Localization of spinal dural arteriovenous fistulas from the spatial relationships of perimedullary vessels on standard MRI.

OBJECTIVE: The goal in this study was to explore the spatial relationship of perimedullary vessels visualized on MRI to localize the side and the site of spinal dural arteriovenous fistula (SDAVF). METHODS: A retrospective analysis of 30 consecutive patients diagnosed with SDAVF on MRI was undertaken. Two experienced reviewers blinded to all reports and angiographic images analyzed T2-weighted as well as postcontrast T1-weighted sequences. A focal prominent zone of perimedullary vessels with lateralization to one side in the thecal space was evaluated to locate the side and the site of the fistula. Spinal digital subtraction angiography served as the gold standard technique. RESULTS: Good interrater agreement (κ = 0.77) was shown for the diagnosis of SDAVF with perimedullary vessels on T2-weighted MRI. Flow voids on T2-weighted MRI demonstrated a sensitivity of 1.0 (95% CI 1.0-1.0) and an accuracy of 0.87 (95% CI 0.79-0.95) to identify the presence of fistula. The flow voids on T2-weighted MRI also demonstrated 0.88 (95% CI 0.71-1.03) sensitivity and 0.81 (95% CI 0.70-0.92) accuracy to identify the side of SDAVF. Furthermore, flow voids on T2-weighted MRI showed 0.87 (95% CI 0.71-1.03) sensitivity and 0.87 (95% CI 0.79-0.95) accuracy to identify the site of SDAVF within 3 vertebral levels above or below the actual site. Area under the receiver operating characteristic curve demonstrated significant results (0.87 [95% CI 0.73-1.0]; p < 0.001) for flow voids on T2-weighted MRI to identify the site of shunts within 3 vertebral levels in the cranial or caudal direction. CONCLUSIONS: Spatial distribution of perimedullary vessels observed on standard MRI show promise to locate the side and the site of fistula in patients with SDAVF.

Variation in Carotid Artery Stenosis Measurements Among Facilities Seeking Carotid Stenting Facility Accreditation.

BACKGROUND: Based on the inclusion criteria of clinical trials, the degree of cervical carotid artery stenosis is often used as an indication for stent placement in the setting of extracranial carotid atherosclerotic disease. However, the rigor and consistency with which stenosis is measured outside of clinical trials are unclear. In an agreement study using a cross-sectional sample, we compared the percent stenosis as measured by real-world physician operators to that measured by independent expert reviewers. METHODS: As part of the carotid stenting facility accreditation review, images were obtained from 68 cases of patients who underwent carotid stent placement. Data collected included demographics, stroke severity measures, and the documented degree of stenosis, termed operator-reported stenosis (ORS), by 34 operators from 14 clinical sites. The ORS was compared with reviewer-measured stenosis (RMS) as assessed by 5 clinicians experienced in treating carotid artery disease. RESULTS: The median ORS was 90.0% (interquartile range, 80.0%-90.0%) versus a median RMS of 61.1% (interquartile range, 49.8%-73.6%), with a median difference of 21.8% (interquartile range, 13.7%-34.4%), P<0.001. The median difference in ORS and RMS for asymptomatic versus symptomatic patients was not statistically different (24.6% versus 19.6%; P=0.406). The median difference between ORS and RMS for facilities granted initial accreditation was smaller compared with facilities whose accreditation was delayed (17.9% versus 25.5%, P=0.035). The intraclass correlation between ORS and RMS was 0.16, indicating poor agreement. If RMS measurements were used, 72% of symptomatic patients and 10% of asymptomatic patients in the population examined would meet the Centers for Medicare and Medicaid Services criteria for stent placement. CONCLUSIONS: Real-world operators tend to overestimate carotid artery stenosis compared with external expert reviewers. Measurements from facilities granted initial accreditation were closer to expert measurements than those from facilities whose accreditation was delayed. Since decisions regarding carotid revascularization are often based on percent stenosis, such measuring discrepancies likely lead to increased procedural utilization.

