Early experience with bridging stent graft deployment without sheath support in branched and fenestrated endovascular aortic repair.

OBJECTIVE: To assess the early experience with modified version of simplified bare-wire target vessel (SMART) technique, implying delivery of bridging stent grafts without historically established sheath support, and to compare its outcome to standard endovascular aortic repair procedures with fenestrated/branched devices. METHODS: A retrospective analysis of 102 consecutive patients treated with fenestrated/branched devices from January 2020 to December 2022 was undertaken. The study population was divided into three groups-a sheath group (SG), SMART group, and nonsheath group (NSG). Primary end points were radiation exposure (dose-area product), fluoroscopy time, dose of contrast agent, operation time, and incidence of intraoperative target vessel (TV) complications and additional procedures. Freedom from secondary TV related reinterventions at the three follow-up phases were defined as secondary end points. RESULTS: A total of 183 TVs (38.8% visceral arteries [VA]; 56.3% renal arteries [RA]) in the SG, 36 TVs (44.4% VA, 55.6% RA) in the SMART group, and 168 TVs (47.6% VA; 50% RA) in the NSG were accessed. The mean number of fenestrations and bridging stent grafts was equally distributed in all three groups. The SMART group only included cases treated with fenestrated devices. The dose-area product was significantly lower in the SMART (median, 203 Gy × cm2; interquartile range [IQR], 179-365 Gy × cm2) and NSG (median, 340 Gy × cm2; IQR, 220-651 Gy × cm2) groups vs the SG (median, 464 Gy × cm2; IQR, 267-871 Gy × cm2; P = .007). Operation time was also significantly lower in the NSG (median, 265 minutes; IQR, 221-337 minutes) and SMART (median, 292 minutes; IQR, 234-351 minutes) groups vs the SG (median, 326 minutes; IQR, 277-375 minutes; P = .004), respectively. Intraoperative TV-related complications were most frequently observed in the SG (9/183 TVs; P = .008). CONCLUSIONS: This study reports the outcomes of three currently available TV stenting approaches. Previously reported SMART technique, and its modified version (NSG) proved to be a safe alternative to historically established TV stenting technique with sheath support (SG).

Monoplane versus biplane fluoroscopy in patients undergoing fenestrated/branched endovascular aortic repair.

OBJECTIVE: Endovascular aortic repair (EVAR) with fenestrated (F-EVAR) or branched (B-EVAR) endografts represents an indispensable tool of modern patient care in vascular surgery. The purpose of this retrospective study was to evaluate the center's initial experience of F/B-EVAR procedures performed under biplane angiography guidance compared with a historical control group. METHODS: From January 2020 to March 2022, 80 consecutive patients underwent F/B-EVAR under general anesthesia at a single institution. As from January 2021, the deployment of complex stent grafts was performed using an alternative intraoperative imaging modality-a biplane fluoroscopy and angiography. The cohort was divided into monoplane (MPA) and biplane (BPA) groups according to the imaging modality applied. The end points were operation time, fluoroscopy time, radiation exposure, dose of contrast agent, and technical success. RESULTS: The MPA group included 59 patients (78% male; median age; 74 years; interquartile range [IQR], 66-78 years) and the BPA group 21 patients (85.7% males; median age, 75 years; IQR, 69-79 years). Operation time (median, 320 minutes; IQR, 266-376 minutes) versus (median, 275 minutes; IQR, 216-333 minutes) was significantly lower in the BPA group (P = .006). The median fluoroscopy time (median, 82 minutes; IQR, 57-110 minutes vs median, 68 minutes; IQR, 54-92 minutes), contrast agent volume applied (median, 220 mL; IQR, 179-250 mL vs median, 200 mL; IQR, 170-250 mL), and radiation dose (dose-area product, median, 413 Gy × cm2; IQR, 249-736 Gy × cm2; vs median, 542 Gy × cm2; IQR, 196-789 Gy × cm2) were similar in both groups. Technical success of 96.6% (57/59 cases) versus 100% (21/21 cases) could be achieved in MPA and BPA group, respectively. CONCLUSIONS: F/B-EVAR procedures performed under BPA guidance were associated with a significant decrease in operation time.

Endovascular Repair of Penetrating Thoracic Aortic Ulcers Using Tubular Stent Grafts Versus Stent Grafts With a Proximal Scallop.

