Limited value of ⁹⁹mTc depreotide single photon emission CT compared with CT for the evaluation of pulmonary lesions.

OBJECTIVES

A contrast-enhanced multidetector CT (MDCT) scan is the first choice examination when evaluating patients with suspected lung cancer. However, while the clinical focus is on CT, research focus is on molecular biological methods whereby radiolabelled pharmaceuticals are injected into participants and target malignant lung tumours. We examined whether a contrast-enhanced MDCT scan supplied with an additional non-contrast enhanced high-resolution CT scan, or a newer but more expensive (99m)Tc depreotide single photon emission CT (SPECT) scan, was the better first-choice examination for the work-up of pulmonary lesions. Furthermore, we examined whether a (99m)Tc depreotide SPECT scan was an appropriate second-choice examination for patients with indeterminate lesions.

METHODS

140 participants were included in the analysis. CT images were given a malignancy potential rating of 1, 2 or 3 with higher rating being indicative of disease. (99m)Tc depreotide SPECT images were graded either positive or negative. Histopathology and CT follow-up were used as reference standard. Sensitivity, specificity and diagnostic accuracy were calculated.

RESULTS

Overall sensitivity, specificity and diagnostic accuracy of CT were 97%, 30% and 84%, respectively. Overall sensitivity, specificity and diagnostic accuracy of (99m)Tc depreotide SPECT were 94%, 58% and 76%, respectively. For indeterminate lesions sensitivity, specificity and diagnostic accuracy of (99m)Tc depreotide SPECT were 71%, 68% and 69%, respectively.

CONCLUSION

Both CT and (99m)Tc depreotide SPECT made valuable contributions to the evaluation of pulmonary lesions. (99m)Tc depreotide SPECT results were not superior to CT results and did not contribute further to the diagnostic work-up. Regarding indeterminate lesions,( 99m)Tc depreotide SPECT sensitivity was too low.