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Background and Purpose: CSF leaks of the skull base and spine share a common process of CSF volume loss, and yet only the latter has been associated with spontaneous intracranial hypotension (SIH). Despite published claims that only spinal leaks cause SIH, no prior studies have evaluated brain MR imaging in patients with skull base leaks for findings associated with SIH, such as dural enhancement. The purpose of our study was to use a validated brain MR imaging scoring system to evaluate patients with skull base CSF leaks for findings associated with SIH., Materials and Methods: We included patients with confirmed skull base CSF leaks and contrast-enhanced preoperative brain MRI. The preoperative MR images were reviewed for findings associated with SIH by using the Bern score. Patient age, presenting symptoms and their duration, and leak site were also recorded., Results: Thirty-one patients with skull base CSF leaks were included. Mean Bern score was 0.9 (range 0-4, standard deviation 1.1), and only 1 patient (3%) had dural enhancement. Mean age was 53 years (range 18-76). Mean symptom duration was 1.3 years, with 22 patients presenting within 1 year of symptom onset. Twenty-three patients (74.2%) had intraoperative confirmation of leak from the middle cranial fossa, involving the temporal bone, while 7 (22.6%) had leaks from the anterior skull base. One patient, who had dural enhancement, had an infratentorial CSF leak along the petrous segment of the internal carotid artery., Conclusions: Our study provides further evidence that skull base and spinal CSF leaks represent distinct pathophysiologies and present with different brain MRI findings., (© 2024 by American Journal of Neuroradiology.)

Background and Purpose: Diagnosing spontaneous intracranial hypotension and associated CSF leaks can be challenging, and additional supportive imaging findings would be useful to direct further evaluation. This retrospective study evaluated whether there was a difference in the prevalence of calvarial hyperostosis in a cohort of patients with spontaneous intracranial hypotension compared with an age- and sex-matched control population., Materials and Methods: Cross-sectional imaging (CT of the head or brain MR imaging examinations) for 166 patients with spontaneous intracranial hypotension and 321 matched controls was assessed by neuroradiologists blinded to the patient's clinical status. The readers qualitatively evaluated the presence of diffuse or layered calvarial hyperostosis and measured calvarial thickness in the axial and coronal planes., Results: A significant difference in the frequency of layered hyperostosis (31.9%, 53/166 subjects versus 5.0%, 16/321 controls, P  < .001, OR = 11.58) as well as the frequency of overall (layered and diffuse) hyperostosis (38.6%, 64/166 subjects versus 13.2%, 42/321 controls, P  < .001, OR = 4.66) was observed between groups. There was no significant difference in the frequency of diffuse hyperostosis between groups (6.6%, 11/166 subjects versus 8.2%, 26/321 controls, P = .465). A significant difference was also found between groups for calvarial thickness measured in the axial ( P  < .001) and coronal ( P  < .001) planes., Conclusions: Layered calvarial hyperostosis is more prevalent in spontaneous intracranial hypotension compared with the general population and can be used as an additional noninvasive brain imaging marker of spontaneous intracranial hypotension and an underlying spinal CSF leak., (© 2022 by American Journal of Neuroradiology.)

