Akimasa Nishio

Methionine positron emission tomography for differentiation of recurrent brain tumor and radiation necrosis after stereotactic radiosurgery--in malignant glioma.

ObjectFollowing stereotactic radiosurgery (SRS), we examined how to differentiate radiation necrosis from recurrent malignant glioma using positron emission tomography (PET) with11C-methionine (Met).MethodsMet-PET scans were obtained from 11 adult cases of recurrent malignant glioma or radiation injury, suspected on the basis of magnetic resonance images (MRI). Patients had previously been treated with SRS after primary treatment. PET images were obtained as a static scan of 10 minutes performed 20 minutes after injection of Met. We defined two visual grades (e.g., positive or negative Met accumulation). On Met-PET scans, the portion of the tumor with the highest accumulation was selected as the region of interest (ROI), tumor-versus-normal ratio (TN) was defined as the ratio of average radioisotope counts per pixel in the tumor (T), divided by average counts per pixel in normal gray matter (N). The standardized uptake value (SUV) was calculated over the same tumor ROI. Met-PET scan accuracy was evaluated by correlating findings with subsequent histological analysis (8 cases) or, in cases without surgery or biopsy, by the subsequent clinical course and MR findings (3 cases).ResultsHistological examinations in 8 cases showed viable glioma cells with necrosis in 6 cases, and necrosis without viable tumor cells in 2 cases. Three other cases were considered to have radiation necrosis because they exhibited stable neurological symptoms with no sign of massive enlargement of the lesion on follow-up MR after 5 months. Mean TN was 1.31 in the radiation necrosis group (5 cases) and 1.87 in the tumor recurrence group (6 cases). Mean SUV was 1.81 in the necrosis group and 2.44 in the recurrence group. There were no statistically significant differences between the recurrence and necrosis groups in TN or SUV. Furthermore, we made a 2 x 2 factorial cross table (accumulation or no accumulation, recurrence or necrosis). From this result, the Met-PET sensitivity, specificity, and accuracy in detecting tumor recurrence were determined to be 100%, 60%, and 82% respectively. In a false positive-case, glial fibrillary acidic protein (GFAP) immunostaining showed a positive finding.ConclusionThere were no significant differences between recurrent malignant glioma and radiation necrosis following SRS in Met-PET. However, this study shows Met-PET has a sensitivity and accuracy for differentiating between recurrent glioma and necrosis, and presents important information for developing treatment strategies against post radiation reactions.

Evaluation of treatment effects in brain abscess with positron emission tomography: comparison of fluorine-18-fluorodeoxyglucose and carbon-11-methionine.

Positron emission tomography (PET) imaging is in common use preoperatively to clinically evaluate patients who present with central nervous system mass lesions. The usefulness of PET is also recognized as a method to detect intracranial tumorous lesions. A number of papers report that some inflammatory processes also showed the uptake of Fluorine-18-Fluorodeoxyglucose (FDG) and Carbon-11-Methionine (Met) tracers. We performed two PET studies before and after treatment in 4 patients with brain abscess. PET showed the uptake of both tracers to the brain abscess before treatment. The area showing an increased uptake of Met corresponded closely to the enhanced area on both CT and MR images. FDG-PET visually showed an uptake of FDG in a small area corresponding to an enhanced lesion within the CT and MR images. After treatment the area of lesions became small on enhancement CT or MRI and both PET studies showed reduced lesion and decreased uptake. The mechanism of Met uptake in the inflammatory area may be related to the higher metabolic rate and the active transport of amino acids as well as disruption of the blood brain barrier. Furthermore, it appears that the mechanism of FDG uptake is also related to a higher metabolic rate and, in addition, is related to the increased density of inflammatory cells. PET studies, more directly, reflect the degree of inflammatory response in brain abscess than enhancement CT or MRI. Therefore, PET is useful in detecting the inflammatory lesion and assessing the clinical effects of antibiotics treatment on brain abscesses.

