Cerebral tumor embolism from thyroid cancer treated by mechanical thrombectomy: illustrative case.

BACKGROUND: Development in mechanical thrombectomy is progressing dramatically. Tumor embolism has been rarely reported on the basis of pathological study of the retrieved thrombus. Herein, the authors report a case of cerebral tumor embolism from advanced thyroid cancer, which was successfully treated with mechanical thrombectomy. OBSERVATIONS: A 57-year-old man was diagnosed with thyroid cancer with multiple lung metastases and chemotherapy was planned. He experienced left hemiparesis and was bought to the emergency section of the authors' hospital. Magnetic resonance angiography revealed right internal carotid artery occlusion and endovascular treatment was performed. Using a combination of aspiration catheter and stent retriever, white jelly-like embolus was retrieved. The pathological study demonstrated thyroid cancer embolism. Pulmonary vein invasion following lung metastasis of thyroid cancer was most presumably the cause of the tumor embolism. LESSONS: Lung metastasis invading the pulmonary vein may be a cause of tumor embolism. Mechanical thrombectomy using a combination of stent retriever and aspiration catheter is effective in removing the tumor embolus and the pathological examination of the embolus is essential.

Factors associated with the location of perivascular space enlargement in middle-aged individuals undergoing brain screening in Japan.

OBJECTIVE: In elderly populations, the enlargement of the perivascular space is related to small vessel disease and the glymphatic system. Enlarged perivascular spaces (EPVS) in the basal ganglia (EPVS-BG) and EPVS in the centrum semiovale (EPVS-CSO) are associated with different pathophysiological processes. However, the prevalence of EPVS and the factors associated with EPVS location in healthy middle-aged individuals are still unclear. We aimed to determine the prevalence of EPVS and the factors associated with EPVS location among healthy individuals in their 40 s METHODS: This study included 5000 consecutive healthy individuals who underwent screening for brain diseases in Japan from August to December 2018. Of them, the data of individuals in their 40 s were extracted and analyzed. The associations of age, sex, body mass index, smoking and drinking history, and medical history with EPVS location were investigated. Similar analyses were performed for the other age groups. A literature review on the factors associated with EPVS location was also performed. RESULTS: A total of 1720 individuals in their 40 s were finally included. The prevalence of EPVS-BG and EPVS-CSO was 7.7% and 9.2%, respectively. Age (years), smoking history, and hypertension were associated with EPVS-BG; none of the studied factors were found to be associated with EPVS-CSO. In the elderly, the factors previously reported to be associated with EPVS-BG included atherosclerosis change, while the factors associated with EPVS-CSO were cerebral amyloid angiopathy-related formation. CONCLUSION: Both EPVS-BG and EPVS-CSO occurred among healthy individuals in their 40 s, but they did so rarely, and less prevalently than in older age groups. EPVS-BG and EPVS-CSO may represent early imaging signs of the atherosclerotic and cerebral amyloid angiopathy processes, respectively. DATA AVAILABILITY: The anonymized data for this study will be shared upon any qualified investigator's request to the corresponding author. Primary data from this study will be made available upon reasonable request in accordance with the review board of the research institute.

Metastatic Brain Tumor in the Cerebellopontine Angle from Gastric Cancer: A Case Report.

Cerebellopontine angle (CPA) tumors are a common type of benign tumors, which are similar to vestibular schwannomas; however, the incidence of CPA metastasis is rare. Moreover, brain metastasis from gastric tumors is a rare occurrence, with an incidence of less than 1% in clinical cases. In this study, we report the case of a 71-year-old man who was admitted to our hospital with symptoms of nausea and gait instability for the past 1 week. He had no remarkable medical history. Magnetic resonance imaging revealed a tumor in the left CPA. Intraoperative diagnosis indicated the presence of metastatic papillary carcinoma. Postoperatively, gastric endoscopy revealed a protruding mass on the cardia of the stomach, which was histopathologically similar to that of the resected brain tumor. The patient underwent adjuvant cyberknife radiotherapy and chemotherapy. A prompt biopsy of the brain tumor is essential if any findings suggest malignancy.

