We evaluated the long-term morphologic and clinical outcomes after thoracic endovascular aortic repair combined with parallel grafts (PG-TEVAR) for arch-involving aortic pathologies.
We performed a ...retrospective analysis of perioperative and follow-up data of patients who had undergone PG-TEVAR at a single vascular surgery center from November 2010 to April 2018. Patients with prior or simultaneous open chest or cervical debranching procedures or arch repair were excluded. The primary endpoint was freedom from overall PG-TEVAR–related reintervention. The secondary endpoints were parallel graft sealing zone failure (presence of gutter-related type I or Ic endoleak), PG failure (occlusion or reintervention), stroke, and 30-day and overall PG-TEVAR–related and all-cause mortality. Kaplan-Meier curves were used to estimate the freedom from reintervention and survival. Receiver operating characteristics curves were used to find the optimal cutoff to prevent type Ia endoleak-related reintervention.
A total of 33 patients, including 8 women, with a median age of 74 years (interquartile range, 67-79 years) had undergone PG-TEVAR (chimney, periscope, and sandwich in 20, 15, and 13 patients, respectively) with proximal landing in Ishimaru zone 0, 1, or 2 in 4, 5, and 24 patients, respectively. The aortic pathologies included type B aortic dissection (acute and chronic, eight and six, respectively), degenerative aneurysm (n = 10), type Ia endoleak (n = 3), para-anastomotic/patch aneurysm (n = 4), left subclavian artery aneurysm (n = 1), and traumatic rupture (n = 1). The perioperative stroke rate and 30-day mortality was 6% and 9%, respectively. Direct postoperative computed tomography revealed 28 endoleaks (gutter-related type Ia, 12; gutter-related type Ib, 9; type Ia, 2; type Ic, 2; type III, 1; undetermined, 2) in 27 patients. The technical and clinical success rate was 37% and 30%, respectively. The mean follow-up for survival was 48 ± 31 months. The latest radiologic follow-up demonstrated 12 remaining and 1 new endoleak. The early and overall PG sealing zone failure and PG failure was 73% and 36% and 9% and 18%, respectively. The overall PG-TEVAR–related reintervention rate was 33% (n = 11). The estimated freedom from overall PG-TEVAR–related reintervention was 68% at 60 months. The main graft oversizing and length oversizing rates were not significantly associated statistically with the type Ia endoleak-related reintervention rate. The PG-TEVAR–related and all-cause mortality were 18% and 34%, respectively.
PG-TEVAR for total endovascular repair of arch-involving aortic pathologies resulted in a high rate of type I endoleaks and the need for long-term reintervention. Gutter-related endoleaks might be more frequent than reported and should not be underestimated because they can lead to sac enlargement and reintervention. Frequent radiologic surveillance is mandatory. Further studies comparing PG-TEVAR to other total endovascular alternatives are required to confirm these findings.
Purpose: To compare open versus endovascular left subclavian artery debranching for thoracic endovascular aortic repair of thoracic aortic pathologies.Methods: This is a retrospective study of ...patients receiving left subclavian artery debranching in our institution from October 2009 to January 2020. The primary outcome was freedom from aortic reintervention. Secondary outcomes were type I endoleaks, left subclavian artery (LSA) debranching failure, stroke, technical or clinical success, procedure-related reintervention, as well as 30-day or overall all-cause and aorta-related mortality.Results: Forty-eight patients received parallel graft-based (n = 24, ENDO; median age 75 years 70–80 years) or open (n = 24, OPEN; median age 71 years 59–75 years) debranching for type B aortic dissection (n = 25), degenerative aneurysm (n = 12), type IA endoleak (n = 6), suture-associated (n = 3) or ostial LSA aneurysm (n = 1), or penetrating aortic ulcer (n = 1). The median follow-up was 36 months (13–61 months). After 16 months, aortic reintervention-free survival in groups OPEN and ENDO was 91% (95% confidence interval CI: 79 to 100%) and 86% (73 to 100%) (p = 0.71), respectively. After 36 months, all-cause survival in groups OPEN and ENDO was 74% (95% CI: 55 to 99%) and 79% (95% CI: 64 to 97%) (p = 0.74), respectively; freedom from aorta-related mortality was 81% (95% CI: 62 to 100%) and 91% (95% CI: 80 to 100%) (p = 0.78), respectively. Group OPEN presented less type I endoleaks (OPEN/ENDO = 3/19, p <0.001) and higher technical (OPEN/ENDO = 81/36%, p = 0.003) and clinical success rates (OPEN/ENDO = 67/36%, p = 0.047). No statistical differences were found for other outcomes.Conclusion: Both strategies achieved comparable reintervention and mortality rates, but open debranching should be preferred due to its higher technical and clinical success and less type I endoleaks.
