Yoshitaka Asano

Surgical treatment of cavernous angioma involving the brainstem and review of the literature

SummaryFive cases of symptomatic cavernous angioma involving the brainstem are reported. Magnetic resonance (MR) imaging is of greatest value in the diagnosis and for surgical indication. All cases were treated by radical extirpation. All of them improved postoperatively. The surgical indications for this lesion of the brainstem are briefly discussed with a review of the literature, including 28 previous cases, operated on directly.

THE CHARACTERIZATION OF HUMAN BRAIN TUMOR USING MAGNETIZATION TRANSFER TECHNIQUE IN MAGNETIC RESONANCE IMAGING

The clinical applicability of magnetization transfer (MT) technique in magnetic resonance imaging (MRI) for the estimation of the histological and constitutional feature of brain tumors was investigated. MT effect was evaluated by measuring the MT ratio (MTR). The parameters in 1.5-tesla MRI system were as follows: TR, 50 msec; TE, 5 msec; flip angle, 30 degree; offset frequency of off-resonance MT pulse, 1000 Hz. The sequence was performed in 20 normal volunteers and 45 patients with brain tumors which were characterized histologically and surgically. The MTR for brain tumors was significantly lower than that for normal brain tissue (p < 0.05). The MTR for meningioma was higher than that for the other brain tumors (p < 0.05). In the meningiomas, MTR for fibrous type was higher than that for meningothelial type, but there was no statistical significance. Regarding the physical consistency for the brain tumors, as classified by surgery, there was a statistically significant difference in MTR between the soft tumor group (0.22 +/- 0.03, n = 6) and the hard tumor group (0.36 +/- 0.04, n = 10) (p < 0.01). This study suggested that the MT technique for patients with brain tumor may be useful to understand the characteristics of the tumors presurgically, based on the degree of intermolecular interaction of macromolecule such as protein.

Metabolic assessment of monofocal acute inflammatory demyelination using MR spectroscopy and 11C-methionine-, 11C-choline-, and 18F-fluorodeoxyglucose-PET

Monofocal acute inflammatory demyelination (MAID), which is observable by CT and MRI as a well-enhanced mass lesion with prominent perifocal edema, is very similar to malignant gliomas radiologically, making differential diagnosis of the two pathologies difficult. The aim of this study was to assess the different metabolic activities between MAID and malignant gliomas by MRS, methionine-PET, choline-PET, and FDG-PET. Six patients with MAID underwent methionine, choline, and FDG-PET, and 4 of the patients also underwent magnetic resonance spectroscopy (MRS). The images obtained from these patients were compared with the corresponding images of 19 anaplastic astrocytomas (AA) and 21 glioblastomas (GBM). The mean choline/creatine ratio of MAID was significantly lower than that of GBM. There were no significant differences in the mean NAA/creatine and lactate/creatine ratios among these pathologies. The methionine T/N ratio of MAID was significantly lower than those of AA and GBM. The choline T/N ratio of MAID was significantly lower than that of GBM. There were no significant differences in the FDG T/N ratios among these pathologies. These results demonstrate that the metabolic activity of MAID significantly differs in part from that of malignant gliomas. Combined PET and MRS neuroimaging examinations may be useful for differential diagnosis of these pathologies.

Fate of graft cells: what should be clarified for development of mesenchymal stem cell therapy for ischemic stroke?

Mesenchymal stem cells (MSCs) are believed to be promising for cell administration therapy after ischemic stroke. Because of their advantageous characteristics, such as ability of differentiation into neurovascular lineages, avoidance of immunological problems, and abundance of graft cells in mesodermal tissues, studies regarding MSC therapy have increased recently. However, several controversies are yet to be resolved before a worldwide consensus regarding a standard protocol is obtained. In particular, the neuroprotective effects, the rate of cell migration to the lesion, and differentiation direction differ depending on preclinical observations. Analyses of these differences and application of recent developments in stem cell biology or engineering in imaging modality may contribute to identification of criteria for optimal stem cell therapy in which reliable protocols, which control cell quality and include safe administration procedures, are defined for each recovery phase after cerebral ischemia. In this mini review, we examine controversies regarding the fate of grafts and the prospects for advanced therapy that could be obtained through recent developments in stem cell research as direct conversion to neural cells.

Hypofractionated high-dose irradiation with positron emission tomography data for the treatment of glioblastoma multiforme.