PURPOSE: In penetrating aortic ulcers (PAUs), limited data support tubular thoracic endovascular aortic repair (TEVAR) as a viable treatment option. For treatment of more proximal PAUs, hybrid approaches and-more recently-scalloped TEVAR (scTEVAR) have been advocated. Outcomes of scTEVAR specifically for PAUs have not yet been reported. This study reports long-term outcomes for tubular and scTEVAR in PAUs and compares the safety profile in both cohorts regarding the significantly more proximal landing zone (LZ) for scTEVAR. MATERIALS AND METHODS: This single-center retrospective cohort study includes all nonacute patients treated for complicated PAU with scTEVAR and tubular TEVAR. Patient and PAU characteristics as well as procedural success, complication and reintervention rates, and all-cause and aortic mortality were analyzed. RESULTS: Of 212 TEVAR procedures reviewed, 21 patients with tubular TEVAR and 19 patients with scTEVAR were included. Patient and PAU characteristics were similar, and LZ was significantly more proximal in the scTEVAR cohort (p=0.0001), with similar number and types of supra-aortic revascularization procedures. Clinical success was reached in all 40 patients (100%), and reintervention rate was 2/21 (9.5%) and 1/19 (5.3%), respectively. Over the mean follow-up of 63 (TEVAR) and 53 (scTEVAR) months, clinical success was stable in all patients with one (abdominal) aortic-related mortality in the scTEVAR cohort. CONCLUSION: Treatment of complicated PAUs with TEVAR as well as scTEVAR provides excellent and similar clinical success, stability of clinical success, and aortic survival with acceptable complication and reintervention rates. Scalloped TEVAR safely lengthens the proximal sealing zone to address more proximal pathologies. CLINICAL IMPACT: Treatment of asymptomatic complicated penetrating aortic ulcers (PAUs) with thoracic endovascular aortic repair (TEVAR) provides excellent clinical success and acceptable complication and reintervention rates. More patients become amenable to endovascular treatment by including scalloped TEVAR (scTEVAR) as a means to safely lengthen the proximal sealing zone to address more proximal pathologies.

Applicability of endovascular branched and fenestrated aortic arch repair devices to treat residual type A dissection after ascending replacement.

OBJECTIVE: Endovascular repair of post-type A aortic dissection (PTAD) after open ascending replacement has recently been shown as safe and feasible, but with limited anatomic applicability because only one stent graft was evaluated. We assessed anatomic and clinical applicability of six commercially available branched/fenestrated stent grafts for endovascular repair of PTAD. METHODS: On postoperative CT scans of 101 patients, we measured the aortic diameter at the sinutubular junction, supra-aortic vessels, and descending aorta, as well as the distances between these landmarks along the outer curvature of the arch and the diameters of the supra-aortic vessel. Anatomic applicability was evaluated according to the instructions for use, clinical applicability with regard to supra-aortic and iliac arteries. Assessed devices were the Cook aortic double branch, Terumo double branch, Najuta fenestrated, Endospan Nexus, Medtronic Mona LSA, and Gore TAG thoracic branch. RESULTS: Single devices were anatomically and clinically applicable between 19 of 101 (Mona LSA) and 83 of 101 (Najuta) cases. Reasons for rejection varied considerably across devices. With all devices available, anatomic applicability was 97 of 101 and clinical applicability 95 of 101. Combinations of a fenestrated and a branched device showed the most favorable clinical applicability for a pair of two devices, ranging from 86 of 101 to 94 of 101. CONCLUSIONS: Anatomic and clinical applicability of endovascular devices for the repair of PTAD is high for fenestrated and branched devices, and very high for the combination of fenestrated and branched devices. Manufacturers should amend specific device requirements for PTAD. Surgeons should emphasize the need for a sufficiently long and straight graft as a potential landing zone.

Novel prefabricated bovine pericardial grafts as alternate conduit for septic aortoiliac reconstruction.

OBJECTIVE: Infection of prosthetic aortic grafts represents a serious complication with high morbidity and mortality. Replacement with autologous material is recommended; however, in its absence, biological material should be favored. In the present retrospective cohort study, we evaluated the short- and midterm results with the use of commercially available prefabricated bovine pericardium grafts (BPGs) used for the management of aortic graft infection or aortic reconstructive surgery in the presence of systemic infection. METHODS: We performed a retrospective analysis of patients in whom BPGs had been used for aortic reconstruction at two vascular centers. Prefabricated vascular pericardium grafts were preferred over other biological reconstruction techniques for selected cases. Comorbidities, procedure-related details, perioperative morbidity, clinical outcomes, and mortality were analyzed. RESULTS: From 2014 to 2019, 21 patients had received BPGs at two Austrian vascular centers. Their median age was 63 years (interquartile range [IQR], 55-71 years), the patients were predominantly male (76%), and the median body mass index was 25.3 kg/m2 (IQR, 21.7-27.3 kg/m2). The major comorbidities included arterial hypertension, peripheral artery disease, smoking, and chronic pulmonary disease. The indications for surgery were vascular graft or endograft infection in 62% and aortic reconstruction in the presence of systemic infection in 38%. Three patients (14%) had aortoenteric fistulas. Surgery was technically successful in all cases. The median follow-up was 21.6 months (IQR, 6.0-34.6 months). The 30-day mortality was 9.5%. The 1- and 2-year overall survival was 84% and 75%, respectively. Of the 21 patients, 89% had remained free of recurrent infection. One of the two reinfections had resolved after treatment of the underlying focus. At 2 years, the primary and assisted primary patency rates were 86% and 94%, respectively. No limbs were lost during follow-up. CONCLUSIONS: Prefabricated BPGs represent a promising alternative for the management of aortic graft infections and aortoiliac reconstruction in the presence of systemic infection.

