Abstract
.Significance: Diffuse optical imaging (DOI) provides in vivo quantification of tissue chromophores such as oxy- and deoxyhemoglobin ( and HHb, respectively). These parameters have been shown to be useful for predicting neoadjuvant treatment response in breast cancer patients. However, most DOI devices designed for the breast are nonportable, making frequent longitudinal monitoring during treatment a challenge. Furthermore, hemodynamics related to the respiratory cycle are currently unexplored in the breast and may have prognostic value.Aim: To design, fabricate, and validate a high optode-density wearable continuous wave diffuse optical probe for the monitoring of breathing hemodynamics in breast tissue.Approach: The probe has a rigid-flex design with 16 dual-wavelength sources and 16 detectors. Performance was characterized on tissue-simulating phantoms, and validation was performed through flow phantom and cuff occlusion measurements. The breasts of healthy volunteers were measured while performing a breathing protocol.Results: The probe has 512 unique source–detector (S-D) pairs that span S-D separations of 10 to 54 mm. It exhibited good performance characteristics: drift of 0.34%/h, precision of 0.063%, and mean up to 41 mm S-D separation. Absorption contrast was detected in flow phantoms at depths exceeding 28 mm. A cuff occlusion measurement confirmed the ability of the probe to track expected hemodynamics in vivo. Breast measurements on healthy volunteers during paced breathing revealed median signal-to-motion artifact ratios ranging from 8.1 to 8.7 dB. Median and amplitudes ranged from 0.39 to and 0.08 to , respectively. Median oxygen saturations at the respiratory rate ranged from 82% to 87%.Conclusions: A wearable diffuse optical probe has been designed and fabricated for the measurement of breast tissue hemodynamics. This device is capable of quantifying breathing-related hemodynamics in healthy breast tissue.
Highlights
An estimated 84,000 new cases of locally advanced breast cancer (LABC) will be diagnosed in 2021.[1]
A wearable diffuse optical probe has been designed and fabricated for the measurement of breast tissue hemodynamics. This device is capable of quantifying breathing-related hemodynamics in healthy breast tissue
Diffuse optical imaging (DOI), commonly referred to as near-infrared spectroscopy, or NIRS, is a label-free, noninvasive, and relatively inexpensive functional imaging modality that has been explored as a method of predicting neoadjuvant chemotherapy (NAC) treatment response in the clinic
Summary
An estimated 84,000 new cases of locally advanced breast cancer (LABC) will be diagnosed in 2021 (this estimate refers to the number of projected “regional” breast cancer cases, which has significant overlap in definition with LABC).[1]. Many prior studies have utilized FD-DOI or TD-DOI to obtain absolute concentrations of HbO2, HHb, H2O, and lipid content at baseline and time points leading up to the midpoint of NAC.[7,8,9,10,11,12,13] These studies have generally found that decreases in HHb and H2O and an increase in lipid at various time points between 1 week and midpoint of chemotherapy (compared to baseline) are well correlated with a pathologic complete response (pCR). One of these studies even showed statistically significant optical contrast in HbO2 between responders and nonresponders as early as 1 day into chemotherapy.[9]
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