Dual-Energy Computed Tomography as an Adjunct in the Evaluation of Peripheral Chronic Total Occlusions: A Feasibility Study.

This study investigated the role of dual-energy computed tomography (CT) for lesion characterization in patients with peripheral arterial disease manifesting with chronic total occlusions (CTOs). Forty-one symptomatic patients with CTOs underwent dual-energy CT angiography before endovascular treatment. The lesions were subsequently analyzed in a dedicated workstation, and 2 indexes-dual-energy index (DEI) and effective Z (Zeff)-were calculated, ranging from 0.0027 to 0.321 and from 6.89 to 13.02, respectively. Statistical analysis showed a significant correlation between the DEI and Zeff values (P < .001). The interobserver intraclass correlation coefficient was 0.91 for the mean Zeff values and 0.86 for the mean DEI values. This technique could potentially provide useful information regarding the composition of a CTO.

Radiomics and Machine Learning Can Differentiate Transient Osteoporosis from Avascular Necrosis of the Hip.

Differentiation between transient osteoporosis (TOH) and avascular necrosis (AVN) of the hip is a longstanding challenge in musculoskeletal radiology. The purpose of this study was to utilize MRI-based radiomics and machine learning (ML) for accurate differentiation between the two entities. A total of 109 hips with TOH and 104 hips with AVN were retrospectively included. Femoral heads and necks with segmented radiomics features were extracted. Three ML classifiers (XGboost, CatBoost and SVM) using 38 relevant radiomics features were trained on 70% and validated on 30% of the dataset. ML performance was compared to two musculoskeletal radiologists, a general radiologist and two radiology residents. XGboost achieved the best performance with an area under the curve (AUC) of 93.7% (95% CI from 87.7 to 99.8%) among ML models. MSK radiologists achieved an AUC of 90.6% (95% CI from 86.7% to 94.5%) and 88.3% (95% CI from 84% to 92.7%), respectively, similar to residents. The general radiologist achieved an AUC of 84.5% (95% CI from 80% to 89%), significantly lower than of XGboost (p = 0.017). In conclusion, radiomics-based ML achieved a performance similar to MSK radiologists and significantly higher compared to general radiologists in differentiating between TOH and AVN.

Evaluation of foot hypoperfusion and estimation of percutaneous transluminal angioplasty outcome in patients with critical limb ischemia using intravoxel incoherent motion microperfusion MRI.

OBJECTIVES: To emerge hypoperfusion of lower limbs in patients with critical limb ischemia (CLI) using Intravoxel Incoherent Motion microperfusion magnetic resonance imaging (IVIM-MRI). Moreover to examine the ability of IVIM-MRI to differentiate patients with severe peripheral arterial disease (PAD) from normal subjects and evaluate the percutaneous transluminal angioplasty (PTA) results in patients with CLI. METHODS: Eight patients who presented with CLI and six healthy volunteers were examined. The patients underwent IVIM-MRI of lower extremity before and following PTA. The imaging protocol included sagittal diffusion-weighted (DW) sequences. DW images were analyzed and color parametric maps of the micro-circulation of blood inside the capillary network (D*) were constructed. The studies were evaluated by two observers to define interobserver reproducibility. RESULTS: Technical success was achieved in all patients (8/8). The mean ankle-brachial index increased from 0.35 ± 0.2 to 0.76 ± 0.25 (p < 0.05). Successful revascularization improved IVIM microperfusion. Mean D* increased from 279.88 ± 13.47 10-5 mm2/s to 331.51 ± 31 10-5 mm2/s, following PTA, p < 0.05. Moreover, PAD patients presented lower D* values as compared to healthy individuals (279.88 ± 13.47 10-5 mm2/s vs 332.47 ± 22.95 10-5 mm2/s, p < 0.05, respectively). Good interobserver agreement was obtained with an ICC = 0.84 (95% CI 0.64-0.93). CONCLUSIONS: IVIM-MRI can detect differences in microperfusion between patients with PAD and healthy individuals. Moreover, significant restitution of IVIM microperfusion is found following successful PTA. ADVANCES IN KNOWLEDGE: IVIM-MRI is a safe, reproducible and effective modality for evaluation of lower limb hypoperfusion in patients with PAD. It seems also to be a helpful tool to detect changes of tissue perfusion in patients with CLI following revascularization.

Discrimination of High-Risk Type-2 Endoleak after Endovascular Aneurysm Repair through CT Perfusion: A Feasibility Study.

A type-2 endoleak after an endovascular aneurysm repair is the most prevalent type of endoleak, but as the clinical consequence of its diagnosis is uncertain, at present, management decisions are solely based on aneurysm sac growth. The aim of this study was to investigate the potential of various computed tomography perfusion parameters for their ability to distinguish high-risk type-2 endoleaks from low-risk type-2 endoleaks after an endovascular aneurysm repair.

Endovascular Treatment of Malignant Superior Vena Cava Syndrome through Upper-Limb Access: A Comparison between Venous-Dedicated and Conventional Stents.

