A prospective comparison between three-dimensional magnetic resonance imaging and ventriculography for target-coordinate determination in frame-based functional stereotactic neurosurgery

OBJECT: The purpose of this prospective study was to compare stereotactic coordinates obtained with ventriculography with coordinates derived from stereotactic computer-reconstructed three-dimensional magnetic resonance (3D-MR) imaging in functional stereotactic procedures. METHODS: In 15 consecutive patients undergoing functional stereotactic procedures, both preoperative frame-based stereotactic 3D-MR imaging and intraoperative ventriculography were performed. Differences between 3D-MR imaging and ventriculography in X, Y, and Z coordinates of the anterior commissure (AC), posterior commissure (PC), and target area were calculated, as well as the 3D distance between the position of AC, PC, and target within stereotactic space as obtained using both methods. The position of the stereotactic MR imaging fiducial markers measured using 3D-MR imaging compared well with the markers' known position embedded in the software (mean error 0.4 mm, maximal error for an individual slice 1.2 mm). For the individual coordinates, only for Y-PC was a difference found between 3D-MR imaging and ventriculography that significantly exceeded half the size of a pixel, the theoretical limit of precision when using a digitized imaging technique. However, the mean difference was smaller than 1 mm. The mean 3D distance between the 3D-MR imaging- and ventriculography-derived coordinates was 1.09 mm for AC, 1.13 mm for PC, and 1.29 mm for the targets. CONCLUSIONS: With these data it is shown that there is sufficient agreement between ventriculography-derived and 3D-MR imaging-derived stereotactic coordinates to justify the use of 3D-MR imaging target determination in frame-based functional stereotactic neurosurgery.     

Volume of white matter hyperintensities is an independent predictor of intelligence quotient and processing speed in children with sickle cell disease

Sickle cell disease can be complicated by cerebral white matter hyperintensities (WMHs), which are associated with diminished neurocognitive functioning. The influence of the total volume of WMHs on the degree of neurocognitive dysfunction has not yet been characterized. In our study of 38 patients (mean age 12·5 years) we demonstrated that a higher volume of WMHs was associated with lower full‐scale intelligence quotient (IQ), verbal IQ, Processing Speed Index and more fatigue. Our results suggest that volume of WMHs is an additional parameter to take into account when planning individual diagnostic and treatment options.     

Diagnostic Accuracy of 4 Commercially Available Semiautomatic Packages for Carotid Artery Stenosis Measurement on CTA

BACKGROUND AND PURPOSE:Semiautomatic measurement of ICA stenosis potentially increases observer reproducibility. In this study, we assessed the diagnostic accuracy and interobserver reproducibility of a commercially available semiautomatic ICA stenosis measurement on CTA and estimated the agreement among different software packages.MATERIALS AND METHODS:We analyzed 141 arteries from 90 patients with TIA or ischemic stroke. Manual stenosis measurements were performed by 2 neuroradiologists. Semiautomatic measurements by using 4 methods (3mensio and comparable software from Philips, TeraRecon, and Siemens) were performed by 2 observers. Diagnostic accuracy was estimated by comparing semiautomatic with manual measurements. Interobserver reproducibility and agreement between different packages was assessed by calculation of the intraclass correlation coefficient and Bland-Altman 95% limits of agreement. False-negative classifications were retrospectively inspected by a neuroradiologist.RESULTS:There was no significant difference in the diagnostic performance of the 4 semiautomatic methods. The sensitivity for detecting ≥50% and ≥70% degree of stenosis was between 76% and 82% and 46% and 62%, respectively. Specificity and overall diagnostic accuracy were between 92% and 97% and 85% and 90%, respectively. The interobserver intraclass correlation coefficient was between 0.83 and 0.96 for semiautomatic measurements and 0.81 for manual measurement. The limits of agreement between each pair of semiautomatic packages ranged from −18%–24% to −33%–31%. False-negative classifications were caused by ulcerative plaques and observer variation in stenosis and reference measurements.CONCLUSIONS:Semiautomatic methods have a low-to-good sensitivity and a good specificity and overall diagnostic accuracy. The high interobserver reproducibility makes semiautomatic stenosis measurement valuable for clinical practice, but semiautomatic measurements should be checked by an experienced radiologist.

