18F-FDG PET/CT detects systemic involvement in sarcoidosis

Monitoring the Therapy of Extensive Osseous Sarcoidosis With FDG PET/CT

FDG PET/CT was performed in a 47-year-old man to evaluate possible malignancy of the spine revealed by MRI. The PET images revealed numerous focal FDG activity throughout the skeletal system. In addition, multiple foci of the increased activity in the mediastinal and hilar nodes were noted, suggestive of sarcoidosis, which was proven following biopsy. Therapy for sarcoidosis was initiated. In the subsequent 4 follow-up FDG PET/CT scans, the activity in both the bones and mediastinal/hilar regions fluctuated. However, anatomical abnormality in the bones on the CT images was never visualized during the entire clinical course.

Current clinical use of 18FDG-PET/CT in patients with thoracic and systemic sarcoidosis

PURPOSE

This study assessed the role of whole-body (18)fluorodeoxyglucose positron-emission tomography/computed tomography ((18)FDG PET/CT) in the restaging and follow-up of patients with sarcoidosis previously studied by multidetector computed tomography (MDCT).

MATERIALS AND METHODS

This retrospective study enrolled 21 patients to evaluate the sensitivity, specificity and accuracy of (18)FDG-PET/CT and MDCT. The results of the two techniques were compared with the Mc Nemar test. Cohen's K was used to compare concordance at the different lesion sites.

RESULTS

The sensitivity, specificity and accuracy of (18)FDG-PET/CT were 80, 66.67, and 76.19 %, respectively. The sensitivity, specificity and accuracy of MDCT were 93.33, 33.33, and 76.19 %, respectively. In 16 patients who underwent whole-body MDCT, the sensitivity, specificity and accuracy values were 91.67, 81.25, and 50 % (MDCT) and 100, 50, and 87.5 % ((18)FDG-PET/CT).

CONCLUSIONS

(18)FDG-PET/CT is useful in evaluating the extent of sarcoidosis and recognising lesions at different sites, including lymph nodes, lungs, liver, spleen and bone. It also improves the interpretation of the morphological lesions seen on MDCT and depicts a larger number of lesions. Therefore, (18)FDG-PET/CT could be used to complement other more traditional techniques for the restaging and follow-up in patients with sarcoidosis.

Unsuspected Active Sarcoidosis Diagnosed by 18F-FDG PET/CT During the Search for a Primary Tumour in a Patient with Bone Lesions

Sarcoidosis is a systemic chronic inflammatory disease of unknown aetiology, characterised by granulomatous lesions with heterogeneous clinical manifestations affecting multiple organs and tissues. Although the respiratory system is most commonly affected, the disease may also present with bone lesions. We report the case of a 31-year-old woman who presented with low back pain and no history of cancer and who was found to have suspicious lesions involving the entire spine on magnetic resonance imaging (MRI). The patient underwent 18F-fluorodeoxyglucose (FDG) PET/CT to search for a primary tumour and for staging purposes. 18F-FDG PET/CT revealed a pattern of hypermetabolic activity in widespread skeletal lesions and in a single left cervical lymph node. The primary tumour was not found, thus suggesting a haematologic disorder. Subsequent biopsies of a cervical lymph node and of bone tissue from L4 revealed active sarcoidosis with no evidence of cancer. This underlines the importance of considering all alternatives when hypermetabolic lesions are found on 18F-FDG PET/CT. Furthermore, 18F-FDG PET can be very useful to indicate accessible sites for guiding fine-needle aspiration cytology (FNAC).

18F-FDG PET/CT imaging of extensive systemic sarcoidosis with epididymal involvement

Sarcoidosis rarely involves the male reproductive tract. We present an unusual case of extensive systemic sarcoidosis with epididymal involvement. The ¹⁸F-FDG PET/CT demonstrated extensive foci of hypermetabolic activity involving multiple lymph nodes, liver, epididymides, muscles, and subcutaneous tissues. After immunosuppressive therapy, a follow-up PET scan showed almost complete disappearance of the FDG accumulation except for in the hilar lymph nodes.