Preliminary results of the Austrian National Registry regarding the novel iCover bridging stent graft in fenestrated endovascular aortic repair.

OBJECTIVE: Bridging stentgrafts (BSGs) are one of the primary limiting factors regarding long-term results after fenestrated endovascular aortic repair (fEVAR). This study aims to report for the first time the outcome of a novel BSG called iCover from a national, multicentric retrospective database. METHODS: A cohort of 58 patients received 212 BSGs for the renovisceral arteries in fEVAR. Patients were followed-up clinically and with computed-tomography angiography. Study end points were mortality, occurrence of complications, technical success of the BSG implantation, defined as successful deployment with vessel patency and absence of type 1c, 3b, and 3c endoleak, and stability over the follow-up. RESULTS: Three BSG unrelated mortalities (5.1 %), four BSG unrelated major complications (6.8 %) and five minor complications (8.6 %) occurred. The technical success of iCover was 207/212 (97.6 %), target vessel patency was 100 % over a follow-up of 4.0 months, and no late BSG related endoleak was detected. In two cases, the BSG was dislodged from the balloon and could be parked in a safe position without further sequelae (0.9 %). CONCLUSION: The iCover represents a feasible BSG for fEVAR with an excellent safety profile and technical success rate in the early phase. Prudent post-dilatation and monitoring of the proximal and distal stent ends can potentially further improve outcome. Longer follow-up series are necessary.

In-Stent Restenosis in Peripheral Arterial Disease: Ultra-High-Resolution Photon-Counting Versus Third-Generation Dual-Source Energy-Integrating Detector CT Phantom Study in Seven Different Stent Types.

PURPOSE: The visualization of peripheral in-stent restenosis using energy-integrating detector CT is challenging due to deficient spatial resolution and artifact formation. This study compares the first clinically available photon-counting detector CT to third-generation dual-source energy-integrating detector CT. MATERIALS AND METHODS: Nylon cylinders with central bores (4 mm, 2 mm), mimicking 75% and 95% stenoses, were placed inside seven different 8-mm diameter stents and filled with diluted contrast medium. Phantoms were scanned with photon-counting detector CT at slice thicknesses of 0.2 mm (available only in this scanner type), 0.5 mm, and 1.0 mm versus 0.5 mm and 1.0 mm in energy-integrating detector CT at matched CT dose indices. Contrast-to-noise ratios were calculated from attenuation rates. Residual lumen size was measured as full width at half-maximum. Subjective image quality was assessed by two independent blinded raters. RESULTS: Mean contrast-to-noise ratio was lowest in photon-counting detector CT at 0.2 mm slice thickness (0%, 75%, and 95% in-stent restenosis: 6.11 ± 0.6, 5.27 ± 0.54, and 5.02 ± 0.66) and highest at 1.0 mm slice thicknesses with similar measurements in photon-counting detector CT and energy-integrating detector CT (11.46 ± 1.08, 9.94 ± 1.01, 8.26 ± 1.0 vs. 3.34 ± 1.0, 9.92 ± 0.38, 7.94 ± 1.07). Mean full width at half-maximum measurements in photon-counting detector CT at 0.2 mm slice thickness for 0%, 75%, and 95% in-stent restenosis were 8.00 ± 0.37, 3.98 ± 0.34, and 1.92 ± 0.16 mm. Full width at half-maximum was least precise in 95% in-stent restenosis at 1.0 mm slice thickness with similar measurements between scanners (1.57 ± 0.33 vs. 1.71 ± 0.15 mm). Interrater correlation coefficient was 0.75 [95% CI: [0.53; 0.86]; subjective scores were best at 0.2 mm slice thickness in photon-counting detector CT (19.43 ± 0.51 and 19.00 ± 0.68). CONCLUSION: In phantom in-stent restenosis in 8 mm stents, we observed similar full width at half-maximum for photon-counting detector CT and energy-integrating detector CT in 0% and 75% in-stent restenosis, but at 95% in-stent restenosis, FWHM tended to be more accurate in smaller slice thicknesses in both scanners. Subjective image assessment yielded best results at 0.2 mm slice thickness in photon-counting detector CT despite lower contrast-to-noise ratio.

