Wearable near-infrared optical probe for continuous monitoring during breast cancer neoadjuvant chemotherapy infusions

Abstract

We present a new continuous-wave wearable diffuse optical probe aimed at investigating the hemodynamic response of locally advanced breast cancer patients during neoadjuvant chemotherapy infusions. The system consists of a flexible printed circuit board that supports an array of six dual wavelength surface-mount LED and photodiode pairs. The probe is encased in a soft silicone housing that conforms to natural breast shape. Probe performance was evaluated using tissue-simulating phantoms and in vivo normal volunteer measurements. High SNR (71 dB), low source-detector crosstalk ( ? 60 ?? dB ), high measurement precision (0.17%), and good thermal stability (0.22% V rms / ° C ) were achieved in phantom studies. A cuff occlusion experiment was performed on the forearm of a healthy volunteer to demonstrate the ability to track rapid hemodynamic changes. Proof-of-principle normal volunteer measurements were taken to demonstrate the ability to collect continuous in vivo breast measurements. This wearable probe is a first of its kind tool to explore prognostic hemodynamic changes during chemotherapy in breast cancer patients.

Fig. 1

(a) Flexible PCB and optical components. (b) Top and (c) bottom view of the wearable probe. (d) Flexibility of the probe under gentle pressure.

Fig. 2

Schematic view of CW DOI system. Solid line: electrical signal. Red arrow: optical signal.

Fig. 3

System drift test. Results are shown for (a) the 750-nm and (b) 850-nm optical channels. An average drift of 0.18% or less was observed over the 90-min test.

Fig. 4

System thermal response to local probe temperature changes. The red solid line corresponds to the local temperature measured at the probe, while the black solid line corresponds to the normalized changes in detector voltage levels. The shaded area indicates the standard derivation calculated from the optodes that share the same wavelength. The red dashed lines show the upper and lower bound of normal physiological temperature of human skin. (a) Thermal test $\mathrm{w}/750\mathrm{nm}$ LEDs and (b) thermal test $\mathrm{w}/850\mathrm{nm}$ LEDs.

Fig. 5

Probe results compared to a DO sensor for (a) oxygen saturation and (b) chromophore concentration changes measurements taken from a blood–intralipid phantom during phantom deoxygenation.

Fig. 6

(a) The probe is secured to the subject’s skin using IV tape during cuff occlusion measurements. (b) and (c) Hemodynamic response at forearm during cuff occlusion test.

Fig. 7

Hemodynamic fluctuations of healthy female breast tissue at resting state. (a) Oxyhemoglobin (${\mathrm{HbO}}_2$) and deoxyhemoglobin (HHb); (b) total hemoglobin (THb).