Carotid bifurcation CT angiography: assessment of interactive volume rendering

3D Rotational Angiography in Follow-Up of Clipped Intracranial Aneurysms

Introduction. 3D Rotational Angiography (RA) is indispensable for evaluation of intracranial aneurysms, providing infinite viewing angles and defining the aneurysm morphology. Its role in follow-up of clipped aneurysms remains unclear. We aimed to compare the aneurysm residue/recurrence detection rate of 3D RA with 2D digital subtraction angiography (DSA). Methods. 47 patients harboring 54 clipped aneurysms underwent both 2D DSA and 3D RA. The residual/recurrent aneurysms were classified into five grades and the images of both modalities were compared. Results. The residual/recurrent aneurysm detection rate was 53.70% (29/54 aneurysms) with 2D DSA and 66.67% (36/54 aneurysms) with 3D RA (P = 0.05). In 12 aneurysms, 3D RA upgraded the residue/recurrence among which nine had been completely not detected on 2D DSA and were found to have grade one or two residual necks on the 3D RA, and, in three cases, a small neck on 2D DSA turned out to be aneurysm sac on 3D RA. In a total of 5 aneurysms, the classification was downgraded by 3D RA. Conclusion. 3D RA picks up more aneurysm residue/recurrence; hence, both 2D DSA and 3D RA should be performed in follow-up evaluation of clipped aneurysms.

Evaluation of computer-assisted quantification of carotid artery stenosis

The purpose of this study was to evaluate the influence of advanced software assistance on the assessment of carotid artery stenosis; particularly, the inter-observer variability of readers with different level of experience is to be investigated. Forty patients with suspected carotid artery stenosis received head and neck dual-energy CT angiography as part of their pre-interventional workup. Four blinded readers with different levels of experience performed standard imaging interpretation. At least 1 day later, they performed quantification using an advanced vessel analysis software including automatic dual-energy bone and hard plaque removal, automatic and semiautomatic vessel segmentation, as well as creation of curved planar reformation. Results were evaluated for the reproducibility of stenosis quantification of different readers by calculating the kappa and correlation values. Consensus reading of the two most experienced readers was used as the standard of reference. For standard imaging interpretation, experienced readers reached very good (k = 0.85) and good (k = 0.78) inter-observer variability. Inexperienced readers achieved moderate (k = 0.6) and fair (k = 0.24) results. Sensitivity values 80%, 91%, 83%, 77% and specificity values 100%, 84%, 82%, 53% were achieved for significant area stenosis >70%. For grading using advanced vessel analysis software, all readers achieved good inter-observer variability (k = 0.77, 0.72, 0.71, and 0.77). Specificity values of 97%, 95%, 95%, 93% and sensitivity values of 84%, 78%, 86%, 92% were achieved. In conclusion, when supported by advanced vessel analysis software, experienced readers are able to achieve good reproducibility. Even inexperienced readers are able to achieve good results in the assessment of carotid artery stenosis when using advanced vessel analysis software.

Correlation between US-PSV and 64-Row MDCTA with Advanced Vessel Analysis in the Quantification of 50-70% Carotid Artery Stenosis

Purpose. To correlate ultrasonographic peak systolic velocity (US-PSV) and 64-row multidetector computed tomography angiography (MDCTA) with advanced vessel analysis (AVA) software in the quantification of 50–70% carotid artery stenosis. Materials and methods. 199 consecutive patients (247 arteries) with internal carotid artery (ICA) or third proximal bifurcation stenosis. Each patient was studied by duplex US (DUS) and 64-row MDCTA with AVA software. Results. DUS showed PSV measurements less than 125 cm/s in 51 carotid stenosis and a value greater than this in 196 arteries. 64-row MDCTA AVA software showed a grade of stenosis less than 50% in 42 carotid arteries while a greater 70% was found in 4 carotid arteries; then, carotid arteries with stenosis percentage between 50% and 70% were 201. Linear regression analysis showed a good linear correlation (r = 0.88) between MDCTA-AVA software percentage stenosis and PSV: between 50% grade of stenosis and PSV value corresponding to 133,6 cm/sec and between 70% stenosis and PSV value corresponding to 268 cm/sec. The sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) of this analysis were 93%, 82%, 97%, 75%, respectively. Conclusion. Linear correlation between PSV data and grade of stenosis from 50% to 70% obtained with 64-row MDCTA AVA software. Main PSV value corresponding to 50% and 70% grade of stenosis at AVA analysis.

