We sought to determine whether PET/CT imaging with 68 Ga-citrate could be of value in distinguishing benign from malignant lung pathology in a setting with a high prevalence of granulomatous diseases. Methods Thirty-six consecutive patients with indeterminate lung lesions prospectively underwent dual time point (60 and 120 min) 68 Ga-citrate PET/CT study prior to lung biopsy. Qualitative and semi-quantitative measures of tracer uptake in the lung lesions (SUVmax) were compared to the histopathology in order to establish an imaging pattern to distinguish benign from malignant lesions.Results Fourteen patients (38.9 %) were diagnosed with a malignant lesion, 12 (33.3 %) with tuberculosis (TB), and 10 participants (27.8 %) with other benign lung lesions. At 60-min post-injection, patients who were diagnosed with a malignant lesion (n = 14) demonstrated a mean SUVmax of 3.36 ± 1.14, with a median value of 3.04 (min = 1.56, max = 4.65).Those with TB (n = 12) demonstrated a SUVmax of 3.99 ± 2.28, and a median value of 3.71 (pct 25 = 2.19, pct 75 = 4.95). In patients with other benign lesions (n = 10), the following values were observed: a SUVmax of 2.70 ± 1.31, a median value of 2.50 (pct 25 = 1.76, pct 75 = 3.59). The mean values of these three types of pathology were not statistically significant (p = 0.1919), and therefore the SUVmax could not be used to accurately distinguish between these lesions using both early and delayed imaging. Conclusion This study, as the first 68 Ga-citrate PET/CT in humans for the in vivo imaging of lung pathology, demonstrated its potential for the detection of both malignancy and TB. However, 68 Ga-citrate seemed incapable of providing a clear distinction between malignant and benign lung lesions in a setting with a high prevalence of granulomatous diseases such as TB.

Abstract:Introduction: A 37-year-old man was referred for PET/CT with the following diagnostic challenge: a longstanding smoking history, histologically confirmed TB and sarcoidosis with worsening chest-related symptoms and a non-responsive right upper lobe lung lesion (as detected on CT). Materials and Methods: PET/CT imaging was performed with18 F-FDG and followed by imaging with 18 F-fluoroethylcholine in an attempt to better characterize the lung lesion. This was followed by biopsies of the right upper lobe nodule, the pleura and a brain lesion.Results: Both tracers demonstrated increased uptake in the lung lesion and in multiple lymph node groups. Histology revealed the presence of a granulomatous disease in the lung lesion, the pleura and in the brain. Follow-up evaluation with 18 F-fluoroethyl-choline PET/CT demonstrated some improvement, which correlated with clinical improvement. Conclusion: Tuberculous lesions demonstrate increased accumulation of18 F-fluoroethyl-choline on PET/CT, which may be useful in the evaluation of treatment response. When used in combination with 18 F-FDG, it could be of value in distinguishing malignant lesions from tuberculosis.