Visualization of coronary arterial wall based on maximum intensity fusion of whole-heart MR angiograms and water suppression SPIR 3D T1 TFE images

Abstract

Purpose: We estimated the coronary artery wall using maximum intensity fusion (MIF) of whole-heart magnetic resonance (MR) angiography (WHCA) and water suppressionspectral presaturation with inversion recovery (WS-SPIR) 3D T1-weighted turbo field echo (3DT1 TFE). Methods: We created a phantom using a wall of plastic bottles varied with plastic tapes measuring 0.4 to 3.0 mm thick (0-14 sheets) by vernier caliper and compared widths with those on profile curves. In 3 patients, to clarify the capacity to visualize the coronary wall in vulnerable plaque, we acquired WS-SPIR 3D T1 TFE and WS-spectral attenuation with inversion recovery (SPAIR) (inversion time [TI] 400 ms) 3D T1 TFE images of carotid vulnerable plaque; also termed "lipid-rich plaque," vulnerable plaque is considered to be visualized in high intensity. We utilized the same geometric parameters and rest period on WHCA as for WS-SPIR 3D T1 TFE. We obtained MIF of WHCA and WS-SPIR 3D T1 TFE and measured thickness of the right coronary artery (RCA) wall on the profile curve in 18 cases. Results: The widths of the dip of the lower third of the bottom to head on the profile curve were consistent with actual measurement at 1-2 mm, the usual coronary artery wall thickness. Carotid plaques of high intensity by T1-weighted black-blood (T1BB) and T2- weighted BB (T2BB) methods showed high intensity on WS-SPAIR (TI 400 ms) 3D T1 TFE and low intensity on WS-SPIR 3D T1 TFE. With or without vulnerable plaque in the coronary artery wall, MIF of WHCA and WS-SPIR 3D T1 TFE reflected the coronary artery wall. We obtained bands of low intensity in MIF between epicardial fat ofWS-SPIR 3D T1 TFE and coronary artery lumen of WHCA all but mid RCA in all 18 cases. We were unable to detect mid RCA in 5 cases. The outline of the obstructed mid RCA in 1 case was clear in WS-SPIR 3D T1 TFE. The higher velocity of RCA movement caused blurring in another 4 cases in both WHCA and WS-SPIR 3D T1 TFE. Those wall thickness of proximal or mid RCA averaged 1.3±0.2 mm. Conclusion: Bands of low intensity between epicardial fat and coronary artery lumen on MIF of WHCA and WS-SPIR 3D T1 TFE can reflect the coronary artery wall.