[CT diagnostics of carotid artery stenosis]

CT angiography can be used to evaluate carotid artery stenosis with high diagnostic safety. In contrast to the gold standard digital subtraction angiography (DSA) it is a non-invasive procedure which yields information regarding the degree of stenosis as well as information about plaque morphology. Due to multiple reconstruction planes in 3 levels in maximum intensity projections (MIP) and the possibility to perform volume rendering (VR) reconstruction more information about the extent of carotid disease can be acquired. Due to the bolus tracking technique optimum contrast medium enhancement of the carotid artery with simultaneous minimization of venous artifacts is possible.

Grading of carotid artery stenosis with multidetector-row CT angiography: visual estimation or caliper measurements?

To assess the optimal method for grading carotid artery stenosis with computed tomographic angiography (CTA), we compared visual estimation to caliper measurements, and determined inter-observer variability and agreement relative to digital subtraction angiography (DSA). We included 46 patients with symptomatic carotid stenosis for whom CTA and DSA of 55 carotids was available. Stenosis quantification by CTA using visual estimation (CTA_VE) (method 1) was compared with caliper measurements using subjectively optimized wide window settings (method 2) or predefined contrast-dependent narrow window settings (method 3). Measurements were independently performed by two radiologists and two residents. To determine accuracy and inter-observer variability, we calculated linear weighted kappa, performed a Bland-Altman analysis and calculated mean difference (bias) and standard deviation of differences (SDD). For inter-observer variability, kappa analysis was “very good” (0.85) for expert observers using CTA_VE compared with “good” (0.61) for experts using DSA. Compared with DSA, method 1 led to overestimation (bias 5.8–8.0%, SDD 10.6–14.4), method 3 led to underestimation (bias −6.3 to −3.0%, SDD 13.0–18.1). Measurement variability between DSA and visual estimation on CTA (SDD 11.5) is close to the inter-observer variability of repeated measurements on DSA that we found in this study (SDD 11.6). For CTA of carotids, stenosis grading based on visual estimation provides better agreement to grading by DSA compared with stenosis grading based on caliper measurements.

Multidetector row CT of the brain and carotid artery: a correlative analysis

AIM

To evaluate the association between types of carotid plaque, the presence of prior ischaemic events detectable with CT, and patient's symptoms.

MATERIALS AND METHODS

Between January 2004 and May 2006, 112 patients were evaluated using multidetector row computed tomography angiography (MDCTA) of the carotid arteries and computed tomography (CT) of the brain. Carotid arteries were categorized by evaluating the degree of stenosis according to North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria, the type of plaque, and the presence of plaque ulceration. The brain was assessed via CT for the presence, type, and position of lesions. Chi-square tests, Student's t test, and simple logistic regression analysis were performed and the Cohen kappa test was applied for interobserver variability measurement.

RESULTS

The Chi-square test indicated a statistically significant association between the presence of fatty plaques (p=0.005) and CT-detectable lesions in the brain (p=0.004). Moreover, the number of patients with CT-detectable brain lesions was greater in patients with >70% stenosis than in those with <70% stenosis (p=0.007). Logistic regression confirmed the association between fatty plaque and symptoms (p=0.001), between >70% stenosis and symptoms (p=0.041), and an inverse association between calcified plaque and symptoms (p=0.009).

CONCLUSION

MDCTA allows adequate evaluation of the type of plaque. The results of the present study indicate that there is an association between cerebral lesions, symptoms, and fatty plaque in the carotid artery. The degree of stenosis also correlated with cerebral lesions and symptoms. According to the obtained data, the type of carotid plaque should be included among primary parameters in the classification of patients' risk class.

