Cameron J. Hague

3-dimensional aortic annular assessment by multidetector computed tomography predicts moderate or severe paravalvular regurgitation after transcatheter aortic valve replacement: a multicenter retrospective analysis.

OBJECTIVES This study sought to analyze multidetector computed tomography (MDCT) 3-dimensional aortic annular dimensions for the prediction of paravalvular aortic regurgitation (PAR) following transcatheter aortic valve replacement (TAVR). BACKGROUND Moderate or severe PAR after TAVR is associated with increased morbidity and mortality. METHODS A total of 109 consecutive patients underwent MDCT pre-TAVR with a balloon expandable aortic valve. Differences between transcatheter heart valve (THV) size and MDCT measures of annular size (mean diameter, area, and circumference) were analyzed concerning prediction of PAR. Patients with THV malposition (n = 7) were excluded. In 50 patients, MDCT was repeated after TAVR to assess THV eccentricity (1 - short diameter/long diameter) and expansion (MDCT measured THV area/nominal THV area). RESULTS Moderate or severe PAR (13 of 102) was associated with THV undersizing (THV diameter - mean diameter = -0.7 ± 1.4 mm vs. 0.9 ± 1.8 mm for trivial to mild PAR, p < 0.01). The difference between THV size and MDCT annular size was predictive of PAR (mean diameter: area under the curve [AUC]: 0.81, 95% confidence interval [CI]: 0.68 to 0.88; area: AUC: 0.80, 95% CI: 0.65 to 0.90; circumference: AUC: 0.76, 95% CI: 0.59 to 0.91). Annular eccentricity was not associated with PAR (AUC: 0.58, 95% CI: 0.46 to 0.75). We found that 35.3% (36 of 102) and 45.1% (46 of 102) of THVs were undersized relative to the MDCT mean diameter and area, respectively. THV oversizing relative to the annular area was not associated with THV eccentricity or underexpansion (oversized vs. undersized THVs; expansion: 102.7 ± 5.3% vs. 106.1 ± 5.6%, p = 0.03; eccentricity: median: 1.7% [interquartile range: 1.4% to 3.0%] vs. 1.7% [interquartile range: 1.1% to 2.7%], p = 0.28). CONCLUSIONS MDCT-derived 3-dimensional aortic annular measurements are predictive of moderate or severe PAR following TAVR. Oversizing of THVs may reduce the risk of moderate or severe PAR.

The Impact of Integration of a Multidetector Computed Tomography Annulus Area Sizing Algorithm on Outcomes of Transcatheter Aortic Valve Replacement A Prospective, Multicenter, Controlled Trial

OBJECTIVES This study prospectively investigated the impact of integration of a multidetector computed tomography (MDCT) annular area sizing algorithm on transcatheter aortic valve replacement (TAVR) outcomes. BACKGROUND Appreciation of the 3-dimensional, noncircular geometry of the aortic annulus is important for transcatheter heart valve (THV) sizing. METHODS Patients being evaluated for TAVR in 4 centers underwent pre-procedural MDCT. Recommendations for balloon-expandable THV size selection were based on an MDCT sizing algorithm with an optimal goal of modest annulus area oversizing (5% to 10%). Consecutive patients who underwent TAVR with the algorithm (MDCT group) were compared with consecutive patients without the algorithm (control group). The primary endpoint was the incidence of more than mild paravalvular regurgitation (PAR), and the secondary endpoint was the composite of in-hospital death, aortic annulus rupture, and severe PAR. RESULTS Of 266 patients, 133 consecutive patients underwent TAVR (SAPIEN XT THV) in the MDCT group and 133 consecutive patients were in the control group. More than mild PAR was present in 5.3% (7 of 133) of the MDCT group and in 12.8% (17 of 133) in the control group (p = 0.032). The combined secondary endpoint occurred in 3.8% (5 of 133) of the MDCT group and in 11.3% (15 of 133) of the control group (p = 0.02), driven by the difference of severe PAR. CONCLUSIONS The implementation of an MDCT annulus area sizing algorithm for TAVR reduces PAR. Three-dimensional aortic annular assessment and annular area sizing should be considered for TAVR.