Detection of cerebral cortical vein thrombosis with high-resolution susceptibility weighted imaging - A comparison with MR venography and standard MR sequences.

PURPOSE: Comparison of the performance of high-resolution susceptibility weighted imaging with standard MR sequences and MR venography to identify cortical vein clots. METHODS: A retrospective review of 51 consecutive cases of cerebral venous thrombosis and 27 controls was performed with independent analysis of all MR sequences. Reference standard was obtained with consensus in a separate session by reviewing all MR sequences together. RESULTS: Cortical vein clots were observed in 30 cases including 9 males and 21 females in the age range of 1 month to 70 years (Mean 34.9 ± 20.2 years). Sensitivity, specificity, negative predictive value, positive predictive value and accuracy of susceptibility weighted imaging for the identification of cortical vein clots were 0.93, 1.0, 1.0, 0.96 and 0.97 respectively. For all other sequences, sensitivity ranged from 0.06 to 0.39 and accuracy from 0.60 to 0.73. Combination of all sequences yielded a value of 1.0 for sensitivity, specificity, positive predictive value, negative predictive value and accuracy for the detection of cortical vein clots. Significant result for area under the receiver operating curve was observed only for SWI with a value of 0.91 (p - .000). CONCLUSION: Susceptibility weighted imaging demonstrates the best sensitivity and accuracy among standard MR sequences including MR venography for the detection of early stage cortical vein clots. However, it needs to be interpreted in combination with other MR sequences for the most accurate evaluation of cortical vein clots.

High-resolution susceptibility-weighted imaging of clots in cerebral venous thrombosis.

PURPOSE: To distinguish cerebral venous clots from patent dural sinuses, cortical veins, and calvarium on high-resolution susceptibility-weighted imaging, since there is lack of a well-designed study in the literature. METHODS: A retrospective review of 51 consecutive cases and 27 controls was performed with susceptibility-weighted imaging independently by two investigators. MR venography along with MR sequences other than the susceptibility-weighted imaging served as the reference standard. RESULTS: There were 29 males and 49 females in the age range of 1 month to 70 years (mean 27 ± 19.8 years). Substantial (k 0.84 to 1.0) to good (k 0.60 to 0.75) inter-rater agreement was observed on the magnitude images for the demonstration of clots in all venous segments, excluding left sigmoid sinus, jugular bulb, and internal jugular vein (k 0.43 to 0.56). Comparatively magnitude images demonstrated better sensitivity (0.83 (0.54-1.13) to 1.0), specificity (0.92 (0.85-0.99) to 1.0), and negative predictive value (0.98 (0.94-1.02) to 1.0) for the detection of clots across all venous segments. Magnitude images showed positive predictive value ranging from 0.83 (0.66-1.0) to 1.0 for clots anywhere from the anterior aspect of superior sagittal sinus to bilateral transverse sinuses. For the detection of clots from bilateral sigmoid sinuses to internal jugular veins, magnitude images showed relatively better positive predictive value ranging from 0.57 (0.20-0.94) to 0.75 (0.45-1.06) in comparison to the processed magnitude and minimum intensity pixel images. CONCLUSION: Susceptibility-weighted imaging can successfully distinguish majority of clots from patent dural sinuses, cortical veins, and calvarium with excellent inter-rater agreements.

Magnetic Resonance Angiography After Flow Diversion: The Use of Complementary Magnetic Resonance Angiography Techniques to Monitor Aneurysm Occlusion and Device and Arterial Branch Patency After Flow Diverter Placement.

