Search

Background The potential morbidity of cerebral ischemia after carotid endarterectomy (CEA) has been recognized, but its reported incidence varies widely. Objective To prospectively evaluate the development of cerebral ischemic complications in patients treated by CEA at a high-volume cerebrovascular center. Methods Fifty patients with moderate or severe carotid stenosis awaiting CEA were studied with perioperative diffusion-weighted imaging of the brain and standardized neurological evaluations. Microsurgical CEA was performed by 1 of 2 vascular neurosurgeons. Radiological studies were evaluated by faculty neuroradiologists who were blinded to the details of the clinical situation. Results Preoperative diffusion-weighted imaging studies were performed within 24 hours of surgery. A second study was obtained within 24 (92% of patients), 48 (4% of patients), or 72 (4% of patients) hours after surgery. Intraluminal shunting was used in 1 patient (2%), and patch angioplasty was used in 2 patients (4%). No patient had diffusion-weighted imaging evidence of procedure-related cerebral ischemia. Nonischemic complications consisted of postoperative confusion in an 87-year-old man with a urinary tract infection and a marginal mandibular nerve paresis in another patient. Radiological studies were normal in both patients. Conclusion CEA is a relatively safe procedure that may be performed with an acceptable risk of cerebral ischemia in select patients. The low rate of ischemic complications associated with CEA sets a standard to which other carotid revascularization techniques should be held. The current results are presented with a discussion of the senior author's preferred surgical technique and a brief review of the literature.

BACKGROUND AND PURPOSE: Relative cerebral blood volume (rCBV) accuracy can vary substantially depending on the dynamic susceptibility-weighted contrast-enhanced (DSC) acquisition and postprocessing methods, due to blood-brain barrier disruption and resulting T1-weighted leakage and T2- and/or T2*-weighted imaging (T2/T2*WI) residual effects. We set out to determine optimal DSC conditions that address these errors and maximize rCBV accuracy in differentiating posttreatment radiation effect (PTRE) and tumor. MATERIALS AND METHODS: We recruited patients with previously treated high-grade gliomas undergoing image-guided re-resection of recurrent contrast-enhancing MR imaging lesions. Thirty-six surgical tissue samples were collected from 11 subjects. Preoperative 3T DSC used 6 sequential evenly timed acquisitions, each by using a 0.05-mmol/kg gadodiamide bolus. Preload dosing (PLD) and baseline subtraction (BLS) techniques corrected T1-weighted leakage and T2/T2*WI residual effects, respectively. PLD amount and incubation time increased with each sequential acquisition. Corresponding tissue specimen stereotactic locations were coregistered to DSC to measure localized rCBV under varying PLD amounts, incubation times, and the presence of BLS. rCBV thresholds were determined to maximize test accuracy (average of sensitivity and specificity) in distinguishing tumor ( n = 21) and PTRE ( n = 15) samples under the varying conditions. Receiver operator characteristic (ROC) areas under the curve (AUCs) were statistically compared. RESULTS: The protocol that combined PLD (0.1-mmol/kg amount, 6-minute incubation time) and BLS correction methods maximized test AUC (0.99) and accuracy (95.2%) compared with uncorrected rCBV AUC (0.85) and accuracy (81.0%) measured without PLD and BLS ( P = .01). CONCLUSIONS: Combining PLD and BLS correction methods for T1-weighted and T2/T2*WI errors, respectively, enables highly accurate differentiation of PTRE and tumor growth.

A nondemented, 55-year-old woman with a 20-year history of relapsing-remitting multiple sclerosis (MS) recently began having significant difficulties performing her job after several years of successful employment. While the patient acknowledged that others considered her job performance as being below standards, she did not subjectively experience any change in her cognitive functioning that would negatively impact job performance. She had no explanation as to why her job performance was now considered unsatisfactory. She also appeared to be in no distress over her situation. Was the patient's unawareness a form of anosognosia or psychological denial of her clinical condition? We provide neuropsychological, neuroimaging, and behavioral descriptions of the patient that suggest that the underlying disturbance appeared to be a neuropsychologically based, impaired self-awareness (ISA). Clinical suggestions are provided for distinguishing between ISA and denial of disability (DD) in MS patients.

Multiple clinical trials have demonstrated the efficacy of endarterectomy in selected groups of patients based primarily on percent diameter stenosis. Although measurement of stenosis in the clinical trials was established by conventional angiography, there is considerable interest in noninvasive alternatives. Magnetic resonance angiography, performed using time-of-flight methods or with contrast enhancement, is one of several alternatives for noninvasive carotid evaluation. Screening examinations are routinely performed for carotid stenosis. Preoperative evaluations based on one or a combination of noninvasive tests have been proposed, although these proposals are the subject of ongoing controversy. Evaluation of the vertebral arteries is more difficult and less well studied: however, the increasing availability of therapies for posterior circulation atherosclerotic narrowing is resulting in increased interest in this problem.

