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John Huston

Publications and source records attributed to John Huston.

At least 19 recordsLinked to original sources
PubMed2006

MR angiography fusion technique for treatment planning of intracranial arteriovenous malformations.

PURPOSE: To develop an image fusion technique using elliptical centric contrast-enhanced (CE) MR angiography (MRA) and three-dimensional (3D) time-of-flight (TOF) acquisitions for radiosurgery treatment planning of arteriovenous malformations (AVMs). MATERIALS AND METHODS: CE and 3D-TOF MR angiograms with disparate in-plane fields of view (FOVs) were acquired, followed by k-space reformatting to provide equal voxel dimensions. Spatial domain addition was performed to provide a third, fused data volume. Spatial distortion was evaluated on an MRA phantom and provided slice-dependent and global distortion along the three physical dimensions of the MR scanner. In vivo validation was performed on 10 patients with intracranial AVMs prior to their conventional angiogram on the day of gamma knife radiosurgery. RESULTS: Spatial distortion in the phantom within a volume of 14 x 14 x 3.2 cm(3) was less than +/-1 mm (+/-1 standard deviation (SD)) for CE and 3D-TOF data sets. Fused data volumes were successfully generated for all 10 patients. CONCLUSION: Image fusion can be used to obtain high-resolution CE-MRA images of intracranial AVMs while keeping the fiducial markers needed for gamma knife radiosurgery planning. The spatial fidelity of these data is within the tolerance acceptable for daily quality control (QC) purposes and gamma knife treatment planning.

Adult↗
PubMed2006

Imaging artifacts at 3.0T.

Clinical MRI at a field strength of 3.0T is finding increasing use. However, along with the advantages of 3.0T, such as increased SNR, there can be drawbacks, including increased levels of imaging artifacts. Although every imaging artifact observed at 3.0T can also be present at 1.5T, the intensity level is often higher at 3.0T and thus the artifact is more objectionable. This review describes some of the imaging artifacts that are commonly observed with 3.0T imaging, and their root causes. When possible, countermeasures that reduce the artifact level are described.

Artifacts↗
PubMed2006

Undersampled elliptical centric view-order for improved spatial resolution in contrast-enhanced MR angiography.

Although contrast-enhanced MR angiography (CE-MRA) has been successfully developed into a routine clinical imaging technique, there is still need for improved spatial resolution in a given acquisition time. Undersampled projection reconstruction (PR) techniques maintain spatial resolution with reduced scan times, and the elliptical centric (EC) view order provides high quality arterial phase images without venous contamination. In this work, we present a hybrid elliptical centric-projection reconstruction (EC-PR) technique to provide spatial resolution improvement over standard EC in a given time. The k-space sampling was performed by undersampling the periphery of the k(Y)-k(Z) phase encoding plane of an EC view order in a PR like manner. The sampled views were maintained on a rectilinear grid, and thus reconstructed by standard 3DFT. The non-sampled views were compensated either by zero-filling or performing a 2D homodyne reconstruction. Compared to a fully sampled k-space, the EC-PR sequence acquired in the same scan time provides a resolution improvement of about two, as shown by point spread function analysis and phantom experiments. The hypothesis that EC-PR provides improved resolution while retaining diagnostically adequate SNR was tested in 11 CE-MRA studies of the popliteal and carotid arteries and shown to be true (P < 0.03).

Carotid Arteries↗
PubMed2006

Extracranial carotid MR imaging at 3T.

