Borek Foldyna

Dynamic CT Angiography after Abdominal Aortic Endovascular Aneurysm Repair: Influence of Enhancement Patterns and Optimal Bolus Timing on Endoleak Detection

PURPOSE To determine the time course of enhancement patterns in the aorta and endoleaks at dynamic computed tomographic (CT) angiography as well as their effect on the endoleak detection rate in patients who have undergone abdominal aortic endovascular aneurysm repair (EVAR). MATERIALS AND METHODS This retrospective study was approved by the local ethics committee and compliant with the Declaration of Helsinki. All patients gave written informed consent for the scientific analysis of their data. Seventy-one patients (mean age, 72 years ± 8 [standard deviation]) were retrospectively included after EVAR of the abdominal aorta. All patients underwent dynamic CT angiography with 10 unidirectional scan phases, followed by a venous phase. Endoleaks were detected visually in all scan phases; the magnitude of enhancement was assessed by using region-of-interest measurements in the aorta and the detectable endoleaks. Statistical analysis was performed with the χ(2) test, the paired t test, and analysis of variance with repeated measurements. RESULTS The highest mean aortic enhancement was achieved 12 seconds after the bolus-tracking threshold, and the highest mean endoleak enhancement was achieved 22 seconds after the bolus-tracking threshold. In total, 44 endoleaks were detected. The detection rates differed significantly in between the dynamic CT angiography phases (minimum, seven endoleaks at 2 seconds after the bolus-tracking threshold; maximum, 44 endoleaks at 27 seconds after the bolus-tracking threshold; P = .001). The highest detection rate was achieved when the contrast between aortic and endoleak enhancement reached its maximum. CONCLUSION Dynamic CT angiography revealed that the peak enhancement of endoleaks is significantly different than that of the aorta and that endoleaks may not be adequately evaluated with conventional biphasic CT protocols. The use of dynamic CT angiography is associated with a significantly increased detection rate of endoleaks compared with the detection rates at the time points of conventional biphasic CT.

Real-time magnetic resonance-guided ablation of typical right atrial flutter using a combination of active catheter tracking and passive catheter visualization in man: initial results from a consecutive patient series

AIMS Recently cardiac magnetic resonance (CMR) imaging has been found feasible for the visualization of the underlying substrate for cardiac arrhythmias as well as for the visualization of cardiac catheters for diagnostic and ablation procedures. Real-time CMR-guided cavotricuspid isthmus ablation was performed in a series of six patients using a combination of active catheter tracking and catheter visualization using real-time MR imaging. METHODS AND RESULTS Cardiac magnetic resonance utilizing a 1.5 T system was performed in patients under deep propofol sedation. A three-dimensional-whole-heart sequence with navigator technique and a fast automated segmentation algorithm was used for online segmentation of all cardiac chambers, which were thereafter displayed on a dedicated image guidance platform. In three out of six patients complete isthmus block could be achieved in the MR scanner, two of these patients did not need any additional fluoroscopy. In the first patient technical issues called for a completion of the procedure in a conventional laboratory, in another two patients the isthmus was partially blocked by magnetic resonance imaging (MRI)-guided ablation. The mean procedural time for the MR procedure was 109 ± 58 min. The intubation of the CS was performed within a mean time of 2.75 ± 2.21 min. Total fluoroscopy time for completion of the isthmus block ranged from 0 to 7.5 min. CONCLUSION The combination of active catheter tracking and passive real-time visualization in CMR-guided electrophysiologic (EP) studies using advanced interventional hardware and software was safe and enabled efficient navigation, mapping, and ablation. These cases demonstrate significant progress in the development of MR-guided EP procedures.

