RPS 215 - Advances in peripheral imaging

Author Block: J. Csőre, A. Crichton, B. Benfor, C. Karmonik, T. L. Roy; Houston, TX/US
Purpose: Traditional animal models often fail to capture the complexity of peripheral artery disease (PAD) lesions, leading to a gap between preclinical and clinical research in percutaneous vascular interventions (PVI). To address this, we developed a human amputated limb model combined with a proprietary MRI-histology protocol for detailed plaque characterization and simulation of PVI procedures, assessing lesion-specific device impact on the vessel wall.
Methods or Background: Amputated limbs from end-stage PAD patients were scanned using 3T or 7T MRI, incorporating Ultrashort Echo Time and T2-weighted sequences to differentiate hard (collagen/calcium) and soft (fat/thrombus/smooth muscle) plaque components. PVI procedures were simulated in a hybrid operating room, targeting identified lesions. Device testing included balloon angioplasty, lithotripsy, atherectomy, drug-coated balloons, and novel wires/catheters. Vessel impact was evaluated intraprocedurally using intravascular ultrasound, followed by post-procedure micro-CT and 9.4T MRI. Histopathological analysis was performed with Movat’s and H&E stains.
Results or Findings: A total of 70 amputated limbs were collected, yielding 133 target lesions and 2500 histologic cross-sections. Key findings include:
1. Validation of the MRI protocol and human amputated limb model.
2. Successful testing of vessel preparation devices, showing plaque disruption and dissection in calcified lesions.
3. Correlation of chronic total occlusion crossing success with pre-intervention MRI histology scoring.
4. Identification of calcified lesions as barriers to effective drug delivery.
5. Collaboration with industry for device development and testing.
Conclusion: This human cadaveric model offers a unique platform for PAD research, providing detailed insights into plaque morphology and PVI device performance. By correlating plaque characteristics with procedural outcomes, it enables precise device testing and fosters innovation in vascular interventions. This model informs clinical decision-making, enhances new technology design, and guides personalized treatment strategies for PAD patients.
Limitations: Single-center study, small cohort
Funding for this study: Jerold B. Katz Academy of Translational Science (project ID 15790002, recipient: Trisha Roy); American Heart Association Transformational Award (project ID: 17590004, recipient: Trisha Roy); National Institutes of Health Research Project grant (R01) (award ID: R01HL174587, recipient: Trisha Roy)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Institutional Review Board under study ID PRO00027258.

Author Block: J. Xin, H. Yu, L. Zhu; Shang Hai/CN
Purpose: Objective: This study seeks to investigate the differences in image quality and radiation exposure between an advanced precision scanning technique and traditional scanning methods in 320-slice computed tomography angiography (CTA) of the lower limb
Methods or Background: Methods: A cohort of 89 patients with suspected lower limb a arteryial disease, who underwent CTA examination at our institution, were randomly allocated to either group A or group B. In group A,low-dose testing was first used. TS was obtained by subtracting the time to peak of the dorsalis pedis artery T2 and the time to peak of the main abdominal artery T1;the formal scan began at T1 + 4 seconds,and the scan was completed after adjusting the entire acquisition time to TS by the variable pitch method.Group B was scanned using standard pitch.The statistical analysis involved the assessment of image quality,radiation dose, and contrast agent dosage.
Results or Findings: Results:Both subjective and objective evaluations demonstrated superior image quality of lower extremity artery in group A(all P<0.001).The subjective score for group A demonstrated a significant 21% increase compared to that of group B, particularly in the assessment of ankle and dorsum images (4.32±0.79 vs. 3.57±0.94).In terms of patients' radiation dose and contrast agent dosage, group A exhibited a 16.23% reduction in radiation dose and a 12.28% reduction in contrast agent dosage compared to group B, respectively (both P< 0.001).
Conclusion: Conclusion: The implementation of VHP technology in lower extremity artery CTA scanning facilitates enhanced visualization of distal blood vessels and improves overall image quality, meanwhile effectively reducing radiation exposure and contrast agent consumption, which presents substantial clinical value.
Limitations: The sample size is relatively small and warrants expansion for further validation of the derived conclusions.
Funding for this study: Young Scientists Fund of the National Natural Science Foundation of China (82302188)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: No:2019tjdx123

