Improving CCTA based lesions' hemodynamic significance assessment by accounting for partial volume modeling in automatic coronary lumen segmentation
Pith reviewed 2026-05-25 17:15 UTC · model grok-4.3
The pith
Accounting for partial volume effects in automatic coronary lumen segmentation from CCTA raises flow simulation specificity from 0.6 to 0.68 at fixed sensitivity of 0.83.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Integrating partial volume effect analysis into the automatic coronary lumen segmentation algorithm improves flow simulation specificity from 0.6 to 0.68 while keeping sensitivity at 0.83, and increases the area under the ROC curve for detecting hemodynamically significant CAD from 0.76 to 0.8 against invasive FFR threshold of 0.8.
What carries the argument
Partial volume effect (PVE) modeling added to the automatic coronary lumen segmentation algorithm, which refines the estimated lumen geometry to compensate for CT blurring before the geometry is passed to the flow simulation.
If this is right
- Fewer lesions diagnosed as obstructive on CCTA would be incorrectly flagged as needing invasive evaluation or revascularization.
- The overall accuracy of non-invasive CCTA-based hemodynamic assessment increases without changing the underlying flow solver.
- Segmentation accuracy measured by Dice or surface distance alone does not predict the clinical benefit; downstream flow simulation performance must be checked directly.
Where Pith is reading between the lines
- The same PVE correction step could be inserted into other vessel segmentation pipelines that feed into flow or pressure calculations.
- The observed gain may vary with scanner resolution or reconstruction kernel; testing on lower-resolution or motion-affected scans would quantify dependence.
- Independent validation on a multi-center cohort with different CT vendors would establish whether the specificity improvement generalizes beyond the study population.
Load-bearing premise
The computational flow simulation run on the segmented lumen geometry produces values that correctly match real-world hemodynamic significance as measured by invasive FFR.
What would settle it
On the same 76 cases, simulated FFR values derived from the PVE-adjusted segmentations diverge from the invasive FFR measurements in a direction that eliminates or reverses the reported gains in specificity and AUC.
Figures
read the original abstract
Purpose: The goal of this study was to assess the potential added benefit of accounting for partial volume effects (PVE) in an automatic coronary lumen segmentation algorithm from coronary computed tomography angiography (CCTA). Materials and methods: We assessed the potential added value of PVE integration as a part of the automatic coronary lumen segmentation algorithm by means of segmentation accuracy using the MICCAI 2012 challenge framework and by means of flow simulation overall accuracy, sensitivity, specificity, negative and positive predictive values and the receiver operated characteristic (ROC) area under the curve. We also evaluated the potential benefit of accounting for PVE in automatic segmentation for flow-simulation for lesions that were diagnosed as obstructive based on CCTA, which could have indicated a need for an invasive exam and revascularization. Results: Our segmentation algorithm improves the maximal surface distance error by ~39% compared to previously published method on the 18 datasets 50 from the MICCAI 2012 challenge with comparable Dice and mean surface distance. Results with and without accounting for PVE were comparable. In contrast, integrating PVE analysis into an automatic coronary lumen segmentation algorithm improved the flow simulation specificity from 0.6 to 0.68 with the same sensitivity of 0.83. Also, accounting for PVE improved the area under the ROC curve for detecting hemodynamically significant CAD from 0.76 to 0.8 compared to automatic segmentation without PVE analysis with invasive FFR threshold of 0.8 as the reference standard. The improvement in the AUC was statistically significant (N=76, Delong's test, p=0.012). Conclusion: Accounting for the partial volume effects in automatic coronary lumen segmentation algorithms has the potential to improve the accuracy of CCTA-based hemodynamic assessment of coronary artery lesions.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript describes an automatic coronary lumen segmentation algorithm from CCTA that incorporates partial volume effect (PVE) modeling. Segmentation performance is evaluated on the MICCAI 2012 challenge dataset (18 cases), showing a ~39% reduction in maximal surface distance error with comparable Dice and mean surface distance scores with/without PVE. Downstream, flow simulations on N=76 cases demonstrate improved specificity (0.6 to 0.68 at sensitivity 0.83) and AUC (0.76 to 0.8, Delong p=0.012) for detecting hemodynamically significant CAD (FFR threshold 0.8) when PVE is included.
