BMI-Adapted Double Low-Dose Dual-Source Aortic CT for Endoleak Detection after Endovascular Repair: A Prospective Intra-Individual Diagnostic Accuracy Study

PURPOSE

To assess the diagnostic accuracy of BMI-adapted, low-radiation and low-iodine dose, dual-source aortic CT for endoleak detection in non-obese and obese patients following endovascular aortic repair.

METHODS

In this prospective single-center study, patients referred for follow-up CT after endovascular repair with a history of at least one standard triphasic (native, arterial and delayed phase) routine CT protocol were enrolled. Patients were divided into two groups and allocated to a BMI-adapted (group A, BMI < 30 kg/m2; group B, BMI ≥ 30 kg/m2) double low-dose CT (DLCT) protocol comprising single-energy arterial and dual-energy delayed phase series with virtual non-contrast (VNC) reconstructions. An in-patient comparison of the DLCT and routine CT protocol as reference standard was performed regarding differences in diagnostic accuracy, radiation dose, and image quality.

RESULTS

Seventy-five patients were included in the study (mean age 73 ± 8 years, 63 (84%) male). Endoleaks were diagnosed in 20 (26.7%) patients, 11 of 53 (20.8%) in group A and 9 of 22 (40.9%) in group B. Two radiologists achieved an overall diagnostic accuracy of 98.7% and 97.3% for endoleak detection, with 100% in group A and 95.5% and 90.9% in group B. All examinations were diagnostic. The DLCT protocol reduced the effective dose from 10.0 ± 3.6 mSv to 6.1 ± 1.5 mSv (p < 0.001) and the total iodine dose from 31.5 g to 14.5 g in group A and to 17.4 g in group B.

CONCLUSION

Optimized double low-dose dual-source aortic CT with VNC, arterial and delayed phase images demonstrated high diagnostic accuracy for endoleak detection and significant radiation and iodine dose reductions in both obese and non-obese patients compared to the reference standard of triple phase, standard radiation and iodine dose aortic CT.

Protected and Unprotected Radiation Exposure to the Eye Lens During Endovascular Procedures in Hybrid Operating Rooms

OBJECTIVE

Radiation cataract has been observed at lower doses than previously thought, therefore the annual limit for equivalent dose to the eye lens has been reduced from 150 to 20 mSv. This study evaluated radiation exposure to the eye lens of operators working in a hybrid operating room before and after implementation of a dose reduction program.

METHODS

From April to October 2019, radiation exposure to the first operator was measured during all consecutive endovascular procedures performed in the hybrid operating room using BeOSL H_p(3) eye lens dosimeters placed both outside and behind the lead glasses (0.75 mm lead equivalent). Measured values were compared with data from a historic control group from the same hospital before implementation of the dose reduction program.

RESULTS

A total of 181 consecutive patients underwent an endovascular procedure in the hybrid operating room. The median unprotected eye lens dose (outside lead glasses) of the main operator was 0.049 mSv for endovascular aortic repair (EVAR) (n = 30), 0.042 mSv for thoracic endovascular aortic repair (TEVAR) (n = 23), 0.175 mSv for complex aortic fenestrated or branched endovascular procedures (F/BEVAR; n = 15), and 0.042 mSv for peripheral interventions (n = 80). Compared with the control period, EVAR had 75% lower, TEVAR 79% lower, and F/BEVAR 55% lower radiation exposure to the unprotected eye lens of the first operator. The lead glasses led to a median reduction in the exposure to the eye lens by a factor of 3.4.

CONCLUSION

The implementation of a dose reduction program led to a relevant reduction in radiation exposure to the head and eye lens of the first operator in endovascular procedures. With optimum radiation protection measures, including a ceiling mounted shield and lead glasses, more than 440 EVARs, 280 TEVARs, or 128 FEVARs could be performed per year before the dose limit for the eye lens of 20 mSv was reached.

[Endovascular aortic repair: the hostile aneurysm neck : Morphologic definition, impact on long-term outcome, and treatment options]

DEFINITION

A hostile neck is defined by various anatomical conditions that describe a morphology of the proximal aneurysmal neck of infrarenal aortic aneurysms that is unfavorable for endovascular treatment (endovascular aortic repair, EVAR): proximal landing zone length ≤ 15 mm, angulation of the aortic neck > 60°, conical aortic neck, diameter of the aortic neck > 32 mm, and circumferential calcification/thrombus.

EFFECTS ON OUTCOME

These morphological parameters are not only associated with a higher perioperative technical failure rate (primary type 1 endoleak) but also with poorer long-term results (secondary type 1 endoleak) and thus a higher reintervention rate in standard EVAR, so that standard EVAR should be reserved for a few exceptions in these cases.