Background and Purpose: There is a general assumption in the cerebrovascular literature that there is an association between carotid artery tortuosity and connective tissues disease; however, this has not been firmly established. The purpose of this study was to determine the prevalence of carotid artery tortuosity in patients with connective tissue diseases relative to matched controls., Materials and Methods: Patients with previous CTA or MRA and a diagnosis of connective tissue diseases were identified and compared with a cohort of age-matched controls. Radiologists blinded to the diagnosis reviewed the images and evaluated the presence of carotid artery tortuosity (including loops, kinks, or coils). Continuous variables were compared using the Student t test, and categoric variables with χ 2 tests., Results: One hundred forty-three patients with connective tissue disease and 143 controls were included in this study. Specific diagnoses included Marfan ( n = 33), nonvascular Ehlers-Danlos ( n = 36), Ehlers-Danlos vascular-type ( n = 32), neurofibromatosis type 1 ( n = 26), and Loeys-Dietz ( n = 16) syndromes. The presence of carotid tortuosity was 44% in connective tissue disease and 16% in controls ( P < .001). Of tortuosity manifestations, coils were most prevalent (23% versus 3%; P < .001). Among the various connective tissue diseases, the rates of any carotid tortuosity were 88% for Marfan syndrome, 63% for Loeys-Dietz syndrome, 42% for neurofibromatosis type 1, and 19% for both vascular- and nonvascular-type Ehlers-Danlos syndrome. The positive predictive value of the combination of aortic aneurysm and carotid tortuosity being associated with connective tissue disease was 95.4%. The specificity was 98.6%., Conclusions: Carotid artery tortuosity is highly associated with connective tissue diseases, particularly Marfan syndrome, Loeys-Dietz syndrome, and neurofibromatosis type 1. Such findings are relevant in risk assessment for vascular complications in connective tissue disease, endovascular treatment planning, and in understanding the pathomechanisms of vascular tortuosity in general., (© 2019 by American Journal of Neuroradiology.)

Background and Purpose: The significance of renal contrast on CT myelography is uncertain. This project examined different patient populations undergoing CT myelography for the presence of renal contrast to determine whether this finding is of diagnostic value in spontaneous intracranial hypotension., Materials and Methods: Four groups of patients were analyzed for renal contrast on CT myelography. The control group underwent CT myelography for reasons other than spontaneous intracranial hypotension ( n = 47). Patients in study group 1 had spontaneous intracranial hypotension but CT myelography negative for dural CSF leak and CSF venous fistula ( n = 83). Patients in study group 2 had spontaneous intracranial hypotension and CT myelography positive for dural CSF leak ( n = 44). Patients in study group 3 had spontaneous intracranial hypotension and CT myelography suggestive of CSF venous fistula due to a hyperdense paraspinal vein ( n = 17, eleven surgically confirmed)., Results: Renal contrast was present on the initial CT myelography in 0/47 patients in the control group, 10/83 patients in group one, 1/44 patients in group 2, and 7/17 patients in group 3. Renal contrast on initial CT myelography in patients with suspected or surgically confirmed CSF venous fistula was significantly more likely than in patients with a dural CSF leak ( P = .0003)., Conclusions: Renal contrast on initial CT myelography was seen only in patients with spontaneous intracranial hypotension. This was more common in confirmed/suspected CSF venous fistulas compared with dural leaks. Early renal contrast in patients with spontaneous intracranial hypotension should prompt scrutiny for a hyperdense paraspinal vein, and, if none is found, potentially advanced diagnostic studies., (© 2019 by American Journal of Neuroradiology.)

Background and Purpose: The role of vertebroplasty in patients with myeloma remains relatively undefined. Accordingly, we sought to better define the efficacy of vertebroplasty for myeloma-associated fractures and determine the effect of procedure timing relative to the initiation of systemic therapy on outcomes and complication rates., Materials and Methods: Clinical, laboratory, and medication data were retrieved for 172 patients with multiple myeloma treated with vertebroplasty since October 2000. Quantitative outcome data (Roland-Morris Disability Questionnaire [scale, 0-24] and the Numeric Rating Scale [0-10] for pain at rest and with activity) were collected immediately pre- and postoperatively and at 1 week, 1 month, 6 months, and 1 year following vertebroplasty. Patients with ≥50% improvement on the Numeric Rating Scale and ≥40% improvement on the Roland-Morris Disability Questionnaire were classified as "responders." Peri- and postoperative complications were also collected., Results: Significant median improvement in the Roland-Morris Disability and rest and activity Numeric Rating Scale scores (15, 2, and 6 points, respectively; P < .0001) persisted at 1 year without significant change from the immediate postoperative scores (P > .36). Patients on systemic therapy at the time of vertebroplasty were more likely to achieve "responder status," compared with patients not on systemic therapy, for the Numeric Rating Scale pain at rest score (P < .01) and the Roland-Morris Disability Questionnaire score (P < .003), with no difference in complication rates (χ 2 = 0.17, P = .68)., Conclusions: Vertebroplasty is an effective therapy for patients with myeloma with symptomatic compression fractures. Favorable outcomes are more likely to be achieved when spinal augmentation is performed after systemic therapy is initiated. Complication rates were not affected by the timing of systemic therapy., (© 2016 by American Journal of Neuroradiology.)