Frameless Free-Hand Navigation-Guided Biopsy for Brain Tumors: A Simpler Method with an Endoscope Holder.

CONTEXT/AIMS: Given the limitations of current navigation-guided brain biopsy methods, we aimed to introduce a novel method and validate its safety and accuracy. SETTING AND DESIGN: This was a retrospective study of twenty consecutive patients who underwent brain biopsy at Shimane University Hospital, Japan. SUBJECTS AND METHODS: Clinical records of 13 and 7 patients who underwent brain biopsy with the novel frameless free-hand navigation-guided biopsy (FFNB) method or a framed computed tomography-guided stereotactic biopsy (CTGB) method, respectively, were retrospectively reviewed. We compared age, sex, tumor location, histological diagnosis, maximum size of the tumor (target), depth from target to cortical surface on the same slice of CT or magnetic resonance imaging, operative position, anesthesia method, setup time for biopsy, incision-to-closure time, trial times for puncture, success rate, and complications in the two groups. STATISTICAL ANALYSIS: Fisher's exact test and the Wilcoxon rank-sum test were performed. RESULTS: Clinical characteristics and lesion size did not differ significantly between the FFNB and CTGB groups. The depth of the target lesion was significantly greater in the CTGB group (P < 0.05). All FFNB and CTGB procedures reached and obtained the target tissue. The number of punctures and the average incision-to-closure time did not differ between the FFNB and CTGB groups. However, the preoperative setup time was significantly shorter using FFNB (P = 0.0003). No complications were observed in either group. CONCLUSIONS: FFNB was comparable with CTGB in terms of safety, accuracy, and operative duration. The preoperative setup time was shorter using FFNB. Therefore, FFNB is a feasible method for brain tumor biopsy.

Aggressive Intraoperative Cisternal Clot Removal After Clipping Aneurismal Subarachnoid Hemorrhage in Elderly Patients.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) in the elderly often has a poor prognosis even after surgical treatment in the acute phase. Additionally, subarachnoid clots are the strongest predictors of cerebral vasospasm and tend to be thicker and heavier due to cerebral atrophy. We aimed to compare the conventional surgical treatment in such patients and identify the independent predictors of a favorable outcome after aggressive surgical clot removal. METHODS: We included 40 patients with aSAH aged 70 or older. Each patient underwent aneurysmal clipping. We used the modified Rankin Scale to assess the primary outcome of neurologic status at discharge. We performed univariate analysis using the following factors: sex, age, neurologic, and general medical condition, radiographic data, aneurysm location, treatment approach, and timing of the aneurysm surgery. We divided the patients into irrigation and nonirrigation groups. We focused mainly on subarachnoid clots and analyzed them semiquantitatively using computed tomography. RESULTS: Clot removal was significantly greater in the irrigation group (n = 21) than in the nonirrigation group (n = 19). The period of intrathecal drainage was significantly shorter in the irrigation group (P = 0.002). The rate of occurrence of new low-density areas on CT scans was higher in the nonirrigation group. Outcomes were better in the irrigation group (P = 0.010). CONCLUSIONS: In elderly patients with aSAH in the acute phase, aggressive surgical clot removal after clipping showed favorable outcomes by facilitating early out-of-bed mobilization.

Fatal Postpartum Hemorrhage in Diffuse Midline Glioma with H3-K27M Mutation.

