Detection Of Endoleaks Research Articles

New Applications and Indications for Contrast-Enhanced Sonography in Endovascular Aortic Repair

After edovascular repair of infrarenal aortic aneurysms (EVAR) endoleaks may occur necessitating further therapy. Therefore a reliable method for follow-up imaging after EVAR for detection and control of endoleaks is of high importance. Contrast-enhanced sonography (CEUS) does not require the application of nephrotoxid contrast media and does not stress the patient. CEUS is increasingly used and enables a quick, non-invasive follow-up examination for patient after EVAR. In addition, interventions as therapy for endoleaks may be executed using ultrasound. Initial experience with CEUS-guided aortic stenting shows that the amount of contrast media as well as X-ray time may be reduced.

Acute kidney injury predicts mortality after endovascular aortic repair

Acute kidney injury predicts mortality after endovascular aortic repair

Appearance of the Nellix Endovascular Aneurysm Sealing System on Computed Tomography

Purpose: To describe the imaging characteristics of the Nellix Endovascular Aneurysm Sealing (EVAS) System on serial computed tomography (CT) surveillance. Methods: Sixty-eight patients undergoing EVAS were enrolled in a surveillance protocol that included CT scans prior to hospital discharge and at 3, 6, and 9 months postoperatively. Images were analyzed for the presence of gas within the endobag, endoleak, and for maximum radiodensity measured in Hounsfield units (HU) within the uppermost, middle, and lowermost regions of each endobag. Results: Gas was seen within the endobags of all 68 EVAS repairs at the first postoperative CT compared with 2 (5.6%) of 36 undergoing the 3-month scan. The endobags appeared radiodense during initial imaging, and the median (interquartile range) radiodensity of the Nellix polymer decreased from 158.3 HU (149.5; 169.5) at the postoperative CT to 81.0 HU (74.0; 88.0) at 3 months, excluding 3 cases in which contrast pre-fill was utilized. Type I endoleak was seen at the periphery of the aneurysm sac or in the cleft between the endobags, with a substantially different appearance to endoleak after endovascular aneurysm repair. Conclusion: The evolution of CT appearances after EVAS was characteristic and predictable. The device endobags were initially radiodense, which may impact the detection of endoleak within 3 months of EVAS. Endoleaks after EVAS were seen in a different anatomical area to endoleaks after conventional stent-graft repair.

Contrast-enhanced ultrasound (CEUS) versus computed tomography angiography (CTA) in detection of endoleaks in post-EVAR patients. Are delayed type II endoleaks being missed? A systematic review and meta-analysis.

The purpose of this systematic review is to assess the accuracy of contrast-enhanced ultrasound (CEUS) to computed tomography angiography (CTA) for the detection of endoleaks within EVAR surveillance program. A systematic review in Pubmed, Embase and Cochrane database was performed. Articles assessing diagnostic accuracy and comparative modality (CTA vs. CEUS) for endoleaks in adult patients within surveillance programs were retrieved. Methodological assessment was performed, using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tools. The sensitivity and specificity of data were extracted and statistical analysis was performed using MetaDiSc version 1.4. Eight articles were found eligible (n = 454 patients). The pooled sensitivity of CEUS at detecting endoleak is 0.914 (CI 0.866-0.949) and pooled specificity is 0.782 (CI 0.741-0.820). The CEUS with its dynamic nature and longer scanning window demonstrated to be a highly sensitive modality for endoleak detection in comparison to CTA in delayed endoleaks type II.

Ultrasonography: Use of Echo-Doppler in Identification of Endoleaks in Post-Implantation of Thoracic Endovascular Aortic Repair (TEVAR)

