Efficiency of 18F-FDG and 99mTc-depreotide SPECT in the diagnosis of malignancy of solitary pulmonary nodules.
OBJECTIVE
The purpose of the study was to compare ( 18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and ( 99m)Tc-depreotide single-photon emission computed tomography (SPECT) in the diagnosis of malignancy of solitary pulmonary nodules (SPNs).


METHODS
Twenty-eight patients without any history of cancer and presenting an SPN (0.8-3 cm in size) underwent FDG PET and depreotide SPECT. Depreotide SPECT and FDG PET were performed on a double-head gamma camera and a dedicated PET scanner respectively. Twenty-five out of 28 lesions were removed by thoracotomy or assessed by biopsy (n=1) and histologically examined. A strategy of serial CT scanning was adopted in the three remaining patients.


RESULTS
Histological findings revealed 18 malignant nodules and seven benign lesions. Stability over a 2-year period indicated a benign process in the remaining three cases. Both techniques yielded true positive results in 15 of the 18 cancers. FDG PET identified two additional adenocarcinomas not detected by depreotide SPECT. A carcinoid tumour not visualised on FDG PET was identified by depreotide SPECT. Seven of the ten benign lesions did not reveal tracer uptake on either depreotide SPECT or FDG PET. Both techniques showed false positive results for the same two lesions. One more false positive was seen on FDG PET. FDG PET and depreotide SPECT had a sensitivity of 94.4% and 88.9% respectively; this difference was not significant. In our experience, depreotide SPECT and FDG PET are equally sensitive (92.3%) for large (>1.5 cm) and equally specific (85.7%) for small (up to 1.5 cm) SPNs suspicious for malignancy.


CONCLUSIONS
This study showed( 18)F-FDG PET to be more sensitive than ( 99m)Tc-depreotide SPECT in the diagnosis of malignancy of SPNs. However, the combination of both techniques may provide additional accuracy.
Halley
Arnaud
A
Department of Nuclear Medicine, University Hospital, Avenue de la cote de Nacre, 14033 Caen, France. halley-a@chu-caen.fr
Hugentobler
Alexis
A
Icard
Philippe
P
Porret
Emilie
E
Sobrio
Franck
F
Lerochais
Jean-Philippe
JP
Bouvard
Gerard
G
Zalcman
Gerard
G
Agostini
Denis
D
D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D005602:France; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D010865:Pilot Projects; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D013004:Somatostatin / Q000031:analogs & derivatives*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013004:Somatostatin; C444119:technetium Tc 99m depreotide