Management of pregnant women with brain tumors necessitates difficult decision-making especially for estimating or preventing its intratumoral hemorrhage. A 26-year-old, 19-week pregnant woman complaining of headache and vomiting was admitted to our hospital. Magnetic resonance imaging (MRI) revealed hydrocephalus and a mass lesion without contrast enhancement extending from the left thalamus. To resolve severe symptoms, a ventriculoperitoneal shunt was inserted, and a biopsy was taken via the right ventricle. Pathological examination suggested diffuse or pilocytic astrocytoma, but subsequent genetic analysis revealed the diagnosis of midline glioma with H3-K27M mutation. The patient opted not to terminate the pregnancy, and MRIs conducted every four weeks revealed no change in tumor aspect. The patient delivered a healthy baby by cesarean section, and postpartum day 1 was uneventful. However, she was found in a coma due to a massive intratumoral hemorrhage on postpartum day 2 and died 3 weeks after the hemorrhage. This is the first case report of diffuse midline glioma with H3-K27M mutation in a pregnant woman followed by fatal hemorrhage. It highlights the necessity of careful clinical management and frequent neuroimaging during the entire perinatal period, even if the tumor has hypovascularity or low proliferative potential on radiological or pathological findings.

Ten-Year Follow-Up of Collision Tumors Composed of Craniopharyngioma and Pituitary Adenoma: A Case Report and Literature Review.

Although craniopharyngioma (CP) and pituitary adenoma (PA) are common tumors of the parasellar lesions, the coexistence of CP and PA is very rare. A 48-year-old male visited our hospital because of consciousness disturbance. The neuroimaging revealed a sellar tumor contact with a massive suprasellar cyst including calcification. Preoperative diagnosis was CP, and the patient underwent craniotomy to resolve the suprasellar mass effect. The histological examination disclosed adamantinomatous CP, and subsequently a transsphenoidal approach was chosen for the residual intrasellar tumor. Against expectations, the histological diagnosis was not CP but PA. The patient underwent gamma knife surgery for the residual tumor, and the postoperative course was good. After a 10-year follow-up, both lesions were still completely controlled. If we had suspected and diagnosed the tumor involved as not only CP but also PA at the first operation, the second operation could have been avoided because we would have chosen gamma knife surgery for the residual tumor. We should draw attention to this rare situation for differential diagnosis of parasellar tumor to avoid unnecessary surgery and to decide the best strategy for treatment. In addition, the biological behavior of collision tumors composed of CP and PA is probably the same as solitary CP or PA based on a long-term follow-up of our case.

[A Case of Metastatic Peripheral T-cell Lymphoma of the Central Nervous System During the Perinatal Period].

The diagnosis of malignant tumors during pregnancy is not uncommon; the incidence is one per six thousand pregnancies. However, the diagnosis of malignant lymphoma-especially T-cell lymphoma-during pregnancy is extremely rare. Thus, the early detection and management of T-cell lymphoma necessitates difficult decision-making. A 30-year-old woman developed consciousness disturbance on postpartum day three. Because brain MRI showed multiple edematous lesions in both hemispheres, vasculitis or encephalitis was initially suspected, and diagnostic therapy was initiated with the administration of steroids. One month later, the patient suddenly developed a subarachnoid hemorrhage followed by acute hydrocephalus. Emergent ventricular drainage and lesion biopsy were simultaneously performed. Based on the findings, the patient was diagnosed with peripheral T-cell lymphoma not otherwise specified(PTCL-NOS). Laboratory findings indicated Epstein-Barr virus(EBV)infection. Moreover, the same diagnosis was supported by breast and bone marrow biopsies. Thus, the brain lesions were presumed to be metastatic in nature. The prognosis of PTCL-NOS is severely poor in pregnant women as diagnosis is delayed owing to limitations of radiological examinations and because symptoms can be confused with those of other diseases or hyperemesis gravidarum. Additionally, the alteration of immunotolerance in association with pregnancy and EBV infection might have influenced the aggressive features of this case. When a pregnant woman presents with neurological symptoms, malignant lymphoma should be considered when making a differential diagnosis.

Pyothorax-associated Angiosarcoma Metastasized to the Brain with Multiple and Progressively Expanding Hematomas: Case Report and Literature Review.

