Stefan Baumann

Comparison of Diagnostic Value of a Novel Noninvasive Coronary Computed Tomography Angiography Method Versus Standard Coronary Angiography for Assessing Fractional Flow Reserve

Noninvasive fractional flow reserve (FFR) from coronary computed tomography angiography (cCTA) correlates well with invasive FFR and substantially improves the detection of obstructive coronary artery disease. However, with current algorithms, computed tomography (CT)-based FFR is derived off-site in an involved time-consuming manner. We sought to investigate the diagnostic performance of a novel CT-based FFR algorithm, developed for time-efficient in-hospital evaluation of hemodynamically indeterminate coronary lesions. In a blinded fashion, CT-based FFR was assessed in 67 coronary lesions of 53 patients. Pressure guidewire-based FFR <0.80 served as the reference standard to define hemodynamically significant stenosis and assess the diagnostic performance of CT-based FFR compared with standard evaluation of cCTA (luminal diameter stenosis of ≥50%). We recorded the time needed for derivation of CT-based FFR. On a per-lesion and per-patient basis, CT-based FFR resulted in a sensitivity of 85% and 94%, a specificity of 85% and 84%, a positive predictive value of 71% and 71%, and a negative predictive value of 93% and 97%, respectively. The area under the receiver operating characteristic curve on a per-lesion basis was significantly greater for CT-based FFR compared with standard evaluation of cCTA (0.92 vs 0.72, pxa0= 0.0049). Axa0similar trend, albeit not statistically significant, was observed on per-patient analysis (0.91 vs 0.78, pxa0= 0.078). Mean total time for CT-based FFR was 37.5 ± 13.8xa0minutes. In conclusion, the CT-based FFR algorithm evaluated here outperforms standard evaluation of cCTA for the detection of hemodynamically significant stenoses while allowing on-site application within clinically viable time frames.

Coronary CT angiography-derived fractional flow reserve correlated with invasive fractional flow reserve measurements – initial experience with a novel physician-driven algorithm

AbstractObjectivesThe present study aimed to determine the feasibility of a novel fractional flow reserve (FFR) algorithm based on coronary CT angiography (cCTA) that permits point-of-care assessment, without data transfer to core laboratories, for the evaluation of potentially ischemia-causing stenoses.MethodsTo obtain CT-based FFR, anatomical coronary information and ventricular mass extracted from cCTA datasets were integrated with haemodynamic parameters. CT-based FFR was assessed for 36 coronary artery stenoses in 28 patients in a blinded fashion and compared to catheter-based FFR. Haemodynamically relevant stenoses were defined by an invasive FFR ≤0.80. Time was measured for the processing of each cCTA dataset and CT-based FFR computation. Assessment of cCTA image quality was performed using a 5-point scale.ResultsMean total time for CT-based FFR determination was 51.9u2009±u20099.0xa0min. Per-vessel analysis for the identification of lesion-specific myocardial ischemia demonstrated good correlation (Pearson’s product-moment ru2009=u20090.74, pu2009<u20090.0001) between the prototype CT-based FFR algorithm and invasive FFR. Subjective image quality analysis resulted in a median score of 4 (interquartile ranges, 3-4).ConclusionsOur initial data suggest that the CT-based FFR method for the detection of haemodynamically significant stenoses evaluated in the selected population correlates well with invasive FFR and renders time-efficient point-of-care assessment possible.Key Points• CT-based FFR computation is a promising novel non-invasive application.n • A novel prototype algorithm permits time-efficient point-of-care CT-based FFR assessment.n • Initial results of the CT-based FFR prototype algorithm compare favourably with FFR.