Some controversy exists over the accuracy and optimal parameters for carotid CE MR angiography at 1.5T. Spatial resolution remains more important than does temporal resolution to address the key question of vessel stenosis, based upon a review of the available literature that compares CE MR angiography with DSA. Specifically, CE MR angiograms with 0.9- to 1.2-mm resolution in all three planes before interpolation have a high reported sensitivity and specificity compared with DSA. To achieve this type of spatial resolution, cover the entire course of the carotid arteries from the aortic arch through the skull base, and achieve an absence of venous signal usually requires an elliptic-centric phase encoding CE MR angiogram that lasts for 50 to 60 seconds without the use of parallel imaging techniques. This near-millimeter resolution requires an accurate timing of the gadolinium bolus arrival to maximize intra-arterial SNR and to minimize venous contamination. Parallel imaging techniques can decrease the imaging time, but at a cost of some SNR. Initial experience with eight-channel or higher neurovascular coils at 3T indicates an increase in SNR/CNR compared with 1.5T. This should allow more consistent submillimeter-resolution carotid CE MR angiography with adequate SNR to maintain good IQ in a wide variety of clinical patients. Although a definite, prospective comparison of various CE MR angiography techniques,including a 20- to 30-second scan with 1.2- to 1.4-mm(3) voxel resolution and 50- to 60-second scan with 0.9- to 1.1-mm(3) voxel resolution at 1.5T, as well as 0.5- to 0.6-mm(3) voxel resolution with scan time of 50 to 60 seconds at 3T versus rotational DSA does not exist, the expectation is that the higher resolution and increased SNR that has resulted from 3T carotid CE MR angiography will have high sensitivity and specificity in detecting severe carotid stenosis. The most exciting application of 3T for carotid artery imaging may not be the higher resolution CE MR angiogram, however. Early work has demonstrated the potential of 3T, combined with sensitive surface coils, to depict carotid plaque with sufficient SNR to identify important plaque components consistently in most patients. This could help move MR imaging of the carotid arteries away from a strict evaluation of luminal narrowing to a focused evaluation of plaque morphology. Much work needs to be done. Although there is a growing body of literature to support the contention that plaque morphology is a predictor of subsequent thrombo-embolic disease, the natural history of these various plaque components in a large number of patients needs to be elucidated. If plaque characterization proves to be an independent risk factor that predicts stroke, more aggressive clinical treatment option strategies may be devised for patients who are at the highest risk. Currently, plaque characterization at 3T requires a different set of coils compared with the global assessment of the entire course of the carotid arteries. Future generations of 16- to 32-channel carotid coils should be able to combine the best features of current 4- to 8-channel surface carotid coils and neurovascular coils. These will enable a comprehensive evaluation of the entire course of the carotid artery and detailed carotid bifurcation plaque characterization at 3T within a clinically acceptable 1-hour time frame. This comprehensive carotid artery evaluation with 3T MR imaging would be far superior to that which is possible with US or CT.

Artifacts↗
PubMed2005

The natural history of radiographically defined vertebrobasilar nonsaccular intracranial aneurysms.

BACKGROUND: Vertebrobasilar nonsaccular intracranial aneurysms (VBNIA) are characterized by dilatation, elongation, and tortuosity of the vertebrobasilar system. METHODS: The medical records and imaging of patients with vertebrobasilar fusiform aneurysms or dolichoectasia between 1989 and 2001 were reviewed. Prospective follow-up was obtained. RESULTS: One hundred and fifty-nine patients were identified (74% male) with 719 patient years of follow-up. Presenting events included: hemorrhage (3%), ischemia (28%), and compression (22%). The remainder were incidental. The 1-, 5-, and 10-year risk of cerebral infarction (CI) due toVBNIA is 2.7, 11.3, and 15.9% respectively. The risk of recurrent CI is 6.7% per patient year. Median survival was 7.8 years and death was most commonly due to ischemia. CONCLUSIONS: VBNIA are more common in men and typically present in the 6-7th decade. Recurrent CI is more common than hemorrhage risk.

Adult↗
PubMed2005

The Familial Intracranial Aneurysm (FIA) study protocol.