The brain metastasis of angiosarcoma is very rare, and little is known about its clinical features or therapeutic strategy. A 74-year-old male was hospitalized for disturbance of consciousness. Radiological examination revealed multiple cerebral hematomas. Gadolinium contrast-enhanced magnetic resonance imaging showed no significant enhancement at any of the lesions. To detect a suspected metastatic brain tumor or abscess, a full-body scan was performed but revealed only a poorly enhanced mass in the removal cavity caused by thoracoplasty in the left upper chest. After admission, a cascade of expansion of those hematomas occurred in the right frontal, left parietal, and right temporal lobes, and each lesion thus had to be sequentially removed by craniotomies. The pathological diagnosis of the right frontal lesion was an abscess with hematoma. However, a malignant vascular tumor was highly suspected because of many CD31(+)/Ki-67(+) cells in the left parietal lesion. A mass in the scar caused by thoracoplasty was suspected to be the primary lesion, and brain metastasis of angiosarcoma was finally diagnosed. Whole-brain irradiation and systemic paclitaxel administration were performed, and a complete response for the brain lesions was obtained for 22 months; the patient then died of an intratracheal hemorrhage. This case represents the first report of multiple brain metastases from pyothorax-associated angiosarcoma accompanied by sequentially and gradually expanding hematomas, as well as the first case with the control of metastatic brain lesions for over 1 year after the onset of neurological symptoms. Control of the lesions could be achieved by their total removal with complete hemostasis, as well as additional radio- and chemotherapy.

[A case of repeated shunt malfunctions with eosinophilic meningitis caused by silicone allergy].

The ventricular-peritoneal shunt for hydrocephalus is a well-known and established method but is sometimes complicated by shunt malfunction due to several causes. Eosinophilic meningitis is a rare disease, but has occasionally been reported as a cause of shunt malfunction. Here, we report the case of a 74-year-old woman with repeated shunt malfunction and eosinophilic meningitis due to a silicone allergy. Originally, the patient received a ventricular-peritoneal shunt for normal pressure hydrocephalus secondary to subarachnoid hemorrhage. However, shunt malfunction was identified 6 weeks later, and the first shunt revision was performed using a new shunt system from a different company. Further evaluation to identify the cause of the shunt malfunction revealed no abnormal findings, except for eosinophilia in the serum and cerebrospinal fluid. A second shunt malfunction was identified 16 weeks after the first shunt revision. We therefore concluded that eosinophilic meningitis caused by a silicone allergy might be the real culprit and a second shunt revision was performed using a silicone "extracted" tube. Since then, the patient's course has been free from shunt malfunction. In this case, the serum and cerebrospinal fluid eosinophilia were useful markers for identifying the cause of repeated shunt malfunctions. The silicone "extracted" tube may be helpful for diagnosis and therapy.

Rathke's cleft cyst with non-hemorrhagic rupture resulting in alteration of signal intensity for a short period: a case report.

In a case of 23-year-old female with Rathke's cleft cyst (RCC), unusual changes with size and morphology on computed tomography (CT) and magnetic resonance images (MRI) were noted in a short period of 3 weeks after spontaneous rupture. The CT noted that the intracystic isodensity was changed to hyperdensity. And MRI showed not only a decrease in size of the lesion but also changing from hypo- and hyperintensity in T1- and T2-weighted images to hyperintensity in both T1- and T2-weighted images. The intraoperative findings disclosed that the cyst content was milky-like, but not hemorrhagic. We considered that the leakage of cyst content to the cerebrospinal fluid pathway caused not only inflammatory reaction but also waxing and waning of both the cyst size and intralesional protein concentration, which resulted in unusual changing CT and MR appearance. We should take into consideration that the nature of RCC can be altered by not only intracystic hemorrhage but also non-hemorrhagic rupture even for a short period.

[A case of HELLP syndrome resulting in eclampsia with non-aneurysmal subarachnoid hemorrhage].

