Article

Annals of Biomedical Engineering

, Volume 42, Issue 6, pp 1292-1304

First online:

Estimating Cell Concentration in Three-Dimensional Engineered Tissues Using High Frequency Quantitative Ultrasound

  • Karla P. MercadoAffiliated withDepartment of Biomedical Engineering, University of RochesterThe Rochester Center for Biomedical Ultrasound, University of Rochester
  • , María HelgueraAffiliated withThe Rochester Center for Biomedical Ultrasound, University of RochesterChester F. Carlson Center for Imaging Science, Rochester Institute of Technology
  • , Denise C. HockingAffiliated withDepartment of Biomedical Engineering, University of RochesterThe Rochester Center for Biomedical Ultrasound, University of RochesterDepartment of Pharmacology and Physiology, University of Rochester
  • , Diane DaleckiAffiliated withDepartment of Biomedical Engineering, University of RochesterThe Rochester Center for Biomedical Ultrasound, University of Rochester Email author 

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Abstract

Histology and biochemical assays are standard techniques for estimating cell concentration in engineered tissues. However, these techniques are destructive and cannot be used for longitudinal monitoring of engineered tissues during fabrication processes. The goal of this study was to develop high-frequency quantitative ultrasound techniques to nondestructively estimate cell concentration in three-dimensional (3-D) engineered tissue constructs. High-frequency ultrasound backscatter measurements were obtained from cell-embedded, 3-D agarose hydrogels. Two broadband single-element transducers (center frequencies of 30 and 38 MHz) were employed over the frequency range of 13–47 MHz. Agarose gels with cell concentrations ranging from 1 × 104 to 1 × 106 cells mL−1 were investigated. The integrated backscatter coefficient (IBC), a quantitative ultrasound spectral parameter, was calculated and used to estimate cell concentration. Accuracy and precision of this technique were analyzed by calculating the percent error and coefficient of variation of cell concentration estimates. The IBC increased linearly with increasing cell concentration. Axial and lateral dimensions of regions of interest that resulted in errors of less than 20% were determined. Images of cell concentration estimates were employed to visualize quantitatively regional differences in cell concentrations. This ultrasound technique provides the capability to rapidly quantify cell concentration within 3-D tissue constructs noninvasively and nondestructively.

Keywords

Ultrasound tissue characterization Integrated backscatter coefficient Nondestructive evaluation Parametric imaging Tissue engineering