Abstract
Diffuse optical spectroscopy (DOS) has been used to monitor and predict the effects of neoadjuvant (i.e., presurgical) chemotherapy in breast cancer patients in several pilot studies. Because patients with suspected breast cancers undergo biopsy prior to treatment, it is important to understand how biopsy trauma influences DOS measurements in the breast. The goal of this study was to measure the effects of a standard core breast biopsy on DOS measurements of tissue deoxyhemoglobin, hemoglobin, water, and bulk lipid concentrations. We serially monitored postbiopsy effects in the breast tissue in a single subject (31-year-old premenopausal female) with a 37x18x20 mm fibroadenoma. A baseline measurement and eight weekly postbiopsy measurements were taken with a handheld DOS imaging instrument. Our instrument used frequency domain photon migration combined with broadband steady-state spectroscopy to characterize tissues via quantitative measurements of tissue absorption and reduced scattering coefficients from 650 to 1000 nm. The concentrations of significant near-infrared (NIR) absorbers were mapped within a 50 cm(2) area over the biopsied region. A 2-D image of a contrast function called the tissue optical index (TOI=deoxyhemoglobinxwaterbulk lipid) was generated and revealed that a minimum of 14 days postbiopsy was required to return TOI levels in the biopsied area to their prebiopsy levels. Changes in the TOI images of the fibroadenoma also reflected the progression of the patient's menstrual cycle. DOS could therefore be useful in evaluating both wound-healing response and the effects of hormone and hormonal therapies in vivo.
Highlights
1.1 Optical Monitoring of the Effects of Neoadjuvant ChemotherapyNeoadjuvant chemotherapy, or chemotherapy administered prior to the surgical removal of the tumor, is increasingly used for treatment of large (>2 cm) and locally advanced breast cancers. 1-3 Neoadjuvant chemotherapy offers two distinct advantages over conventional postsurgical chemotherapy
The lesion area is the optical property in question that is above a threshold of the tissue optical index (TOI) full width at half maximum (FWHM)
Individual response rates may vary with different patients, but the 2- to 3-week wound healing time frame is consistent with what has been reported by Hom. 23 The presence of bruises may prolong these effects, and our case study may not represent the full spectrum of possible healing responses
Summary
1.1 Optical Monitoring of the Effects of Neoadjuvant ChemotherapyNeoadjuvant chemotherapy, or chemotherapy administered prior to the surgical removal of the tumor, is increasingly used for treatment of large (>2 cm) and locally advanced breast cancers. 1-3 Neoadjuvant chemotherapy offers two distinct advantages over conventional postsurgical chemotherapy. Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) have been suggested as techniques that could monitor the physiological effects of neoadjuvant chemotherapy.[4,5,6,7,8] DOS is a noninvasive, bedside-capable technique that quantitatively measures near-infrared (NIR, 650 to 1000 nm) absorption and reduced scattering spectra.[9] Absorption spectra are used to calculate the tissue concentrations of oxygenated (ctO2Hb) and deoxygenated hemoglobin (ctHHb), water (ctH2Ob), and bulk lipid, which are the dominant NIR molecular absorbers in breast tissues. DOS samples a low number of spatial locations with a large spectral bandwidth. DOI typically samples a large number of spatial locations but with low spectral bandwidth. The relationship between DOS and DOI is comparable to that between magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI)
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