IQon Spectral CT in Traumatic LAD Plaque Rupture

A middle-aged male presented to the emergency department following a high-speed motor vehicle collision. The man was conscious and communicating with the staff. A routine trauma scan was performed with the IQon Spectral CT scanner (Philips, The Netherlands).

Conventional computed tomography (CT) images indicated a subtle splenic laceration. A color iodine map was acquired with the IQon and superimposed over multiple levels of monoenergetic images. The iodine brightened at 40 kV on the monoenergetic reconstruction, clearly showing the splenic laceration was more extensive than suggested by the conventional CT images. The images indicated a splenic laceration on the posterior aspect of the spleen.

Upon further evaluation, conventional images of the patient’s heart appeared normal, yet the iodine map at 40 kV reconstruction again indicated otherwise. Although the septum and lateral wall demonstrated good iodine uptake, a focal, sharply marginated area of absent iodine uptake appeared on the anterior wall. Further magnification of this region of interest of the septum and anterior wall, where no perfusion was seen, revealed a difference in iodine uptake and density – 74 Hounsfield units (HU) versus 54 HU.

Small spectral curves in the perfused septum showed that the spectral curve increased as (monoenergetic/energy decreased. In the non-perfused anterior wall, the spectral curve remained flat, indicating no iodine uptake and suggesting a myocardial infarction.

Because of the splenic laceration, an echocardiogram was performed, showing a focal wall-motion abnormality in the anterior wall of the heart. The patient underwent a conventional catheter angiogram, which detected a focal, severe stenosis in the mid-left anterior descending artery (LAD). We diagnosed a traumatic plaque rupture in the LAD, which resulted in an acute myocardial infarction.

This case shows the tremendous advantage of using spectral CT to defect perfusion defects in the heart that cannot otherwise be seen.