Background and Purpose: We adopted an imaging algorithm in 2011 in which extradural fluid on spinal MR imaging directs dynamic CT myelography. We assessed algorithm compliance and its effectiveness in reducing repeat or unnecessary dynamic CT myelograms., Materials and Methods: CT myelograms for CSF leaks from January 2011 to September 2014 were reviewed. Patients with iatrogenic leaks, traumatic brachial plexus injuries, or prior CT myelography within 2 years were excluded. Completion and results of spinal MR imaging, CT myelographic technique, and the need for repeat CT myelography or unnecessary dynamic CT myelograms were recorded., Results: The algorithm was followed in 102 (79%) of 129 patients. No extradural fluid was detected in 75 (74%), of whom 70 (93%) had no leak, 4 (5%) had a slow leak, and 1 (1%) had a fast leak. Extradural fluid was detected in 27 (26%): 24 (89%) fast leaks, 1 (4%) slow leak, and 2 (7%) with no leaks. When the algorithm was followed, 1 (1%) required repeat CT myelography and 3 (3%) had unnecessary dynamic CT myelograms. The algorithm was breached in 27 (21%) cases, including no pre-CT myelogram MR imaging in 11 (41%), performing conventional CT myelography when extradural fluid was present in 13 (48%), and performing dynamic CT myelography when extradural fluid was absent in 3 (11%). Algorithm breaches resulted in 4 (15%) repeat CT myelograms and 3 (12%) unnecessary dynamic CT myelograms, both higher than with algorithm compliance., Conclusions: Using spinal MR imaging to direct CT myelography resulted in significant reduction in repeat CT myelograms to localize fast leaks with minimal unnecessary dynamic CT myelograms., (© 2016 by American Journal of Neuroradiology.)

Background and Purpose: Imaging features of spine degeneration are common in symptomatic and asymptomatic individuals. We compared the prevalence of MR imaging features of lumbar spine degeneration in adults 50 years of age and younger with and without self-reported low back pain., Materials and Methods: We performed a meta-analysis of studies reporting the prevalence of degenerative lumbar spine MR imaging findings in asymptomatic and symptomatic adults 50 years of age or younger. Symptomatic individuals had axial low back pain with or without radicular symptoms. Two reviewers evaluated each article for the following outcomes: disc bulge, disc degeneration, disc extrusion, disc protrusion, annular fissures, Modic 1 changes, any Modic changes, central canal stenosis, spondylolisthesis, and spondylolysis. The meta-analysis was performed by using a random-effects model., Results: An initial search yielded 280 unique studies. Fourteen (5.0%) met the inclusion criteria (3097 individuals; 1193, 38.6%, asymptomatic; 1904, 61.4%, symptomatic). Imaging findings with a higher prevalence in symptomatic individuals 50 years of age or younger included disc bulge (OR, 7.54; 95% CI, 1.28-44.56; P = .03), spondylolysis (OR, 5.06; 95% CI, 1.65-15.53; P < .01), disc extrusion (OR, 4.38; 95% CI, 1.98-9.68; P < .01), Modic 1 changes (OR, 4.01; 95% CI, 1.10-14.55; P = .04), disc protrusion (OR, 2.65; 95% CI, 1.52-4.62; P < .01), and disc degeneration (OR, 2.24; 95% CI, 1.21-4.15, P = .01). Imaging findings not associated with low back pain included any Modic change (OR, 1.62; 95% CI, 0.48-5.41, P = .43), central canal stenosis (OR, 20.58; 95% CI, 0.05-798.77; P = .32), high-intensity zone (OR = 2.10; 95% CI, 0.73-6.02; P = .17), annular fissures (OR = 1.79; 95% CI, 0.97-3.31; P = .06), and spondylolisthesis (OR = 1.59; 95% CI, 0.78-3.24; P = .20)., Conclusions: Meta-analysis demonstrates that MR imaging evidence of disc bulge, degeneration, extrusion, protrusion, Modic 1 changes, and spondylolysis are more prevalent in adults 50 years of age or younger with back pain compared with asymptomatic individuals., (© 2015 by American Journal of Neuroradiology.)

