A multicenter, site-independent, blinded study to compare the diagnostic accuracy of contrast-enhanced magnetic resonance angiography using 1.0M gadobutrol (Gadovist) to intraarterial digital subtraction angiography in body arteries.

PURPOSE: Prospective evaluation of diagnostic accuracy of single field-of-view contrast-enhanced MR Angiography (ceMRA) with 1.0M gadobutrol compared to intraarterial DSA in body arteries. MATERIALS AND METHODS: In an European multicenter study 179 patients underwent ceMRA and DSA. For each indication five prospectively defined vessel segments were evaluated by local investigators onsite and by three site-independent blinded readers (BR) independently. RESULTS: The agreement between ceMRA and DSA diagnosis was statistically significant in the onsite (96.6%) and blinded reader (86.6-90.2%) evaluation. Sensitivity, specificity, accuracy, positive (PPV) and negative predictive values (NPV) for detection of relevant stenosis (>50%) were calculated for the right and left internal carotid arteries, and common and external iliac arteries: Sensitivity was 95-98% (onsite) and 76-96% (BR), specificity 94-96% (onsite) and 86-94% (BR), accuracy 96% (onsite) and 87-93% (BR), NPV 98-99% (onsite) and 84-98% (BR), and PPV 79-93% (onsite) and 44-91% (BR), respectively. CONCLUSION: CeMRA of body arteries using 1.0M gadobutrol provides diagnostic information comparable to intraarterial DSA.

Time-resolved contrast-enhanced magnetic resonance angiography of the carotid arteries: diagnostic accuracy and inter-observer variability compared with selective catheter angiography.

RATIONALE AND OBJECTIVES: To assess the diagnostic accuracy and interobserver variability of contrast-enhanced magnetic resonance angiography (CE-MRA) in a time-resolved technique compared with digital subtraction angiography (x-ray DSA) in patients with suspected stenoses of the internal carotid artery. MATERIALS AND METHODS: A total of 43 patients were enrolled in this prospective study. All patients underwent selective x-ray DSA involving a total of 84 carotid arteries. CE-MRA was performed in a time-resolved technique with a fast gradient-echo sequence on a 1.5 T MR scanner: TR 3.8 milliseconds, TE 1.49 milliseconds. Four consecutive measurements, each a duration of 10 seconds, were performed with omission of measuring bolus transit time. Four independent radiologists scored the degree of stenosis. The interobserver variability was calculated for CE-MRA and x-ray DSA. RESULTS: In the 43 cases, at least one MRA measurement showed arterial contrast without venous degradation. Compared with x-ray DSA the mean sensitivity and specificity for grading stenosis > or = 70% were 98% and 86%, respectively. The interobserver agreement was substantial with no significant difference between CE-MRA (kappa value 0.794) and x-ray DSA (kappa value 0.786). CONCLUSIONS: The short acquisition time of a fast CE-MRA sequence allows a selective visualization of the internal carotid arteries without degradation from venous enhancement. It is a reliable method with a good interobserver agreement.

Hybrid management of aortic rupture and lung failure: pumpless extracorporeal lung assist and endovascular stent-graft.

Acute traumatic aortic rupture represents a potentially life-threatening situation. Because of the extremely high early mortality, emergency surgical repair used to be the preferred method of treatment. This group of patients usually is seen with a wide variety of injuries and comorbid conditions, all of which have a major impact on surgical outcome. We present an alternative hybrid approach that combines on-site placement of pumpless extracorporeal lung assist, subsequent patient transfer, and endovascular stent-graft implantation. This procedure may be a potentially useful strategy to reduce the comorbidity and the mortality of both lesions.

Preoperative evaluation of carotid artery stenosis: comparison of contrast-enhanced MR angiography and duplex sonography with digital subtraction angiography.