TREATMENT OPTIONS

Due to the rapid development of endovascular techniques in the last decade, we now have a variety of endovascular options for aneurysms with hostile necks, for both elective treatment and emergency care, in addition to conventional open surgery, which is still the standard method in many cases and is currently undergoing a renaissance: fenestrated endovascular aortic repair (FEVAR) as the method of first choice in the elective setting, EVAR with chimneys (ChEVAR), endosuture aneurysm repair (ESAR). An important option is the conservative approach, which can be a reasonable choice if the patient's preference is taken into account and a careful risk-benefit assessment is performed.

Real-world data of popliteal artery aneurysm treatment. Analysis of the POPART registry

OBJECTIVE

Popliteal artery aneurysm (PAA) is a rare disease with a prevalence of 0.1-1%. Within the last years, endovascular repair of PAA (ER) has been performed more frequently despite the lack of high-level evidence compared to open surgery (OR). In 2014, the POPART registry was initiated to validate current treatment options in PAA repair.
 METHOD: POPART is a multinational multicenter registry for peri- and postoperative outcome of endovascular and open PAA repair. Data sets are recorded by the online survey tool "SurveyMonkey®". Regular monitoring and plausibility checks of the data sets are performed to ensure reliability. The aim of this study is to present results of the POPART registry, with data of 41 centers.
 RESULTS: From June 2014 to August 2019, a total of 794 cases were recorded in the PAA registry. OR was performed in 662 patients and ER in 106 patients; 23 Patients were treated conservatively. Four of the 106 patients with primary ER underwent conversion to OR. ER patients were significantly older (ER x˜= 71 vs. OR x˜= 67 (p<0.05). There were no other significant differences in demographics or comorbidities and aneurysm morphology between the two groups. 50.3% patients in the OR group were symptomatic; in the ER group 29.2% (p<0.05). Emergency treatment for acute ischemia, critical ischemia or rupture was necessary in 149 patients (22.5%) in the OR group vs. 11 patients (10.3%) in the ER group.
Most frequent complications after surgery were impaired wound healing (OR n=47, 7.1%; ER n=3, 2.8%, p>0.05) and major bleeding (OR n=26, 3.9%; ER n=3, 2.8%, p>0.05). In-hospital length of stay (= 10d [3-65] OR vs. x˜=7d [1-73] ER) was significantly higher in the OR group. Overall patency was 83.2% vs. 44.7% (OR/ER, p<0.005) after 12 months and 74.2% vs. 29.1% (OR/ER, p<0.005) after 24 months. There was a significantly poorer outcome for prosthetic graft compared to autologous vein in the OR group (71.4% vs. 88.1% 12-month primary patency).
 CONCLUSION: 
 In order to evaluate new treatment techniques such as endovascular repair (ER) for PAA, real world data is of essential importance. This analysis of the first results for the POPART registry shows good perioperative results for endovascular treatment of PAA in asymptomatic patients with good outflow vessels. The perioperative complication rate is low and the postoperative hospital stay is shorter than after OR. However, the patency rates after 12 and 24 months are low in the ER group compared to patients treated with open repair. More follow-up data is required for further interpretation; the completion of the data sets in the registry is ongoing.

The zone 2 concept and distal stent graft positioning in TH 2-3 are associated with high rates of secondary aortic interventions in frozen elephant trunk surgery

OBJECTIVES

The goal of this study was to investigate the association between the localization of the distal anastomosis (zone 2/3), the stent graft length (100-160 mm), the position of the distal end of the hybrid prosthesis and the need for secondary aortic intervention (SAI) in acute and chronic thoracic aortic disease after the frozen elephant trunk procedure.

METHODS

From 2009 through 2020, a total of 232 patients (137 men; mean age, 61.7 ± 13.8 years) were treated with the frozen elephant trunk procedure. The main indications were acute aortic dissection type A (n = 106, 46%), chronic aortic dissection type A (n = 52, 22%) and degenerative thoracic aortic aneurysm (n = 74, 32%).

RESULTS

The rate of SAI was significantly higher when we performed a distal anastomosis in zone 2 rather than in zone 3, whereas the rate of SAI was less frequent if the distal positioning of the hybrid prosthesis was below TH 4-5. Combining the zone 2 concept and the short stent graft length (100 mm) was associated with a significantly higher rate of SAIs. Patients with a distal anastomosis in zone 2 were significantly less likely to have a recurrent laryngeal nerve injury (P < 0.001). However, no association between a specific arch zone of a distal anastomosis and the occurrence of spinal cord injury was observed.

CONCLUSIONS

Rates of SAIs are highest in patients who were treated with a distal anastomosis in zone 2 and a short stent graft (100 mm) with the distal end of the hybrid prosthesis at vertebral level TH 2-3.

