Collagen quantification in breast tissue using a 12-wavelength near infrared spectral tomography (NIRST) system

Abstract

A portable near infrared spectral tomography (NIRST) system was adapted for breast cancer detection and treatment monitoring with improved speed of acquisition for parallel 12 wavelengths of parallel frequency-domain (FD) and continuous-wavelength (CW) measurement. Using a novel gain adjustment scheme in the Photomultiplier Tube detectors (PMTs), the data acquisition time for simultaneous acquisition involving three FD and three CW wavelengths, has been reduced from 90 to 55 seconds, while signal variation was also reduced from 2.1% to 1.1%. Tomographic images of breast collagen content have been recovered for the first time, and image reconstruction approaches with and without collagen content included have been validated in simulation studies and normal subject exams. Simulations indicate that including collagen content into the reconstruction procedure can significantly reduce the overestimation in total hemoglobin, water and lipid by 8.9M, 1.8% and 15.8%, respectively, and underestimates in oxygen saturation by 9.5%, given an average 10% background collagen content. A breast cancer patient with invasive ductal carcinoma was imaged and the reconstructed images show that the recovered tumor/background contrast in total hemoglobin increased from 1.5 to 1.7 when collagen was included in reconstruction.

Clinical Feasibility of Diffuse Optical Spectroscopic Imaging for Sarcoma

“…However, the spectra for myoglobin and hemoglobin are so similar they cannot be separated in this context (Chance et al, 1988). Collagen is also an important component in bone, tendon, cartilage, muscle, and skin (Lodish et al, ) and several groups have added collagen to their fitting procedures (Pifferi et al, 2004;Zhao et al, 2017;Taroni et al, 2007;Sekar et al, 2015a;Sekar et al, 2015b).…”

“…To increase the SNR, larger area APDs or photomultiplier tubes (PMTs) could be utilized, but each of these design choices involve tradeoffs. For example, larger area APDs generally have reduced modulation bandwidth, and PMTs have limited dynamic range and linear operating regions (Zhao et al, 2017).…”

Characterization of bony anatomic regions in pediatric and adult healthy volunteers using diffuse optical spectroscopic imaging

“… 49 Collagen was not included in part because this study only took measurements up to 1000 nm, and collagen extractions have been shown to benefit from longer wavelengths, which include the absorption peaks at 1025 and 1200 nm. 17 , 50 – 52 Additionally, there are limited experimental methods to validate the accuracy of collagen fits. It is likely that if collagen was included as a chromophore, the lipid, water, and deoxyhemoglobin concentrations reported here would decrease to some extent.…”

In vivo, noninvasive functional measurements of bone sarcoma using diffuse optical spectroscopic imaging

“…Collagen is also an important component in bone, tendon, cartilage, muscle, and skin, 57 and several groups have added collagen to their fitting procedures. [48][49][50]52,58 The use of collage as a contributing absorber is relatively recent, and there are limited experimental methods to validate the accuracy of collagen fits. For example, there are no known reports demonstrating the fabrication of tissue mimicking optical phantoms that incorporate collagen at physiologically relevant concentrations at the volume scales needed for diffuse optical measurements.…”

“…For example, larger areas APDs generally have reduced modulation bandwidth, and PMTs have limited dynamic range and linear operating regions. 58 Improvements to probe geometry and materials would also assist in measuring this patient population. For example, one subject (subject 1003) could not be measured because the tumor region was too tactile sensitive for a contact probe.…”