José María Millán

The Added Value of Apparent Diffusion Coefficient to Cerebral Blood Volume in the Preoperative Grading of Diffuse Gliomas

Is it worth doing both DWI and perfusion imaging in gliomas? These authors sought to study if ADC and rCBV improved diagnostic accuracy in the preoperative grading of gliomas by assessing 162 patients who later underwent surgery. rCBV was significantly different between grade II and IV and between grade III and IV gliomas, but not between grades II and III. ADC values were significantly different for all 3 grades. Conclusion: ADC measurements were better than rCBV values for distinguishing the grades of gliomas, and the combination of minimum ADC and maximum rCBV improved the diagnostic accuracy of glioma grading. BACKGROUND AND PURPOSE: In cerebral gliomas, rCBV correlates with tumor grade and histologic findings of vascular proliferation. Moreover, ADC assesses water diffusivity and is inversely correlated with tumor grade. In the present work, we have studied whether combined rCBV and ADC values improve the diagnostic accuracy of MR imaging in the preoperative grading of gliomas. MATERIALS AND METHODS: One hundred sixty-two patients with histopathologically confirmed diffuse gliomas underwent DWI and DSC. Mean rCBV and ADC values were compared among the tumor groups with the Student t test or ANOVA. ROC analysis was used to determine rCBV and ADC threshold values for glioma grading. RESULTS: rCBV had significantly different values between grade II and IV gliomas and between grade III and IV tumors, but there were no significant differences between grade II and III gliomas (P > .05). Grade II and III tumors also did not differ when astrocytomas, oligodendrogliomas, and oligoastrocytomas were considered separately. ADC values were significantly different for all 3 grades. The ADC threshold value of 1.185 × 10−3 mm2/s and the rCBV cutoff value of 1.74 could be used with high sensitivity in the characterization of high-grade gliomas. The area under the ROC curve for the maximum rCBV and minimum ADC was 0.72 and 0.75, respectively. The combination of rCBV and ADC values increased the area under the ROC curve to 0.83. CONCLUSIONS: ADC measurements are better than rCBV values for distinguishing the grades of gliomas. The combination of minimum ADC and maximum rCBV improves the diagnostic accuracy of glioma grading.

Severe Traumatic Head Injury: Prognostic Value of Brain Stem Injuries Detected at MRI

Because traumatic brain stem injuries are thought to imply a poor prognosis, these authors studied 188 patients with TBI and correlated their imaging findings with outcomes at 6 months. Brain stem lesions were found in 51 instances and 66% of these patients had a poor outcome, with those who had bilateral, posteriorly located, and hemorrhagic lesions having the worst outcome. Nonhemorrhagic brain stem lesions had the best outcome in this group of patients. BACKGROUND AND PURPOSE: Traumatic brain injuries represent an important cause of death for young people. The main objectives of this work are to correlate brain stem injuries detected at MR imaging with outcome at 6 months in patients with severe TBI, and to determine which MR imaging findings could be related to a worse prognosis. MATERIALS AND METHODS: One hundred and eight patients with severe TBI were studied by MR imaging in the first 30 days after trauma. Brain stem injury was categorized as anterior or posterior, hemorrhagic or nonhemorrhagic, and unilateral or bilateral. Outcome measures were GOSE and Barthel Index 6 months postinjury. The relationship between MR imaging findings of brain stem injuries, outcome, and disability was explored by univariate analysis. Prognostic capability of MR imaging findings was also explored by calculation of sensitivity, specificity, and area under the ROC curve for poor and good outcome. RESULTS: Brain stem lesions were detected in 51 patients, of whom 66% showed a poor outcome, as expressed by the GOSE scale. Bilateral involvement was strongly associated with poor outcome (P < .05). Posterior location showed the best discriminatory capability in terms of outcome (OR 6.8, P < .05) and disability (OR 4.8, P < .01). The addition of nonhemorrhagic and anterior lesions or unilateral injuries showed the highest odds and best discriminatory capacity for good outcome. CONCLUSIONS: The prognosis worsens in direct relationship to the extent of traumatic injury. Posterior and bilateral brain stem injuries detected at MR imaging are poor prognostic signs. Nonhemorrhagic injuries showed the highest positive predictive value for good outcome.