Carotid endarterectomy in neurologically symptomatic patients with a 70%–99% stenosis results in a 16% decrease in the absolute risk for an ipsilateral stroke in 5 years. However, endarterectomy is only marginally beneficial for patients with a 50%–69% stenosis and has no positive effect in patients with a <50% stenosis.¹ Therefore, the degree of carotid stenosis is crucial in clinical decision-making, and precise and accurate measurement of the degree of stenosis is mandatory. The stenosis measurements on which these thresholds are based were determined by using conventional angiography, which is considered as the original criterion standard.² Due to neurologic complications related to DSA³ and a good diagnostic accuracy of noninvasive tests, carotid stenosis measurement on CTA or MRA has become the standard in clinical practice.^4,5 However, manual measurement of the degree of stenosis on CTA according to the NASCET method is prone to low interobserver reproducibility and requires experience.^6,7 Semiautomatic methods increase the interobserver reproducibility and accelerate the measurement.^8,9 Furthermore, semiautomatic methods require less observer experience compared with manual measurement.¹⁰ Multiple semiautomatic packages are currently available and used in clinical practice. Because different vendors may use different algorithms,¹¹ the reliability of measurements with different software packages is unclear. To become a valuable clinical tool, the diagnostic accuracy must be further investigated. The goal of this study was to assess the agreement and diagnostic accuracy of 4 commercially available software packages for semiautomatic stenosis measurement compared with manual measurement on CTA and to estimate the interobserver reproducibility and the agreement among different semiautomatic packages.     

Cerebral oxygen metabolism in adults with sickle cell disease

In sickle cell disease (SCD), oxygen delivery is impaired due to anemia, especially during times of increased metabolic demand, and cerebral blood flow (CBF) must increase to meet changing physiologic needs. But hyperemia limits cerebrovascular reserve (CVR) and ischemic risk prevails despite elevated CBF. The cerebral metabolic rate of oxygen (CMRO₂) directly reflects oxygen supply and consumption and may therefore be more insightful than flow-based CVR measures for ischemic risk in SCD. We hypothesized that adults with SCD have impaired CMRO₂ at rest and that a vasodilatory challenge with acetazolamide would improve CMRO₂. CMRO₂ was calculated from CBF and oxygen extraction fraction (OEF), measured with arterial spin labeling and T₂-prepared tissue relaxation with inversion recovery (T₂-TRIR) MRI. We studied 36 adults with SCD without a clinical history of overt stroke, and nine healthy controls. As expected, CBF was higher in patients with SCD versus controls (mean ± SD: 74 ± 16 versus 46 ± 5 mL/100 g/min, P < .001), resulting in similar oxygen delivery (SCD: 377 ± 67 versus controls: 368 ± 42 μmol O₂/100g/min, P = .69). OEF was lower in patients versus controls (27 ± 4 versus 35 ± 4%, P < .001), resulting in lower CMRO₂ in patients versus controls (102 ± 24 versus 127 ± 20 μmol O₂/100g/min, P = .002). After acetazolamide, CMRO₂ declined further in patients (P < .01) and did not decline significantly in controls (P = .78), indicating that forcing higher CBF worsened oxygen utilization in SCD patients. This lower CMRO₂ could reflect variation between healthy and unhealthy vascular beds in terms of dilatory capacity and resistance whereby dysfunctional vessels become more oxygen-deprived, hence increasing the risk of localized ischemia.     

Rupture-Associated Changes of Cerebral Aneurysm Geometry: High-Resolution 3D Imaging before and after Rupture

BACKGROUND AND PURPOSE:Comparisons of geometric data of ruptured and unruptured aneurysms may yield risk factors for rupture. Data on changes of geometric measures associated with rupture are, however, sparse, because patients with ruptured aneurysms rarely have undergone previous imaging of the intracranial vasculature. We had the opportunity to assess 3D geometric differences of aneurysms before and after rupture. The purpose of this study was to evaluate possible differences between prerupture and postrupture imaging of a ruptured intracranial aneurysm.MATERIALS AND METHODS:Using high-quality 3D image data, we generated 3D geometric models before and after rupture and compared these for changes in aneurysm volume and displacement. A neuroradiologist qualitatively assessed aneurysm shape change, the presence of perianeurysmal hematoma, and subsequent mass effect exerted on aneurysm and parent vessels.RESULTS:Aneurysm volume was larger in the postrupture imaging in 7 of 9 aneurysms, with a median increase of 38% and an average increase of 137%. Three aneurysms had new lobulations on postrupture imaging; 2 other aneurysms were displaced up to 5 mm and had changed in geometry due to perianeurysmal hematoma.CONCLUSIONS:Geometric comparisons of aneurysms before and after rupture show a large volume increase, origination of lobulations, and displacement due to perianeurysmal hematoma. Geometric and hemodynamic comparison of series of unruptured and ruptured aneurysms in the search for rupture-risk-related factors should be interpreted with caution.

