RPS 1915 - Carotid and intracranial artery imaging

Author Block: J. P. Janssen¹, K. Kaya¹, R. A. Terzis¹, J. Tristram¹, R. J. Gertz¹, L. Goertz¹, L. Pennig¹, C. H. Gietzen¹, K. Weiss²; ¹Cologne/DE, ²Hamburg/DE
Purpose: To evaluate the acceleration of a 3D isotropic flow-independent non-contrast MRA (REACT) of the neck using Compressed SENSE (CS) combined with deep learning-based reconstruction (CS-AI).
Methods or Background: Thirty-four volunteers received cervical REACT at 3T ((acquired threefold: (1) CS factor 7 (scan time: 1:20 min), (2) CS factor 10 (0:55 min), and (3) CS-AI factor 10 (0:55 min)). Two radiologists rated the image quality of seven arterial segments and overall image noise. Additionally, a pairwise forced-choice comparison was conducted. Apparent signal- (aSNR) and contrast-to-noise ratios (aCNR) were measured, and image sharpness was assessed by calculating the edge rise distance (ERD). Multiple t-tests and non-parametric tests with Bonferroni correction were performed for comparison to CS7, which was considered as the current clinical standard.
Results or Findings: Compared to CS7, CS10 showed lower image quality scores (p<0.001) while CS10-AI obtained higher results (p=0.010). Image noise was similar between CS7 and CS10 (p=0.138) while CS10-AI yielded a lower noise (p=0.008). Forced choice revealed preferences for CS7 over CS10 (p<0.001), but no preference between CS7 and CS10-AI (p>0.999). Compared to CS7, aSNR and aCNR were lower in CS10 (p<0.001) and the ERD was longer (p=0.004), while CS10-AI provided better aSNR and aCNR (p=0.001) and showed no difference in ERD (p=0.776).
Conclusion: CS-AI enables the acquisition of cervical REACT in less than one minute without compromising image quality. Further studies are required to confirm these results in patients and to evaluate the diagnostic performance regarding vascular findings such as stenosis or dissection.
Limitations: No pathologies were assessed. No comparison was made with established reference standards.
Funding for this study: Not applicable.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Approved by our institutional review board (reference number: 20-1296_1) and registered in the national registry for clinical trials (DRKS00030210).

Author Block: A-I. Nica¹, C. Booz¹, G. M. Bucolo¹, L. S. Alizadeh¹, T. Vogl¹, T. D'Angelo², H-L. Kaatsch³, D. Overhoff³, S. Waldeck³; ¹Frankfurt/DE, ²Messina/IT, ³Koblenz/DE
Purpose: The purpose of this study is to evaluate the impact of low-energy VMI reconstructions on quantitative and qualitative image quality, vascular contrast, and diagnostic assessability of the carotid arteries in photon-counting CTA.
Methods or Background: A total of 122 patients (67 male) who had undergone dual-source photon-counting CTA scans of the carotid artery were retrospectively analyzed in this study. Standard 120 kV CT images and low-keV VMI series from 40 to 100 keV with an interval of 15 keV were reconstructed. Quantitative analyses included the evaluation of vascular CT numbers, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). CT number measurements were performed in the common, external, and internal carotid arteries. Qualitative analyses were performed by three board-certified radiologists independently using five-point scales to evaluate image quality, vascular contrast, and diagnostic assessability of the carotid arteries.
Results or Findings: Mean attenuation, CNR and SNR values were highest in 40 keV VMI reconstructions (HU, 1362.32 ± 457.81; CNR, 33.19 ± 12.86; SNR, 34.37 ± 12.89) followed by 55-keV VMI reconstructions; all three mean values at these keV levels were significantly higher compared with standard 120 kV CT series (HU, 154.43 ± 23.69; CNR, 16.34 ± 5.47; SNR, 24.44 ± 7.14) (p < 0.0001). The qualitative analysis showed highest rating scores for 55 keV VMI reconstructions followed by 40 keV and 70 keV VMI series with a significant difference compared to standard 120 kV CT images regarding image quality, vascular contrast, and diagnostic assessability of the carotid arteries (all comparisons, p < 0.01).
Conclusion: Low-keV VMI reconstructions at a level of 40–55 keV significantly improve image quality, vascular contrast, and the diagnostic assessability of the carotid arteries compared with standard CT series in photon-counting CTA.
Limitations: Single-center retrospective study
Funding for this study: No funding was received
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The local IRB approved this study.

