Orthotopic Versus Allotopic Implantation: Comparison of Radiological and Pathological Characteristics

Abstract

Background: In experimental animal models, implantation location might influence the heterogeneity and overall development of the tumor, leading to an interpretation bias. Purpose: To investigate the effects of implantation location in experimental tumor model using magnetic resonance imaging (MRI) and pathological findings. Study Type: Prospective. Subjects: Forty-five breast cancer-bearing mice underwent orthotopic (N = 15) and heterotopic (intrahepatic [N = 15] and subcutaneous [N = 15]) implantation. Field Strength/Sequence: Sequences including: T1-weighted turbo spin echo sequence, T2-weighted blade sequence, diffusion-weighted imaging, pre-and post-contrast T1 mapping, multi-echo T2 mapping at 3.0 T. Assessment: MRI was performed at 7, 14, and 21 days after implantation. Native T1, post-contrast T1, T2, and apparent diffusion coefficient (ADC) of tumors, the tumor volume and necrosis volume within tumor were obtained. Lymphocyte cells from H&E staining, Ki67-positive, and CD31-positive cells from immunohistochemistry were determined. Statistical Tests: One-way analysis of variance and Spearman's rank correlation were performed. P value <0.05 was considered statistically significant.