Protected and unprotected radiation exposure to the eye lens of vascular surgeons during endovascular procedures in hybrid operating rooms

Objective

Radiation induced cataract has been observed at lower threshold doses than expected. Therefore, the annual limit for equivalent dose to the eye lens has been reduced from 150 to 20 mSv. We aimed to evaluate radiation exposure to the eye lens of vascular surgeons working in a hybrid operating room before and after a dose reduction program was established.

Methods

Prospective non-randomized trial with a historic control group. From April – October 2019, radiation exposure to the operator was measured during all endovascular procedures performed in the hybrid operating room using BeOSL Hp(3) eye lens dosimeters placed outside the 0.75mm lead equivalent glasses on the side of the radiation source and behind the lead glasses. Measured values were compared to data from a prospective study performed at the same center in the years of 2012 and 2013 before a dose reduction program had been implemented.

Results

A total of 181 consecutive patients underwent an endovascular procedure in the hybrid operating room. The mean unprotected eye lens dose of the main operator was 0.119 mSv for EVAR (n = 30), 0.118 mSv for TEVAR (n = 23), 0.312 mSv for more complex aortic procedures (F/BrEVAR; n = 15) and 0.046 mSv for peripheral interventions.

Compared to the control period, EVAR had 75% lower, TEVAR 79% lower and more complex aortic procedures 55% lower radiation exposure unprotected eye lens of the operator. The 0.75 mm lead equivalent glasses led to a median reduction of the exposure to the eye lens by the factor 3.43. Behind the lead glasses at the level of the eye lens, radiation exposure exceeding the detection limit of 0.042 mSv was measured only in 22 of 181 cases. There was a significant correlation between DAP between both protected and unprotected eye lens dose (p &lt; 0.0001, r2 = 0.512 and 0.282). DAP correlated significantly with patients’ body mass index, operating time, fluoroscopy time and digital subtraction angiography time.

Conclusion

The dose reduction program at our institution has led to a relevant reduction of the radiation dose to the head and the eye lens of the main operator in endovascular procedures. With optimum radiation protection measures including a ceiling-mounted shield and 0.75 mm lead equivalent glasses, more than 440 EVARs, 280 TEVARs or 128 FEVARs could be performed per year until the dose limit for the eye lens of 20 mSv would be reached.

Room staff radiation dose in a vascular surgery hybrid operating room and evaluation of a real-time radiation dosimeter

Objective

Real-time radiation dosimeter have been shown to decrease radiation exposure of the staff. This effect is mainly explained by increased awareness of the radiation due to direct radiation exposure feedback to the operator. We aimed to measure the radiation exposure of all staff members working in a hybrid operating room and wanted to compare the equivalent doses of real-time radiation dosimeters with thermoluminescence dosimeters.

Methods

Prospective non-randomized comparative trial. From April – October 2019, all staff members working in a hybrid operating room were equipped with real-time radiation dosimeters (Unfors RaySafe i3). The table positions of all staff members were documented. In addition, the first operator was equipped with a thermoluminescence Hp(3) eye lens dosimeter (TLD) placed outside the lead glasses to validate the real-time radiation dosimeter.

Results

The median dose of the operator / the first assistant was 73.6 µSv / 21.8 µSv for EVAR (n = 30); 57.25 µSv / 18.2 µSv for TEVAR (n = 23); 207.0 µSv / 76.65 µSv for more complex aortic procedures (f/bEVAR etc.; n = 15); 14.85 µSv / 8.5 µSv for occlusive disease of the iliac arteries (n = 27) and 6.1 µSv / 3.4 µSv for occlusive disease of the peripheral arteries (n = 53). The anesthesiologist’s median dose was 0.3 µSv, with highest values in f/bEVAR (3.9µSv). The scrub nurse’s median dose was 2 µSv with highest values in f/bEVAR (24 µSv). The position of any staff member at the left arm for transbrachial cannulation in f/bEVAR was associated with higher median equivalent radiation doses compared to the right femoral position (272.5 vs. 207 µSv for the operator (p=ns), 175.3 vs. 27.8 µSv for the first assistant (p = 0.027) and 45.55 vs. 8.0 µSv for the scrub nurse (p = 0.14)). The equivalent doses of the TLD and RaySafe did not correlate well using simple lineal regression analysis (r2 0.1713, p = 0.0014).

Conclusion

With the RaySafe real-time radiation dosimeter, table positions with increased radiation exposure can be identified. This allows for improvement in shielding at these positions, possibly leading to lower radiation exposure of the staff.

