Introduction: Measurement of local hemodynamic behavior is useful for assessing the pathology of carotid stenosis. In this study, we explore a novel method using two-dimensional digital subtraction angiography (2D DSA) to provide time-dependent pressure data. We performed comparative validation with computational fluid dynamics (CFD) and flow guidewire measurements as reference methods. Methods: A silicone phantom model of a carotid stenosis was prepared, filled with physiological saline, and connected to a flow pump (Vascular Simulations, LLC Left Heart Replicator) applying pulsatile flow. The stenosis model narrowed from a diameter of 1.37 cm to 0.58 cm for a length of 0.64 cm (NASCET=40%). Iodinated contrast media was injected, and time dependent pressure profiles at four regions of interest: 2 cm proximal to the stenosis, proximal end of the stenosis, distal end of the stenosis and 2 cm distal to the stenosis were derived from contrast intensity (I) obtained from 2D DSA background-subtracted intensity plots using previously published PVEC software. A Volcano flow guidewire sensor was utilized at the same four locations to collect flow data. Pulsatile CFD flow analysis was performed to extract flow data. Results: DSA PVEC contrast analysis allowed observation of distinct flow pulsatility. At 30fps, strong agreement of DSA contrast waveform matching CFD and guidewire flow measurements was found at the distal end of the stenosis over a period of linear contrast increase (constant dI/dt). Bland-Altman analysis was used to compare derived pressure with the reference methods over 3.5 cardiac cycles, from 5.9 s to 8.7 s after the initial injection of contrast. 2D DSA-derived pressure showed a mean departure of -10.24% (std. dev 14.65%) pressure obtained from CFD analysis, and a mean departure of -15.32% (std. dev 14.24%) from guidewire measurements for the duration. Conclusion: A novel computational approach suggests 2D DSA can provide real-time results to approximate carotid flow from 2D DSA. We showed using this novel approach the flow data is comparable with guide wire and CFD methods. Future experiments may allow it to provide a supplementary, non-invasive means to examine local hemodynamic behavior that is relevant to the evaluation of carotid stenosis.
Background and Purpose— Acceleration of intra-aneurysmal clot organization and fibrosis may be a solution to preventing aneurysm recanalization after endovascular treatment. The purpose of this study was to evaluate the short-term efficacy and long-term safety of the new Matrix coil system. Methods— Matrix coils consist of thin platinum coils covered with a bioabsorbable, polymeric material (polyglycolic acid/lactide). Fifty-two experimental aneurysms were created in 26 swine. All of the aneurysms were tightly packed with Matrix or Guglielmi detachable coils (GDC). Comparative angiographic and histopathologic data were analyzed at 2 weeks (n=14), 3 months (n=6), and 6 months (n=6) after embolization. Results— Three aneurysms treated with GDC ruptured despite tight packing. No recanalization or rupturing was observed in the aneurysms embolized with Matrix coils. At 14 days after embolization, the aneurysms treated with Matrix coils exhibited a more extensive area of organized thrombus when compared with the aneurysms treated with GDC (87% versus 75%, P =0.008, n=11). At 3 months, both Matrix and GDC-treated aneurysms demonstrated complete clot organization. Neck tissue thickness was higher in Matrix-treated aneurysms at 14 days and 3 months, but not at 6 months. No untoward parent artery stenosis was observed in aneurysms treated with Matrix during follow-up. The angiographic cross-sectional area of the Matrix-treated aneurysms was smaller than those treated with GDC at the 3 months. Conclusion— Matrix accelerated aneurysm fibrosis and neointima formation without parent artery stenosis. The Matrix system might prevent aneurysmal recanalization after endovascular treatment of cerebral aneurysms.
Background: TICI scores are routinely used to measure reperfusion on angiography after endovascular therapies for acute stroke. Reperfusion may also be quantified by Tmax parameter changes on serial perfusion MRI before and after treatment. Such definitions of reperfusion used in trials may vary and we therefore investigated the correlation between TICI and quantification of Tmax changes on serial MRI in proximal middle cerebral artery (MCA) stroke cases treated with endovascular therapy. Methods: Consecutive acute ischemic stroke patients treated with endovascular therapy for proximal or M1 MCA occlusions with serial perfusion MRI at baseline and 3-6 hours after treatment were analyzed. TICI scores were noted for reperfusion on angiography. Reperfusion on serial MRI was separately defined as interval volume of Tmax>6s lesion size, dichotomous change by > 70% reduction in Tmax>6s, and voxel-wise changes across all Tmax values. Results: 57 stroke patients (mean age 64±20 years, 68% female) with M1 MCA occlusions imaged with perfusion MRI both before and after treatment with endovascular therapy were studied. TICI angiographic outcomes included 8 TICI 0, 4 TICI 1, 22 TICI 2a, 22 TICI 2b and 1 TICI 3. Both the interval volume of Tmax>6s lesion size and voxel-wise changes across all Tmax values varied extensively. Dichotomous reduction in Tmax>6s lesion volume by 70% was noted in only 12.9% of cases, with reduction by 60% in 19.4%, and by 50% in 30.6%. TICI reperfusion did not correlate with either: interval volume of Tmax>6s lesion size, dichotomous change by > 70% reduction in Tmax>6s, or voxel-wise changes across all Tmax values. Even when only TICI 2a/2b/3 or TICI 2b/3 cases were analyzed, no correlation could be established between the TICI angiographic measure of reperfusion at post-procedure with the change in Tmax lesion from baseline to 3-6 hours after revascularization. Conclusions: Reperfusion measured by TICI at angiography and changes in Tmax on serial perfusion MRI provide distinct information, likely reflecting heterogeneity and different vascular phases (arterial vs. microcirculation). Determining the clinical impact of such reperfusion measures on recovery after stroke remains paramount.