Diagnostic value of quantitative stenosis predictors with coronary CT angiography compared to invasive fractional flow reserve

OBJECTIVEnTo evaluate the diagnostic performance of CCTA-derived stenosis predictors including CT-FFR for the detection of ischemia-inducing stenosis compared to invasive FFR.nnnMATERIALS AND METHODSnStenosis parameters were assessed using dual-source CT (DSCT). All patients underwent both CCTA and invasive FFR within 3 months and were retrospectively analyzed. Observers visually assessed all CCTA studies and performed multiple lesion measurements. Lesion length/minimal luminal diameter(4) (LL/MLD(4)), transluminal attenuation gradient (TAG), corrected coronary attenuation (CCO) and CT-FFR were calculated.nnnRESULTSnThe cohort included 32 patients (58±12 years, 66%male). Among 32 coronary lesions, 8 (25%) were considered hemodynamically significant with an FFR <0.80. Compared to invasive FFR, the per-vessel sensitivity and specificity of CCTA, CT-FFR, LL/MLD(4), CCO and TAG for detecting hemodynamically significant lesions were 100% and 54%, 100% and 91%, 85% and 92%, 66% and 88%, 37% and 58%, respectively. Receiver operating characteristics analysis resulted in an area under the curve of 0.91 for CT-FFR (p=0.0005), 0.88 for LL/MLD(4) (p<0.0001), 0.85 for CCO (p<0.0001). TAG with an AUC of 0.67 (p=0.152) was unable to discriminate between vessels with or without hemodynamically significant lesions.nnnCONCLUSIONnCT-FFR, LL/MLD(4) and CCO provide enhanced diagnostic performance over CCTA analysis alone for discrimination of hemodynamically significant coronary stenosis.

Coronary CT angiography derived morphological and functional quantitative plaque markers correlated with invasive fractional flow reserve for detecting hemodynamically significant stenosis.

OBJECTIVEnCompare morphological and functional coronary plaque markers derived from coronary CT angiography (CCTA) for their ability to detect lesion-specific ischemia.nnnMATERIALS AND METHODSnData of patients who had undergone both dual-source CCTA and invasive fractional flow reserve (FFR) measurement within 3 months were retrospectively analyzed. Various quantitative stenosis markers were derived from CCTA: Corrected coronary opacification (CCO), transluminal attenuation gradient (TAG), remodeling index (RI), computational FFR (cFFR), lesion length (LL), vessel volume (VV), total plaque volume (TPV), and calcified and non-calcified plaque volume (CPV and NCPV). Discriminatory power of these markers for flow-limiting versus non-significant coronary stenosis was assessed against invasive FFR as the reference standard.nnnRESULTSnThe cohort included 37 patients (61xa0±xa012xa0years, 68% male). Among 37 lesions, 11 were hemodynamically significant by FFR. On a per-lesion level, sensitivity and specificity of TPV, CPV, and NCPV for hemodynamically significant stenosis detection were 88% and 74%, 67% and 53%, and 92% and 81%, respectively. For CCO, TAG, RI, and cFFR these were 64% and 86%, 35% and 56%, 82% and 54%, and 100% and 90%, respectively. At ROC analysis, only TPV (0.78, pxa0=xa00.013), NCPV (0.79, pxa0=xa00.009), cFFR (0.85, pxa0=xa00.003), and CCO (0.82, pxa0=xa00.0003) showed discriminatory power for detecting hemodynamically significant stenosis.nnnCONCLUSIONnTPV, NCPV, CCO, and cFFR derived from CCTA can aid detecting hemodynamically significant coronary lesions with cFFR showing the greatest discriminatory ability.

A non-contrast self-navigated 3-dimensional MR technique for aortic root and vascular access route assessment in the context of transcatheter aortic valve replacement: proof of concept

