Contribution of F-18 FDG PET-CT in evaluation of cardiovascular surgery complications

Objectives Infectious complications following cardiovascular surgery(CVS) may be life-threatening, frequently presenting as fever of unknown origin (FUO).The role of PET-CT in this situation is undetermined. We present our recent experience using FDG PET-CT scans in detecting infectious complications post CVS.

Methods We studied retrospectively,14 pts (12 M ; 4 F- age range:31- 83 yrs) who underwent 3w-9m previously, varying CVS procedures including:Heart transplantation, cardiac valve replacement, aortic and iliac aneurysmal, and femoral artery-repairs;and coronary bypasses. 11/14 pts had whole-body PET-CT (WBPC) scans due to FUO; and 3/14- were referred for oncologic evaluation with known recent CVS. Final diagnoses were confirmed by:Re-operations, laboratory tests, clinical and imaging follow- up- to 12 m post CVS. All PET-CT scans were acquired using Philips GXL machine with qualitative FDG uptake analyses, using physiological large vessels and mediastinal uptake as normal references in defining uptake abnormalities. Mild/ diffuse incisional uptake was regarded secondary to recent CVS changes.

Results Of the 14 pts, who underwent WBPC- 10/11 pts with FUO- had markedly increased focal or elongated heterogenous FDG uptake with corresponding CT findings consistant with: In 3 pts- infections in sternal incisions; in 4- mycotic aneurysms,some with fistulisations; in 3- soft tissue abscesses. In 1of the 11pts with FUO scanned while on massive antibiotic treatment; and in 3/14 oncologic-non FUO pts - mildly increased uptake was seen in sternotomy incisions and repaired vessel walls, regarded as recent CVS changes. These results indicate a high yield of PET- FDG in detecting occult infection in post CVS, without F(+) result in our series, and 1F(-) in the single heavily treated patient.

Conclusions FDG PET-CT combined imaging results proved in our study highly valuable in assessing occult CVS complications, prompting interventions in life threatening infections, while effectively obviating unnecessary explorations when negative