The vascular anatomy of the spinal cord is reviewed. This serves as a basis not only to understand the pathophysiology of spinal cord vascular malformations but also to logically classify these lesions. Imaging studies required to identify and categorize these vascular malformations are also described.
Introduction: Although image-derived parameters such as wall shear stress (WSS), flow rate (FR), aspect ratio (AR), size ratio (SR), and non-sphericity index (NSI) were previously linked to risks of intracranial aneurysm (IA) growth, findings across studies have been inconsistent. Here, we revisit existing hemodynamic and morphological metrics and compare them between stable and growing IAs. We hypothesize that some may differentiate growing and stable trajectories of IAs. Methods: Unruptured IA cases between 2018-2020 were identified from UCLA Medical Center electronic medical records, with follow-up data used to determine growth status. From CTA/MRA images, models of 16 stable and 20 growing unruptured IA cases were reconstructed. Aneurysm diameter, height, neck width, surface area, volume, parent artery diameter, AR, SR, NSI, volume ratio, and surface area ratio were calculated. With data from hemodynamic simulations, we also measured FR and WSS. To capture spatial variations in hemodynamics, we calculated location-dependent mean deviation of WSS and FR at 3 locations within an aneurysm: neck, body, and dome. Pearson chi-square tests were used to compare background variables between groups. MANOVA was employed to compare the index values between stable and growing IAs. Results: Variables including location, diameter, race, history of smoking, and SAH were not significantly different between groups (p>>.05). Gender (p=0.06) and multiplicity (p=0.06) approached significance. Among the size-related and morphological parameters described above, only IA height (3.07±1.94mm vs. 5.49±3.61mm, p=0.03), neck width (4.93±1.42mm vs. 7.14±3.78mm, p=0.04), and size ratio (1.40±0.62 vs. 2.27±1.27, p =0.02) were significantly different (stable vs. growing, respectively). Growing IA had significantly higher FR spatial variation (0.43±0.35 vs. 0.75±0.44; p=0.03) and WSS spatial variations (0.24±0.20 vs. 0.49±0.28; p=0.008). Conclusions: Our findings support that location-dependent hemodynamic variations and SR may be potential risk factors of IA growth. Upon validation in larger studies, these parameters may aid in early identification of incidentally found IAs’ trajectories.
Over the past few years , major advances in the develop ment of new microcatheter systems have greatly improved the safety and efficacy of therapeutic endovascular tech niques (1 -4). The ideal embolization catheter should have the following characteristics: simplicity of use, ability to negotiate tortuous curves with a minimum of manipulations and without trauma to the artery or induction of spasm, outer diameter small enough that the physical presence of the catheter in the vessel is not occlusive, and inner diameter large enough to permit a choice of embolic agents of various types and sizes. We present our experience with the Progressive Suppleness Pursil Catheter,* which helps fulfill these criteria. With the 3-French/1 .8-French microcatheter, tortuous ves sels can be catheterized and good quality superselective angiograms can be obtained (Fig . 2). Bench experiments showed that attempting wire manipulation can result in sep aration of the Pursil catheter from the proximal 3-French shaft because of friction between wire and catheter; therefore, this maneuver should be attempted only with extreme caution or should not be attempted at all. Two or three separate injec tions per catheter may be performed providing the following steps are followed: a homogeneous mixture of tantalum pow der (1 g) and iophendylate (0 .3-1 ml , depending on the polymerization time desired) should be obtained by gentle swirling before addition of 1 ml of isobutyl 2-cyanoacrylate (bucrylate) (IBCA); a 25cgauge needle should be used to aspirate the supernatant portion of the IBCA-iophendylate tantalum mixture in order to prevent loading of clumps (which can block the microcatheter) into the embolization syringe (1- ml Luer lock); with the microcatheter loaded with 5% dextrose in water solution (D 5W) , no more than 0.3-ml IBCA-iophen dylate-tantalum mixture should be initially loaded via a three way stopcock; then the mixture should be pushed through using either a 1- or 3-ml syringe containing D5W; after remov ing the stopcock and syringes, at least 5 ml of DsW should be flushed through the catheter. Despite these precautions, deposition of small amounts of tantalum powder on the inner wall will cause progressive narrowing of the catheter lumen; this increases the force required for injection and can even tually result in occlusion or even rupture of the catheter near its junction with the 3-French segment. Hence, the total number of IBCA injections should not exceed three per cath eter if the descri bed steps for IBCA preparation are followed (if they are not followed, only one injection of IBCA should be performed per catheter).
