Abstract: Objective To explore the value of 18F-FDG PET/CT in the diagnosis of extrapulmonary tuberculosis (ET). Methods
The imaging data from 88 cases of ET undergoing 18F-FDG PET/CT examinations between August, 2005 and May, 2011 were
analyzed retrospectively. Results All the 88 cases showed high 18F-FDG uptake on PET imaging with a SUVmax ranging from
1.3 to 23.2. In 19 of the 88 cases, the extrapulmonary lesions were misdiagnosed as malignant neoplasms. Twenty-two patients
were found to have phthisis. According to locations, the lesions were classified into 4 basic types, namely membranous
tuberculosis (36 cases) with soft tissue thickening as the main manifestation (only 6 cases did not present with obvious
thickening), lymphatic tuberculosis (44 cases) with lymph node enlargement (ill-defined edge in 22 cases, central necrosis in 3
cases, and ring-like enhancement in enhanced CT scan in 6 cases), osteoarticular tuberculosis ( 28 cases) with the main findings
of osteolytic destruction with or without osteosclerosis (tuberculosis of the spine was characterized by disc damage and
paravertebral cold abscess; only one case showed high FDG uptake without bone destruction), and organ tuberculosis (25
cases) involving the liver, spleen, pancreas, kidney and brain, where lesions of low density were detected in CT scan (3 cases
showed ring-like enhancement). In cases of organ tuberculosis, nasopharyngeal and laryngeal tuberculosis showed soft tissue
thickening, and intestinal tuberculosis presented with slight intestinal wall thickening (involving multiple segments in 2 cases).
Of the 88 cases, 30 had two or more than two lesion types. Conclusion PET/CT can accurately demonstrate the morphology,
extent of involvement and uptake activity of the ET lesions to assist the early diagnosis and treatment of ET. Enhanced CT scan
also helps in the differential diagnosis of the lesions.