Near infrared imaging of tissue heterogeneity: probe design and sensitivity analysis

Development of a Smartphone-Based Optical Device to Measure Hemoglobin Concentration Changes for Remote Monitoring of Wounds

Telemedicine (TM) can revolutionize the impact of diabetic wound care management, along with tools for remote patient monitoring (RPM). There are no low-cost mobile RPM devices for TM technology to provide comprehensive (visual and physiological) clinical assessments. Here, a novel low-cost smartphone-based optical imaging device has been developed to provide physiological measurements of tissues in terms of hemoglobin concentration maps. The device (SmartPhone Oxygenation Tool—SPOT) constitutes an add-on optical module, a smartphone, and a custom app to automate data acquisition while syncing a multi-wavelength near-infrared light-emitting diode (LED) light source (690, 810, 830 nm). The optimal imaging conditions of the SPOT device were determined from signal-to-noise maps. A standard vascular occlusion test was performed in three control subjects to observe changes in hemoglobin concentration maps between rest, occlusion, and release time points on the dorsal of the hand. Hemoglobin concentration maps were compared with and without applying an image de-noising algorithm, single value decomposition. Statistical analysis demonstrated that the hemoglobin concentrations changed significantly across the three-time stamps. Ongoing efforts are in imaging diabetic foot ulcers using the SPOT device to assess its potential as a smart health device for physiological monitoring of wounds remotely.

Optical imaging for breast cancer prescreening

Breast cancer prescreening is carried out prior to the gold standard screening using X-ray mammography and/or ultrasound. Prescreening is typically carried out using clinical breast examination (CBE) or self-breast examinations (SBEs). Since CBE and SBE have high false-positive rates, there is a need for a low-cost, noninvasive, non-radiative, and portable imaging modality that can be used as a prescreening tool to complement CBE/SBE. This review focuses on the various hand-held optical imaging devices that have been developed and applied toward early-stage breast cancer detection or as a prescreening tool via phantom, in vivo, and breast cancer imaging studies. Apart from the various optical devices developed by different research groups, a wide-field fiber-free near-infrared optical scanner has been developed for transillumination-based breast imaging in our Optical Imaging Laboratory. Preliminary in vivo studies on normal breast tissues, with absorption-contrasted targets placed in the intramammary fold, detected targets as deep as 8.8 cm. Future work involves in vivo imaging studies on breast cancer subjects and comparison with the gold standard X-ray mammography approach.

US-guided diffused optical tomography: a promising functional imaging technique in breast lesions

OBJECTIVE

To investigate the feasibility and clinical efficacy of ultrasound (US)-guided diffused optical tomography (DOT) in differentiating malignant breast lesions from benign lesions.

MATERIAL AND METHODS

From October 2007 to August 2008, 198 women with 214 lesions scheduled for open biopsy were included in this study. Conventional US was used to locate the breast lesion, and DOT to measure the total haemoglobin concentration (THC) for each breast lesion. Sensitivity, specificity and overall accuracy were determined with surgical pathology as the gold standard.

RESULTS

There were 96 benign lesions and 118 malignant lesions. The total haemoglobin concentration (THC) of all 214 lesions was calculated from DOT. The average THC in benign lesions was 125.5 +/- 83.4 micromol/L, and in malignant lesions 222.2 +/- 87.2 micromol/L. The THC of malignant lesions was significantly higher than that of benign lesions (p < 0.05). When a THC of 140 micromol/L was used as the cutoff value for differentiating breast cancer from benign lesions, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of DOT were 83.9%, 66.7%, 76.2%, 75.6% and 77.1%, respectively. Our study demonstrated that THC was significantly higher in malignant lesions than in benign lesions.

CONCLUSION

US-guided diffused optical tomography, a noninvasive functional imaging technique, has potential utility in differentiating breast cancer from benign lesions.