BACKGROUND: Few studies have evaluated flow diversion with magnetic resonance angiography (MRA). Studies have shown better success of MRA in assessing the aneurysm response, but limited success in assessing stent patency. The patency of arterial branches on MRA remains to be explored. METHODS: Retrospective evaluation of 31 consecutive cases of carotid aneurysms treated with flow diversion was performed with noncontrast time-of-flight (TOF), contrast-enhanced TOF, and cine MRA (time-resolved angiography with interleaved stochastic trajectories) independently by 2 investigators for aneurysm occlusion, stent patency, and arterial branch patency. Digital subtraction angiography served as the gold standard technique. RESULTS: Patients were 6 men and 25 women with a mean ± SD age of 57.8 ± 12.27 years (range, 32-79 years). Stent patency, aneurysm occlusion, and branch patency mostly revealed substantial to perfect interobserver agreement (κ >0.60). Sensitivity, specificity, positive predictive value, and negative predictive value for stent patency on raw data images of TOF were 0.50, 0.86, 0.20, and 0.96 and on contrast-enhanced TOF were 1.0, 0.93, 0.50, and 1.0. Ranges for aneurysm response on the 3 MRA scans were 0.78-0.89 for sensitivity, 0.54-0.92 for specificity, 0.73-0.93 for positive predictive value, and 0.78-0.86 for negative predictive value. Ranges for arterial branch patency among the 3 MRA scans were 0.87-0.96 for sensitivity, 0.50-1.0 for specificity, 0.90-1.0 for positive predictive value, and 0.33-0.80 for negative predictive value. CONCLUSIONS: Aneurysm occlusion, stent patency, and arterial branch patency in flow diversion can be successfully evaluated with the combination of 3 MRA techniques.

Risk Factors Associated with ICU-Specific Care in Patients Undergoing Endovascular Treatment of Unruptured Intracranial Aneurysms.

BACKGROUND: Multiple studies suggest routine postoperative intensive care unit (ICUs) stays in presumed high-risk neurosurgical procedures may be unnecessary. Our objective was to evaluate the risk factors associated with ICU-specific needs in patients undergoing elective endovascular treatment of unruptured intracranial aneurysms. METHODS: A retrospective review of consecutive patients undergoing elective endovascular treatment of unruptured aneurysms was performed between January 2010 and January 2020 in a single academic medical center. Patient demographic information, aneurysm and treatment characteristics, intraoperative and postoperative complications, as well as ICU-specific needs, were abstracted. The primary outcome was ICU-specific needs. RESULTS: A total of 382 patient encounters in 344 unique patients were abstracted. 13.6% (52 of 382) of patient encounters had an ICU-specific need. Multivariate analysis revealed that age [adjusted odds ratio (OR) 1.04, 95% confidence interval (CI) 1.01-1.07, p = 0.03], procedure duration greater 200 min (adjusted OR 2.75, 95% CI 1.34-5.88, p = 0.007), and any intraoperative complication (adjusted OR 20.41, CI 7.97-56.57, p < 0.001) were independent predictors of postoperative ICU-specific needs. The majority of ICU-specific needs (94%, 49 of 52) occurred within 6 h of surgery. CONCLUSIONS: Our results show that age, procedure duration greater than or equal to 200 min, and intraoperative complication were independent predictors of postoperative ICU-specific needs in patients presenting for elective endovascular treatment of unruptured intracranial aneurysms. The majority of ICU-specific needs and associated complications occurred in the immediate postoperative period. This data can be used to help decide the appropriate postoperative level of care in this patient population.

Quantifying disruption of workflow by phone calls to the neuroradiology reading room.

INTRODUCTION: The purpose of this study was to understand the source and the reason for the phone calls to our neuroradiology suit and to quantify the size of the problem in terms of duration of individual and aggregated calls. MATERIALS AND METHODS: Observation of the neuroradiology reading room for the entire duration of the working hours over three non-consecutive days was performed, and included telephone calls start time, end time and calls duration for incoming telephone calls. After each phone call the recipients were queried on the details of the phone call; the origin of the call, the reason for the call and the response. RESULTS: The average total number of minutes (min) spent on the phone each day was 64 min per working day with a total of 39 phone calls per day and 4.4 per hour on average. The trainees answered 71% of the phone calls with additional intervention by attending in 13% of phone calls. The most common source of phone calls was from either the MRI/CT technicians (48%), followed by providers (20%) and returning pages (18%). CONCLUSION: Cumulative time spent on the phone by neuroradiologists in the reading room ended up in more than an hour per working day, while trainees were taking the majority of phone calls. Most phone calls originated from technicians, hence, requiring specific solutions to mitigate this kind of interruption.