Endovascular repair in type A aortic dissection: Anatomical candidacy for currently manufactured stent grafts and conceptual valve-carrying devices for an Endo-Bentall procedure.

OBJECTIVES: Endovascular treatment has been suggested as an alternative for open surgery for type A aortic dissection, but current devices have severe anatomical limitations. This study assesses the computed tomography-based anatomical suitability of currently manufactured stent grafts as well as 2 embodiments of valve-carrying devices. METHODS: In a retrospective single-centre cohort of 200 consecutive ascending/arch operations between 2009 and 2018, a total of 112 patients with type A aortic dissections were identified and evaluated for endovascular candidacy based on the locations of the entries, the landing zone diameters/lengths and the supra-aortic vessel origins according to the anatomical instructions for use criteria of 6 commercially available (tubular, branched or fenestrated) stent grafts. Two suggested valve-carrying devices with inner branches or fenestrations for the coronary arteries and branches for the supra-aortic vessels were also evaluated. RESULTS: The anatomical feasibility for commercial stent grafts ranged from 4% to 21%. The main limitations were proximal landing zone diameter (considering oversizing <15%), length due to dilatation and an entry too close to the sinotubular junction. For the valve-carrying conduits, anatomical feasibility was between 31% and 80%, with the main limiting factors being the diameter of the aortic annulus and its distance to the coronary arteries. CONCLUSIONS: The anatomical applicability of currently manufactured stent grafts for the treatment of type A aortic dissection is limited mainly by the absence of a suitable proximal landing zone in the ascending aorta and might substantially be improved by anchoring in the aortic annulus using a valve-carrying device that uses either fenestrations or branches for the coronary arteries.

[Fenestrated and branched endovascular aortic prostheses : An update]. / Fenestrierte und verzweigte endovaskuläre Aortenprothesen : Ein Update.

BACKGROUND: Today, complex abdominal aortic pathologies involving the visceral arteries and without an adequate proximal neck can be treated using fenestrated/branched endovascular aortic repair (FEVAR/BEVAR) with similar safety and success rates as infrarenal aortic pathologies treated with tubular EVAR. METHODICAL INNOVATIONS AND CHALLENGES: Fenestrations (if the vessel originates from a nondilated aorta) or branches (if the vessel originates from a dilated aorta) may be used for the visceral arteries. Both types of openings are sealed via bridging stent grafts that connect to the target vessel. Multiple manufacturers offer fenestrated or branched endoprostheses, with only a few being CE certified and the majority in Europe being patient-specific custom-made devices. Therefore, they require a certain delivery time which precludes acute patients from such treatment. However, two stent grafts with four branches for thoracoabdominal aneurysms are available off the shelf and are anatomically suitable for the majority of patients, thus, allowing for acute treatment. All FEVAR and BEVAR main bodies require bridging stent grafts, all of which are used off-label. RECOMMENDATIONS: As bridging stent grafts are one of the main reasons for reinterventions, one should be aware of fractures and kinking of the bridging stent grafts during follow-up and should refrain from using single-layered bridging stent grafts in BEVAR.

Use of a Steerable Sheath for Completely Femoral Access in Branched Endovascular Aortic Repair Compared to Upper Extremity Access.

PURPOSE: To compare bridging stent graft (BSG) implantation in downward oriented branches in branched endovascular aortic repair (bEVAR), using a commercially available steerable sheath from an exclusively femoral access (TFA) with traditional upper extremity access (UEA). METHODS: In a retrospective cohort study, 7 patients with 19 branches in the TFA cohort received BSG insertion using the Medtronic Heli FX steerable sheath from a femoral access, and 10 patients with 32 branches in the UEA cohort from a brachial approach. Technical success, total intervention time, fluoroscopy time, branch cannulation time, and complication rate were recorded. RESULTS: Technical success was 19/19 branches in the TFA and 31/32 in the UEA cohort. The mean branch cannulation time was considerably shorter in the TFA group (17 vs. 29 min, p = 0.003), and total intervention time tended to be shorter (169 vs. 217 min, p = 0.176). CONCLUSION: Using a commercially available steerable sheath allowed successful cannulation of all branches in this cohort and was associated with significantly shorter branch cannulation times. Potentially, this technique can lower the stroke and brachial puncture site complication risk as well as reduce total intervention time and radiation dose. LEVEL OF EVIDENCE: 2b, retrospective cohort study.

Structural failure in bridging stentgrafts for branched endovascular aneurysm repair: a case-control study.