Aortic Annulus Diameter Determination by Multidetector Computed Tomography: Reproducibility, Applicability, and Implications for Transcatheter Aortic Valve Implantation

OBJECTIVES This study sought to determine the most reproducible multidetector computed tomography (MDCT) measurements of the aortic annulus and to determine methods to improve the applicability of these measurements for transcatheter aortic valve implantation. BACKGROUND The reproducibility and applicability of MDCT annular measurements to guide transcatheter aortic valve implantation remain unclear. METHODS Annular measurements were performed in 50 patients planed for transcatheter aortic valve implantation in multiple planes: basal ring (short- and long-axis, mean diameter, area-derived diameter), coronal, sagittal, and 3-chamber projections. A theoretical model was developed taking into account the differences between the most reproducible MDCT measurements and transesophageal echocardiography to guide valve size choice. RESULTS The most reproducible measurements were the area-derived diameter and basal ring average diameter (inter-reader intraclass correlation coefficient: 0.87 [95% confidence interval: 0.81 to 0.92] and 0.80 [95% confidence interval: 0.70 to 0.87]; respectively; intrareader >0.90 for all readers). These were generally larger than transesophageal echocardiography diameters (mean difference of 1.5 ± 1.6 mm and 1.1 ± 1.7 mm, respectively). When a strategy of valve-sizing is undertaken using these CT measurements using an echocardiographic sizing scale, a different THV size would be selected in 44% and 40% of cases, respectively. When adjusting the sizing cutoffs to account for the differences in observed diameters, this was reduced to 10% to 12% (p < 0.01 for both, respectively). CONCLUSIONS The most reproducible MDCT measurements of the annulus are the area-derived diameter and basal ring average diameter, with derived values generally larger than those obtained with echocardiography. If MDCT is used for valve sizing, a strategy incorporating these differences may be important. MDCT using these easily derived measurements may be ideally suited to sizing transcatheter aortic valves as they account for the eccentricity of the aortic annulus, are reproducible, and are noninvasive.

Reduced Iodine Load at CT Pulmonary Angiography with Dual-Energy Monochromatic Imaging: Comparison with Standard CT Pulmonary Angiography—A Prospective Randomized Trial

PURPOSE To compare quantitative and subjective image quality and radiation dose between standard computed tomographic (CT) pulmonary angiography (CTPA) and CTPA with a dual-energy technique with reduced iodine load. MATERIALS AND METHODS This prospective study was approved by the institutional review board and each participant provided informed consent. Ninety-four patients (59% male; mean age ± standard deviation, 62 years ± 15) were randomized to one of two protocols: standard CTPA (100-120 kVp) with standard contrast medium injection (n = 46) and dual-energy CTPA (image reconstruction at 50 keV) with the same injection volume as in the standard protocol but composed of contrast medium and saline in a 1:1 fashion, resulting in 50% reduction in iodine load (n = 48). Signal intensity and noise in three central and two segmental pulmonary arteries were measured; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate vascular enhancement and image noise. The proportion of diagnostic (score, ≥ 3) studies and the interreader agreement regarding the dichotomized diagnostic versus nondiagnostic scale were compared between the two groups. RESULTS Compared with standard CTPA, dual-energy CTPA demonstrated higher signal intensity in all pulmonary arteries (all P < .01), inferior noise only in segmental arteries (P < .05), higher SNR and CNR (both P < .05), and compatible effective dose (P > .05). The five-point score was higher in the standard CTPA protocol (P < .05). The interreader agreement regarding the dichotomized diagnostic versus nondiagnostic scale was similar (P > .05) between the two groups. CONCLUSION Dual-energy CTPA with image reconstruction at 50 keV allows a significant reduction in iodine load while improving intravascular signal intensity, maintaining SNR and with comparable radiation dose.

Iterative reconstruction for coronary CT angiography: finding its way

Image reconstruction algorithms play a critical role in defining the quality and integrity of medical imaging using computed tomography. Since the advent of CT, image reconstruction has largely been performed by filtered back projection (FBP). This reconstruction technique has served CT well particularly at a time when there were significant limitations in computer processing capabilities. Iterative image reconstruction algorithms were, in fact available and were used to generate images with the very first commercial clinical computed tomographic (CT) scanner. This technique did not see significant adoption in clinical CT use owing to the ease of implementation and the faster image reconstruction of filtered back projection. Over the past decade, the need for finer resolution, greater volume coverage, faster scan times and the desire to lower radiation dose at the same time have pushed the performance of FBP reconstruction to its limits. Recently, there has been a re-introduction of iterative reconstruction for CT imaging with recently published studies in other organ systems showing that iterative reconstructions can produce higher-resolution images with greater robustness for the reduction of various imaging artifacts. There has been subsequent early adoption and experience with iterative reconstruction in coronary CT angiography (CCTA). We herein review the various iterative reconstruction platforms released for use for CCTA and the initial experiences implementing and integrating these reconstruction algorithms in clinical practice.

Computed tomography-based sizing recommendations for transcatheter aortic valve replacement with balloon-expandable valves: Comparison with transesophageal echocardiography and rationale for implementation in a prospective trial.

