Investigation of Diagnostic Improvement Gained through Optimization of MR Methods for Breast Cancer Detection
- UT Southwestern-Other
Robert Lenkinski, Ph.D.
MRi of the breast is gaining widespread clinical acceptance, being used to screen high-risk women and to further investigate questionable ultra-sound or mammography findings. The observation of the local pattern of enhancement in dynamic contrast enhanced (DCe) imaging is the pillar of the MRi breast exams, yielding close to perfect lesion detection sensitivity. Less than ideal specificity, however, is exhibited by the current protocols; depending on the report, up to 4 out of 5 positive MRi exams result in negative biopsies and distraught patients. Methods to increase the specificity of the breast MRi exams are actively sought. Diffusion weighted imaging (DWi), which probes the mobility of the water molecules on scales of up to tens of microns, and which can result in the quantification of the apparent diffusion coefficient (aDC), is one of the front-runners in the race to increase breast MRi specificity. emerging studies performed at 1.5T point to the potential of DWi/aDC measurements to reduce up to 33% of the biopsies warranted by positive DCe results, without missing any cancers. as 3T scanners become the clinical standard, the extent of the improvement in specificity of breast cancer diagnosis that can be imparted to a DCe protocol by DWi/aDC measurements is yet to be determined. a number of problems associated with imaging the breast anatomy at high fields, such as image shading, artifacts due to Bo inhomogeneities, improper fat suppression, and the low channel count of breast RF receive coils available commercially, have left the 3T DWi spatial resolution in the 10-40 [MiCRo-SYMBoL]l range, similar to 1.5T, and significantly below the 1 [MiCRo-SYMBoL]l resolution typical of 3T DCe MRi protocols.
in a single MRi exam on a research scanner, each lesion will be categorized using the Bi-RaDS MRi score, which utilizes the DCe data alone, and then again using a modified Bi-RaDS score, which utilizes both DWi and DCe data. The sensitivity and specificity of each approach will be determined using pathology (biopsy results) as the gold standard.
Potential subjects will be identified by uTSW radiologists in the Breast Center when clinical indications suggest a mass that meets inclusion criteria. The physician will discuss the study with the potential subject, and if agreeable, a member of the research team will meet with the subject to further discuss participation and to obtain informed consent. except for eligibility screening by the treating physician, no study activities will be conducted prior to obtaining informed consent.
The results from biopsy will serve as the gold standard. Two radiologists, blinded from the biopsy results, will independently examine all the images in a random order. Results from both radiologists will be compared to the biopsy and the corresponding diagnoses will be calculated. The endpoints are:
1) The sensitivity and specificity of MRi tumor assessment with and without DWi/aDC inclusion in the protocol will be reported and compared.
2) The average values and variability of SnR and CnR for DWi images collected in this trial will be reported and applied to expected reproducibility of the results.
3) outcomes from subsets of images within a set of DWi images will be compared to assess the appropriateness of the selected b values in the protocol.
4) The variation of conductivity as measured by the MR method will be compared to the noise of the measurement.
Women with Breast Imaging-Reporting and Data System (BI-RADS) 4 or 5
Age >= 18 years
Ability to understand and the willingness to sign a written informed consent.