MR imaging offers a high-resolution technique for examining the structures of the internal auditory canal and cerebellopontine angle. Vestibular schwannoma may be detected sensitively with contrast-enhanced or three-dimensional T2-weighted MR sequences. This review examines the imaging findings of primary and residual vestibular schwannomas and their mimics.

✓ Magnetic resonance (MR) angiography offers a safe, noninvasive alternative to conventional angiography in patients with suspected carotid stenosis; however, it tends to overestimate the severity of stenosis. Loss of the MR signal with a resulting flow gap is a frequent finding in cases of high-grade stenosis. The authors undertook this study to define the range of carotid stenosis associated with a flow gap on two-dimensional time-of-flight (2DTF)-MR angiography. Blinded evaluations were made of 102 common carotid bifurcations in 51 patients who had undergone both conventional angiography and 2DTF-MR angiography. The percent of diameter stenosis was calculated from the conventional angiogram using the method adopted by the Asymptomatic Carotid Atherosclerosis Study (ACAS) trial. An MR flow gap was noted if there was a segment of the vessel that was completely free of signal with a reappearance of the signal distally. According to conventional angiography, the minimum percentage of stenosis associated with a flow gap is 56%. Flow gaps were present in 20 of 22 arteries (sensitivity 91%) with stenosis of 60% or more and in two of the 66 arteries (specificity 97%) with less than 60% stenosis. Flow gaps were present in all arteries with stenosis of 70% or more. Complete occlusion was correctly identified in 10 of 10 cases. These results demonstrate that the presence of a flow gap on 2DTF-MR angiography is a reliable marker of clinically significant carotid stenosis (measuring 60% or more), with sensitivity and specificity comparable to duplex carotid ultrasound. In addition, MR angiography can be used to screen the intracranial circulation for significant vascular pathology in patients being considered for carotid endarterectomy.

✓ Thirty patients were treated surgically for spinal epidural hematoma (SEH). Twelve of these cases resulted from spinal surgery, seven from epidural catheters, four from vascular lesions, three from anticoagulation medications, two from trauma, and two from spontaneous causes. Pain was the predominant initial symptom, and all patients developed neurological deficits. Eight patients had complete motor and sensory loss (Frankel Grade A); six had complete motor loss but some sensation preserved (Frankel Grade B); and 16 had incomplete loss of motor function (10 patients Frankel Grade C and six patients Frankel Grade D). The average interval from onset of initial symptom to maximum neurological deficit was 13 hours, and the average interval from onset of symptom to surgery was 23 hours. Surgical evacuation of the hematoma was performed in all patients; 26 of these improved; four remained unchanged, and no patients worsened (mean follow up 11 months). Complete recovery (Frankel Grade E) was observed in 43% of the patients and functional recovery (Frankel Grades D or E) was observed in 87%. One postoperative death occurred from a pulmonary embolus (surgical mortality 3%). Preoperative neurological status correlated with outcome; 83% of Frankel Grade D patients recovered completely compared to 25% of Frankel Grade A patients. The rapidity of surgical intervention also correlated with outcome; greater neurological recovery occurred as the interval from symptom onset to surgery decreased. Patients taken to surgery within 12 hours had better neurological outcomes than patients with identical preoperative Frankel grades whose surgery was delayed beyond 12 hours. This large series of SEH demonstrates that rapid diagnosis and emergency surgical treatment maximize neurological recovery. However, patients with complete neurological lesions or long-standing compression can improve substantially with surgery.

A new scheme for assignment of echoes to views in fast spin-echo imaging was developed. The scheme places early and late echoes in alternating lines of the periphery of k-space; continued alternation of echoes arising closer to the middle of the echo train encodes the central portion of k-space. The scheme has two effects: a) The echo-to-echo signal decay that usually gives rise to multiple faint ghosts, now yields a single Nyquist ghost that is removed by phase over-sampling. b) Mapping earlier echoes (and thus more energy) to the periphery of k-space yields sharper edges.