A prospective, randomized, multicenter study of intraosseous basivertebral nerve ablation for the treatment of chronic low back pain.

BACKGROUND CONTEXT: Current literature suggests that degenerated or damaged vertebral endplates are a significant cause of chronic low back pain (LBP) that is not adequately addressed by standard care. Prior 2-year data from the treatment arm of a sham-controlled randomized controlled trial (RCT) showed maintenance of clinical improvements at 2 years following radiofrequency (RF) ablation of the basivertebral nerve (BVN). PURPOSE: The purpose of this RCT was to compare the effectiveness of intraosseous RF ablation of the BVN to standard care for the treatment of chronic LBP in a specific subgroup of patients suspected to have vertebrogenic related symptomatology. STUDY DESIGN/SETTING: A prospective, parallel, open label RCT was conducted at 20 U.S. sites. PATIENT SAMPLE: A total of 140 patients with chronic LBP of at least 6 months duration, with Modic Type 1 or 2 vertebral endplate changes between L3 and S1, were randomized 1:1 to undergo either RF ablation of the BVN or continue standard care. OUTCOME MEASURES: Oswestry Disability Index (ODI) was collected at baseline, 3, 6, 9, and 12-months postprocedure. Secondary outcome measures included a 10-point Visual Analog Scale (VAS) for LBP, ODI and VAS responder rates, SF-36, and EQ-5D-5L. The primary endpoint was a between-arm comparison of the mean change in ODI from baseline to 3 months post-treatment. METHODS: Patients were randomized 1:1 to receive RF ablation or to continue standard care. Self-reported patient outcomes were collected using validated questionnaires at each study visit. An interim analysis to assess for superiority was prespecified and overseen by an independent data management committee when a minimum of 60% of patients had completed their 3-month primary endpoint visit. RESULTS: The interim analysis showed clear statistical superiority (p<.001) for all primary and secondary patient-reported outcome measures in the RF ablation arm compared with the standard care arm. This resulted in a data management committee recommendation to halt enrollment in the study and offer early cross-over to the control arm. These results are comprised of the outcomes of the 104 patients included in the intent-to-treat analysis of the 3-month primary endpoint, which included 51 patients in the RF ablation arm and 53 patients in the standard care arm. Baseline ODI was 46.1, VAS was 6.67, and mean age was 50 years. The percentage of patients with LBP symptoms ≥5 years was 67.3%. Comparing the RF ablation arm to the standard care arm, the mean changes in ODI at 3 months were -25.3 points versus -4.4 points, respectively, resulting in an adjusted difference of 20.9 points (p<.001). Mean changes in VAS were -3.46 versus -1.02, respectively, an adjusted difference of 2.44 cm (p<.001). In the RF ablation arm, 74.5% of patients achieved a ≥10-point improvement in ODI, compared with 32.7% in the standard care arm (p<0.001). CONCLUSIONS: Minimally invasive RF ablation of the BVN led to significant improvement of pain and function at 3-months in patients with chronic vertebrogenic related LBP.

Neurophysiological Monitoring During Arteriovenous Malformation Embolization.