Author Block: K. Qi, J. Liu; Zhengzhou/CN
Purpose: To validate the feasibility of using bolus tracking with a patient-tailored post-trigger delay (PTD) in run-off CTA and to compare image quality with that using a fixed PTD.
Methods or Background: Participants undergoing run-off CTA with bolus tracking were prospectively assigned at random, cohort A comprised 30 participants with a fixed 10-second PTD and cohort B comprised 30 participants with a patient-tailored PTD. The attenuation of abdominal and lower limb arteries was measured in 11 different anatomical positions in one leg and divided into four vascular segments according to the anatomical location: aortoiliac, femoropopliteal, tibioperoneal and foot. The mean attenuation, SNR and CNR of each vessel segment were calculated. Two readers rated subjective image quality. Two-way analysis of variance was used to assess the mean attenuation of four vascular segments. Sidak's multiple comparison was used to determine differences in attenuation between the two cohorts and at each anatomical location within each cohort. Mann-Whitney test was used to determine SNR and CNR between two groups, while the chi-square test compared subjective image quality scores.
Results or Findings: Cohort B using new bolus tracking algorithm predicts the mean patient-tailored PTD of 12 ± 1.8 s. The demographic and frequency of PAD revealed no statistically significant differences. Cohort B showed greater attenuation of tibioperoneal (432±76 HU vs 364±69HU, p=0.001) and foot (369±79 HU vs 281±77HU, p=0.001) segments. SNR (p<0.002), CNR(p<0.002) and subjective image quality (excellent or good image quality, 96.7% vs 74.3%, p=0.038) were higher in cohort B than in the fixed cohort.
Conclusion: Bolus tracking with a patient-tailored PTD provides reliable scan timing, resulting in improved image quality and optimized vessel opacification in run-off CTA .
Limitations: Further research is needed on the relationship between frequency of PAD and PTD.
Funding for this study: The Science and Technology Research Project of Henan Provincial Health Commission (No. 212102310142)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Ethics Committee of Zhengzhou University

Author Block: Ö. Altun, A. Dablan, M. Sam Özdemir, M. Karagülle, M. Cingöz, M. F. Arslan; Istanbul/TR
Purpose: To evaluate the utility of shear wave elastography (SWE) in distinguishing between acute and subacute thrombi in thrombosed dialysis arteriovenous fistulas (AVFs).
Methods or Background: This retrospective study analyzed 32 dialysis patients with thrombosed AVFs treated between June 2022 and June 2024. All patients underwent Doppler ultrasound and SWE to determine thrombus characteristics. Based on ultrasound findings and clinical history, patients were categorized into acute or subacute thrombus groups. Thrombus stiffness was quantified using SWE in terms of average, median, and maximum kilopascal (kPa) values.
Results or Findings: The study included 16 patients with acute thrombi and 16 with subacute thrombi. SWE measurements revealed significantly higher stiffness values in subacute thrombi compared to acute thrombi (p < 0.001). A strong positive correlation was observed between thrombus age and SWE-derived kPa values (average: r = 0.770, median: r = 0.727, maximum: r = 0.835). Receiver operating characteristic (ROC) analysis demonstrated SWE’s high accuracy in differentiating thrombus age, with an optimal average cut-off value of 31.7 kPa, resulting in a sensitivity of 90.5% and specificity of 73.9%.
Conclusion: Shear wave elastography shows promise as a non-invasive tool for differentiating between acute and subacute thrombi in thrombosed AVFs, aiding in personalized treatment planning for dialysis patients.
Limitations: This study's patient numbers was not much.
Funding for this study: This study was not supported by any funding.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: All procedures performed in studies involving human participants were in accordance with the ethical standarts of the instituional and/or national research commitee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standarts.

Author Block: J. Csőre, A. Crichton, C. Karmonik, B. Benfor, T. L. Roy; Houston, TX/US
Purpose: Recent randomized trials have challenged the traditional endovascular-first approach for treating below-the-knee arterial disease. Scoring systems like TASC and GLASS overlook lesion composition and morphology, which influence peripheral vascular intervention (PVI) success. Conventional imaging provides limited plaque composition insight, while ultrashort echo time (UTE) MRI can distinguish between soft (e.g., fibrous tissue, thrombus) and hard (e.g., calcification, dense collagen) plaque components. This study aimed to assess if MRI-histology could better predict lesion crossing failure compared to GLASS and TASC scoring.
Methods or Background: Amputated limbs were collected from patients with chronic limb-threatening ischemia (CLTI) and scanned ex-vivo on a 3T MRI using UTE and T2w contrasts. Lesions were classified as 'hard' if >50% of the lumen was occluded by calcium or dense collagen based on the MRI. The distribution of hard components (eccentric, concentric, central), lumen stenosis caused by hard/soft components, and collagen density were recorded. Ex-vivo PVIs were carried out in a hybrid operating room and TASC and GLASS scoring was performed.
Results or Findings: Seventeen patients yielded 29 target lesions, 76% (22/29) of which were classified as ‘hard.’ Of these, 45% had a collagen-dominated composition. 'Hard' lesions showed a significantly higher crossing failure rate compared to 'soft' lesions (95% vs. 14%, p<.001). MRI scoring of 'hard' lesions was strongly associated with crossing success (p<.001), outperforming TASC and GLASS scoring (p=.062 and p=.112, respectively). Total vessel occlusion was not predictive of failure (p=0.64). Most crossing failures (64%) occurred in centrally distributed 'hard' lesions, though this was not significant.
Conclusion: This MRI-histology scoring system identifies plaque composition as a predictor of PVI failure, outperforming TASC and GLASS scoring, and highlighting MRI's potential role in preoperative assessment and device selection for CLTI patients.
Limitations: Single-center study, small cohort
Funding for this study: Jerold B. Katz Academy of Translational Science (project ID 15790002, recipient: Trisha Roy); American Heart Association Transformational Award (project ID: 17590004, recipient: Trisha Roy); National Institutes of Health Research Project grant (R01) (award ID: R01HL174587, recipient: Trisha Roy)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Institutional Review Board under study ID PRO00027258.

