表现及影像学特征上与恶性肿瘤相近。但是MRI可以在一定程度上反映病灶的组织构成,对诊断和鉴别诊断具有重要作用。      

肉瘤样恶性间皮瘤的CT与MRI表现

目的 探讨肉瘤样恶性间皮瘤的CT与MRI表现特征.方法 回顾性分析6例经病理证实的肉瘤样恶性间皮瘤的CT与MRI资料.5例发生在胸膜,1例发生在腹膜.所有病例均行CT平扫加增强扫描,1例行MRI平扫加增强扫描.结果 5例胸膜肉瘤样恶性间皮瘤全部发生在左胸,广泛不规则胸膜增厚、胸腔积液.其中,3例形成巨大软组织肿块,平扫密度不均,增强明显不均匀强化;1例伴纵隔多发淋巴结肿大.1例腹膜肉瘤样恶性间皮瘤表现为大量腹腔积液,腹膜不规则增厚,形成巨大软组织肿块,平扫密度不均,增强不均匀强化,腹腔、腹膜后多发淋巴结肿大.MRI表现为不规则软组织肿块,T1加权像(T1 weighted imaging,T1 WI)等低信号、T2抑脂高信号,扩散加权成像(diffusion wighted imaging,DWI)高信号,增强后呈明显不均匀强化.结论 CT与MRI表现能较准确显示肉瘤样恶性间皮瘤的病变特征,对定性诊断有一定的提示作用.     

Staging of renal carcinoma using magnetic resonance imaging at 1.5 Tesla

The preoperative magnetic resonance imaging (MRI) studies of 31 patients with surgically proven renal cell carcinomas obtained with a 1.5 Tesla unit were retrospectively reviewed to assess the accuracy of MRI for staging of tumor. According to the Robson classification 12 patients were found at surgery to have Stage I renal carcinoma, three patients had Stage II, ten had Stage IIIA, one had Stage IIIB, two had Stage IIIC, one had Stage IVA, and two had Stage IVB disease. Twenty-five (81%) of 31 patients were staged correctly by MRI. Clearly MRI showed venous tumor extension without the need for intravenous contrast administration. Also, MRI had a negative predictive value of 95%, and a positive predictive value of 100% for the evaluation of inferior vena cava tumor thrombus. At 1.5 Tesla MRI is an excellent staging modality in the preoperative evaluation of renal carcinoma. It is especially recommended in patients with equivocal computed tomography findings and in all patients with contraindications to the intravenous use of iodinated contrast material.     

Pyogenic abscess complicating a resolving cerebral haematoma secondary to a cavernous haemangioma: Computed tomography and magnetic resonance imaging findings

A case is discussed of a brain abscess complicating an intracerebral haemorrhage occurring in a cavernous haemangioma. A young child presented with focal seizures as a result of a large intracerebral haemorrhage, occurring in a cavernous haemangioma. The only clue to the underlying vascular malformation was the presence of an associated developmental venous anomaly. The case was complicated by the development of a brain abscess at the site of the intracranial haematoma. The CT and MRI findings are discussed.     

鼻咽癌放射治疗后FDG PET显像的临床价值

目的 探讨核医学影像诊断技术--FDG PET在鼻咽癌放射治疗后随诊中的临床价值。方法 12例鼻咽癌患者放射治疗后12～18个月同期行FDG PET和CT、MRI检查,并采用双盲法将PDG PET与CT和MRI结果进行比较,其中6例经活检病理证实,余6例经CT动态观察10个月后确诊。结果 9例CT和MRI未见肿瘤复发,PET显示其中3例有局灶性FDG代谢明显增高病变,2例CT和MRI提示肿瘤复发,FDG PET均显示局部病变有放射性摄取浓聚;该5例FDG摄取浓聚的病变处均经活检病理证实为肿瘤复发。另1例MRI提示鼻咽癌颅内转移,而FDG PET诊断为放射治疗后脑损伤,后经CT随访证实。结论 与CT和MRI检查相比,FDG PET在鼻咽癌放射治疗后肿瘤复发的早期定性诊断上具有明显的优势,若结合CT和MRI多种影像结果分析,更能提供局部病变结构与代谢改变的复合信息,尤其对局部复发病灶精确的适形放射治疗非常重要。     