BACKGROUND: Subarachnoid hemorrhage (SAH) due to ruptured intracranial aneurysms (IAs) occurs in about 20,000 people per year in the U.S. annually and nearly half of the affected persons are dead within the first 30 days. Survivors of ruptured IAs are often left with substantial disability. Thus, primary prevention of aneurysm formation and rupture is of paramount importance. Prior studies indicate that genetic factors are important in the formation and rupture of IAs. The long-term goal of the Familial Intracranial Aneurysm (FIA) Study is to identify genes that underlie the development and rupture of intracranial aneurysms (IA). METHODS/DESIGN: The FIA Study includes 26 clinical centers which have extensive experience in the clinical management and imaging of intracerebral aneurysms. 475 families with affected sib pairs or with multiple affected relatives will be enrolled through retrospective and prospective screening of potential subjects with an IA. After giving informed consent, the proband or their spokesperson invites other family members to participate. Each participant is interviewed using a standardized questionnaire which covers medical history, social history and demographic information. In addition blood is drawn from each participant for DNA isolation and immortalization of lymphocytes. High- risk family members without a previously diagnosed IA undergo magnetic resonance angiography (MRA) to identify asymptomatic unruptured aneurysms. A 10 cM genome screen will be performed to identify FIA susceptibility loci. Due to the significant mortality of affected individuals, novel approaches are employed to reconstruct the genotype of critical deceased individuals. These include the intensive recruitment of the spouse and children of deceased, affected individuals. DISCUSSION: A successful, adequately-powered genetic linkage study of IA is challenging given the very high, early mortality of ruptured IA. Design features in the FIA Study that address this challenge include recruitment at a large number of highly active clinical centers, comprehensive screening and recruitment techniques, non-invasive vascular imaging of high-risk subjects, genome reconstruction of dead affected individuals using marker data from closely related family members, and inclusion of environmental covariates in the statistical analysis.

Clinical Protocols↗
PubMed2005

3.0-Tesla MR angiography of intracranial aneurysms: comparison of time-of-flight and contrast-enhanced techniques.

PURPOSE: To determine whether 3.0-T elliptical-centric contrast-enhanced (CE) magnetic resonance (MR) angiography is superior to 3.0-T elliptical-centric time-of-flight (TOF) MR angiography in the detection and characterization of intracranial aneurysms, and to determine whether increasing the acquisition matrix size in 3.0-T CE MR angiography improves image quality. MATERIALS AND METHODS: A total of 50 consecutive patients referred for MR angiographic evaluation of a known or suspected intracranial aneurysm underwent MR angiography, including three-dimensional TOF and elliptical-centric CE techniques at 3.0 T. The 3.0-T three-dimensional TOF and 3.0-T CE examinations were graded for image quality. A blind review identified the presence and location of aneurysms. RESULTS: A total of 28 aneurysms were identified in 23 of the 50 patients. The 3.0-T TOF MR angiography had a higher mean score for image quality than the 3.0-T elliptical-centric CE MR angiography (P < 0.0001). A total of 14 patients with aneurysms had conventional angiography for comparison. The 3.0-T TOF showed all the aneurysms, whereas 3.0-T CE MR angiography did not show 1 of 19 aneurysms when conventional angiography was the reference standard. CONCLUSION: For imaging intracranial aneurysms, 3.0-T TOF MR angiography offers better image quality than 3.0-T CE MR angiography using the elliptical-centric technique.

Adult↗
PubMed2005

Feasibility of in vivo, multicontrast-weighted MR imaging of carotid atherosclerosis for multicenter studies.

PURPOSE: To test the image quality (ImQ) and interscan coverage of MRI for measuring carotid atherosclerosis across multiple centers. MATERIALS AND METHODS: Thirty-nine subjects from five clinical sites (site 1: n=11; site 2: n=16; site 3: n=2; site 4: n=3; site 5: n=7) were imaged on GE 1.5T scanners using a standardized carotid imaging protocol with five weightings (T1, proton density (PD), T2, time-of-flight (TOF), and contrast-enhanced (CE) T1). MR technologists from the five sites received comprehensive protocol training. A maximum coverage of 24 mm (12 slices) was designed for each of four scans (baseline and at four, eight, and 13 weeks). The adequacy of coverage was calculated as the percentage of arteries with at least six slices matched across all four scans. ImQ was evaluated using an established five-point scale for each image. ImQ>or= 3 was considered acceptable for image analysis. RESULTS: Across five sites, the mean ImQ was 3.4-4.2 for T1W, 3.6-4.4 for CE-T1W, 3.4-4.2 for PDW, 3.3-4.2 for T2W, and 3.4-4.0 for TOF. The mean ImQ per site was 3.5-4.2. All sites generated at least six-slice coverage (mean=8.0-9.1) for all index carotid arteries. CONCLUSION: The ImQ and coverage values were comparable among clinical sites using a standardized carotid imaging protocol. With comprehensive protocol training, carotid MRI is technically feasible for use in multicenter studies.

Adult↗
PubMed2005

Sample size calculation for clinical trials using magnetic resonance imaging for the quantitative assessment of carotid atherosclerosis.