This research paper presents clinical outcomes of hypofractionated high-dose irradiation by intensity-modulated radiation therapy (Hypo-IMRT) with 11C-methionine positron emission tomography (MET-PET) data for the treatment of glioblastoma multiforme (GBM). A total of 45 patients with GBM were treated with Hypo-IMRT after surgery. Gross tumor volume (GTV) was defined as the area of enhanced lesion on MRI, including MET-PET avid region; clinical target volume (CTV) was the area with 5 mm margin surrounding the GTV; planning target volume (PTV) was the area with 15 mm margin surrounding the CTV, including MET-PET moderate region. Hypo-IMRT was performed in 8 fractions; planning the dose for GTV was escalated to 68 Gy and that for CTV was escalated to 56 Gy, while keeping the dose delivered to the PTV at 40 Gy. Concomitant and adjuvant TMZ chemotherapy was administered. At a median follow-up of 18.7 months, median overall survival (OS) was 20.0 months, and median progression-free survival was 13.0 months. The 1- and 2-year OS rates were 71.2% and 26.3%, respectively. Adjuvant TMZ chemotherapy was significantly predictive of OS on multivariate analysis. Late toxicity included 7 cases of Grade 3-4 radiation necrosis. Hypo-IMRT with MET-PET data appeared to result in favorable survival outcomes for patients with GBM.

Differences in Brain Metabolic Impairment between Chronic Mild/Moderate TBI Patients with and without Visible Brain Lesions Based on MRI.

Introduction. Many patients with mild/moderate traumatic brain injury (m/mTBI) in the chronic stage suffer from executive brain function impairment. Analyzing brain metabolism is important for elucidating the pathological mechanisms associated with their symptoms. This study aimed to determine the differences in brain glucose metabolism between m/mTBI patients with and without visible traumatic brain lesions based on MRI. Methods. Ninety patients with chronic m/mTBI due to traffic accidents were enrolled and divided into two groups based on their MRI findings. Group A comprised 50 patients with visible lesions. Group B comprised 40 patients without visible lesions. Patients underwent FDG-PET scans following cognitive tests. FDG-PET images were analyzed using voxel-by-voxel univariate statistical tests. Results. There were no significant differences in the cognitive tests between Group A and Group B. Based on FDG-PET findings, brain metabolism significantly decreased in the orbital gyrus, cingulate gyrus, and medial thalamus but increased in the parietal and occipital convexity in Group A compared with that in the control. Compared with the control, patients in Group B exhibited no significant changes. Conclusions. These results suggest that different pathological mechanisms may underlie cognitive impairment in m/mTBI patients with and without organic brain damage.

Bedside Clinical Assessment of Consciousness Level in Patients withSevere Chronic Disorders of Consciousness

Conventional medical terms, vegetative state (VS) and minimally conscious state (MCS), for representing consciousness level of chronic disorders of consciousness (DOC) have two problems to use at bedside. One is a nosological issue, and the other is an issue related to scientific usability for clinical assessment. A three-by-two-graded classification, the chronic DOC scale (CDOCS), without any nosologically unfavorable and equivocal words, was established. The consciousness level of 143 patients with severe chronic DOC both at the time of admission and 24 months after the admission were determined using the VS/MCS classification and CDOCS, and the differences of the results of evaluation for improvement between these were assessed. Forty-seven (33%) and 63 (44%) patients were determined as having improved 24 months after admission on the VS/MCS classification and CDOCS, respectively. There was a significant difference in the percentages between these grading systems (p<0.0001). The advantages of CDOCS are that it makes it possible to avoid using uncomfortable and ambiguous terms and that it is superior for evaluating nuanced consciousness level. We recommend the use of CDOCS for bedside assessment of consciousness level in patients with severe chronic DOC as a supplement for the conventional descriptions.

Clinical study of cavernous angioma.

Cryptic vascular malformationの1つであるcavernous angioma (CA) の20例を対象として臨床的検討を加えた.発症年齢は6～75歳平均34歳, 15歳以下5例, 男女比は7対13であった.初発症状は3型に分けられ, 急性巣症状型が40%, 痙攣発作型が40%, その他20%であった.CAはplain CTで95%がhigh densityな病巣として示され, MRIでは全例異常なintensityとして描出され, うち85%がheterogeneousであった.4例は2～26ヵ月の経過観察中再出血や病巣の増大による症状の増悪を示した.CAの局在は天幕上12例, 天幕下5例, 多発3例で, うち5例は脳幹であった.1例は家族発生例であった.全例開頭術によりCAを摘出し, 症状は術前に比べ悪化したものはなく諸症状の改善がみられた.これらの結果から, CAは自然経過において出血を繰返すこと, MRIが診断および摘出術の方法決定に有用であること, 脳幹部発生例でも摘出によって神経諸症状の改善と良好な予後が得られることが示された.