Carolin Brockmann

Dual-Energy CT Angiography in Peripheral Arterial Occlusive Disease

We sought to study the accuracy of dual-energy computed tomographic angiography (DE-CTA) for the assessment of symptomatic peripheral arterial occlusive disease of the lower extremity by using the dual-energy bone removal technique compared with a commercially available conventional bone removal tool. Twenty patients underwent selective digital subtraction angiography and DE-CTA of the pelvis and lower extremities. CTA data were postprocessed with two different applications: conventional bone removal and dual-energy bone removal. All data were reconstructed and evaluated as 3D maximum-intensity projections. Time requirements for reconstruction were documented. Sensitivity, specificity, accuracy, and concordance of DE-CTA regarding degree of stenosis and vessel wall calcification were calculated. A total of 359 vascular segments were analyzed. Compared with digital subtraction angiography, sensitivity, specificity, and accuracy, respectively, of CTA was 97.2%, 94.1%, and 94.7% by the dual-energy bone removal technique. The conventional bone removal tool delivered a sensitivity of 77.1%, a specificity of 70.7%, and an accuracy of 72.0%. Best results for both postprocessing methods were achieved in the vascular segments of the upper leg. In severely calcified segments, sensitivity, specificity, and accuracy stayed above 90% by the dual-energy bone removal technique, whereas the conventional bone removal technique showed a substantial decrease of sensitivity, specificity, and accuracy. DE-CTA is a feasible and accurate diagnostic method in the assessment of symptomatic peripheral arterial occlusive disease. Results obtained by DE-CTA are superior to the conventional bone removal technique and less dependent on vessel wall calcifications.

Variations of the superior sagittal sinus and bridging veins in human dissections and computed tomography venography.

OBJECTIVES The aim of the present study was to examine the superior sagittal sinus (SSS) and bridging veins (BVs) from an anatomical, neurosurgical and radiological perspective. METHODS Computed tomography venographies (CTVs) of 30 patients and 9 cadaveric dissections of human SSS were analyzed. RESULTS CTV and cadavers showed most BVs emptying into the SSS close by (±3 cm) and distal to the coronary suture (74% in CTV, 62% in cadavers). CONCLUSIONS Important anatomical information can be drawn from cerebral CTV for neurosurgical preoperative planning.

Abciximab does not prevent ischemic lesions related to cerebral angiography: a randomized placebo-controlled trial.

Background: To assess the efficiency of IIb/IIIa platelet receptor inhibition by abciximab in the prevention of silent embolism during digital subtraction angiography. Methods: In this randomized, double-blind, prospective study, pre- and postangiographic diffusion-weighted magnetic resonance imaging (DWI) of 184 participants was evaluated for the occurrence of silent embolism. Results: No significant relationship was found between the patients receiving abciximab before digital subtraction angiography (15 of 90; 16.7%) and patients in the placebo group (16 of 94; 17.0%) regarding postangiographic appearance of silent emboli (p = 0.9). Conclusions: IIb/IIIa receptor inhibition by abciximab does not diminish the occurrence of silent embolism during digital subtraction angiography. Our findings indicate that solid blood clots are not the origin of hyperintense lesions observed on DWI and enhance the role of alternative mechanisms.

Graph-Matching Based CTA

Separating bone, calcification, and vessels in computer tomography angiography (CTA) allows for a detailed diagnosis of vessel stenosis. This paper presents a new, graph-based technique that solves this difficult problem with high accuracy. The approach requires one native data set and one that is contrast enhanced. On each data set, an attributed level-graph is derived and both graphs are matched by dynamic programming to differentiate between bone, on one hand side, and vessel/calcification on the other hand side. Lumen and calcified regions are then separated by a profile technique. Evaluation is based on data from vessels of pelvis and lower extremities of elderly patients. Due to substantial calcification and motion of patients between and during the acquisitions, the underlying approach is tested on a class of difficult cases. Analysis requires 3-5 min on a Pentium IV 3 GHz for a 700 MByte data set. Among 37 patients, our approach correctly identifies all three components in 80% of cases correctly compared to visual control. Critical inconsistencies with visual inspection were found in 6% of all cases; 70% of these inconsistencies are due to small vessels that have 1) a diameter near the resolution of the CT and 2) are passing next to bony structures. All other remaining deviations are found in an incorrect handling of the iliac artery since the slice thickness is near the diameter of this vessel and since the orientation is not in cranio-caudal direction. Increasing resolution is thus expected to solve many the aforementioned difficulties.

Magnetic Resonance Imaging Flow Quantification of Non-Occlusive Excimer Laser-Assisted EC-IC High-Flow Bypass in the Treatment of Complex Intracranial Aneurysms

The patency of a bypass plays an important role in the postoperative recovery of patients especially when dealing with complicated intracranial aneurysms. In this study two-dimensional phase contrast magnetic resonance angiography (PC-MRA) was used to measure cerebral blood flow in 23 patients before extracranial-intracranial high-flow bypass surgery using the excimer laser-assisted non-occlusive anastomosis (ELANA) technique and in 15 patients following surgery. The results showed that PC-MRA is a suitable technique for assessing bypass patency and that with the ELANA technique the bypass has the capability of compensating the blood flow of an occluded internal carotid artery (ACI) in cases of complex aneurysms.

