Flat-panel detector CT assessment in stroke to reduce times to intra-arterial treatment: A study of multiphase computed tomography angiography in the angiography suite to bypass conventional imaging.

BACKGROUND: Bypassing the emergency department and the computed tomography suite by directly transporting to the neuroangiography suite for imaging assessment and treatment may shorten reperfusion times while maintaining proper patient selection. OBJECTIVE: To determine whether flat-panel detector multiphase computed tomography angiography protocol is associated with reduced treatment times and a similar safety profile as the standard imaging protocol. METHODS: Single-center prospective study of consecutive patients with anterior circulation large vessel occlusion strokes transferred to our facility for consideration of endovascular therapy from May 2016 to December 2017. Those with basilar strokes and/or presenting to the emergency department were excluded. Patients were categorized into two groups: (1) flat-panel detector CT assessment in stroke to reduce times to intra-arterial treatment group, with patients transferred directly to the suite for multiphase computed tomography angiography; and (2) patients undergoing standard protocol including computed tomography ± computed tomography angiography/CT perfusion. The groups were matched for age, baseline National Institute of Health Stroke Scale, and pretreatment glucose. Baseline characteristics, time metrics, and outcomes were compared. RESULTS: Out of 419 patients who underwent endovascular therapy over the study period, 210 patients fit inclusion criteria, with 54 (25.7%) in the flat-panel detector CT assessment in stroke to reduce times to intra-arterial treatment group. After matching, 49 flat-panel detector CT assessment in stroke to reduce times to intra-arterial treatment/control pairs were generated and analyzed. Baseline characteristics were well balanced. Flat-panel detector CT assessment in stroke to reduce times to intra-arterial treatment patients had significantly shorter median door-to-puncture (33 [26.5-47] vs. 55 [44.5-66] min, p < 0.001), door-to-reperfusion (85 [57.5-115.5] vs. 110 [80-153], p = 0.005) and picture-to-puncture (18 [13.5-22.5] vs. 42 [32-47.5] min, p < 0.001) times. There were no differences in rates of successful reperfusion (modified thrombolysis in cerebral infarction 2b-3, 95.9% vs. 100%, p = 0.5), parenchymal hematomas type-2 (4.1% vs. 2%, p = 1.00), good outcome (90-day modified Rankin Scale 0-2, 44.9% vs. 40.8%, p = 0.68), and 90-day mortality (14.3% vs. 22.4%, p = 0.30). CONCLUSION: Directly transferring patients to angiography and using multiphase computed tomography angiography to determine the eligibility for endovascular therapy is safe and may result in a significant reduction in treatment times. Future larger studies are warranted.

Evaluation of a noise reduction imaging technology in iliac digital subtraction angiography: noninferior clinical image quality with lower patient and scatter dose.

PURPOSE: To determine whether equivalent-quality images can be obtained from digital subtraction angiography (DSA) of the iliac artery after implementation of a novel imaging technology that reduces patient and scatter x-ray dose. MATERIALS AND METHODS: Imaging using two randomly ordered DSA runs was performed in 51 adults scheduled for iliac artery angiography or intervention or both. One DSA run used standard acquisition chain and image processing algorithms (referred to as " reference DSA"), and the other DSA run used dose-reduction and real-time advanced image noise reduction technology (referred to as "study DSA"). The quality of each pair of runs, consecutively performed without changes in working projection or injection parameters, was independently rated by five radiologists blinded to the imaging technology used. Patient radiation dose was evaluated using air kerma and dose area product, and scatter dose was evaluated using three dosimeters (DoseAware, Philips Healthcare, Best, The Netherlands), located at fixed positions. RESULTS: Comparable image pairs were available in 48 patients. There were 44 patients undergoing treatment involving the common (n = 33) or external (n = 29) iliac arteries. Study DSA images were rated as equal to or better than reference DSA images for 96% of comparisons, with an average overall agreement among raters of 0.93 (95% confidence interval, 0.65-0.96). Mean patient radiation dose (n = 48) and scatter dose rate for the three dosimeters (n = 50) was 83% ± 5 and 69% ± 10 lower, respectively, using the study technology (P < .001). CONCLUSIONS: Iliac artery DSA performed using a dose-reduction and real-time advanced image noise reduction technology results in image quality that is noninferior to conventional DSA but with significantly lower patient and scatter radiation exposure (P < .001).

Image guidance for endovascular repair of complex aortic aneurysms: comparison of two-dimensional and three-dimensional angiography and image fusion.

