Multidetector CTA in the Quantification of Internal Carotid Artery Stenosis: Value of Different Reformation Techniques and Axial Source Images Compared With Selective Carotid Arteriography

Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach

BACKGROUND

The bridging vein (BV) and the tentorial sinus (TenS) are important venous structures in neurological surgery. These venous structures during the anterior transpetrosal approach (ATPA) have not been reported. The objective of this study is to examine the BV and the TenS in the subtemporal corridor during the ATPA and propose a technique to identify the BV preoperatively.

METHODS

This study included 126 patients treated via the ATPA. The BV and the TenS located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius).

RESULTS

Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003).

CONCLUSIONS

We showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, we found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively.

Volumetric assessment of the carotid bifurcation: an alternative concept to stenosis grading

BACKGROUND

To design a volumetric method for the assessment of carotid atheromatosis (CA) based on computed tomography (CT) angiography and three-dimensional (3D) reconstructions; to analyze the accuracy and optimal threshold values to differentiate between equivalent degrees of severity by duplex scanning and CT angiography (two-dimensional maximum intensity projection [2D MIP]; internal carotid artery stenosis [ICS] <50%; ICS >50%); and to assess the method's suitability to detect progression of CA.

METHODS

DESIGN

suitability and accuracy of a new diagnostic method.

POPULATION

90 carotid bifurcations (45 patients) were assessed with duplex scanning and CT angiography, and reevaluated after 12 ± 2 months follow-up. Determinations: Assessment of internal carotid artery (ICA) stenosis degree with duplex scanning and 2D MIP CT angiography projections. Volumetric assessment of carotid bifurcation by CT angiography (contrast volume [mm(3)] and density [Hounsfield units, H.U.] between 2-cm below and 1-cm above the anatomic bifurcation of the carotid artery [BifV], and its ratio with 1-cm segment of the common carotid artery [CCV]).

STATISTICAL ANALYSIS

descriptive statistics; intraobserver and interobserver agreement (Bland-Altman plot and intraclass correlation coefficient [ICC], accuracy of 3D volumetry and duplex scanning as referred to MIP 2D CT angiography as gold standard: sensitivity (Sens), specificity (Sp), kappa index, and receiver operating characteristic curves (ROCs).

RESULTS

Estimation of MIP 2D images (CT angiography) confirmed the findings of duplex scanning in 23 of 30 ICS <50% and 48 of 53 ICS >50% (Sens, 0.91; Sp, 0.77% kappa = 0.68). Three-dimensional volumetric assessment of carotid bifurcation showed an intraobserver and interobserver agreement with an ICC of 0.96 (95% confidence interval [CI], 0.904-0.985) and 0.94 (95% CI, 0.822-0.977), respectively. The BifV-to-CCV ratio was 5.2 ± 1.8 in the ICS <50% group versus 3.8 ± 1.3 in the ICS >50% group (P = 0.001). The optimal cutoff point of the BifV-to-CCV relationship was identified from the ROC curve in 4.1 (Sens, 0.75; Sp, 0.75; kappa, 0.46). At 12 months, a decrease of the average BifV with regard to the baseline value (475.45 [155.6] mm(3) × H.U. vs. 501.3 [171.9] mm(3) × H.U.; P = 0.04) was observed. CA progression was detected in 32 bifurcations (14 ICS <50%; 18 ICS> 50%), with a reduced bifurcation volume of 137.8 (71.4) mm(3) × H.U.; P < 0.001.

CONCLUSIONS

Volumetric assessment of carotid bifurcation is a new concept based on assessing plaque burden rather than its hemodynamic effect or maximum stenosis; thus, justifying its moderate accuracy with regard to ICS conventional ICA grading based on biplanar images. This method can be especially useful in plaque progression studies given its accuracy to detect minor changes in the arterial lumen.

