MRI shown to be better at detecting bc before it becomes invasive

[Lani]

especially high-grade DCIS which is often her2+ and felt to be a precursor
often of her2+ bc

Using MRI for Diagnosis Could Help Prevent Breast Cancer Progression [Doctor's Guide]
LONDON, U.K. — August 10, 2007 — Using magnetic resonance imaging (MRI) to diagnose breast cancer in its intraductal stage could help prevent the development of invasive cancer, conclude authors of an Article in this week's edition of The Lancet.
And an accompanying Comment says that the findings show that MRI should now be used as a distinct method in its own right to detect breast cancer in its earliest stage.
Professor Christiane Kuhl, Department of Radiology, University of Bonn, Germany and colleagues studied 7319 women over a 5-year period who had been referred to an academic breast centre. The women received MRI in addition to conventional mammography for diagnostic assessment and screening, with the aim of discovering the sensitivity of each method for diagnosing ductal carcinoma in situ (DCIS). Mammograms and MRI scans were then assessed independently by different radiologists, and the relative sensitivity of each method of detection was assessed by comparing the biological profiles of mammography-detected DCIS with those of MRI-detected DCIS.
The researchers found that of 167 women who had a diagnosis of DCIS, 153 (92%) were diagnosed by MRI compared with 93 (56%) diagnosed by mammography. Whereas the sensitivity of MRI for diagnosing DCIS increased with nuclear grade, that of mammography decreased. Of 89 women diagnosed with "high grade" DCIS, 87 (98%) were diagnosed by MRI, but only 46 (52%) by mammography. Accordingly, almost half (48%) were missed by mammography but diagnosed by MRI alone.
They also found that age, menopausal status, personal or family history of breast cancer, and breast density of women with MRI-only diagnosed disease did not differ significantly from those of women with mammography-diagnosed DCIS. The higher sensitivity of MRI was not associated with an unduly high number of false positive diagnoses — the positive predictive value of both methods was comparable, with 55% for mammography, and 59% for MRI.
The authors conclude: "Our study suggests that the sensitivity of film screen or digital mammography for diagnosing DCIS is limited.MRI could help improve the ability to diagnose DCIS, especially DCIS with high nuclear grade."

and here is the abstract:

MRI for diagnosis of pure ductal carcinoma in situ: a prospective observational study [The Lancet (UK)]
Background: Diagnosing breast cancer in its intraductal stage might be helpful to prevent the development of invasive cancer. Our aim was to investigate the sensitivity with which ductal carcinoma in situ (DCIS) is diagnosed by mammography and by breast MRI.
Methods: During a 5-year period, 7319 women who were referred to an academic national breast centre received MRI in addition to mammography for diagnostic assessment and screening. Mammograms and breast MRI studies were assessed independently by different radiologists. We investigated the sensitivity of each method of detection and compared the biological profiles of mammography-diagnosed DCIS versus DCIS detected by MRI alone. We also compared the risk profiles of women with mammography-detected DCIS with those of MRI-detected DCIS.
Findings: 193 women received a final surgical pathology diagnosis of pure DCIS. Of those, 167 had undergone both imaging tests preoperatively. 93 (56%) of these cases were diagnosed by mammography and 153 (92%) by MRI (p<0·0001). Of the 89 high-grade DCIS, 43 (48%) were missed by mammography, but diagnosed by MRI alone; all 43 cases missed by mammography were detected by MRI. By contrast, MRI detected 87 (98%) of these lesions; the two cases missed by MRI were detected by mammography. Age, menopausal status, personal or family history of breast cancer or of benign breast disease, and breast density of women with MRI-only diagnosed DCIS did not differ significantly from those of women with mammography-diagnosed DCIS.
Interpretation: MRI could help improve the ability to diagnose DCIS, especially DCIS with high nuclear grade.