Discrimination between acute and chronic dissection of the aorta using [18F]-Fluordesoxyglucose PET/CT

Objectives Aortic dissection is a frequently fatal medical emergency. The discrimination between acute and chronic dissections is essential for the decision to perform surgery. Therefore, it would be of clinical interest to develop imaging tools to determine the age of dissections of the aorta which is so far not possible by morphological imaging.

Methods A group of 18 consecutive patients with acute chest pain and suspected acute or known chronic dissection of the aorta were examined with PET/CT 3 - 5 days after the onset of the pain. Nine patients had an acute, symptomatic type B dissection or an acute intramural haematoma, two had a secondary progressing, symptomatic dissection and seven patients had a stable dissection of the aorta not progressing compared to previous examinations. A Siemens Biograph 64 dedicated PET/CT machine was used. Image analysis was performed using TrueD Software (Siemens, Erlangen, Germany).

Results Patients with an acute dissection or with an acute intramural haematoma showed intensively elevated glucose metabolism at the dissection membrane and the adjacent vessel wall. Patients with secondary progressing dissections also exhibited increased FDG-uptake. In contrast, patients with chronic, non progressing dissection showed normal FDG-uptake. Quantitative analysis revealed that the ratio between SUVmax in the vessel wall and SUVmean of the blood pool is helpful to discriminate between acute and stable AD. A ratio of 1.5 : 1 was found as cut-off value by ROC analysis. This cut off value had a sensitivity of 100% and a specificity of 85.17% in discrimination of acute and stable aortic dissection.

Conclusions FDG-uptake at the dissection membrane occurs in acute but not in stable dissections of the aorta. Therefore PET/CT is potentially a useful biomarker to discriminate between these groups of patients