P. Nakstad

Cerebral Vasospasm After Subarachnoid Haemorrhage Investigated by Means of Transcranial Doppler Ultrasound

Measurements of flow velocity in defined segments of the basal cerebral arteries can be obtained through the intact adult skull using 2 MHz pulsed Doppler ultrasound. We compared flow velocity in these vessels with findings from 56 cerebral angiographies obtained in 51 patients at from day 1 to day 21 after subarachnoid haemorrhage (SAH). The diameter of the proximal segment of the middle cerebral, anterior cerebral, and posterior cerebral arteries (MCA, ACA, and PCA, respectively) were measured from anteroposterior films produced in one angiographic laboratory. In patients investigated on day 1-2, the median MCA diameter was 2.8 mm with range 2.3-3.4 mm. The median flow velocity was 56 cm/s, range 36-88 cm/s (within normal limits). There was a clear inverse relationship between the MCA diameter and MCA flow velocity. Eleven of the 13 MCAs having diameter 1.5 mm or less showed flow velocity in excess of 140 cm/s. This seems a useful limit to diagnose pronounced MCA spasm (50% diameter reduction) with this method. Further clues to the severity of MCA spasm were obtained from the ratio calculated dividing the MCA flow velocity by the flow velocity in the ipsilateral, extracranial internal carotid artery (ICA), since spasm probably does not involve the neck vessels. This ratio was from 1.1 to 2.3, median 1.7 at day 1-2, but rose to over 10 in patients with the most severe MCA lumen narrowing. The PCA flow velocity was inversely related to the PCA diameter. Assessment of ACA spasm requires considering findings from both hemispheres combined, since the two proximal ACAs usually anastomose through the anterior communicating artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative Apparent Diffusion Coefficients in the Characterization of Brain Tumors and Associated Peritumoral Edema

Background: Conventional magnetic resonance (MR) imaging has a number of limitations in the diagnosis of the most common intracranial brain tumors, including tumor specification and the detection of tumoral infiltration in regions of peritumoral edema. Purpose: To prospectively assess if diffusion-weighted MR imaging (DWI) could be used to differentiate between different types of brain tumors and to distinguish between peritumoral infiltration in high-grade gliomas, lymphomas, and pure vasogenic edema in metastases and meningiomas. Material and Methods: MR imaging and DWI was performed on 93 patients with newly diagnosed brain tumors: 59 patients had histologically verified high-grade gliomas (37 glioblastomas multiforme, 22 anaplastic astrocytomas), 23 patients had metastatic brain tumors, five patients had primary cerebral lymphomas, and six patients had meningiomas. Apparent diffusion coefficient (ADC) values of tumor (enhancing regions or the solid portion of tumor) and peritumoral edema, and ADC ratios (ADC of tumor or peritumoral edema to ADC of contralateral white matter, ADC of tumor to ADC of peritumoral edema) were compared with the histologic diagnosis. ADC values and ratios of high-grade gliomas, primary cerebral lymphomas, metastases, and meningiomas were compared by using ANOVA and multiple comparisons. Optimal thresholds of ADC values and ADC ratios for distinguishing high-grade gliomas from metastases were determined by receiver operating characteristic (ROC) curve analysis. Results: Statistically significant differences were found for minimum and mean of ADC tumor and ADC tumor ratio values between metastases and high-grade gliomas when including only one factor at a time. Including a combination of in total four parameters (mean ADC tumor, and minimum, maximum and mean ADC tumor ratio) resulted in sensitivity, specificity, positive (PPV), and negative predictive values (NPV) of 72.9, 82.6, 91.5, and 54.3% respectively. In the ROC curve analysis, the area under the curve of the combined four parameters was the largest (0.84), indicating a good test. Conclusion: Our results suggest that ADC values and ADC ratios (minimum and mean of ADC tumor and ADC tumor ratio) may be helpful in the differentiation of metastases from high-grade gliomas. It cannot distinguish high-grade gliomas from lymphomas, and lymphomas from metastases. ADC values and ADC ratios in peritumoral edema cannot be used to differentiate edema with infiltration of tumor cells from vasogenic edema when measurements for high-grade gliomas, lymphomas, metastases, and meningiomas were compared.