OBJECTIVE: To present a case series of spontaneous structural failure of bridging stentgrafts (BSGs) after branched endovascular aortic repair (bEVAR), as well as their failure types and their detection. While bEVAR is a safe and effective procedure, one main limitation is the reintervention rate associated with the BSGs. Structural failure of BSGs, defined as fabric disruption, stent fracture with leak or complete separation is a major cause for reinterventions and difficult to detect in computed tomography angiography (CTA). METHODS: From a multicenter bEVAR complication database, structural BSG failures were identified. Patient and BSG characteristics, detection mode, failure type, treatment and outcome were recorded and compared with bEVAR patients with intact BSGs. RESULTS: Twenty-three BSG failures were detected in 12 patients with only 43% directly identified in CTA, after a mean of 21.4 months after implantation. The BSGs were Advanta (n = 4), E-Ventus (n = 16) and BeGraft (n = 3) in 10 renal, 9 superior mesenteric, and 4 celiac branches. Religning with another BSG was successful in 20/22 cases, one BSG failure necessitated renal branch embolization (organ loss), and one mesenteric bypass surgery. Two reintervention-related mortalities occurred. CONCLUSION: Structural failure of BSGs is a serious limitation for bEVAR, which can result in high reintervention rates and serious complications. BSG failure typically occurs in single-layer types and events are clustered in patients. The necessary reinterventions carry serious morbidity and mortality. Since the use as BSG in bEVAR is off-label with all current BSG manufacturers, caution is advised regarding patient-informed consent.

Branched versus fenestrated thoracic endovascular aortic repair in the aortic arch: A multicenter comparison.

OBJECTIVE: For thoracic endovascular aortic repair of the arch, branched and fenestrated endografts are available with different limitations regarding anatomy and extent of the pathology. Comparisons are lacking in the literature. The aim of this study was to compare the results of 2 currently commercially available devices for branched thoracic endovascular aortic repair and fenestrated thoracic endovascular aortic repair. METHODS: In a retrospective, multicenter cohort study, a consecutive patient series treated with branched thoracic endovascular aortic repair or fenestrated thoracic endovascular aortic repair for aortic arch pathologies was assessed. Baseline characteristics, procedural fenestrated thoracic endovascular aortic repair, and outcome were analyzed. Furthermore, the potential anatomic feasibility of the respective alternate device was assessed on the preoperative computed tomography scans. RESULTS: The branched thoracic endovascular aortic repair and fenestrated thoracic endovascular aortic repair cohorts consisted of 20 and 34 patients, respectively, with similar comorbidities; indication was aneurysm in 65% and 79%, penetrating aortic ulcer in 20% and 9%, and dissection in the remaining procedures, respectively. Technical success was achieved in all but 1 patient. Perioperative mortality and major stroke rate were both 10% in branched thoracic endovascular aortic repair and 0% and 3% in fenestrated thoracic endovascular aortic repair, respectively. During follow-up of 31 and 40 months, 1 branch occlusion occurred in the branched thoracic endovascular aortic repair cohort, and 2 late endoleaks occurred in the fenestrated thoracic endovascular aortic repair group. One aortic death occurred. Although 35% of patients undergoing branched thoracic endovascular aortic repair were anatomically suitable for fenestrated thoracic endovascular aortic repair, 91% of those undergoing fenestrated thoracic endovascular aortic repair were suitable for branched thoracic endovascular aortic repair. CONCLUSIONS: Both branched thoracic endovascular aortic repair and fenestrated thoracic endovascular aortic repair show excellent technical success and acceptable complication rates, whereas branched thoracic endovascular aortic repair tends toward higher morbidity, especially stroke rates. By offering fenestrated thoracic endovascular aortic repair along with branched thoracic endovascular aortic repair, aortic centers could potentially lower complication rates and simultaneously still treat a wide range of anatomies.

Pre-operative serum C-reactive protein as independent prognostic factor for survival but not infection in patients with high-grade osteosarcoma.