Significance. If the reported gains hold under full methodological disclosure, the work could meaningfully improve CCTA-based non-invasive assessment of lesion hemodynamic significance by refining lumen geometry inputs to flow models, with potential to reduce false positives and unnecessary invasive exams. The use of an external challenge dataset for segmentation and independent invasive FFR as reference for the ROC analysis provides a reasonably grounded evaluation framework.
major comments (2)
- [Materials and methods] Materials and methods: The exact segmentation algorithm equations, PVE correction formulation, and integration steps are not specified. This is load-bearing for the central claim because the abstract states that Dice/mean surface distance remain comparable with/without PVE while flow-simulation specificity and AUC improve; without the equations it is impossible to determine whether the downstream gains arise from genuine lumen-geometry refinement or from unstated interactions between the PVE adjustment and the flow model.
- [Results] Results / flow simulation: No description is given of the flow model (boundary conditions, outlet resistances, steady vs. pulsatile assumptions, or rigid-wall approximation). Because the headline result (specificity 0.6→0.68, AUC 0.76→0.8) is obtained entirely through this model applied to the segmented geometries, the absence of these details leaves open the possibility that the statistically significant metric improvements reflect model-specific sensitivity to the small lumen-area changes induced by PVE rather than improved clinical assessment of hemodynamic significance.
minor comments (2)
- [Abstract] Abstract: The phrase “18 datasets 50 from the MICCAI 2012 challenge” appears to contain a typographical error and should be clarified.
- [Results] The manuscript does not report error bars, confidence intervals, or cross-validation details for the segmentation or flow-simulation metrics, which would aid interpretation of the reported numeric gains.
Simulated Author's Rebuttal
We thank the referee for the detailed and constructive feedback. The comments highlight important gaps in methodological transparency that we will address in revision. Below we respond point-by-point to the major comments.
read point-by-point responses
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Referee: [Materials and methods] The exact segmentation algorithm equations, PVE correction formulation, and integration steps are not specified. This is load-bearing for the central claim because the abstract states that Dice/mean surface distance remain comparable with/without PVE while flow-simulation specificity and AUC improve; without the equations it is impossible to determine whether the downstream gains arise from genuine lumen-geometry refinement or from unstated interactions between the PVE adjustment and the flow model.
Authors: We agree that the absence of the explicit equations and integration steps limits the ability to interpret the source of the observed improvements. In the revised manuscript we will add the full mathematical formulation of the automatic segmentation algorithm, the partial-volume-effect correction term, and the precise manner in which the corrected lumen surface is passed to the flow solver. This addition will make it possible to verify that the specificity and AUC gains originate from refined lumen geometry rather than from any hidden interaction with the downstream model. revision: yes
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Referee: [Results] Results / flow simulation: No description is given of the flow model (boundary conditions, outlet resistances, steady vs. pulsatile assumptions, or rigid-wall approximation). Because the headline result (specificity 0.6→0.68, AUC 0.76→0.8) is obtained entirely through this model applied to the segmented geometries, the absence of these details leaves open the possibility that the statistically significant metric improvements reflect model-specific sensitivity to the small lumen-area changes induced by PVE rather than improved clinical assessment of hemodynamic significance.
Authors: We acknowledge that a complete description of the flow-simulation pipeline is required to substantiate the clinical relevance of the reported gains. The revised manuscript will include the boundary conditions, outlet resistance assignment method, steady-flow assumption, and rigid-wall approximation employed. With these details provided, readers will be able to assess whether the specificity and AUC improvements are attributable to more accurate lumen geometry or to particular sensitivities of the chosen flow model. revision: yes
Circularity Check
No significant circularity; central claims rest on external validation against MICCAI dataset and independent invasive FFR
full rationale
The paper's derivation chain consists of (1) automatic lumen segmentation with/without PVE modeling, (2) application of a flow simulation model to the resulting geometries, and (3) direct comparison of simulated hemodynamics to invasive FFR ground truth on an external cohort of 76 lesions. Segmentation accuracy is benchmarked on the public MICCAI 2012 challenge set; flow-simulation metrics (specificity 0.6→0.68, AUC 0.76→0.8, Delong p=0.012) are likewise computed against independent FFR measurements. No equation, fitted parameter, or self-citation reduces these reported gains to quantities defined inside the paper itself. The flow model is treated as an external black-box predictor whose validity is an assumption, not a tautology internal to the derivation.
