CCTA MapCCTA Glossary Español← Back to the map

CCTA Glossary: coronary CT angiography terms

David F. Cuevas Cueto, MD · Updated September 27, 2026 · Sources: SCCT 2026 and CAD-RADS 2.0

Coronary CT angiography according to SCCT 2026 and CAD-RADS 2.0: definitions, how they are applied, and how they look on the map.

★SCCT 2026 vs 2014Eight reporting changes, each with a quote from both documentsNew1Anatomy and nomenclatureSCCT segments, boundaries, dominance and ramus intermedius13 terms2Plaque and high-risk plaquePlaque types, high-risk features, SIS and plaque burden11 terms3StenosisDiameter stenosis, reference diameter, grading scale and total occlusion8 terms4Image quality and artifactsStudy quality, nonevaluable segments and artifacts that mimic disease8 terms5CAD-RADS 2.0 and ischemiaCategories 0–5 and N, modifier order and the I modifier10 terms6Stents and graftsRestenosis, grafts, bypassed native segments and modifiers S and G10 terms7Nonatherosclerotic findingsMyocardial bridging, anomalous origin, aneurysm and modifier E8 terms

This glossary gathers the terms you need to read a coronary CT angiogram and to use the cctamap map: segment anatomy, plaque, stenosis, image quality, and the CAD-RADS 2.0 categories and modifiers. Each term has its definition, how it is applied at the workstation, the most common pitfall and how it appears on the map, with an example case that opens in one click.

Definitions follow the 2026 SCCT consensus and CAD-RADS 2.0, with the table and page cited for each term. The reference for the full cardiac CT terminology is the SCCT standardized terminology document, updated in 2023. This is academic material and does not replace guidelines or clinical judgment.