BACKGROUND AND PURPOSE: Quantifying MVA rather than MVD provides better correlation with survival in HGG. This is attributed to a specific “glomeruloid” vascular pattern, which is better characterized by vessel area than number. Despite its prognostic value, MVA quantification is laborious and clinically impractical. The DSC-MR imaging measure of rCBV offers the advantages of speed and convenience to overcome these limitations; however, clinical use of this technique depends on establishing accurate correlations between rCBV, MVA, and MVD, particularly in the setting of heterogeneous vascular size inherent to human HGG. MATERIALS AND METHODS: We obtained preoperative 3T DSC-MR imaging in patients with HGG before stereotactic surgery. We histologically quantified MVA, MVD, and vascular size heterogeneity from CD34-stained 10-μm sections of stereotactic biopsies, and we coregistered biopsy locations with localized rCBV measurements. We statistically correlated rCBV, MVA, and MVD under conditions of high and low vascular-size heterogeneity and among tumor grades. We correlated all parameters with OS by using Cox regression. RESULTS: We analyzed 38 biopsies from 24 subjects. rCBV correlated strongly with MVA (r = 0.83, P < .0001) but weakly with MVD (r = 0.32, P = .05), due to microvessel size heterogeneity. Among samples with more homogeneous vessel size, rCBV correlation with MVD improved (r = 0.56, P = .01). OS correlated with both rCBV (P = .02) and MVA (P = .01) but not with MVD (P = .17). CONCLUSIONS: rCBV provides a reliable estimation of tumor MVA as a biomarker of glioma outcome. rCBV poorly estimates MVD in the presence of vessel size heterogeneity inherent to human HGG.

The recent demonstration of the efficacy of carotid endarterectomy in certain patients emphasizes the advantages of having a noninvasive, accurate means of evaluating the carotid arteries. Advances in magnetic resonance (MR) angiography now allow accurate depiction of the carotid arteries that may be adequate for surgical planning in many cases. This report examines the accuracy of MR angiography compared with that of conventional angiography in symptomatic patients undergoing carotid endarterectomy and compares them with surgical findings. Twenty-one carotid arteries in 20 patients were treated surgically for severe stenosis or occlusion. Preoperatively, all patients had both MR and conventional angiograms, which were interpreted on a five-grade scale by two independent neuroradiologists who were unaware of the patient's clinical history. The two studies were highly correlated, particularly in the case of severe stenosis and occlusion. There were no false-negative MR studies that missed surgically significant lesions. In two cases, MR angiography overestimated the stenosis by one grade. On MR angiography, surgically significant stenosis appears as focal areas of signal intensity loss at the level of stenosis with reappearance of the signal distally. If the distal signal intensity does not reappear, the artery is likely to be occluded. In symptomatic patients, MR angiograms that demonstrate a flow-void gap with distal reappearance at a site consistent with the symptoms may be adequate as the sole preoperative study. Three patients who underwent carotid endarterectomy on this basis are presented. The factors that contribute to artifactual and overestimated stenosis are reviewed.

To assess the clinical efficacy of two-dimensional time-of-flight magnetic resonance (MR) angiography in the evaluation of carotid artery stenosis, a group of patients was evaluated in which 73 vessels were studied with both MR and conventional angiography. Four experienced neuroradiologists each scored both the MR and conventional angiograms in a blinded manner by using a standardized scoring scheme. Comparison of the scores revealed a high degree of correlation. In particular, MR angiography served to discriminate reliably between mildly narrowed and severely narrowed or occluded vessels. Furthermore, severe stenoses were accurately discriminated from occlusions in all cases. MR angiography is a robust and accurate modality for the characterization of carotid artery stenosis. It is useful in conjunction with routine MR imaging of the brain in the evaluation of the patient with suspected carotid arterial disease.

Correlation of locations of sacral insufficiency fractures is made to regions of stress depicted by finite element analysis derived from biomechanical models of patient activities.Sacral insufficiency fractures occur at consistent locations. It was postulated that sacral anatomy and sites of stress within the sacrum with routine activities in the setting of osteoporosis are foundations for determining patterns for the majority of sacral insufficiency fractures.The predominant vertical components of sacral insufficiency fractures most frequently occur bilaterally through the alar regions of the sacrum, which are the thickest and most robust appearing portions of the sacrum instead of subjacent to the central sacrum, which bears the downward force of the spine.First, the exact locations of 108 cases of sacral insufficiency fractures were catalogued and compared to sacral anatomy. Second, different routine activities were simulated by pelvic models from CT scans of the pelvis and finite element analysis. Analyses were done to correlate sites of stress with activities within the sacrum and pelvis compared to patterns of sacral insufficiency fractures from 108 cases.The sites of stress depicted by the finite element analysis walking model strongly correlated with identical locations for most sacral and pelvic insufficiency fractures. Consistent patterns of sacral insufficiency fractures emerged from the 108 cases and a biomechanical classification system is introduced. Additionally, alteration of walking mechanics and asymmetric sacral stress may alter the pattern of sacral insufficiency fractures noted with hip pathology (P = 0.002).Locations of sacral insufficiency fractures are nearly congruous with stress depicted by walking biomechanical models. Knowledge of stress locations with activities, cortical bone transmission of stress, usual fracture patterns, intensity of sacral stress with different activities, and modifiers of walking mechanics may aid medical management, interventional, or surgical efforts.