Pulmonary embolism (PE) is a common disease with an annual incidence of about 1/1000 persons. About every sixth patient dies within the first 30 days after diagnosis. The electrocardiogram (ECG) is ...one of the first diagnostic tests performed, and is able to confirm the suspicion of PE with typical electrocardiographic signs. Some ECG signs and their regression are also prognostically relevant. Endovascular mechanical thrombectomy is one option for PE treatment, and aims to relieve right heart strain immediately. The first studies on endovascular mechanical thrombectomy using a dedicated device (FlowTriever System, Inari Medical, Irvine, CA, USA) yielded promising results.
In the following, we report the case of a 66-year-old male patient who presented with New York Heart Association III dyspnea in our emergency department. Among typical clinical and laboratory results, he displayed very impressive electrocardiographic and radiological findings at the time of PE diagnosis.
After endovascular mechanical thrombectomy, the patient's complaints and pulmonary hemodynamics improved remarkably. In contrast, the ECG worsened paradoxically 18 h after intervention. Nevertheless, control echocardiography 4 days after the intervention no longer showed any signs of right heart strain, and dyspnea had disappeared completely. At a 4-month follow-up visit, the patient presented as completely symptom-free with a high quality of life. His ECG and echocardiography were normal and excluded recurrent right heart strain.
Overall, the patient benefitted remarkably from endovascular mechanical thrombectomy, resulting in an almost complete resolution of electrocardiographic PE signs at the 4-month follow-up after exhibiting multiple typical electrocardiographic PE signs at time of diagnosis and initial electrocardiographic worsening 18 h post successful intervention.
To investigate the potential of texture analysis and machine learning to predict treatment response to transarterial radioembolization (TARE) on pre-interventional cone-beam computed tomography ...(CBCT) images in patients with liver metastases.
In this IRB-approved retrospective single-center study 36 patients with a total of 104 liver metastases (56 % male, mean age 61.1 ± 13 years) underwent CBCT prior to TARE and follow-up imaging 6 months after therapy. Treatment response was evaluated according to RECIST version 1.1 and dichotomized into disease control (partial response/stable disease) versus disease progression (progressive disease). After target lesion segmentation, 104 radiomics features corresponding to seven different feature classes were extracted with the pyRadiomics package. After dimension reduction machine learning classifications were performed on a custom artificial neural network (ANN). Ten-fold cross validation on a previously unseen test data set was performed.
The average administered cumulative activity from TARE was 1.6 Gbq (± 0.5 Gbq). At a mean follow-up of 5.9 ± 0.8 months disease control was achieved in 82 % of metastases. After dimension reduction, 15 of 104 (15 %) texture analysis features remained for further analysis. On a previously unseen set of liver metastases the Multilayer Perceptron ANN yielded a sensitivity of 94.2 %, specificity of 67.7 % and an area-under-the receiver operating characteristics curve of 0.85.
Our study indicates that texture analysis-based machine learning may has potential to predict treatment response to TARE using pre-treatment CBCT images of patients with liver metastases with high accuracy.