PURPOSE: To provide sample size calculation for the quantitative assessment of carotid atherosclerotic plaque using non-invasive magnetic resonance imaging in multi-center clinical trials. METHODS. As part of a broader double-blind randomized trial of an experimental pharmaceutical agent, 20 asymptomatic placebo-control subjects were recruited from 5 clinical sites for a multi-center study. Subjects had 4 scans in 13 weeks on GE 1.5 T scanners, using TOF, T1-/PD-/T2- and contrast-enhanced Tl-weighted images. Measurement variability was assessed by comparing quantitative data from the index carotid artery over the four time points. The wall/outer wall (W/OW) ratio was calculated as wall volume divided by outer wall volume. The percent lipid-rich/necrotic core (%LR/NC) and calcification (%Ca) were measured as a proportion of the vessel wall. For %LR/NC and %Ca, only those subjects that exhibited LR/NC or Ca components were used in the analysis. RESULTS: Measurement error was 5.8% for wall volume, 3.2% for W/OW ratio, 11.1% for %LR/NC volume and 18.6% for %Ca volume. Power analysis based on these values shows that a study with 14 participants in each group could detect a 5% change in W/OW ratio, 10% change in wall volume, and 20% change in %LR/NC volume (power = 80%, p < .05). The calculated measurement errors presume any true biological changes were negligible over the 3 months that subjects received placebo. CONCLUSION: In vivo MRI is capable of quantifying plaque volume and plaque composition, such as %lipid-rich/necrotic core and %calcification, in the clinical setting of a multi-center trial with low inter-scan variability. This study provides the basis for sample size calculation of future MRI trials.

Aged↗
PubMed2005

Enlarging vertebrobasilar nonsaccular intracranial aneurysms: frequency, predictors, and clinical outcome of growth.

OBJECT: Vertebrobasilar nonsaccular intracranial aneurysms (NIAs) are characterized by elongation, dilation, and tortuosity of the vertebrobasilar arteries. The goal of this study was to define the frequency, predictors, and clinical outcome of the enlargement of vertebrobasilar NIAs. METHODS: Patients with vertebrobasilar fusiform or dolichoectatic aneurysms demonstrated on imaging studies between 1989 and 2001 were identified. In particular, patients who had undergone serial imaging were included in this study and their medical records were retrospectively reviewed. Prospective information was collected from medical records or death certificates when available. Both initial and serial imaging studies were reviewed. The authors defined NIA enlargement as a change in lesion diameter greater than 2 mm or noted on the neuroradiologist's report. A Cox proportional hazards regression was used to model time from diagnosis of the vertebrobasilar NIA to the first documented enlargement as a function of various predictors. The Kaplan-Meier method was used to study patient death as a function of aneurysm growth. Of the 159 patients with a diagnosis of vertebrobasilar NIA, 52 had undergone serial imaging studies including 25 patients with aneurysm enlargement. Lesion growth significantly correlated with symptomatic compression at the initial diagnosis (p = 0.0028), lesion type (p < 0.001), and the initial maximal lesion diameter (median 15 mm in patients whose aneurysm enlarged compared with median 8 mm in patients whose aneurysm did not enlarge; p < 0.001). The mortality rate was 5.7 times higher in patients with aneurysm growth than in those with no enlargement after adjustment for patient age (p = 0.002). CONCLUSIONS: Forty-eight percent of vertebrobasilar NIAs demonstrated on serial imaging enlarged, and this growth was associated with significant morbidity and death. Significant risk factors for aneurysm enlargement included symptomatic compression at the initial diagnosis, transitional or fusiform vertebrobasilar NIAs, and initial lesion diameter. Further studies are necessary to determine appropriate treatments of this disease entity once enlargement has been predicted or occurs.

Adult↗
PubMed2005

Preangiographic evaluation of spinal dural arteriovenous fistulas with elliptic centric contrast-enhanced MR Angiography and effect on radiation dose and volume of iodinated contrast material.

