K Calculation Using Reference Method Corrected Native T for Breast Cancer Diagnosis.

Purpose: The objective of the study is to use multiple tube phantoms to generate correction factor at different spatial locations for each breast coil cuff to correct the native T value in the corresponding spatial location of the breast lesion. The corrected T value was used to compute K and analyze its diagnostic accuracy in the classification of target condition, i.e., breast tumors into malignant and benign.

Materials And Methods: Both phantom study (external reference) and patient's studies were acquired on simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) Biograph molecular magnetic resonance (mMR) system using 4 channel mMR breast coil. The spatial correction factors derived using multiple tube phantom were used for a retrospective analysis of dynamic contrast-enhanced (DCE) MRI data of 39 patients with a mean age of 50 years (31-77 years) having 51 enhancing breast lesions.

Results: Corrected and non-corrected receiver operating characteristic (ROC) curve analysis revealed a mean K value of 0.64 min and 0.60 min, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy for non-corrected data were 86.21%, 81.82%, 86.20%, 81.81%, and 84.31%, respectively, and for corrected data were 93.10%, 86.36%, 90%, 90.47%, and 90.20% respectively. The area under curve (AUC) of corrected data was improved to 0.959 (95% confidence interval [CI] 0.862-0.994) from 0.824 (95% CI 0.694-0.918) of non-corrected data, and for NPV, it was improved to 90.47% from 81.81%, respectively.

Conclusion: T values were normalized using multiple tube phantom which was used for computation of K. We found significant improvement in the diagnostic accuracy of corrected K values that results in better characterization of breast lesions.