Intraindividual Comparison of F-18-Fluorodeoxyglucose and Tc-99m-Tetrofosmin in Planar Scintimammography and SPECT

Since the comparative value of several nuclear medicine investigations for breast cancer has not been established, the rationale of this study was to examine the diagnostic performances of F-18-fluorodeoxyglucose (FDG) and Tc-99m-tetrofosmin both in single photon emission computed tomography (SPECT) and planar technique in an intraindividual comparative study.

A total of 54 patients with suspected breast cancer (48 malignant and 9 benign lesions) was investigated by planar and SPECT imaging with both FDG and tetrofosmin within the last preoperative week. Pathohistological confirmation of the diagnosis was obtained in all patients.

Overall sensitivites/specificities of FDG planar imaging and SPECT and tetrofosmin planar imaging and SPECT were 56%/78%, 81%/89%, 59%/57%, and 63%/86%, respectively. For tumors ⩽2 cm the respective figures were 27%/83%, 68%/100%, 41%/80%, and 50% /80%, and for tumors >2 cm 81%/67%, 92%/67%, 75%/50%, and 75%/100%. Sensitivity was higher with FDG SPECT than with the other imaging modalities $\text{P = 0}$ and significantly lower for tumors ⩽2 cm with all the techniques investigated. In 20 out of 21 patients with diverging scintigraphic findings, FDG SPECT was either true positive or true negative. In 15 patients with axillary lymph node metastases, sensitivities were 33%, 73%, 36%, and 50%, respectively.

In conclusion, sensitivity of FDG SPECT for breast cancer and axillary lymph node metastases is superior to FDG planar imaging and to tetrofosmin planar imaging and SPECT. For tumors ⩽2 cm and axillary lymph node metastases, none of the imaging modalities yielded acceptable results. FDG SPECT seems a suitable imaging procedure for breast tumors >2 cm, if dedicated PET is not available.