Diagnostic role of whole-body [18F]-FDG positron emission tomography in patients with symptoms suspicious for malignancy after heart transplantation

Background: Increased rates of malignancies and infections occur in transplant patients under immunosuppression, but the resultant clinical symptoms, and results of physical examination, chest X-ray, abdominal ultrasonography and laboratory findings are frequently difficult to interpret or inconclusive. The aim of the present study was to investigate the usefulness of whole-body [(18)F]-FDG PET for investigation of heart transplant patients suffering from suspicious symptoms, with a previously ambiguous diagnosis.

Methods: Seventeen consecutive patients (8 women; 48 ± 22 years) with non-specific symptoms (lymphadenopathy, fever of unknown origin or recurrent febrile temperatures, weight loss, abdominal pain, night sweating, cough or generally reduced physical condition) were evaluated retrospectively. All patients underwent whole-body [(18)F]-FDG examinations by PET (7 patients) or PET/CT (10 patients) at 8 ± 6 (range 0.1 to 21) years after orthotopic heart transplantation (OHT). During a follow-up of 28 ± 25 months, results of bone marrow biopsies, and histologic and/or microbiologic findings were registered and retrospectively compared with the PET results.

Results: PET revealed the cause of non-specific symptoms in 9 of 17 patients; there were 5 cases of lymphoproliferative disease (PTLD), 2 carcinomas and 2 cases of infection. Four patients were rated false positive, 1 patient false negative and 3 patients were correctly rated as negative. Sensitivity, specificity and positive and negative predictive values were 0.90, 0.43, 0.69 and 0.75, respectively, giving an overall diagnostic accuracy of 0.71.

Conclusions: A non-invasive strategy of using whole-body [(18)F]-FDG PET or PET/CT in heart transplant recipients with non-specific unexplained symptoms may offer diagnostic stratification for malignancy and infections with a high sensitivity and modest diagnostic accuracy. These findings require prospective confirmation.