Superior Detection of DCIS with Gamma Imaging
A team from George Washington University conducted a small, retrospective review to evaluate the ideal imaging modality to evaluate women for DCIS. The group compared findings from standard mammography, MRI and Breast-Specific Gamma Imaging (BSGI).
Twenty patients with 22 biopsy proven breast cancer lesions all underwent evaluation with BSGI and MRI, a GE 1.5T system with a dedicated breast coil. BSGI imaging was completed with a Dilon 6800, which is a gamma camera with small field of view and high-resolution.
All the patients were initially screened with mammography. Findings from mammography were suspicious for DCIS based on the presence of microcalcifications or risk factors.
The team compared the sensitivity of each modality in identifying DCIS, as well as sensitivity of BSGI compared to pathologic assessment of specimens. Findings were compared for statistical significance using a two tailed t-test and assessment of confidence intervals.
Mammography had the lowest rate of detection at 82 percent, followed by MRI with 88 percent detection. BSGI had the highest rate of detection at 91 percent. This difference between modalities was not statistically significant.
BSGI may be especially useful in detecting smaller malignant breast lesions. Small DCIS foci are difficult to capture with current MRI technology. Importantly, two cases of DCIS were only noted with BSGI, which demonstrated increased tracer uptake in the contra lateral breast. These findings had not been noted with mammography screening. Alternatively, BSGI was also implicated for two false negatives. BSGI was effective in capturing small lesions, less than 5mm, as well as residual disease following surgical excision.
Other challenges of MRI for DCIS include a higher rate of false-negatives, estimated to be upwards of 50 percent. The positive predictive value of this imaging modality has marked variability.
The team published their findings in the Academic Radiology journal August issue.
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