PORTAL EXCLUSIVES

Image reformation aids MR breast cancer screening


Advanced visualization technology aided diagnostic interpretation during the U.K. MRI in Breast Screening (MARIBS) trial, which recruited 732 women--who had at least a 50 percent risk of being a breast cancer susceptibility gene 1 (BRCA1), BRCA2 or TP53 gene mutation carrier--for an annual breast MRI and two-view mammogram over a nearly seven-year period (Aug. 1997- March, 2003).

“The multicenter MARIBS trial presented an opportunity to identify, on MR and mammographic images, any specific morphologic or enhancement features in cancers found in BRCA1 or BRCA2 mutation carriers or in women with a strong family history of breast cancer,” the authors wrote in a retrospective analysis published this month in Radiology.

Women in the clinical trial underwent screening for one to seven years and follow-up until January 2005. U.K. scientists reviewed the imaging features of screening-detected cancers to identify specific abnormalities to aid earlier detection or facilitate differentiation of cancers in this patient cohort.

Coronal T1-weighted MR image in 33-year-old BRCA1 carrier obtained after contrast agent injection show 2-cm invasive cancer of grade 3 with 1-cm DCIS lesion component, with irregular margins and rim enhancement diagnosed in year 2; no abnormality was seen in year 1. Red lines were used to locate tumor position in three dimensions at diagnostic and prior examinations. Image and caption courtesy of the Radiological Society of North America.
A total of 39 cancers were found during the MARIBS trial—29 in BRCA1 and BRCA2 carriers, two in TP53 carriers and eight in women in whom a gene had not been identified but who had a family history of breast cancer with or without ovarian cancer.

MR images were obtained from systems from four different manufacturers: GE Healthcare; Siemens Healthcare; Philips Healthcare and Picker (acquired by Philips in 2001).

“Images were read by using commercially available analytic tools, such as subtraction, multiplanar reconstruction, maximum intensity projection from subtracted images and dynamic analysis of the 3D dynamic series (FuncTool; GE),” the authors wrote.

The researchers noted that some of the earlier studies in the trial employed reformation technology, MRIB-view from the Institute of Cancer Research in Sutton, England, which offered similar functionality.

Images from prior screening MR exams were read after the images from the diagnostic exam had been reviewed to establish whether any abnormality could be identified retrospectively at the site of the tumor.

The clinicians found that on MR images, cancers at a prior examination were of smaller size, showed less enhancement, and were more likely to have a type 1 enhancement curve (associated more commonly with benign lesions) compared with those cancers on images at the subsequent diagnostic screening exam. They also reported that there was no statistically significant difference in the morphologic and enhancement MR imaging features of the cancers in BRCA1 and BRCA2 carriers.

They observed that the MR imaging features are typical of invasive cancers and show poorly defined, irregular or spiculated margins, have predominantly ring-like or heterogeneous enhancement patterns, and have type 2 or 3 enhancement curves.

The scientists noted that the MARIBS trial was limited to a small patient cohort and that MR technology—as well as image reformation technology—has improved greatly since the trial’s conclusion in 2003.

As a result of their analysis, the researchers said that when clinicians use MRI in screening high-risk women for breast cancer, small enhancing lesions may not exhibit classic malignant features and, thus, the threshold level for recommendation of a biopsy should be lowered.

“Our review of the images from prior MR imaging examinations shows that the cancers grow in size and that enhancement curves change from type 1 to type 2 or 3 and demonstrate greater signal enhancement over time,” the authors wrote. “In screening high risk women, it is essential to be vigilant about these small cancers and to maintain a high degree of suspicion.”
Last updated on August 7, 2009 at 9:45 am EST