BACKGROUND AND PURPOSE: Differentiating tumor growth from posttreatment radiation effect (PTRE) remains a common problem in neuro-oncology practice. To our knowledge, useful threshold relative cerebral blood volume (rCBV) values that accurately distinguish the 2 entities do not exist. Our prospective study uses image-guided neuronavigation during surgical resection of MR imaging lesions to correlate directly specimen histopathology with localized dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC) measurements and to establish accurate rCBV threshold values, which differentiate PTRE from tumor recurrence. MATERIALS AND METHODS: Preoperative 3T gradient-echo DSC and contrast-enhanced stereotactic T1-weighted images were obtained in patients with high-grade glioma (HGG) previously treated with multimodality therapy. Intraoperative neuronavigation documented the stereotactic location of multiple tissue specimens taken randomly from the periphery of enhancing MR imaging lesions. Coregistration of DSC and stereotactic images enabled calculation of localized rCBV within the previously recorded specimen locations. All tissue specimens were histopathologically categorized as tumor or PTRE and were correlated with corresponding rCBV values. All rCBV values were T1-weighted leakage-corrected with preload contrast-bolus administration and T2/T2*-weighted leakage-corrected with baseline subtraction integration. RESULTS: Forty tissue specimens were collected from 13 subjects. The PTRE group (n = 16) rCBV values ranged from 0.21 to 0.71, tumor (n = 24) values ranged from 0.55 to 4.64, and 8.3% of tumor rCBV values fell within the PTRE group range. A threshold value of 0.71 optimized differentiation of the histopathologic groups with a sensitivity of 91.7% and a specificity of 100%. CONCLUSIONS: rCBV measurements obtained by using DSC and the protocol we have described can differentiate HGG recurrence from PTRE with a high degree of accuracy.

Study design Biomechanical load-to-failure findings correlated with anatomic dissection measurements and intact (prefailure) 3-Tesla (3-T) magnetic resonance images (MRI). Objective To better understand why the same distractive force to the head can result in occipitoatlantal dislocation (OAD) in some individuals and atlantoaxial dislocation (AAD) in others. Summary of background data Distraction injuries to the cranio-vertebral junction have been studied biomechanically but have not been studied relative to ligamentous anatomic variations. We theorized that morphologic variations in the ligaments should influence the injury pattern during axial distraction. Methods After obtaining 3-T MRI scans, 10 occiput-C2 specimens were loaded to failure under axial tension. Direct anatomic measurements were also obtained from the distracted and injured specimens. Results AAD was observed in 7 specimens (mean force +/- standard deviation 1229 +/- 181 N) at a significantly higher magnitude than OAD, which was observed in 3 specimens (823 +/- 127 N; P = 0.009, nonpaired t test). In OAD specimens, the superior cruciate ligament (SCL), which was smaller than the inferior cruciate ligament (ICL), failed. The apical ligament was unidentifiable in these 3 specimens. In 5 of the 7 AAD specimens, the ICL ruptured and was smaller than the SCL. In the remaining 2 specimens, both SCL and ICL ruptured. The apical ligament, which ruptured, was identifiable in all 7 specimens. Conclusion Axial distraction across the cranio-vertebral junction can produce either OAD or AAD. The SCL and ICL dimensions, alar ligament orientations, and apical ligament presence may affect the injury site. Visualization with 3-T MRI allows better understanding of the injury mechanism and location, which is important clinically in selecting single- or multilevel fixation.

OBJECTIVE: Instability of the craniocervical junction can cause neurological sequelae or pain. Stability of this region depends on extensive ligamentous support structures, most of which are well studied by magnetic resonance imaging (MRI) scanning. Although the contribution of the accessory atlantoaxial ligament to rotational stability has been described, this ligament has not been identified by imaging. Therefore, we investigated the imaging characteristics of this ligament and its relationship to the ligamentous complex of the craniocervical junction using the high resolution offered by 3-T MRI scans. METHODS: Ten healthy volunteers underwent MRI scanning at 3-T to determine the normal anatomy of this ligament. RESULTS: The atlantoaxial (C1-C2) segment of the ligament was identified in all 10 subjects bilaterally and symmetrically. Its mean dimensions were 2.8 x 1.8 mm. In four out of 10 subjects, the occipitoatlantal (C0-C1) segment was observed. At this level, the mean dimensions of the ligament were 1.6 x 1.2 mm on the right and 1.8 x 1.4 mm on the left. Its size varied between the right and left sides. CONCLUSION: The accessory atlantoaxial ligament can be visualized using high-resolution MRI scans at 3-T. The ligament was most consistent and robust at C1-C2. The ligament may, therefore, contribute to rotational stability at this level. Future studies will determine the biomechanical importance of this ligament, especially in the setting of trauma.