BACKGROUND: Neurophysiological monitoring (NPM) is frequently performed during arteriovenous malformation (AVM) embolization. However, the ability of NPM to predict neurological deficits or improve surgical decision making in this setting has not been studied. OBJECTIVE: To review our use of NPM during AVM embolization to better define its utility. METHODS: We retrospectively examined AVM embolization cases from 2004 to 2017. We recorded patient and AVM characteristics as well as outcomes. We then reviewed NPM results from each case, including somatosensory evoked potentials and electroencephalogram. Our primary outcome was postoperative neurological deficit, and secondary outcomes were discharge and 30-d modified Rankin Score (mRS). RESULTS: There were 173 embolizations in 74 patients. Mean patient age was 40 yr. There were 8 (5%) transient and 2 (1.3%) permanent neurological complications. Among those with neurological complications, 3 had NPM changes during the operation (positive predictive value [PPV] = 50%). This improved to 67% for permanent NPM change. Three patients had NPM changes but did not suffer clinical deficits postoperatively (negative predictive value = 90%). The predictive value of the test was improved for discharge but not 30-d mRS, and the test performance improved dramatically with increased pretest probabilities (likelihood ratio [LR](+) = 14.5, LR(-) = 0.715). CONCLUSION: We present a large series of AVM embolization operations performed with NPM. The PPV of NPM changes was moderate but improved dramatically with increased pretest probabilities. The rate of permanent neurological complications was among the lowest reported in the literature, suggesting NPM may lead to improved intraoperative decision making.

A Comparison of Magnetic Resonance Angiography Techniques for the Evaluation of Intracranial Aneurysms Treated With Stent-assisted Coil Embolization.

AIM: To identify the effective magnetic resonance angiography (MRA) technique to monitor intracranial aneurysms treated with stent-assisted coiling. MATERIALS AND METHODS: Retrospective analysis of various MRA techniques was performed in 42 patients. Three neuroradiologists independently compared non-contrast time of flight (ncTOF) MRA of the head, contrast-enhanced time of flight (cTOF) MRA of the head and dynamic contrast-enhanced MRA (CEMRA) of the head and neck or of the head. Digital subtraction angiography (DSA) was available for comparison in 32 cases. Inter-rater agreement (kappa statistic) was assessed. RESULTS: Artifactual in-stent severe stenosis or flow gap was identified by ncTOF MRA in 23 of 42 cases (55%) and by cTOF MRA in 23 of 38 cases (60%). DSA excluded in-stent stenosis or occlusion in all 32 cases. No difference was noted between ncTOF and cTOF in the demonstration of neck remnants or residual aneurysms in three cases each. CEMRA of the head and neck or of the head was rated superior to ncTOF and cTOF MRA by all three investigators in seven out of eight cases. In one case, all three techniques demonstrated signifcant artifacts due to double stent placement during coiling. The kappa statistic revealed 0.8 agreement between investigators. CONCLUSIONS: In the assessment of stent-assisted coiling of intracranial aneurysm, both ncTOF and cTOF MRA show similar results. CEMRA tends to show better flow signals in stent and residual aneurysm.

Fluoroscopically-guided epidural blood patch for spontaneous intracranial hypotension.

We present three patients with spontaneous intracranial hypotension who failed conservative treatment and were treated with image-guided epidural blood patch close to the cerebrospinal fluid (CSF) leak site. Each patient achieved significant long-term improvement of clinical symptoms and CSF leak related image findings.

Onyx-HD 500 Embolization of a Traumatic Internal Carotid Artery Pseudoaneurysm after Transsphenoidal Surgery.