A–Z index

Acute marginal branch AM · no number
The acute marginal arises from the RCA between the end of the mid RCA and the acute margin of the heart.
Agatston score CAC
For each coronary lesion, the area of calcium above the 130 HU threshold is multiplied by a factor of 1 to 4 according to its peak attenuation.
Anomalous origin of a coronary artery AAOCA · ALCAPA · ARCAPA
A coronary artery has an anomalous origin when it arises outside its usual site.
Arterial graft (internal mammary and radial artery) LIMA
An arterial graft uses one of the patient's arteries as the conduit.
Assignment of disease at segment intersections and bifurcations
When a lesion lies at the junction of two segments, including bifurcations, it is assigned to the preceding segment, the more proximal one in the direction of flow.
Beam-hardening artifact
Metal, calcium and dense contrast preferentially absorb low-energy photons.
Blooming artifact
Partial volume averaging within each voxel blurs the interface between the lumen and calcium or a stent.
Bypassed native segment
A native segment is bypassed when it lies proximal to the distal anastomosis of a graft.
CAD-RADS 0 versus CAD-RADS 1
A study is CAD-RADS 0 only if there is no plaque and no stenosis.
CAD-RADS 2 and CAD-RADS 3
In CAD-RADS 2 the maximal stenosis is mild (25–49 %) and disease is nonobstructive.
CAD-RADS 4A versus 4B 4A · 4B
CAD-RADS 4A is severe stenosis (70–99 %) in one or two vessels.
CAD-RADS 5 (total occlusion)
CAD-RADS 5 indicates at least one total occlusion (100 %).
CAD-RADS coding order and modifiers P · N · HRP · I · S · G · E
The CAD-RADS 2.0 code follows the order stenosis, plaque burden and modifiers, separated by slashes.
CAD-RADS in stable chest pain
CAD-RADS 2.0 pairs each category with suggested management for the patient with stable chest pain.
Calcified plaque
In calcified plaque, most of the plaque volume has higher attenuation than the opacified lumen.
Coronary artery aneurysm and ectasia
A coronary aneurysm is a segment with a diameter more than 1.5 times that of the adjacent normal segment, involving less than 50 % of the vessel length.
Coronary dominance (right, left and co-dominant)
The origin of the posterior descending artery defines dominance.
Course of an anomalous coronary artery
The course indicates where the anomalous artery crosses the base of the heart.
Diameter stenosis %DS
Diameter stenosis is the percent reduction in luminal diameter at the narrowest point relative to a normal reference segment.
Evaluable and non-evaluable stent
A stent is evaluable when its lumen is seen clearly enough to grade restenosis.
First and second diagonal branches D1 (9) · D2 (10)
D1 and D2 are the two largest diagonal branches traversing the anterolateral wall of the left ventricle.
First and second obtuse marginal branches OM1 (12) · OM2 (14)
The obtuse marginals arise from the LCx and traverse the lateral wall of the left ventricle.
Graft stenosis and graft occlusion
Graft stenosis is graded like native-vessel stenosis and is located at an anastomosis or in the graft body.
High-risk anatomy of an anomalous coronary artery
An interarterial course, an intramural segment, a slit-like orifice, an acute take-off angle, proximal narrowing and a high origin are considered high risk because they are associated with ischemia.
High-risk plaque HRP
A plaque is high-risk if it clearly shows at least two of four features (low attenuation, positive remodeling, spotty calcification and the napkin-ring sign).
Image noise
When photon counts are low, the image acquires a grainy texture with random bright and dark streaks.
In-stent restenosis ISR
In-stent restenosis is narrowing of the lumen inside the stent or at its edges.
In-stent total occlusion
In-stent total occlusion is present when a segment of the stent lumen shows no contrast.
Intramural course
The intramural segment is the proximal portion of the anomalous artery that runs within the aortic wall before separating from it.
Ischemia modifier with CT-derived fractional flow reserve I+ · I± · I−
With CT-FFR, the I modifier is assigned from the lesion-specific value.
Ischemia modifier with stress CT perfusion CTP
On CT perfusion, a defect that is reversible or larger at stress than at rest is I+.
Left main coronary artery LM · segment 5
The left main is segment 5.
Low-attenuation plaque
A non-calcified plaque has low attenuation, one of the high-risk features, when its internal attenuation is less than 30 HU.
Minimum assessable vessel diameter ≥1.5 mm
The guideline asks for all branches with a diameter of 1.5 mm or more to be assessed when the scan is of good quality, and those of 2.0 mm or more when it is of standard quality.
Misalignment (stair-step) artifact
Misalignment is an abrupt offset of structures at the boundary between slabs acquired in different heartbeats, usually caused by an irregular rhythm or incorrect ECG gating.