BACKGROUND AND PURPOSE: Contrast-enhanced MR angiography and extracranial color-coded duplex sonography are noninvasive, preoperative imaging modalities for evaluation of carotid artery stenosis. Innovative techniques and improvements in image quality require frequent reassessment of accuracy, reliability, and diagnostic value compared with those of digital subtraction angiography (DSA). We evaluated contrast-enhanced MR angiography and duplex sonography compared with DSA for detection of high-grade carotid artery stenoses. METHODS: Four readers, blinded to clinical symptoms and the outcome of other studies, independently evaluated stenoses on contrast-enhanced MR angiograms in 71 vessels of 39 symptomatic patients. Duplex sonography was also performed in all vessels. The severity of stenosis was defined according to North American Symptomatic Carotid Endarterectomy Trial criteria (0-29%, 30-69%, 70-99%, 100%). Results of both modalities were compared with the corresponding DSA findings. RESULTS: Contrast-enhanced MR angiography had a sensitivity and specificity of 94.9% and 79.1%, respectively, for the identification of carotid artery stenoses of 70% or greater. Sensitivity and specificity of duplex sonography were 92.9% and 81.9%, respectively. Combining data from both tests revealed a sensitivity and specificity of 100% and 81.4%, respectively, for concordant results (80% of vessels). CONCLUSION: Concordant results of contrast-enhanced MR angiography and duplex sonography increase the diagnostic sensitivity to 100%. The reliability of MR angiography is comparable to that of DSA. The combination of contrast-enhanced MR angiography and duplex sonography might be preferable over DSA for preoperative evaluation in most patients, thus reducing the risk of perioperative morbidity and improving the overall outcome.

Differentiation of cerebral tumors using multi-section echo planar MR perfusion imaging.

OBJECTIVE: We have investigated the performance of magnetic resonance (MR) perfusion imaging to differentiate between astrocytomas grade II, grade III and glioblastomas in a prospective study. MATERIALS AND METHODS: In 33 patients with suspected supratentorial primary cerebral tumors we performed multi-section Echo Planar MR perfusion imaging. Regional cerebral blood volume (rCBV) maps were calculated and the maximum rCBV was determined from the entire lesion. This value was divided by the mean rCBV value from the contralateral side, which provided the rCBV index used in this study. The rCBV index was correlated with the histological tumor classification after stereotactic biopsy (n=7) or open resection (n=26). RESULTS: The maximum rCBV index was 1.2+/-0.8 for grade II astrocytomas (n=3), 4.0+/-1.2 for grade III astrocytomas (n=13), and 10.3+/-3.3 for glioblastomas (n=17). The difference between grade III astrocytomas and glioblastomas was highly significant (P<0.001). DISCUSSION AND CONCLUSION: The rCBV index measured with multi-section Echo Planar MR perfusion is capable of differentiating grade III astrocytomas from glioblastomas. It serves as an additional parameter to establish a diagnosis in cases where it is not possible to clearly differentiate between these types of tumors on the basis of conventional MR imaging. MR perfusion imaging also provides information about spatial heterogeneities within a tumor which might improve diagnostic performance. This technology may also be of interest for follow-up examinations after histological diagnosis and further treatment.

In vivo evaluation of the carotid wallstent on three-dimensional contrast material-enhanced MR angiography: influence of artifacts on the visibility of stent lumina.

PURPOSE: Contrast material-enhanced magnetic resonance (MR) angiography is increasingly used in postinterventional imaging after implantation of endovascular stents. The main limitations are stent-related artifacts compromising the visibility of the stent lumen. The aim of this in vivo study is the evaluation of contrast-enhanced MR angiography imaging characteristics of the carotid Wallstent. MATERIALS AND METHODS: The carotid arteries of 29 patients were examined with contrast-enhanced MR angiography 3-6 days and/or 7-23 months after implantation of a carotid Wallstent into the internal carotid artery. Images were evaluated with regard to the diameter and signal intensity (SI) of the visible stent lumen. Digital subtraction angiography (DSA) was used as the standard of reference. RESULTS: Stent-related artifacts on contrast-enhanced MR angiography caused an artificial lumen narrowing and a reduction of the SI within the stent. Artifacts were pronounced on imaging 3-6 days after stent implantation, but 68% of stents imaged 7-23 months after stent implantation presented with a significantly decreased artificial signal reduction and an improved visibility of the stent lumen. CONCLUSIONS: The results of this study indicate that a reliable evaluation of the stent lumen is limited as a result of an artificial decrease of the SI inside the stent. However, in follow-up examinations 7-23 months after stent implantation, visibility of the stent lumen was improved and diagnostic reliability of contrast-enhanced MR angiography was markedly increased. A probable explanation for this phenomenon might be the formation of a neointimal layer covering the stent struts and thereby reducing stent-related artifacts.