PURPOSE: The purpose of this study was to investigate (a) whether pre-operative serum CRP is a predictor of survival in patients with high-grade osteosarcoma, (b) whether post-operative infection is a predictor of survival in these patients and (c) whether CRP is a predictor of post-operative infection, and especially deep prosthetic infection. METHODS: In this retrospective single-centre study, pre-operative serum CRP levels in 79 patients (37 females, 42 males; average age, 18 years; mean follow-up, 46 months) undergoing resection of an osteosarcoma were correlated with clinical data and survival. RESULTS: The mean pre-operative serum CRP level of all 79 patients was 0.53 mg/dl (SD, 1.27 mg/dl). Patients dying of their underlying disease had significantly higher CRP levels compared to patients surviving throughout the follow-up period (1.09 mg/dl ± 2.02 mg/dl versus 0.32 mg/dl ± 0.75 mg/dl, respectively; p = 0.015). CRP levels were significantly correlated with survival (Pearson's correlation coefficient = -0.25; p = 0.026) and histological subtype (Pearson's correlation coefficient = -0.42; p < 0.001), but not with sex, age, histological response, tumour size or metastatic disease. In uni- and multivariate survival analysis, age, response to chemotherapy and serum CRP were associated with disease-specific survival. Patients with a CRP level over 1 mg/dl had a significantly lower disease-specific five-year survival of 36.7% compared to 73.8% in patients with normal CRP values (p = 0.020). Infection was not correlated with disease-specific survival. Pre-operative serum CRP levels were not correlated with post-operative infection or deep prosthetic infection. CONCLUSIONS: Pre-operative serum CRP seems to be an independent predictor of survival in patients with high-grade osteosarcoma. Further studies are needed to confirm these results on a large-scale basis.

Endovascular Stent-Graft Repair of the Ascending Aorta: Assessment of a Specific Novel Stent-Graft Design in Phantom, Cadaveric, and Clinical Application.

PURPOSE: To test a stent-graft specifically designed for the ascending aorta in phantom, cadaver, and clinical application, and to measure deployment accuracy to overcome limitations of existing devices. METHODS: A stent-graft has been designed with support wires to fixate the apices toward the inner curvature, thereby eliminating the forward movement of the proximal end which can happen with circumferential tip capture systems. The device was deployed in three aortic phantoms, and in four cadavers, deployment precision was measured. Subsequently, the device was implanted in a patient to exclude a pseudoaneurysm originating from the distal anastomosis after ascending aortic replacement. RESULTS: The stent-grafts were successfully deployed in all phantoms and cadavers. Deployment accuracy of the proximal end of the stent-graft was within 1 mm proximally and 14 mm distally to the intended landing zone on the inner curvature, and 2-8 mm distal to the intended landing zone on the outer curvature. In clinical application, the pseudoaneurysm could be successfully excluded without complications. CONCLUSION: The novel stent-graft design promises accurate placement in the ascending aorta. The differential deployment of the apices at the inner and outer curvatures allows deployment perpendicular to the aortic axis. LEVEL OF EVIDENCE: No level of evidence.

Perceptibility and quantification of in-stent stenosis with six peripheral arterial stent types in vitro: comparison of 16-MDCT angiography, 64-MDCT angiography, and MR angiography.

OBJECTIVE: The purpose of this study was to evaluate and compare the perceptibility of 75% and 95% in-stent stenoses with CT angiography and MR angiography using six stent types in a phantom model. MATERIALS AND METHODS: Six different stent types were placed into tubes filled with contrast agent (ioversol or gadoteric acid), and nylon cylinders (8 mm diameter) bored in the central axis (2 and 4 mm) to mimic 75% and 95% stenoses were inserted into the stents inside the tubes. CT angiography (16- and 64-MDCT scanners using three different kernels at 120 and 140 kV) and MR angiography (1.5 T) were performed. On 2-mm coronal sections, signal intensities in the stenosed stents were compared with unstenosed segments. In addition, perceptibility of the residual lumen was assessed using a subjective score. Image analysis was performed by two experienced and blinded radiologists. RESULTS: Sixteen-slice CT angiography showed relative in-stent signal intensities of 72-87%, whereas 64-MDCT angiography showed relative in-stent signal intensities of 63-99%. Sixty-four-slice CT angiography showed nearly no difference between 75% and 95% stenoses in the subjective scores. The high-contrast kernel was superior to intermediate- and low-contrast kernels. MR angiography showed relative in-stent signal intensities of 57-98%. The presence of localized artifacts and resulting inhomogeneous luminal signal caused lower subjective perceptibility ratings than the objective score would suggest. CONCLUSION: CT angiography was superior in the differentiation between 95% stenoses and occlusions. 64-MDCT angiography was superior to 16-MDCT (mean +/- SD, 83.0 +/- 2.9 vs 78.3 +/- 3.3; p = 0.006), especially with high-contrast kernels (89.7 +/- 2.1 vs 78.3 +/- 3.3; p = 0.001). For detection of 75% stenoses, MR angiography seems to be suitable subjectively, even though no statistical significance was found.

Quantification and detectability of in-stent stenosis with CT angiography and MR angiography in arterial stents in vitro.