PURPOSE: To evaluate the feasibility of image fusion (IF) of preprocedural arterial-phase computed tomography with intraprocedural fluoroscopy for roadmapping in endovascular repair of complex aortic aneurysms, and to compare this approach versus current roadmapping methods (ie, two-dimensional [2D] and three-dimensional [3D] angiography). MATERIALS AND METHODS: Thirty-seven consecutive patients with complex aortic aneurysms treated with endovascular techniques were retrospectively reviewed; these included aneurysms of digestive and/or renal arteries and pararenal and juxtarenal aortic aneurysms. All interventions were performed with the same angiographic system. According to the availability of different roadmapping software, patients were successively placed into three intraprocedural image guidance groups: (i) 2D angiography (n = 9), (ii) 3D rotational angiography (n = 14), and (iii) IF (n = 14). X-ray exposure (dose-area product [DAP]), injected contrast medium volume, and procedure time were recorded. RESULTS: Patient characteristics were similar among groups, with no statistically significant differences (P ≥ .05). There was no statistical difference in endograft deployment success between groups (2D angiography, eight of nine patients [89%]; 3D angiography and IF, 14 of 14 patients each [100%]). The IF group showed significant reduction (P < .0001) in injected contrast medium volume versus other groups (2D, 235 mL ± 145; 3D, 225 mL ± 119; IF, 65 mL ± 28). Mean DAP values showed no significant difference between groups (2D, 1,188 Gy · cm(2) ± 1,067; 3D, 984 Gy · cm(2) ± 581; IF, 655 Gy · cm(2) ± 457; P = .18); nor did procedure times (2D, 233 min ± 123; 3D, 181 min ± 53; IF, 189 min ± 60; P = .59). CONCLUSIONS: The use of IF-based roadmapping is a feasible technique for endovascular complex aneurysm repair associated with significant reduction of injected contrast agent volume and similar x-ray exposure and procedure time.

Live MR angiographic roadmapping for uterine artery embolization: a feasibility study.

PURPOSE: To assess the feasibility of live magnetic resonance (MR) angiography roadmapping guidance for uterine artery (UA) embolization (UAE) for fibroid tumors. MATERIALS AND METHODS: Twenty patients underwent UAE with live MR angiographic roadmapping. The pre-acquired MR angiography scan was coregistered with the live intraprocedural fluoroscopy stream to create a visual roadmap to direct the microcatheter during UAE. Patient radiation dose, as measured by dose-area product (DAP), procedure time, contrast medium volume, and fluoroscopy time, was recorded. For the first 10 patients, an additional parameter of contrast medium volume needed to catheterize each UA was recorded. RESULTS: In all 20 patients (40 UAs), the MR angiography overlay on live fluoroscopy was accurate and allowed for successful catheterization of the UA, resulting in a technical success rate of 100%. In the subset of the initial 20 UAs (ie, the first 10 patients) in which this data point was recorded, 17 (85%) were successfully catheterized with no iodinated contrast medium at all, by purely relying on the MR angiography roadmap. Mean procedure time was 45 minutes (range, 30-99 min), mean contrast agent dose was 75 mL (range, 46-199 mL), and mean DAP was 155 Gy · cm(2) (range, 37-501 Gy · cm(2)). CONCLUSIONS: Live MR angiographic roadmapping is feasible and accurate for catheter guidance during UAE.

Three-dimensional rotational angiography is preferable to conventional two-dimensional techniques for uterine artery embolization.

PURPOSE: We aimed to investigate the potential benefits of three-dimensional rotational angiography (3DRA) compared to two-dimensional (2D) roadmapping to visualize the uterine artery (UA) origins during uterine artery embolization (UAE) procedures. MATERIALS AND METHODS: Sixty-three UAE cases performed under 3DRA guidance were reviewed retrospectively to determine if there was an optimal angiographic projection angle for identifying UA origin. Digital subtraction angiogram (DAS)-like images of the pelvic vessels were generated from the 3DRA scans at six different angles: left anterior oblique (LAO) 25°, 35°, 45°; and right anterior oblique (RAO) 25°, 35°, 45°. Two experienced interventional radiologists assessed if these angles could effectively serve as a roadmap to guide catheterization of the UA. Assessment was validated against original 3DRA scans to determine the percentage of true and false positives. RESULTS: No single projection angle was found that could consistently be utilized for UA catheterization. The projection angles used during 3D roadmapping for both the left and right UA showed two clusters with both a wide spread: RAO 20° to 50° and LAO 20° to 50°. More than 50% of the DSA-like images at RAO and LAO 45° appeared to be adequate for UA catheterization, but validation against the 3DRA revealed 28% of these images were suboptimal and deceptive, due to unappreciated overlapping vessels. CONCLUSION: No standard projection angles can be recommended with 2D roadmapping to consistently visualize UA origin. The 3DRA can be as a useful tool for UAE to achieve reliable and consistent visibility of the UA origin.

Intervertebral disk nutrition: a review of factors influencing concentrations of nutrients and metabolites.