Left ventricular remodeling after pulmonary autograft aortic valve replacement: evaluation with color-Doppler echocardiography and magnetic resonance imaging.

The superior hemodynamic performance of the pulmonary autograft in aortic position is expected to reflect complete regression of hypertrophy and improved ventricular function. We evaluated and compared early and midterm transthoracic color-Doppler echocardiography (TTE) and magnetic resonance imaging (MRI) assessment concerning left ventricular (LV) function, LV mass regression, and performance of the semilunar valves. A total of 42 consecutive patients, mean age 36 +/- 6 years (range 15 to 56 years), were studied. TTE and MRI were performed preoperatively, at discharge, and at 6 and 12 months postoperatively. Left ventricular diameters and function and LV wall thickness and mass were assessed. There was no early and one late postoperative death. Maximum and mean LV outflow gradients were significantly reduced (p = 0.0001 and p = 0.0001, respectively). There was a significant reduction in left ventricular mass to near normal for all patients (p = 0.001) seen after 6 months. This was paralleled by significant reductions in the interventricular septum and posterior wall thickness, but difference was slight during further follow-up. There was a strong correlation between the results obtained by TTE and MRI for LV mass and ejection fraction (r = 0.86 and 0. 87, respectively). The pulmonary autograft operation gives excellent results that are translated into greater, rapid, and near complete regression of LV hypertrophy. Magnetic resonance imaging is a sensitive and noninvasive methodology that provides reliable visualization and quantification of ventricular performance.

Peripheral arterial balloon angioplasty: effect of short versus long balloon inflation times on the morphologic results.

PURPOSE: To evaluate the effect of different balloon inflation times on angiographic results in peripheral angioplasty. MATERIALS AND METHODS: Seventy-four infrainguinal arteriosclerotic lesions were randomized prospectively to undergo balloon dilation for 30 seconds (group I) or 180 seconds (group II). Each group consisted of 37 patients. Postinterventional angiograms were evaluated by two blinded readers. Dissections were graded as follows: 1 = no dissection; 2 = minor flap; 3 = extensive dissection membrane, not flow limiting; or 4 = flow-limiting flap. The rate of major-grade dissections (grades 3 and 4), residual stenosis (>30%), and further interventions were compared with the two-tailed chi(2) test. RESULTS: In group I, major dissections were noted in 16 patients (43%) compared with five patients (14%) in group II (P =.009). Residual stenoses were found in 12 patients (32%) in group I compared with five patients (14%) in group II (P =.096). The rate of additional interventions was significantly higher in group I than in group II (20 of 37 vs nine of 37; P =.017). CONCLUSION: A prolonged inflation time of 180 seconds improves the immediate angioplasty result of infrainguinal lesions compared to a short dilation strategy. Significantly fewer major dissections and a modest reduction of residual stenoses are observed. The requirement of costly and time-consuming further interventions is significantly reduced.

Corrosion of tungsten coils after peripheral vascular embolization therapy: influence on outcome and tungsten load.