OBJECTIVE: The purpose of this study was to compare CT angiography (CTA) and MR angiography (MRA) for the detectability of 75% and 95% stenoses in phantoms using six different stents. MATERIALS AND METHODS: Six different stents (Expander, Hemobahn, SelfX, Smart, Symphony, and Wallstent) were inserted into tubes filled with contrast agent (ioversol or gadoteric acid). To mimic stenoses of 75% and 95% of the patent lumen, 8-mm-diameter nylon cylinders were bored in the central axis (2 mm and 4 mm, respectively) and placed into the stent lumen. Intensity profiles across stenoses on 2-mm coronal reformatted sections of CTA or MRA were compared, and the detectability of the residual lumen was assessed using a subjective score. RESULTS: CTA showed relative in-stent signal attenuation for the in-stent stenoses of the tested stents ranging from 75% to 100% of the signal intensity of the control. SelfX and Symphony showed further shading of the residual lumen due to beam-hardening artifacts. Overestimation of stenosis was associated with low-grade stenoses in which the border of the lumen was closer to the stent struts. MRA showed relative in-stent signal attenuation of the in-stent stenoses ranging from 30% to 100% of the signal intensity of the control. Strut thickness tended to correlate with higher attenuation at CT. CONCLUSION: CTA may be more suitable for differentiation between 95% stenosis and occlusion; MRA has higher sensitivity in detecting 75% stenoses. Strut thickness and mesh size did not prove to be significant predictors for signal attenuation or overall image quality.

Self-expanding nitinol stents of high versus low chronic outward force in de novo femoropopliteal occlusive arterial lesions (BIOFLEX-COF trial): study protocol for a randomized controlled trial.

BACKGROUND: Self-expanding nitinol stents must be oversized at least by a minimal amount to ensure contact with the vessel wall and prevent migration. Once the stent is deployed it exerts a continuous force upon the vascular wall, termed chronic outward force (COF). Animal studies have found an increased neointimal hyperplasia in stents with high oversizing and thus high COF. Data about correlation between COF and neointimal hyperplasia in humans are currently lacking. The objective of the BIOFLEX-COF trial is to prospectively investigate differences in formation of intimal hyperplasia at 1 and 2 years after implantation of nitinol stents with high versus low COF in de novo femoropopliteal occlusive arterial lesions. METHODS: The BIOFLEX-COF trial is a prospective, quantitative, randomized study. Eighty subjects with symptomatic peripheral arterial lesions eligible for endovascular stent implantation will be enrolled and randomly assigned to either a high COF group (LifeStent Flexstar, Bard Peripheral Vascular Inc., Tempe, AZ, USA) or low COF group (Pulsar, Biotronik AG, Bülach, Switzerland) using an online randomization program to generate a random 1:1 group allocation (block randomization). After implantation and dilatation, COF at every 2 mm along the stent axis will be calculated from the actual stent diameter versus its nominal diameter. There will be two follow-up evaluations at 12 and 24 months. Primary endpoint is the amount of in-stent neointima at 1 year, assessed by contrast-enhanced CT angiography (CTA). In the control examinations, stent diameter and true lumen diameter will be measured on DICOM images every 2 mm along the stent axis to quantify the relative amount of in-stent restenosis. Secondary objectives are the amount of in-stent neointima at 2 years, device- and procedure-related adverse events and target lesion revascularization (TLR) rate. The scheduled time for recruitment is 2 years. Recruitment is expected to be complete in October 2017. DISCUSSION: This trial is the first to prospectively investigate the influence of COF on stent patency. If successful, the results will aid in a more precise selection of stent type and size in a given target vessel. The present study is challenging in that it compares two different self-expanding nitinol stents head-to-head against each other. To optimize the power of this study, traditional binary outcome parameters such as TLR and restenosis at Doppler ultrasound were dropped as primary endpoints. Instead, the amount of neointima inside the stent accessed by CTA was selected as (continuous) outcome parameter. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03097679 . Date of registration: 14 March 2017 (retrospectively registered).

Influence of spectacle-related changes in retinal image size on contrast sensitivity function after laser in situ keratomileusis.