BACKGROUND AND PURPOSE: The detection and localization of spinal dural arteriovenous fistulas (AVFs) remain diagnostic challenges. This study tested the hypothesis that elliptic centric contrast-enhanced MR angiography (MRA) can be used to detect spinal dural AVFs, predict the level of fistulas, and reduce the radiation dose and volume of iodinated contrast material associated with conventional angiography. METHODS: We examined 31 patients who presented with suspected spinal dural AVF between December 2000 and March 2004. All patients underwent MRA and conventional angiography. The effect of MRA on subsequent conventional angiography was assessed by analyzing total fluoroscopy time and volume of iodinated contrast material used. RESULTS: At angiography, spinal dural AVFs were diagnosed in 22 of 31 patients, and MRA depicted an AVF in 20 of the 22 patients. MRA findings correctly predicted a negative angiogram in seven of nine cases. Of the 20 true-positive MRA results, the level of the fistula was included in the imaging volume in 14. In 13 of these 14 cases, MRA results correctly predicted the side and the level of the fistula to within one vertebral level. Fluoroscopy time and the volume of contrast agent was reduced by more than 50% in the 13 patients with a spinal dural AVF in whom MRA prospectively indicated the correct level. CONCLUSION: Contrast-enhanced MRA can be used to detect spinal dural AVFs, predict the level of fistulas, and substantially reduce the radiation dose and volume of contrast agent associated with catheter spinal angiography.

Aged↗
PubMed2004

Improved venous suppression and spatial resolution with SENSE in elliptical centric 3D contrast-enhanced MR angiography.

The elliptical centric (EC) view order samples a 3DFT acquisition from the center of k-space outward, and when applied to contrast-enhanced MR angiography (CE-MRA) provides intrinsic venous suppression. This is because the veins enhance several seconds after the scan is initiated, and are thus encoded solely by noncentral k-space frequencies. A separate method, sensitivity encoding (SENSE), accelerates the k-space sampling rate by reducing the phase FOV or, equivalently, by increasing the k-space sampling interval, and has been used to increase spatiotemporal resolution. We hypothesized that by combining SENSE with EC, sampling of central k-space would be accelerated and the k-space radius at which the veins first showed contrast enhancement would be increased over a reference scan, thus providing improved venous suppression and spatial resolution without additional scan time. This hypothesis was studied with the use of phantom and carotid CE-MRA experiments, and the results demonstrated an approximate 25% reduction in venous signal when SENSE was used.

Blood Flow Velocity↗
PubMed2004

Internal jugular vein sampling in adrenocorticotropic hormone-dependent Cushing's syndrome: a comparison with inferior petrosal sinus sampling.

OBJECTIVE: Distinguishing between pituitary-dependent Cushing's syndrome (CS) and occult ectopic ACTH syndrome can be extremely difficult. Bilateral inferior petrosal sinus sampling has been shown to have the highest diagnostic accuracy in this subtype evaluation. Internal jugular vein sampling (IJVS) has been reported as a potentially safer invasive alternative, but data are limited. Our objective was to compare the sensitivity and specificity of bilateral IJVS and bilateral inferior petrosal sinus sampling (IPSS) in patients with ACTH-dependent CS. DESIGN: We prospectively collected blood samples from the inferior petrosal sinus and internal jugular vein of consecutive patients with ACTH-dependent CS. PATIENTS: The study group included 35 patients: 32 with pituitary-dependent CS (positive immunohistochemical findings for ACTH pituitary tumour or biochemical cure after pituitary surgery) and three with histologically proven ectopic ACTH syndrome. MEASUREMENTS: Inferior petrosal sinus sampling and bilateral IJVS were performed simultaneously before and after administration of corticotropin-releasing hormone (CRH), and ratios of central-to-peripheral ACTH concentrations were calculated. RESULTS: The basal IJVS central-to-peripheral ACTH ratios were diagnostic for pituitary-dependent CS (> 2) in 15 patients (46.9%), as were basal inferior petrosal sinus sampling central-to-peripheral ACTH ratios in 29 patients (90.6%). The post-CRH IJVS central-to-peripheral ACTH ratios were diagnostic for pituitary-dependent disease (> 3) in 24 patients (75%), as were post-CRH inferior petrosal sinus sampling central-to-peripheral ACTH ratios in 28 patients (87.5%). In the three patients with ectopic ACTH CS, the IJVS and inferior petrosal sinus sampling pre- and post-CRH ACTH ratios were correctly negative. The overall sensitivity of combined pre- or post-CRH was 81.3% for IJVS and 93.8% for inferior petrosal sinus sampling. Because of the difference between mean ratios in the two techniques, new criteria for IJVS were mathematically calculated: a pre-CRH central-to-peripheral ACTH ratio of 1.59 and a post-CRH central-to-peripheral ACTH ratio of 2.47 maximized sensitivity and specificity when both of these are equally taken into consideration. CONCLUSION: In conclusion, IJVS is not superior to inferior petrosal sinus sampling for establishing the cause of ACTH-dependent CS. When new criteria of basal (> 1.6) and post-CRH (> 2.5) central-to-peripheral ACTH gradients were applied to ACTH ratios from IJVS, the sensitivity of this test was maximized. However, confirmatory inferior petrosal sinus sampling is recommended when there is a lack of a central-to-peripheral ACTH gradient and when there is only a gradient above the cut-off on basal (pre-CRH) sampling.