BACKGROUND AND PURPOSE: Traumatic intracranial pseudoaneurysms present a challenge for treatment. Traditionally these lesions have required a deconstructive approach consisting of vessel sacrifice since their fragile nature often makes direct microsurgical repair or coil embolization hazardous. As a high-viscosity liquid embolic agent that results in immediate, vessel sparing aneurysm occlusion, Onyx-HD 500 represents a uniquely efficacious tool for this clinical situation. CASE SUMMARY: We report the case of a 56-year-old right-handed gentleman who suffered a vascular injury to the ICA during revision transsphenoidal surgery for a recurrent pituitary macroadenoma. The patient was initially treated with nasal packing, but after recurrent episodes of epistaxis and a CT angiogram demonstrating a large traumatic ICA pseudoaneurysm, the patient was referred for invasive treatment. Given the presumed fragility of the lesion, embolization with Onyx-HD 500 was chosen in order to safely achieve immediate aneurysm occlusion without the need for vessel sacrifice. After an early recurrence due to incomplete initial embolization, the patient went on to complete occlusion without further hemorrhage. CONCLUSION: This case illustrates the utility of a high-viscosity liquid embolic agent in providing immediate protection from rehemorrhage by occluding a large ruptured pseudoaneurysm of the proximal intracranial ICA, while sparing the parent artery.

Spontaneous thrombosis of developmental venous anomaly (DVA) with venous infarct and acute cerebellar ataxia.

Developmental venous anomaly (DVA), formally known as venous angioma, is a congenital anatomic variant of the venous drainage of the brain. Although they typically have a benign clinical course and a low symptomatic rate, thrombosis of a drainage vein may occur, leading to potentially debilitating complications. We report a unique case of spontaneous thrombosis of a posterior fossa developmental venous anomaly with cerebellar infarct in a 61-year-old man who presented with acute onset cerebellar ataxia. DVA thrombosis was well-depicted on CT and MR studies. Patient was put on anticoagulant therapy and complete recanalization was seen on follow-up imaging.

Sensitivity of 3D Gradient Recalled Echo Susceptibility-Weighted Imaging Technique Compared to Computed Tomography Angiography for Detection of Middle Cerebral Artery Thrombus in Acute Stroke.

We aimed at comparing the sensitivity of magnetic resonance (MR) susceptibility-weighted imaging (SWI) with computed tomography angiography (CTA) in the detection of middle cerebral artery (MCA) thrombus in acute stroke. Seventy-nine patients with acute MCA stroke was selected using our search engine software; only the ones showing restricted diffusion in the MCA territory on diffusion-weighted images were included. We finally selected 35 patients who had done both MRI (including SWI) and CTA. Twenty random subjects with completely normal MRI (including SWI) exam were selected as control. Two neuroradiologists (blinded to the presence or absence of stroke) reviewed the SW images and then compared the findings with CT angiogram (in patients with stroke). The number of MCA segments showing thrombus in each patient was tabulated to estimate the thrombus burden. Thrombus was detected on SWI in one or more MCA segments in 30 out of 35 patients, on the first review. Of the 30, SWI showed thrombus in more than one MCA segments in 7 patients. CTA depicted branch occlusion in 31 cases. Thrombus was seen on both SWI and CTA in 28 patients. Thrombus was noted in two patients on SWI only, with no corresponding abnormality seen on CTA. Two patients with acute MCA showed no vascular occlusion or thrombus on either CTA or SWI. Only two case of false-positive thrombus was reported in normal control subjects. Susceptibility-weighted images had sensitivity and specificity of 86% and 90% respectively, with positive predictive value 94%. Sensitivity was 86% for SWI, compared with 89% for CTA, and this difference was statistically insignificant (P>0.05). Of all the positive cases on CTA (31) corresponding thrombus was seen on SWI in 90% of subjects (28 of 31). Susceptibility-weighted imaging has high sensitivity for detection of thrombus in acute MCA stroke. Moreover, SWI is a powerful technique for estimation of thrombus burden, which can be challenging on CTA.

Human botfly (Dermatobia hominis) larva in a child's scalp mimicking osteomyelitis.

Furuncular myiasis caused by Dermatobia hominis is endemic throughout Central and South America. However, because of widespread travel, furuncular myiasis has become more common in North America. Misdiagnosis and mismanagement can occur owing to limited awareness of the condition outside endemic areas. We report a case of furuncular myiasis in an immigrant from El Salvador with magnetic resonance imaging findings. The case is unique because neuroimaging was obtained upon the clinical suspicion of calvarial osteomyelitis. Parasitic infestation should be included in the differential diagnosis of a new skin lesion in patients who have traveled to endemic areas.