Multidetector-row CT angiography in the study of atherosclerotic carotid arteries

Pathologies of the carotid arteries, and in particular atherosclerosis, are now an important medical problem. Stroke is the third leading cause of severe disability in the Western World leading to millions of deaths every year. Extracranial carotid atherosclerotic disease is the major risk factor for stroke. In years, with the advent of multidetector-row CT (MDCT) scanners and the use of specific angiographic protocols (MDCTA), CT imaging of the carotid arteries has become increasingly effective. In addition, the volume data obtained can be further rendered to generate high-quality two-dimensional and three-dimensional images. The purpose of this study was to review the atherosclerotic carotid arteries, their complications and how MDCTA depicts them, underlining the benefits and pitfalls of this diagnostic technique.

Volume rendering versus maximum intensity projection in CT angiography: what works best, when, and why

The introduction and widespread availability of 16-section multi-detector row computed tomographic (CT) technology and, more recently, 64-section scanners, has greatly advanced the role of CT angiography in clinical practice. CT angiography has become a key component of state-of-the-art imaging, with applications ranging from oncology (eg, staging of pancreatic or renal cancer) to classic vascular imaging (eg, evaluation of aortic aneurysms and renal artery stenoses) as well as newer techniques such as coronary artery imaging and peripheral runoff studies. With an average of 400-1000 images in each volume data set, three-dimensional postprocessing is crucial to volume visualization. Radiologists now have workstations that provide capabilities for evaluation of these data sets by using a range of software programs and processing tools. Although different systems have unique capabilities and functionality, all provide the options of volume rendering and maximum intensity projection for image display and analysis. These two postprocessing techniques have different advantages and disadvantages when used in clinical practice, and it is important that radiologists understand when and how each technique should be used.

Volume changes of experimental carotid sidewall aneurysms due to embolization with liquid embolic agents: a multidetector CT angiography study

Iodine-containing polyvinyl alcohol polymer (I-PVAL) is a novel precipitating liquid embolic that allows for artifact-free evaluation of CT angiography (CTA). As accurate aneurysm volumetry can be performed with multidetector CTA, we determined volumes of experimental aneurysms before, immediately after, and 4 weeks after embolization of 14 porcine experimental carotid sidewall aneurysms with this liquid embolic. An automated three-dimensional software measurement tool was used for volumetric analysis of volume-rendering CTA data. Furthermore, intra-aneurysmal pressure changes during liquid embolization were measured in four silicone aneurysms and potential polymer volume changes within 4 weeks were assessed in vitro. Liquid embolic injection was performed during temporary balloon occlusion of the aneurysm neck, resulting in a mean occlusion rate of 98.3%. Aneurysms enlarged significantly during embolization by 61.1 +/- 28.9%, whereas a significant shrinkage of 5.6 +/- 2.7% was observed within the follow-up period. Histologic analysis revealed an inflammatory foreign body reaction with partial polymer degradation. In silicone aneurysm models, intra-aneurysmal pressure remained unchanged during liquid embolic injection, whereas balloon inflation resulted in a mean pressure increase of 31.2 +/- 0.7%. No polymer shrinkage was observed in vitro. The aneurysm enlargement noted was presumably due to pressure elevation after balloon inflation, which resulted in dilatation of the weak venous wall of the newly constructed aneurysm--another shortcoming of this experimental aneurysm model. The volume decrease after 4 weeks expressed partial polymer degradation.

Volume Determination of Intracranial Aneurysms Using 16-Row Multislice Computed Tomography Angiography

OBJECTIVE

To assess multislice computed tomography (CT) angiography for volume determination of intracranial aneurysms.

METHODS

Submillimetric 16-row multislice CT angiography was performed with optimized scan parameters on precision spheres and a soft carotid artery model harboring 3 aneurysms connected to a pulsatile circuit. The CT angiography images were produced using optimized techniques for axial, multiplanar reformation, maximum intensity projection, surface-shaded display, and volume-rendered images. Measurements were made with electronic precision calipers by segmentation according to the method of Cavalieri and by the use of automated volumetric analysis software.

