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.

The human amygdala is involved in general behavioral relevance detection: evidence from an event-related functional magnetic resonance imaging Go-NoGo task.

The amygdala is classically regarded as a detector of potential threat and as a critical component of the neural circuitry mediating conditioned fear responses. However, it has been reported that the human amygdala responds to multiple expressions of emotions as well as emotionally neutral stimuli of a novel, uncertain or ambiguous nature. Thus, it has been proposed that the function of the amygdala may be of a more general art, i.e. as a detector of behaviorally relevant stimuli [Sander D, Grafman J, Zalla T (2003) The human amygdala: an evolved system for relevance detection. Rev Neurosci 14:303-316]. To investigate this putative function of the amygdala, we used event related functional magnetic resonance imaging (fMRI) and a modified Go-NoGo task composed of behaviorally relevant and irrelevant letter and number stimuli. Analyses revealed bilateral amygdala activation in response to letter stimuli that were behaviorally relevant as compared with letters with less behavioral relevance. Similar results were obtained for relatively infrequent NoGo relevant stimuli as compared with more frequent Go stimuli. Our findings support a role for the human amygdala in general detection of behaviorally relevant stimuli.

Fluoroscopy-guided sacroplasty: special focus on preoperative planning from three-dimensional computed tomography.

BACKGROUND: Osteoporotic sacral insufficiency fractures are usually spontaneous or caused by discrete traumas. The fluoroscopic anatomy of the sacrum can be difficult to understand, and this is why sacroplasty is considered more challenging than ordinary vertebroplasties. PURPOSE: To demonstrate the planning of the procedure and the effectiveness of treatment with sacroplasty by means of three-dimensional computed tomography (3D CT) by combining multiplanar reconstructions (MPR) and volume-rendering technique (VRT). MATERIAL AND METHODS: Five elderly, osteoporotic patients with intense pelvic and hip pain underwent weeks of inconclusive clinical and radiological diagnostic efforts. Correct diagnosis was finally attained with magnetic resonance imaging (MRI) and CT. Plain radiographs rarely show fractures, and MR or CT examinations are necessary to demonstrate longitudinal fractures. The procedures were performed with digital biplane equipment using preoperative 3D CT planning procedures. Polymethyl methacrylate (PMMA) was injected to fill the fracture sites. RESULTS: The fractures were successfully treated with sacroplasty using PMMA. A new technique, which involves placing the needles along the long axis of the sacrum, was optimized to the individual patients' fractures and sacral anatomy by meticulous planning on a workstation with 3D CT data sets. It was technically successful in all five cases. Four of the five patients had sustained pain relief. CONCLUSION: Sacral insufficiency fractures are not uncommon and should be considered in the elderly population with low back pain. Sacroplasty using the optimized "long-axis technique" gave almost immediate pain relief for all five patients in our study material. No complications were observed.

Bilateral arachnoid cysts of the temporal fossa in four children with glutaric aciduria type I.

Glutaric aciduria type I is an uncommon inborn error of metabolism. It is a serious disease, often with a fatal outcome. This study reports the presence of bilateral temporal fluid collections, probably bilateral arachnoid cysts, in association with glutaric aciduria type I. The CT and, when available, MR studies from five patients with this disorder were reviewed. Four of the patients had findings consistent with bilateral arachnoid cysts of the temporal fossa. This is a rare occurrence, with only 11 such cases reported in the literature. The observed association between temporal fluid collections and glutaric aciduria type I suggests that patients with bilateral arachnoid cysts should be investigated for this metabolic disorder.

Omnipaque vs. Hexabrix in intravenous DSA of the carotid arteries: randomized double-blind crossover study.

A randomized double-blind crossover study using Omnipaque 350 mg l/ml (iohexol) and Hexabrix 320 mg l/ml (ioxaglate) in 53 patients undergoing intravenous digital subtraction angiography of the carotid arteries revealed no significant differences in image quality. Some differences were found in subjective side effects that favored Omnipaque. Nausea was reported in four patients after injection of Hexabrix, and a metallic taste was significantly more frequent (p less than 0.01) with this contrast medium. The patients' preference for Omnipaque was also statistically significant (p less than 0.01). It was concluded that both contrast media are suitable for intravenous digital subtraction angiography.

Effect of Guglielmi detachable coil placement on intraaneurysmal pressure: experimental study in canines.

