Combined MRI/FDG-PET proves useful in breast cancer

FDG-PET and MRI are comparable in imaging patients with suspected breast cancer or recurrent disease, according to researchers in Germany and Switzerland.

Although the two investigative teams differed as to what modality should be employed first, both agreed that combining results from MRI and PET helps in the detection and staging of primary tumors. Both also suggested the combined PET/MR imaging approach is useful to evaluate patients with suspected recurrence.

In one study, Swiss investigators assessed 32 patients with suspected locoregional and chest wall recurrence and suspected secondary tumor. They found that PET and MR had comparable accuracy for the detection of malignancies of the breast. They also found that the detection of distant metastases with whole-body PET could influence patient management.

Sensitivity was 79% and 100%, specificity was 94% and 72%, and accuracy was 88% and 84% for MRI and PET, respectively, for this trial.

In the other study, German researchers evaluated dynamic-enhanced MR mammography with FDG-PET to detect and characterize suspicious breast lesions. They included 40 patients assessed at clinical examination, mammography, or ultrasound. They found the combination of MR, mammography, and PET could help reduce the number of unwarranted biopsies.

Sensitivity and specificity were 89% and 63%, respectively, for MR, and74% and 91% for PET.

Both investigative teams published their results in the July issue of European Radiology.

In patients with known tumors and suspected distant disease, PET is the right thing to do, said coauthor Dr. Gustav von Schulthess, director of nuclear medicine at the University of Zurich Hospital. Physicians should also use MRI to assess suspicious focal breast lesions that are problematic.

There are always patients who would like to have more information before a biopsy is done, said principal investigator Dr. Gerhard W. Goerres, from the nuclear medicine division at the University of Zurich.

In some patients, the biopsy site is not easily defined using mammography or ultrasound. In these cases, the use of one method or the combination of both could provide additional useful information, especially when biopsy is difficult or not an option, Goerres said.

The researchers warned that combined PET/MR strategy should be reserved for selected cases. While the approach seems academically interesting, it would not be justified in a routine clinical setting due to its high cost.

For more information from the Diagnostic Imaging archives:

? Concern remains for breast MR even as popularity grows
http://www.dimag.com/db_area/archives/2003/0309.vision.di.shtml

? PET imaging of breast cancer guides treatment decisions
http://www.dimag.com/db_area/archives/2002/0206.cme.di.shtml