Role of Preprocedural Computed Tomography in Transcatheter Aortic Valve Implantation

UNLABELLED Transcatheter aortic valve implantation (TAVI) is currently considered an acceptable alternative for the treatment of patients with severe aortic stenosis and a high perioperative risk or a contraindication for open surgery. The benefit of TAVI significantly outweighs the risk of the procedure in patients requiring treatment that are not suitable for open surgery, and leads to a lower mortality in the one-year follow-up. The absence of a direct view of the aortic root and valve remains a challenge for the transcatheter approach. While direct inspection of the aortic valve during open surgery allows an adequate prosthesis choice, it is crucial for TAVI to know the individual anatomical details prior to the procedure in order to assure adequate planning of the procedure and proper prosthesis choice and patient selection. Among the imaging modalities available for the evaluation of patients prior to TAVI, computed tomography (CT) plays a central role in patient selection. CT reliably visualizes the dimensions of the aortic root and allows a proper choice of the prosthesis size. The morphology of the access path and relevant comorbidities can be assessed. The present review summarizes the current state of knowledge regarding the value of CT in the evaluation of patients prior to TAVI. KEY POINTS CT plays a central role in patient selection and planning prior to TAVI. ▶ CT reliably detects the dimensions of the aortic root including the size of the aortic annulus, the degree of valve calcification and the morphology of the access routes. ▶ CT provides a more accurate measurement of the aortic annulus than 2D TEE and CT is the only imaging modality that allows a risk assessment for paravalvular leakages based on the calcification of the aortic valve.

Application of a Novel CD206+ Macrophage-Specific Arterial Imaging Strategy in HIV-Infected Individuals

Background The ability to noninvasively assess arterial CD206+ macrophages may lead to improved understanding of human immunodeficiency virus (HIV)-associated cardiovascular disease. Methods We trialed a novel macrophage-specific arterial imaging technique. Results We demonstrated colocalization between technetium Tc 99m tilmanocept (99mTc-tilmanocept) and CD206+ macrophages ex vivo. In vivo application of 99mTc-tilmanocept single-photon emission computed tomography/computed tomography revealed high-level 99mTc-tilmanocept uptake across 20.4% of the aortic surface volume among HIV-infected subjects, compared with 4.3% among non-HIV-infected subjects (P = .009). Among all subjects, aortic high-level 99mTc-tilmanocept uptake was related to noncalcified aortic plaque volume (r = 0.87; P = .003) on computed tomographic angiography, and this relationship held when we controlled for HIV status. Conclusion These first-in-human data introduce a novel macrophage-specific arterial imaging technique in HIV. Clinical Trials Registration NCT02542371.

Dynamic CT Angiography after Abdominal Aortic Endovascular Aneurysm Repair: Differences in Contrast Agent Dynamics in the Aorta and Endoleaks—Preliminary Results

PURPOSE To assess differences in aortic and endoleak enhancement in patients after endovascular aneurysm repair (EVAR) with dynamic computed tomography (CT) angiography. MATERIALS AND METHODS Twenty-one consecutive patients (mean age, 74.5 y ± 6; range, 61-88 y) with endoleaks after EVAR of the abdominal aorta were examined on a second-generation dual-source CT unit with 10 unidirectional scan phases (temporal resolution, 5 s; 80 kV; 120 reference-mAs; z-axis field of view, 283 mm), followed by a venous scan phase. Enhancement was assessed in aorta and endoleaks for all phases by density measurements. The diagnostic reliability of endoleak detection was assessed on a five-point confidence scale. RESULTS In total, 26 endoleaks (type I, n = 1; type II, n = 25) were detected. The highest detection rate was found in phase 5 (22 s after threshold; P < .01 vs other dynamic phases). Mean peak aortic enhancement (560 HU ± 96) was present in an early arterial phase (phase 3, 12 s after threshold), whereas the mean peak endoleak enhancement (398 HU ± 174) for type II endoleaks was present later, in phase 4 (17 s after threshold). Despite perceived high diagnostic confidence in phases 1 and 2 (ie, typical arterial phase of biphasic CT protocol), only 23% and 62% of endoleaks were detected, respectively, whereas peak diagnostic confidence (phases 4 and 5) corresponded well with the maximum endoleak detection rate but decreased significantly in later phases (ie, 6-10). CONCLUSIONS Preliminary dynamic CT angiography results in post-EVAR follow-up revealed notably different peaks of endoleak and aortic enhancement, which are not covered sufficiently by conventional biphasic CT protocols. Phase 5 demonstrated the highest type II endoleak detection rate, with high diagnostic confidence.