RESULTS

Segmentation resulted in precise and accurate volume estimates of aneurysms, but small volumes were underestimated and evaluation time was long (36:44 minutes). Automated volume evaluation from volume-rendered reconstructions also resulted in low measurement error, although the evaluation process was significantly faster (3:25 minutes; P < 0.0001).

CONCLUSIONS

The use of an automated volume analysis tool on volume-rendered reconstructions is recommended for time-efficient volume assessment of intracranial aneurysms.

[Diagnostic evaluation of carotid artery stenoses with multislice CT angiography. Review of the literature and results of a pilot study]

BACKGROUND

The accurate evaluation of carotid artery stenoses is important for therapeutic decision making. Catheter digital subtraction angiography (DSA) still represents the gold standard, while the advent of multislice CT (MSCT) has led to improved temporal and spatial resolutions of CTA.

MATERIAL AND METHODS

In a pilot study, we investigated 14 diseased vessels in 9 symptomatic patients (7m, 2f; mean age 60.7+/-10,9 years) comparing biplanar DSA with standardized 16-slice MS-CTA. The degree of stenosis was evaluated in a consensus reading following modified NASCET criteria.

RESULTS

DSA demonstrated 4 occlusions, 5 high-grade stenoses (>70%) and 5 lower-grade stenoses (<70%). One dissecting, infrapetrous stenosis was not adequately quantified by CTA due to a close topographic relation to the skull base. In the carotid bifurcation (n=13), an excellent correlation was demonstrated between DSA and CTA with a correlation coefficient of 0.99.

CONCLUSION

MS-CTA has a good diagnostic potential in the evaluation of carotid artery stenoses. Larger studies will need to demonstrate the relative diagnostic value for different subtypes of stenosis and for different reader experience levels.

CTA der A.�carotis mit unterschiedlichen CT-Ger�ten

Noninvasive modalities like CTA are increasingly replacing selective angiography in the evaluation of carotid artery stenosis. Dedicated scan protocols and contrast injection techniques are mandatory for the morphological assessment of carotid artery stenosis. These protocols need to be adapted to different scanner types. The delineation of plaque components and the residual lumen is improved with high resolution scan protocols and dedicated reconstruction algorithms. The exact delineation of in-stent stenosis remains limited. Standardization of postprocessing is crucial in order to attain reproducible results. Multislice spiral CT allows reliable grading of carotid artery stenosis. Relevant venous opacification and pulsation artifacts have to be expected with 4-slice scanners, the short scan time of the latest CT scanners minimize these problems.

Systematic Review of Computed Tomographic Angiography for Assessment of Carotid Artery Disease

Background and Purpose— To review the literature on the diagnostic accuracy of computed tomographic angiography (CTA) compared with arteriography/intra-arterial digital subtraction angiography as reference standard for assessment of symptomatic carotid artery disease.

Methods— The PubMed, MEDLINE, PREMEDLINE, EMBASE, and CINAHL databases were searched to retrieve studies published between 1990 and July 2003, comparing CTA and intra-arterial digital subtraction angiography in patients with symptomatic carotid artery disease that presented raw data for detection of a <70% or 70% to 99% stenosis or an occlusion. Two observers independently assessed methodological quality and constructed 2×2 tables for sensitivity and specificity of CTA for detection of a 70% to 99% stenosis versus <70% stenosis or an occlusion, and for <99% stenosis versus occlusion. A bivariate random effects model was used to calculate the pooled sensitivity and specificity of CTA for detection of these lesions.