Background and Purpose: Degenerative changes are commonly found in spine imaging but often occur in pain-free individuals as well as those with back pain. We sought to estimate the prevalence, by age, of common degenerative spine conditions by performing a systematic review studying the prevalence of spine degeneration on imaging in asymptomatic individuals., Materials and Methods: We performed a systematic review of articles reporting the prevalence of imaging findings (CT or MR imaging) in asymptomatic individuals from published English literature through April 2014. Two reviewers evaluated each manuscript. We selected age groupings by decade (20, 30, 40, 50, 60, 70, 80 years), determining age-specific prevalence estimates. For each imaging finding, we fit a generalized linear mixed-effects model for the age-specific prevalence estimate clustering in the study, adjusting for the midpoint of the reported age interval., Results: Thirty-three articles reporting imaging findings for 3110 asymptomatic individuals met our study inclusion criteria. The prevalence of disk degeneration in asymptomatic individuals increased from 37% of 20-year-old individuals to 96% of 80-year-old individuals. Disk bulge prevalence increased from 30% of those 20 years of age to 84% of those 80 years of age. Disk protrusion prevalence increased from 29% of those 20 years of age to 43% of those 80 years of age. The prevalence of annular fissure increased from 19% of those 20 years of age to 29% of those 80 years of age., Conclusions: Imaging findings of spine degeneration are present in high proportions of asymptomatic individuals, increasing with age. Many imaging-based degenerative features are likely part of normal aging and unassociated with pain. These imaging findings must be interpreted in the context of the patient's clinical condition., (© 2015 by American Journal of Neuroradiology.)

Background and Purpose: CT is a ubiquitous, efficient, and cost-effective method to evaluate pediatric ventricular size, particularly in patients with CSF shunt diversion who often need emergent imaging. We therefore sought to determine the minimum dose output or CT dose index required to produce clinically acceptable examinations., Materials and Methods: Using a validated noise insertion method and CT projection data from 22 patients, standard pediatric head CT images were reconstructed with weighted filtered back-projection and sinogram-affirmed iterative reconstruction corresponding to routine, 25%, and 10% dose. Reconstructed images were then evaluated by 3 neuroradiologists (blinded to dose and reconstruction method) for ventricular size, diagnostic confidence, image quality, evidence of hemorrhage, and shunt tip location, and compared with the reference standard., Results: There was no significant difference in the ventricular size ranking, and the sensitivity for moderate to severe hydrocephalus was 100%. There was no significant difference between the full-dose level and the ventricular size rankings at the 25% or the 10% dose level for either reconstruction kernel (P > .979). Diagnostic confidence was maintained across doses and kernel. Hemorrhage was more difficult to identify as image quality degraded as dose decreased but was still seen in a majority of cases. Shunts were identified by all readers across all doses and reconstruction methods., Conclusions: CT images having dose reductions of 90% relative to routine head CT examinations provide acceptable image quality to address the specific clinical task of evaluating ventricular size., (© 2014 by American Journal of Neuroradiology.)

