Automated coronary artery tree extraction in coronary CT angiography using a multiscale enhancement and dynamic balloon tracking (MSCAR-DBT) method

Schematic diagram of our prototype coronary artery extraction algorithm using multiscale coronary artery response (MSCAR) segmentation and 3D dynamic balloon tracking (DBT), referred to as the MSCAR-DBT method.

Seventeen major coronary arterial segments [28] that are considered clinically significant. (1) Proximal RCA, (2) mid RCA, (3) distal RCA, (4) right posterior descending (RPD) artery, (5) main LCA, (6) Proximal left anterior descending (LAD), (7) Mid LAD, (8) apical LAD, (9) first diagonal, (10) second diagonal, (11) proximal left circumflex (LCx) artery, (12) first obtuse marginal (OM1), (13) distal, LCx, (14) second obtuse marginal (OM2), (15) posterior descending (PD), (16) posterior lateral branch (PLB), and (17) ramus intermedius segment.

The setting of visual assessment of automated segmentation and tracking of coronary arteries. (a) The PC with GUI displays the tracked coronary arteries rendered in 3D volume by our MSCAR-DBT method. (b), (c) the GE workstation displays the volume rendering of the coronary arteries obtained by the GE coronary analysis software, and the original cCTA scan.

An example of coronary arterial trees extracted by our MSCAR-DBT method. Left: the computer tracked coronary arteries rendered in 3D volume. Right: the computer tracked coronary arteries superimposed on the heart.

An example of the left and right coronary artery trees extracted by our MSCAR-DBT method (top row) and GE software (bottom row). The open white arrows point to four FNs in LCA and four FNs in RCA by GE method. The white arrows point to one FPs and two FPs by GE method and our MSCAR-DBT method, respectively. There is no FN by our method in this case.

Examples of left coronary artery trees extracted by our MSCAR-DBT method (top row) and GE software (bottom row) for two cases (left and right column). The open white arrows point to two FNs by the GE software but tracked by our MSCAR-DBT method for one case (left column) and three FNs by the GE software for another case (right column). There is no FN or FP by our MSCAR-DBT method and no FP by the GE software for both coronary trees.

An example of left and right coronary artery tree extracted by our MSCAR-DBT method (top row) and GE software (bottom row). The RCA and LCA are shown in left column and right column, respectively. One segment in RCA and 3 segments in LCA (pointed by open white arrows) were missed by both methods. These FN segments (darker vessels in top rows) were manually tracked by a radiologist to show the missing parts.

An example of coronary artery tree extracted by MSCAR-DBT method (left) and GE software (right). A long arterial segment in RCA (white arrowhead) not tracked by the GE software, was not counted as an FN for the GE software nor as FP for our MSCAR-DBT method, because it is not one of the 17 coronary arterial segments that are considered clinically significant. The LCA of this case is also shown in left column of Fig. 6.

An example of the counting of FPs for coronary artery tree extracted by our MSCAR-DBT method (top row) and the GE software (bottom row). A large connected component composing of abdominal vessels was visually separated into two FPs by radiologists, in term of their location, at the left and right side of the heart (white arrows). The two venous segments (white arrows in right column) were counted as two FPs for both methods.

An example shows a seed point (white dot pointed by white curved arrow in top right image) was manually input to RCA due to the failure of the GE software in identifying the seed point, the corresponding seed region (black circle) is shown in the original cCTA scan (bottom left). The calcified plaques (white circle in bottom right image) in the LAD caused a gap (white arrowhead) both in the coronary artery tree extracted by our MSCAR-DBT method (top left) and the GE software (top right).

An example of a failure in the tracking of the RCA due to the motion blur artifacts for both our MSCAR-DBT method (top left) and the GE software (top right). The FN segment (darker vessels pointed by open white arrow) was manually tracked by a radiologist to show the missing part. Two axial view images separated by 8 slices (bottom row) show the short starting vessel segment without motion (black circle, bottom left) that was extracted (white arrowhead) by our method, and the later segment with motion (black circle, bottom right) that failed to be tracked by either our method or the GE software.