Diagnostic performance of prospectively ECG triggered versus retrospectively ECG gated 64-slice computed tomography coronary angiography in a heterogeneous patient population.

OBJECTIVE To compare diagnostic performance and applicability of prospectively versus retrospectively gated 64-slice computed tomography coronary angiography (pro-CTCA vs. retro-CTCA) in a heterogeneous patient population compared to invasive coronary angiography. METHODS 77 patients referred to an ECG-gated-CT of the chest were retrospectively included. Pro-CTCA was applied, whenever possible, alternatively retro-CTCA was performed. All coronary artery segments≥1.5 mm were analysed and image quality was assessed. RESULTS In 39 patients retro-CTCA and in 38 patients pro-CTCA was applied, mean heart rate (HR) was 69.5±9.1 min(-1) and 62.8±5.9, respectively. For a stenosis≥50% segment-based (patient-based) analysis revealed a sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of 97%, 98%, 71%, 100% (91%, 82%, 67%, 96%) using retro-CTCA and 94%, 97%, 75%, 99% (93%, 96%, 93%, 96%) using pro-CTCA. Sensitivity and NPV increased in the pro-CTCA group in patients with a HR<65. Vessel-based analysis showed lower diagnostic performance for the right coronary artery (RCA) using pro-CTCA, which increased when HR<65. Image quality did not differ significantly in both groups. CONCLUSIONS Prospectively triggered CTCA in a heterogeneous patient group has a very high diagnostic accuracy and image quality, when used in HR≤65. A low HR is of special importance for the evaluation of the RCA.

Computed tomography-based fat and muscle characteristics are associated with mortality after transcatheter aortic valve replacement

BACKGROUND Computed tomography (CT)-based fat and muscle measures are associated with outcome in large populations. We tested if muscle and fat characteristics are associated with long-term outcomes after TAVR. METHODS We included 403 clinical CTs performed prior to TAVR at our center between 2008 and 2016, measuring area (cm2) and density (Hounsfield units, HU) of both psoas muscles (PM), subcutaneous adipose (SAT), and visceral adipose tissue (VAT). Area measures were indexed to height, log-transformed and both area and density were standardized for analysis. We assessed the association of each measure with all-cause mortality (adjusted for age, sex, body mass index (BMI), and the Society of Thoracic Surgeons (STS) risk score. RESULTS Of the 403 individuals (83 ± 8 years; 52% female), 167 (41.4%) died during a median follow-up of 458 days (interquartile range IQR 297-840). Fat measures were feasible and rapid. Fat area was available in 242 (60%) patients with an adequate field of view. Individuals with the lowest PM area, SAT area or VAT area exhibited the highest hazard of mortality. In addition, greater SAT density was associated with a higher mortality hazard (adjusted HR per standard deviation increase in density = 1.35, 95%CI 1.10-1.67, P = 0.005). CONCLUSION Rapid CT-based tissue characterization is feasible in patients referred for TAVR. Decreased PM area and increased SAT density are associated with long-term mortality after TAVR, even after accounting for age, sex, BMI, and STS score. Further studies are necessary to interrogate sex-specific relationships between CT tissue metrics and mortality and whether CT measures are incremental to well-established frailty metrics.

Access Path Angle in Transapical Aortic Valve Replacement: Risk Factor for Paravalvular Leakage