Introduction: A thoracic aortic aneurysm (TAA) is a condition with ahigh mortality rate, which is associated with atherosclerosis, age, infection, inflammation, trauma, congenital abnormality or degeneration. The main treatment is conventional Surgery and there is an emerging technique, Thoracic Endovascular Aortic Repair (TEVAR). The latter is a non-invasive procedure, quickly adopted by clinicians for the endovascular treatment of TAA. Purpose: The purpose of this review article is to highlight the advantages andthe appropriateness of the use of Doppler ultrasound in the early detection and follow-up of endoleaks after TEVAR compared with other imaging techniques. Methods: We conducted a review of the literature, based on the keywords: aneurysm, TEVAR, endoleak, follow-up, imaging techniques, Doppler ultrasound. We used PubMed and B-on data, where 48 articles were selected, 27 of these were analyzed because they corresponded to the keywords above. Development: The main complication inherent in TEVAR, is the formation ofendoleaks. Thus, it is extremely important to employ different imaging techniques. Computerized tomography (CT) is the Gold Standard in the detection and identification of endoleaks. Doppler ultrasound has been recognized as a good choice for this technique due to its low cost, easy interpretation and implementation and lack of exposure to any type of radiation. Conclusion: Doppler ultrasound is an imaging technique of high quality andcomparable to CT in the measurement of aneurysm, endoleak after TEVAR identification and can be used for surveillance and follow-up.

Use of three-dimensional contrast-enhanced duplex ultrasound imaging during endovascular aneurysm repair

Iodinated contrast during endovascular aneurysm repair (EVAR) is used with caution in patients with chronic kidney disease. Contrast-enhanced ultrasound (CEUS) imaging using nonnephrotoxic sulphur hexafluoride microbubble contrast is a novel imaging modality that accurately identifies and characterizes endoleaks during EVAR follow-up. We report our initial experience of using three-dimensional (3D) CEUS imaging intraoperatively as completion imaging after endograft deployment. Our aim was to compare intraoperative 3D CEUS against uniplanar angiography in the detection of endoleak, stent deformity, and renal artery perfusion during EVAR. The study enrolled 20 patients undergoing elective conventional infrarenal EVAR, after which a completion angiogram was performed and the presence of endoleak, renal artery perfusion, or device deformity were recorded. With the patient still under anesthetic, a vascular scientist blinded to angiographic findings performed 3D CEUS and reported on the same parameters. Three endoleaks, one type I and two type II, were detected on uniplanar angiography and 13 endoleaks, 11 type II and two type I, were found using 3D CEUS imaging. Of note, one of these type I endoleaks was not seen on angiography, and this patient underwent balloon moulding of the neck with resolution of the endoleak on repeat imaging. Of the 11 type II endoleaks seen with 3D CEUS imaging, the inflow vessel was identified in nine cases. No graft deformity or limb kinking was seen in any patient. Both renal arteries could be visualized in 10 patients, whereas the target renal artery was seen in 11 patients. In the remaining patients, the renal arteries could not be visualized, mainly due to intra-abdominal gas or patient body habitus. 3D CEUS imaging detected endoleaks not seen on uniplanar digital subtraction angiography, including a clinically important type I endoleak, and was also more sensitive than 2D CEUS imaging for the detection of the source of endoleak. This technology has the potential to supplement or replace digital subtraction angiography for completion imaging to reduce the use of x-ray contrast. Intraoperative 3D CEUS has been applied to allow safe EVAR with ultralow or no iodinated contrast usage in selected cases, without compromising completion imaging.

Commentary on: “Could Four Dimensional Contrast-enhanced Ultrasounds Replace Computed Tomography Angiography During Follow-up of Fenestrated Endografts? Results of a Preliminary Experience”

Fenestrated endovascular aneurysm repair (fEVAR) is a wellestablished alternative to open repair for patients with juxtarenal or short-neck AAAs. While computed tomography angiography (CTA) is considered the gold standard for surveillance, it bears the risk of contrast nephropathy and exposure to ionizing radiation, and is associated with high cost and resource allocation. Recommendations for standard EVAR have progressively changed to accept Duplex ultrasound (DUS)-based strategies, at least for patients at lower risk of complications. Currently, there are no specific recommendations from scientific societies regarding fEVAR surveillance, but expert opinion suggests close surveillance is necessary to insure lasting results. Gargiulo et al. addressed the issue of surveillance after fEVAR in a retrospective study comparing CTA and fourdimensional contrast-enhanced ultrasound (4D-CEUS). The authors suggest that 4D-CEUS is as accurate as CTA for detecting diameter and volume changes, endoleaks, and revascularized visceral vessel patency.While the conclusions are interesting, these data must be analyzed with caution. In fact, endoleak detection may be sub-optimal, as one in three endoleaks were not detected with CEUS. A sample of 22 patients is clearly underpowered to obtain conclusions that may influence clinical practice. It may be possible that, due to the relative rarity of fEVAR, one may never obtain enough power for robust conclusions. Also, the added value of 4D (compared to “standard” CEUS) appears only pertinent for volumetric measurements. While this is a valuable research tool, it is not regularly used in clinical practice and may have very limited influence on the course of treatment. As such, the present study does not add significantly to the larger study by Perini et al., where CEUS was compared favorably to CTA. Lastly, DUS and CEUS have important limitations that limit its applicability. These are largely related to access to