To investigate, by quantitative and qualitative enhancement measurements, the correlation between tumor enhancement on cone beam computed tomography (CBCT) images and treatment response at 6 months ...in patients undergoing transarterial radioembolization (TARE) for liver metastases.
36 patients (56% male; median age 62.5 years) with 104 metastases were retrospectively included. Quantitative and qualitative enhancement of liver metastases were evaluated on CBCT images before TARE. Quantitative analysis consisted of lesion enhancement measurements (ROI HU lesion – ROI HU relative to inferior vena cava). Qualitative analysis consisted of subjective enhancement pattern analysis (diffuse, sparse, rim-like or non-enhancing). Morphologic tumor response was evaluated according to RECIST 1.1 criteria on follow-up CT or MR imaging.
At a mean follow up of 6.5 ± 3.7 months, progressive disease (PD) was found in 4 patients, partial response (PR) in 11 and stable disease (SD) in 21. Relative lesion enhancement was significantly different between these groups (-37.5±154.2 HU vs. 103.8±93.4 vs. 181±144 HU in PD vs. SD vs. PR group, respectively; p<0.01). ROC analysis of relative lesion enhancement to predict progressive disease showed an area under the curve of 0.86 (p<0.01). For qualitative lesion enhancement analysis, no difference between groups was found.
Quantitative enhancement measurements derived from intraprocedural contrast enhanced CBCT may identify responders to TARE in patients with liver metastases.
OBJECTIVESThe aim of this study was to evaluate the ability of fusion of pretreatment magnetic resonance (MR) imaging with posttreatment perfusion–CT (P-CT) after radiofrequency ablation (RFA) of ...hepatocellular carcinomas (HCCs) and to determine treatment success in an objective, quantitative way.
MATERIALS AND METHODSIn this institutional review board–approved study, 39 patients (78.4% male; mean age 68.2 ± 8.5 years) with a total of 43 HCCs, who underwent RFA at our institution and had diagnostic pre-RFA MR imaging and post-RFA P-CT, were included in the study. Post-RFA P-CT was performed within 24 hours after RFA. In a first step, the pre-RFA MR imaging, depicting the HCC, was registered onto the post-RFA P-CT using nonrigid image registration. After image registration, the MR data were reloaded jointly with the calculated perfusion parameter volumes into the perfusion application for quantitative analysis. A 3-dimensional volume of interest was drawn around the HCC and the ablation zone; both outlines were automatically projected onto all perfusion maps. Resulting perfusion values (normalized peak enhancement NPE, %; arterial liver perfusion ALP, in mL/min/100 mL; BF blood flow, mL/100 mL/min; and blood volume BV, mL/100 mL) and histogram data were recorded. Local tumor recurrence was defined in follow-up imaging according to the EASL guidelines.
RESULTSImage registration of MR imaging and CT data was successful in 37 patients (94.9%). Local tumor recurrence was observed in 5 HCCs (12%). In the local tumor recurrence group (LTR-group), HCC size was significantly larger (22.7 ± 3.9 cm vs 17.8 ± 5.3 cm, P = 0.035) and the ablation zone was significantly smaller (29.8 ± 6.9 cm vs 39.3 ± 6.8 cm, P = 0.014) compared with the no-local tumor recurrence group (no-LTR group). The differences (ablation zone − tumor) of the perfusion parameters NPE, ALP, BF, and BV significantly differed between the 2 groups (all Pʼs < 0.005). Especially, the difference (ablation zone − tumor) of NPE and ALP, with a cutoff value of zero, accurately differentiated between LTR or no-LTR in all cases. A negative difference of these perfusion parameters identified local tumor recurrence in all cases.
CONCLUSIONSImage registration of pre-RFA MR imaging onto post-RFA P-CT is feasible and allows to predict local tumor recurrence within 24 hours after RFA in an objective, quantitative manner and with excellent accuracy.
