A New Methodology for the Assessment of Very Low Concentrations of Cells in Serous Body Fluids Based on the Count of Ultrasound Echoes Backscattered From Cells

Evaluation of the Cell Concentration in Suspensions of Human Leukocytes by Ultrasound Imaging: The Influence of Size Dispersion and Cell Type

“…The methodology to assess cell concentration from ultrasound images followed in the present paper is based on the models proposed by Elvira et al [ 17 ], Fernández et al [ 18 ], and Fernández [ 19 ]. The first model detects and quantifies patterns of ultrasound echoes coming from individual scatterers [ 17 , 19 ].…”

“…The methodology to assess cell concentration from ultrasound images followed in the present paper is based on the models proposed by Elvira et al [ 17 ], Fernández et al [ 18 ], and Fernández [ 19 ]. The first model detects and quantifies patterns of ultrasound echoes coming from individual scatterers [ 17 , 19 ]. The algorithm needs to be tuned to the ultrasound device and configuration used, which is achieved by means of empirical calibration or numerical simulation.…”

“…Field simulations are used to obtain the relation between the μ parameter and the absolute concentration, since such relation depends on the ultrasound device and the pulse configuration used. These simulations were performed in MATLAB using the frequency domain model proposed in [ 17 , 19 ]. Once the relation between the μ parameter and the absolute concentration is obtained, the method is independent of the signal amplitude reaching the scatterers, which makes it suitable for analysing in vivo images.…”

“…Assuming Rayleigh scattering conditions (weakly scattering particles and particle sizes smaller than the wavelength [ 8 ]), both the quantification of cell echo patterns and the envelope statistics models do not depend on the particular size of the cells in monodisperse suspensions. However, it was shown [ 17 , 18 , 19 ] that the size dispersion may have an impact on the estimates provided by the algorithms and, as a consequence, corrections from these effects should be included in the models. To this end, the following methodology was followed in the present work: The size distribution of different types of leukocytes (lymphocytes and granulocytes) was characterized by optical microscopy.…”

“…Lee et al [ 16 ] proposed a technique which was successfully applied to T-cells suspensions in the range of 1–20 cells/μL, and to silica and polystyrene (PS) microparticles (10 and 15 μm diameter) in the range of 1–200 part/μL. Elvira et al [ 17 ] proposed a method based on the detection and quantification of ultrasound echo patterns from scatterers (EPQ) which was applied under poor signal to noise ratio (SNR) conditions to PS microparticles (7 μm and 12 μm diameter) in the 5–100 part/μL range. Fernández et al [ 18 ] used another algorithm based on signal envelope statistics analysis (ES) to assess the concentration of PS microparticles (7 μm and 12 μm diameter) in a wider range of 5–3000 part/μL.…”