Background and Purpose: MRA is widely accepted as a noninvasive diagnostic tool for the detection of intracranial aneurysms, but detection is still a challenging task with rather low detection rates. Our aim was to examine the performance of a computer-aided diagnosis algorithm for detecting intracranial aneurysms on MRA in a clinical setting., Materials and Methods: Aneurysm detectability was evaluated retrospectively in 48 subjects with and without computer-aided diagnosis by 6 readers using a clinical 3D viewing system. Aneurysms ranged from 1.1 to 6.0 mm (mean = 3.12 mm, median = 2.50 mm). We conducted a multireader, multicase, double-crossover design, free-response, observer-performance study on sets of images from different MRA scanners by using DSA as the reference standard. Jackknife alternative free-response operating characteristic curve analysis with the figure of merit was used., Results: For all readers combined, the mean figure of merit improved from 0.655 to 0.759, indicating a change in the figure of merit attributable to computer-aided diagnosis of 0.10 (95% CI, 0.03-0.18), which was statistically significant (F(1,47) = 7.00, P = .011). Five of the 6 radiologists had improved performance with computer-aided diagnosis, primarily due to increased sensitivity., Conclusions: In conditions similar to clinical practice, using computer-aided diagnosis significantly improved radiologists' detection of intracranial DSA-confirmed aneurysms of ≤6 mm., (© 2014 by American Journal of Neuroradiology.)

Background and Purpose: Normative data for CSF OP have previously been established with patients in the LD position. During fluoroscopically guided LP procedures, radiologists frequently obtain these OP measurements with patients prone. In this prospective study, our goal was to determine the variability of OP measurements as a function of patient positioning and to assess whether there is a relationship with patient BMI., Materials and Methods: Consecutive patients reporting for fluoroscopically guided LP or myelography were enrolled. OP was measured with the patient in 3 positions, with the order of the technique randomized: prone with table flat, prone with table tilted until the hub of the needle was at the level of the right atrium, and LD with the needle hub at the level of the spinal canal. The BMI of each patient was calculated. The Wilcoxon signed-rank test and linear regression analysis with bivariate fit of difference were used for analysis., Results: OP measurements with the patient in the prone position were significantly elevated compared with those in the LD position, with mean differences of 2.7 (P<.001) and 1.6 cm H2O, (P=.017) for prone flat and prone tilted, respectively. There was no significant difference in OP measurements for the prone flat versus prone tilted positions (P=.20). There was no correlation between BMI and observed differences (LD-flat: R2=0.00028; LD-tilt: R2=0.00038; prone-tilt: R2=0.00000020)., Conclusions: Measuring OP with the patient in the prone position may result in overestimation of CSF pressure. Table tilt did not significantly impact mean prone OP. Radiologists should specify exact patient positioning when reporting OP measurements.

Background and Purpose: Most studies of HD have been conducted in Asia, particularly Japan. To characterize the MR imaging findings of North American patients with HD, we reviewed neutral and flexion cervical MR imaging examinations performed for possible HD at 3 academic medical centers located in the Southeastern, Southwestern, and Midwestern regions of the United States., Materials and Methods: Three neuroradiologists assessed the MR imaging examinations in a blinded fashion and reached a consensus rating for LOA of the posterior dura to the spine, lower spinal cord atrophy, spinal cord T2 hyperintensity, loss of cervical lordosis, anterior dural shift with flexion, and confidence of imaging diagnosis. Final reference diagnosis was established separately with a retrospective chart review by a neurologist., Results: Twenty-one patients met the criteria for HD, all were North American males and all who reported their race were white. Seventeen patients did not meet the criteria and served as controls. Four imaging attributes, LOA, dural shift with flexion, consensus diagnosis of neutral images, and consensus diagnosis of combined neutral and flexion images were all able to discriminate the group with HD from the group without HD (P < .05 for each). Findings of HD were often present on neutral images, but the addition of flexion images increased diagnostic confidence., Conclusions: MR imaging findings in white North American patients with HD include LOA on neutral images and forward displacement of the dura with flexion. Findings are often present on neutral MR images and, in the appropriate clinical scenario, should prompt flexion MR imaging to evaluate anterior dural shift.