The purpose of this study was to evaluate coil corrosion and the long-term outcome after peripheral vascular embolization therapy performed with tungsten coils. We studied 14 patients who received tungsten coils on an average of 26 months prior to follow-up. The protocol included plain radiography and contrast-enhanced magnetic resonance angiography to investigate corrosion of tungsten coils and recanalization of the embolized vessels. Whole blood, hair, and urine tungsten levels were assayed when available. Corrosion of tungsten coils was detected in 9 of 14 patients by plain radiography. No evidence of recanalization of the embolized vessel and no adverse clinical effects of tungsten resorption were detected. Blood levels of tungsten were elevated in 6 of 14 patients and urine levels of tungsten were elevated in all 12 patients tested. Tungsten coil corrosion and elevated tungsten levels in blood, hair, and urine were found in most patients, although no adverse clinical effects of tungsten resorption were detected. Since the overall effect of high tungsten blood levels remains unclear, its use as an implant should be avoided.

Iliac artery stent placement: clinical experience and short-term follow-up regarding a self-expanding nitinol stent.

PURPOSE: To evaluate the effectiveness, safety, and short-term patency rates of a self-expandable nitinol stent (JostentSelfX; Abbott Laboratories, Chicago, IL) for treatment of iliac artery stenoses. MATERIALS AND METHODS: In a prospective study, 34 chronic iliac artery stenoses were primarily treated in 27 patients (mean age, 61.7 years +/- 9.4) by placement of a JostentSelfX. Handling and visibility of the stent was scored on a 4-point scale. Before stent placement, within 3 days after stent placement and at 6 months follow-up, the clinical history, clinical stage according to the Rutherford classification, and the ankle-brachial index (ABI) were assessed. Intra-arterial digital subtraction angiography including measurement of the mean pressure gradient was performed at the time of stent placement and at 6 months follow-up or in case of recurrence of symptoms. The Wilcoxon signed rank test and Kaplan-Meier method were applied for statistical analysis. RESULTS: The immediate technical success rate was 94%. The clinical success rate immediately after the procedure was 96% and 85% at 6 months follow-up. Stent placement significantly decreased the severity of stenoses as well as the mean pressure gradients and significantly increased the ABI. Handling of the stent was judged good. No misplacement occurred. Foreshortening during deployment was negligible and no stent migration was seen. However, visibility of the stent during fluoroscopy was ranked as moderate to bad. Follow-up at 6 months revealed the cumulative angiographic primary patency rate (<50% restenosis and <10 mm Hg mean pressure gradient) to be 0.96. CONCLUSION: The evaluated self-expandable nitinol stent is an effective tool in treating iliac artery stenoses. Apart from poor visibility, handling was good. The angiographic patency rate is comparable with data reported in other stent trials.

Safety and efficacy of the Perclose suture-mediated closure device following carotid artery stenting under clopidogrel platelet blockade.

The aim of this study was evaluation of a closure device (Perclose, Menlo Park, Calif.) for closure of the femoral artery access site in patients undergoing aggressive anticoagulation and platelet blockade after carotid stenting. Fifty-five patients who received clopidogrel in addition to aspirin and heparin as medication for carotid stenting were included for suture of the femoral access site after using 7- or 8-F guide catheters. The technical success, the time for suture, the clotting parameters, and complications were examined. Follow-up investigations, including ultrasound and clinical examinations, were performed. The groin was checked for possible hematoma, pseudoaneurysm, arteriovenous fistula, and local infection. Technical success was obtained in 51 of 54 patients (94%) after a mean procedure time of 6 min (range 5-10 min). The suture device was not used in one patient (2%) for anatomical reasons and failed to obtain hemostasis in 3 of 54 (6%) patients. In 4 of 54 patients (7%) bleeding was observed at the punctured site 4-6 h after intervention which was treated by a compression bandage. The mean dedicated activated clotting time was 137 s (range 29-287 s) before intervention and 349 s (150-958 s) just before deploying the Perclose device. During follow-up after 2 days (range 2-6 days) and 6 months no further complications of the puncture site were observed except for two large groin hematomas. No major complications occurred. Closure of the femoral access site after carotid stenting using a Perclose closure device is safe and effective even in patients receiving an aggressive anticoagulation and antiplatelet therapy.