BACKGROUND Computed tomography (CT) annular measurements are predictive of paravalvular regurgitation after transcatheter aortic valve replacement (TAVR) which is a predictor of mortality and morbidity. OBJECTIVES To demonstrate the rationale and potential implications of new CT sizing recommendations for TAVR. METHODS The CT sizing recommendations aim to ensure routine transcatheter heart valve (THV) oversizing of the aortic annular area [(THV external area/systolic annular area - 1) × 100; range, 1%-20%; target, 10%-15%]. Consecutive patients (n = 120) underwent CT before TAVR with balloon-expandable valves sized by transesophageal echocardiography (TEE). Retrospectively, the CT-recommended THV size was compared with the actual size implanted. RESULTS Compared with TEE, application of the newly developed CT-based sizing recommendations would have led to implantation of a larger valve in 33.3% (40/120), no change in valve size in 55.8% (67/120), and a smaller valve in 10.8% (13/120). In patients when CT recommended a larger valve, the incidence of at least moderate paravalvular regurgitation was 25% (10/40) compared with 4.5% (3/67; P < 0.01) when both TEE and CT recommendations were in agreement. Using diastolic versus systolic CT measurements results in 20% of patients receiving smaller THVs. TEE sizing resulted in 33.3% (40/120) of valves being undersized (THV area < CT systolic annular area) with a mean annular oversizing of 9.4% ± 17.4% (range: -21.5% to 65.9%) without annular rupture. In contrast, the CT sizing recommendations results in mean annular oversizing of 13.9% ± 8.0% (range, 1.3%-29.8%). CONCLUSION These CT sizing recommendations enable standardized moderate overexpansion of the aortic annulus. Clinical outcomes from these recommendations are being prospectively assessed in a multicenter trial.

Impact of Post-Implant SAPIEN XT Geometry and Position on Conduction Disturbances, Hemodynamic Performance, and Paravalvular Regurgitation

OBJECTIVES This report sought to study the impact of the balloon-expandable SAPIEN XT (Edwards Lifesciences, Irvine, California) transcatheter heart valve (THV) stent frame geometry and position on outcomes of transcatheter aortic valve replacement (TAVR). BACKGROUND Post-implant THV geometry and position might impact atrioventricular conduction, hemodynamic performance, and annular sealing. METHODS Eighty-nine consecutive patients who underwent TAVR with a Sapien XT THV had pre- and post-implant multidetector computed tomography, transthoracic echocardiography, and electrocardiograms performed to assess THV stent geometry, atrioventricular conduction, and hemodynamic performance. RESULTS The THV Circularity (THV eccentricity <10% [eccentricity = minimum stent diameter/maximum stent diameter]) and under-expansion (THV area/nominal THV area <90%) were present in 97.8% (2 of 89) and 0%, respectively. Low THV implantation was associated with new left bundle branch block and complete heart block (3.4 ± 2.0 mm vs. 5.5 ± 2.9 mm, p = 0.01) and with the need for permanent pacemaker implantation (3.5 ± 2.0 mm vs. 7.1 ± 2.5 mm, p = 0.001). In contrast, labeled THV size and THV area oversizing was not associated with atrioventricular conduction disturbances. The relation between inflow stent frame area and annular area was related to paravalvular regurgitation (p = 0.025). Labeled prosthesis size but not prosthesis expansion or eccentricity was related to valve gradient (p = 0.005) and effective orifice area (p < 0.001). CONCLUSIONS Low implantation depth of balloon-expandable THVs is associated with clinically significant new conduction disturbances and permanent pacemaker implantation. Importantly, annular area oversizing was not associated with these complications.

Effect of a novel vendor-specific motion-correction algorithm on image quality and diagnostic accuracy in persons undergoing coronary CT angiography without rate-control medications