Embolization of intracranial arteriovenous malformations and fistulas with polyvinyl alcohol particles and platinum fibre coils

SummaryIn order to reduce the recanalization rate of arteriovenous malformations and multiple dural arteriovenous fistulas, embolization was carried out with polyvinyl alcohol (PVA) particles combined with platinum fibre coils in 20 patients. The malformation was occluded more effectively than by PVA alone. Distal deposition of the emboli was obtained by improved steerable catheters (Tracker-18-unibody) and guidewires. The complication rate was lower than usually reported from studies using glue as embolic agent. It was concluded that the combination of PVA and fibre coils enhances the safety and effectiveness of embolization therapy and reduces the frequency of recanalization of intracranial AVMs.

MR angiography in the follow-up of coiled cerebral aneurysms after treatment with guglielmi detachable coils

Purpose: Intra-arterial digital subtraction angiography (DSA) has been considered the gold standard examination in the follow-up of patients treated with Guglielmi detachable coils (GDCs). However, DSA is an invasive and expensive investigation and results in exposure to ionising radiation to both patient and operator. The aim of this study was to compare MR angiography (MRA) with DSA with regard to patency of the occlusion of aneurysms following GDC treatment. Material and Methods: We performed 75 MRA and DSA examinations on 51 patients treated with GDCs. The examinations were performed 3-36 months after embolisation and the interval between MRA and DSA was less than 1 week. Hard copies of both studies were interpreted retrospectively and independently for residual flow within the aneurysm, residual aneurysmal neck, and parent and branch vessel flow. Results: Patency status of parent and branch vessel flow was correctly identified with MRA in all patients except 1. The sensitivity of MRA in revealing residual flow within the aneurysm was 97%. The specificity in ruling out residual flow within the aneurysm was 91%. Conclusion: MRA may replace DSA in the long-term follow-up of coiled cerebral aneurysms. The initial follow-up examination should, however, include both modalities.

Multiple spinal arteriovenous fistulas in Klippel-Trenaunay-Weber syndrome treated with platinum fibre coils

SummaryA 13-year-old girl with Klippel-Trenaunay-Weber syndrome and intradural extramedullary spinal arteriovenous fistulas is presented. Pre-embolization balloon test occlusions and embolization with platinum fibre coils were carried out in three sessions, after which the myelopathy and the intense back pain disappeared. Our conclusion is that spinal fistulas can be safely and effectively treated with fibre coils in combination with balloon testing.

Superselective angiography, embolisation and surgery in treatment of arteriovenous malformations of the brain.

We prospectively evaluated a diagnostic and therapeutic procedure combining superselective, angiography, endovascular embolisation and surgery in arteriovenous malformations (AVM) of the brain. Our aim was to achieve the best possible result exposing the patients to the lowest possible risk. During a 3 year period 48 patients were studied, of whom 22 (46%) were treated by incomplete preoperative embolisation and subsequent complete surgical removal of the AVM. All angiography and embolisations were performed with the Tracker catheter system using polyvinyl alcohol particles and/or platinum fibre coils. The other 26 patients were treated as follows: incomplete embolisation in 11 (23%), complete embolisation in 2 (4%), angiography and surgery in 3 (6%) and combined embolisation and radiation in 7 (15%), 3 patients were excluded from any therapy after superselective angiography. The total number of acute complications and permanent sequelae were 8 (17%) and 3 (6%) respectively. We concluded that superselective cerebral angiography, a relatively safe procedure, should play an impotant role in deciding treatment strategies for AVMs of the brain. The risks of combined embolisation and surgery are probably lower than those of either alone. In a few cases surgery or embolisation alone carries an unequivocally lower risk, and combined therapy is not justifiable.

