Subjects and Data Acquisition
Subjects were participants in a study on non-invasive cardiac imaging in the vascular patient population,
and were recruited from the vascular outpatient clinic.
In total,
73 patients (76.3% males,
mean age 64.8 ± 8.1 years) could be included.
3D datasets of the heart and coronary arteries were acquired on a dual-source CT scanner (SOMATOM Definition,
Siemens,Erlangen,Germany) using a standardized contrast-enhanced cardiac scanning protocol.
Table pitch was adapted to the heart rate of the patient.
Images were reconstructed as consecutive 0.6 mm slices.
Reconstructions of the end-diastolic phase were used in this study.
Assessment of coronary artery disease
Analysis of cCTA images was performed by the attending radiologist,
with experience in cardiac CT ranging from 5 to more than 10 years.
Presence of plaque,
severity of stenosis (significant/non-significant) and plaque type (soft,
mixed,
calcified) were assessed per segment.
Segments were classified as having significant stenosis if there was ≥50% lumen diameter reduction by visual assessment.
Patients were classified as having no significant CAD,
significant CAD in a single vessel,
or significant CAD in multiple vessels.
Assessment of coronary artery geometry
Two observers assessed the 3D reconstructions of the main coronary arteries (RCA,
LCX,
LAD) using a cardiac workflow protocol.
The vessel of interest was selected manually to initialize the automatic centerline extraction and to perform the,
centerline-based,
curvature and tortuosity measurements (Fig 1).
Curved multi-planar reconstructions based on the centerline were used for the vessel analysis.
Segments were identified using the 15-segment AHA classification model.
Only segments with an average diameter of more than 1.5 mm were included.
Each segment was marked (Fig 2) manually followed by automatic curvature and tortuosity measurements on segment level (Fig 2.a) and for the total vessel (Fig 2.b).
Statistics
Associations between the vessel geometry and plaque type and significant stenosis were assessed by generalized estimating equations using two-sided statistical tests.
Comparisons were made per segment and per artery.
The curvature and tortuosity of the patients were grouped based on the plaque type and presence of stenosis and the comparison of these groups made on segment and artery level.