Black women stand to gain most from breast MRI

Breast MRI can have a positive impact on clinical decision making for African American women with newly diagnosed breast cancer, leading to wider excisions and mastectomies, according to a new study carried out in Ohio. Age is also a factor.

"Younger women are significantly more likely to change their therapeutic management on the basis of MRI findings than their older counterparts," said Dr. Laura B. Shepardson, a radiologist at The Cleveland Clinic, in a scientific poster at RSNA 2008. "Of interest, pathologic diagnosis and stage of disease are not significant predictors of MRI's impact on clinical decision making."

Breast MRI is highly sensitive for detecting invasive carcinoma because of its superior imaging of soft tissues and its multiplanar capacity, which allows for 3D localization of disease, including documentation of multicentricity and/or multifocality. But few studies have addressed if and how breast MRI affects how black women make clinical decisions, she said.

A total of 306 African American patients had a breast MR exam at The Cleveland Clinic between 2003 and 2007. Of these, 111 (36%) were included in Shepardson's study because they had newly diagnosed ductal carcinoma in situ, invasive ductal carcinoma, or invasive lobular carcinoma. The women in the study had no prior history of radiotherapy or chemotherapy.

These patients all had stage 0, I, II, or III disease and underwent an MR exam within 30 days of diagnosis. They had a breast MR exam prior to initiating treatment and received their surgical treatment at The Cleveland Clinic.

The mean age of the sample was 57.9 years, and 61% (68) of patients were postmenopausal. Half of the women (55) had an asymptomatic presentation.

Contrast-enhanced MR exams were performed on a 1T Harmony system from Siemens, using 20 mL of gadopentetate dimeglumine (Magnevist) administered via a power injector, followed by a 5 mL saline flush. Imaging, clinical, operative, and pathology reports were seen by two independent reviewers, including a breast radiologist and a breast surgeon.

The treatment was breast conservation in 58% of cases (64 women) and mastectomy in 42% (47). Radiotherapy was performed in 64% of cases (71 women), chemotherapy in 48% (53), and endocrine therapy in 43% (48). In 13% of cases (14 women), the MR exam prompted a negative second look ultrasound and/or negative biopsy. These false-positive findings may partly reflect a learning curve for the interpreting radiologists.

In 51 cases, the radiologist thought MRI had a favorable impact on clinical management, while the comparable figure for the surgeon was 45 cases. This finding suggests there was no significant difference in the perceived benefit of MRI between radiologists and surgeons.

Shepardson admitted that this study had limitations. The sample included only African American women, limiting the ability to generalize about the results. Also, the current American College of Radiology guidelines recommend using a 1.5T system.

"This study was performed at a dedicated breast center from a single academic institution. If and how breast MRI impacts clinical decision making may differ in the community setting," she said.