Assessing reproducibility of diffusion-weighted magnetic resonance imaging studies in a murine model of HER2 + breast cancer

• Published in: Magnetic resonance imaging 2014-04, Vol.32 (3), p.245-249
• Main Authors: Whisenant, Jennifer G, Ayers, Gregory D, Loveless, Mary E, Barnes, Stephanie L, Colvin, Daniel C, Yankeelov, Thomas E
• Format: Article
• Language: English
• Subjects: Animals; Apparent diffusion coefficient; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cell Line, Tumor; Diffusion Magnetic Resonance Imaging - methods; Diffusion-weighted MRI; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Mice; Mice, Nude; Mouse; Radiology; Receptor, ErbB-2 - metabolism; Reproducibility; Reproducibility of Results; Sensitivity and Specificity
• ISSN: 0730-725X; 1873-5894
• DOI: 10.1016/j.mri.2013.10.013

Abstract Background and purpose The use of diffusion-weighted magnetic resonance imaging (DW-MRI) as a surrogate biomarker of response in preclinical studies is increasing. However, before a biomarker can be reliably employed to assess treatment response, the reproducibility of the technique must be established. There is a paucity of literature that quantifies the reproducibility of DW-MRI in preclinical studies; thus, the purpose of this study was to investigate DW-MRI reproducibility in a murine model of HER2 + breast cancer. Materials and methods Test–Retest DW-MRI scans separated by approximately six hours were acquired from eleven athymic female mice with HER2 + xenografts using a pulsed gradient spin echo diffusion-weighted sequence with three b values [150, 500, and 800 s/mm2 ]. Reproducibility was assessed for the mean apparent diffusion coefficient (ADC) from tumor and muscle tissue regions. Results The threshold to reflect a change in tumor physiology in a cohort of mice is defined by the 95% confidence interval (CI), which was ± 0.0972 × 10 - 3 mm2 /s (± 11.8%) for mean tumor ADC. The repeatability coefficient defines this threshold for an individual mouse, which was ± 0.273 × 10 - 3 mm2 /s. The 95% CI and repeatability coefficient for mean ADC of muscle tissue were ± 0.0949 × 10 - 3 mm2 /s (± 8.30%) and ± 0.266 × 10 - 3 mm2 /s, respectively. Conclusions Mean ADC of tumors is reproducible and appropriate for detecting treatment-induced changes on both an individual and mouse cohort basis.