Study: FDG-PET + MR fusion helps evaluate breast cancer

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Fusion of prone 18F-FDG PET and MR breast scans increases the positive predictive value and specificity for patients in whom the MR outcome alone would be nonspecific, according to research published April 23 in the Breast Journal.

Fabio Ponzo MD, from the department of radiology at the New York University School of Medicine in New York City, and colleagues studied 36 women with 90 lesions detected on MR who consented to undergo a FDG-PET scan.

Two blinded readers evaluated the MR and the CT attenuation-corrected prone FDG-PET scans side-by-side, then after the volumes were superimposed or fused, wrote Ponzo and colleagues.

The median lesion size measured from the MR was 2.5 cm and histologically, 56 lesions were malignant, and 15 were benign, according to Ponzo and colleagues. Nineteen lesions were found to be benign after 20-47 months of clinical and radiologic surveillance.

The researchers calculated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for MR alone, FDG-PET alone, and fused MR and FDG-PET.

The sensitivity of MR alone was 95 percent, FDG-PET alone was 57 percent, and fusion was 83 percent. The increase in PPV from 77 percent in MR alone to 98 percent when fused and the increase in specificity from 53 percent to 97 percent were statistically significant, wrote Ponzo and colleagues.

The false-negative rate on FDG-PET alone was 26.7 percent, and after fusion this number was reduced to 9 percent. FDG-PET and MR fusions were helpful in selecting which lesion to biopsy, especially in women with multiple suspicious MR breast lesions, concluded Ponzo and colleagues.