MR images invasive lobular cancer better than mammography

Compared with conventional imaging, contrast-enhanced MR provides a more accurate assessment of the extent of invasive lobular carcinoma in the breast, according to researchers in Canada.

"Invasive lobular carcinoma grows in a single-file fashion," said Dr. Supriya Kulkarni, an assistant professor of medical imaging at the University of Toronto.

Keeping this pathology in mind, Kulkarni and colleagues sought to examine how MR would compare with conventional imaging methods in determining the extent of disease. They prospectively studied 24 women over 16 months. The women all had biopsy-proven invasive lobular cancer, and the researchers used contrast-enhanced MR to preoperatively stage the cancer. They compared results from the CE MR with conventional imaging and lumpectomy or mastectomy.

Thirteen of the women had invasive lobular cancer, while 11 exhibited invasive lobular cancer with ductal features. Conventional imaging captured multicentric disease in 54% of the patients, compared with 83% using CE MR. The researchers found multifocal disease in 17% of the population using conventional imaging and in 29% using CE MR.

"MR revealed additional findings in 61% of the patients compared with conventional imaging," Kulkarni said.

In the 13 women who exhibited multicentric cancer on conventional imaging, CE MR showed:
· larger size of primary focus in 10 patients
· additional tumor foci in nine patients
· multifocal cancer in one patient
· confirmed multifocal disease in two patients

In the seven women with unifocal invasive lobular cancer as characterized by conventional imaging, CE MR showed:
· multicentric disease in two patients
· larger tumor size in five patients
· multifocal disease in two patients

Excisional pathology found both larger tumor size and multifocal cancer in the three women classified as having unifocal disease by both conventional imaging and MR. In all of the study participants, pathology revealed larger tumor sizes in 50% of the women and additional tumor foci in 46% of the women. Results of the study were presented at the RSNA conference.

Even though MR is better at depicting the extent of invasive lobular cancer than conventional imaging, more extensive disease should be anticipated, said Kulkarni.

For more information from the Diagnostic Imaging online archives:

Concerns remain for breast MR even as popularity grows

MRI, ultrasound find larger role in staging breast cancer

MRI changes clinical management in early breast cancer

MR enhances breast staging, diagnosis