It is known that hemorrhagic stroke at the perinatal period are caused by specifics conditions like eclampsia as well as by the existing abnormal vessels. We treated a case of HELLP syndrome resulting in eclampsia with non-aneurysmal, convexity subarachnoid hemorrhage. A 34-year-old female, who had been pointed out to have a high level of urinal protein at the 37th week, was seen in the emergency department because of severe headache, vomiting and respiratory discomfort. Her systolic blood pressure was over 190mmHg, and caesarean section was selected. On the way to the operating room, she had a generalized convulsion with loss of consciousness. The delivery was carried out. The CT immediately after the caesarean section revealed faint and localized subarachnoid hemorrhage in the bilateral convexity areas. Additionally, the FLAIR image of MRI demonstrated increased intensity in the bilateral cerebellar hemispheres, basal ganglion and subcortical area, suggesting vasogenic edema. The patient had a good clinical course and the abnormal signal of MRI also recovered by treatment with oral iron and zinc. Here, we report a speculation for the mechanism of this case and precautions against stroke in the perinatal period.

[Elastic modulus measured by spherical indentation used toward the clinical application of the brain stiffness].

OBJECTIVE: Palpation of brain stiffness is one of techniques that leads to successful neurosurgical procedures. In order to evaluate brain stiffness quantitatively, we studied the potential clinical applicability of a spherical indenting tactile sensor. METHODS: The sensor had a spherical rigid indenter (diameter=5.0 mm; contact pressure=1.0 gf/mm2), and the indenter was rapidly pushed and pulled at a constant speed by a computer-controlled motor. The pressure-depth hysteresis curve was obtained using the sensor, and the shear elastic modulus (G) was calculated on the basis of the Hertz contact theory. We adopted the G-value at the maximum depth (G_max) as an indicator of brain stiffness. RESULTS: First, to calibrate the sensor, we investigated the elasticity of silicone plates. The optimal settings for clinical application was an indenting speed of 1.5 mm/s and an indenting maximum depth of 2-3 mm. Next, we measured the elasticity of a decompressive site in 7 patients who had been stable for more than 21 days after undergoing decompressive craniectomy. The G_max of the decompressive site was 1.71 ± 0.75 kPa. Finally, we measured the intraoperative brain elasticity in a case of brain tumor with severe brain edema. The transdural elasticity of the edematous brain was G=4.87 kPa, and the direct elasticity of the brain surface decreased to G=4.34 kPa after dura incision. CONCLUSIONS: The spherical indentation method for measuring brain elasticity seems applicable to neurosurgical procedures.

Improvement of the (99m)Tc-ECD brain uptake ratio (BUR) method for measurement of cerebral blood flow.

OBJECTIVE: The brain uptake ratio (BUR) method for the (99m)Tc-ECD SPECT, a non-invasive measurement method of rCBF, has been used in clinical practice in Japan, because it is simple to use. However, the accuracy of this method is limited, as it has problems in the determination of input function and the regression equation. The purpose of this study is to improve the BUR method by reconstructing the determination process of the input function and regression equation based on measurement of the rCBF by H (2) (15) O PET. METHOD: The input function was obtained by setting the region of interest on the ascending aorta instead of the aortic arch. The 3DSRT algorithm was used to obtain the anatomically standardized rCBF, and developed a semi-automatic analyzing software using C++ in order to stabilize the repeatability of the improved BUR (IBUR) method. The regression equation for the IBUR method was obtained by the H (2) (15) O PET rCBFs in 15 patients with the arterial blood sampling method. All the measurements in this study were performed with the patient in the resting state. RESULT: A good correlation was observed between the rCBF values measured by H (2) (15) O PET and the regional BURs measured by the IBUR method (r = 0.86, p < 0.0001). The rCBF values were calculated for only 5 min using a semi-automatic analyzing software. CONCLUSION: The BUR method was improved by changing the location of the input function from the aortic arch to the ascending aorta based on arterial blood flow dynamics, and reconstructing regression equation based on the rCBF values obtained using H (2) (15) O PET. This finding indicates the potential clinical usefulness of this method.