Background and Purpose: Some patients with SIH have fast CSF leaks requiring dynamic CTM for localization; however, patients generally undergo conventional CTM before a dynamic study. Our aim was to determine whether findings on head MR imaging, spine MR imaging, or opening pressure measurements can predict fast spinal CSF leaks., Materials and Methods: A retrospective review was performed on 151 consecutive patients referred for CTM to evaluate for spinal CSF leak. Head MR imaging was evaluated for diffuse dural enhancement and "brain sag," and spine MR imaging for presence of an extradural fluid collection. The opening pressure was recorded. The CTM was scored as no leak, slow leak localized on conventional CTM, or fast leak that required dynamic CTM., Results: Fast CSF leaks were identified in 32 (21%), slow leaks in 36 (24%), and no leak in 83 (55%) of 151 patients on initial CTM. There was significant association between spinal extra-arachnoid fluid on MR imaging and the presence of a fast leak (sensitivity 85%, specificity 79%, P < .0001). There was not significant association between fast leak and findings on head MR imaging (P = .27) or opening pressure (P = .30)., Conclusions: If all patients with spinal extra-arachnoid CSF on MR imaging had been sent directly to dynamic CTM, repeat myelography would have been avoided in most patients with fast leaks (23 of 27; 85%). However, a minority of patients with slow or no leaks would have been converted from conventional to dynamic CTM (16 of 77; 21%). Spinal MR imaging is helpful in premyelographic evaluation of SIH.

Background and Purpose: Localization of spinal CSF leaks in CSF hypovolemia is critical in directing focal therapy. In this retrospective review, our aim was to determine whether GdM was helpful in confirming and localizing spinal CSF leaks in patients in whom no leak was identified on a prior CTM., Materials and Methods: Forty-one symptomatic patients with clinical suspicion of SIH were referred for GdM after undergoing at least 1 CTM between February 2002 and August 2010. A retrospective review of the imaging and electronic medical records was performed on each patient., Results: In 17 of the 41 patients (41%), GdM was performed for follow-up of a previously documented leak at CTM. In the remaining 24 patients (59%), in whom GdM was performed for a suspected CSF leak, which was not identified on CTM, GdM localized the CSF leak in 5 of 24 patients (21%). In 1 of these 5 patients, GdM detected the site of leak despite negative findings on brain MR imaging, spine MR imaging, and CTM of the entire spine. Sixteen of 17 patients with previously identified leaks underwent interval treatment, and leaks were again identified in 12 of 17 (71%)., Conclusions: GdM is a useful technique in the highly select group of patients who have debilitating symptoms of SIH, a high clinical index of suspicion of spinal CSF leak, and no demonstrated leak on conventional CTM. Intrathecal injection of gadolinium contrast remains an off-label use and should be reserved for those patients who fail conventional CTM.

Background and Purpose: Percutaneous polymethylmethacrylate (PMMA) vertebroplasty has become a common procedure for treatment of pain and disability associated with vertebral compression fractures. We reviewed the experience with our first 1000 consecutively treated vertebral compression fractures in an attempt to demonstrate both the short- and long-term safety and efficacy of percutaneous vertebroplasty., Materials and Methods: The first 1000 compression fractures treated by vertebroplasty at our institution were identified from a comprehensive prospectively acquired vertebroplasty data base. All patients treated with vertebroplasty were included, regardless of the underlying pathologic cause. Chart reviews of the procedure notes, imaging studies, clinical visits, and follow-up telephone interviews were performed for each patient. Evaluation at each follow-up time point included pain response (subjective and visual analog pain score), change in mobility, change in pain medication usage, and modified Roland-Morris Disability Questionnaire. Statistical analysis was performed on the pain response and change in the Roland-Morris score at each follow-up time point. Significant procedure-related complications that occurred from the time of the procedure were also specifically extracted from the patients' charts., Results: There was a dramatic improvement in all the evaluated parameters following percutaneous vertebroplasty. The improvement in pain, mobility, medication usage, and Roland-Morris score was noticed immediately after the procedure and persisted through the 2-year follow-up. There was a low rate of complications from the procedure, the most common being rib fractures., Conclusion: According to our results, practitioners can quote a high success rate and low complication rate for vertebroplasty when making treatment recommendations for painful spinal compression fractures.

