Comparative evaluation of 99mTc-depreotide and 201Tl chloride single photon emission tomography in the characterization of pulmonary lesions.
OBJECTIVE
To compare (99m)Tc-depreotide and (201)Tl chloride SPET in the characterization of pulmonary lesions.


METHODS
Fifty-seven pulmonary lesions from 33 patients suspected of malignancy in computed tomography, were assessed by (99m)Tc-depreotide and (201)Tl early and delayed SPET imaging. Images were visually assessed and the tumour-to-normal (T/N) lung activity ratio for early (ER) and delayed (DR) scans and the retention index (RI), were calculated in every lesion. A final diagnosis was reached for all lesions, based either on histology or prolonged clinical and radiological follow-up.


RESULTS
Twenty-three lesions were characterized as malignant and 34 benign. In visual analysis, all malignant lesions accumulated both tracers resulting in sensitivity and negative predictive values of 100%. However, false positive interpretations resulted in a specificity of 64.7% and 67.6% for (99m)Tc-depreotide and (201)Tl, respectively. ER and DR of both agents and the RI of (99m)Tc-depreotide were significantly higher in malignant, compared to benign lesions. In defining thresholds of abnormality from ROC analysis, a significant increase in specificity was observed for both tracers in both scan phases (91.2% for all), as compared to visual analysis (P<0.01). There was no significant difference in the diagnostic performance between (99m)Tc-depreotide DR and (201)Tl DR, although the former provided the highest T/N ratio.


CONCLUSIONS
This study demonstrates that (99m)Tc-depreotide and (201)Tl SPET are equally effective and may be useful in the non-invasive determination of lung malignancy. The specificity of both techniques is significantly improved by quantifying radiopharmaceutical accumulation in pulmonary lesions.
Boundas
Dimitrios
D
Department of Nuclear Medicine, Aristotle University Medical School, Hippokration Hospital, 3 Chimonidou Street, 55133 Thessaloniki, Greece. dibu@in.gr
Karatzas
Nikolaos
N
Moralidis
Efstratios
E
Arsos
Georgios
G
Drevelengas
Antonios
A
Pistevou-Gompaki
Kiriaki
K
Karakatsanis
Constantinos
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D013004:Somatostatin / Q000031:analogs & derivatives*; D013793:Thallium; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C027549:thallium chloride; D013004:Somatostatin; C444119:technetium Tc 99m depreotide; D013793:Thallium