AR: Small MR-detected breast masses should be scrutinized
The malignancy rate for MR-detected breast masses less than or equal to 5 mm has been shown to be greater than 20 percent, indicating that these small masses should be viewed with a high degree of suspicion when seen in staging breast MRI exams, according to a study published in the January issue of Academic Radiology.
Sughra Raza, MD, of the department of radiology at Brigham and Women’s Hospital in Boston, and colleagues explained that the American College of Radiology Breast Imaging Reporting and Data System defines a “focus” as a dot of enhancement that is too small for further characterization. Generally smaller than 5 mm, these foci can present a problem for breast imagers.
“Although in some cases a focus may be a solitary finding, the appearance of multiple foci can be a manifestation of physiologic background parenchymal enhancement,” wrote the authors. “In such cases, distinguishing a small mass (characterizable shape and margins) within this background can be challenging.”
The authors wanted to determine the malignancy rate among biopsied MR-detected masses less than or equal to 5 mm, and also correlate imaging characteristics with pathology.
A retrospective review of 565 lesions biopsied between March 2004 and February 2009 found 68 lesions less than or equal to 5 mm. Study radiologists reviewed MR exams of lesions that were recommended for biopsy based on clinical setting, suspicious lesion morphology and kinetics.
Results showed that 20.6 percent of the masses 5 mm in size or smaller were malignant. Of the 32 masses that were less than 5 mm only, 28.1 percent were malignant.
Fifty percent of the malignancies were in patients with recently diagnosed breast cancer. Among this subset, two-thirds of the malignancies were in the same quadrant as the recently diagnosed breast cancer, and a high likelihood of malignancy based on proximity to known cancer was statistically significant, according to the authors.
No significant difference in malignancy was found based on age, T2-weighted signal, morphology or kinetics.
“In the face of multiple foci that may represent background parenchymal enhancement, the breast imager must keep a high index of suspicion and take into consideration not only unique suspicious features of any one of the multiple enhancing foci, but also consider the clinical setting, patient’s risk level and any pertinent findings on mammography and or ultrasound in order to make final recommendations,” wrote the authors.
Raza et al acknowledged speculation as to the benefit of further improvement of MRI resolution with higher magnet strengths, but said this benefit is limited by the fact that detecting small breast cancers on MRI depends on tumor neo-angiogenesis. The minimum tumor size at which abnormal enhancement is reliably detected is unclear, according to the authors.
Sughra Raza, MD, of the department of radiology at Brigham and Women’s Hospital in Boston, and colleagues explained that the American College of Radiology Breast Imaging Reporting and Data System defines a “focus” as a dot of enhancement that is too small for further characterization. Generally smaller than 5 mm, these foci can present a problem for breast imagers.
“Although in some cases a focus may be a solitary finding, the appearance of multiple foci can be a manifestation of physiologic background parenchymal enhancement,” wrote the authors. “In such cases, distinguishing a small mass (characterizable shape and margins) within this background can be challenging.”
The authors wanted to determine the malignancy rate among biopsied MR-detected masses less than or equal to 5 mm, and also correlate imaging characteristics with pathology.
A retrospective review of 565 lesions biopsied between March 2004 and February 2009 found 68 lesions less than or equal to 5 mm. Study radiologists reviewed MR exams of lesions that were recommended for biopsy based on clinical setting, suspicious lesion morphology and kinetics.
Results showed that 20.6 percent of the masses 5 mm in size or smaller were malignant. Of the 32 masses that were less than 5 mm only, 28.1 percent were malignant.
Fifty percent of the malignancies were in patients with recently diagnosed breast cancer. Among this subset, two-thirds of the malignancies were in the same quadrant as the recently diagnosed breast cancer, and a high likelihood of malignancy based on proximity to known cancer was statistically significant, according to the authors.
No significant difference in malignancy was found based on age, T2-weighted signal, morphology or kinetics.
“In the face of multiple foci that may represent background parenchymal enhancement, the breast imager must keep a high index of suspicion and take into consideration not only unique suspicious features of any one of the multiple enhancing foci, but also consider the clinical setting, patient’s risk level and any pertinent findings on mammography and or ultrasound in order to make final recommendations,” wrote the authors.
Raza et al acknowledged speculation as to the benefit of further improvement of MRI resolution with higher magnet strengths, but said this benefit is limited by the fact that detecting small breast cancers on MRI depends on tumor neo-angiogenesis. The minimum tumor size at which abnormal enhancement is reliably detected is unclear, according to the authors.
Evan Godt, Writer
Evan joined TriMed in 2011, writing primarily for Health Imaging. Prior to diving into medical journalism, Evan worked for the Nine Network of Public Media in St. Louis. He also has worked in public relations and education. Evan studied journalism at the University of Missouri, with an emphasis on broadcast media.