Detection of myocardial inflammation by 18F-FDG-PET/CT in patients with systemic sclerosis without cardiac symptoms: a pilot study.

Objective. Primary cardiac manifestation is a common complication of systemic sclerosis (SSc) with poor prognosis. The aim of the current study was to detect potential myocardial inflammation present in asymptomatic SSc patients by 18F-FDG-PET/CT and to investigate its relationship with early signs of myocardial dysfunction as detected by 2D speckle tracking echocardiography (2DSTE). Methods. Sixteen consecutive patients with SSc and 9 control patients without clinical evidence of cardiac involvement were enrolled in the study. On 18F-FDG-PET acquired images blood-pool normalised SUV ratio and heterogenity index (HI: standard deviation of SUV divided with mean SUV) were calculated. Within 24 hours all SSc patients underwent 2DSTE strain analysis. Results. Eight of 16 SSc patients were found to be visually PET-positive and showed significantly higher myocardial 18F-FDG SUV ratio (1.78 +/- 0.74 vs. 0.98 +/- 0.03; p<0.05) and heterogenity index (0.13 +/- 0.02 vs. 0.05 +/- 0.02; p<0.001) as compared to the control group. FDG-PET/CT derived values did not differ significantly between visually PET-negative (8/16) and control patients (SUV ratio: 0.98 +/- 0.05 vs. 0.98 +/- 0.03; HI: 0.05 +/- 0.01 vs. 0.05 +/- 0.02). Global left ventricular longitudinal strain values did not differ significantly between PET-positive and negative patients (17.18 +/- 3.49% vs. 17.59 +/- 3.65%). Conclusion. Myocardial inflammation, as a potential sign of early cardiac involvement can be detected by 18-FDG-PET/CT in a considerable percentage of systemic sclerosis patients presenting without cardiac symptoms.