ACTH Syndrome, Ectopic↗
PubMed2004

Follow-up of intracranial aneurysms in autosomal-dominant polycystic kidney disease.

BACKGROUND: Approximately 8% of autosomal-dominant polycystic kidney disease (ADPKD) patients have intracranial aneurysms. The risk of growth and rupture of those discovered by presymptomatic screening is key to the feasibility and success of a screening program. This study was initiated to ascertain this risk. METHODS: ADPKD patients were offered screening with magnetic resonance (MR) imaging that included three-dimensional time-of-flight MR angiographic and three-dimensional phase-contrast sequences. Patients with aneurysms were recommended periodic surveillance, initially at 6 months and yearly, and less frequently after demonstration of their stability. RESULTS: Twenty-two saccular and one fusiform aneurysms were detected at the initial screening in 21 patients from 19 families (seven men and 14 women, 47.9 +/- 10.6 years old). All the saccular aneurysms were small (mean diameter 3.5 mm, range 2.0 to 6.5 mm) and the majority (77%) in the anterior circulation. Two patients died from unrelated causes without further follow-up. One patient was lost to follow-up. A new 2 mm middle cerebral artery aneurysm developed in one patient. One aneurysm increased from a size of 4 mm to 5 mm after a follow-up of 105 months. No aneurysmal development or growth occurred in the remaining 16 patients. No aneurysmal rupture occurred during a mean imaging follow-up of 81 months and a mean clinical follow-up of 92 months. During the period of the study, two additional ADPKD patients, with three intracranial aneurysms detected elsewhere by presymptomatic MR angiographic screening, were referred for surgical treatment. The larger size of these aneurysms (10, 8, and 8 mm) probably reflects referral bias. CONCLUSION: Most intracranial aneurysms detected by presymptomatic screening in ADPKD patients are small and in the anterior circulation. The follow-up results do not suggest an increased risk for growth and rupture, compared to those of intracranial aneurysms in the general population. These data do not support widespread screening for intracranial aneurysms in the ADPKD population.

Adult↗
PubMed2004

Evaluation of classic 2D time-of-flight MR angiography in the depiction of severe carotid stenosis.

OBJECTIVE: The purpose of this study is to determine the sensitivity, specificity, and clinical utility of classic 2D time-of-flight MR angiography (acquired with derated gradients) as an aid to predicting severe carotid stenosis. SUBJECTS AND METHODS: Our study population was composed of 68 patients, yielding 133 carotid bifurcations for analysis. A 2D time-of-flight MR angiography pulse sequence was modified to provide greater sensitivity for carotid stenosis, which resulted in visualization of a carotid stenosis with a 70% or greater diameter as a signal void. Contrast-enhanced MR angiography was performed with the elliptical centric view order. Multiple overlapping thin-slab acquisition (MOTSA) MR angiography was performed in select patients. Digital subtraction angiography was performed in 51 patients, and the findings were used as the gold standard. In the remaining patients, findings on carotid duplex Doppler sonography and at surgery and clinical follow-up were used as the gold standard. RESULTS: In 51 patients for whom a digital subtraction angiogram was available, we found that the sensitivity of classic 2D time-of-flight MR angiography for prediction of carotid stenosis with a 70% or greater diameter was 94%, and the specificity of the technique was 97%. In three patients with severe carotid stenosis, the stenoses that appeared as signal voids on the classic 2D time-of-flight MR angiography were underestimated on contrast-enhanced MR angiography. Severe stenosis was confirmed by subsequent digital subtraction angiography, surgical results, or both. Discrepancies between findings on MOTSA MR angiography and contrast-enhanced MR angiography were resolved with classic 2D time-of-flight MR angiography. Classic 2D time-of-flight MR angiography increased diagnostic confidence of a severe stenosis in three patients with focal internal carotid artery stenosis. CONCLUSION: Classic 2D time-of-flight MR angiography has a high sensitivity and specificity for predicting carotid bifurcation stenosis of 70% or greater diameter. These probability measures allowed the detection of three significant stenoses that would have been missed on contrast-enhanced MR angiography and provided greater diagnostic confidence than contrast-enhanced or MOTSA MR angiography alone.