Background and Purpose: Few reports have documented signal abnormalities within the corpus callosum on MR studies obtained after ventricular decompression in patients with hydrocephalus. Our purpose was to establish the frequency of this finding in shunted patients and attempt to elucidate its cause and clinical significance., Methods: All patients with hydrocephalus shunted between 1989 and 1999 with postoperative MR studies available for review were included in the study group. Imaging analysis consisted of documenting hypointense signal on T1-weighted sagittal images and hyperintense signal on double-echo T2-weighted axial images within the corpus callosum., Results: Characteristic signal abnormalities in the corpus callosum were noted in nine of 161 patients with shunted hydrocephalus studied with MR imaging. All nine patients were asymptomatic in regard to these MR findings. Comparison with preoperative scans and surgical records revealed that all patients with signal changes on postshunt scans had chronic obstructive hydrocephalus at presentation. Preshunt MR images were notable for marked elevation of the corpus callosum, which subsequently descended after ventricular decompression, suggesting that the cause of the signal changes was related to compression of the corpus callosum against the rigid falx., Conclusion: Signal abnormalities within the corpus callosum after ventricular shunting for obstructive hydrocephalus are not uncommon and are probably produced by compression of the corpus callosum against the falx before ventricular decompression. This distinctive appearance should not be mistaken for significant disease. Recognition of this pattern of signal abnormality will help avoid unnecessary intervention.

Purpose: Our objective was to determine whether appropriate criteria could be developed for performing an endarterectomy on the basis of sonographic and MR angiographic findings., Methods: Fifty patients were examined prospectively with sonography, MR angiography, and conventional angiography. All three imaging studies were performed within 2 weeks of one another, and conventional angiography served as the reference standard., Results: All 10 carotid occlusions were detected with sonography and MR angiography. Sonography accurately showed flow in two arteries, and MR angiography showed flow in one of three nearly occluded arteries with extremely slow flow. Multislab three-dimensional time-of-flight MR angiographic sequences underestimated the degree of stenosis in 12 arteries, and in two cases this resulted from high T1 signal within the atherosclerotic plaque. With conventional angiography as the reference standard for 70% to 99% stenosis, sonography had a sensitivity of 96%, a specificity of 91%, and a positive predictive value of 90%, while concordant sonographic findings and the presence of a signal void on multislab 3-D time-of-flight sequences had a sensitivity of 72%, a specificity of 98%, and a positive predictive value of 97%., Conclusion: Endarterectomy performed on the basis of sonographic findings of 70% to 99% stenosis and of a signal void on multislab 3-D time-of-flight MR angiographic sequences is appropriate.

Purpose: To determine the sensitivity of time-of-flight and phase-contrast MR angiography for the detection of intracranial aneurysms., Methods: Sixteen patients with 27 intracranial aneurysms previously identified with conventional angiography and 19 control patients were examined with three-dimensional time-of-flight, three-dimensional phase-contrast MR angiography, and standard MR imaging. Subvolumes of the carotid and posterior circulations, source images, and standard MR images were blindly interpreted by three experienced neuroradiologists., Results: Detection of an aneurysm by a given sequence was defined as at least two of the three blinded readers identifying the aneurysm. The sensitivities of the sequences based on all 27 aneurysms were: transaxial T1, 25.9%; T2, 48.1%; PC, 44.4%; and TF, 55.6%. Two of 3 aneurysms detected with T2 but not MR angiography had adjacent blood products. Five millimeters appeared to be a critical size; the sensitivities for aneurysms greater than or equal to 5 mm were: T1, 37.5%; T2, 62.5%; PC, 75%; and TF, 87.5%., Conclusions: Three-dimensional time-of-flight MR with 512 x 256 matrix is more sensitive than three-dimensional phase-contrast or standard MR imaging for detection of aneurysms. Retrospectively, aneurysms 3 mm or larger can be identified with MR angiography; however, prospectively, 5 mm is the critical size for detection.