Author Block: K. Gasbarrino¹, A. Benjamin¹, T. Beiko¹, J. Ramirez-Garcia Luna¹, R. Khan¹, L. H. Gonzalez Torres¹, S. Levasseur¹, S. Taj², K. Khan¹; ¹Montreal/CA, ²Columbia, MD/US
Purpose: The standard approach to assessing stroke risk via 2D carotid ultrasound is limited by operator variability, a lack of 3D vessel visualization, and subjective interpretation, resulting in a nearly 30% misclassification rate. To address these challenges, we developed AI-powered software that transforms 2D ultrasound images into precise 3D models of carotid arteries and automates vessel measurements.
Methods or Background: We applied a multi-class U-Net AI model, trained on ~4000 2D ultrasound images from 113 North American patients with cardiovascular risk factors. Two independent sonographers annotated these images, identifying key vascular structures, including medial-adventitial boundary, intimal-luminal boundary, and plaque. 3D reconstructions were achieved by integrating 2D image segmentations with positional data captured from an electromagnetic sensor (Northern Digital Inc, Canada) during a single B-mode sweep of the carotid artery. Algorithms were developed for automated measurement of vessel diameter, artery stenosis, and classification of disease severity. Validation was conducted using a carotid artery phantom with a predefined 70% stenosis (R.G. Shelley Ltd, Canada), along with clinical evaluation in 8 patients to compare performance against the current standard of care.
Results or Findings: The AI model demonstrated strong performance, achieving a DICE coefficient of 0.86 in detecting vessel structures. The software successfully generated 3D models, with vascular metrics showing a 99% agreement with the known stenosis in the phantom model. Intra-operator variability was minimal, with stenosis measurements showing only minor deviations (71.42±3.42%). In the clinical study, a 90% reduction in ultrasound scan was achieved, while maintaining diagnostic accuracy equivalent to that of a vascular radiologist with >10 years of experience.
Conclusion: Our software represents a significant advancement in carotid artery imaging, delivering a ten-fold improvement in scan efficiency while achieving expert-level diagnostic accuracy with minimal variability.
Limitations: N/A
Funding for this study: Ontario Brain Institute; Québec's Ministère de l'Économie, de l'Innovation et de l'Énergie
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study was approved by Advarra IRB (Pro00068778)

Author Block: Z. Cui, J. Zhang; Shanghai/CN
Purpose: This study aimed to investigate the association between pericarotid fat density (PFD) around the occlusion and hemorrhagic transformation (HT) risk and functional outcome in acute ischemic stroke (AIS) patients with extracranial internal carotid artery (e-ICA) occlusion who underwent endovascular thrombectomy (EVT).
Methods or Background: This multicenter retrospective study included a cohort of patients with e-ICA occlusion after EVT between June 2019 and March 2024. PFD was assessed using semi-automated quantitative software at pre-operation neck CT angiography (CTA). The associations between PFD and HT, and functional outcome (mRS score 0-3 vs 4-6) were analyzed using multivariable logistic regression. A mediation analysis was conducted to explore whether HT mediates the relationship between PFD and functional outcome. Additionally, We sought the association between PFD and admission C-reactive protein (CRP) levels.
Results or Findings: 101 patients were included and divided into an HT group (n=36) and a non-HT group (n=65). PFD was independently associated with HT (adjusted odds ratio [aOR]: 1.84, 95% CI: 1.28 to 2.66, P<0.001) and unfavorable functional outcome (1.41, 1.04 to 1.91, p=0.030). The AUC values were 0.79 (95% CI, 0.70 to 0.89) and 0.68 (0.57 to 0.78), indicating a favorable predictive performance for the HT risk and unfavorable prognosis prediction. Mediation analysis revealed that HT explained more than 60% of the relationship between PFD and worse functional outcome. In addition, higher PFD was positively correlated with elevated CRP levels.
Conclusion: PFD is an independent predictor of HT and a worse functional outcome at 90 days in patients with AIS and e-ICA occlusion who underwent EVT. Evaluation of PFD provides opportunities for HT risk stratification and outcome prediction.
Limitations: Given the sample size, we were unable to apply the more stringent inclusion criteria of restricted to the extracranial ICA.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: Informed consent was waived for all participants due to the retrospective nature of the study.

