The diagnostic role of (201)T1 SPET imaging in patients with lung tumours: Comparison with computed tomography

The aim of the study was to evaluate the use of Tl-201 single photon emission tomography (SPET) in differentiating histological types and lymph node sizes of lung tumours based on the early uptake ratio (EUR), delayed uptake ratio (DUR) and retention index (RI). We also wished to compare the effectiveness of Tl-201 SPET and computed tomography (CT) in detecting lymphadenopathy. We examined 41 subjects using both Tl-201 SPET and CT. Fifty-seven lymph nodes were detected and were grouped according to size. The EUR, DUR and RI were determined and analysed using Student's t-test and a P-value < 0.05 was considered significant. Lymphadenopathy detected by both Tl-201 SPET and CT correlated with the operative findings. There were no statistically significant differences in the EUR, DUR and RI between the various histological types. Statistically significant differences in EUR were noted between lymph nodes > 5 cn in size and those 3-5 cm in size, as well as between those < 3 cm and > 5 cm in size. A significant difference in DUR was seen between lymph nodes < 3 cm and > 5 cm in size. No significant differences were seen for the RI. The specificity, sensitivity and accuracy of Tl-201 SPET were 81.3, 90.2 and 87.7% respectively, whereas for CT they were 81.3, 100 and 94.74% respectively. In conclusion, quantitative analysis with Tl-201 SPET was unable to differentiate with accuracy between histological types but it could differentiate between nodes of varying sizes. However, CT had a better specificity and accuracy.