Purpose: To compare open versus endovascular left subclavian artery debranching for thoracic endovascular aortic repair of thoracic aortic pathologies.Methods: This is a retrospective study of ...patients receiving left subclavian artery debranching in our institution from October 2009 to January 2020. The primary outcome was freedom from aortic reintervention. Secondary outcomes were type I endoleaks, left subclavian artery (LSA) debranching failure, stroke, technical or clinical success, procedure-related reintervention, as well as 30-day or overall all-cause and aorta-related mortality.Results: Forty-eight patients received parallel graft-based (n = 24, ENDO; median age 75 years 70–80 years) or open (n = 24, OPEN; median age 71 years 59–75 years) debranching for type B aortic dissection (n = 25), degenerative aneurysm (n = 12), type IA endoleak (n = 6), suture-associated (n = 3) or ostial LSA aneurysm (n = 1), or penetrating aortic ulcer (n = 1). The median follow-up was 36 months (13–61 months). After 16 months, aortic reintervention-free survival in groups OPEN and ENDO was 91% (95% confidence interval CI: 79 to 100%) and 86% (73 to 100%) (p = 0.71), respectively. After 36 months, all-cause survival in groups OPEN and ENDO was 74% (95% CI: 55 to 99%) and 79% (95% CI: 64 to 97%) (p = 0.74), respectively; freedom from aorta-related mortality was 81% (95% CI: 62 to 100%) and 91% (95% CI: 80 to 100%) (p = 0.78), respectively. Group OPEN presented less type I endoleaks (OPEN/ENDO = 3/19, p <0.001) and higher technical (OPEN/ENDO = 81/36%, p = 0.003) and clinical success rates (OPEN/ENDO = 67/36%, p = 0.047). No statistical differences were found for other outcomes.Conclusion: Both strategies achieved comparable reintervention and mortality rates, but open debranching should be preferred due to its higher technical and clinical success and less type I endoleaks.
•The flower-shaped pulsating heat pipe design can handle higher heat fluxes compared to the state-of-the-art design•The thermal resistance decreases due to continuous phase change processes in the ...evaporation chamber•The fluid oscillation is driven by the phase change in the evaporation chamber•Convective heat transfer is negligible in horizontal position
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Pulsating heat pipes (PHPs) are increasingly used for the thermal management of hot spots. A major goal in the design process of PHPs is the handling of high heat fluxes and, thus, improved thermal resistance. The thermal resistance can be reduced by increasing the latent or convective heat transfer. Two design approaches with that goal are presented in this study: a flower-shaped PHP design to increase the latent heat transfer and a star-shaped PHP design to increase the convective heat transfer. We compare the proposed designs to a state-of-the-art, meander-shaped PHP design. Thereby, we quantify the thermal performance and the flow pattern of the different PHP designs. The copper PHPs were filled with acetone and tested horizontally and vertically. The filling ratios varied from 0 % to 90 % and the heat inputs increased from 50 W to 200 W. Our results illustrate that the flower-shaped PHP design reduces the thermal resistance by 7 % in horizontal and 12 % in vertical position. We found a strong interrelation between flow pattern and heat transfer in PHPs. Our study shows that phase change plays a key role for the thermal resistance. Based on that, we provide design criteria to optimize the thermal capabilities of PHPs with a special focus on hot spots.
Abstract Luminescent coupling (LC) is a key phenomenon in monolithic tandem solar cells. This study presents a nondestructive technique to quantitatively evaluate the LC effect, addressing a gap in ...the existing predictions made by optical modeling. The method involves measuring the ratio of photons emitted from the high bandgap top cell that escape through the rear, contributing additional current to the bottom cell, and to those escaping from the front side of top cell. The findings indicate that in the analyzed monolithic perovskite/silicon tandem solar cells, more than 85% of the emitted photons escaping from the perovskite top cell are used to generate additional current in the bottom cell. This process notably reduces the mismatch in the generated current between each subcell, particularly when the current is limited by the low bandgap subcell. The presented method is applicable to a variety of monolithic tandem structures, providing vital information for subcell characterization, providing vital information for predicting energy output and optimization for outdoor applications.
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