Type II endoleaks

Type II endoleaks after endovascular aneurysm repair are the most common type of endoleak and generate the majority of secondary interventions. Their natural history is mostly benign, but they can occasionally lead to sac expansion and eventual rupture. Three-phase computed tomography angiography is the "gold standard" for diagnosis, but duplex ultrasound with or without contrast enhancement and magnetic resonance angiography offer an alternative for endoleak detection or surveillance. Whereas there are concerns as to whether sac expansion can be a dependable marker for risk of rupture, it is currently the best surrogate available and guides the indication for intervention. Obliteration of type II endoleaks can be challenging, and a variety of techniques, endovascular, open, and laparoscopic, have been proposed. The most common approaches are transarterial and translumbar embolization, and they are usually successful, provided the operator is experienced and persistent, targeting both the branches and the nidus of the endoleak. Recurrences and subsequent reinterventions should be anticipated, and on continuing sac expansion, repeated endovascular or open surgical and laparoscopic alternatives may be required.

Carbon dioxide digital subtraction angiography as an option for detection of endoleaks in endovascular abdominal aortic aneurysm repair procedure

The purpose of this study was to evaluate carbon dioxide digital subtraction angiography (CO2-DSA) as an option for the detection of endoleaks (ELs) in the endovascular abdominal aortic aneurysm repair (EVAR) procedure. Forty patients with abdominal aortic aneurysm who were scheduled to undergo EVAR were enrolled in the study. There were 35 men and five women (mean age, 77.9 years). All patients had both iodinated contrast conventional DSA (C-DSA) and CO2-DSA immediately after EVAR. The sensitivity and specificity were calculated for the ability of CO2-DSA to detect ELs. We also correlated with computed tomography findings 6 months after EVAR. C-DSA showed that 27 of the 40 patients (68%) had 28 ELs (type I, four; type II, 20; type III, three; type IV, one). CO2-DSA showed that 16 of the 40 patients (40%) had 17 ELs (type I, four; type II, 10; type III, three; type IV, none). For the prediction of direct ELs (type I and type III) with use of C-DSA as the criterion standard, CO2-DSA has a sensitivity of 1.0 and a specificity of 1.0. For the detection of persistent type II ELs (n = 11) with use of computed tomography findings 6 months from EVAR as the criterion standard, CO2-DSA has a sensitivity of 0.87 and a specificity of 0.97. C-DSA has a sensitivity of 0.82 and a specificity of 0.64. CO2-DSA is reliable for the detection of direct ELs and persistent type II ELs in EVAR. CO2-DSA can be an option to detect ELs in the EVAR procedure.

Duplex Ultrasound versus Computed Tomography for the Postoperative Follow-Up of Endovascular Abdominal Aortic Aneurysm Repair. Where Do We Stand Now?

In the last decade, endovascular aneurysm repair (EVAR) has rapidly developed to be the preferred method for infrarenal abdominal aortic aneurysm repair in patients with suitable anatomy. EVAR offers the advantage of lower perioperative mortality and morbidity but carries the cost of device-related complications such as endoleak, graft migration, graft thrombosis, and structural graft failure. These complications mandate a lifelong surveillance of EVAR patients and their endografts. The purpose of this study is to review and evaluate the safety of color-duplex ultrasound (CDU) as compared with computed tomography (CT), based on the current literature, for post-EVAR surveillance. The post-EVAR follow-up modalities, CDU versus CT, are evaluated questioning three parameters: (1) accuracy of aneurysm size, (2) detection and classification of endoleaks, and (3) detection of stent-graft deformation. Studies comparing CDU with CT scan for investigation of post-EVAR complications have produced mixed results. Further and long-term research is needed to evaluate the efficacy of CDU versus CT, before CDU can be recommended as the primary imaging modality for EVAR surveillance, in place of CT for stable aneurysms.