ObjectivesDue to the high prevalence of renal failure in transcatheter aortic valve replacement (TAVR) candidates, a non-contrast MR technique is desirable for pre-procedural planning. We sought to evaluate the feasibility of a novel, non-contrast, free-breathing, self-navigated three-dimensional (SN3D) MR sequence for imaging the aorta from its root to the iliofemoral run-off in comparison to non-contrast two-dimensional-balanced steady-state free-precession (2D-bSSFP)xa0imaging.MethodsSN3Dxa0[field of view (FOV), 220-370xa0mm3; slice thickness, 1.15xa0mm; repetition/echo time (TR/TE), 3.1/1.5xa0ms; and flip angle, 115°] and 2D-bSSFP acquisitions (FOV, 340xa0mm; slice thickness, 6xa0mm; TR/TE, 2.3/1.1xa0ms; flip angle, 77°) were performed in 10 healthy subjects (all male; mean age, 30.3u2009±u20094.3xa0yrs) using a 1.5-T MRI system. Aortic root measurements and qualitative image ratings (four-point Likert-scale) were compared.ResultsThe mean effective aortic annulus diameter was similar for 2D-bSSFP and SN3D (26.7u2009±u20090.7 vs. 26.1u2009±u20090.9xa0mm, pu2009=u20090.23). The mean image quality of 2D-bSSFP (4; IQR 3-4) was rated slightly higher (pu2009=u20090.03) than SN3D (3; IQR 2-4). The mean total acquisition time for SN3D imagingxa0was 12.8u2009±u20092.4xa0min.ConclusionsOur results suggest that a novel SN3D sequence allows rapid, free-breathing assessment of the aortic root and the aortoiliofemoral system without administration of contrast medium.Key Points• The prevalence of renal failure is high among TAVR candidates.• Non-contrast 3D MR angiography allows for TAVR procedure planning.• The self-navigated sequence provides a significantly reduced scanning time.

Mammographic detection of breast arterial calcification as an independent predictor of coronary atherosclerotic disease in a single ethnic cohort of African American women

OBJECTIVEnAccumulating data on predominantly Caucasian women suggests an association between breast arterial calcification (BAC) and coronary artery disease (CAD). We sought to comprehensively examine the correlation between mammographic BAC and CAD endpoints detected by cardiac computed tomography (CCT) in African American (AA) women.nnnMETHODSnConsecutive AA women who underwent digital screening mammography and CCT were identified. In blinded fashion, mammographic and CCT studies were reviewed. Patient-related pertinent covariates were assessed.nnnRESULTSnTwo-hundred-four AA women (median age, 52.5 years) were included. BAC was present in 42 women (20.6%). BAC was significantly associated with coronary artery calcium score >100 (odds ratio [OR], 7.66; 95% confidence interval [CI], 2.75-21.29; P < 0.001), atherosclerotic luminal narrowing (OR, 9.99; CI, 3.65-27.32; P < 0.001), and stenosis ≥50% (OR, 5.48; CI, 1.97-15.23; P = 0.001) by CCT.nnnCONCLUSIONnIn AA women, BAC is associated with increased probability of coronary calcification, atherosclerosis, and CAD on CCT.

Computed Tomography Imaging of Coronary Artery Plaque: Characterization and Prognosis

The exact definition and prognostication of vulnerable plaque remain elusive, and multiple imaging modalities aim to identify these plaques. As a noninvasive technique for the diagnosis of coronary artery disease, coronary computed tomography angiography has become increasingly utilized, primarily in patients with an elevated cardiovascular risk profile. Recent advances in technical methods have allowed for improved visualization of the vessel wall and surrounding tissue, allowing for improved characterization of vulnerable plaques by identifying features such as low-density plaques, positive remodeling, and spotty calcification. Quantification and qualification of these plaques may enhance the ability to predict future cardiovascular events.

Comparison of Coronary Computed Tomography Angiography-Derived vs Invasive Fractional Flow Reserve Assessment: Meta-Analysis with Subgroup Evaluation of Intermediate Stenosis

