Fig 1.
Four types of calcified plaque.
Type I: ratio of calcified plaque volume to vessel circumference (RVTC) ≤ 25%; type II: RVTC 26–50%; type III: RVTC 51–75%; and type IV: RVTC 76–100%.
Table 1.
Patient characteristics.
Fig 2.
A 67-year old male presenting with typical chest pain for about 2 months.
(a) Curved multiplanar reconstruction, (b, c, d, e) axial images and (f) conventional coronal angiography of right coronary artery in a 68-year-old patient. The calcified plaque (arrow) in segment 1 was classified as type I according to its corresponding axial image (b), the stenosis severity of type I calcified plaque was about 8% that was evaluated by CCTA (arrow), and CAG shows no significant stenosis (arrow); Another calcified plaque (curved arrow) in segment 1 was classified as type II according to its corresponding axial image (c), the stenotic severity of type II calcified plaque was about 37% evaluated by CCTA (curved arrow), and the CAG shows no significant stenosis (curved arrow); The calcified plaque (arrow head) in segment 3 was classified as type III according to its corresponding axial image (d), the stenotic severity of type III calcified plaque was about 68% evaluated by CCTA (arrow head), while the CAG shows mild significant stenosis (< 50%) (arrow head); Another calcified plaque (asterisk) in segment 3 was classified as type IV according to its corresponding axial image (e), the stenotic severity of type IV calcified plaque was about 82% evaluated by CCTA (asterisk), while the CAG show no significant stenosis (asterisk).
Fig 3.
A chart of diagnostic accuracy of CCTA for evaluating severity of stenosis in different type of calcified plaque.
Sensitivity and NPV showed a minor variation in type I to IV calcified plaques. While specificity decreased from 99.8% (type I) to 67.9% (type IV), PPV decreased from 95.7% (type I) to 56.2% (type IV), and accuracy decreased from 99.6% (type II) to 76.8% (type IV).
Table 2.
Diagnostic accuracy of CCTA for evaluating stenosis severity of calcified plaque.
Fig 4.
Receive-operating characteristics (ROC) curves illustrate the CCTA ability of evaluating significant stenosis due to different types of calcified plaque.
The areas under the ROC curves (AUCs) are 0.983, 0.976, 0.877 and 0.829 respectively for type I to IV calcified plaques.