Brachial artery approach for endovascular treatment of posterior circulation intracranial vascular disease: technique and application in 5 cases.

Although the transbrachial artery approach has been well described as an alternative for percutaneous coronary interventions and diagnostic cerebral arteriography, little has been reported regarding the use of this technique for therapeutic neuroendovascular procedures. We highlight the technical applications of this technique during 5 procedures. Three women (age 68, 69, and 83 years) and 1 man (age 79 years) were treated using brachial artery access. Two of the women with complex posterior circulation aneurysms were treated with stent-assisted coil embolization. The third woman presented with a symptomatic occlusion of the basilar artery and underwent intra-arterial thrombolysis and angioplasty, followed at a later date by a second intra-arterial thrombolysis procedure. The male patient presented with recurrent, intractable posterior circulation ischemic events and underwent balloon angioplasty and stenting of a high-grade stenosis of the right vertebral artery. All patients had failed treatment via a transfemoral route and demonstrated significant thoracoaortic and/or iliofemoral tortuosity. Appropriate intracranial vascular access was achieved in all patients, and there were no intraprocedural complications. We conclude that a transbrachial approach may be successfully used for a variety of therapeutic neuroendovascular interventions when a transfemoral route is not available.

Temporary test occlusion of distal middle cerebral artery using GDC coil.

The treatment of small distal intracranial aneurysms often requires parent vessel occlusion. However, this may be particularly challenging in patients in which the parent vessel serves eloquent brain. Superselective amytal testing is often conducted in these cases, but may prove unreliable or inconclusive. In order to more specifically assess the functional significance of the parent vessel in this patient with a distal left middle cerebral artery pseudoaneurysm who had failed superselective amytal testing, we used a Guglielmi Detachable coil to perform a temporary test occlusion. Testing was performed with the patient awake and examinable, and after no neurological changes were noted, the vessel was permanently occluded, successfully treating the aneurysm. To our knowledge, this is the first report to describe this unique method for assessing a parent vessel that previously had been thought to supply eloquent brain during amytal testing.

Results using a self-expanding stent alone in the treatment of severe symptomatic carotid bifurcation stenosis.

OBJECT: Conventional endovascular therapy for carotid stenosis involves placement of an embolic protection device followed by stent insertion and angioplasty. A simpler approach may be placement of a stent alone. The authors determined how often this approach could be used to treat patients with carotid stenosis, and assessed which factors would preclude this approach. METHODS: Over a period of 6 years, 97 patients with symptomatic carotid stenosis were treated with the intention of using a "stent-only" approach. Arteries in 77 patients (79%) were treated with stents alone, 13 required preinsertion balloon dilation, 6 postinsertion dilation, and 1 both pre- and postinsertion dilation. RESULTS: The mean stenosis according to North American Symptomatic Carotid Endarterectomy Trial criteria was reduced from 82 to 40% in the stent-only group and from 89 to 37% in the stent and balloon angioplasty group. The 30-day stroke and death rate was 7.2%. Patients were followed for a mean of 15 months. In the stent-alone group, the mean preoperative Doppler peak systolic velocity (PSV) was 409 cm/second, with an internal carotid artery/common carotid artery (ICA/CCA) ratio of 7.2. At follow-up review, the PSV decreased to 153 cm/second and the ICA/CCA ratio to 2.1. In the angioplasty group the mean preoperative PSV was 496 cm/second and the ICA/CCA ratio was 9.2, decreasing to 163 cm/second and 2, respectfully, at follow-up evaluation. Restenosis occurred in 12.8% of patients at 6 months and in 15.9% at 1 year. One stroke occurred during the follow-up period in each group. Using multivariable analysis, factors precluding the "stent-only" approach were as follows: severity of stenosis, circumferential calcification, and no history of hyperlipidemia. CONCLUSIONS: Balloons may not be required to treat all patients with carotid stenosis. A stent alone was feasible in 79% of patients, and 79% of patients were alive and free from ipsilateral stroke or restenosis at 1 year. Restenosis rates with this approach are higher than with conventional angioplasty and stent insertion. Carotid arteries with very severe stenoses (> 90%) and circumferential calcification may be more successfully treated with angioplasty combined with stent placement.

