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

Objectives 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 [18F]-FDG PET for investigation of heart transplanted patients suffering from suspicious symptoms, with previously ambiguous diagnosis.

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

Results PET revealed the cause of non-specific symptoms in nine of 17 patients; there were five cases of lymphoproliferative diseases (PTLD), two carcinomas, and two cases of infection. Four patients were rated false positive, one patient false negative, and three patients were correctly rated as negative. Sensitivity, specificity, 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 We find that [18F]-FDG PET is useful for detection of malignancies and infections causing non-specific symptoms in immunosuppressed heart transplant patients for whom conventional diagnostic evaluation had been inconclusive