Author Block: M. Beraia, D. Gachechiladze, A. Siradze, N. Eliava, M. Lazarashvili, N. Nikabadze, S. Siradze, J. Giorgelashvili, L. Udumashvili; Tbilisi/GE
Purpose: The retina offers a unique window into brain structure and functional disorders due to its anatomical, physiological, and embryological similarities with the brain. This research explores the influence of visual-verbal/nonverbal stimuli on blood flow in both the retina and brain.
Methods or Background: A duplex Ultrasound study was conducted with 25 volunteers (11 males, 14 females, aged 21–35), examining blood flow in the central retinal artery (CRA) and internal carotid artery (ICA) under two types of visual stimuli: verbal irritation (Shakespeare’s sonnets) and nonverbal (pictures – find the hidden figures). Blood flow parameters (Vsys, Vdia, PI, and RI) were measured in intervals 1-15 and 25-40 seconds after stimuli initiation, to assess the nature (neuro/humoral) of blood flow regulation (RBC circulation time: 20 seconds). Initial 5sec for the baseline images. CE-MRI angiography (TOF) was used to exclude vascular anomalies.
Results or Findings: In the CRA, Vsys increased from 7.5–11.5 cm/sec to 10.7–14.3 cm/sec, with Vdia at 4.1–4.9 cm/sec. RI rose from 0.53 to 0.64, and PI from 0.71 to 0.94.
In the ICA, Vsys rose from 80–130 cm/sec to 95–170 cm/sec, with Vdia at 24–45 cm/sec. RI increased from 0.67 to 0.74, and PI from 1.01 to 1.17.
Changes in the CRA and ICA were unidirectional (r = 0.7). In nonverbal cases, Vsys and RI were higher in the CRA (P < 0.05) and ICA (P < 0.01). The time of the stimuli initiation did not change the results. These details indicate the mostly sympathetic regulation of cerebral blood flow.
Conclusion: Quantitative blood circulation studies in these arteries may be used as the functional ultrasound diagnostics of the retina and brain.
Limitations: Not applicable.
Funding for this study: No funding was provided for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The ethics committee notification can be found under the
number UID 2438.