Termination of the normal conus medullaris in children: a whole-spine magnetic resonance imaging study.

OBJECT: The mean level of the conus medullaris (CM) has been estimated to lie opposite the L1/2 disc space in several previous studies using ultrasound, CT myelography, and magnetic resonance (MR) imaging, but these studies have been limited in examining only the lumbar spine and including patients being evaluated for back pain and sciatica (creating a selection bias). Moreover, significant variability was found in the termination of the CM, with a small subset of subjects having a CM as low as the mid-body of L4. The authors sought to determine the normal level of the CM and its variability. METHODS: Children with brain or spinal cord tumors who underwent whole-spine surveillance MR imaging were identified retrospectively. The level of the CM was identified in each subject by counting down from C1. Vertebral anomalies, such as lumbarized S1, sacralized L5, or fewer rib-bearing segments, and the presence of fatty filum were noted. RESULTS: Findings regarding the level of termination of the CM were tightly grouped; the average was at the lower third of L1 and the mode of the distribution was at the L1/2 disc space, with very little variation. No CM ended below the mid-body of L2. The level of the CM was not significantly different among individuals with lumbarized or sacralized vertebrae or 11 rib-bearing segments. CONCLUSIONS: The CM terminates most commonly at the L1-2 disc space and in the absence of tethering, the CM virtually never ends below the mid-body of L2. A CM that appears more caudal on neuroimages should be considered tethered.

Comparison of maximum intensity projection and digitally reconstructed radiographic projection for carotid artery stenosis measurement.

Digital subtraction angiography is being supplanted by three-dimensional imaging techniques in many clinical applications, leading to extensive use of maximum intensity projection (MIP) images to depict volumetric vascular data. The MIP algorithm produces intensity profiles that are different than conventional angiograms, and can also increase the vessel-to-tissue contrast-to-noise ratio. We evaluated the effect of the MIP algorithm in a clinical application where quantitative vessel measurement is important: internal carotid artery stenosis grading. Three-dimensional computed rotational angiography (CRA) was performed on 26 consecutive symptomatic patients to verify an internal carotid artery stenosis originally found using duplex ultrasound. These volumes of data were visualized using two different postprocessing projection techniques: MIP and digitally reconstructed radiographic (DRR) projection. A DRR is a radiographic image simulating a conventional digitally subtracted angiogram, but it is derived computationally from the same CRA dataset as the MIP. By visualizing a single volume with two different projection techniques, the postprocessing effect of the MIP algorithm is isolated. Vessel measurements were made, according to the NASCET guidelines, and percentage stenosis grades were calculated. The paired t-test was used to determine if the measurement difference between the two techniques was statistically significant. The CRA technique provided an isotropic voxel spacing of 0.38 mm. The MIPs and DRRs had a mean signal-difference-to-noise-ratio of 30:1 and 26:1, respectively. Vessel measurements from MIPs were, on average, 0.17 mm larger than those from DRRs (P < 0.0001). The NASCET-type stenosis grades tended to be underestimated on average by 2.4% with the MIP algorithm, although this was not statistically significant (P=0.09). The mean interobserver variability (standard deviation) of both the MIP and DRR images was 0.35 mm. It was concluded that the MIP algorithm slightly increased the apparent dimensions of the arteries, when applied to these intra-arterial CRA images. This subpixel increase was smaller than both the voxel size and interobserver variability, and was therefore not clinically relevant.