Graph-matching-based computed tomography angiography in peripheral arterial occlusive disease.

The objective of this study is to compare a graph-matching-based software and a conventional tool for postprocessing of computed tomography angiography (CTA) in correlation with the gold standard digital subtraction angiography. Sensitivity, specificity, accuracy, and interobserver agreement increased from 80.3% to 92.9%, from 69.1% to 92.4%, from 73.5% to 92.8%, and from 0.45 to 0.96, respectively, using the graph-matching-based technique. Graph-matching-based CTA increases sensitivity, specificity, accuracy, and interobserver agreement in comparison to a conventional bone elimination tool in the assessment of peripheral arterial occlusive disease.

Repeated MRI of a Patient with an Intramedullary Tumour and Implanted Cardiac Resynchronization Therapy Defibrillator (CRT-D)

The increasing life expectancy of the population of industrialised countries in combination with an increasing availability of novel cardiovascular implantable electronic devices (CIED) and therapeutic fields of application for these devices leads to an increasing number of (younger) patients with implanted CIed. This development is paralleled by an increasing availability of magnetic resonance (Mr) scanners and the increasing need of Mr imaging in a population continuously growing older [1, 2]. While for many medical questions the computed tomography (CT) provides an excellent diagnostic tool, subtle but relevant changes observed in neuroradiological disease processes frequently require the use of MrI to be detected and interpreted correctly [3]. exemplarily, for imaging of small structures such as the myelon, an MrI is the unrivalled diagnostic tool due to its high soft tissue contrast [4]. As MrI generally is considered a strict contraindication for patients with a CIed, the number of patients being denied an Mr study for this reason is increasing and for the year 2004 it has been estimated to be as high as 200,000 [1]. on the other hand, for patients with implanted pacemakers and implantable cardioverter defibrillator (ICD), several studies have demonstrated the relative safety of undergoing MrI (reviewed in [5]), whereas for patients with cardiac resynchronization therapy defibrillators (CRT–D) fewer studies exist [6]. since MrI in patients with most of the used CIed is not approved by the Food and drug Administration (FdA) but the aforementioned problem is likely to increase, in this article we (a) illustrate the feasibility to perform MrI of the head and spine in a patient with implanted CrT-d, (b) address possible complications and hazards that may be encountered and that need to be discussed with the patient prior to MrI, and (c) provide an overview of the precautionary measures that need to be taken before, during, and after MrI.

Diagnostic performance of different perfusion algorithms for the detection of angiographical spasm

PURPOSE To assess the diagnostic utility of different perfusion algorithms for the detection of angiographical terial spasm. METHOD During a 2-year period, 45 datasets from 29 patients (54.2±10,75y, 20F) with suspected cerebral vasospasm after aneurysmal subarachnoid hemorrhage were included. Volume Perfusion CT (VPCT), Non-enhanced CT (NCT) and angiography were performed within 6hours post-ictus. Perfusion maps were generated using a maximum slope (MS) and a deconvolution-based approach (DC). Two blinded neuroradiologists independently evaluated MS and DC maps regarding vasospasm-related perfusion impairment on a 3-point Likert-scale (0=no impairment, 1=impairment affecting <50%, 2=impairment affecting >50% of vascular territory). A third independent neuroradiologist assessed angiography for presence and severity of arterial narrowing on a 3-point Likert scale (0=no narrowing, 1=narrowing affecting <50%, 2=narrowing affecting>50% of artery diameter). MS and DC perfusion maps were evaluated regarding diagnostic accuracy for angiographical arterial spasm with angiography as reference standard. Correlation analysis of angiography findings with both MS and DC perfusion maps was additionally performed. Furthermor, the agreement between MS and DC and inter-reader agreement was assessed. RESULTS DC maps yielded significantly higher diagnostic accuracy than MS perfusion maps (DC:AUC=.870; MS:AUC=.805; P=0.007) with higher sensitivity for DC compared to MS (DC:sensitivity=.758; MS:sensitivity=.625). DC maps revealed stronger correlation with angiography than MS (DC: R=.788; MS: R=694;=<0.001). MS and DC showed substantial agreement (Kappa=.626). Regarding inter-reader analysis, (almost) perfect inter-reader agreement was observed for both MS and DC maps (Kappa≥981). CONCLUSION DC yields significantly higher diagnostic accuracy for the detection of angiographic arterial spasm and higher correlation with angiographic findings compared to MS.

Endovascular stentectomy using the snare over stent-retriever (SOS) technique: An experimental feasibility study

Feasibility of endovascular stentectomy using a snare over stent-retriever (SOS) technique was evaluated in a silicon flow model and an in vivo swine model. In vitro, stentectomy of different intracranial stents using the SOS technique was feasible in 22 out of 24 (92%) retrieval maneuvers. In vivo, stentectomy was successful in 10 out of 10 procedures (100%). In one case self-limiting vasospasm was observed angiographically as a technique related complication in the animal model. Endovascular stentectomy using the SOS technique is feasible in an experimental setting and may be transferred to a clinical scenario.