Cerebral CT angiography and CT perfusion in acute stroke detection: a systematic review of diagnostic value

The purpose of this study was to analyse the diagnostic value of cerebral CT angiography (CTA) and CT perfusion (CTP) examinations in the detection of acute stroke based on a systematic review of the current literature. The review was conducted based on searching of seven databases for articles published between 1993 and 2013. Diagnostic value in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy was analysed from 21 articles which were found to meet selection criteria. The mean sensitivity, specificity, PPV, NPV and accuracy for CTA were significantly higher than those for CTP with 83.2% (95% CI: 57.9-100.0%), 95.0% (95% CI: 74.4-100%), 84.1% (95% CI: 50.0-100%), 97.1 (95% CI: 94.0-100%) and 94.0% (95% CI: 83.0-99.0) versus 69.9% (95% CI: 20.0-97.0%), 87.4 (95% CI: 61.0-100.0%), 76.4% (95% CI: 48.0-95.4%), 78.2% (95% CI: 55.8-93.9%) and 89.8% (95% CI: 75.7-97.1%), respectively. This analysis shows that CTA has high diagnostic value in detecting high degree of cerebral arterial stenosis (>70%) whereas CTP provides high specificity in the detection of ischemia and infarct tissue of brain.

Feasibility of low-dose contrast medium high pitch CT angiography for the combined evaluation of coronary, head and neck arteries

Purpose

To evaluate the image quality and radiation dose of combined heart, head, and neck CT angiography (CTA) using prospectively electrocardiography (ECG)-triggered high-pitch spiral scan protocol, compared with single coronary CTA.

Materials and Methods

151 consecutive patients were prospectively included and randomly divided into three groups. Group 1 (n = 47) underwent combined heart, neck, and head CTA using prospectively ECG-triggered high-pitch spiral (Flash) scan protocol with a single-phase intravenous injection of iodinated contrast and saline flush; Group 2 (n = 51) underwent single coronary CTA with Flash scan protocol; and Group 3 (n = 53) underwent single coronary CTA with prospective sequence scan protocol. All patients were examined on a dual source CT (Definition FLASH). The image quality was determined for each CT study.

Results

Patients of scanning protocol Group 1, 2, and 3 showed no significant differences in age, sex, heart rates, and BMI. Evaluation of coronary artery image quality showed comparable results in the three scanning protocol groups on a per patient-based analysis. In group 1, image quality was found to be sufficient to be diagnostic in all arterial segments of carotid arteries. The mean dose-length product (DLP) for group 1 was 256.3±24.5 mGy×cm and was significantly higher in comparison with group 2 (93.4±19.9 mGy×cm; p < 0.001). However, there was no significant difference of DLP between group 1 and group 3 (254.1±69.9 mGy×cm).

Conclusions

The combined heart, neck, and head arteries scan using prospectively electrocardiography (ECG)-triggered high-pitch spiral scan protocol in 1 single examination resulted in an excellent opacification of the aorta, the carotid arteries, and the coronary arteries and provided a good image quality with low radiation dose.

Chronic cerebrospinal venous insufficiency and venous stenoses in multiple sclerosis

OBJECTIVES

The traditional view that multiple sclerosis (MS) is an autoimmune disease has recently been challenged by the claim that MS is caused by chronic cerebrospinal venous insufficiency (CCSVI). Although several studies have questioned this vascular theory, the CCSVI controversy is still ongoing. Our aim was to assess the prevalence of CCSVI in Danish MS patients using sonography and compare these findings with MRI measures of venous flow and morphology.

METHODS

We investigated cervical and cerebral veins in 24 patients with relapsing-remitting MS (RRMS) and 15 healthy controls, using extracranial high-resolution ultrasound colour Doppler (US-CD) and transcranial colour Doppler sonography (TCDS), as well as magnetic resonance imaging (MRI) and phase-contrast MR blood flow measurements (PC-MR) of the cervical veins.

RESULTS

US-CD could not identify the left internal jugular vein (IJV) in one MS patient, other ultrasound examinations were normal in patients with MS. There was no difference in mean cross-sectional area of the IJV in MS patients compared with controls. Only one patient with MS and two healthy controls fulfilled one CCSVI criterion, and none fulfilled more than one CCSVI criterion. MR venography showed insignificant IJV stenosis (1-49%) in two patients with MS, whereas 50-69% IJV stenosis was detected in two healthy controls. There was no difference in PC-MR measurements of mean IJV blood flow between patients with MS and controls.