Validation of neuroradiologic response assessment in gliomas: measurement by RECIST, two-dimensional, computer-assisted tumor area, and computer-assisted tumor volume methods

Significant limitations are associated with the use of standard radiographic measurements as indicators of response in glioma therapy trials. The Response Evaluation Criteria in Solid Tumors (RECIST) were recently introduced in an attempt to standardize and simplify assessment of response to treatment in cancer clinical trials. However, their applicability in gliomas has been assessed in only a very small number of patients. Our aim was to validate radiographic response assessment in newly diagnosed glioma patients. Sixty-seven newly diagnosed glioma patients participating in nine North Central Cancer Treatment Group glioma trials were included; 565 MRI scans were analyzed. All scans were performed with the same technique. Kappa statistics were calculated to determine agreement between assessment methods. Cox proportional hazards analyses and time-dependent Cox models were used to assess the association between different measurement methods and overall survival. Results showed agreement between the one-dimensional (1D) and two-dimensional (2D) measurements both for T2 images and for gadolinium-enhanced images. Comparison of duration of response and time to progression as assessed by eight different methods showed similarity in response assessments by 1D, 2D, area, and volume gadolinium measurements. In contrast, time to progression was significantly shorter when assessed by 1D-T2 or 2D-T2 images as compared to area-T2 or volume-T2 images. This set of data indicates that RECIST could be used instead of 2D imaging for response assessment in newly diagnosed glioma trials. Overall, responses as determined by any tumor measurement method did not correlate with patient survival for either enhancing or nonenhancing tumors, although the small number of responders limits definitive conclusions. Time-dependent Cox models demonstrated that, in contrast to the case of nonenhancing tumors, progression as determined by 1D, 2D, area, and volume measurements in gadolinium-enhanced images was predictive of survival of patients with enhancing tumors.     

Characterization of a human tumorsphere glioma orthotopic model using magnetic resonance imaging

Magnetic resonance imaging (MRI) is the imaging modality of choice by which to monitor patient gliomas and treatment effects, and has been applied to murine models of glioma. However, a major obstacle to the development of effective glioma therapeutics has been that widely used animal models of glioma have not accurately recapitulated the morphological heterogeneity and invasive nature of this very lethal human cancer. This deficiency is being alleviated somewhat as more representative models are being developed, but there is still a clear need for relevant yet practical models that are well-characterized in terms of their MRI features. Hence we sought to chronicle the MRI profile of a recently developed, comparatively straightforward human tumor stem cell (hTSC) derived glioma model in mice using conventional MRI methods. This model reproduces the salient features of gliomas in humans, including florid neoangiogenesis and aggressive invasion of normal brain. Accordingly, the variable, invasive morphology of hTSC gliomas visualized on MRI duplicated that seen in patients, and it differed considerably from the widely used U87 glioma model that does not invade normal brain. After several weeks of tumor growth the hTSC model exhibited an MRI contrast enhancing phenotype having variable intensity and an irregular shape, which mimicked the heterogeneous appearance observed with human glioma patients. The MRI findings reported here support the use of the hTSC glioma xenograft model combined with MRI, as a test platform for assessing candidate therapeutics for glioma, and for developing novel MR methods.     

Intraoperative use of an open mid-field MR scanner in the surgical treatment of cerebral gliomas

The aim of the present study was to evaluate the effectiveness of intraoperative MRI guidance in achieving more gross-total resection in case of primary brain tumors. We studied 12 patients with low-grade glioma and 19 patients with high-grade glioma who underwent surgery within a vertically open 0.5 T MR system. After initial imaging, the resection was stopped at the point in which the neurosurgeon considered the resection complete by viewing the operation field. At this time, intraoperative MRI was repeated ("first control") to identify any residual tumor. Areas of tumor-suspected tissue were localized and resected, with the exception of tissue adjacent to eloquent areas. Final imaging was carried out before closing the craniotomy. Comparison of "first control" and final imaging revealed a decrease of residual tumor volume from 32% to 4.3% in low-grade gliomas, and from 29% to 10% in high-grade gliomas. Intraoperative MRI allows a clear optimization of microsurgical resection of both low-grade and high-grade gliomas.