TEVAR Following FET: Current Outcomes of Rendezvous Procedures in Clinical Practice

BACKGROUND

 The treatment of extensive thoracic/thoracoabdominal aortic pathologies with arch involvement remains a challenging task in aortic surgery. The introduction of the frozen elephant trunk (FET) technique offered a link between open surgery and thoracic endovascular aortic repair (TEVAR). Despite a decade of experience, data on the complementary use of these techniques are scant. The aim of this study was to evaluate TEVAR following FET in clinical reality.

METHODS

 Between November 2006 and June 2018, 20 patients (9 females; median age of 69 years) underwent endovascular second-stage completion after FET. The clinical outcomes, technical feasibility, and morphological findings were analyzed retrospectively.

RESULTS

 Eleven of the 20 interventions were intended "rendezvous procedures" in a multistage approach; 4 were elective reinterventions, and 5 were emergency complication repairs. The median interval between FET and TEVAR was 231 days (11 days-7.4 years). The technical success rate was 100%. During a median follow-up (FU) period of 58.3 months, the overall survival rate was 95%, with one in-hospital death. Neurological complications occurred in three cases (spinal cord injury: n = 1; stroke: n = 2). Computed tomography angiography showed overall regression in the median diameter of the proximal descending aorta (from 57 to 48.5 mm).

CONCLUSION

 TEVAR as a second-stage intervention after FET is a feasible option, with satisfactory results at medium-term FU. In extensive thoracoabdominal aortic disease without proximal landing zones, the complementary use of both techniques in a multistage approach should be considered.

[Macroangiopathy in diabetes mellitus]

Peripheral artery occlusive disease is a prevalent but underdiagnosed manifestation in patients with diabetes and also in patients with diabetic foot ulceration. There is insufficient awareness of its clinical manifestations, including intermittent claudication and critical limb ischemia and of its risk of adverse limb outcomes. This review aims to highlight essential elements of the prevalence of peripheral artery disease in patients with diabetes and the the pathway of clinical diagnosis. We report the actual standards and evidence based, interdisciplinary management including conservative, interventional and surgical treatment options and also the needs of follow-up care.

Preliminary results of spot-stent grafting in Stanford type B aortic dissection and intramural haematoma

OBJECTIVES

METHODS

Patients undergoing thoracic endovascular aortic repair (TEVAR) for acute/subacute aortic dissection Stanford type B/intramural haematoma Stanford type B between 1997 and 2018 were identified from a prospectively maintained institutional database. In a total of 183 cases, 22 patients (7 women; median age 62 years; range 35–79 years) received SSG. The primary study end point was technical success. The primary morphological end point was false lumen thrombosis/aortic remodelling. Secondary end points were TEVAR-related mortality/morbidity and reinterventions. The median follow-up was 28.5 months (5 days–15.6 years).

RESULTS

The primary technical success rate was 100% (22/22). During follow-up, false lumen thrombosis was seen in 21 patients (95.5%) at a median of 6 days (0 days to 2.7 years) after the index procedure (limited/extended false lumen thrombosis: n = 9 vs 12). Aortic remodelling was achieved in 15 of 22 patients (68.2%) at a median of 360 days (3 days to 7.2 years). Limited/extended remodelling was observed in 8/15 and 7/15, respectively. Retrograde dissection or stent graft-induced new entry was not observed. No stroke or spinal cord injury occurred. Reinterventions were performed in 4/22 cases. The in-hospital mortality and 30-day mortality were 0%. Overall mortality during the follow-up period was 22.7% (5/22).

CONCLUSIONS

This study shows favourable technical and morphological results for SSG in selected patients with acute/subacute aortic dissection Stanford type B/intramural haematoma Stanford type B. Patient allocation to SSG remains individual. Prospective large-scale long-term data may allow refinement of the application.

Two-dimensional-three-dimensional registration for fusion imaging is noninferior to three-dimensional- three-dimensional registration in infrarenal endovascular aneurysm repair

BACKGROUND

Fusion imaging is a tool for intraoperative three-dimensional (3D) guidance in endovascular aneurysm repair (EVAR). In many aortic centers, the registration for location is based on an intraoperative 3D dataset acquired by means of cone-beam computed tomography (3D-3D registration). Another registration method is based on two two-dimensional (2D) images (lateral and posteroanterior) acquired with the use of intraoperative fluoroscopy for registration with a computed tomographic angiogram (2D-3D registration). The aim of the present study was to compare 2D-3D registration with 3D-3D registration regarding noninferiority in accuracy and to describe radiation exposure and ease of use of both modalities.

METHODS

From December 2014 to September 2015, 50 sequentially enrolled patients received EVAR with the use of fusion imaging using 2D-3D registration. No adjustments were made until the first angiography with inserted stent graft. The deviation of fusion imaging to the actual position of the lower renal artery compared with digital subtraction angiography was measured. A historic cohort of 101 patients treated with EVAR and fusion imaging with 3D-3D registration (3D-3D cohort) served as the control group for this study.