Axiom & Free-Parameter Ledger
free parameters (1)
- PVE correction parameters
axioms (2)
- domain assumption Partial volume effects in CCTA can be modeled to improve lumen boundary estimation
- domain assumption Flow simulation on segmented lumen geometry predicts hemodynamic significance
Reference graph
Works this paper leans on
-
[1]
Introduction: Coronary artery disease (CAD) is the single leading cause of death worldwide, accounting for 11.2% of all deaths globally in 2011.1 Among the non-invasive tests available for patients with suspected CAD, Coronary Computed Tomography Angiography (CCTA) is a rapidly evolving technique to rule out CAD due to its high negative predictive value.2...
work page 2011
-
[2]
Datasets: We used two data sets as follows
Materials and methods: 2.A. Datasets: We used two data sets as follows. The first dataset was the publicly available MICCAI 2012 coronary artery segmentation challenge database. The database consists of 48 CCTA datasets that were acquired from a representative selection of CAD symptomatic patients using several cardiac CT scanners from different vendors w...
work page 2012
-
[3]
The coronary-artery centerlines
-
[4]
The segmentation of the aortic root 10 The coronary artery centerlines and the aorta segmentation were computed automatically and adjusted manually by a cardiac CT expert (M.V) to account for algorithm inaccuracies using a commercially available software dedicated for cardiac image analysis (Comprehensive Cardiac Analysis, IntelliSpace Portal 6.0, Philips...
-
[5]
Evaluation 3.A. Methodology: We implemented our main algorithm in C++ using the graph min-cut solver of Boykov et al25, and an accelerated approximate K-nearest neighbor search.24 We experimentally set the value of the regularization term 𝜆 in Eq. 5 to 1.75 and 𝐾 in Eq. 6 to 100. The average running time to segment the entire coronary tree lumen for each ...
work page 2012
-
[6]
and 𝐾 (Eq. 6). We assessed the sensitivity of our algorithm to the two key parameters in our algorithm by using the training data available from the MICCAI 2012 challenge dataset. 12 3.A.3. Impact of accounting for PVE on simulated FFR performance Next, we assessed the performance of simulated FFR measurements based on automatically generated coronary 3D ...
work page 2012
-
[7]
Discussion: Our study demonstrates the importance of accounting for PVE in automatic coronary segmentation algorithms used to determine the hemodynamic significance of coronary artery stenosis by CCTA based on flow simulations. Quantitative analysis of the CAD from CCTA required both automatic extraction of the coronaries’ centerlines30–34 and automatic s...
work page 2012
-
[8]
Nowbar AN, Howard JP, Finegold JA, Asaria P, Francis DP. 2014 Global geographic analysis of mortality from ischaemic heart disease by country, age and income: Statistics from World Health Organisation and United Nations. Int J Cardiol. 2014;174(2):293-298. doi:10.1016/j.ijcard.2014.04.096
-
[9]
Scot-heart T. CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial. Lancet. 2015;385(9985):2383-2391. doi:10.1016/S0140- 6736(15)60291-4
-
[10]
Comprehensive Assessment of Coronary Artery Stenoses
Meijboom WB, Van Mieghem CAG, van Pelt N, et al. Comprehensive Assessment of Coronary Artery Stenoses. Computed Tomography Coronary Angiography Versus Conventional Coronary Angiography and Correlation With Fractional Flow Reserve in Patients With Stable Angina. J Am Coll Cardiol. 2008;52(8):636-643. doi:10.1016/j.jacc.2008.05.024
-
[11]
Gonzalez JA, Lipinski MJ, Flors L, Shaw PW, Kramer CM, Salerno M. Meta- analysis of diagnostic performance of coronary computed tomography angiography, computed tomography perfusion, and computed tomography- fractional flow reserve in functional myocardial ischemia assessment versus invasive fractional flow reserve. Am J Cardiol. 2015;116(9):1469-1478. do...