Could Four-dimensional Contrast-enhanced Ultrasound Replace Computed Tomography Angiography During Follow up of Fenestrated Endografts? Results of a Preliminary Experience

To evaluate four-dimensional contrast-enhanced ultrasound (4D-CEUS) as an alternative imaging method to computed tomography angiography (CTA) during follow up of fenestrated endovascular aneurysm repair (FEVAR) for juxta- and para-renal abdominal aortic aneurysms (AAA). Between October 2011 and March 2012, all consecutive patients who underwent FEVAR follow up were included in the study and evaluated with both 4D-CEUS and CTA. The interval between the two examinations was always ≤ 30 days. Endpoints were the comparison of postoperative AAA diameter, AAA volume, presence of endoleaks, revascularized visceral vessel (RVV) visualization, and patency. Comparative analysis was performed using Bland-Altman plots and McNemar's Chi-square test. Twenty-two patients (96% male, 4% female; mean age 74 ± 7 years; American Society of Anesthesiologists grade III/IV 82%/18%) were enrolled. Seventy-eight RVV (fenestrations: 60; scallops: 17; branches: 1) were analyzed. The mean AAA diameter evaluated by 4D-CEUS and CTA was 45 ± 10 mm (range 30-69 mm) and 48 ± 9 mm (range 32-70 mm), respectively. The mean difference was 3 ± 3 mm. The mean AAA volume evaluated by 4D-CEUS and CTA was 150 ± 7 cc (range 88-300 cc) and 159 ± 68 cc (range 80-310 cc), respectively. The mean difference was 7 ± 4 cc; a Bland-Altman plot revealed agreement in AAA diameter and volume evaluation (p < .01) between 4D-CEUS and CTA. The observed agreement for the detection of endoleaks was 95%. McNemar's Chi-square test confirmed that 4D-CEUS and CTA were equivalent (p > .05) at detecting endoleaks. The first segment of six (8%) RVVs (four renal and two superior mesenteric arteries) was not directly visualized by 4D-CEUS owing to obesity, but the contrast enhancement into the distal part of vessel or into the relative parenchyma gave indirect information about their patency. McNemar's Chi-square test demonstrated the superiority of CTA (p = .031) in visualizing RVVs. The patency of 77/78 RVVs was confirmed with both techniques. McNemar's Chi-square test confirmed that 4D-CEUS and CTA were equivalent in their ability to detect visceral vessel patency. The data suggest that 4D-CEUS is as accurate as CTA in the evaluation of postoperative AAA diameter and volume, endoleak detection, and RVV patency after FEVAR. Four-dimensional CEUS could provide hemodynamic information regarding RVVs, and reduce radiation exposure and renal impairment during follow up. Obesity limits the diagnostic accuracy of 4D-CEUS.

Dual-source dual-energy CT: dose reduction after endovascular abdominal aortic aneurysm repair

This study was done to evaluate the possibility of reducing the dose of ionising radiation by using dual-source dual-energy computed tomography (CT) in patients undergoing CT angiography of the aorta to search for endoleaks after endovascular aneurysm repair (EVAR). One hundred and forty-eight patients (117M, 31F; mean age 75±6.5) underwent 171 CT angiography scans for follow-up after EVAR. For each patient we performed a triple-phase acquisition protocol consisting of a nonenhanced phase, an arterial phase and a delayed phase; the latter acquired in dual energy. Two radiologists jointly evaluated the nonenhanced, arterial and delayed phase, and a third radiologist evaluated only the delayed phase and its virtual noncontrast (VNC) reconstruction. Moreover, we compared the cumulative effective doses of the triple-phase acquisition with the dual-energy acquisition. We detected 34 endoleaks (19.8%), with 100% agreement between the triple-phase and dual-energy acquisitions. The effective dose of dual-energy acquisition performed during the delayed phase was 61.7% lower than that of the triple-phase acquisition. A dual-energy CT scan acquired during the delayed phase and its VNC reconstruction allow detection of endoleaks with a substantial reduction of effective dose and a complete diagnostic agreement with a triple-phase acquisition protocol.

