The LUCA device: a multi-modal platform combining diffuse optics and ultrasound imaging for thyroid cancer screening

Abstract

We present the LUCA device, a multi-modal platform combining eight-wavelength near infrared time resolved spectroscopy, sixteen-channel diffuse correlation spectroscopy and a clinical ultrasound in a single device. By simultaneously measuring the tissue hemodynamics and performing ultrasound imaging, this platform aims to tackle the low specificity and sensitivity of the current thyroid cancer diagnosis techniques, improving the screening of thyroid nodules. Here, we show a detailed description of the device, components and modules. Furthermore, we show the device tests performed through well established protocols for phantom validation, and the performance assessment for in vivo. The characterization tests demonstrate that LUCA device is capable of performing high quality measurements, with a precision in determining in vivo tissue optical and dynamic properties of better than 3%, and a reproducibility of better than 10% after ultrasound-guided probe repositioning, even with low photon count-rates, making it suitable for a wide variety of clinical applications.

Fig. 1.

(a) Photo of the LUCA device, with all the modules. (b) Photo of the LUCA multi-modal optical-ultrasound probe, with a sketch of the probe nose showing the current geometrical disposition of the fiber tips: $x-y$ DCS source fibers; $z$ TRS source fiber, $m-n$ DCS detection fibers, $p-q$ TRS detection fibers. (c) Block diagram of the LUCA device modules and communication.

Fig. 2.

Cross-talk between TRS and DCS. (a) Absorption coefficient measured by TRS in thyroid and phantom with DCS ON and OFF. (b) Reduced scattering coefficient measured by TRS in thyroid and phantom with DCS ON and OFF. (c) Blood flow index measured by DCS in thyroid with TRS ON and OFF

Fig. 3.

DCS module phantom demonstration tests. (a) Photo of the experimental setup, with the LUCA probe fixed through a mechanical holder in vertical position over the liquid phantom box. (b) Stability of $D_B$ over long time test (approx. 17 hours), data reported for one detection channel. (c) Standard deviation of the reduced autocorrelation function ($g_2-1$), for all the 16 acquisition channels, over 17-hours stability test. (d) Measured $D_B$ for phantom with different glycerol concentrations, long source-detector separation. (e) Ratio of the measured $D_B$ for phantom with different glycerol concentration (i. e. different viscosity) and comparison with theory, long source-detector separation. (f) Precision ($CV$) of the measured $D_B$ for phantom with different glycerol concentration (i. e. different viscosity), long source-detector separation. Different colors represent solutions with different absorption coefficient (blue ${\mu }_a=0.1c{m}^{-1}$, red ${\mu }_a=0.2c{m}^{-1}$, green ${\mu }_a=0.3c{m}^{-1}$), while the displacement with respect to the vertical axis represents different reduced scattering coefficients (left displacement: ${\mu }_s^{\prime }=5c{m}^{-1}$, center: ${\mu }_s^{\prime }=10c{m}^{-1}$, right displacement: ${\mu }_s^{\prime }=15c{m}^{-1}$). (g), (h), and (i) same as (d), (e) and (f) but for short source-detector separation channel.

Fig. 4.

In vivo tests. (a) Set up for thyroid repeatability measurements. (b) US image acquired simultaneously with optical data: 1- thyroid right lobe; 2- carotid; 3- sternocleidomastoid muscle; 4- skin; 5- trachea. (c) DCS repeatability results in the right thyroid lobe (5 repetitions per day, 4 days of measurements). (d) TRS repeatability results in the right thyroid lobe, absorption coefficient (top) and reduced scattering coefficient (bottom).

Fig. 5.

Arm cuff occlusion demonstration test. Blood flow index ($BFi$) changes (left block) and oxy- and deoxy-hemoglobin change (right block)