title: Correlation of In Vivo and Ex Vivo ADC and T2 of In Situ and Invasive Murine Mammary Cancers.
abstract: Ex vivo MRI may aid in the evaluation of surgical specimens, and provide valuable information regarding the micro-anatomy of mammary/breast cancer. The use of ex vivo MRI to study mouse mammary cancer would be enhanced if there is a strong correlation between parameters derived from in vivo and ex vivo scans. Here, we report the correlation between apparent diffusion coefficient (ADC) and T2 values measured in vivo and ex vivo in mouse mammary glands with in situ cancers (mammary intraepithelial neoplasia (MIN)) and invasive cancers (those which spread outside the ducts into surrounding tissue). MRI experiments were performed on the Polyoma middle T oncoprotein breast cancer mouse model (n = 15) in a 9.4T scanner. For in vivo experiments, T2-weighted (T2W) images were acquired to identify abnormal regions, then ADC and T2 values were measured for nine selected slices. For ex vivo experiments, a midline incision was made along the spine, and then skin, glands, and tumors were gently peeled from the body. Tissue was fixed in formalin, placed around a mouse-sized sponge, and sutured together mimicking the geometry of the gland when attached to the mouse. The same pulse sequences used for in vivo experiments were repeated for ex vivo scans at room temperature. Regions of interest were manually traced on T2W images defining features that could be identified on in vivo and ex vivo images. The results demonstrate a strong positive correlations between in vivo and ex vivo invasive cancers for ADC (r = 0.89, p <0.0001) and T2 (r = 0.89, p <0.0001) values; and weak to moderate positive correlations between in vivo and ex vivo in situ cancers for ADC (r = 0.61, p <0.0001) and T2 (r = 0.79, p <0.0001) values. The average ex vivo ADC value was about 54% of the in vivo value; and the average ex vivo T2 was similar to the in vivo value for cancers. Although motion, fixation, and temperature differences affect ADC and T2, these results show a reliable relationship between ADC and T2 in vivo and ex vivo. As a result ex vivo images can provide valuable information with clinical and research applications.
authors.affiliation: Department of Radiology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Fan
authors.affiliation: Ben May Department for Cancer Research, The University of Chicago, 929 East 57th Street, Chicago, IL, 60637, United States of America.
authors.forename: Kay
authors.initials: K
authors.lastname: Macleod
authors.affiliation: Department of Radiology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Devkumar
authors.initials: D
authors.lastname: Mustafi
authors.affiliation: Medicine, Hematology/Oncology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Suzanne D
authors.initials: SD
authors.lastname: Conzen
authors.affiliation: Department of Radiology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Erica
authors.initials: E
authors.lastname: Markiewicz
authors.affiliation: Department of Radiology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Marta
authors.initials: M
authors.lastname: Zamora
authors.affiliation: Department of Radiology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Vosicky
authors.affiliation: Department of Pathology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Mueller
authors.affiliation: Department of Radiology, The University of Chicago, 5841 S. Maryland Avenue, Chicago, IL, 60637, United States of America.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Karczmar
mesh_terms: D000818:Animals; D002278:Carcinoma in Situ / Q000473:pathology*; D005260:Female; D008198:Lymph Nodes / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008321:Mammary Glands, Animal / Q000473:pathology*; D015674:Mammary Neoplasms, Animal / Q000473:pathology*; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009361:Neoplasm Invasiveness; D015203:Reproducibility of Results