PURPOSE: To evaluate changes in contrast sensitivity after laser in situ keratomileusis (LASIK) for the correction of myopia using a monitor-based method and considering the preoperative minification effect of high-diopter spectacles. SETTING: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. METHODS: Fifteen eyes of 11 patients had LASIK to correct myopia. The best corrected visual acuity (BCVA) and contrast sensitivity function (CSF) were measured preoperatively and 1, 3, and 6 months postoperatively using the AcuityMax (Science 2020) computer program. The error in contrast sensitivity measurement due to different angular sizes of the test figures deriving from the spectacle refractions before and after LASIK were considered. RESULTS: Preoperatively, and at 1, 3, and 6 months, the mean Snellen BCVA was 0.93 +/- 0.19 (SD), 0.80 +/- 0.26, 0.85 +/- 0.21, and 0.84 +/- 0.27, respectively. The best mean CS (measured at 1.1 logMAR) was 1.17 +/- 0.05, 1.12 +/- 0.07, 1.13 +/- 0.08, and 1.18 +/- 0.04, respectively. The strongest CS changes were observed at 0.7 logMAR (6 cycles per degree), where CS was 1.10 +/- 0.07 preoperatively and 1.06 +/- 0.09, 1.07 +/- 0.12, and 1.14 +/- 0.07, at 1 month, 3 months, and 6 months, respectively. With correction for the spectacle effect, the preoperative CS was approximately 3% higher and CS at 3 months for intermediate optotype sizes was significantly inferior to preoperatively. CONCLUSIONS: With correction of different retinal image sizes before and after LASIK (due to different spectacle refraction), the CS was significantly below the preoperative values at 1 and 3 months and approached the preoperative values at 6 months. The proposed method is potentially capable of quality monitoring and method comparisons after photorefractive surgery.

MR imaging of the her2/neu and 9.2.27 tumor antigens using immunospecific contrast agents.

Molecular imaging of tumor antigens using immunospecific magnetic resonance (MR) contrast agents is a rapidly evolving field, which can potentially aid in early disease detection, monitoring of treatment efficacy, and drug development. In this study, we designed, synthetized, and tested in vitro two novel monocrystalline iron oxide nanoparticles (MION) conjugated to antibodies against the her2/neu tyrosine kinase receptor and the 9.2.27 proteoglycane sulfate. MION was synthetized by coprecipitation of iron II and iron III salts in 12-kD dextran solution; antibody coupling was performed by reductive amination. The relaxivity of the conjugates was 24.1-29.1 mM(-1) s(-1), with 1.8 to 2.1 antibody molecules per nanoparticle. A panel of cultured melanoma and mammary cell lines was used for testing. The cells were incubated with the particles at 16-32 microg Fe/ml in culture medium for 3 h at 37 degrees C, and investigated with immune fluorescence, transmission electron microscopy (TEM), MRI of cell suspensions in gelatine, and spectrophotometric iron determination. All receptor-positive cell lines, but not the controls, showed receptor-specific immune fluorescence, and strong changes in T(2) signal intensity at 1.5 T. The changes in 1/T(2) were between 1.5 and 4.6 s(-1) and correlated with the amount of cell-bound iron (R = 0.92). The relaxivity of cell-bound MION increased to 55.9 +/- 10.4 mM(-1) s(-1). TEM showed anti-9.2.27 conjugates binding to the plasma membrane, while the anti-her2/neu conjugates underwent receptor-mediated endocytosis. In conclusion, we obtained receptor-specific T(2) MR contrast with novel covalently bound, multivalent MION conjugates with anti-9.2.27 and anti-her2/neu to image tumor surface antigens. This concept can potentially be expanded to a large number of targets and to in vivo applications.

Colonic adenocarcinomas: near-infrared microcatheter imaging of smart probes for early detection--study in mice.

PURPOSE: To prospectively evaluate the ability of micro-fiberoptic catheters, which simultaneously record white light and near-infrared (NIR) images, to reveal colonic neoplasms after the intravenous administration of activatable "smart" probes that increase in NIR fluorescence subsequent to protease activation. MATERIALS AND METHODS: The institutional animal care committee approved all animal experiments. CT26 tumor cells were orthotopically implanted into the descending colon of C57BL6/J mice (n=10). Thirteen days later, mice intravenously received either 2 nmol of a protease-sensing probe that had cathepsin B as a major activator (n=5) or saline (control animals [n=5]). One day later, animals were noninvasively examined to the point of the splenic flexure by using microcatheter imaging. Excised colons were subsequently evaluated with epifluorescence imaging, histologic examination, and cathepsin B immunohistochemistry. Student t test was used for statistical analysis, with P<.05 considered to indicate a significant difference. RESULTS: Results with fiberoptic imaging demonstrated that all tumors were visible with the protease-activatable probe, even when they were not readily apparent at white light imaging. A target-to-background ratio (TBR) of 8.86 for tumor to adjacent normal mucosa was achieved in the NIR channel after probe administration (P=.001), whereas white light images resulted in a TBR of 1.14 (P>.5) based on luminosity. The tumoral NIR fluorescence intensity was more than 30-fold greater in probe-injected animals than in control animals, indicating that essentially all of the signal recorded in lesions was from activatable probe administration. Results of immunohistochemistry confirmed cathepsin B overexpression in the tumor compared with adjacent mucosa. CONCLUSION: The use of NIR imaging microcatheters combined with protease-activatable smart probes results in a beacon effect that highlights tumors with high TBRs; this technique thus may be a potentially useful adjunct to white light colonoscopy in the future.