RESULTS

Craniocaudal deviation did not differ significantly (4.6 ± 4.4 mm in the 2D-3D cohort vs 3.6 ± 3.9 mm in the 3D-3D cohort; P = .17). The difference of the means was 1.05 mm with a 95% confidence interval of -2.45 to 0.34 and a P value for the noninferiority test of .0249, indicating that 2D-3D registration was noninferior in terms of a margin of δ = 2.5 mm. 2D-3D registration was significantly faster with significantly less additional radiation necessary: 0.45 ± 0.28 vs 45.7 ± 9.1 Gy·cm² in the 3D-3D cohort (P < .001); 2.3 ± 1.3 vs 5.3 ± 4.3 minutes in the 3D-3D cohort (P < .001).

CONCLUSIONS

Fusion imaging during EVAR with the use of 2D-3D registration is feasible in routine EVAR. Our findings of two consecutive cohorts with the same clinical, hardware, and software setup used for the procedures underscore that the accuracy of 2D-3D registration is noninferior to that of a 3D-3D registration workflow, with advantages in terms of radiation exposure, intraoperative time demand, and ease of use.

Long-term results after open repair of inflammatory infrarenal aortic aneurysms

OBJECTIVE

The objective of this study was to investigate the long-term outcome after open repair of inflammatory infrarenal aortic aneurysms.

METHODS

A total of 62 patients (mean age, 68.9 ± 8.8 years; 91.9% male) undergoing open surgery for inflammatory aortic aneurysm from 1995 until 2014 in a high-volume vascular center were retrospectively evaluated. The patients' demographics, preoperative and postoperative clinical characteristics, imaging measurements, and procedural data were collected. Study end points were preoperative and postoperative sac diameter, evolution of periaortic fibrosis and development of hydroureteronephrosis detected by computed tomography (CT) scan, and mortality and morbidity after 30 days and at the time of maximum follow-up.

RESULTS

The mean abdominal aortic aneurysm diameter was 67.3 ± 16.7 mm. A total of 30 patients (48.4%) were asymptomatic, 27 patients (43.5%) were symptomatic, and 5 patients (8.1%) were treated for ruptured aneurysm. In 25 patients (40.3%), an aorta-aortic tube graft was implanted; in 37 patients (59.7%), an aortic bifurcation graft was used. Median operating time was 208 minutes (range, 83-519 minutes). Median aortic clamping time was 31 minutes (range, 14-90 minutes); in 25 patients (40.3%), suprarenal aortic cross-clamping was necessary. Hydroureteronephrosis was preoperatively diagnosed by CT scan in 16 patients (25.8%), with the need for a ureteral stent in 11 patients (17.7%). Aneurysm- and procedure-associated 30-day mortality was 11.3% (n = 7), with septic multiple organ failure in four patients and cardiac arrest in three patients. The overall perioperative complication rate was 33.9% (n = 21 patients). Median follow-up was 71.0 months (range, 0.2-231.6 months). At 1 year, 2 years, 4 years, and 6 years, overall survival was 83.4%, 79.6%, 79.6%, and 72.6%, respectively. Six patients (9.7%) required a reintervention during follow-up, predominantly aneurysm related and caused by aortoenteric fistula and graft infection (three of five patients). Median maximum thickness of preoperative perianeurysmal inflammation on CT was 10 mm (range, 2-22 mm), which decreased in 15 of 16 (94%) patients with available postoperative CT scans. Postoperative median thickness of perianeurysmal inflammation on CT was 6 mm (range, 0-13 mm). Hydroureteronephrosis persisted in two of nine (22.2%) patients at the end of follow-up.

CONCLUSIONS

Surgery in patients with inflammatory abdominal aortic aneurysms is associated with a substantial amount of perioperative complications. After surgery, the perianeurysmal inflammation decreases in most patients on follow-up CT. However, because the inflammatory process does not totally resolve, patients require lifelong surveillance for hydroureteronephrosis and development of aortoenteric fistulas.

How Precise Are Preinterventional Measurements Using Centerline Analysis Applications? Objective Ground Truth Evaluation Reveals Software-Specific Centerline Characteristics

PURPOSE

To evaluate different centerline analysis applications using objective ground truth from realistic aortic aneurysm phantoms with precisely defined geometry and centerlines to overcome the lack of unknown true dimensions in previously published in vivo validation studies.

METHODS

Three aortic phantoms were created using computer-aided design (CAD) software and a 3-dimensional (3D) printer. Computed tomography angiograms (CTAs) of phantoms and 3 patients were analyzed with 3 clinically approved and 1 research software application. The 3D centerline coordinates, intraluminal diameters, and lengths were validated against CAD ground truth using a dedicated evaluation software platform.

