Evaluation of right ventricular function by coronary computed tomography angiography using a novel automated 3D right ventricle volume segmentation approach: a validation study.

OBJECTIVES: To evaluate right ventricle (RV) function by coronary computed tomography angiography (CTA) using a novel automated three-dimensional (3D) RV volume segmentation tool in comparison with clinical reference modalities. METHODS: Twenty-six patients with severe end-stage heart failure [left ventricle (LV) ejection fraction (EF) <35%] referred to CTA were enrolled. A specific individually tailored biphasic contrast agent injection protocol was designed (80%/20% high/low flow) was designed. Measurement of RV function [EF, end-diastolic volume (EDV), end-systolic volume (ESV)] by CTA was compared with tricuspid annular plane systolic excursion (TAPSE) by transthoracic echocardiography (TTE) and right heart invasive catheterisation (IC). RESULTS: Automated 3D RV volume segmentation was successful in 26 (100%) patients. Read-out time was 3 min 33 s (range, 1 min 50s-4 min 33s). RV EF by CTA was stronger correlated with right atrial pressure (RAP) by IC (r = -0.595; p = 0.006) but weaker with TAPSE (r = 0.366, p = 0.94). When comparing TAPSE with RAP by IC (r = -0.317, p = 0.231), a weak-to-moderate non-significant inverse correlation was found. Interobserver correlation was high with r = 0.96 (p < 0.001), r = 0.86 (p < 0.001) and r = 0.72 (p = 0.001) for RV EDV, ESV and EF, respectively. CT attenuation of the right atrium (RA) and right ventricle (RV) was 196.9 ± 75.3 and 217.5 ± 76.1 HU, respectively. CONCLUSIONS: Measurement of RV function by CTA using a novel 3D volumetric segmentation tool is fast and reliable by applying a dedicated biphasic injection protocol. The RV EF from CTA is a closer surrogate of RAP than TAPSE by TTE. KEY POINTS: • Evaluation of RV function by cardiac CTA by using a novel 3D volume segmentation tool is fast and reliable. • A biphasic contrast agent injection protocol ensures homogenous RV contrast attenuation. • Cardiac CT is a valuable alternative modality to CMR for the evaluation of RV function.

Computed tomography in patients with tricuspid regurgitation prior to transcatheter valve repair: dynamic analysis of the annulus with an individually tailored contrast media protocol.

AIMS: The aim of this study is to present a contrast media (CM) protocol for the dynamic visualisation of the tricuspid valve (TV) and tricuspid annulus (TA) with CT. METHODS AND RESULTS: Fifteen patients with no cardiac abnormalities (controls), 15 patients with functional tricuspid regurgitation (FTR) <3+, and 13 patients with FTR ≥3+ underwent a dedicated cardiac CT protocol. Using advanced visualisation, segmentation and analysis software, the annular area, entire annular circumference, its three parts, and annular diameters were measured by two independent, blinded readers. The homogeneity of attenuation in the right heart was 63 HU in the RA and 46 HU in the RV, showing a significant negative correlation with the degree of FTR (r=-0.61, p<0.001). The annular area, entire annulus and diameters were larger in patients with FTR compared to controls (p<0.05). There were significant differences between systole and diastole in controls and patients with FTR <3+ and FTR ≥3+ for the annular area and annulus (p<0.05). The annulus was significantly smaller (all, p<0.05) in 2D compared to 3D (systematic underestimation: 1.0-1.3 mm), the difference decreasing with increasing FTR grades. CONCLUSIONS: This study introduces an individually tailored CM protocol for optimised visualisation of the TV with CT. We found dynamic changes of the geometry within the cardiac cycle and between 3D and 2D measurements, the latter systematically underestimating the true size of the TA. Use of this CM protocol enables accurate imaging of the dynamic geometry of the TA prior to transcatheter valve repair.

The high-risk criteria low-attenuation plaque <60 HU and the napkin-ring sign are the most powerful predictors of MACE: a long-term follow-up study.

AIMS: To assess the prognostic value of coronary CT angiography (CTA) for prediction of major adverse cardiac events (MACE) over a long-term follow-up period. METHODS AND RESULTS: A total of 1469 low-to-intermediate-risk patients (65.9 years; 44.2% females) were included in our prospective cohort study. CTA was evaluated for (i) stenosis severity (minimal <10%; mild <50%; moderate 50-70%; severe >70%), (ii) plaque types (calcified, mixed dominantly calcified, mixed dominantly non-calcified, non-calcified), and (iii) high-risk plaque criteria [low-attenuation plaque (LAP) quantified by HU, napkin-ring (NR) sign, spotty calcification <3 mm, and remodelling index (RI)]. Over a follow-up of mean 7.8 years, MACE rate was 41 (2.8%) and 0% in patients with negative CTA. MACE rate increased along with stenosis severity by CTA (from 1.3 to 7.8%) (P < 0.001) and was higher in T3/T4 plaques than in T2/T1 (7.8 vs. 1.9%; P < 0.0001). LAP density was lower (35.2 HU ± 32 vs. 108.8 HU ± 53) (P < 0.001) and both NR-sign prevalence with n = 26 (63.4%) vs. n = 40 (28%) and LAP <30, <60, and <90 HU prevalence with 46.3-78% vs. 2.4-7% were higher in the MACE group (P < 0.001). On univariate and unadjusted multivariable proportional Hazards model, LAP <60 HU and NR were the strongest MACE predictors (HR 4.96; 95% CI: 2.0-12.2 and HR 3.85; 95% CI: 1.7-8.6) (P < 0.0001), while spotty calcification (HR 2.2; 95% CI: 1.1-4.3, P < 0.001), stenosis severity, and plaque type (HR 1.5; 95% CI: 1.1-2.3 and HR 1.7; 95% CI: 1.1-2.6) (P < 0.001) were less powerful. After adjusting for risk factors, CTA stenosis severity, and plaque type, LAP <60 HU and the NR sign remained significant (P < 0.001), while the effect of NR sign was even enhancing. HRP criteria were independent predictors from other risk factors. CONCLUSION: Prognosis is excellent over a long-term period if CTA is negative and worsening with an increasing non-calcifying plaque component. LAP <60 HU and NR sign are the most powerful MACE predictors.