Unruptured intracranial aneurysms are found in approximately 3% of the population.¹ Once they are detected, the decision for preventive treatment has to be weighed against the risk of rupture, with inherent high case fatality and morbidity.² Prediction of rupture of intracranial aneurysms remains poor, with size as the most important risk factor. However, not all large aneurysms would rupture if left untreated; whereas small aneurysms, which are often left untreated, do sometimes rupture during follow-up. Better predictors are, therefore, needed. Intra-aneurysmal hemodynamic characteristics may have predictive value.^3,4Computational fluid dynamics have been applied to simulate hemodynamic flow patterns in the aneurysm and surrounding vessels to relate hemodynamic characteristics with aneurysmal rupture risk.^4,5 Several studies indeed found differences in flow patterns between ruptured and unruptured aneurysms.^3,4,6 However, if one compares ruptured with unruptured aneurysms, the potential changes of the aneurysm geometry before, during, or after rupture itself are neglected.The rupture of the aneurysm may result in shape changes of the aneurysm due to changes in the aneurysmal sac. These changes potentially alter the aneurysmal or perianeurysmal geometry and its related hemodynamic patterns. It is, therefore, pivotal to know whether changes before, during, or shortly after rupture of aneurysms in themselves affect aneurysm geometry and aneurysm hemodynamics; and if so, what these changes are. Such data are difficult to collect because high-quality images of intracranial aneurysms before and after rupture are rare. We had the opportunity to assess changes in aneurysm geometry associated with rupture in a series of 9 patients by using advanced image registration of high-quality 3D imaging data performed before and after rupture.     

Oral, more than transdermal, estrogen therapy improves lipids and lipoprotein(a) in postmenopausal women: a randomized, placebo-controlled study

OBJECTIVE: To assess the effects of low-dose oral and transdermal estrogen therapy on the lipid profile and lipoprotein(a) [Lp(a)] levels in healthy, postmenopausal women and to study the additional influence of gestodene administration. DESIGN: In a multicenter, randomized, double-blind, placebo-controlled study, 152 healthy, hysterectomized, postmenopausal women received daily either placebo (n = 49), 50 microg transdermal 17beta-estradiol (tE2, n = 33), 1 mg oral 17beta-estradiol (oE2, n = 37), or 1 mg oE2 combined with 25 microg gestodene (oE2 + G, n = 33) for 13 cycles of 28 days, followed by 4 cycles of placebo in each group. Fasting serum concentrations of total, high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol, triglycerides, and Lp(a) were measured at baseline and in cycles 4, 13, and 17. RESULTS: In cycle 13, a significant mean percentage decrease from baseline was found in all treatment groups compared with placebo in total cholesterol (tE2, -4.7%; oE2, -6.9%; oE2 + G, -10.5%) and LDL cholesterol (tE2, -5.8%; oE2, -12.6%; oE2 + G, -13.6%). For both oral groups, the reductions were already significant in cycle 4. None of the treatment groups showed a significant change in HDL cholesterol or triglycerides. In cycle 13, Lp(a) was decreased compared with placebo in the oE2 group (-6.6%) and the oE2 + G group (-8.2%). After washout, all observed changes had returned to baseline level, except for the decreases in total and LDL cholesterol in the oE2 + G group. CONCLUSIONS: Oral E2 and E2 + G, and to a lesser extent transdermal E2, decreased total and LDL cholesterol. Lp(a) was lowered only by the oral treatments.     

Perfusion CT to evaluate the effect of transluminal angioplasty on cerebral perfusion in the treatment of vasospasm after subarachnoid hemorrhage

Introduction  

Splanchnic ischemia (SI) and increased gut permeability (GP) have been described in acute brain injury (ABI), although their incidence and relation to the type and severity of injury are uncertain. The aim of this study was to evaluate the incidence of both abnormalities in a series of patients with severe ABI secondary to intracranial hemorrhage (ICH) managed with a resuscitation protocol pursuing adequate cerebral and systemic hemodynamics.     

Observer variation in MRI evaluation of patients suspected of lumbar disk herniation

OBJECTIVE: Our objective was to assess observer variation in MRI evaluation in patients suspected of lumbar disk herniation. SUBJECTS AND METHODS: Two experienced neuroradiologists independently evaluated 59 consecutive patients with lumbosacral radicular pain. Per patient, three levels (L3-L4 through L5-S1) and the accompanying roots were evaluated on both sides. For each segment, the presence of a bulging disk or a herniation and compression of the root was reported. Images were interpreted twice: once before and once after disclosure of clinical information. Interobserver agreement was expressed as unweighted kappa values. RESULTS: Without clinical information, interobserver agreement for the presence of herniation or bulging disk was moderate (full agreement, 84%; kappa = 0.63; 95% confidence interval [CI], 0.53-0.72). Of a total of 352 segments evaluated, there was disagreement on 58 segments (17%): bulging disk versus no defect in 26 (7.4%), bulging disk versus herniation in five (1.4%), and hernia versus no defect in 27 (7.7%). With clinical information, twice as many bulging disks were reported but no new herniations were detected. Agreement slightly decreased, but not significantly (full agreement, 77%; kappa = 0.59; 95% CI, 0.49-0.69; p = 0.12). CONCLUSION: On average, more than 50% of interobserver variation in MRI evaluation of patients with lumbosacral radicular pain is caused by disagreement on bulging disks. Knowledge of clinical information does not influence the detection of herniations but lowers the threshold for reporting bulging disks.