Beyond greyscale: improved detection of myocardial perfusion defects in spectral CT aortic angiography.

Abstract

A 27-year-old female presented with acute-onset left-sided radiating chest pain, dizziness, and nausea triggered by recreational cycling and aggravated by exertion. Personal and family medical history was negative for heart disease. Nicotine and cannabis abuse stood out as the only cardiovascular risk factors. ECG showed T-wave inversions in V2 and V3 and cardiac biomarkers were elevated (peak hs-troponine I 17 900 ng/L, creatine kinase 1000 U/L). Thoracoabdominal ECG-gated CT angiography was performed on a second-generation spectral CT scanner (CT 7500, Philips Healthcare, the Netherlands) to rule out aortic dissection. While conventional images (A) appeared inconspicuous, the iodine density map (B) showed markedly reduced iodine uptake of the left anterolateral and inferolateral basal to midventricular myocardium (arrowhead). Emergency coronary angiography (C) confirmed type 2 spontaneous coronary dissection (SCAD) of the mid and distal left circumflex artery and hypokinesia of the lateral wall. SCAD was treated conservatively since coronary blood flow was preserved and the patient exhibited only mild symptoms at that time. In the absence of other risk factors for SCAD such as fibromuscular dysplasia or connective tissue disorders, cannabis use stands out as a possible provoking factor in our patient. This case illustrates the value of spectral CT as it allows for on-demand multi-energy analysis of routine scans without prior selection of a dedicated protocol and can improve the detection of perfusion-related pathologies. The area of reduced iodine uptake closely matched late gadolinium enhancement on follow-up cardiac MRI (D) performed 6 weeks later.