Inconclusive triple diagnosis in breast cancer imaging: is there a place for scintimammography?

Scintimammography (SM) can be used as a complementary test to mammography in patients with suspected breast cancers. This study was undertaken to evaluate the impact of SM on the management of patients with a doubtful or discordant triple diagnosis-that is, mammography, ultrasound, and fine-needle aspiration cytology. The clinical question was variable: initial diagnosis of cancer, suspicion of recurrence, doubtful tumor extension, or search for a primary tumor.

We performed a retrospective study of 118 procedures in 104 patients with a suggestion of breast cancer, either at initial presentation or after treatment (relapse), with an inconclusive triple diagnosis. Planar and tomographic imaging was performed after injection of (99m)Tc-labeled methoxyisobutylisonitrile ((99m)Tc-MIBI). Results were compared with histopathologic analysis (surgery or core biopsy) in 82 cases and with clinical and imaging follow-up in 36 cases.

Breast cancer was proven in 69 cases. SM-SPECT had a sensitivity of 88.4% and a specificity of 67%. Eleven cancers were detected by SPECT, although planar images were negative. SM-SPECT was more sensitive in patients scanned at initial presentation (95%) than in those with suspected recurrence (81%). SM-SPECT correctly evaluated multicentricity or bilaterality in 8 of 11 patients and resulted in an increased tumor size in 8 patients. Overall, SM-SPECT modified the patient management in 58 of 118 cases (49%): SM made the diagnosis of cancer in 30 cases with doubtful or discordant triple diagnosis and ruled out malignancy in 28 cases.

SM-SPECT is a useful complementary tool for the diagnosis and evaluation of disease extent in patients with an inconclusive triple diagnosis including fine-needle aspiration. The procedure altered the patient management in 49% of the population. These results must be confirmed in a prospective trial.