Quantitative coronary CT angiography: absolute lumen sizing rather than %stenosis predicts hemodynamically relevant stenosis.

OBJECTIVE: To identify the most accurate quantitative coronary stenosis parameter by CTA for prediction of functional significant coronary stenosis resulting in coronary revascularization. METHODS: 160 consecutive patients were prospectively examined with CTA. Proximal coronary stenosis was quantified by minimal lumen area (MLA) and minimal lumen diameter (MLD), %area and %diameter stenosis. Lesion length (LL) was measured. The reference standard was invasive coronary angiography (ICA) (>70 % stenosis, FFR <0.8). RESULTS: 210 coronary segments were included (59 % positive). MLA of ≤1.8 mm2 was identified as the optimal cut-off (c = 0.97, p < 0.001; 95 % CI 0.94-0.99) (sensitivity 90.9 %, specificity 89.3 %) for prediction of functional-relevant stenosis (for MLA >2.1 mm2 sensitivity was 100 %). The optimal cut-off for MLD was 1.2 mm (c = 0.92; p < 0.001; 95 % CI 0.88-95) (sensitivity 90.9, specificity 85.2) while %area and %diameter stenosis were less accurate (c = 0.89; 95 % CI 0.84-93, c = 0.87; 95 % CI 0.82-92, respectively, with thresholds at 73 % and 61 % stenosis). Accuracy for LL was c = 0.74 (95 % CI 0.67-81), and for LL/MLA and LL/MLD ratio c = 0.90 and c = 0.84. CONCLUSIONS: MLA ≤1.8 mm2 and MLD ≤1.2 mm are the most accurate cut-offs for prediction of haemodynamically significant stenosis by ICA, with a higher accuracy than relative % stenosis. KEY POINTS: • Quantitative coronary CT-angiography is accurate for prediction of functional relevant stenosis. • Absolute lumen area and diameter rather than %stenosis predict functional relevance. • Lumen area <1.8 mm 2 and diameter <1.2 mm are the most accurate cut-offs. • Quantitative parameters are helpful for decision-making in terms of patient management.

Improved non-calcified plaque delineation on coronary CT angiography by sonogram-affirmed iterative reconstruction with different filter strength and relationship with BMI.

PURPOSE: To prospectively compare non-calcified plaque delineation and image quality of coronary computed tomography angiography (CCTA) obtained with sinogram-affirmed iterative reconstruction (IR) with different filter strengths and filtered back projection (FBP). METHODS: A total of 57 patients [28.1% females; body mass index (BMI) 29.2±6.5 kg/m(2)] were investigated. CCTA was performed using 128-slice dual-source CT. Images were reconstructed with standard FBP and sinogram-affirmed IR using different filter strength (IR-2, IR-3, IR-4) (SAFIRE, Siemens, Germany). Image quality of CCTA and a non-calcified plaque outer border delineation score were evaluated by using a 5-scale score: from 1= poor to 5= excellent. Image noise, contrast-to-noise ratio (CNR) of aortic root, left main (LM) and right coronary artery, and the non-calcified plaque delineation were quantified and compared among the 4 image reconstructions, and were compared between different BMI groups (BMI <28 and ≥28). Statistical analyses included one-way analysis of variance (ANOVA), least significant difference (LSD) and Kruskal-Wallis test. RESULTS: There were 71.9% patients in FBP, 96.5% in IR-2, 96.5% in IR-3 and 98.2% in IR-4 who had overall CCTA image quality ≥3, and there were statistical differences in CCTA exam image quality score among those groups, respectively (P<0.001). Sixty-one non-calcified plaques were detected by IR-2 to IR-4, out of those 11 (18%) were missed by FBP. Plaque delineation score increased constantly from FBP (2.7±0.4) to IR-2 (3.2±0.3), to IR-3 (3.5±0.3) up to IR-4 (4.0±0.4), while CNRs of the non-calcifying plaque increased and image noise decreased, respectively. Similarly, CNR of aortic root, LM and right coronary artery improved and image noise declined from FBP to IR-2, IR-3 and IR-4. There were no significant differences of image quality and plaque delineation score between low and high BMI groups within same reconstruction (all P>0.05). Significant differences in image quality and plaque delineation scores among different image reconstructions both in low and high BMI groups (all P<0.001) were found. I4f revealed the highest image quality and plaque delineation score. CONCLUSIONS: IR offers improved image quality and non-calcified plaque delineation as compared with FBP, especially if BMI is increasing. Importantly, 18% of non-calcified plaques were missed with FBP. IR-4 shows the best image quality score and plaque delineation score among the different IR-filter strength.