A recent study reporting pontine lesions on magnetic resonance imaging in three patients with idiopathic narcolepsy postulated that the lesions represented tissue change secondary to long duration of disease. We studied twelve narcoleptic patients with MRI to validate these findings. The diagnosis of narcolepsy was established with both clinical and electrophysiological criteria in all twelve patients. Pontine lesions were present in two patients, both of whom were hypertensive. The lesions were associated with similar lesions in the hemispheres and were indistinguishable from ischemic change. No lesions were evident in the other ten patients, eight of whom were normotensive, and six of whom had narcolepsy for more than 37 years. We were unable to confirm the presence of pontine lesions specific to narcolepsy.

BACKGROUND AND PURPOSE: Our aim was to quantitate the range of error in measurement of percent diameter carotid stenosis using conventional angiography in order to estimate the misclassification rate in selecting patients for carotid endarterectomy. METHODS: A secondary or meta-analysis of published data regarding carotid stenosis measurement error associated with angiography yielded a narrow range of standard deviation across several studies using different measurement protocols. A simulation of the measurement process was developed to model this error and allow estimation of misclassification rates compared with true values for stenosis. RESULTS: A standard deviation of 8% describes the average error observed at 60% diameter stenosis across a number of studies. Using the measurement model, for a population with 30% prevalence of 60% stenosis, this finding implies a misclassification rate of approximately 4% overall for conventional angiography. CONCLUSION: Like all diagnostic tests, angiography is associated with measurement error. This does not affect the results of carotid stenosis therapy trials using angiography but does need to be taken into account when evaluating noninvasive alternative tests for carotid stenosis.

BACKGROUND AND PURPOSE: Periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER or PROP) is an effective means of compensating for head motion during MR imaging in adults. The aim of this study was to assess the value of this novel technique in unsedated children. METHODS: PROP T2-weighted fast spin-echo (FSE) imaging (TR/TE/NEX, 4000/83/2; 50 seconds) and T2-weighted single-shot FSE (SS-FSE) imaging (19,929/92/0.5; imaging time, 25 seconds) were performed in 35 unsedated children (mean age, 4.7 years ± 4.2) who were undergoing brain MR imaging. Two observers assessed unlabelled images for motion artifact, other artifacts, visibility of pathology, and the preferred image overall. Sequences were compared by using the χ(2) test and concordant data from both observers. RESULTS: Both PROP and the SS-FSE imaging offered equal degrees of motion correction. Metallic artifacts were worse on PROP imaging, likely because of a higher receiver bandwidth (P < .001, χ(2) test). Pathology was present in 28 subjects and equally well seen on PROP and SS-FSE images. Overall, PROP was preferred, largely because of its improvements in image contrast (P < .001, χ(2) test). CONCLUSION: SS-FSE imaging and PROP provide equal motion correction, although PROP enables better assessment of the brain parenchyma.

BACKGROUND AND PURPOSE: The aim of this study was to assess the effect of zero-filled interpolation (ZIP) on measurements of the cervical arteries because its benefits on the accuracy and precision of measurements in medium-sized arteries remains unknown. METHODS: Three observers measured 36 computer-simulated vessels (2–6.8 mm) and 130 normal cervical vessels (assessed with two-dimensional time-of-flight MR angiography) from 512–, 256–, and 256–ZIP matrix source images. The accuracy and precision of measurement was assessed for each matrix by using the Student t test and F test of variance, respectively. The effect of vessel size and matrix placement on measurement error was determined by means of linear regression and the Student t test, respectively. RESULTS: No significant difference was observed between simulated measurements obtained on the 512 matrix and their true value. The 256 matrix caused overestimation of vessel diameter compared with 512 matrix (mean bias, 0.3 mm for computer-simulated vessels and 0.1 mm for normal vessels). This effect was reduced with ZIP, by a mean of 0.1 mm for both groups (P < .03). Precision was not affected by the matrix size or ZIP, and vessel size and matrix placement did not alter the measurement error. CONCLUSION: Vessel diameter is overestimated on 256-matrix MR angiographic source images. ZIP reduces this overestimation; however, the effect is small and unlikely to be clinically important.