Aged↗
PubMed2004

Prospective risk of hemorrhage in patients with vertebrobasilar nonsaccular intracranial aneurysm.

OBJECT: Nonsaccular intracranial aneurysms (NIAs) are characterized by dilation, elongation, and tortuosity of intracranial arteries. Dilemmas in management exist due to the limited regarding the natural history of this disease entity. The objective of this study was to determine the prospective risk of subarachnoid hemorrhage (SAH) in patients with vertebrobasilar NIAs. METHODS: All patients with vertebrobasilar fusiform or dolichoectatic aneurysms that had been radiographically demonstrated between 1989 and 2001 were identified. These patients' medical records were retrospectively reviewed. A prospective follow-up survey was sent and death certificates were requested. Based on results of neuroimaging studies, the maximal diameter of the involved artery, presence of SAH, and measurements of arterial tortuosity were recorded. Nonsaccular intracranial aneurysms were classified according to their radiographic appearance: fusiform, dolichoectatic, and transitional. Dissecting aneurysms were excluded. The aneurysm rupture rate was calculated based on person-years of follow up. Predictive factors for rupture were evaluated using univariate analysis (p < 0.05). One hundred fifty-nine patients, 74% of whom were men, were identified. The mean age at diagnosis was 64 years (range 20-87 years). Five patients (3%) initially presented with hemorrhage; four of these patients died during follow up. The mean duration of follow up was 4.4 years (692 person-years). Nine patients (6%) experienced hemorrhage after presentation; six hemorrhages were definitely related to the NIA. The prospective annual rupture rate was 0.9% (six patients/692 person-years) overall and 2.3% in those with transitional or fusiform aneurysm subtypes. Evidence of aneurysm enlargement or transitional type of NIA was a significant predictor of lesion rupture. Six patients died within 1 week of experiencing lesion rupture. CONCLUSIONS: Risk of hemorrhage in patients harboring vertebrobasilar NIAs is more common in those with evidence of aneurysm enlargement or a transitional type of aneurysm and carries a significant risk of death.

Adult↗
PubMed2004

Evaluation and management of transient ischemic attack and minor cerebral infarction.

After immediate intervention for cerebral infarction or transient ischemic attack (TIA), the primary goal is secondary prevention of future cerebral ischemia and prevention of complications related to the initial ischemic event. The goals of the diagnostic evaluation are to (1) determine potential contributing mechanisms (cardioembolic, large-vessel disease of the extracranial and intracranial vessels, small-vessel disease, coagulation defects, and cryptogenic), (2) identify contributing risk factors (hypertension, hyperlipidemia, tobacco use, diabetes), and (3) complete the evaluation in a cost-effective and safe manner. We provide a sequential approach to the diagnostic evaluation of cerebral infarction or TIA to optimize diagnostic yield of testing, minimize cost and potential harm to the patient, and provide information that will change management. This systematic approach focuses on 6 important questions: (1) Are the symptoms consistent with a cerebral infarction or TIA (versus nonischemic pathology)? (2) Where does the ischemic event localize? (3) What etiologies and mechanisms of cerebral infarction and TIA are possible? (4) What is the prevalence of each potential etiology? (5) What treatments are available for this etiology? (6) What tests and studies are useful to evaluate this etiology?

Adult↗