BACKGROUND Although coronary CT angiography (CTA) shows high diagnostic performance for detection and exclusion of obstructive coronary artery disease, limited temporal resolution of current-generation CT scanners may allow for motion artifacts, which may result in nonevaluable coronary segments. OBJECTIVE We assessed a novel vendor-specific motion-correction algorithm for its effect on image quality and diagnostic accuracy. METHODS Thirty-six consecutive patients with severe aortic stenosis undergoing coronary CTA without rate control and invasive coronary angiography as part of an evaluation for transcatheter aortic valve replacement. We compared image quality and diagnostic accuracy between standard (STD) and motion-corrected (MC) reconstructions. Coronary CTAs were interpreted in an intent-to-diagnose fashion by 2 experienced readers; a third reader provided consensus for interpretability and obstructive coronary stenosis (≥50% stenosis). All studies were interpreted with and without motion correction using both 45% and 75% of the R-R interval for reconstructions. Quantitative coronary angiography was performed by a core laboratory. RESULTS Mean age was 83.0 ± 6.4 years; 47% were men. Overall image quality (graded 1-4) was higher with the use of MC versus STD reconstructions (2.9 ± 0.9 vs 2.4 ± 1.0; P < 0.001). MC reconstructions showed higher interpretability on a per-segment [97% (392/406) vs 88% (357/406); P < 0.001] and per-artery [96% (128/134) vs 84% (112/134); P = 0.002] basis, with no difference on a per-patient level [92% (33/36) vs 89% (32/36); P = 1.0]. Diagnostic accuracy by MC reconstruction was higher than STD reconstruction on a per-segment [91% (370/406) vs 78% (317/406); P < 0.001] and per-artery level [86% (115/134) vs 72% (96/134); P = 0.007] basis, with no significant difference on a per-patient level [86% (31/36) vs 69% (25/36); P = 0.16]. CONCLUSIONS The use of a novel MC algorithm improves image quality, interpretability, and diagnostic accuracy in persons undergoing coronary CTA without rate-control medications.

Coronary Artery Imaging with Single-Source Rapid Kilovolt Peak–Switching Dual-Energy CT

PURPOSE To evaluate beam-hardening (BH) artifact reduction in coronary computed tomography (CT) angiography with dual-energy CT, to define the optimal monochromatic-energy levels for coronary and myocardial signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in dual-energy CT, and to compare these levels with single-energy CT. MATERIALS AND METHODS The study was approved by the institutional review board and/or ethics committee at each site. Patients provided informed consent. Thirty-nine patients were prospectively enrolled to undergo dual-energy CT, and 25 also underwent single-energy CT. Myocardial and coronary SNR, CNR, and iodine concentration were measured across multiple segments at varying monochromatic energy levels (40-140 keV). BH was defined as signal decrease in basal inferior wall versus midinferior wall, and signal increase in midseptum versus midinferior wall. Generalized estimating equation was used to identify optimal monochromatic-energy levels and compare them with single-energy CT. RESULTS BH was noted at single-energy CT with basal inferior wall mean reduction of 19.7 HU ± 29.2 (standard deviation) and midseptum increase of 46.3 HU ± 36.3. There was reduction in this artifact at 90 keV or greater (1.7 HU ± 18.4 in basal inferior wall and 20.1 HU ± 37.5 in midseptum at 90 keV; P < .05). SNR and CNR were higher in the myocardium and coronary arteries at 60-80 keV than single-energy CT (myocardium: SNR, 3.02 vs 2.39, and CNR, 6.73 vs 5.16; coronary arteries: SNR, 10.83 vs 7.75, and CNR, 13.31 vs 9.54; P < .01). Mean iodine concentration in resting myocardium was 2.19 mg/mL ± 0.57. CONCLUSION Rapid kilovolt peak-switching dual-energy CT resulted in significant BH reduction and improvements in SNR and CNR in the myocardium and coronary arteries.

Predictors of Mortality and Progression in Scleroderma-Associated Interstitial Lung Disease: A Systematic Review

BACKGROUND Interstitial lung disease (ILD) is the leading cause of morbidity and mortality in patients with systemic sclerosis (SSc); however, prognostication of SSc-associated ILD (SSc-ILD) remains challenging. We conducted a systematic review to identify variables that predict mortality and ILD progression in SSc-ILD. METHODS Three databases were searched to identify all studies relating to predictors of mortality or ILD progression in SSc-ILD. Studies were eligible if they were published in English and included ≥ 10 adults with SSc-ILD. Two authors independently reviewed and extracted data from acceptable studies. RESULTS The initial search identified 3,145 unique citations. Twenty-seven studies, including six abstracts, met the inclusion criteria. A total of 1,616 patients with SSc-ILD were included. Patient-specific, ILD-specific, and SSc-specific variables predicted mortality and progression; however, most predictors were identified in only one study. Most studies did not fully account for potential confounders, and none of the studies included a validation cohort. Older age, lower FVC, and lower diffusing capacity of carbon monoxide predicted mortality in more than one study. Male sex, extent of disease on high-resolution CT (HRCT) scan, presence of honeycombing, elevated KL-6 values, and increased alveolar epithelial permeability were identified as predictors of both mortality and ILD progression on unadjusted analysis. The extent of disease on HRCT scan was the only variable that independently predicted both mortality and ILD progression. CONCLUSIONS Mortality and ILD progression were predicted by several patient-specific, ILD-specific, and SSc-specific factors. Additional prospective studies are required to validate these preliminary findings and to identify combinations of variables that accurately predict the prognosis of SSc-ILD.