RESULTS

The 3D centerline position mean error ranged from 0.7±0.8 to 2.9±2.5 mm between tested applications. All applications calculated centerlines significantly different from ground truth. Diameter mean errors varied from 0.5±1.2 to 1.1±1.0 mm among 3 applications, but exceeded 8.0±11.0 mm with one application due to an unsteady distortion of luminal dimensions along the centerline. All tested commercially available software tools systematically underestimated centerline total lengths by -4.6±0.9 mm to -10.4±4.3 mm (maximum error -14.6 mm). Applications with the highest 3D centerline accuracy yielded the most precise diameter and length measurements.

CONCLUSION

One clinically approved application did not provide reproducible centerline-based analysis results, while another approved application showed length errors that might influence stent-graft choice and procedure success. The variety and specific characteristics of endovascular aneurysm repair planning software tools require scientific evaluation and user awareness.

Perioperative cerebrospinal fluid drainage for the prevention of spinal ischemia after endovascular aortic repair

Endovascular treatment of thoracic and thoracoabdominal aortic diseases is accompanied by a risk of spinal ischemia in 1-19% of patients, depending on the entity and extent of the disease. The use of perioperative drainage of cerebrospinal fluid is one of the invasive measures to reduce the occurrence of this severe complication. This article reviews the incidence of spinal ischemia, its risk factors, the evidence for carrying out cerebrospinal fluid drainage and its modern use by means of an automated, pressure controlled system (LiquoGuard®7).

Extended use of endovascular aneurysm sealing for ruptured abdominal aortic aneurysms

Endovascular repair of abdominal aortic aneurysms (EVAR) is now an established treatment modality for suitable patients presenting with aneurysm rupture. EVAR for ruptured aneurysms reduces transfusion, mechanical ventilation, intensive care. and hospital stay when compared with open surgery. In the emergency setting, however, EVAR is limited by low applicability due to adverse clinical or anatomical characteristics and increased need for reintervention. In addition, ongoing bleeding from aortic side branches post-EVAR can cause hemodynamic instability, larger hematomas, and abdominal compartment syndrome. Endovascular aneurysm sealing, based on polymer filling of the aneurysm, has the potential to overcome some of the limitations of EVAR for ruptured aneurysms and to improve outcomes. Recent literature suggests that endovascular aneurysm sealing can be performed with early mortality similar to that of EVAR for ruptured aortic aneurysms, but experience is limited to a few centers and a small number of patients. The addition of chimney grafts can increase the applicability of endovascular aneurysm sealing in order to treat short-neck and juxtarenal aneurysms as an alternative to fenestrated endografts. Further evaluation of the technique, with larger longitudinal studies, is necessary before advocating wider implementation of endovascular aneurysm sealing in the emergency setting.

Fusion Imaging to Support Endovascular Aneurysm Repair Using 3D-3D Registration

Purpose: To evaluate the feasibility and accuracy of fusion imaging (FI) during endovascular aneurysm repair (EVAR). Methods: FI was performed in 101 consecutive EVAR patients (median age 72 years; 93 men) using automatic registration of the preoperative computed tomography angiography (CTA) with an intraoperative noncontrast cone beam CT (nCBCT; 3D-3D registration). Operative landmarks defined on the CTA were then overlaid in 3 dimensions on fluoroscopy images. Accuracy was measured as the deviation of the position of the lowest renal artery between the FI and angiography. Factors potentially influencing accuracy (α angle, β angle, anesthesia, tortuosity index, neck calcification, neck length, CTA slice thickness, and conventional or sac sealing stent-graft) were analyzed in a multivariate linear regression model. Results: Median procedure time for nCBCT was 3 minutes (range 2–20), with 4 minutes (range 0.4–15) for registration. An automatic registration tool was used successfully in 90 (89%) patients. Median craniocaudal deviation of the FI was 3 mm (range 0–15). Full accuracy (<1-mm deviation) was seen in 23 (23%) patients, 1- to 3-mm deviation in 23 (23%), 4- to 5-mm deviation in 22 (22%), and >5-mm deviation in 33 (33%). Caudal deviation potentially resulting in renal coverage was seen in 9 (9%). Lateral plus craniocaudal deviation was a median 5.8 mm (range 0–22). The position of the lowest renal artery compared to the FI was left and cranial in 62 (61%). Aneurysm morphology (β angle, p=0.04), CTA slice thickness (p=0.02), and the use of 2 stiff guidewires in endovascular aneurysm sealing (p=0.01) influenced the overlay accuracy. Conclusion: Fusion imaging can be integrated into a daily workflow adding little to the procedure time. Craniocaudal accuracy (<5 mm) was achieved in 68% of cases, allowing optimal C-arm and angiographic catheter positioning or cannulation of target vessels in most patients. However, the accuracy of FI does not allow a noncontrast EVAR procedure without confirmation of FI overlay by a minimal contrast injection or vessel cannulation.