To compare periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) multishot fast spin-echo diffusion-weighted magnetic resonance (MR) imaging with single-shot echo-planar diffusion-weighted MR imaging for image quality and visualization of acute cerebral infarction.Seventy subjects (35 men, 35 women; mean age, 55 years +/- 24 [SD]) who were suspected of having acute cerebral infarction (symptom duration, 2.8 days +/- 2.7) underwent PROPELLER and echo-planar MR imaging (b = 1,000 sec/mm(2)). Two neuroradiologists compared unlabeled images for presence of artifacts, visualization of infarction, and their preference of images. Interobserver agreement and image comparison were assessed by using the kappa statistic and the chi(2) test, respectively.PROPELLER MR imaging reduced susceptibility artifacts (n = 70 subjects), which limited visualization of temporal (echo-planar, n = 64; PROPELLER, n = 0; P.01, chi(2) test), frontal (echo-planar, n = 58; PROPELLER, n = 1; P.01), and parietal lobes (echo-planar, n = 5; PROPELLER, n = 0; P.05) and cerebellum (echo-planar, n = 36; PROPELLER, n = 0; P.01) and brainstem (echo-planar, n = 23; PROPELLER, n = 0; P.01). Acute infarction (n = 31 subjects) was better demonstrated at PROPELLER MR imaging (PROPELLER better, n = 18; echo-planar better, n = 1; PROPELLER and echo-planar equal, n = 12; P.01, chi(2) test). PROPELLER MR imaging was preferred in all (n = 70) but one case in which the lesion lay within the intersection gap (PROPELLER preferred, n = 69; echo-planar preferred, n = 1; P.01, chi(2) test).With a short increase in imaging time, PROPELLER MR imaging offers better image quality and detection of acute cerebral infarction than does echo-planar MR imaging.

It is controversial whether an intracerebral hematoma (ICH) causes ischemia of surrounding brain. By virtue of its high sensitivity to acute cerebral infarction, diffusion-weighted imaging (DWI) helps answer this question. We used this technique to assess the parenchyma surrounding ICH for restricted diffusion. Echoplanar DWI (b 1000 s/mm(2)) and conventional MRI sequences were performed in 30 subjects (symptom duration 7-75 h) with primary ICH, mean volume: 13+/-15 cm(3). We calculated mean apparent diffusion coefficients (ADC) within high signal regions around the hematoma on DWI or T2-weighted images and within the ICH itself, comparing them to the contralateral brain. We used the Student's t -test to examine for differences between these regions and linear regression to relate changes to the age of the ICH. A thin rim of high signal on DWI and a wider rim on T2-weighted images surrounded all hematomas. The ADC within the rim on DWI showed a maximum reduction of 40%, in two patients imaged within 10 h of symptom onset. They rose during the first day (r(2)=0.84; P0.03) and then showed a mild decrease, becoming the same as ADC in other areas of the brain (r(2)=0.5; P0.03). The rim on T2-weighting showed a mean increase of 50% and ADC within the ICH were reduced by a mean of 38%; these variations showed no relationship with ICH age and no group showed any relationship with ICH size. The ADC within the three regions was significantly different from each other. The presence of restricted diffusion in the parenchyma surrounding ICH provides support for secondary neuronal damage.

While head motion is considered a significant problem in magnetic resonance imaging (MRI), there is no data to quantify its extent, severity, or effect on image quality. PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) MRI offers a novel means of quantifying and compensating for head motion. We performed axial T2-weighted PROPELLER (motion corrected: P-CR; uncorrected: P-UNCR) and conventional MRI (CONV), with equal scan times, in five normal volunteers and 35 clinical subjects. Volunteers were examined lying still and performing two separate head movements (shake "no" and nod "yes") to assess detection and compensation of in-plane motion by PROPELLER MRI. Images were examined by three radiologists for motion artifact and for overall image quality. Head rotation and translation was detected in all subjects during each slice acquisition, with expected changes occurring with volunteer head motion. Motion artifact was less commonly seen on PROPELLER than CONV MR (chi(2) test P < 0.001). PROPELLER was preferred over CONV in all subjects (P < 0.05) and P-CR was judged superior to P-UNCR (P = 0.02). Intracranial pathology was equally or better demonstrated with PROPELLER. PROPELLER MRI offers a means of quantifying head motion, reducing motion artifact, and improving image quality.

Study Design. Seven cadaveric cervical spines were implanted with a porous tantalum spacer and a titanium alloy spacer, and their radiographic and imaging characteristics were evaluated. Objective. To determine the radiographic characteristics of porous tantalum and titanium implants used as spacers in the cervical spine. Summary of Background Data. Anterior decompressive surgery of the disc space or the vertebral body creates a defect that frequently is repaired with autologous bone grafts to promote spinal fusion. Donor site morbidity, insufficient donor material, and additional surgical time have spurred the development of biomaterials to replace or supplement existing spinal reconstruction techniques. Although the promotion of a solid bony fusion is critical, the implanted biomaterial should be compatible with modern imaging techniques, should allow visualization of the spinal canal and neural foramina, and should permit radiographic assessment of bony ingrowth. Methods. Cadaveric spines containing the implants were imaged with plain radiography, computerized tomography, and magnetic resonance imaging. The image distortion produced by the implants was determined qualitatively and quantitatively. Results. The tantalum and titanium spacers were opaque on plain radiographic films. On computed tomographic scans, more streak artifact was associated with the tantalum implants than with the titanium. On magnetic resonance imaging, the porous tantalum implant demonstrated less artifact than did the titanium spacer on T1- and T2-weighted spin echo and on T2*-weighted gradient-echo magnetic resonance images. Overall, the tantalum implant produced less artifact on magnetic resonance imaging than did the titanium spacer and therefore allowed for better visualization of the surrounding bony and neural structures. Conclusion. The material properties of titanium and porous tantalum cervical interbody implants contribute to their differential appearance in different imaging methods. The titanium implant appears to image best with computed tomography, whereas the porous tantalum implant produces less artifact than does the titanium implant on several magnetic resonance imaging sequences.

