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.