In our phantom study, IA-DSA was the only examination to predict accurately degrees of stenosis compared with the known stenosis diameters. The results of the IV-ACT measurements were comparable with those of IA-DSA. Multidetector computed tomographic angiography was less accurate in the quantification of stenosis, usually overestimating ISR.
BACKGROUND AND PURPOSE: Endovascular treatment of intracranial aneurysms has relevantly changed over the past decades. Multiple new devices such as intrasaccular flow diverters have broadened the treatment spectrum but require very exact aneurysm sizing. In this study, we investigated multidetector and flat panel angiographic CT and digital subtraction imaging as well as different postprocessing methods (multiplanar reconstruction, volume-rendering technique, 3D DSA, and conventional 2D angiography) for their ability to exactly size 2 aneurysm models. MATERIALS AND METHODS: Two aneurysm models with known aneurysm sizes were placed inside a human skull. After injection of iodine contrast media, imaging was performed using a 128-slice CT scanner or an Artis Q biplane angiosuite, respectively. Aneurysms were measured for width, neck, and height, and the mean difference from the known sizes was calculated for each technique. The technique with the most exact measurement was defined as the criterion standard. We performed Bland-Altman plots comparing all techniques against the criterion standard. RESULTS: Angiograms adjusted according a previous 3D run with a short object-to-detector distance resulted in the most exact aneurysm measurement: Ϫ0.07 Ϯ 0.61 mm for aneurysm 1 and 0.17 Ϯ 0.39 mm for aneurysm 2. Measurements of conventional DSA images were similar, and CT-based images were significantly inferior to the criterion standard. CONCLUSIONS: 2D DSA with a short objective-to-detector distance adjusted according to a previous 3D run resulted in the most exact aneurysm measurement and should therefore be performed before all endovascular aneurysm treatments. ABBREVIATIONS: FDCTA ϭ flat panel detector CTA; MDCTA ϭ multidetector row CTA; VRT ϭ volume-rendering technique
Background
Flat detector CT – angiography (FDCTA) has become a valuable imaging tool in post- and peri-interventional imaging after neurovascular procedures. Metal artifacts produced by radiopaque implants like clips or coils still impair image quality.
Methods
FDCTA was performed in periprocedural or follow-up imaging of 21 patients, who had received neurovascular treatment. Raw data was sent to a dedicated workstation and subsequently a metal artifact reduction algorithm (MARA) was applied. Two neuroradiologists examined the images.
Results
Application of MARA improved image appearance and led to a significant reduction of metal artifacts. After application of MARA only 8 datasets (34% of the images) were rated as having many or extensive artifacts, before MARA 15 (65%) of the images had extensive or many artifacts. Twenty percent more cases of reperfusion were diagnosed after application of MARA, congruent to the results of digital subtraction angiography (DSA) imaging. Also 3 (13% of datasets) images, which could not be evaluated before application of MARA, could be analyzed after metal artifact reduction and reperfusion could be excluded.
Conclusion
Application of MARA improved image evaluation, reduced the extent of metal artifacts, and more cases of reperfusion could be detected or excluded, congruent to DSA imaging.
Flat panel detectors have revolutionized tomographic imaging in the angio suite. Recent developments in hardware and software have improved soft tissue resolution and acquisition time even further, enabling soft-tissue and perfusion imaging within the angio suite. The so called "one-stop-shop" stroke imaging with flat panel detector computed tomography (FDCT) will significantly improve door to groin times and probably have an impact on patient outcome. In the presented case a patient underwent multidetector CT (MDCT) to exclude hemorrhage, then MDCT angiography (MDCTA) to identify the occluded vessel, and MDCT perfusion (MDCTP) for penumbra imaging. Patient's symptoms significantly improved during transport to the angiography suite. Thus, prior to intervention, multimodal FDCT with vessel and perfusion imaging was acquired and ultimately led to cancelation of the interventional therapy. In this clinical scenario, multimodal FDCT imaging can provide quick answers and eliminate the risk of an invasive angiography in cases of reperfusion prior to mechanical thrombectomy.
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