Breast imaging with both FDG PET and MR provides additional information

Pretreatment PET with F-18 FDG as well as MR imaging provides useful diagnostic data, with PET showing a particular edge for prognosis, according to a study published online March 24 in the Journal of Nuclear Medicine.

Shingo Baba, MD, PhD, from the department of clinical radiology at the Graduate School of Medical Sciences, Kyushu University in Fukuoka, Japan, and colleagues assessed how standardized uptake value (SUV) of FDG PET imaging and the apparent diffusion coefficient (ADC) of diffusion-weighted MR imaging (DWI) correlate when evaluating patients with breast cancer to get a better picture of their respective diagnostic and prognostic value.

Results of the study showed that both techniques were effective for differentiating benign and malignant breast tumors. In fact, SUV and ADC together showed an inverse relationship. Higher SUV was positively correlated with higher nuclear grade and bigger breast tumors, as well as a triple-negative hormone receptor profile. ADC on the other hand correlated with positive human epidermal growth factor receptor 2 and negative progesterone receptor profiles.

“Both SUV and ADC are helpful parameters in differentiating benign from malignant breast tumors,” wrote Baba et al. “The use of SUV and ADC in combination may help in the diagnosis because of their inverse relationship."

For this study, a total of 79 patients aged 19-69 years, average of 49, were imaged with both FDG PET and DWI within a two-week period. Diagnoses uncovered 70 malignant tumors, including 65 cases of invasive ductal carcinoma, two micropapillary carcinoma, one squamous cell carcinoma, one mucinous carcinoma and one medullary carcinoma. There were 13 benign tumors found, including four cases of mastopathy, four of fibroadenoma, three of adenosis with atypia and two benign phyllodes tumor. The inverse relationship between ADC and SUV was insignificant for malignant tumors, but again useful when differentiating between malignant and benign growths.

Additionally, High SUV from PET imaging was linked to poor prognosis. However no such association was revealed with MRI and ADC.

“High preoperative SUV was associated with poor prognosis, but the contribution of ADC to prognosis prediction was small,” the researchers wrote.

This was the first prospective study of its kind proving prognostic value of FDG PET for breast cancer over and above MR imaging.