Yicun Wang1, Qi Shao2, Pierre-Francois Van de Moortele3, Emilian Racila4, Jiaen Liu1,5, John Bischof1,2, Bin He1,6. 1. Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota. 2. Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota. 3. Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota. 4. Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota. 5. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland. 6. Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania.
Abstract
PURPOSES: To develop and evaluate a boundary informed electrical properties tomography (BIEPT) technique for high-resolution imaging of tumor electrical properties (EPs) heterogeneity on a rodent tumor xenograft model. METHODS: Tumor EP distributions were inferred from a reference area external to the tumor, as well as internal EP spatial variations derived from a plurality of relative transmit B1 measurements at 7T. Edge sparsity constraint was enforced to enhance numerical stability. Phantom experiments were performed to determine the imaging accuracy and sensitivity for structures of various EP values, as well as geometrical sizes down to 1.5 mm. Numerical simulation of a realistic rodent model was used to quantify the algorithm performance in the presence of noise. Eleven athymic rats with human breast cancer xenograft were imaged in vivo, and representative pathological samples were acquired for comparison. RESULTS: Reconstructed EPs of the phantoms correspond well to the ground truth acquired from dielectric probe measurements, with the smallest structure reliably detectable being 3 mm. EPs heterogeneity inside a tumor is successfully retrieved in both simulated and experimental cases. In vivo tumor imaging results demonstrate similar local features and spatial patterns to anatomical MRI and pathological slides. The imaged conductivity of necrotic tissue is higher than that of viable tissues, which agrees with our expectation. CONCLUSION: BIEPT enables robust detection of tumor EPs heterogeneity with high accuracy and sensitivity to small structures. The retrieved quantitative EPs reflect tumor pathological features (e.g., necrosis). These results provide strong rationale to further expand BIEPT studies toward pathological conditions where EPs may yield valuable, non-invasive biomarkers.
PURPOSES: To develop and evaluate a boundary informed electrical properties tomography (BIEPT) technique for high-resolution imaging of tumor electrical properties (EPs) heterogeneity on a rodent tumor xenograft model. METHODS:Tumor EP distributions were inferred from a reference area external to the tumor, as well as internal EP spatial variations derived from a plurality of relative transmit B1 measurements at 7T. Edge sparsity constraint was enforced to enhance numerical stability. Phantom experiments were performed to determine the imaging accuracy and sensitivity for structures of various EP values, as well as geometrical sizes down to 1.5 mm. Numerical simulation of a realistic rodent model was used to quantify the algorithm performance in the presence of noise. Eleven athymic rats with humanbreast cancer xenograft were imaged in vivo, and representative pathological samples were acquired for comparison. RESULTS: Reconstructed EPs of the phantoms correspond well to the ground truth acquired from dielectric probe measurements, with the smallest structure reliably detectable being 3 mm. EPs heterogeneity inside a tumor is successfully retrieved in both simulated and experimental cases. In vivo tumor imaging results demonstrate similar local features and spatial patterns to anatomical MRI and pathological slides. The imaged conductivity of necrotic tissue is higher than that of viable tissues, which agrees with our expectation. CONCLUSION: BIEPT enables robust detection of tumorEPs heterogeneity with high accuracy and sensitivity to small structures. The retrieved quantitative EPs reflect tumor pathological features (e.g., necrosis). These results provide strong rationale to further expand BIEPT studies toward pathological conditions where EPs may yield valuable, non-invasive biomarkers.
Authors: Astrid L H M W van Lier; David O Brunner; Klaas P Pruessmann; Dennis W J Klomp; Peter R Luijten; Jan J W Lagendijk; Cornelis A T van den Berg Journal: Magn Reson Med Date: 2011-06-27 Impact factor: 4.668
Authors: Ghoncheh Amouzandeh; Frederic Mentink-Vigier; Shannon Helsper; F Andrew Bagdasarian; Jens T Rosenberg; Samuel C Grant Journal: Phys Med Biol Date: 2020-02-28 Impact factor: 3.609