Comparison of Radiation Exposure Associated With Intraoperative Cone-Beam Computed Tomography and Follow-up Multidetector Computed Tomography Angiography for Evaluating Endovascular Aneurysm Repairs

Purpose: To compare the radiation exposure associated with intraoperative contrast-enhanced cone-beam computed tomography (ceCBCT) acquisitions to standard 3-phase multidetector computed tomography (MDCT) angiography used for assessing technical success after endovascular aortic repair (EVAR). Methods: Effective doses (EDs) were calculated for 66 EVAR patients (mean age 71 years; 61 men) with a mean 27.7-kg/m2 body mass index (range 17–49) who had both intraoperative ceCBCT and postoperative 3-phase MDCT angiography between November 2012 and April 2015. In addition, EDs were directly determined using thermoluminescent dosimeters (TLDs) embedded in anthropomorphic phantoms with body mass indexes of 22 and 30 kg/m2. Effective doses were calculated by summing doses recorded by all TLDs corresponding to a specific tissue type before applying the International Commission on Radiological Protection (ICRP) 60 and 103 weighting factors. EDs were compared with each other for both imaging modalities as well as to TLD measurements. Results: Average EDs of the patient collective were 4.9±1.1 mSv for ceCBCT, 2.6±1.2 mSv for single-phase MDCT (46% decrease, covering solely the area of the implanted endograft), and 13.6±5.5 mSv for comprehensive 3-phase MDCT examinations (178% increase, anatomical coverage from the aortic arch to femoral artery bifurcation). EDs determined in phantom measurements ranged from 3.1 to 4.5 mSv for ceCBCT, amounting to 2.6 mSv for a single MDCT phase (15% to 40% decrease) using ICRP 60 conversion factors. Applying ICRP 103 factors resulted in higher values for ceCBCT and slightly lower ones for MDCT. Conclusion: ceCBCT offers the chance for immediate intraoperative revisions of endograft-related problems. Requiring only a single-phase acquisition, ceCBCT is associated with a considerable reduction in ED (50%–75%) compared to standard 3-phase MDCT angiography after EVAR. On the other hand, MDCT has a larger field of view and is associated with less radiation exposure for a single phase (reduction of 20%–60%) if only the stented region is covered; however, MDCT angiography also uses larger amounts of contrast.

Intraoperative contrast-enhanced cone beam computed tomography to assess technical success during endovascular aneurysm repair

BACKGROUND

The aim of the study was to analyze the use of contrast-enhanced cone beam computed tomography (ceCBCT) during endovascular aneurysm repair (EVAR) and to compare this imaging modality with standard completion digital subtraction angiography (cDSA) and postoperative computed tomography angiography (CTA) regarding the detection of endograft-associated complications.

METHODS

Between September 2012 and April 2015, ceCBCT was used in 98 EVAR patients in addition to cDSA and CTA. Endoleaks, intraluminal thrombus and limb stenoses, contrast agent use, and radiation exposure were recorded for all modalities.

RESULTS

cDSA detected 16 (16.3%) endoleaks; ceCBCT, 35 (35.7%) endoleaks; and CTA, 22 (22.4%) endoleaks. All endoleaks identified by cDSA or CTA were also seen on ceCBCT. ceCBCT detected intraluminal thrombus in three patients (none in cDSA or CTA) and previously undetected limb stenoses in three patients. It prompted intraoperative interventions in 7 of 98 patients (7.1%). Replacing cDSA and CTA by ceCBCT would have caused a 39% reduction of in-hospital contrast agent volume in this cohort.

CONCLUSIONS

ceCBCT can reliably detect all endograft-associated complications during EVAR. It offers the chance for immediate revision of remediable problems in a relevant proportion of patients and could thus reduce early reintervention rates. ceCBCT can safely replace early follow-up CTA and thereby reduce in-hospital use of contrast media.

Endovascular Treatment of Inflammatory Infrarenal Aortic Aneurysms

Objectives:

The aim of this study was to evaluate short- and midterm outcomes of endovascular aneurysm repair in patients with inflammatory abdominal aortic aneurysm (IAAA) focusing on changes in perianeurysmal inflammation and hydronephrosis.

Methods:

A retrospective study was performed considering data prospectively gathered from 1998 to 2013 in 3 centers. Patient demographics, preoperative clinical characteristics, clinical presentation, preoperative imaging measurements, procedural, and postoperative data were collected. Main outcome was to define evolution of periaortic fibrosis and hydronephrosis at computed tomography angiography (CTA) during follow-up.

