64-multidetector computed tomographic angiography of the canine coronary arteries

Abstract

Canine coronary artery angiography (CTA) was performed in four anesthetized healthy dogs using 64-multidetector computed tomography. Esmolol, a β-1 adrenergic receptor antagonist, and sodium nitroprusside, an arteriolar and venous dilator, were administered to enhance visualization of the coronary arteries by reducing heart rate and creating vasodilation. The left main coronary artery with its three main branches and the right coronary artery were visualized and subdivided in 13 segments for evaluation. Optimal reconstruction interval, expressed as percentage of the R-to-R interval, was determined at 5% in 2.9%, 35% in 1%, 75% in 21.2%, 85% in 43.3%, and 95% in 31.7% of the segments. Overall image quality was good in 41.3% of the segments and excellent in 14.4%. There was blur in 98.1%, motion in 17.3%, and stair step in 6.7% of the evaluated segments, but these artifacts did not interfere with anatomic depiction of the arteries. Cross-sectional anatomy of the coronary arteries as evaluated from the coronary CTA agreed well with gross anatomic evaluation and published information. The use of esmolol did not lead to the target heart rate of 60-65 beats/min. Nitroprusside had no significant effect on visualized length or diameter of the coronary artery branches. Coronary CTA is useful for the anatomic depiction of coronary artery branches in the dog.

Fig. 1

For retrospective EKG gating the reconstruction interval, also called reconstruction window, is expressed as the percentage of the R-to-R interval.

Fig. 2

Transverse images of the paraconal interventricular branch of the left coronary artery (LPIV), reconstructed at 95% (A) and 5% (B) of the R-to-R interval. At 5% reconstruction interval, motion artifact causes the false display of two vessels and blur, whereas only mild blur is evident using the 95% reconstruction interval.

Fig. 3

Variation of the branching pattern of the left coronary artery in three dogs displayed as thick-slice reconstruction (6.48 mm): The left circumflex (LCX), left interventricular paraconalis (LIVP) and left septal (LS) branch arise from the short coronary artery as separate branches (A), but when the main left coronary artery is very short, this may appear as direct branching off the LCX and LIVP off the aorta (B). Variation of the branching pattern with two separate branches of the LS was seen in one dog (C).

Fig. 4

Circumflex branch of the left coronary artery (LCX): Curved multiplanar reconstruction (A, B) and transverse images (C, D) reconstructed at 85% (A, C) and 65% (B, D) of the R-to-R interval. Reconstruction at the suboptimal reconstruction interval leads to stair-step artifact in the plane of the artery (B) and motion (D).Mild blur is evident even at optimal reconstruction interval due to limits in resolution, but this does not impact the anatomic localization of the coronary artery branch.

Fig. 5

Curved multiplanar reconstruction at the level of the right coronary artery (RCA) reconstructed at 75% (A) and 25% (B) of the R-to-R interval. Reconstruction at the suboptimal interval at 25% causes increased blur and introduces stair-step artifact. Stair-step artifact, however, is not in the image plane of the right coronary artery and does not interfere with anatomic depiction of this vessel.

Fig. 6

Motion artifact in the right coronary artery on transverse plane reconstruction is increased from 75% (A) to 95% (B) reconstruction interval of the R-to-R interval. Motion artifact can be observed when the vessel runs perpendicular to the imaging plane.