-
[12]
Nørgaard BL, Leipsic J, Gaur S, et al. Diagnostic performance of non-invasive fractional flow reserve derived from coronary CT angiography in suspected coronary artery disease: The NXT trial. J Am Coll Cardiol. 2014;63(12):1145- 33
work page 2014
-
[13]
doi:10.1016/j.jacc.2013.11.043
-
[14]
Min JK, Taylor CA, Achenbach S, et al. Noninvasive fractional flow reserve derived from coronary CT angiography clinical data and scientific principles. JACC Cardiovasc Imaging. 2015;8(10):1209-1222. doi:10.1016/j.jcmg.2015.08.006
-
[15]
Diagnostic accuracy of fractional flow reserve from anatomic CT angiography
Min JK, Leipsic J, Pencina MJ, et al. Diagnostic accuracy of fractional flow reserve from anatomic CT angiography. Jama. 2012;308(12):1237-1245. doi:10.1001/2012.jama.11274
-
[16]
Coenen A, Lubbers MM, Kurata A, et al. Fractional flow reserve computed from noninvasive CT angiography data: diagnostic performance of an on-site clinician- operated computational fluid dynamics algorithm. Radiology. 2015;274(3):674-
work page 2015
-
[17]
doi:10.1148/radiol.14140992
-
[18]
Kirbas, C. Quek F. A review of vessel extraction techniques and algorithms. Comput Surv. 2004;36(2):81-121. doi:10.1145/1031120.1031121
-
[19]
A review of 3D vessel lumen segmentation techniques: Models, features and extraction schemes
Lesage D, Angelini ED, Bloch I, Funka-Lea G. A review of 3D vessel lumen segmentation techniques: Models, features and extraction schemes. Med Image Anal. 2009;13(6):819-845. doi:10.1016/j.media.2009.07.011
-
[20]
Kirişli HA, Schaap M, Metz CT, et al. Standardized evaluation framework for evaluating coronary artery stenosis detection, stenosis quantification and lumen segmentation algorithms in computed tomography angiography. Med Image Anal. 2013;17(8):859-876. doi:10.1016/j.media.2013.05.007
-
[21]
http://coronary.bigr.nl/stenoses/
Coronary Artery Stenoses Detection and Quantification Evaluation Framework. http://coronary.bigr.nl/stenoses/. 34
-
[22]
Globally optimal segmentation of interacting surfaces with geometric constraints
Li KLK, Wu XWX, Chen DZ, Sonka M. Globally optimal segmentation of interacting surfaces with geometric constraints. Proc 2004 IEEE Comput Soc Conf Comput Vis Pattern Recognition, 2004 CVPR 2004. 2004;1:0-5. doi:10.1109/CVPR.2004.1315059
-
[23]
Bayesian Segmentation of Atrium Wall Using Globally-Optimal Graph Cuts on 3D Meshes
Veni G, Fu Z, Awate SP, Whitaker RT. Bayesian Segmentation of Atrium Wall Using Globally-Optimal Graph Cuts on 3D Meshes. In: Gee JC, Sarang J, Kilian MP, Wells WM, Zöllei L, EDS. Inf Process Med Imaging. LNCS, Vol. 7917. Springer-Verlag Berlin, Heidelberg; 2013:656–667. doi: 10.1007/978-3-642- 38868-2_55
-
[24]
Lugauer F, Zhang J, Zheng Y, Hornegger J, Kelm BM. Improving accuracy in coronary lumen segmentation via explicit calcium exclusion, learning-based ray detection and surface optimization. SPIE Med Imaging. 2014;9034:90343U- 90343U-10. doi:10.1117/12.2043238
-
[25]
Precise lumen segmentation in coronary computed tomography angiography
Lugauer F, Zheng Y, Hornegger J, Kelm BM. Precise lumen segmentation in coronary computed tomography angiography. In: Menze B, Langs G, Montillo A, et al, eds. Medical Computer Vision: Algorithms for Big Data LNCS, Vol. 8848. Springer-Verlag Berlin, Heidelberg; 2014:137–147. doi:10.1007/978-3-319-13972- 2_13
-
[26]
Sato Y, Yamamoto S, Tamura S. Accurate Quantification of Small-Diameter Tubular Structures in Isotropic CT Volume Data Based on Multiscale Line Filter Responses. In: Barillot C, Haynor DR, and Hellier P, eds. Medical Image Computing and Computer-Assisted Intervention -- MICCAI 2004: 7th International Conference, LNCS, Vol. 3216. Springer International Pub...