CONCLUSION

Our results do not corroborate the presence of vascular pathology in RRMS and we found no evidence supporting the CCSVI hypothesis.

Carotid artery stenosis: performance of advanced vessel analysis software in evaluating CTA

OBJECTIVES

The aim of this study was to evaluate time efficiency and diagnostic reproducibility of an advanced vessel analysis software for diagnosis of carotid artery stenosis.

MATERIAL AND METHODS

40 patients with suspected carotid artery stenosis received head and neck DE-CTA as part of their pre-interventional workup. Acquired data were evaluated by 2 independent radiologists. Stenosis grading was performed by MPR eyeballing with freely adjustable MPRs and with a preliminary prototype of the meanwhile available client-server and advanced visualization software syngo.via CT Vascular (Siemens Healthcare, Erlangen, Germany). Stenoses were graded according to the following 5 categories: I: 0%, II: 1-50%, III: 51-69%, IV: 70-99% and V: total occlusion. Furthermore, time to diagnosis for each carotid artery was recorded.

RESULTS

Both readers achieved very good specificity values and good respectively very good sensitivity values without significant differences between both reading methods. Furthermore, there was a very good correlation between both readers for both reading methods without significant differences (kappa value: standard image interpretation k=0.809; advanced vessel analysis software k=0.863). Using advanced vessel analysis software resulted in a significant time saving (p<0.0001) for both readers. Time to diagnosis could be decreased by approximately 55%.

CONCLUSIONS

Advanced vessel analysis application CT Vascular of the new imaging software syngo.via (Siemens Healthcare, Forchheim, Germany) provides a high rate of reproducibility in assessment of carotid artery stenosis. Furthermore a significant time saving in comparison to standard image interpretation is achievable.

Bending the curve: preoperative determination of bypass graft length and trajectory with curved planar reformatted computed tomography angiography: technical note

BACKGROUND AND IMPORTANCE

Cerebral revascularization continues to be an important technique for the treatment of cerebrovascular and vaso-occlusive diseases, and determination of appropriate graft sources and recipients is paramount to the success of the procedure. A tension-free anastomosis requires that harvested grafts be of an appropriate length to avoid complications. Volume-rendered contrast-enhanced computed tomography data sets may be useful in determining the desired length and path of the bypass graft and in the evaluation of appropriate recipient vessels. Curved planar reformation techniques may allow these properties to be determined in a novel, inexpensive, and efficient manner.

CLINICAL PRESENTATION

A 63-year-old patient with a left hemispheric perfusion deficit and without an external carotid artery was in need of high-flow cerebral revascularization. A radial artery graft spanning from the vertebral artery to the middle cerebral artery was proposed. Preoperative determination of graft length necessary and most efficient subcutaneous placement was desired. A standard computed tomography angiogram of the head and neck was obtained and imported into a computer workstation with curved planar reformatting capabilities.

CONCLUSION

Curved planar reformation technique can be used for preoperative planning of cerebral bypass procedures and is a novel, inexpensive, and efficient means of determining the desired length and path of the bypass graft and in the evaluation of appropriate recipient vessels.

Comparison between postprocessing techniques in the analysis of hepatic arteries using multi-detector-row computed tomography angiography

PURPOSE

Our purpose was to compare 4 different postprocessing techniques (maximum-intensity projection [MIP], multiplanar reconstruction, curved planar reconstruction, and volume rendering [VR]) for the study of hepatic arteries.

METHODS

One hundred thirty-seven patients who underwent multi-detector-row computed tomography angiography between August 2009 and January 2010 were retrospectively analyzed. For each patient and for each reconstruction method, the image quality was evaluated and the interobserver and intraobserver agreement was calculated according to Cohen statistics.

RESULTS

The Pearson r between the observers for the common hepatic artery measurement (Hounsfield unit) was good (r = 0.88). The VR showed a Cohen κ value of 0.78, and the highest image-quality score was obtained using MIP (total value, 384; mean value, 3.01) for observer 1 and using VR and MIP for observer 2 (mean value of 2.94).

CONCLUSIONS

Maximum-intensity projection and VR showed the optimal interobserver and intraobserver agreement and the highest quality scores and therefore should be used as postprocessing techniques when analyzing the hepatic arteries.