Author Block: T. Nemirovskaya, R. Bredikhin, R. Akhmetzyanov, E. Fomina, D. Ryabinina, A. Yaglova; Kazan/RU
Purpose: Pelvic venous diseases are considered widespread problem. Among etiological factors compression of left renal vein (LRV) between aorta and superior mesenteric artery (SMA), so-called nutcracker syndrome, is considered primary for symptoms evolvement. Diagnostic workflow includes selective phlebography, but CT-phlebography is gaining popularity. Primary issue is applicability of CT-phlebography results concerning surgical correction selection. Study objective was parameters assessment that could be accounted surrogate characteristics of pressure gradient in the left renal vein.
Methods or Background: Prospective assessment of CT-phlebography in patients with pelvic congestion syndrome was performed. Expiratory CT scanning was performed with 130 s delay after Iodinated contrast medium administration. Following measurements were performed: maximum diameter of pelvic veins, gonadal veins diameter, aorta/SMA angle. Three LRV areas were outlined orthogonally projected to gonadal tributary, aorta/SMA angle, inferior vena cava сonflux (IVC) with areas ratio calculation. LRV narrowing extension was also measured.
Results or Findings: 74 patients underwent IVC and tributaries delayed CT-angiography from 2022 to 2024. Mean age 37 years, 15 male, 59 female. All had pelvic veins enlargement with associated symptoms according to ultrasound examination and history. No severe development anomalies was observed except 3 cases of retroaortal LRV. Twelve cases were accompanied with May-Turner variant. Lineal regression assessment displayed correlation between aorta/SMA angle and maximum/minimum LRV areas ratio with p < 0.001, also with LRV narrowing extension (p = 0.003). May-Turner variant was contributing factor with more severe pelvic veins enlargement (p < 0.001). Correlation was found with pressure gradient according to direct phlebography, however only 19 patients underwent it.
Conclusion: CT-phlebography may be considered as supportive diagnostic modality to direct phlebography for selection candidates for surgical correction of pelvic congestion syndrome with LRV compression.
Limitations: Retrospective direct phlebography data collection with incomplete cohort coverage.
Funding for this study: No funding
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Institutional ethics board of Interregional Clinical Diagnostic Center

Author Block: B. Shou¹, J. Li², Y. Zou², W. Zhang¹, G. Zhang², X. Hu¹, F. Jiang¹, H. Hu¹; ¹Hangzhou, Zhejiang/CN, ²Shanghai/CN
Purpose: To assess the image quality and diagnostic value of artificial intelligence iterative reconstruction (AIIR) in low-dose upper extremity CT angiography for hemodialysis arteriovenous fistula or graft (AVF/G).
Methods or Background: A total of 56 patients with suspected or known AVF/G dysfunction were prospectively enrolled and were randomly divided into two groups: routine-dose group (RD-group, n=28) and low-dose group (LD-group, n=28). RD-group employed a routine CTA protocol (tube voltage: 100kVp; contrast dosage: 1.0ml/kg) with hybrid iterative reconstruction, while LD-group used the low-dose protocol (tube voltage: 80kVp; contrast dosage: 0.6ml/kg) with AIIR. Two radiologists independently scored the overall image quality using a 4-point scale (1=poor; 4=excellent). Area under the curve (AUC), accuracy, sensitivity, and specificity of two groups for detecting significant (>50%) stenosis were calculated on a pre-segment basis, using digital subtraction angiography (DSA) as the reference standard. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in fistula were also analyzed.
Results or Findings: No significant differences in demographics characteristic were observed between the two groups (all p>0.05). The radiation dose and contrast dosage in LD-group were reduced by 53% (224.56mGyxcm vs. 479.24mGyxcm) and 42% (36mL vs. 63mL), respectively, compared to the RD-group. The mean subjective scores between the RD-group and LD-group showed no significant difference (3.86±0.36 vs. 3.68±0.48, p=0.12). The AUC, accuracy, sensitivity, and specificity were 0.91, 90% (47/52 segments), 92%, and 99% for RD-group and were 0.94, 90% (47/52 segments), 100%, and 98% on a pre-segment basis for LD-group. In fistula, SNR and CNR of LD-group were 130% and 140% higher than those of RD-group, respectively (both p<0.001).
Conclusion: Low-dose CTA with AIIR provides superior image quality and maintains high accuracy for detecting stenosis in AVF/G, while significantly reducing radiation dose and contrast dosage.
Limitations: N/A
Funding for this study: N/A
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the local ethics Committee at the University Hospital.