Dual-energy computed tomography after endovascular aortic aneurysm repair: the role of hard plaque imaging for endoleak detection.

To assess the diagnostic accuracy of dual-energy computed tomography (DECT) for detection of endoleaks and aneurysm sac calcifications after endovascular aneurysm repair (EVAR) using hard plaque imaging algorithms. One hundred five patients received 108 triple-phase contrast-enhanced CT (non-contrast, arterial and delayed phase) after EVAR. The delayed phase was acquired in dual-energy and post-processed using the standard (HPI-S) and a modified (HPI-M) hard plaque imaging algorithm. The reference standard was determined using the triple-phase CT and contrast-enhanced ultrasound. All images were analysed separately for the presence of endoleaks and calcifications by two independent readers; sensitivity, specificity and interobserver agreement were calculated. Endoleaks and calcifications were present in 25.9% (28/108) and 20.4% (22/108) of images. The HPI-S images had a sensitivity/specificity of 54%/100% (reader 1) and 57%/99% (reader 2), the HPI-M images of 93%/92% (reader 1) and 96%/92% (reader 2) for detection of endoleaks. For detection of calcifications HPI-S had a sensitivity/specificity of 91%/99% (reader 1) and 95%/97% (reader 2), the HPI-M images of 91%/99% (reader 1) and 91%/99% (reader 2), respectively. Using HPI-M, DECT enables an accurate diagnosis of endoleaks after EVAR and allows distinguishing between endoleaks and calcifications with high diagnostic accuracy. • Dual-energy computed tomography allows the diagnosis of aortic pathologies after EVAR. • Hard plaque imaging algorithms can distinguish between endoleaks and aneurysm sac calcifications. • The modified hard plaque imaging algorithm detects endoleaks with high diagnostic accuracy.

Dynamic Volumetric CT Angiography for the Detection and Classification of Endoleaks: Application of Cine Imaging Using a 320-Row CT Scanner with 16-cm Detectors

PurposeTo assess the feasibility and diagnostic performance of dynamic volumetric computed tomography (CT) angiography with large-area detectors in the detection and classification of endoleaks after endovascular aneurysm repair (EVAR). Materials and MethodsLow-dose dynamic volumetric CT angiography performed with the patient in Fowler position was used to scan the entire stent graft with a 16-cm-area detector during the first follow-up examination after EVAR. There were 39 consecutive patients (36 men and 3 women; mean age, 74 y ± 8.7) examined with approximately 14–20 intermittent scans (temporal resolution, 2 s; scan range, 160 mm). The effective radiation dose, image quality, interobserver and intraobserver agreement for endoleak detection, and time delay between peak enhancement of the aorta and endoleaks were evaluated. ResultsAll examinations with the patient in Fowler position enabled the entire stent graft to be scanned and were rated as diagnostic. The mean effective radiation dose was 13.1 mSv. Endoleaks were detected in eight patients (type Ia, n = 1; type II, n = 6; type III, n = 1). Interobserver agreement (κ = 0.794) and intraobserver agreement (κ = 1.00) for detection of endoleaks were excellent. The mean time delay between peak enhancement of the aorta and the endoleaks was significantly less for type I/III endoleaks (2.0 s ± 0) compared with type II endoleaks (5.3 s ± 1.0; P < .001). ConclusionsLow-dose dynamic volumetric CT angiography performed with the patient in Fowler position is feasible after EVAR. Dynamic information, including cine imaging, the timing of peak enhancement, and the Hounsfield units index, is useful in detecting and classifying endoleaks.

Incidental Detection of an Aortic Stent Endoleak With Contrast‐Enhanced Sonography

Incidental Detection of an Aortic Stent Endoleak With Contrast‐Enhanced Sonography

3D Contrast Enhanced Ultrasound for Detecting Endoleak Following Endovascular Aneurysm Repair (EVAR)