PURPOSE: To retrospectively evaluate the technical and clinical outcomes of superior vena cava (SVC) stent placement through upper-limb venous access in malignant SVC syndrome (SVCS) and compare the efficacy of different nitinol stent types. MATERIALS AND METHODS: Between 2006 and 2018, 156 patients (132 male; mean age, 62 y; age range, 33-81 y) underwent SVC stent placement for malignant obstructions through upper-limb venous access with 1 of 3 types of nitinol stent: 1 venous-dedicated (Sinus-XL stent) and 2 non-venous-dedicated (E-Luminexx Vascular Stent and Protégé GPS). Cases of common femoral vein access or non-nitinol stents were excluded from further analysis. The mean duration of follow-up was 8 mo. RESULTS: Technical success was achieved in 99.3% of cases. One patient died during the procedure as a result of cardiac tamponade. Balloon predilation was performed in 10 patients and postdilation in 126. Mean procedural time was 34.4 min (range, 18-80 min). Overall survival rates were 92.3%, 57.3%, and 26.8%, and overall primary patency rates were 94.5%, 84.8% and 79.6%, at 1, 6, and 12 mo, respectively. There were no statistically significant differences in primary patency rates between venous- and non-venous-dedicated stents or among different Stanford SVCS grading groups (P > .05). CONCLUSIONS: SVC stent placement through an upper-limb approach is a safe, fast, and effective technique. There is no evident benefit of venous-dedicated vs non-venous-dedicated stents in the treatment of malignant SVCS.

Complexity-based local diagnostic reference levels (DRLs) for standard endovascular aneurysm repair (EVAR) procedures.

PURPOSE: The aim of this study was to establish complexity-based local diagnostic reference levels (DRLs) for standard endovascular aneurysm repair (EVAR) procedures. METHODS: Dosimetric data for 73 consecutive patients were collected prospectively. All procedures were performed on a Siemens Axiom Artis FA angiographic unit (Siemens, Erlangen, Germany). Fluoroscopy time (FT), dose area product (DAP), air kerma (Ka.r) at reference point as well as patient's age, height and weight were recorded for each procedure. Moreover, the complexity level of each procedure was evaluated. Spearman rank correlation tests were used to evaluate the degree of association between variables. RESULTS: 2nd quartiles of DAP for low, medium and high complexity standard EVAR procedures were 144.2 Gycm2, 160.1 Gycm2 and 189.5 Gycm2respectively. The median DAP of the full sample was 153.2 Gycm2. Statistical analysis showed a strong correlation between BMI and DAP (r = 0.68, p-value < 0.0001) and a moderate correlation between BMI and Ka.r (r = 0.52, p-value < 0.0001). Furthermore, a strong correlation was found between Ka.r and FT (r = 0.76, p-value < 0.0001) and a moderate correlation was found between DAP and FT (r = 0.57, p-value < 0.0001). CONCLUSION: The complexity of an EVAR procedure is associated with the total burden of radiation. Establishment of complexity-based DRLs for interventional radiology procedures can contribute to the radiation protection of patients and staff.

Dynamic CT perfusion imaging for type 2 endoleak assessment after endograft placement.

Endovascular repair of abdominal aortic aneurysm is a widely performed treatment method due to its minimal invasiveness, reduced need for intensive care unit (ICU), shorter hospitalization and lower 30-day morbidity and mortality compared to open surgery. Endoleak is the drawback of this procedure and is considered the main culprit for re-interventions due to the risk of late aneurysm sac growth and rupture. Type 2 endoleak (T2EL) is the most common type of endoleak which is also the most controversial regarding its management. The aim of this paper is to investigate the potential of dynamic contrast-enhanced CT for the assessment of T2EL after endovascular aneurysm repair using qualitative and quantitative image analysis of the aneurysmal sac.

CT Foot Perfusion Examination for Evaluation of Percutaneous Transluminal Angioplasty Outcome in Patients with Critical Limb Ischemia: A Feasibility Study.

PURPOSE: To evaluate foot perfusion in patients with critical limb ischemia (CLI) using quantitative perfusion multi-detector-row CT and estimate perfusion parameter changes before and after percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: This prospective study investigated 13 patients (10 men; median age, 72 y; range, 51-84 y) with CLI who underwent CT foot perfusion examinations with a 128-slice dual-energy CT scanner 1 day before and 1 week after PTA. Key parameters such as permeability surface (PS), blood volume (BV), and blood flow (BF) were analyzed and compared statistically. The studies were also examined by a second observer to determine interobserver reproducibility. RESULTS: Revascularization was technically successful in all patients, and mean ankle-brachial index increased from 0.36 ± 0.16 to 0.75 ± 0.22. After revascularization, mean BV increased from 1.55 mL/100 g ± 0.83 to 4.51 mL/100 g ± 1.53, BF increased from 16.28 mL/100 g/min ± 4.97 to 31.49 mL/100 g/min ± 6.86, and PS increased from 3.1 mL/min/100 g ± 1.95 to 8.67 mL/min/100 g ± 3.85 (P < .05). Patients with poor response to revascularization who finally underwent amputation presented lower post-PTA perfusion parameters values than patients with significant clinical improvement (P < .05). All measurements demonstrated very good interobserver reproducibility, and intraclass correlation coefficients were 0.91 for BV, 0.94 for BF, and 0.95 for PS. The mean effective dose of the examination was estimated at 0.29 mSv. CONCLUSIONS: CT foot perfusion is a reproducible technique that may be a useful modality for the estimation of PTA outcome. Significant restitution of perfusion parameters was observed after successful revascularization.

Transcatheter arterial chemoembolization combined with radiofrequency or microwave ablation for hepatocellular carcinoma: a review.

Hepatocellular carcinoma (HCC) is the sixth most common type of malignancy. Several therapies are available for HCC and are determined by stage of presentation, patient clinical status and liver function. Local-regional treatment options, including transcatheter arterial chemoembolization, radiofrequency ablation or microwave ablation, are safe and effective for HCC but are accompanied by limitations. The synergistic effects of combined transcatheter arterial chemoembolization and radiofrequency ablation/microwave ablation may overcome these limitations and improve the therapeutic outcome. The purpose of this article is to review the current literature on these combined therapies and examine their efficacy, safety and influence on the overall and recurrence-free survival in patients with HCC.