Author Block: J. Van Der Bie¹, B. P. Berghout¹, R. P. J. Budde¹, J. Gutierrez², M. Van Straten¹, D. Bos¹; ¹Rotterdam/NL, ²New york, NY/US
Purpose: To assess the performance of photon-counting detector CT (PCD-CT) in detecting and quantifying intracranial arterial calcifications and comparing the performance to conventional energy-integrating CT (EID-CT), using micro-CT (µCT) as the reference standard.
Methods or Background: Thirty histopathological cross-sections of intracranial arteries were scanned with PCD-CT, EID-CT, and µCT. µCT was optimized for image quality (reference standard), while clinical protocols were used for PCD-CT and EID-CT. Various reconstruction kernels (EID-CT: Hv40/Hv49/Hv59; PCD-CT: Hv40/Hv48/Hv56/Hv64/Hv72/Hv89) were used to enhance spatial resolution. Two experienced observers independently evaluated the presence of calcifications in all acquisitions and were compared by Cohen’s Kappa and concordance percentages. For objective analysis, mass scores were used to assess both the detection and mass. The objective measure was analyzed using Bland-Altman plots.
Results or Findings: Observer 1 detected calcifications in 24 samples and Observer 2 in 23 samples using µCT (90% concordance, κ=0.706). EID-CT with Hv59 showed the highest interobserver agreement (97% concordance, κ=0.911), but low detection rates (observer 1: 27%, observer 2: 25%) compared to µCT. PCD-CT yielded better detection with Hv48 (observer 1: 70% detection rate, 90% concordance, κ=0.706) and Hv56 (observer 2: 80% detection rate, 77% concordance, κ=0.314). Mass scores indicated the highest detection with PCD-CT Hv64, though with increased noise. The Hv48/Hv56 kernels were deemed optimal, yielding sensitivity, and specificity (for observers 1/2) of 83%/92%, 50%/83%, respectively, and accuracy of 77%/90%.
Conclusion: PCD-CT outperformed EID-CT in detecting intracranial calcifications. Nevertheless, small calcifications sometimes go undetected compared to µCT. Hv48 and Hv56 kernels are recommended for optimal results, balancing detection rates and noise.
Limitations: In the observer study, detection was assessed on a sample basis, leading to potential oversight of smaller calcifications in segments where larger ones were present, which is reflected in the mass scores.
Funding for this study: This study has received funding by Smart*Light is partially funded by the Interreg V Flanders-Netherlands program with financial support from the European Regional Development Fund (ERDF).
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: All brain sources were approved by the IRB at their respective institutions. The Institutional Review Board waived written informed consent:

Author Block: Y. Wang¹, F. Zhou²; ¹Nanchang/CN, ²NanChang City, Jiangxi Province, China/CN
Purpose: Neuroimaging studies have indicated that altered cerebral blood flow (CBF) was associated with the long-term symptoms of long COVID. long COVID were found to be strongly associated with host gene expression. Nevertheless, the relationships between altered CBF, clinical symptoms, and gene expression in the central nervous system (CNS) remain unclear in individuals with long COVID
Methods or Background: First, CBF pattern was computed from arterial spin labeling sequence in long COVID. Next, using CNS gene expression data from the AHBA transcriptomic dataset, we conducted the spatial correlation between CBF and gene expression to defined the CBF-related genes. Functional enrichment analyses were applied to understand the biological functions of CBF-related genes. The cell type-specific expression analyses is utilized to identify the CNS cell types most closely associated with long COVID-19
Results or Findings: Lower CBF in left frontal-temporal gyrus was associated with higher fatigue and worse cognition in long COVID. This CBF pattern was spatially associated with the expression of 2,178 genes, which significantly overlap with the genes reported to interact with SARS CoV-2 proteins (odds ratio= 1.60, P= 0.0036). Functional enrichment analyses indicated these 2,178 genes were enriched in the molecular functions and biological pathways of COVID-19. Additionally, these genes were strongly associated with the oligodendrocyte progenitor cells, astrocytes, and myelinating oligodendrocytes of the cortex. ALL above results were corrected for multiple comparisons
Conclusion: Lower CBF is associated with persistent clinical symptoms in long COVID individuals, possibly as a consequence of the complex interactions among multiple COVID-19-related genes, which contributes to our understanding of the impact of adverse CNS outcomes and the trajectory of development to long COVID.
Limitations: The heterogeneity of clinical symptoms at the time of scanning may affect gene expression in individuals with long COVID.
Funding for this study: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this
article: This work was supported by the COVID-19 Research Project of the leading medical discipline in Jiangxi Province,
Jiangxi Province Double Thousand Talent Plan (jxsq2023201039), Clinical Research Center for Medical Imaging In Jiangxi Province (20223BCG74001) and Jiangxi Province Key Laboratory for Precision Pathology and
Intelligent Diagnosis (2024SSY06281).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The present study was approved by the Ethics Committee of the First Affiliated Hospital of Nanchang University (IIT2023018)