Results— Some 864 patients (66% male) with a mean age of 66 years were studied in the 28 studies included in the meta-analysis. In all studies, a single-slice CT-scan was used. Only 8 studies satisfied all methodological quality criteria. The pooled sensitivity and specificity for detection of a 70% to 99% stenosis were 85% (95% CI, 79% to 89%) and 93% (95% CI, 89% to 96%), respectively. For detection of an occlusion, the sensitivity and specificity were 97% (95% CI, 93% to 99%) and 99% (95% CI, 98% to 100%), respectively. Incomplete reporting of demographic characteristics and technical differences in the individual studies obstructed a meaningful subgroup analysis.

Conclusions— CTA is an accurate modality for detection of severe carotid artery disease, especially for detection of occlusions. The fair methodological quality of the included studies must be taken into account when interpreting these results.

The diagnostic accuracy of computed tomography angiography for traumatic or atherosclerotic lesions of the carotid and vertebral arteries: a systematic review

INTRODUCTION

Helical computed tomography angiography (CTA) has become an established technique for evaluating atherosclerosis of the cerebrovascular arteries. However, the role of CTA in penetrating and blunt trauma to the carotid and vertebral arteries is not well defined. We conducted a systematic literature review to determine the diagnostic accuracy of CTA for atherosclerotic, penetrating and blunt lesions in the carotid and vertebral arteries.

METHODS

We searched MEDLINE and EMBASE databases to identify studies evaluating the diagnostic accuracy of CTA of the carotid and vertebral arteries published between January 1, 1992 and December 31, 2002. Two reviewers independently assessed abstracts and full text to determine study eligibility. Information on methodological quality, imaging technique and diagnostic accuracy was abstracted from all eligible studies by three independent reviewers. We pooled sensitivity and specificity data from diagnostic accuracy studies of high methodological quality.

RESULTS

Forty-three articles met the inclusion criteria and were included in the review. Thirty studies examined atherosclerotic disease, two blunt trauma, two penetrating trauma and nine examined patients with other pathology. Pooled data from 15 higher quality studies demonstrated that CTA had a sensitivity of 95% (91-97% CI) for detecting severe (>70%) atherosclerotic stenosis of the carotid artery. The specificity of CTA for severe stenosis was also high 98% (96-99% CI). CTA remained a sensitive technique (95%; 93-97% CI) when the criterion for a positive result is relaxed to moderate or greater (>30%) stenosis. Two studies raised concerns about the use of CTA in the blunt trauma setting, suggesting that CTA may not be sensitive for detecting small intimal injuries, although both of these studies used older technologies for either obtaining or viewing images. Conversely, two penetrating trauma studies concluded that the sensitivity of CTA was high.

CONCLUSIONS

Our findings demonstrate that CTA is both a sensitive and specific imaging technique for identifying severe atherosclerotic stenosis and occlusion of the carotid arteries. However, there is currently not enough high quality evidence to accurately estimate the sensitivity and specificity of CTA in the setting of blunt or penetrating trauma.

Comprehensive imaging of ischemic stroke with multisection CT

Computed tomography (CT) is an established tool for the diagnosis of ischemic or hemorrhagic stroke. Nonenhanced CT can help exclude hemorrhage and detect "early signs" of infarction but cannot reliably demonstrate irreversibly damaged brain tissue in the hyperacute stage of ischemic stroke. Further evaluation of patients with ischemic stroke should include differentiation between reversible and irreversible brain damage, which is essential for choosing an appropriate therapy. Perfusion CT provides information about brain perfusion, which permits differentiation of irreversibly damaged brain tissue from reversibly impaired "tissue at risk." CT angiography can help detect stenosis or occlusion of extra- and intracranial arteries. Multisection CT allows the combined use of all three imaging modalities-nonenhanced CT, perfusion CT, and CT angiography-to rapidly obtain comprehensive information regarding the extent of ischemic damage in acute stroke patients. Specific patterns of findings are typically seen in ischemic stroke and can be analyzed more accurately with the combined use of multisection CT and MR imaging. Nevertheless, prospective studies involving a large number of patients will be needed to ascertain the treatment of choice for patients with each of these patterns of findings.