Modifier E (exceptions) E
Modifier E flags a nonatherosclerotic coronary finding.
Modifier G (graft) G
G indicates the presence of at least one coronary artery bypass graft.
Modifier S (stent) S
S indicates the presence of at least one coronary stent anywhere in the coronary tree.
Motion artifact
Cardiac, respiratory or body motion during acquisition blurs the vessel contours.
Myocardial bridge depth, length and systolic compression
SCCT 2026 classifies the bridge by depth and length.
Myocardial bridging
A segment of an epicardial artery runs through a tunnel within the myocardium, and the muscle band covering it is the bridge.
Napkin-ring sign
The napkin-ring sign is a high-risk feature seen on the cross-section of a non-calcified plaque: a low-attenuation center, apparently in contact with the lumen, surrounded by a ring of higher attenuation.
Non-calcified plaque
Non-calcified plaque has lower attenuation than the opacified lumen.
Non-diagnostic (N) category and modifier N
N flags segments larger than 1.5 mm that cannot be interpreted with confidence.
Non-interpretable (non-diagnostic) segment
A segment 1.5 mm in diameter or larger is non-interpretable (nonevaluable) when an artifact prevents confident interpretation.
Obstructive and nonobstructive stenosis ≥50 % · ≥70 %
A stenosis of 50 % or more is called obstructive, and one below 50 % nonobstructive.
Overall image quality
Because there is no established standard, SCCT 2026 recommends grading the whole study on a visual scale, for example excellent, good, average, fair, poor or non-diagnostic.
Partially calcified plaque
It combines a calcified and a non-calcified component.
Per-patient CAD-RADS category CAD-RADS
CAD-RADS 2.0 assigns a single category to each patient.
Plaque burden (P1–P4) P1–P4
Plaque burden is the amount of coronary plaque, regardless of stenosis.
Positive remodeling
Positive remodeling is present when the outer vessel diameter at the plaque is more than 10 % larger than the reference diameter (remodeling index greater than 1.1).
Proximal and distal anastomoses, and distal runoff
The proximal anastomosis joins the graft to its inflow vessel, and the distal anastomosis joins it to the recipient coronary artery.
Proximal and distal left circumflex artery LCx · segments 11 and 13
The proximal LCx runs from the end of the LM to the origin of OM1.
Proximal, mid and distal left anterior descending artery LAD · segments 6, 7 and 8
The proximal LAD runs from the end of the LM to the first large septal branch.
Proximal, mid and distal right coronary artery RCA · segments 1, 2 and 3
The proximal RCA runs from the ostium to one-half the distance to the acute margin of the right ventricle.
Ramus intermedius RI · segment 17
The ramus intermedius arises directly from the left main, between the LAD and the LCx, when the left main trifurcates instead of bifurcating.
Reference luminal diameter RLD
The reference luminal diameter is measured in the lumen of a normal segment near the stenosis, proximal or distal, or taken as the average of both.
Reporting a coronary stenosis
Each stenosis is described by its anatomical location, the type of plaque causing it, and its grade as a term with its range.
Right and left posterior descending artery; right and left posterolateral branch R-PDA (4) · L-PDA (15) · R-PLB (16) · L-PLB (18)
The posterior descending artery (R-PDA from the RCA, L-PDA from the LCx) runs in the posterior interventricular groove.
Saphenous vein graft SVG
A vein graft is a segment of the great saphenous vein used as a free graft from the ascending aorta to the coronary artery.
SCCT coronary artery segmentation model (18 segments)
The SCCT adapted the AHA segment model for interpreting coronary CT angiography.
Segment involvement score SIS
The SIS counts coronary segments with plaque, regardless of plaque composition or stenosis grade.
Serial stenoses and diffuse disease
Several stenoses in the same vessel, separated by normal lumen, form serial or multifocal disease.
Spotty calcification
Spotty calcification is a calcium deposit less than 3 mm in diameter within a plaque.
Stenosis grading scale 0–5
SCCT 2026 and CAD-RADS 2.0 divide diameter stenosis into six grades: 0 %, minimal (1–24 %), mild (25–49 %), moderate (50–69 %), severe (70–99 %) and total occlusion (100 %).
Suboptimal contrast enhancement
Enhancement is suboptimal when contrast opacifies the lumen poorly because of body size, slow circulation, injection technique or extravasation.
Total occlusion 100 %
A total occlusion is a coronary segment with no luminal opacification, equivalent to 100 % stenosis.
Visual estimation and quantitative measurement
In visual estimation, the reader assigns the stenosis range by comparing the lumen with the reference by eye.

