Objective determination of peripheral edema in heart failure patients using short-wave infrared molecular chemical imaging

Abstract

. Significance : Peripheral pitting edema is a clinician-administered measure for grading edema. Peripheral edema is graded 0, , , , or , but subjectivity is a major limitation of this technique. A pilot clinical study for short-wave infrared (SWIR) molecular chemical imaging (MCI) effectiveness as an objective, non-contact quantitative peripheral edema measure is underway. Aim : We explore if SWIR MCI can differentiate populations with and without peripheral edema. Further, we evaluate the technology for correctly stratifying subjects with peripheral edema. Approach : SWIR MCI of shins from healthy subjects and heart failure (HF) patients was performed. Partial least squares discriminant analysis (PLS-DA) was used to discriminate the two populations. PLS regression (PLSR) was applied to assess the ability of MCI to grade edema. Results : Average spectra from edema exhibited higher water absorption than non-edema spectra. SWIR MCI differentiated healthy volunteers from a population representing all pitting edema grades with 97.1% accuracy ( shins). Additionally, SWIR MCI correctly classified shin pitting edema levels in patients with 81.6% accuracy. Conclusions : Our study successfully achieved the two primary endpoints. Application of SWIR MCI to monitor patients while actively receiving HF treatment is necessary to validate SWIR MCI as an HF monitoring technology.

Shortwave infrared spatial frequency domain imaging for non-invasive measurement of tissue and blood optical properties

“…[3][4][5] Reflectance imaging in the SWIR optical window has been explored for determination of peripheral edema, skin burn, and bruise imaging, but the planar reflectance data cannot reliably predict the optical properties of the tissue. [6][7][8] Techniques such as diffuse optical spectroscopy and spatial frequency domain imaging (SFDI) are widely used to measure tissue optical properties in the NIR region, namely, the absorption coefficient (μ a ) and the reduced scattering coefficient (μ 0 s ). SFDI measurements in the SWIR may be advantageous over other SWIR imaging techniques owing to its ability for quantitative assessment of tissue and blood optical properties.…”

Non-Contact Molecular Chemical Imaging Assessment of Tissue Congestion: A Validation Study Compared to MRI

“…CardioVere (CV) is a non-invasive, non-contact, optical device that uses SWIR MCI to measure the water content of living tissues. 20 Figure 2A shows the imaging system and major components, and Figure 2B, the SWIR MCI workflow. 20 Briefly, MCI integrates digital imaging with spectroscopy to provide both spatial and molecular information about a sample.…”

“…20 Figure 2A shows the imaging system and major components, and Figure 2B, the SWIR MCI workflow. 20 Briefly, MCI integrates digital imaging with spectroscopy to provide both spatial and molecular information about a sample. The technology illuminates the subject’s shin with broad-band white light and acquires a hypercube which contains a collection of high-definition, reflected light, wavelength-resolved images in 5 nm increments over the SWIR spectral range (wavelengths: 900 – 1700 nm).…”

Monitoring the skin structure during edema in vivo with spatially resolved diffuse reflectance spectroscopy

“…For instance, during heart failure, 1 physical examination using the “pitting scale” and weighing the patient remains the most useful approaches for assessing edematous syndrome; however, these methods are subjective and insufficient. 2 Assessment of water and lipids content in breast cancer tissues can provide important information about the characteristics of a tumor, 3 as the high water content in a tumor indicates edema and increased cellularity. 4 , 5 Likewise, the measurement of hydration in different skin layers is interesting for dermatology and cosmetology: 6 for instance, water content in the dermis is a marker of changes in the elastic properties of the skin, 7 and hydration of the stratum corneum is indicative of its barrier function.…”

“…3,12,13 For instance, in heart failure patients, peripheral edema was analyzed with short-wave NIR imaging. 2 Cutaneous edema induced by histamine application was studied with diffuse reflectance spectroscopy (DRS), 9,14 Raman fiber probe, 9 and multispectral NIR imaging. 2,9,15 The question of choosing the optimal distances between the source and the detector for leg edema evaluation were discussed in Nanjo et al 14 Since the optical and morphological properties of the skin differ significantly, 16 the assessment of hydration and cutaneous edema of the skin by optical methods is a complicated task.…”