A Prognostic Model Based on Preoperative MRI Predicts Overall Survival in Patients with Diffuse Gliomas

BACKGROUND AND PURPOSE: Diffuse gliomas are classified as grades II–IV on the basis of histologic features, with prognosis determined mainly by clinical factors and histologic grade supported by molecular markers. Our aim was to evaluate, in patients with diffuse gliomas, the relationship of relative CBV and ADC values to overall survival. In addition, we also propose a prognostic model based on preoperative MR imaging findings that predicts survival independent of histopathology. MATERIALS AND METHODS: We conducted a retrospective analysis of the preoperative diffusion and perfusion MR imaging in 126 histologically confirmed diffuse gliomas. Median relative CBV and ADC values were selected for quantitative analysis. Survival univariate analysis was made by constructing survival curves by using the Kaplan-Meier method and comparing subgroups by log-rank probability tests. A Cox regression model was made for multivariate analysis. RESULTS: The study included 126 diffuse gliomas (median follow-up of 14.5 months). ADC and relative CBV values had a significant influence on overall survival. Median overall survival for patients with ADC < 0.799 × 10−3 mm2/s was <1 year. Multivariate analysis revealed that patient age, relative CBV, and ADC values were associated with survival independent of pathology. The preoperative model provides greater ability to predict survival than that obtained by histologic grade alone. CONCLUSIONS: ADC values had a better correlation with overall survival than relative CBV values. A preoperative prognostic model based on patient age, relative CBV, and ADC values predicted overall survival of patients with diffuse gliomas independent of pathology. This preoperative model provides a more accurate predictor of survival than histologic grade alone.

Acute perfusion changes after spontaneous SAH: a perfusion CT study.

BackgroundPerfusion computed tomography (CT) is a rapid technique that allows the measurement of acute disturbances in local and global cerebral blood flow in patients suffering stroke and spontaneous subarachnoid haemorrhage (SAH). The purpose of this study was to establish the relationship between different measures of brain perfusion made on dynamic-contrast CT reconstructions performed as soon as SAH has been diagnosed and the severity of the bleeding determined by the clinical grade, the extent of the bleeding and the outcome of the patients.MethodsAfter the diagnosis of SAH by conventional CT, a perfusion CT was performed before CT angiography. All imaging studies were performed on a six-slice spiral CT scanner. All images were analysed using perfusion software developed by Philips, which produces perfusion CT quantitative data based on temporal changes in signal intensity during the first pass of a bolus of an iodinated contrast agent. Measurements of mean transient time (MTT), time to peak (TTP), cerebral blood volume (CBV) and cerebral blood flow (CBF) in volumes of interest corresponding to territories perfused by the major cerebral arteries were performed. Different data regarding severity of the bleeding—such as level of consciousness, amount of bleeding in conventional CT—were collected. All poor-grade patients received a ventriculostomy catheter so that ICP recordings were obtained. Also, the occurrence of delayed cerebral ischaemia (DCI) was recorded. Outcome was assessed by the Glasgow Outcome Scale 6 months after the bleeding. For statistical analysis, non-parametric correlations between variables were performed.FindingsThirty-nine patients have been included in the study since January 2007. In SAH patients there are increasing perfusion abnormalities as the severity of the bleeding increases. The most affected perfusion parameters are TTP and MTT, as they significantly increase with the clinical severity of the bleeding and the total volume of bleeding (P < 0.01, Spearman’s Rho). When average MTT time is increased over 5.9 s there is a 20-fold (95% CI = 2.1-182) risk of poor outcome. All patients presenting this MTT time suffered from DCI. This value has a positive predictive value of 100% for DCI and 90% for a poor outcome.ConclusionsSAH causes cerebral blood flow abnormalities even in the acute phase of the illness, consisting mainly of an increase in circulation times (TTP and MTT), which are correlated with the severity of the bleeding.

Arachnoiditis ossificans:Diagnosis with helical computed tomography

Arachnoiditis ossificans (AO) is a rare entity in which ossification of the leptomeninges occurs. This report illustrates a patient with AO of the cervical and dorsal spine, diagnosed by helical computed tomography with multiplanar reconstruction. It demonstrates the value of computed tomography in diagnosing calcified plaques and the utility of multiplanar reconstruction in giving an exact anatomic reference to neurosurgeon.