BACKGROUND AND PURPOSE: Treatment of ruptured aneurysms with Guglielmi detachable coils (GDCs) has been shown to prevent repeat bleeding. To assess whether GDC coiling alters aneurysmal pressure, we measured intraaneurysmal pressure in two canine types of carotid artery aneurysms before and after GDC placement. METHODS: A 0.014-inch guidewire with a pressure transducer was inserted into parent arteries and domes of surgically created aneurysms. Intravascular static pressures were recorded before and during saline power injections (10, 20, and 30 mL over 1 and 2 s), before and after GDC placement. Common femoral arterial pressure was monitored. RESULTS: Saline power injections reproducibly and abruptly increased pressure in parent arteries and aneurysms. Mean intraaneurysmal pressure varied (18 +/- 4 [10 mL] to 75 +/- 15 mm Hg [30 mL]), independent of injection duration. Intraaneurysmal baseline pressures were higher after GDC placement (111 +/- 10 versus 93 +/- 15 mm Hg; P =.05). Aneurysmal pressure increases with saline injections were slightly higher after GDC placement, which dampened intraaneurysmal pressure amplitude at baseline (26.5 +/- 5.6 versus 19.6 +/- 7.4 mm Hg; P =.003) and during hypertension (25.3 +/- 5.4 versus 19.8 +/- 7.5 mm Hg, P =.002). The pressure increase slope with saline injection was delayed with GDC placement (0.24 +/- 0.1 versus 0.38 +/- 0.19 s; P <.001). CONCLUSION: Graded saline power injections into parent arteries can rapidly increase intraaneurysmal pressure. GDC treatment did not attenuate mean intraaneurysmal pressures, but both dampened the pressure amplitude and delayed pressure increases during locally induced hypertension.

Intravenous digital subtraction angiography of the precerebral and cerebral arteries in patients with TIA. A comparison with conventional angiography.

A study of the diagnostic utility of both intravenous digital subtraction angiography (IV-DSA) and conventional angiography of precerebral and cerebral arteries is presented. The series comprised 60 patients with TIA, who underwent the two procedures with a mean interval of 16 days. Conventional angiography was generally superior to IV-DSA, and this was particularly marked in the siphons and cerebral arteries. Only the excellent IV-DSA examinations obtained in a few patients with TIA could be accepted as final pre-operative procedures. Accurate imaging of the lesions and collateral flow pattern usually required intra-arterial injections, and intra-arterial DSA is now usually preferred.

Failure to confirm neurotoxic impairment using cerebral magnetic resonance imaging on solvent-exposed workers.

OBJECTIVES: The study aimed at assessing signs of nervous system impairment by cerebral magnetic resonance imaging (MRI) among workers with a history of long-term exposure to mixtures of organic solvents. METHODS: Thirty-six workers (mean age 44.1 years) with at least 10 (mean 23.9) years of occupational exposure to solvents and pair-matched referents with no former solvent exposure went through a blind, random-order investigation of cerebral MRI, performed with a 1.5-tesla scanner. RESULTS: Linear measurements of the MRI tomograms showed a slight tendency toward wider ventricles and broader cortical sulci in the reference group. Visual evaluation of the MRI by 2 experienced neuroradiologists showed no significant difference between the groups; however, there was substantial interobserver variability. CONCLUSIONS: The MRI findings of this study do not support the hypothesis that long-term low-level occupational exposure to organic solvents results in the development of brain atrophy, or specific MRI signal changes in the region of the basal ganglia and thalami.

Motivation alters response bias and neural activation patterns in a perceptual decision-making task.

Motivation has been demonstrated to affect individuals' response strategies in economic decision-making, however, little is known about how motivation influences perceptual decision-making behavior or its related neural activity. Given the important role motivation plays in shaping our behavior, a better understanding of this relationship is needed. A block-design, continuous performance, perceptual decision-making task where participants were asked to detect a picture of an animal among distractors was used during functional magnetic resonance imaging (fMRI). The effect of positive and negative motivation on sustained activity within regions of the brain thought to underlie decision-making was examined by altering the monetary contingency associated with the task. In addition, signal detection theory was used to investigate the effect of motivation on detection sensitivity, response bias and response time. While both positive and negative motivation resulted in increased sustained activation in the ventral striatum, fusiform gyrus, left dorsolateral prefrontal cortex (DLPFC) and ventromedial prefrontal cortex, only negative motivation resulted in the adoption of a more liberal, closer to optimal response bias. This shift toward a liberal response bias correlated with increased activation in the left DLPFC, but did not result in improved task performance. The present findings suggest that motivation alters aspects of the way perceptual decisions are made. Further, this altered response behavior is reflected in a change in left DLPFC activation, a region involved in the computation of perceptual decisions.

The reaction of cerebral arteries to non-ionic contrast media during cerebral angiography.

The purpose of this study was to evaluate possible vasoconstrictive or vasodilatator effects of the low osmolar non-ionic contrast medium iohexol (Omnipaque) on the calibre of cerebral arteries. The diameters of respectively 5 and 6 different locations of the vertebral and carotid arteries were recorded from angiograms of 3 successive injections. The material consisted of 18 patients. It could not be shown that Omnipaque induced vasoconstriction or vasodilatation when normal doses and adequate technique was applied. The difference in diameters found were not statistically significant and are probably due to natural pulsations and to the difficulties in performing exact measurements.

Interventional neuroradiology.

