Predicting Upgrade of Ductal Carcinoma In Situ to Invasive Breast Cancer at Surgery With Ultrafast Imaging

BACKGROUND. Biopsy-proven ductal carcinoma in situ (DCIS) lesions are often upgraded to invasive cancer at surgery. Therefore, accurate prediction of the likelihood of invasion is helpful for surgical planning, including the need for sentinel lymph node biopsy (SLNB). OBJECTIVE. The purpose of the present study was to investigate whether kinetic features of clinically available ultrafast MRI (UF-MRI) can predict upgrade of biopsy-proven DCIS to invasive cancer at surgical excision. METHODS. Consecutive patients with biopsy-proven pure DCIS lesions who underwent UF-MRI with conventional dynamic contrast-enhanced MRI (DCE-MRI) and subsequently underwent surgery between August 2019 and January 2021 were identified. Patient and lesion characteristics, biopsy method and pathology, and lesion features on mammography, ultrasound, DCE-MRI, and UF-MRI were assessed to determine predictors of upgrade to invasive cancer. The Fisher exact test and Kruskal-Wallis test were used for association analysis. RESULTS. In 68 patients (median age, 52.0 years; range, 31-79 years) with 68 biopsy-proven pure DCIS lesions, 26 lesions (38%) were upgraded from in situ to invasive cancer. An upgrade of DCIS to invasive cancer was significantly associated with a shorter time to enhancement (TTE) on preoperative UF-MRI (p = .03), with a threshold of 11 seconds providing maximum specificity (50%) and sensitivity (76%) for upgrade. Larger lesion size on DCE-MRI (p = .001) and mammography (p = .04) was also significantly associated with upgrade; an optimal predictive threshold of 4.4 cm on DCE-MRI yielded sensitivity of 88% and specificity of 56%. No other specific variables were significantly associated with upgrade after surgery. Logistic regression of selected features combined with TTE produced a higher AUC (0.85) in predicting upgrade to invasive disease than did each factor alone, but this result was not statistically significant. CONCLUSION. Preoperative UF-MRI TTE and lesion size on DCE-MRI and mammography show potential in predicting upgrade of DCIS to invasive cancer at surgery. CLINICAL IMPACT. UF-MRI provides useful information that can be used in surgical planning, including determination of the need to perform SLNB.