Perfusion Computed Tomography in a Dural Arteriovenous Fistula Presenting With Focal Signs: Vascular Congestion as a Cause of Reversible Neurologic Dysfunction

OBJECTIVETo describe the use of perfusion computed tomography (PCT) in the study of hemodynamic disturbances associated with a case of a cerebral dural arteriovenous fistula (DAVF) with leptomeningeal venous drainage presenting with focal signs. CLINICAL PRESENTATIONA 79-year-old man presented because of loss of strength in the right arm. On examination, he presented mild right-side hemiparesis. Magnetic resonance imaging showed the presence of a left frontoparietal hyperintense lesion on T2-weighted images. Magnetic resonance angiography and digital substraction angiography (DSA) showed a convexity Borden type III DAVF. The DAVF was embolized with bucrylate, and control DSA showed complete obliteration of the malformation. The patient improved from his clinical presentation and 6 months after treatment was asymptomatic. TECHNIQUEPerfusion computed tomography was performed before and after treatment. All imaging studies were performed on a 6-slice spiral computed tomography scanner. Each series studied a 2.4-cm slide of brain at the level of the cerebral convexity where the DAVF was located. Quantitative perfusion data were obtained from significant regions of interest of both hemispheres, and an interhemispheric ratio (IR) was calculated. Pretreatment PCT showed an increase in mean transient time (IR = 2.2) and time to peak (IR = 1.15), with an increase in cerebral blood volume (IR = 1.9) in the left frontal areas related to a similar area in the contralateral hemisphere. Six months after treatment, perfusion maps did not show any interhemispheric difference. CONCLUSIONPerfusion computed tomography could help to identify the hemodynamic disturbances associated with DAVFs with leptomeningeal venous drainage.

The Effect of Cranioplasty on Cerebral Hemodynamics as Measured by Perfusion Computed Tomography and Doppler Ultrasonography

Cranioplasties are performed to protect the brain and correct cosmetic defects, but there is growing evidence that this procedure may result in neurological improvement. We prospectively studied cranioplasties performed at our hospital over a 5-year period. The National Institute of Health Stroke Scale and Barthel index were recorded prior to and within 72 h after the cranioplasty. A perfusion computed tomography (PCT) and transcranial Doppler sonography (TCDS) were performed prior to and 72 h after the surgery. For the PCT, regions irrigated by the anterior cerebral artery, the middle cerebral artery (MCA), the posterior cerebral artery, and the basal ganglia were selected, as well as the mean values for the hemisphere. The sonography was performed in the sitting and the supine position for the MCA and internal carotid. The velocities, pulsatility index, resistance index, and Lindegaard ratio (LR) were obtained, as well as a variation value for the LR (ΔLR = LR sitting - LR supine). Fifty-four patients were included in the study. Of these, 23 (42.6%) patients presented with objective improvement. The mean cerebral blood flow of the defective side (m-CBF-d) increased from 101.86 to 117.17 mL/100 g/min (p = 0.064), and the m-CBF of the healthy side (m-CBF-h) increased from 128.14 to 145.73 mL/100 g/min (p = 0.028). With regard to the TCDS, the ΔLR was greater on the defective side prior the surgery in those patients who showed improvement (1.295 vs. -0.714; p = 0.002). Cranioplasty resulted in clinical improvement in 40% of the patients, with an increase in the post-surgical CBF. The larger variations in the LR when the patient is moved from the sitting to the supine position might predict the clinical improvement.

Brainstem stroke: anatomy, clinical and radiological findings.

Ischemic brainstem strokes constitute 10% of all ischemic brain strokes. Hemorrhagic complications are associated with an especially poor prognosis. Associated symptomatology includes vertigo, cranial nerve symptoms, and crossed or uncrossed corticospinal tract findings. Advanced neuroimaging techniques have become essential in the decision-making process of brainstem stroke management and may provide a means to identify those patients who may benefit from thrombolysis. Because many of the recommendations are based on limited data, additional research on treatment of acute brainstem stroke is needed.

Parosteal osteosarcoma of the skull.

Parosteal osteosarcoma of the skull is a distinct surface bone tumor, with a better prognosis than conventional osteosarcoma. The most common location is on the surface of the distal femur which accounts for 46-66% of the cases. The presentation in the skull is uncommon and there are few cases reported in the literature. We describe the case of a man who developed a parosteal osteosarcoma arising from the occipital bone with extension to the parietal bone. The patient was operated and had a complete tumor resection.