Diagnosis of Lung Cancer Using Two-Phase Tl-201 SPECT and Modified Retention Image to View Tumor in the Collapsed Lung: Comparison with Bolus CT

In this report the usefulness of TI-201 SPECT and modified retention images in the differentiation of lung cancer and postobstructive collapse was studied. Two-phase TI-201 SPECT was performed in 20 lung cancer lesions in which postobstructive collapse was suspected on CT. Retention imaging was done afterward. Three types of TI-201 images were compared with the bolus CT images. Bolus CT differentiated lung cancer from postobstructive collapse in 7 of the 20 lesions (35%). TI-201 SPECT differentiated the two conditions in 9 of 20 lesions (45%) on early TI-201 SPECT and in 13 of 20 lesions (65%) on delayed imaging. With modified retention images, differentiation was possible in 13 of 20 lesions (65%). By combining delayed TI-201 SPECT and modified retention images, lung cancer alone could be demonstrated in 18 of 20 lesions (90%). Combined delayed TI-201 SPECT and modified retention images were more effective than bolus CT in delineating the extent of lung cancer in the presence of postobstructive collapse.