Postoperative quality of life outcome and employment in patients undergoing resection of epileptogenic lesions detected by magnetic resonance imaging.

The long-term postoperative improvement of quality of life (QOL) and employment were investigated in patients undergoing resection of epileptogenic lesions detected by magnetic resonance (MR) imaging to identify the associated preoperative factors. Thirty of 47 patients who underwent lesionectomy between 1987-2001 replied to questionnaires. Patients with extratemporal resection outnumbered those with temporal lobe resection. The mean follow-up period was 12.4 +/- 3.7 years. An arbitrary score for quantitatively assessing QOL was assigned. The mean increases in QOL score points were significantly higher in the late childhood onset group than those in the early childhood onset group, and were also significantly higher in the temporal resection group and extratemporal resection of non-dysplastic cortical pathology group than in the extratemporal resection of dysplastic cortical pathology group. Postoperative QOL improvement and occupational status of patients depended on the completeness of seizure control. Resection of lesions detected by MR imaging in patients with intractable epilepsy resulted in effective long-term QOL improvement and postoperative occupational status. Favorable outcome was related mainly to the pathology of the epileptogenic lesions, whether the lesion site was temporal or extratemporal, and the completeness of seizure control.

Stage-specific effect of inhibition of autophagy on chemotherapy-induced cytotoxicity.

Anticancer therapies can induce autophagy in tumor cells and the role of autophagy in these cells may depend on the type of tumor, the stage of tumorigenesis, and the nature and extent of the insult. Appropriate modification of autophagy, that is, suppression of cell-protective autophagy or enhancement of cell-killing autophagy could augment cytotoxicity caused by anticancer therapy. Imatinib mesylate is an inhibitor of tyrosine kinases and is used for the therapy of patients with tumors including leukemias, but is not effective as a monotherapy for malignant glioma. To seek a strategy to augment the therapeutic efficacy of imatinib, we examined the mode of cytotoxicity of imatinib in human malignant glioma cells. Since imatinib induced cytotoxicity associated with autophagy, we tested the effect of inhibition of autophagy on imatinib-induced cytotoxicity. We found that imatinib-induced cytotoxicity is attenuated by inhibition of autophagy at an early stage but augmented by inhibition of autophagy at a late stage through increasing apoptosis following mitochondrial damage. Though the mechanism of the stage-specific effect of inhibiting autophagy on cytotoxicity remains to be elucidated, our findings could be useful for developing a new strategy to enhance the efficacy of anticancer therapy by modulating autophagy.

Indoleamine 2,3-dioxygenase as a new target for malignant glioma therapy. Laboratory investigation.

OBJECT: Indoleamine 2,3-dioxygenase (IDO), a kynurenine pathway (KP) enzyme catalyzing oxidation of the essential amino acid tryptophan (Trp), is thought to be involved in the immune resistance of malignant tumors through T-cell inactivation caused by Trp depletion and metabolite accumulation. Human malignant gliomas may use this strategy to escape immune attack. The object of this study was to investigate the possibility of IDO-dependent Trp depletion by malignant gliomas and the practicability of using an IDO inhibitor together with anticancer drugs to reserve Trp without decreasing the cytotoxicity of the drugs. METHODS: The authors studied expression of IDO and other KP enzymes and the effects of an IDO inhibitor, 1-methyl L-tryptophan (1MT), on Trp metabolism and cytotoxicity of anticancer drugs, together with direct measurement of KP metabolites, in cultured human malignant glioma cells. RESULTS: Upon interferon-gamma (IFN-gamma) stimulation, the glioma cells greatly increased their IDO mRNA expression concomitant with depletion of Trp. The IDO inhibitor 1MT successfully prevented Trp consumption by the stimulated glioma cells. Combining 1MT with anticancer drugs (temozolomide, bischloroethylnitrosourea [BCNU], etoposide and cisplatin) did not interfere with the drugs' suppression of growth of LN229 glioma cells but rather increased their inhibitory effects on IDO activity. CONCLUSIONS: These findings suggest that the robust IDO expression with rapid consumption of Trp in human glioma cells induced by IFN-gamma could lead to immune resistance in glioma cells. Indoleamine 2,3-dioxygenase inhibitors that prevent Trp depletion could be used with anticancer drugs to improve therapeutic effects.