Measurements of diagnostic examination performance and correlation analysis using microvascular leakage, cerebral blood volume, and blood flow derived from 3T dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging in glial tumor grading

IntroductionTo assess the diagnostic accuracy of microvascular leakage (MVL), cerebral blood volume (CBV) and blood flow (CBF) values derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC-MR imaging) for grading of cerebral glial tumors, and to estimate the correlation between vascular permeability/perfusion parameters and tumor grades.MethodsA prospective study of 79 patients with cerebral glial tumors underwent DSC-MR imaging. Normalized relative CBV (rCBV) and relative CBF (rCBF) from tumoral (rCBVt and rCBFt), peri-enhancing region (rCBVe and rCBFe), and the value in the tumor divided by the value in the peri-enhancing region (rCBVt/e and rCBFt/e), as well as MVL, expressed as the leakage coefficient K2 were calculated. Hemodynamic variables and tumor grades were analyzed statistically and with Pearson correlations. Receiver operating characteristic (ROC) curve analyses were also performed for each of the variables.ResultsThe differences in rCBVt and the maximum MVL (MVLmax) values were statistically significant among all tumor grades. Correlation analysis using Pearson was as follows: rCBVt and tumor grade, r = 0.774; rCBFt and tumor grade, r = 0.417; MVLmax and tumor grade, r = 0.559; MVLmax and rCBVt, r = 0.440; MVLmax and rCBFt, r = 0.192; and rCBVt and rCBFt, r = 0.605. According to ROC analyses for distinguishing tumor grade, rCBVt showed the largest areas under ROC curve (AUC), except for grade III from IV.ConclusionBoth rCBVt and MVLmax showed good discriminative power in distinguishing all tumor grades. rCBVt correlated strongly with tumor grade; the correlation between MVLmax and tumor grade was moderate.

No altered dorsal anterior cingulate activation in bipolar II disorder patients during a Go/No-go task: an fMRI study.

OBJECTIVES It has been reported that one of the core features in patients with bipolar disorder II (BD II) is increased impulsivity. The aim of this study was to investigate whether patients with BD II showed decreased activation in the dorsal anterior cingulate cortex (dACC) as compared to healthy controls when performing a task sensitive to impulsivity. METHODS Twenty-seven BD II patients and 28 healthy controls performed a Go/No-go task during a functional magnetic resonance imaging (fMRI) session. Eleven of the patients were unmedicated, and possible group differences between medicated and unmedicated patients were also assessed. RESULTS The groups did not differ in behavioral performance on the Go/No-go task. Both BD II subjects and healthy controls demonstrated dACC activity during the task, and analyses revealed no statistically significant group differences. Medicated and unmedicated patients also did not differ in the degree of fMRI activation. CONCLUSIONS These findings do not support the hypothesis of abnormal dACC activity during a Go/No-go task in BD II patients.

Cervical myelography with iohexol

SummaryAn open study with iohexol (Omnipaque) in cervical myelography has been performed in 20 patients to evaluate the properties and neurotoxicity of this new water soluble contrast medium. The image quality was good (30%) or excellent (70%) in all cases. The frequency of headache was 25%. No EEG changes were severe and the total frequency was 20%. We conclude that this study supports other reports of iohexol having a low neurotoxicity and is well suited for intrathecal use.

Haemodynamic aspects of clinical cerebral angiography concurrent two vessel monitoring using transcranial Doppler ultrasound

SummaryTo overcome the technical limitations which have precluded noninvasive Doppler ultrasound in investigation of rapid cerebral haemodynamic responses in two cerebrovascular beds at the same time, we have modified a commercial 2 MHz pulsed Doppler instrument with online spectrum analysis. Two probes are activated intermittently, recording eight averaged Doppler-shifted spectra from each probe sequentially.Concurrent recordings of blood velocity in both middle cerebral arteries were performed during 25 selective iohexol carotid angiography runs in 13 patients with near normal cerebral vasculature. The technique permitted the differentiation between the specific responses confined to the recipient vascular bed, and the general responses occurring in remote brain areas as well. The specific response to iohexol was biphasic; a significant decrease in blood velocity occurred <4 s after the bolus entry, probably due to the high viscocity of iohexol. Between 4 and 12s, blood velocity was significantly increased, reflecting the cerebrovascular response to hypertonic solutions. The blood velocity on the opposite side increased from <4 s through 45 s after iohexol. This concurs with studies using electromagnetic flowmetry, and suggests that these general responses are elicited by anxiety, discomfort and pain. Thus, no general responses were seen during angiography under general anaesthesia.Eight patients investigated during catheter flushing with normal saline showed a biphasic specific response reciprocal to that due to iohexol. A significant blood velocity peak occurred < 4 s after the bolus entry, followed by a decrease between 4 and 60 s. The saline injections produced no pain and evoked no significant general response.