References

  1. Rajiah PS, Alkadhi H, Andreini D, Bullock-Palmer RP, Chinnaiyan K, Chow B, et al. Interpretation and reporting of coronary computed tomographic angiography (2026 update): an expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT). J Cardiovasc Comput Tomogr. 2026. In press. doi:10.1016/j.jcct.2026.08.014 Cited pages refer to the journal pre-proof PDF.
  2. Cury RC, Leipsic J, Abbara S, Achenbach S, Berman D, Bittencourt M, et al. CAD-RADS 2.0 - 2022 Coronary Artery Disease-Reporting and Data System: an expert consensus document of the SCCT, ACC, ACR and NASCI. J Cardiovasc Comput Tomogr. 2022;16(6):536-57. doi:10.1016/j.jcct.2022.07.002
  3. Koweek L, Achenbach S, Berman DS, Carr JJ, Cury RC, Ghoshhajra B, et al. Standardized medical terminology for cardiac computed tomography 2023 update: an expert consensus document of the SCCT, AAPM, ACR, NASCI and RSNA. J Cardiovasc Comput Tomogr. 2023;17(5):345-54. doi:10.1016/j.jcct.2023.06.002
  4. Narula J, Chandrashekhar Y, Ahmadi A, Abbara S, Berman DS, Blankstein R, et al. SCCT 2021 expert consensus document on coronary computed tomographic angiography: a report of the Society of Cardiovascular Computed Tomography. J Cardiovasc Comput Tomogr. 2021;15(3):192-217. doi:10.1016/j.jcct.2020.11.001
  5. Neves PO, Andrade J, Monção H. Coronary artery calcium score: current status. Radiol Bras. 2017;50(3):182-9.
  6. Tamburino C, Tomasello SD, Capodanno D, Di Salvo ME, Marzà F, Galassi AR. Long-term follow-up after drug eluting stent implantation in left main trifurcations. EuroIntervention. 2009;5(4):432-7. doi:10.4244/eijv5i4a68
  7. Kovacevic M, Burzotta F, Elharty S, Besis G, Aurigemma C, Romagnoli E, et al. Left main trifurcation and its percutaneous treatment: what is known so far? Circ Cardiovasc Interv. 2021;14(3):e009872. doi:10.1161/CIRCINTERVENTIONS.120.009872
  8. Kim C, Park CH, Lee BY, et al. 2024 consensus statement on coronary stenosis and plaque evaluation in CT angiography from the Asian Society of Cardiovascular Imaging-Practical Tutorial (ASCI-PT). Korean J Radiol. 2024;25(4):331-42. doi:10.3348/kjr.2024.0112