✓ Juvenile active ossifying fibroma is a rare lesion seldom seen by neurosurgeons. It originates in the paranasal sinuses during childhood, grows slowly, and encroaches on adjacent orbital and cranial compartments. In the past 3 years, four patients with this lesion were seen (three men and one woman; mean age 28 years). The clinical presentations were different with each patient: sinusitis, meningitis, periorbital pain, and a unique case of a juvenile active ossifying fibroma presenting with high-grade internal carotid artery stenosis and ischemic symptoms. Three patients were treated by transfacial approaches: two with a transfrontal—nasal approach and one with a transfrontal—nasoorbital approach. Two open resections resulted in gross-total excision and no recurrence as of the 2-year follow-up review. In the third patient, the tumor-encased carotid artery was preserved at the expense of a complete resection; that patient underwent superficial temporal artery—middle cerebral artery bypass and remains without ischemic symptoms or tumor recurrence at 2 years. The fourth patient underwent three subtotal endoscopic resections and is also without symptomatic recurrence at 2 years. Three points must be made concerning these lesions. First, the clinical and radiographic characteristics of juvenile active ossifying fibroma may not be easily recognized by neurosurgeons, which could lead to misdiagnosis and mismanagement of these lesions. Second, this tumor can encase the carotid artery and cause severe stenosis or occlusion. Third, complete resection of the tumor is required to effect a cure, and transfacial approaches, which give wide exposure of the sinuses, appear to yield better, more radical resections than endoscopic procedures.

Multiple gradient echoes are generated for each RF echo of a Carr-Purcell-Meiboom-Gill (CPMG) train. Independently, phase-encoded fast spin-echo images are obtained from the different gradient echoes. Presently, three images are formed from three gradient-echoes from each of four RF echoes. The two peripheral gradient echo images are encoded for a late effective TE, then summed after reconstruction: this image has decreased fat intensity and increased susceptibility contrast compared with fast spin echo. The central gradient echoes yielded another image of intermediate contrast useful for neuroimaging. Raw data from the variously timed gradient echoes are not combined as they are in GRASE.

RATIONALE AND OBJECTIVES The authors determine the reliability of centralized versus noncentralized (site-based) measurement of angiographic stenosis of patients enrolled into the multicenter, prospective, Asymptomatic Carotid Atherosclerosis Study by angiographic studies. METHODS Percent agreements and correlations of 244 masked and prospectively interpreted angiograms were calculated for comparison of centralized and noncentralized readers measuring the percent carotid stenosis from the same angiographic studies. Univariate summary statistics for differences in percent stenoses were calculated for these readings. RESULTS Agreement between readings were 88.5% and 91.8% with kappa statistics of 0.77 and 0.73 for > or = 60% and > or = 80% stenosis, respectively, for comparison of 33 centers to the designated central reader. Comparison between the designated central reader and a second central reader derived percent agreements of 85.0% and 86.5% with kappa statistics of 0.69 and 0.41 for > or = 60% and > or = 80% stenoses, respectively, for arteries selected from the original group. Hence, agreement was slightly better between the enrolling centers and the designated central reader than between the two central readers. CONCLUSIONS Both centralized and noncentralized (site-based) methods of angiographic measurement of stenosis are equally reliable for large, prospective, masked, multicenter trials when quality control measures are instituted to ensure uniform application of eligibility criteria.