The biomechanical behavior of the intervertebral disk ultimately depends on the viability and activity of a small population of resident cells that make and maintain the disk's extracellular matrix. Nutrients that support these cells are supplied by the blood vessels at the disks' margins and diffuse through the matrix of the avascular disk to the cells. This article reviews pathways of nutrient supply to these cells; examines factors that may interrupt these pathways, and discusses consequences for disk cell survival, disk degeneration, and disk repair.

Notochordal intervertebral disc cells: sensitivity to nutrient deprivation.

OBJECTIVE: The nucleus pulposus (NP) of the intervertebral disc develops from the notochord. Humans and other species in which notochordal cells (NCs) disappear to be replaced by chondrocyte-like mature NP cells (MNPCs) frequently develop disc degeneration, unlike other species that retain NCs. The reasons for NC disappearance are unknown. In humans, the change in cell phenotype (to MNPCs) coincides with changes that decrease nutrient supply to the avascular disc. We undertook this study to test the hypothesis that the consequent nutrient stress could be associated with NC disappearance. METHODS: We measured cell densities and metabolic rates in 3-dimensional cultures of porcine NCs and bovine MNPCs, and we determined survival rates under conditions of nutrient deprivation. We used scanning electron microscopy to examine end plate porosity of discs with NCs and those with MNPCs. Nutrient-metabolite profiles and cell viability were calculated as a function of cell density and disc size in a consumption/diffusion mathematical model. RESULTS: NCs were more active metabolically and more susceptible to nutrient deprivation than were MNPCs. Hypoxia increased rates of glycolysis in NCs but not in MNPCs. Higher end plate porosity in discs with NCs suggested greater nutrient supply in keeping with higher nutritional demands. Mathematical simulations and experiments using an analog disc diffusion chamber indicated that a fall in nutrient concentrations resulting from increased diffusion distance during growth and/or a fall in blood supply through end plate changes could instigate NC disappearance. CONCLUSION: NCs demand more energy and are less resistant to nutritional stress than MNPCs, which may shed light on the fate of NCs in humans. This provides important information about prospective NC tissue engineering approaches.

An in vitro organ culturing system for intervertebral disc explants with vertebral endplates: a feasibility study with ovine caudal discs.

STUDY DESIGN: Whole ovine caudal intervertebral discs with vertebral endplates were cultured under uniaxial diurnal loading for 7 days. OBJECTIVES: To establish and characterize an organ culture system for intervertebral discs, in which disc cells may be "maintained" in their native three-dimensional environment under load. SUMMARY OF BACKGROUND DATA: In vitro culturing of entire discs with preserved biologic and structural integrity would be a useful model to study the effects of nutrition and mechanical loading. METHODS: To maintain endplate permeability, sheep were systemically anticoagulated before death and their caudal vasculature was evacuated with saline postmortem. The first 4 caudal discs were explanted with their adjacent endplates and cultured in bioreactors under uniaxial diurnal loading (0.2 MPa for 8 hours and 0.8 MPa for 16 hours) for 4 or 7 days. Solute transport into the center of the disc was measured after 4 days of culture using a low molecular weight fluorescent marker. Cell viability, glycosaminoglycan synthesis rate, and gene expression profile were measured after 7 days of culture and compared with fresh tissue. RESULTS: Fluorescent images showed that solutes could diffuse into the disc under both static and diurnal loading, but penetration through the endplate increased with diurnal loading. Cell viability and glycosaminoglycan synthesis rates remained unchanged after 7 days of culture. Expression of catabolic genes was significantly up-regulated, whereas anabolic genes tended to be down-regulated after 7 days. CONCLUSIONS: With this novel preparation and culturing technique, endplate permeability could be maintained, which allowed culturing of intact disc explants with endplates for up to 7 days.

Nutrient supply and intervertebral disc metabolism.

The metabolic environment of disc cells is governed by the avascular nature of the tissue. Because cellular energy metabolism occurs mainly through glycolysis, the disc cells require glucose for survival and produce lactic acid at high rates. Oxygen is also necessary for cellular activity, although not for survival; its pathway of utilization is unclear. Because the tissues are avascular, disc cells depend on the blood supply at the margins of the discs for their nutrients. The nucleus and inner anulus of the disc are supplied by capillaries that arise in the vertebral bodies, penetrate the subchondral bone, and terminate at the bone-disc junction. Small molecules such as glucose and oxygen then reach the cells by diffusion under gradients established by the balance between the rate of transport through the tissue to the cells and the rate of cellular demand. Metabolites such as lactic acid are removed by the reverse pathway. The concentrations of nutrients farthest from the source of supply can thus be low; oxygen concentrations as low as 1% have been measured in the discs of healthy animals. Although gradients cannot be measured easily in humans, they can be calculated. Measured concentrations in surgical patients are in agreement with calculated values.