RATIONALE AND OBJECTIVESnInvasive coronary angiography (ICA) with fractional flow reserve (FFR) assessment is the reference standard for the detection of hemodynamically relevant coronary lesions. We have investigated whether coronary computed tomography angiography (cCTA)-derived FFR (fractional flow reserve from coronary computed tomographic angiography [CT-FFR]) measurement improves diagnostic accuracy over cCTA.nnnMETHODS AND RESULTSnA literature search was performed for studies comparing invasive FFR, cCTA, and CT-FFR. The analysis included three prospective multicenter trials and two retrospective single-center studies; a total of 765 patients and 1306 vessels were included in the meta-analysis. Compared to invasive FFR on a per-lesion basis, CT-FFR reached a pooled sensitivity, specificity, positive predictive value, and negative predictive value of 83.7% (95% confidence interval [CI]: 78.1-89.3), 74.7% (95% CI: 52.2-97.1), 64.8% (95% CI: 52.1-77.5), and 90.1% (95% CI: 80.8-99.3) compared to 84.6% (95% CI: 78.1-91.1), 49.7% (95% CI: 31.1-68.4), 39.0% (95% CI: 28.0-50.1), and 87.3% (95% CI: 72.5-100.0) for cCTA alone. In 634 vessels with intermediate stenosis (30%-70%), sensitivity, specificity, positive predictive value, and negative predictive value were 81.4% (95% CI: 70.4-92.9), 71.7% (95% CI: 54.5-89.0), 59.4% (95% CI: 35.5-83.4), and 89.9% (95% CI: 85.0-94.7) compared to 90.2% (95% CI: 80.6-99.9), 35.4% (95% CI: 23.5-47.3), 50.7% (95% CI: 30.6-70.8), and 82.5% (95% CI: 64.5-100.0) for cCTA alone. The summary area under the receiver operating characteristic curve of CT-FFR was superior to cCTA alone on a per-vessel (0.90 [95% CI: 0.82-0.98] vs 0.74 [95% CI: 0.63-0.86]; Pu2009=u2009.0047) and for intermediate stenoses (0.76 [95% CI: 0.65-0.88] vs 0.57 [95% CI: 0.49-0.66]; Pu2009=u2009.0027).nnnCONCLUSIONnCT-FFR significantly improves specificity without noticeably altering the sensitivity of cCTA with invasive FFR as a reference standard for the detection of hemodynamically relevant stenosis.

Comparison of quantitative stenosis characteristics at routine coronary computed tomography angiography with invasive fractional flow reserve for assessing lesion-specific ischemia

OBJECTIVEnTo comprehensively evaluate quantitative parameters derived from routine coronary CT angiography (cCTA) for predicting lesion-specific ischemia in comparison to invasive fractional flow reserve (FFR).nnnBACKGROUNDnThe ability of cCTA to gauge lesion-specific ischemia is limited. Several quantitative parameters have been proposed to enhance the specificity of cCTA, such as morphologic indices (lesion length/minimal lumen diameter(4) [LL/MLD(4)]; percentage aggregate plaque volume [%APV]) and a measure of intracoronary contrast gradients (corrected coronary opacification [CCO]).nnnMETHODSnForty-nine patients who had undergone cCTA followed by FFR within 3 months were included. An experienced observer visually assessed all cCTA studies and derived multiple measures characterizing the lesion of interest, including LL, MLD, minimal lumen area (MLA), LL/MLD(4), remodeling index, %APV, and CCO. Lesion-specific ischemia was considered with FFR <0.8.nnnRESULTSnAmong 56 lesions, 13 were flow-obstructing by FFR. On univariate analysis, LL, MLD, LL/MLD(4), and CCO showed discriminatory power. The area under the curve of LL/MLD(4) (0.909) was significantly greater compared with MLD (0.802, P = 0.014), LL (0.739, P = 0.041), and CCO (0.809), although the latter did not reach statistical significance (P = 0.175). On multivariate regression, LL/MLD(4) was the only independent predictor of lesion-specific ischemia (odds ratio 2.021, P = 0.001). Moreover, LL/MLD(4) compared favorably to visual cCTA evaluation.nnnCONCLUSIONnLL/MLD(4) derived from routine cCTA can enhance the detection of lesion-specific ischemia and may be superior to other described quantitative parameters.

[Computed tomography in patients with chronic stable angina : Fractional flow reserve measurement].