The purpose of this article is to provide an overview of all aspects concerning interventional neuroradiology of vascular central nervous diseases. Today, interventional neuroradiology can help many patients that, even until a few years ago, did not have any possibility for a safe cure. Complex cerebral arteriovenous malformations and fistulas, inoperable aneurysms and intravascular thromboses are often treated with interventional neuroradiology alone, while in other cases a combination of neurosurgery and radiation may help in reaching a good outcome for the patients. In the past few decades the efforts by neuroradiologists and collaborating clinicians to develop treatment strategies and methods for these and other high-risk diseases represent a vast, fascinating field of modern medicine. The article therefore focusses on the state-of-the-art and describes presently used methods for diseases that can be treated with interventional neuroradiology. Literature dealing with the historical development of interventional neuroradiology and important publications of recent scientific work are reviewed, providing the reader with an overview of the most pertinent material on each disease discussed. Aspects of training and ethics are discussed and emphasis is focussed on the importance of recognizing these aspects as essential in any case of interventional radiological treatment.

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 important 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.

[Neuroradiologic intervention in intracranial arteriovenous malformations]. / Neuroradiologisk intervensjon ved intrakranielle arteriovenøse malformasjoner.

23 patients with intracranial arteriovenous malformations and durafistulas were embolized. 13 underwent embolization with polyvinylalcohol and silk threads as the only means of therapy, while six were also operated on, and four received radiation after considerable reduction of the nidus had been achieved. No death or major complications occurred in these patients. The authors considered the embolization to be successful in all cases.

Side effects and complications of automated percutaneous lumbar nucleotomy.

We reviewed the records of 243 patients treated at 271 disc levels to determine the incidence of side effects and complications of percutaneous nucleotomy. In our early experience there were 7 technical failures (2.5% of all attempts), of which 6 were at the 5th disc level. The success rate dropped from 67% at 3 months to 60% 1 year after treatment due to recurrences in 16 patients (6.6%). Extruded or sequestered fragments were found in 6 patients (2.4%), and may have been caused by nucleotomy. However, only one was accompanied by aggravation of symptoms. Discitis was seen in 2 patients (0.8%), both treated at two separate disc levels. About half the patients experienced increased low back pain, mean duration 9 days, after treatment, and 3 (1.2%), of whom 2 also had nonorganic disorders, needed admission to hospital because of severe pain. Mild spasm and a sensation of instability were noted by 9.6% and 25% of the patients respectively. Injury to nerves, bowels, vessels or ureters or a dural leak never occurred. The study confirms earlier reports that the rate of serious complications is low.

CT changes after conservative treatment for lumbar disk herniation.

In order to assess changes occurring to lumbar disk herniations and bulges and to the disk spaces after conservative treatment, a follow-up CT was carried out of 106 pathologic disks in 92 patients at a mean interval of 14 months after the initial examination. There was a strong association between the evolution of the hernias and clinical results, with a decrease in size of the majority of hernias in successfully treated patients, whereas the others essentially remained unchanged (p < 0.0001). A significantly higher proportion of large hernias diminished as compared to the smaller ones (p < 0.0001). Diffuse disk bulges were associated with a poor outcome and never regressed. There was a lower incidence of diminution of the central hernias compared to other locations. Patients with normal disk space at the initial examination had a better outcome than those with disk space narrowing. Only occasionally was a reduction of the disk space observed at follow-up.

[Neurologic magnetic resonance tomography--indications and practical use]. / Nevroradiologisk magnetisk resonanstomografi--indikasjoner og bruksområder.

Magnetic resonance tomography is considered the most important technique in modern neuroradiology. This article demonstrates the importance of MR imaging in the diagnosis of diseases of the central nervous system. Modern neuroradiology is completely dependent upon this modality, and sections and departments of neuroradiology should have great responsibility for both diagnostic MR imaging and the day-to-day operation MR laboratories.

Computed tomography in the evaluation of the supraclinoid arteries in suprasellar pituitary gland tumors.

The demonstration of the supraclinoid arteries at CT in 38 patients with suprasellar lesions was evaluated. The anterior cerebral artery was visible in 8 per cent, the other supraclinoid arteries in about 80 per cent. In one patient cerebral angiography revealed a giant aneurysm which was erroneously considered as a suprasellar neoplasm at CT and encephalography. The demonstration of the supraclinoid arteries was often inadequate in large suprasellar tumors. Therefore, cerebral angiography is still necessary preoperatively in suprasellar pituitary lesions-at least at the state of technology represented by the Delta 25 Head Scanner.

Coronal MR imaging of the normal 3rd, 4th, and 5th lumbar and 1st sacral nerve roots.

Seven healthy volunteers underwent coronal MR imaging at 1.5 tesla of the normal 3rd, 4th, and 5th lumbar, and 1st sacral nerve roots. Coronal slices, 3-mm-thick with a 0.3-mm gap between the slices were obtained (TR/TE 600/22) through the lumbar spinal canal. All the nerve roots were visible on at least one image. One can routinely expect to demonstrate the 3rd, 4th, and 5th lumbar, and 1st sacral nerve roots on T1-weighted, 3-mm-thick coronal MR scans. We found no correlation between the degree of lumbar lordosis and the lengths of the visible nerve roots. Five patients with one of the following spinal problems: anomaly, tumor, disk herniation, and failed back surgery syndrome were examined according to our protocol. In all these cases coronal MR imaging gave the correct diagnosis.

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

A 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.