CT angiography (CTA) for endovascular aneurysm repair (EVAR) surveillance involves irradiation and nephrotoxic X-ray contrast agents. Three-dimensional contrast enhanced ultrasound (3D CEUS) is a novel imaging technique that may be more sensitive to blood flow detection than CTA or 2D CEUS. 3D CEUS utilises positional information from magnetic field emitters to assemble all ultrasound reflections into a high-definition image. We compared 3D CEUS with CTA for the detection of endoleak and aneurysm expansion following EVAR. 3D CEUS (Curefab), 2D CEUS (Philips IU22), and CTA were compared in 30-paired images from 23 patients. Sensitivity, specificity, positive, and negative predictive value were calculated for 2D and 3D CEUS against CTA as the 'gold standard'. Pearson correlation was used to compare aneurysm sac diameter. Data were analysed using SPSS version 19.0. 30 paired 3D CEUS and CTA images were analysed from 23 patients. Endoleaks were detected in 17 images with CTA, 18 on 2D CEUS, and 18 on 3D CEUS. The sensitivity, specificity, positive, and negative predictive values of 3D CEUS to detect endoleak were 100%, 92%, 94%, and 100%, respectively. There was excellent correlation (r=0.935; p≤.0001) between CTA and 3D CEUS for AAA sac diameter. Only 3D CEUS detected the inflow and outflow arteries in all 18 scans with endoleak. 2D CEUS detected the inflow in 16 (88.8%) and CTA on 12 (66.6%) of the images. 3D CEUS may be more sensitive to endoleak following EVAR than either 2D CEUS or CTA.

Evaluation of Low-Dose CT Angiography With Model-Based Iterative Reconstruction After Endovascular Aneurysm Repair of a Thoracic or Abdominal Aortic Aneurysm

The objective of our study was to evaluate image quality and overall adequacy of low-dose CT angiography (CTA) with model-based iterative reconstruction (MBIR) in patients who had undergone endovascular aneurysm repair (EVAR) of a thoracic or abdominal aortic aneurysm. Thirty patients, all of whom had undergone standard-dose CTA performed previously with adaptive statistical iterative reconstruction (ASIR), underwent low-dose CTA for surveillance after EVAR. Two radiologists randomly evaluated both studies, and quality parameters were assessed. The maximal aneurysm diameter was measured, and the images were evaluated to see whether an endoleak was present. The image noise and contrast-to-noise ratio (CNR) were measured. The volume CT dose index and dose-length product were recorded. The mean image score for low-dose CTA was acceptable to very good in all categories of assessment. There was no significant difference between low-dose CTA and standard-dose CTA in the evaluation of the stent lumen. Subjective assessments of stent configuration, aneurysm outline, aortic branch vessel outline, overall adequacy of vascular imaging, and overall adequacy of solid organ imaging were superior on standard-dose CTA. Interobserver agreement for endoleak detection was higher for low-dose CTA. There was no significant difference in the mean aneurysm diameter between the two readers on low-dose CTA and standard-dose CTA. The effective radiation dose for low-dose CTA was lower than standard-dose CTA during both the arterial (mean, 4.4 vs 16.2 mSv, respectively) and the delayed (2.4 vs 6.7 mSv) phase acquisitions. The measured image noise was lower (14.7 vs 19.3 HU) and CNR was higher (25.6 vs 17.1) on the low-dose CTA studies than on the standard-dose CTA studies. Low-dose CTA with MBIR enables up to 73% dose reduction as compared with CTA performed with ASIR while maintaining diagnostic adequacy for CTA surveillance of patients who have undergone EVAR of a thoracic or abdominal aortic aneurysm.

Imaging Follow-up of Endovascular Repair of Type B Aortic Dissection with Dual-Source, Dual-Energy CT and Late Delayed-Phase Scans

PurposeTo evaluate the diagnostic performance of dual-energy (DE) computed tomography (CT) after thoracic endovascular aortic repair (TEVAR) of type B dissection, and to investigate the value of late delayed (LD) acquisition in endoleak detection and false lumen patency assessment. Materials and MethodsTwenty-four patients with TEVAR for type B dissection underwent 53 tripe-phase CT examinations. Single-source unenhanced acquisition was followed by single-source arterial-phase and DE LD phase (300-s delay) imaging. Virtual noncontrast images were generated from DE acquisition. Two blinded radiologists retrospectively evaluated the cases in three reading sessions: session A (triphasic protocol), session B (virtual noncontrast and arterial phase), and session C (virtual noncontrast and arterial and LD phases). Endoleak detection accuracy during sessions B and C compared with session A (reference standard) was investigated. False lumen patency was assessed. Effective radiation dose was calculated. ResultsSession A revealed 37 endoleaks in 30 of 53 studies (56.6%). Session B revealed 31 of the 37 endoleaks, with one false-positive case, 83.8% sensitivity, 95.8% specificity, 79.3% negative predictive value, and 96.9% positive predictive value. Session C correctly depicted all 37 endoleaks, with one false-positive case, 100% sensitivity, 95.8% specificity, 100% negative predictive value, and 97.4% positive predictive value. Underestimation of false lumen patency was found in session B (P = .013). Virtual noncontrast imaging resulted in 17% radiation exposure reduction. ConclusionsVirtual noncontrast imaging can replace standard unenhanced images in follow-up after TEVAR of type B dissection, thus reducing radiation dose. Delayed-phase imaging is valuable in low-flow endoleaks detection and false lumen patency assessment.