ZusammenfassungDie koronare CT-Angiographie (cCTA) hat sich als nichtinvasive Methode zur direkten Darstellung von Erkrankungen der Herzkranzgefäße (KHK) etabliert. Mithilfe dieses Verfahrens konnte in früheren Studien eine KHK mit hoher Wahrscheinlichkeit ausgeschlossen werden. Limitierend beim Einsatz der cCTA erscheint jedoch, dass sich viele visuell signifikant eingeschätzte Stenosen, gemessen an der invasiv ermittelbaren fraktionellen Flussreserve (FFR), als nicht hämodynamisch relevant erweisen. Als eine im Vergleich zur myokardialen CT-Perfusion vielversprechende Methode zur besseren Erfassung der funktionellen Bedeutung von Koronarstenosen stellt sich die auf Erkenntnissen der numerischen Strömungsmechanik und bildbasierter Simulation beruhende, CT-basierte FFR (CT-FFR) dar. Die CT-FFR kann aus regulären CT-Datensätzen, ohne zusätzliche Bildakquisition, Kontrastmittel- oder Medikamentengabe, bestimmt werden. Es werden zwei unterschiedliche Techniken zur Ermittlung der CT-FFR unterschieden. Das initiale Verfahren erfordert eine externe CT-FFR-Berechnung durch Hochleistungsrechner, wobei die behördliche Zulassung hierfür in den USA bereits erfolgt ist. Andererseits wurde ein Software-Prototyp beschrieben, der aufgrund der Integration vereinfachter Berechnungsmodelle geringere Rechnerkapazität erfordert und somit eine intrahospitale Anwendungsmöglichkeit bietet. Im folgenden Beitrag werden diese Verfahren im Kontext mit den jeweiligen Studienergebnissen und den Daten der Metaanalysen dargestellt. Des Weiteren werden sowohl methodische Einschränkungen und Zukunftsperspektiven der CT-FFR aufgezeigt.AbstractCoronary computed tomography angiography (cCTA) has been established for the non-invasive diagnosis of coronary artery disease (CAD). Previous studies demonstrated the high diagnostic accuracy of cCTA, particularly for ruling out CAD. As axa0known limitation of cCTA axa0large number of visually significant coronary stenoses are found to be hemodynamically not relevant by invasive fractional flow reserve (FFR). CT-based FFR (CT-FFR) builds on recent advances in computational fluid dynamics and image simulation techniques. Along with CT myocardial perfusion imaging, CT-FFR is axa0promising approach towards axa0more accurate estimation of the hemodynamic relevance of coronary artery stenoses. CT-FFR is derived from regular CT datasets without additional image acquisitions, contrast material, or medication. Two CT-FFR techniques can be differentiated. The initial method requires external use of supercomputers and has gained approval for clinical use in the USA. Furthermore, axa0prototype-software has been introduced which is less computationally demanding via integration of reduced-order models for on-site calculation of CT-FFR. The present article reviews these methods in the context of available study results and meta-analyses. Furthermore, limitations and future concepts of CT-FFR are discussed.Coronary computed tomography angiography (cCTA) has been established for the non-invasive diagnosis of coronary artery disease (CAD). Previous studies demonstrated the high diagnostic accuracy of cCTA, particularly for ruling out CAD. As axa0known limitation of cCTA axa0large number of visually significant coronary stenoses are found to be hemodynamically not relevant by invasive fractional flow reserve (FFR). CT-based FFR (CT-FFR) builds on recent advances in computational fluid dynamics and image simulation techniques. Along with CT myocardial perfusion imaging, CT-FFR is axa0promising approach towards axa0more accurate estimation of the hemodynamic relevance of coronary artery stenoses. CT-FFR is derived from regular CT datasets without additional image acquisitions, contrast material, or medication. Two CT-FFR techniques can be differentiated. The initial method requires external use of supercomputers and has gained approval for clinical use in the USA. Furthermore, axa0prototype-software has been introduced which is less computationally demanding via integration of reduced-order models for on-site calculation of CT-FFR. The present article reviews these methods in the context of available study results and meta-analyses. Furthermore, limitations and future concepts of CT-FFR are discussed.