Evaluation of the components of mediastinal cystic lesions using imaging techniques

To identify and differentiate patients with mediastinal cysts from those with cystic tumors requiring surgery.

A total of 36 patients with mediastinal cystic lesions were enrolled. The patients were separated into two groups based on pathological findings : those with mediastinal cysts (n=23) and those with mediastinal tumors (n=13). The cystic components were measured using imaging parameters including mean computed tomography (CT) value, apparent diffusion coefficient (ADC), T1 signal intensity ratio (T1SIratio), and T2 signal intensity ratio (T2SI-ratio), acquired from magnetic resonance imaging (MRI) ; and standardized maximum uptake value (SUVmax) from¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT). Both groups were statistically compared.

Comparative parameters between the cysts and tumors revealed the following ratios : CT value, 40.9?21.2 versus (vs) 24.8?12.9 (p = 0.019) ;SUVmax, 1.18?0.50 vs 4.32?3.52 (p = 0.003) ; ADC, 3.46?0.96 vs 2.68?0.74 (p = 0.022) ; T1SI-ratio, 1.06?0.60 vs 1.35? 0.92 (p = 0.648) ; T2SI-ratio, 5.40?1.80 vs 4.33?1.58 (p = 0.194). However, there was no correlation between FDG uptake and ADC value.

SUVmax from¹⁸F-FDG PET/CT and ADC derived from MRI were effective in facilitating preoperative diagnosis to differentiate mediastinal cysts from tumors. However, these examinations may be complementary to one another, not dominant. J. Med. Invest. 66 : 106-111, February, 2019.