Sources for the “Other sources” notes

  1. Sianos G, Morel MA, Kappetein AP, et al. The SYNTAX Score: an angiographic tool grading the complexity of coronary artery disease. EuroIntervention. 2005;1(2):219-27.
  2. Leipsic J, Abbara S, Achenbach S, Cury R, Earls JP, Mancini GBJ, et al. SCCT guidelines for the interpretation and reporting of coronary CT angiography: a report of the Society of Cardiovascular Computed Tomography Guidelines Committee. J Cardiovasc Comput Tomogr. 2014;8(5):342-58. doi:10.1016/j.jcct.2014.07.003
  3. Dąbrowski EJ, Kożuch M, Dobrzycki S. Left main coronary artery disease: current management and future perspectives. J Clin Med. 2022;11(19):5745. doi:10.3390/jcm11195745
  4. Halpern EJ. Clinical Cardiac CT: Anatomy and Function. 2nd ed. New York: Thieme; 2011.
  5. Medina A, Suárez de Lezo J, Pan M. Una clasificación simple de las lesiones coronarias en bifurcación. Rev Esp Cardiol. 2006;59(2):183. doi:10.1157/13084649
  6. IMAIOS e-Anatomy. Right marginal branch of the right coronary artery (ramus marginalis dexter).
  7. Cury RC, Abbara S, Achenbach S, et al. CAD-RADS: Coronary Artery Disease – Reporting and Data System. J Cardiovasc Comput Tomogr. 2016;10(4):269-81. doi:10.1016/j.jcct.2016.04.005
  8. Nieman K, García-García HM, Hideo-Kajita A, et al. Standards for quantitative assessments by coronary computed tomography angiography (CCTA): an expert consensus document of the SCCT. J Cardiovasc Comput Tomogr. 2024;18(5):429-43. doi:10.1016/j.jcct.2024.05.232
  9. Williams MC, Moss AJ, Dweck M, et al. Coronary artery plaque characteristics associated with adverse outcomes in the SCOT-HEART study. J Am Coll Cardiol. 2019;73(3):291-301. doi:10.1016/j.jacc.2018.10.066
  10. van Rosendael SE, Shiyovich A, Cardoso RN, Souza Freire CV, van Rosendael AR, Lin FY, et al. The role of cardiac computed tomography angiography in risk stratification for coronary artery disease. J Soc Cardiovasc Angiogr Interv. 2024;3(11):102230. doi:10.1016/j.jscai.2024.102230
  11. Yang S, Lee JM, Hoshino M, Murai T, Choi KH, Hwang D, et al. Prognostic implications of comprehensive whole vessel plaque quantification using coronary computed tomography angiography. JACC Asia. 2021;1(1):37-48. doi:10.1016/j.jacasi.2021.05.003
  12. Pozo E, Agudo-Quilez P, Rojas-González A, Alvarado T, Olivera MJ, Jiménez-Borreguero LJ, et al. Noninvasive diagnosis of vulnerable coronary plaque. World J Cardiol. 2016;8(9):520-33. doi:10.4330/wjc.v8.i9.520
  13. Bittencourt MS, Hulten E, Ghoshhajra B, et al. Prognostic value of nonobstructive and obstructive coronary artery disease detected by coronary computed tomography angiography to identify cardiovascular events. Circ Cardiovasc Imaging. 2014;7(2):282-91. doi:10.1161/CIRCIMAGING.113.001047
  14. Hecht HS, Blaha MJ, Kazerooni EA, et al. CAC-DRS: Coronary Artery Calcium Data and Reporting System. An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT). J Cardiovasc Comput Tomogr. 2018;12(3):185-91. doi:10.1016/j.jcct.2018.03.008
  15. Obisesan OH, Osei AD, Uddin SMI, Dzaye O, Blaha MJ. An update on coronary artery calcium interpretation at chest and cardiac CT. Radiol Cardiothorac Imaging. 2021;3(1):e200484. doi:10.1148/ryct.2021200484
  16. Kim C, Park CH, Lee BY, et al. 2024 consensus statement on coronary stenosis and plaque evaluation in CT angiography from the Asian Society of Cardiovascular Imaging-Practical Tutorial (ASCI-PT). Korean J Radiol. 2024;25(4):331-42. doi:10.3348/kjr.2024.0112
  17. Raff GL, Abidov A, Achenbach S, et al. SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography. J Cardiovasc Comput Tomogr. 2009;3(2):122-36. doi:10.1016/j.jcct.2009.01.001
  18. Galassi AR, Vadalà G, Werner GS, et al. Evaluation and management of patients with coronary chronic total occlusions considered for revascularisation. A clinical consensus statement of the European Association of Percutaneous Cardiovascular Interventions (EAPCI) of the ESC, the European Association of Cardiovascular Imaging (EACVI) of the ESC, and the ESC Working Group on Cardiovascular Surgery. EuroIntervention. 2024;20(3):e174-84. doi:10.4244/EIJ-D-23-00749
  19. Rajiah PS, Alkadhi H, Andreini D, et al. Interpretation and reporting of coronary computed tomographic angiography (2026 update): an expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT). J Cardiovasc Comput Tomogr. 2026 (pre-proof). doi:10.1016/j.jcct.2026.08.014
  20. Lawton JS, Tamis-Holland JE, Bangalore S, et al. 2021 ACC/AHA/SCAI guideline for coronary artery revascularization: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. J Am Coll Cardiol. 2022;79(2):e21-e129. doi:10.1016/j.jacc.2021.09.006