BACKGROUND The aim of this study was to analyze the angle between the left ventricular (LV) long axis and the LV outflow tract (αLV-LVOT) on cardiac computed tomography and to describe its effect on the occurrence of paravalvular leakage (PL), fluoroscopy time, and postoperative creatine kinase-MB levels in transapical transcatheter aortic valve replacement (TA-TAVR). METHODS High-risk patients with severe aortic stenosis scheduled for TA-TAVR using an Edwards SAPIEN (Edwards Lifesciences, Irvine, CA) prosthesis were retrospectively included. The αLV-LVOT was measured during systole and diastole as far as retrospectively gated data sets were available. The αLV-LVOT was correlated with the occurrence of PL, total fluoroscopy time, and postoperative creatine kinase-MB levels. Interobserver variability was assessed in all cases. RESULTS The study included 81 patients (57 women [70.4%], 24 men [29.6%]) with an average age of 81.9±5.8 years. The mean αLV-LVOTs were 61.8±9.9 degrees during systole and 61.1±10.0 degrees during diastole. There was a minimal, nonsignificant change in the αLV-LVOT between systole and diastole of 0.2±4.1 degrees (p=0.7). PL was found in 39 patients: grade 0 in 42 (51.9%), grade I in 30 (37.0%), and grade II in 9 (11.1%). Patients with a clinically significant PL (grade≥II) showed a significantly greater mean αLV-LVOT than patients with grade I or without PL (mean difference, 13.8±3.2 degrees; p<0.001). No significant correlation was found between the αLV-LVOT and total fluoroscopy time (r=-0.17, p=0.16) and postoperative creatine kinase-MB levels (r=-0.1, p=0.44). CONCLUSIONS During TA-TAVR, greater αLV-LVOTs were associated with significantly higher grades of PL. Thus, the αLV-LVOT might influence the selection of the transapical implantation path and could have a significant effect on designs for future stents or novel delivery devices.

Impact of heart rate and rhythm on radiation exposure in prospectively ECG triggered computed tomography

PURPOSE To evaluate the influence of different heart rates and arrhythmias on scanner performance, image acquisition and applied radiation exposure in prospectively ECG triggered computed tomography (pCT). MATERIALS AND METHODS An ECG simulator (EKG Phantom 320, Müller & Sebastiani Elektronik GmbH, Munich, Germany) was used to generate different heart rhythms and arrhythmias: sinus rhythm (SR) at 45, 60, 75, 90 and 120/min, supraventricular arrhythmias (e.g. sinus arrhythmia, atrial fibrillation) and ventricular arrhythmias (e.g. ventricular extrasystoles), pacemaker-ECGs, ST-changes and technical artifacts. The analysis of the image acquisition process was performed on a 64-row multidetector CT (Brilliance, Philips Medical Systems, Cleveland, USA). A prospectively triggered scan protocol as used for routine was applied (120 kV; 150 mAs; 0.4s rotation and exposure time per scan; image acquisition predominantly in end-diastole at 75% R-R-interval, in arrythmias with a mean heart rate above 80/min in systole at 45% of the R-R-interval; FOV 25 cm). The mean dose length product (DLP) and its percentage increase from baseline (SR at 60/min) were determined. RESULT Radiation exposure can increase significantly when the heart rhythm deviates from sinus rhythm. ECG-changes leading to a significant DLP increase (p<0.05) were bifocal pacemaker (61%), pacemaker dysfunction (22%), SVES (20%), ventricular salvo (20%), and atrial fibrillation (14%). Significantly (p<0.05) prolonged scan time (>8 s) could be observed in bifocal pacemaker (12.8 s), pacemaker dysfunction (10.7 s), atrial fibrillation (10.3 s) and sinus arrhythmia (9.3 s). CONCLUSION In prospectively ECG triggered CT, heart rate and rhythm can provoke different types of scanner performance, which can significantly alter radiation exposure and scan time. These results might have an important implication for indication, informed consent and contrast agent injection protocols.

Analysis of circumflex artery anatomy by real time 3D transesophageal echocardiography compared to cardiac computed tomography

Iatrogenic injury to the circumflex artery (Cx) due to its close proximity to the mitral annulus is a rare but dreadful complication that can occur during mitral valve repair. The aim of our study was to compare multiple measurements of the Cx datasets, obtained by real time three-dimensional transesophageal echocardiography (RT3D TEE) and corresponding measurements assessed in multi-planar three-dimensional images acquired by multidetector computed tomography (MDCT). Preoperative RT3D TEE and MDCT datasets of 25 patients who had previously undergone minimally invasive mitral valve surgery were retrospectively analyzed. The vessel diameter and the horizontal as well as vertical distances from the center of the Cx to the mitral valve annulus were measured. Horizontal as well as vertical Cx distances showed a strong correlation between measurements of RT3D TEE and MDCT whereas the measurements of the Cx diameter showed no correlation. Measurements of horizontal and vertical distances of the Cx to the mitral annulus can be performed using RT3D TEE and show good correlation with MDCT-based measurements.