THIS REPORT DESCRIBES the first clinical use of newly developed titanium clips in the treatment of 16 patients with subarachnoid hemorrhage. There were no immediate or delayed complications related to the titanium clips. Thirteen patients had good outcomes, and one patient had moderate disabilities (mean follow-up, 5.4 mo). Two patients with Hunt and Hess Grade IV hemorrhages died postoperatively. The average cross-sectional areas of clip artifact on postoperative magnetic resonance imaging studies was 0.96, 1.36, and 1.05 cm 2 on T1-, T2-, and intermediate-weighted images, respectively. In comparison, a matched control group with cobalt alloy clips had average cross-sectional areas of 3.13, 3.70, and 2.81 cm 2 on T1-, T2-, and intermediate-weighted images, respectively. The average artifact volumes on gradient echo magnetic resonance images for titanium and cobalt alloy clips were 1.8 and 10.1 cm 3 , respectively. In addition, the gap on magnetic resonance imaging angiograms from clip artifacts was 0.9 cm with titanium and 2.6 cm with cobalt alloy clips. In conclusion, titanium aneurysm clips seem to be safe and effective and seem to reduce clip artifacts on magnetic resonance imaging threefold, compared with commercially available cobalt alloy clips. Because of this important advantage over conventional clips, titanium clips should be considered for routine use in aneurysm surgery.

2081 Background: This study establishes Perfusion MRI (pMRI) correlation with tissue microvasculature and accuracy to predict histopathologic diagnosis of tumor recurrence or post-treatment radiati...

Purpose: This study uses spatially accurate image-guided tissue analysis to evaluate the correlation between Perfusion MRI (pMRI) and tissue microvascular density parameters as markers for tumor recurrence and treatment response in high-grade glioma (HGG). Methods: Following Institutional Review Board approval, we recruited previously treated (including chemo-radiation therapy) HGG patients undergoing surgical re-resection of new enhancing lesions on surveillance MRI. Preoperatively, we acquired pMRI and contrast-enhanced stereotactic T1-Weighted (T1W) MRI data sets. Intraoperatively, we recorded stereotactic locations of multiple biopsies based on T1W data sets that guided surgery. Following surgery, we coregistered pMRI and T1W data sets to calculate localized relative cerebral blood volume (rCBV) for each stereotactic specimen location. For each specimen, we performed 1) standard H&E staining to diagnose tumor recurrence or post-treatment radiation effect (PTRE); and 2) immunohistochemical analysis with CD34 to highlight tissue vessels. We analyzed CD-34 stained slides with Axiovision Automeasure 3.4 (Zeiss, Germany) to calculate both total microvessel number (MVN) and total microvessel area (MVA), each normalized to total slide specimen area (μm2). We calculated Pearson correlations to establish relationships between a) rCBV and MVN; and b) rCBV and MVA. We also performed t-test to compare MVN, MVA, and rCBV values between tumor and PTRE samples. A neuroradiologist performed all coregistration and pMRI calculations, and a neuropathologist analyzed all tissue specimens, without knowledge of corresponding data. A biostatistician performed all statistical comparisons. Results: In this preliminary study, we included 16 tissue specimens (from 8 subjects), each diagnosed as either tumor (n=7) or PTRE (n=9). We successfully calculated localized rCBV and determined both MVA and MVN for each specimen. The rCBV values showed highest correlation with total vessel area (MVA) (r=0.65, p=0.007) and slightly less correlation with vessel number (MVN) (r=0.52, p=0.04). Tumor showed significantly higher values than PTRE for all parameters: rCBV (1.87 + 0.82 versus 0.78 + 0.2, p=.002); MVA (0.22 + 0.03 versus 0.04 + 0.007, p=0.0001); and MVN (0.0068 + 0.001 versus. 0.0016 + 0.0006, p=0.0004). Conclusion: These preliminary results show the promise of Perfusion MRI to non-invasively estimate tissue microvessel density and distinguish tumor recurrence from treatment effects. The current study is ongoing to confirm results in a larger patient population. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3748.

To assess the usefulness of magnetic resonance (MR) angiography in the characterization of intracranial arterial stenosis and occlusion, a three-dimensional time-of-flight method was compared with conventional angiography in 214 vessels in 29 patients. Studies were independently interpreted by two neuroradiologists who scored each vessel as normal, narrowed, or occluded. Overall, 97% of normal vessels and 100% of occlusions were correctly graded. Sixty-one percent of stenoses were graded correctly; the remainder were graded as normal. The portions of the intracranial vessels near the skull base and especially the paracavernous and supraclinoid segments of the internal carotid arteries were areas of frequent over- and underestimation of stenosis due to the presence of dephasing artifacts. In patients with stenosis or occlusion, MR angiography also provided information regarding the presence of collateral flow in the circle of Willis. When used in conjunction with MR imaging of the brain and MR angiography of the extracranial carotid arteries, intracranial MR angiography allows a more complete evaluation of the patient with symptoms of cerebral ischemia or infarction.

Recent developments have allowed the state of the art in acoustic microscopy to progress to the point where acoustic wavelengths equal to and even shorter than visible light wavelengths are now employed. Examination of samples from biology, materials science and integrated circuit technology has revealed several areas of application. Through the use of cryogenic liquids as an acoustic coupling medium very high resolution has been attained and still better resolution, far surpassing the optical microscope, is expected.