Three-dimensional helical computerized tomography angiography in the diagnosis, characterization, and management of middle cerebral artery aneurysms: comparison with conventional angiography and intraoperative findings

OBJECT

Middle cerebral artery (MCA) aneurysms can be difficult to detect and characterize. The authors describe the utility and impact of helical computerized tomography (CT) angiography for the evaluation of aneurysms in this location, and compare this modality with digital subtraction (DS) angiography and intraoperative findings.

METHODS

Two hundred fifty-one patients with suspected cerebral aneurysms underwent CT angiography. Two-dimensional multiplanar reformatted images and three-dimensional CT angiograms were examined by two independent readers in a blinded fashion. Results were compared with findings on DS angiograms to determine the relative efficacy of these modalities in the detection and characterization of aneurysms. Questionnaires completed by neurosurgeons and endovascular therapists were used to determine the impact of CT angiograms on aneurysm management. Twenty-eight patients harboring 31 MCA aneurysms and 26 patients without aneurysms were identified using CT angiography. The sensitivity of CT angiography and DS angiography for MCA aneurysms was 97%; both techniques showed 100% specificity. In 76% of evaluations, the CT angiography studies provided information not available on DS angiography examinations. For the characterization of aneurysms, CT angiography was rated superior (72%) or equal (20%) to DS angiography in 92% of cases evaluated (p < 0.001). Computerized tomography angiography was evaluated as the only study needed for patient triage in 82% of cases (p < 0.001), and as the only study needed for treatment planning in 89% of surgically treated (p < 0.001) and in 63% of endovascularly treated cases (p < 0.001). The information acquired on CT angiograms changed the initial treatment plan in 24 (67%) of these 36 complex lesions (p < 0.01). The aneurysm appearance intraoperatively was identical or nearly identical to that seen on CT angiograms in 17 (89%) of 19 of the surgically treated cases.

CONCLUSIONS

Computerized tomography angiography has unique advantages over DS angiography and is a viable alternative to the latter modality in the diagnosis, triage, and treatment planning in patients with MCA aneurysms.

Parameters affecting bolus geometry in CTA: a review

CT angiography (CTA) is based on acquisition of data during the arterial phase of contrast material passage. CTA needs timing of the contrast bolus, which should be based on accurate knowledge of bolus geometry. Experimental and human studies on bolus geometry and bolus timing in CTA were reviewed. Important parameters of bolus geometry and methods of bolus timing (test bolus and bolus tracking) are described. Recommendations are given for an optimal CTA protocol.

Critical review of non- or minimally invasive methods (duplex ultrasonography, MR- and CT-angiography) for evaluating stenosis of the proximal internal carotid artery

OBJECTIVE

to assess the performance of non- or minimally invasive methods (duplex ultrasonography, MR- and CT-angiography) in measuring stenosis of the proximal internal carotid prior to endarterectomy without preoperative intra-arterial digital subtraction angiography (DSA).

METHODS

systematic review of the literature (five databases, 1990 to February 2001). The value of each imaging technique was studied through its reproducibility and its sensitivity/specificity compared to DSA.

RESULTS

sensitivity exceeded 80% and specificity 90% in over two-thirds of the methodologically sound studies, regardless of technique, although direct comparisons between results had to be avoided since the findings originated from different populations. The main drawback of duplex ultrasonography is its levels of reproducibility. In contrast, only a few studies have addressed the reproducibility of MR- and CT-angiography. When the results of duplex and MR-angiography agree, the combination use of these two techniques provides a better diagnosis than either technique taken alone.

CONCLUSIONS

all three techniques appear suitable for measuring stenosis of the proximal internal carotid when compared to DSA.

CT angiography and MR angiography in the evaluation of extracranial carotid vascular disease

CTA and MRA techniques likely will continue to increase in use in the evaluation of the extracranial cerebrovascular system. The increasing reliance on noninvasive tests mirrors an overall concern with the risks and costs of more invasive examinations. Given the rapid development of the computer technology, data acquisition, and reconstruction algorithms in the past few years, it is apparent that CTA and MRA also will continue to improve.

