Combined imaging techniques using multiparametric 18fluorodeoxyglucose PET-MRI allow differentiation between benign and malignant breast tumors with a diagnostic accuracy of 96%, according to a report published online June 24 in Clinical Cancer Research.
This in turn permits a "remarkable" reduction in breast biopsies, said Dr. Katja Pinker and her associates at the Medical University of Vienna.
Dr. Katja Pinker
In a single-center feasibility study, the investigators compared the prognostic accuracy of several different combinations of breast imaging in 76 consecutive women aged 25-86 years (mean age, 55.7 years) who were seen during a 3-year period and had suspicious findings on mammography or breast ultrasonography. The lesions ranged in size from 5 mm to 77 mm (median, 29.2 mm); 53 proved to be malignant and 23 were benign.
Only one combination of imaging techniques – multiparametric 18fluorodeoxyglucose (FDG) PET-MRI – achieved an overall diagnostic accuracy of 96%, with a sensitivity of 100% and a specificity of 87% in distinguishing cancers from benign tumors.
Multiparametric FDG PET-MRI includes:
• Dynamic contrast-enhanced MRI, which provides high-resolution anatomic information and depicts increased microvascular density and capillary leaks, which are markers of angiogenesis in malignant tumors.
• Diffusion-weighted imaging that shows cellular diffusivity on a molecular level, which typically is restricted in malignant tissue.
• Three-dimensional proton spectroscopic imaging, which detects elevated levels of the metabolite choline, a marker of increased cell-membrane turnover.
• FDG PET that allows assessment of glucose consumption, which typically is increased in neoplastic processes.
Thus, this combination of imaging techniques simultaneously assesses several processes involved in cancer development: angiogenesis, molecular capabilities, glucose consumption, and metabolite concentration, the investigators said (Clin. Cancer Res. 2014 June 24 [doi: 10.1158/1055-9965.EPI-13-1284]).
Fluorodeoxyglucose, "currently the ‘workhorse’ in clinical PET imaging, has a good sensitivity but limited specificity, as several types of benign breast tumors and conditions can be 18FDG-avid and mimic malignancy," Dr. Pinker and her associates wrote. "However, a multitude of new, targeted radiotracers for visualization of processes involved in cancer evolution are being developed and investigated." These tracers should increase the specificity of this combination of imaging techniques, which will soon make multiparametric PET-MRI an important tool in detecting breast cancer, staging the disease, and monitoring treatment response, they said.
This study was funded by the Austrian Society of Senology, the Austrian National Bank "Jubiläumsfond," and the Medical Scientific Fund of the Mayor of Vienna. Dr. Pinker and her associates reported no financial conflicts of interest.