Transfemoral, Transvenous Embolisation of Dural Arteriovenous Fistula Involving the Isolated Transverse-Sigmoid Sinus from the Contralateral Side

Summary. Background: A dural arteriovenous fistula (AVF) involving the transverse-sigmoid (T-S) sinus which is occluded at its proximal and distal ends i.e., an isolated sinus, runs the risk of haemorrhaging or causing serious neurological deficits as a result of its retrograde leptomeningeal venous drainage. While lesions of this type have not been considered to be treatable by percutaneous, transvenous embolisation, this paper challenges this view. Case Presentation: Two middle-aged men with dural AVFs involving the isolated left T-S sinus presented with motor aphasia due to focal brain edema or haemorrhage. Under local anaesthesia, transfemoral, transvenous embolisation was performed with a microcatheter that was passed through the occluded proximal transverse sinus from the right (contralateral) side. The isolated sinus was then occluded with platinum coils. This embolisation resulted in angiographic and clinical cure of dural AVFs in both patients. Interpretation: Transfemoral, transvenous embolisation is a therapeutic alternative for the treatment of dural AVFs involving the isolated T-S sinus. Embolisation obviates the need for craniotomy and general anaesthesia, which are required for the established modes of treatment, i.e., direct surgery or direct percutaneous sinus packing.

Lateral situated sinus pericranii. case report

We hereby report a case of a laterally situated sinus pericranii, which is rare. According to the articles regarding this kind of lesion, carotid angiograms revealed no pathological findings, and venograms taken with direct injection of contrast medium into the mass were useful. It should be stressed that the lesion could be demonstrated in the late phase of carotid angiograms, and digital subtraction angiography was especially useful for diagnosis. The literature is also reviewed.

Glucocorticoid treatment of brain tumor patients: changes of apparent diffusion coefficient values measured by MR diffusion imaging

Glucocorticoids (GCC) generally are administered to patients with brain tumors to relieve neurological symptoms by decreasing the water content in a peritumoral zone of edema. We hypothesized that diffusion imaging and apparent diffusion coefficient (ADC) values could detect subtle changes of water content in brain tumors and in peritumoral edema after GCC therapy. The study consisted of 13 patients with intra-axial brain tumor, and ADC was measured in the tumor, within peritumoral edema, and in normal white matter remote from the tumor before and after GCC therapy. ADC also was measured in normal white matter in four control patients with no intracranial disease who were treated with GCC for other indications. Conventional MR images showed no visually evident interval change in tumor size or the extent of peritumoral edema in any subject after GCC therapy, which nonetheless resulted in a decrease in mean ADC of 7.0% in tumors (P<0.05), 1.8% in peritumoral edema (P>0.05, not significant) and 5.8% in normal white matter (P<0.05). In patients with no intracranial disease, GCC therapy decreased mean ADC in white matter by 5.4% (P<0.05). ADC measurement can demonstrate subtle changes in the brain after GCC therapy that cannot be observed by conventional MR imaging. Measurement of ADC proved to be a sensitive means of assessing the effect of GCC therapy, even in the absence of visually discernible changes in conventional MR images.

Usefulness of interventional embolization of the middle meningeal artery for recurrent chronic subdural hematoma: Five cases and a review of the literature

Purpose Although several strategies against recurrent chronic subdural hematoma (CSDH) have been proposed, no consensus has been established. Recently, middle meningeal artery (MMA) embolization has been proposed as radical treatment for recurrent CSDH. We wanted to estimate the usefulness of MMA embolization for recurrent CSDH. Methods From February 2012 to June 2013, 110 patients with CSDH underwent single burr-hole surgery with irrigation and drainage. Among these patients, 13 showed recurrent hematoma formation and were retreated surgically. Furthermore, repeated recurrence of CSDH was observed in six patients. Five of these six patients underwent middle meningeal artery (MMA) embolization with polyvinyl alcohol particles. All five patients with interventional treatment were observed for four to 60 weeks. Results No more recurrence of CSDH was observed in any of the patients. During the follow-up period, no patients suffered from any side effects or complications from the interventional treatment. Conclusion MMA embolization with careful attention paid to the procedure might be a treatment of choice for recurrent CSDH.