Value of the CT angiography in the diagnosis of common carotid artery bifurcation disease: CT angiography versus digital subtraction angiography and color flow Doppler

OBJECTIVE

assessment of the degree of stenosis is the central point in the treatment of carotid stenosis. The purpose of our study was to assess whether invasive CT angiography (CTA) is a feasible alternative to the current invasive gold standard carotid digital subtraction angiography (DSA) and the current non-invasive gold standard color flow doppler.

SUBJECTS AND METHODS

about 178 patients with cerebrovascular disease underwent digital subtraction angiography (DSA), CFD and CTA. CTA was performed on a Somatom plus 4 (Siemens, Erlangen Germany). CT was performed with 2/3/2 (collimation/table feed/reconstruction interval) or 2/3/1 mm, start delay 15-20 s, flow 2.5-3.0 ml/s, using 120 ml non-ionic contrast medium (300 mg J/ml). Quantification of degree of stenosis was based on the perfused area in the axial slices. Plaque morphology (soft and hard) and ulceration were evaluated.

RESULTS

CTA detected nine cases of significant stenosis, which had been underestimated by DSA. CTA failed in two cases of a membraneous stenosis, which were underestimated, and in two cases with teeth artifacts. Calcifications were more readily appreciated by CTA than in CFD. In this respect, both methods were superior to DSA. CFD, DSA and CTA had a sensitivity of 100% for occlusions, respectively.

CONCLUSION

CT angiography is useful in case of inconclusive CFD in the pre- and postoperative phase, and as a third modality in case of disagreement between DSA and CFD.

Magnetic resonance angiography and evaluation of cervical arteries

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

Carotid MR angiography: phase II study of safety and efficacy for MS-325

PURPOSE

To evaluate the safety and efficacy of MS-325 in patients suspected of having carotid arterial disease.

MATERIALS AND METHODS

Fifty carotid arteries in 26 patients were imaged with three-dimensional spoiled gradient-recalled-echo magnetic resonance (MR) angiography at 5 and 50 minutes after injection of MS-325. MS-325 was administered intravenously as a single dose of 0.01, 0.03, or 0.05 mmol per kilogram of body weight as determined with a dose randomization scheme for four, nine, and 13 patients, respectively. Safety, including clinical laboratory changes and electrocardiographic monitoring, was assessed until approximately 3 days after injection. Conventional contrast agent-enhanced angiography was used as the standard of reference. Independent readers blinded to the dose interpreted the MR angiographic and conventional images. Images were assessed for location and extent of carotid arterial stenosis.

RESULTS

There were no severe or serious adverse events. For the determination of clinically significant stenosis (>70%) on the 5-minute images, sensitivity, specificity, and accuracy (P =.07, three-way comparison) were 100%, 100%, and 100%; 63%, 100%, and 88%; and 40%, 75%, and 55% at 0.01, 0.03, and 0.05 mmol/kg, respectively. Sensitivity and specificity for images at 50 minutes after MS-325 administration showed the same trends as the 5-minute images.

CONCLUSION

Overall accuracy for MS-325-enhanced carotid MR angiography performed during steady-state conditions of circulating contrast agent approximately 5 minutes after injection was high (88%-100%) at 0.03 and 0.01 mmol/kg. MS-325 was well tolerated at all evaluated doses.

Three-dimensional Contrastless Varicography by Spiral Computed Tomography

OBJECTIVE

to report and discuss preliminary results obtained in varicose limbs by means of a volume rendering (VR)-computed tomography (CT) technique without contrast medium injection.

MATERIALS AND METHODS

VR-CT and duplex sonography (US) were performed to visualise the superficial veins of the lower extremity in eight healthy and 12 varicose limbs.

RESULTS

VR-CT clearly demonstrated the 3D arrangement of the superficial veins and visualised small sized veins which were not visible at US examination.

CONCLUSIONS

VR-CT is not suitable for routine evaluation of varicose limbs. VR-CT 3D reconstructions may be useful in the evaluation of atypical varicosis. Further studies are needed to define the role of VR-CT in deep venous disease.