Tuberculous lymphadenitis: FDG PET and CT findings in responsive and nonresponsive disease.

PURPOSE: No data is available on the different FDG PET and CT findings in the lymph nodes (LN) of patients with HIV and tuberculosis (TB) who respond compared with those who do not respond to anti-TB treatment by 4 months after initiation of TB treatment. These findings were the focus of our study. METHODS: PET/CT scans performed at 4 months after initiation of TB treatment in 20 consecutive HIV patients were analysed. SUVmax values were obtained for all regions of LN involvement. The diameter of the LNs was measured and the CT enhancement (LNs showing peripheral rim enhancement with central low attenuation, PRECLO, in comparison with homogeneously involved LNs) and the calcification patterns of involved LNs assessed. The relationship between the PET and CT findings and the clinical outcome, response or nonresponse, was evaluated. RESULTS: FDG PET identified 91 sites of LN involvement, 20 of which were not identified by CT. SUVmax values were significantly higher in nonresponders (8 patients, SUVmax 11.2 ± 4.0, mean ± SD) when compared to responders (12 patients, SUVmax 2.6 ± 2.3; p = 0.0001). In ROC analysis (AUC 0.952) a cut-off value of 4.5 for SUVmax yielded a sensitivity and specificity of 95% and 85% for discriminating nonresponding from responding LNs. LNs were significantly larger in nonresponders (1.9 ± 0.4 cm) than in responders (1.4 ± 0.4 cm; p = 0.0001); the AUC in the ROC analysis was 0.76. PRECLO LNs were significantly larger (2.2 ± 0.3 cm) than homogeneous involved LN basins (1.5 ± 0.4 cm) and LN basins with calcification (1.4 ± 0.5 cm; p = 0.001). Using the presence of at least one LN basin with PRECLO as a criterion for nonresponse, responders could be separated from nonresponders with a sensitivity of 88% and a specificity of 66%. CONCLUSION: LNs responding to TB treatment could be differentiated from nonresponding LNs with a sensitivity and specificity of 95% and 85% using a SUVmax cut-off value of 4.5 and a sensitivity and specificity of 88% and 66% using the presence of at least one LN basin with PRECLO.

Positron emission tomography in the prediction of inflammation in children with human immunodeficiency virus related bronchiectasis.

There is a lack of objective tools to reliably diagnose exacerbations in bronchiectasis. The primary aim of this study was to assess the ability of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹8F-FDG PET/CT) to detect sites of active inflammation in children with human immunodeficiency virus (HIV)-related bronchiectasis with or without exacerbations. The secondary aim was to assess whether ¹8F-FDG-PET/CT results are in agreement with local and systemic inflammatory markers and markers of HIV disease activity. Forty-one children with HIV-related bronchiectasis underwent ¹8F-FDG PET/CT. Data on the presence of a clinical exacerbation were recorded. Serum was collected for CD4 count, HIV viral load, C-reactive protein (CRP) and cytokines IL-8, INF-γ and TNF-α. Induced sputum samples were processed for microbiological culture and for IL-8, INF-γ and TNF-α.Mean age of all children was 8.2 ± 2.2 years. Twelve subjects showed F-FDG lung uptake while six of them had an exacerbation. There was no difference in the ¹8F-FDG uptake in participants with or without an exacerbation (P=0.613). Fluorine- 18-FDG-PET had a good correlation with the presence of consolidation (P=0.01, OR=6.67). The mean CRP was higher in the subjects with (18)F-FDG uptake when compared to those without uptake (51.96 ± 95.12 vs. 13.26 ± 19.87), although this difference was not significant (P=0.09). In conclusion, the ¹8F-FDG-PET lung uptake technique could not reliably predict the presence of an exacerbation in children with HIV and bronchiectasis, and its diagnostic value was limited to identifying disease activity on the scan in acute pneumonia cases. Fluorine-18-FDG-PET had no significant correlation with CRP or with other inflammatory biomarkers and markers of HIV disease activity.