Background/Objectives: To assess free-breathing, dynamic radial magnetic resonance angiography (MRA) for detecting endoleaks post-endovascular aortic repair (EVAR) in cases with inconclusive computed tomography angiography (CTA). Methods: This prospective single-center study included 17 participants (mean age, 70 ± 9 years; 13 males) who underwent dynamic radial MRI (Golden-angle RAdial Sparse Parallel-Volumetric Interpolated BrEath-hold, GRASP-VIBE) after inconclusive multiphasic CT for the presence of endoleaks during the follow-up of EVAR-treated abdominal aortic aneurysms. CT and MRI datasets were independently assessed by two radiologists for image quality, diagnostic confidence, and the presence/type of endoleak. Statistical analyses included interrater and intermethod agreement, and diagnostic performance (sensitivity, specificity, area under the curve (AUC)). Results: Subjective image analysis demonstrated good image quality and interrater agreement (k ≥ 0.6) for both modalities, while diagnostic confidence was significantly higher in MRA (p = 0.03). There was significantly improved accuracy for detecting type II endoleaks on MRA (AUC 0.97 [95% CI: 0.87, 1.0]) compared to CTA (AUC 0.66 [95% CI: 0.41, 0.91]; p = 0.03). Although MRA demonstrated higher values for sensitivity, specificity, AUC, and interrater agreement, none of the other types nor the overall detection rate for endoleaks showed differences in the diagnostic performance over CT (p ≥ 0.12). CTA and MRA revealed slight to moderate intermethod concordance in endoleak detection (k = 0.3–0.64). Conclusions: The GRASP-VIBE MRA characterized by high spatial and temporal resolution demonstrates clinical feasibility with good image quality and superior diagnostic confidence. It notably enhances diagnostic performance in detecting and classifying endoleaks, particularly type II, compared to traditional multiphase CTA with inconclusive findings.
Background Sufficient radiopacity of stents is a prerequisite for safe interventions and minimization of the radiation dose for the patient and the interventionist. Modern nitinol stents are considered less radiopaque compared to formerly used stents. Purpose To evaluate the objective detection rate (ODR) and the subjective radiopacity score (SRS) of four self-expanding nitinol stents with their markers on a phantom human pelvis. Material and Methods We evaluated the ODR (as a percentage of correctly identified stents) and the SRS (on a scale from 0 = not visible to 4 = excellent visibility) for four self-expanding nitinol stents (SinusSuperflex, SMART, Luminexx, Zilver) with 8 mm diameter and 40 mm length. Stents were placed on a phantom human pelvis and images of the stents were taken in four different positions (right and left lumbosacral joint and near the right and left limbus acetabuli) using the following modes: spotfilm, pulsed fluoroscopy (4, 7.5, 15, and 30 pulses/min) and at three different digital magnification modes. Dose area products (DAPs) were assessed. Results ODR and SRS, respectively, were significantly increased for the SMART stent compared to all other tested stents ( P < 0.05): SMART 93.53% and 2.43, SinusSuperflex 90.81% and 2.21, Luminexx 90.39% and 2.20, and Zilver 89.28% and 2.21. ODR was significantly reduced in position 3 where the bone overlap was more pronounced for all stents (detection rates 77.14-79.56%). An increase in magnification significantly improved the ODR and SRS for all stents (70.33-99.25% and 1.07-3.28, respectively, P < 0.05). Increased pulsing frequency did not improve the ODR of the various stents but did increase the DAP. Conclusion The SMART stent had the best overall performance. In the presence of bone overlap, all self-expanding nitinol stents had poor results. Increased pulsing frequency did not improve ODR or SRS but did increase the DAP. Use of digital magnification modes had no effect on DAP increasing ODR and SRS.
The objective of this study was to compare the performance and radiation doses of a flat-panel detector (FPD) angiography machine with an image intensifier (II) angiography machine.Images of four nitinol stents (Sinus-SuperFlex, SMART, Luminexx, and Zilver stents) in a phantom of a human pelvis were acquired on an FPD system (Axiom Artis) and an II system (Fluorospot TOP) using the following modes: spot-film, continuous fluoroscopy (4, 7.5, 15, and 30 pulses/s), and three amplification modes. Objective stent detection rates and subjective radiopacity scores (scale: 0 [not visible] to 4 [excellent visibility]) were calculated. The radiation doses evaluated by the respective machines were compared.Over all modes and stents, the mean objective correct stent detection rates and mean subjective radiopacity scores were 89.49% and 1.81, respectively, for the Axiom Artis and 91.00% and 2.26 for the Fluorospot TOP. The stent detection rates over all modes for the SMART and Luminexx stents were better using the Axiom Artis machine (97.61% vs 93.55% and 98.28% vs 90.41%, respectively) and those for the Sinus-SuperFlex and Zilver stents were better using the Fluorospot TOP machine (90.83% vs 83.56% and 89.29% vs 80.50%). The subjective radiopacity scores of stent visibility were worse for the Axiom Artis than the Fluorospot TOP for all stents except the Luminexx stent (mean score, 2.34 vs 2.21, respectively). The objective stent detection rates and subjective radiopacity scores improved using the spot-film mode and with raising amplification, whereas increases in the fluoroscopy pulsing frequency did not improve stent detection rates or radiopacity scores for either machine. The radiation doses at continuous fluoroscopy were approximately 90% higher for the Axiom Artis than for the Fluorospot TOP (2.60 vs 1.41 μGy/m(2) at 30 pulses/s, respectively).The objective correct stent detection rates were similar for both machines with differences in detection for the respective stents. The subjective radiopacity scores were almost always better for the Fluorospot TOP machine. Also, the Axiom Artis machine generated approximately 90% higher radiation doses in fluoroscopy. For both machines, using a higher fluoroscopy pulsing frequency had no positive effect on objective correct stent detection rates or subjective radiopacity scores.
