Abstract 4159: Noninvasive measurement of murine glioblastoma in vivo with a benchtop ultrasound instrument

Abstract The purpose of this study was to evaluate a new in vivo approach for rapidly measuring tumor volumes in rodent models for glioblastoma (GBM). GBM is the most common primary brain tumor with <5% of patients surviving >5 years post diagnosis. These poor outcomes underscore the importance of researching new treatment options, and murine models play a vital role in this. Noninvasive measurements of murine GBM tumors are commonly performed using CT and MRI but these tools are costly and time-consuming to use. BLI can quickly detect the presence of GBM cells in vivo, but image data can be challenging to correlate to tumor volume. In this study we demonstrate the feasibility of imaging GBM in vivo through the intact mouse skull using a benchtop robotic ultrasound scanner. This approach could offer researchers a means to quickly size tumors in the murine brain noninvasively. To test feasibility of this approach, a female athymic nude mouse aged 16 weeks was implanted with 2e5 U87 GBM cells in the brain. The tumor was given 25 days to develop prior to ultrasound imaging. After imaging, the brain was harvested for ex vivo validation of tumor presence and volume. Imaging was performed using a Vega ultrasound system (Revvity, Waltham, MA, USA) with the mouse in supine position and fur removed from head with depilatory cream. In vivo imaging consisted of a contrast-enhanced acoustic angiography (AA) scan to assess tumor perfusion. An ex vivo B-mode scan of the brain was collected after sacrificing the animal to validate the location and size of the tumor without interference from the skull. The tumor volumes were measured in each image and compared. 3D segmentations in the ex vivo and in vivo images yielded volumes of 43.1 mm3 and 44.6 mm3, respectively, a 3.5% variance. In the in vivo AA image, the borders of the tumor were adequately well-defined for volume estimation, despite some shadowing from the sagittal suture of the skull. In the B-mode image of the excised brain, the tumor appeared hyperechoic compared to the contralateral hemisphere. Images were acquired in < 2 min. This pilot study demonstrates a potential alternative to CT and MRI for monitoring of GBM volumes in vivo. Citation Format: Thomas M. Kierski, Juan D. Rojas, Morrent Thang, Shawn D. Hingtgen, Phillip G. Durham, Paul A. Dayton, Tomek J. Czernuszewicz, Ryan C. Gessner. Noninvasive measurement of murine glioblastoma in vivo with a benchtop ultrasound instrument [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4159.