CHEST Guidelines-Dual-Time-Point-Whole-Body-sup-18--sup-F-Fluorodeo

Dual-Time-Point-Whole-Body-sup-18--sup-F-Fluorodeo

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This study investigates the effectiveness of dual-time point 18 F-fluorodeoxyglucose (FDG) PET/CT imaging for differentiating between sarcoidosis and tuberculosis (TB) in patients with undiagnosed mediastinal lymphadenopathy. Sarcoidosis and TB are prevalent benign causes of this condition and are challenging to differentiate, especially in countries heavily burdened by TB. The study involved 117 patients, with subsequent follow-up to confirm diagnoses of sarcoidosis (88 patients) or TB (29 patients).<br /><br />The primary findings indicated that both diseases exhibited similar patterns of FDG uptake in lymph node groups, pulmonary parenchyma, and extrapulmonary organs. The FDG uptake was most common in the lower paratracheal and subcarinal lymph nodes. Notably, FDG uptake in paraaortic and interlobar lymph nodes was more frequent in sarcoidosis. The median maximum standardized uptake values (SUVmax) were compared at early and delayed times in both groups, with sarcoidosis showing slightly higher values.<br /><br />The research proposed an SUVmax (early) cutoff of 15.0 to potentially identify sarcoidosis, demonstrating good specificity (86.2%) and positive predictive value (88.6%) but poor sensitivity (35.6%) and negative predictive value (30.9%). Furthermore, many patients exhibited SUVmax (early) values exceeding 2.5 and 6.2, challenging previous beliefs about these cutoffs being able to differentiate benign and malignant lesions.<br /><br />The study concludes that dual-time point FDG PET/CT imaging is not effective in distinguishing between sarcoidosis and TB. The findings highlight the limited utility of FDG-PET scans for this purpose, underscoring the need for further research into distinguishing these conditions through other diagnostic methods or complementary imaging techniques. The research was conducted by a team at the Postgraduate Institute of Medical Education and Research, Chandigarh, India.

Keywords

dual-time point FDG PET/CT

sarcoidosis

tuberculosis

mediastinal lymphadenopathy

SUVmax

diagnostic imaging

specificity

sensitivity

Postgraduate Institute of Medical Education and Research

Chandigarh