Endoleak and In-Stent Thrombus Detection with CT Angiography in a Thoracic Aortic Aneurysm Phantom at Different Tube Energies Using Filtered Back Projection and Iterative Algorithms

To determine the lower limit of dose reduction with hybrid and fully iterative reconstruction algorithms in detection of endoleaks and in-stent thrombus of thoracic aorta with computed tomographic (CT) angiography by applying protocols with different tube energies and automated tube current modulation. The calcification insert of an anthropomorphic cardiac phantom was replaced with an aortic aneurysm model containing a stent, simulated endoleaks, and an intraluminal thrombus. CT was performed at tube energies of 120, 100, and 80 kVp with incrementally increasing noise indexes (NIs) of 16, 25, 34, 43, 52, 61, and 70 and a 2.5-mm section thickness. NI directly controls radiation exposure; a higher NI allows for greater image noise and decreases radiation. Images were reconstructed with filtered back projection (FBP) and hybrid and fully iterative algorithms. Five radiologists independently analyzed lesion conspicuity to assess sensitivity and specificity. Mean attenuation (in Hounsfield units) and standard deviation were measured in the aorta to calculate signal-to-noise ratio (SNR). Attenuation and SNR of different protocols and algorithms were analyzed with analysis of variance or Welch test depending on data distribution. Both sensitivity and specificity were 100% for simulated lesions on images with 2.5-mm section thickness and an NI of 25 (3.45 mGy), 34 (1.83 mGy), or 43 (1.16 mGy) at 120 kVp; an NI of 34 (1.98 mGy), 43 (1.23 mGy), or 61 (0.61 mGy) at 100 kVp; and an NI of 43 (1.46 mGy) or 70 (0.54 mGy) at 80 kVp. SNR values showed similar results. With the fully iterative algorithm, mean attenuation of the aorta decreased significantly in reduced-dose protocols in comparison with control protocols at 100 kVp (311 HU at 16 NI vs 290 HU at 70 NI, P ≤ .0011) and 80 kVp (400 HU at 16 NI vs 369 HU at 70 NI, P ≤ .0007). Endoleaks and in-stent thrombus of thoracic aorta were detectable to 1.46 mGy (80 kVp) with FBP, 1.23 mGy (100 kVp) with the hybrid algorithm, and 0.54 mGy (80 kVp) with the fully iterative algorithm.

Value of high-resolution contrast-enhanced ultrasound in detection and characterisation of endoleaks after EVAR.

To compare the value of high-resolution contrast-enhanced ultrasound in the detection and characterisation of endoleaks after EVAR. In this retrospective study, a cohort of 80 patients underwent both standard examination using a curved array 5 MHz transducer and a second examination using a curved array 9 MHz transducer. The examination included B-mode, color Doppler and contrast-enhanced ultrasound using the Philips EPIQ 7 scanner. 80 patients were included in the study. CEUS was used as the preferred examination in determining the presence of an endoleak. The sensitivity and specificity for the detection of endoleak using the 5 MHz transducer was: CEUS (96.8%, 100%), Color Doppler (47.6%, 94.1%), B-mode (15.8%, 94.1%), while for the 9 MHz transducer: CEUS (100%, 100%), Color Doppler (39.7%, 94.1%), B-mode (23.8%, 24.1%). High resolution ultrasound (9 MHz) in detection and characterization of endoleaks after EVAR has some minor advantages in comparison to lower resolution ultrasound (5 MHz).