"Paul’s Perspicacity, Contrast Reagents and Cancer: MRI Breast Screening"

 Charles Springer, Professor and Director, Advanced. Imaging Research Center,
   Oregon Health & Science University

Mammography represents a great medical imaging triumph: it has saved millions of lives. However, there is growing concern over its continued large fraction of false positive readings. These lead to unnecessary biopsy/pathology procedures that entail pain, anxiety, and considerable expense. There is increasing advocacy to increase the fraction of breast screening by Dynamic-Contrast-Enhanced MRI (DCE MRI) – a technique that monitors the time-course of the passage of an injected dye (contrast reagent) through the tissue and tumor of interest. However, DCE-MRI has not yet demonstrated a sufficiently small false positive rate to become cost-effective compared with breast biopsy. Our research group and collaborators (at Memorial Sloan Kettering and Stony Brook) have discovered that the high DCE-MRI false positive rate results from a systematic error in the mathematical model used to analyze the pharmacokinetic time-course data. This is a failure to account for the kinetics of coupled chemical equilibria involved in the molecular mechanism of contrast reagent action. Our model, correcting for the consequent MR “shutter-speed” effects, yields no false positives or false negatives in a population that now includes 22 patients. That is, it completely discriminates malignant from benign tumors at an early stage.