-
[27]
Prevrhal S, Fox JC, Shepherd JA, Genant HK. Accuracy of CT-based thickness measurement of thin structures: modeling of limited spatial resolution in all three dimensions. Med Phys. 2003;30(1):1-8. doi:10.1118/1.1521940
-
[28]
Full width at half maximum as a measure of vessel diameter in computed tomography angiography
Varma JK, Subramanyan K, Durgan J. Full width at half maximum as a measure of vessel diameter in computed tomography angiography. In: Vol 5372. ; 2004:447-454. http://dx.doi.org/10.1117/12.535642
-
[29]
Freiman M, Lamash Y, Gilboa G, et al. Automatic coronary lumen segmentation with partial volume modeling improves lesions’ hemodynamic significance assessment. In: SPIE Medical Imaging. ; 2016:978403. http://dx.doi.org/10.1117/12.2209476
-
[30]
Computer- aided simple triage (CAST) for coronary CT angiography (CCTA)
Goldenberg R, Eilot D, Begelman G, Walach E, Ben-Ishai E, Peled N. Computer- aided simple triage (CAST) for coronary CT angiography (CCTA). Int J Comput Assist Radiol Surg. 2012;7(6):819-827. doi:10.1007/s11548-012-0684-7
-
[31]
Automatic segmentation, detection and quantification of coronary artery stenoses on CTA
Shahzad R, Kirişli H, Metz C, et al. Automatic segmentation, detection and quantification of coronary artery stenoses on CTA. Int J Cardiovasc Imaging. 2013:1847-1859. doi:10.1007/s10554-013-0271-1
-
[32]
Nearest neighbor pattern classification
Cover T, Hart P. Nearest neighbor pattern classification. IEEE Trans Inf Theory. 1967;13(1):21-27. doi:10.1109/TIT.1967.1053964
-
[33]
Fast Approximate Nearest Neighbors with Automatic Algorithm Configuration
Muja M, Lowe DG. Fast Approximate Nearest Neighbors with Automatic Algorithm Configuration. Int Conf Comput Vis Theory Appl (VISAPP ’09). 2009:1-10. doi:10.1.1.160.1721
work page 2009
-
[34]
Graph cuts and efficient N-D image segmentation
Boykov Y, Funka-Lea G. Graph cuts and efficient N-D image segmentation. Int J 36 Comput Vis. 2006;70(2):109-131. doi:10.1007/s11263-006-7934-5
-
[35]
Learning Patient-Specific Lumped Models for Interactive Coronary Blood Flow Simulations
Nickisch H, Lamash Y, Prevrhal S, et al. Learning Patient-Specific Lumped Models for Interactive Coronary Blood Flow Simulations. In: Navab N, Hornegger J, Wells MW, Frangi FA, eds. Medical Image Computing and Computer-Assisted Intervention -- MICCAI 2015: 18th International Conference, LNCS, Vol. 9350. Springer-Verlag Berlin, Heidelberg; 2015:433-441. do...
-
[36]
Intraspecific scaling laws of vascular trees
Huo Y, Kassab GS. Intraspecific scaling laws of vascular trees. J R Soc Interface. 2012;9(66):190-200. doi:10.1098/rsif.2011.0270
-
[37]
Workstation-Based Calculation of CTA- Based FFR for Intermediate Stenosis
Kruk M, Wardziak Ł, Demkow M, et al. Workstation-Based Calculation of CTA- Based FFR for Intermediate Stenosis. JACC Cardiovasc Imaging. 2016;9(6):690-
work page 2016
-
[38]
doi:10.1016/j.jcmg.2015.09.019
-
[39]
Delong ER, DeLong DM, Clarke-Pearson DL. Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics. 1988;44(3):837-845. doi:10.2307/2531595
-
[40]
Segmentation of the heart and great vessels in CT images using a model-based adaptation framework
Ecabert O, Peters J, Walker MJ, et al. Segmentation of the heart and great vessels in CT images using a model-based adaptation framework. Med Image Anal. 2011;15(6):863-876. doi:10.1016/j.media.2011.06.004
-
[41]
Automatic model-based segmentation of the heart in CT images
Ecabert O, Peters J, Schramm H, et al. Automatic model-based segmentation of the heart in CT images. IEEE Trans Med Imaging. 2008;27(9):1189-1202. doi:10.1109/TMI.2008.918330
-
[42]
Freiman M, Joskowicz L, Broide N, et al. Carotid vasculature modeling from patient CT angiography studies for interventional procedures simulation. Int J 37 Comput Assist Radiol Surg. 2012;7(5):799-812. doi:10.1007/s11548-012-0673-x
-
[43]
Zheng Y, Tek H, Funka-Lea G. Robust and accurate coronary artery centerline extraction in CTA by combining model-driven and data-driven approaches. In: Mori K, Sakuma I, Sato Y, Barillot C, and Navab N, eds. Medical Image Computing and Computer-Assisted Intervention -- MICCAI 2013: 16th International Conference, LNCS, Vol. 8151. Springer-Verlag Berlin, He...
-
[44]
Schaap M, Metz CT, van Walsum T, et al. Standardized evaluation methodology and reference database for evaluating coronary artery centerline extraction algorithms. Med Image Anal. 2009;13(5):701-714. doi:10.1016/j.media.2009.06.003
-
[45]
Taylor CA, Fonte TA, Min JK. Computational fluid dynamics applied to cardiac computed tomography for noninvasive quantification of fractional flow reserve: Scientific basis. J Am Coll Cardiol. 2013;61(22):2233-2241. doi:10.1016/j.jacc.2012.11.083
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