Abstract 4702: Characterization of ultrasound and immunohistochemichal parameters during development of murine tumor

Background: We compared the evolution of US index in vivo (morphological tumor size, tissue elasticity and microvascular flow) with whole-slice fluorescent immunohistochemical marker maps at different stages of murine tumor development. Methods: Murine colorectal carcinoma (CT26) was subcutaneously implanted in 49 mice on Day 0 (D0). Mice were randomized for data acquisition on D7, D10, D14, D16 and D17 (n = 10 each day except for D16 n = 9). Tumors were measured in B-mode along major transverse and longitudinal axes to estimate ellipsoidal volume. Contrast-Enhanced Ultrasound (CEUS) performed with Sequoia 512, 7-14 MHz probe and with syringe-pump-controlled bolus injection in the caudal vein of 40 μL of SonoVue (Bracco Suisse) and Shear-Wave Elastography (SWE; SSI, Aixplorer, SL 15-4 probe) maps were acquired along the longitudinal axis. Whole-slice histological sections were prepared with fluorescent immunohistochemical staining and parametric maps were made with in-house software to estimate the % area of nuclei, apoptosis (AP) and vascular endothelium (VE) marker. Regions with no contrast-enhancement were identified to estimate % perfused area (%P) and to construct perfused (P) and nonperfused (NP) masks that were then co-registered to SWE maps. Mean and standard deviation (SD) of the SWE could be calculated in whole tumor, P and NP zones. Average contrast intensity vs time curves in the P zone were fit to a lognormal model to estimate Area Under the Curve (AUC), Peak Enhancement (PE), Time to Peak (TTP), Mean Transit Time (MTT), Wash In Rate (WIR) and Wash Out Rate (WOR). The non-parametric Wilcoxon rank and Spearman tests were used to test respectively parameter evolution and correlation. Results: SWE and CEUS parameters did not correlate. SWE did not differ significantly for P and NP zones. Only TTP (RS = 0.47, p = 75%) and did not correlate with tumor volume. Individual histological parameters did not change significantly with time or tumor volume, but % area of strong co-marking of VE and AP decreased significantly between D10 and D14/16. Conclusions: These preliminary results probe the relationship between tumor volume, functional-flow and elastic properties in tumors. One CEUS parameter correlated with tumor growth and thus appears to be sensitive to changes occurring during tumor development. Lack of correlation between SWE and CEUS parameters suggests that they provide complementary information. Nevertheless, it is better to understand the sensitivity of these non-invasive parameters to changes occurring during tumor development in order to obtain a predictive tumor growth parameter. The difference combination of these parameters will change the clinical practice, allowing an early therapeutic adaptation without loss of opportunity to take the good treatment for the patient and without unnecessary therapeutic costs. Citation Format: Jerome Griffon, Delphine Le Guillou-Buffello, Lori Bridal, Michele Lamuraglia. Characterization of ultrasound and immunohistochemichal parameters during development of murine tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4702.