Inhibition of autophagy at a late stage enhances imatinib-induced cytotoxicity in human malignant glioma cells.

Malignant gliomas are common primary tumors of the central nervous system. The prognosis of patients with malignant glioma is poor in spite of current intensive therapy and thus novel therapeutic modalities are necessary. Imatinib mesylate, a tyrosine kinase inhibitor, is effective in the therapy of tumors including leukemias but not as a monotherapy for malignant glioma. Recently, it is thought that the adequate modulation of autophagy can enhance efficacy of anticancer therapy. The outcome of autophagy manipulation, however, seems to depend on the autophagy initiator, the combined stimuli, the extent of cellular damage and the type of cells, and it is not yet fully understood how we should modulate autophagy to augment efficacy of each anticancer therapy. In this study, we examined the effect of imatinib with or without different types of autophagy inhibitors on human malignant glioma cells. Imatinib inhibited the viability of U87-MG and U373-MG cells in a dose dependent manner and caused nonapoptotic autophagic cell death. Suppression of imatinib-induced autophagy by 3-methyladenine or small interfering RNA against Atg5, which inhibit autophagy at an early stage, attenuated the imatinib-induced cytotoxicity. In contrast, inhibition of autophagy at a late stage by bafilomycin A1 or RTA 203 enhanced imatinib-induced cytotoxicity through the induction of apoptosis following mitochondrial disruption. Our findings suggest that therapeutic efficiency of imatinib for malignant glioma may be augmented by inhibition of autophagy at a late stage, and that appropriate modulation of autophagy may sensitize tumor cells to anticancer therapy.

[Quantitative assessment of the usefulness of MR-fusion Tl-SPECT image in the diagnosis of brain tumor].

201Tl-SPECT (single photon emission computed tomography) had a disadvantage of low spatial resolution with a limited ROI (region of interest) setting. Recently, the diagnosis of brain tumors has been improved by fusion-imaging employing MRI (magnetic resonance imaging) with Tl-SPECT. In order to assess the usefulness of MR-fusion Tl-SPECT quantitatively, we have compared non-fusion (NF) and MR-fusion (MR-F) imaging with Tl-SEPCT in patients with brain tumors. A total of 38 patients (M/F=14/24) hospitalized at our institution during a 5-year period, each with a histologically confirmed brain tumor, were studied. The index of Tl was used for the early ratio (ER), delayed ratio (DR), and retention index (RI), There was no significant difference between NF and MR-F, which were examined using the test-retest method by 2 observers (N&H), but the Pearson's correlation coefficient was higher for MR-F than for NF. The RI value for MR-F was significantly correlated with the WHO histological grading (r=0.605, n=38, p<0.00l). The DR value for MR-F was significantly correlated with MIB-1 index (r=0.464, n=24, p=0.022). We estimated the RI cut-off value for both NF and MR-F in malignancy by ROC analysis. A cut-off value of RI=0.63 and RI=0.70 was good for NF and MR-F, respectively. The likelihood ratio (LR) of RI was higher for MR-F (LR=6.897) than for NF (LR=2.978), suggesting that RI=0.7 for MR-F was suitable for diagnosis of malignant brain tumor. We conclude that MR-fusion Tl-SPECT is better for quantitative analysis of brain tumors than non-fusion Tl-SPECT.