Microsurgical interruption of dural arteriovenous fistula at the foramen magnum

We report two rare cases of progressive congestive myelopathy caused by dural arteriovenous fistulae (DAVF) at the foramen magnum. The first, a 69-year-old male with a 2-year history of progressive myelopathy, had symptoms unrecognized due to a past history that included spinal caries and congenital dislocation of the hip. The second, a 60-year-old male, had a recurrence of the myelopathy three months after endovascular occlusion of the DAVF feeding artery. Both patients were successfully treated by direct microsurgical interruption of the arterialized medullary vein with functional and radiological improvement. The clinical manifestations of DAVF at the foramen magnum are nonspecific, mimicking those of cervical spondylotic myelopathy or cervical neoplasm. Accurate and early diagnosis followed by complete obliteration of the fistula is mandatory to avoid permanent neurological deficit.

Atypical spinal dural arteriovenous fistula with supply from the lateral sacral artery

We report a dural arteriovenous fistula (AVF) that developed at a site on the midline dorsal surface of the dura mater that had been damaged by repeated lumbar punctures. A 61-year-old male patient had undergone repeated lumbar punctures and discectomy for severe lumbago 40 years before the present admission. After surgery, the lumbago symptoms resolved. However, 30 years after the operation, he started to experience dysaesthesia, motor weakness in both legs, and urinary disturbance. Physical examination revealed bilateral leg weakness, diminished deep tendon reflexes in the patellar and Achilles tendons bilaterally, and decreased superficial sensation below L1. Magnetic resonance imaging revealed swelling with intramedullary high intensity and multiple flow voids around the conus and spinal cord on T(2)-weighted images, and adhesive arachnoiditis. Spinal angiography revealed an AVF between the left lateral sacral artery and the S1 radicular vein at the site of the previous operation. Surgery was conducted to carry out excision of the dural AVF at the shunting point, the arterialized intradural vein, and lysis of the arachnoiditis. This case of dural AVF may have been caused by repeated lumbar punctures.

Post-embolisation susceptibility changes in giant meningiomas: multiparametric histogram analysis using non-contrast-enhanced susceptibility-weighted PRESTO, diffusion-weighted and perfusion-weighted imaging

PurposeTo investigate imaging characteristics of post-embolised meningioma and to determine if SW imaging can delineate tumour ischaemia.Materials and methodsSixteen patients were studied before and after preoperative embolisation therapy (8 histopathologically determined with ischaemia, 8 with non-ischaemia). In each patient, a slice-wise ROI for the entire tumour was established, and histogram variables (mean, SD, minimum, maximum, histogram width, mode, and peak height) of SW, ADC, CBV, CBF, MTT, and TTP maps were compared between ischaemic and non-ischaemic groups. Changes in SW histogram were correlated with histopathological characteristics.ResultsSignal intensity on the SW map tended to decrease in the ischaemic group and partially increased in the non-ischaemic group. A similar trend was observed on the ADC map. The PW histogram showed an MTT increase in ischaemic group; however, CBV did not show significant changes between ischaemic and non-ischaemic groups. Microhaemorrhage was slightly correlated with Δpeak height in the SW histogram.ConclusionPost-embolisation changes of intrinsic T2*-weighted MR contrasts on SW map are most likely associated with alterations in deoxyhaemoglobin levels and arterial blood flow.Key Points•Endovascular embolisation is now accepted as an adjuvant therapy for intracranial meningioma.•Magnetic resonance imaging is used to assess the effects of embolisation.•Unenhanced susceptibility-weighted MRI can delineate ischaemic and non-ischaemic areas.•Signal changes at SW imaging are associated with diffusion and perfusion abnormalities.•Three-dimensional high-resolution SW imaging offers a new imaging biomarker in assessing ischaemia.

Endovascular treatment of posterior cerebral aneurysm associated with moyamoya disease

PURPOSE A patient with moyamoya disease associated with a ruptured posterior cerebral artery aneurysm treated by endovascular embolization is presented. CASE REPORT A 47-year-old woman was admitted with severe headache to our hospital. Computed tomography demonstrated subarachnoid haemorrhage. Cerebral angiography revealed evidence of moyamoya disease and a saccular aneurysm at the P1 segment of the left posterior cerebral artery. CONCLUSION Endovascular embolization was performed using Guglielmi detachable coil (GDC), and the aneurysm was completely occluded with preservation of the parent artery. Endovascular treatment using GDC seems comparatively safe and effective for the treatment of cerebral saccular aneurysms in patients with moyamoya disease.