  21. Koweek L, Achenbach S, Berman DS, et al. Standardized medical terminology for cardiac computed tomography 2023 update: an expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT), American Association of Physicists in Medicine (AAPM), American College of Radiology (ACR), North American Society for Cardiovascular Imaging (NASCI), and Radiological Society of North America (RSNA). Radiol Cardiothorac Imaging. 2023;5(4):e230167. doi:10.1148/ryct.230167
  22. Abbara S, Blanke P, Maroules CD, et al. SCCT guidelines for the performance and acquisition of coronary computed tomographic angiography: a report of the Society of Cardiovascular Computed Tomography Guidelines Committee. Endorsed by the North American Society for Cardiovascular Imaging (NASCI). J Cardiovasc Comput Tomogr. 2016;10(6):435-49. doi:10.1016/j.jcct.2016.10.002
  23. Galassi AR, Werner GS, Boukhris M, et al. Percutaneous recanalisation of chronic total occlusions: 2019 consensus document from the EuroCTO Club. EuroIntervention. 2019;15(2):198-208. doi:10.4244/EIJ-D-18-00826
  24. Tonino PA, De Bruyne B, Pijls NH, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention. N Engl J Med. 2009;360(3):213-24. doi:10.1056/NEJMoa0807611
  25. Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2021;144(22):e368-e454. doi:10.1161/CIR.0000000000001029
  26. Taylor AJ, Cerqueira M, Hodgson JM, et al. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 appropriate use criteria for cardiac computed tomography. J Am Coll Cardiol. 2010;56(22):1864-94. doi:10.1016/j.jacc.2010.07.005
  27. Mehran R, Dangas G, Abizaid AS, et al. Angiographic patterns of in-stent restenosis: classification and implications for long-term outcome. Circulation. 1999;100(18):1872-8. doi:10.1161/01.cir.100.18.1872
  28. IMAIOS. Internal thoracic artery (Arteria thoracica interna). e-Anatomy [Internet]. Montpellier: IMAIOS [cited 2026 Sep 26]. Available from: https://www.imaios.com/en/e-anatomy/anatomical-structures/internal-thoracic-artery-1553667652
  29. Taggart DP, Altman DG, Gray AM, et al. Randomized Trial of Bilateral versus Single Internal-Thoracic-Artery Grafts. N Engl J Med. 2016;375(26):2540-9. doi:10.1056/NEJMoa1610021
  30. Chen SS, Prasad SK. Long saphenous vein and its anatomical variations. Australas J Ultrasound Med. 2009;12(1):28-31. doi:10.1002/j.2205-0140.2009.tb00004.x
  31. Tector AJ, Schmahl TM, Canino VR, et al. The role of the sequential internal mammary artery graft in coronary surgery. Circulation. 1984;70(3 Pt 2):I222-5.
  32. FitzGibbon GM, Burton JR, Leach AJ. Coronary bypass graft fate: angiographic grading of 1400 consecutive grafts early after operation and of 1132 after one year. Circulation. 1978;57(6):1070-4. doi:10.1161/01.cir.57.6.1070
  33. Noble J, Bourassa MG, Petitclerc R, et al. Myocardial bridging and milking effect of the left anterior descending coronary artery: normal variant or obstruction? Am J Cardiol. 1976;37(7):993-9. doi:10.1016/0002-9149(76)90414-8
  34. Xu T, You W, Wu Z, et al. Retrospective analysis of OCT on MB characteristics and 1-year follow-up of the ISR incidence after the DES implantation in patients with MB. Sci Rep. 2022;12(1):534. doi:10.1038/s41598-021-04579-9
  35. Narula J, Chandrashekhar Y, Ahmadi A, et al. SCCT 2021 expert consensus document on coronary computed tomographic angiography: a report of the Society of Cardiovascular Computed Tomography. J Cardiovasc Comput Tomogr. 2021;15(3):192-217. doi:10.1016/j.jcct.2020.11.001
  36. Baumgartner H, De Backer J, Babu-Narayan SV, et al. 2020 ESC Guidelines for the management of adult congenital heart disease. Eur Heart J. 2021;42(6):563-645. doi:10.1093/eurheartj/ehaa554
  37. Genoud A, Portugal I, Murith N, et al. Coronary artery anomalies revisited: description of the types, pathophysiology and treatment options based on latest guidelines. J Clin Med. 2026;15(13):4959. doi:10.3390/jcm15134959
  38. Evangelista M, Ferrero P, D'Aiello AF, et al. Coronary artery anomalies: what are they? when to suspect? how to treat?—a narrative review. Transl Pediatr. 2024;13(7):1242-57. doi:10.21037/tp-24-30
  39. Karatoprak NB, Karatoprak S, Şahin Ö. Coronary artery origin anomalies on coronary CT angiography: a single-center tertiary-care cohort. J Clin Pract Res. 2026;48(2):137-44. doi:10.14744/cpr.2026.27967
  40. Ganga KP, Goyal A, Ojha V, et al. Prevalence rates of congenital coronary anomalies and coronary variations in adult Indian population using dual-source computed tomography coronary angiography: analysis of regional distribution of coronary anomalies and the need for standardized reporting formats. Indian J Radiol Imaging. 2021;31(1):138-49. doi:10.1055/s-0041-1730135