Results:

A total of 22 patients (male n = 20; mean age 70.9 years ± 9.3) were included (mean AAA diameter: 58 mm ± 11, symptomatic: 50%, ruptured: 9.1%). Hydroureteronephrosis was preoperatively diagnosed by CTA in 6 (27.3%) cases. Median clinical follow-up was 2.2 years (range 0.1-14.5). Nine patients died during follow-up. At 1, 2, 4, and 6 years, overall survival was 85.4%, 74.3%, 56.6%, and 49.5%, respectively. Among these 13 patients with CTA follow-up, the mean AAA diameter was 56.2 mm ± 15.5, and progression of sac diameter was detected in 1 (7.7%) patient. Median maximum thickness of perianeurysmal inflammation was 5 mm (range 2-11) and decreased/remained unchanged in 92.3% of patients. Regression of hydroureteronephrosis occurred in 3 of 5 patients available for follow-up. There were no cases of de novo hydroureteronephrosis.

Conclusion:

Endovascular treatment of IAAA has comparable short-term outcomes with non-IAAA. During midterm follow-up, aneurysm sac progression is rare, and perianeurysmal fibrosis decreases or remains unchanged in most cases. Hydronephrosis regression can occur in some but not all instances and thus warrants close surveillance.

Feasibility and accuracy of fusion imaging during thoracic endovascular aortic repair

OBJECTIVE

To evaluate accuracy and feasibility of fusion imaging during thoracic endovascular aortic repair (TEVAR).

METHODS

From January 2013 to January 2015 fusion imaging was used in 18 TEVAR procedures. Patients were prospectively enrolled for the survey and informed consent was obtained. Planning of the procedure and computed tomography (CT) angiography (CTA) segmentation with determination of all relevant surgical landmarks that should be displayed on fusion imaging was done using the preoperative CTA data. The registration was done with an intraoperative noncontrast-enhanced cone beam CT and CTA (three-dimensional [3D]-3D registration; n = 15) or with two fluoroscopic images in anteroposterior and lateral projection and the CTA (two-dimensional-3D registration; n = 3). An intraoperative digital subtraction angiography was performed to adjust fusion imaging and to allow accuracy measurement.

RESULTS

Fusion imaging was possible in all included patients. The median dose for noncontrast-enhanced cone beam CT imaging was 28.6 Gy/cm(2) (range, 17.9-43.3) and 0.46 Gy cm(2) for two fluoroscopic images in the two-dimensional-3D group. Full accuracy was achieved in two cases (11%), with a median deviation of 11.7 mm (range, 0.0-37.2). Manual realignment was possible in all cases.

CONCLUSIONS

This early experience shows that fusion imaging is feasible in TEVAR procedures using different registration methods. However, it shows a significant deviation in thoracic procedures because of different sources of error, making confirmation of fusion overlay with a digital subtraction angiography necessary in any case.

Finite element analysis in asymptomatic, symptomatic, and ruptured abdominal aortic aneurysms: in search of new rupture risk predictors

OBJECTIVES

To compare biomechanical rupture risk parameters of asymptomatic, symptomatic and ruptured abdominal aortic aneurysms (AAA) using finite element analysis (FEA).

STUDY DESIGN

Retrospective biomechanical single center analysis of asymptomatic, symptomatic, and ruptured AAAs. Comparison of biomechanical parameters from FEA.

MATERIALS AND METHODS

From 2011 to 2013 computed tomography angiography (CTA) data from 30 asymptomatic, 15 symptomatic, and 15 ruptured AAAs were collected consecutively. FEA was performed according to the successive steps of AAA vessel reconstruction, segmentation and finite element computation. Biomechanical parameters Peak Wall Rupture Risk Index (PWRI), Peak Wall Stress (PWS), and Rupture Risk Equivalent Diameter (RRED) were compared among the three subgroups.

RESULTS

PWRI differentiated between asymptomatic and symptomatic AAAs (p < .0004) better than PWS (p < .1453). PWRI-dependent RRED was higher in the symptomatic subgroup compared with the asymptomatic subgroup (p < .0004). Maximum AAA external diameters were comparable between the two groups (p < .1355). Ruptured AAAs showed the highest values for external diameter, total intraluminal thrombus volume, PWS, RRED, and PWRI compared with asymptomatic and symptomatic AAAs. In contrast with symptomatic and ruptured AAAs, none of the asymptomatic patients had a PWRI value >1.0. This threshold value might identify patients at imminent risk of rupture.

CONCLUSIONS

From different FEA derived parameters, PWRI distinguishes most precisely between asymptomatic and symptomatic AAAs. If elevated, this value may represent a negative prognostic factor for asymptomatic AAAs.