We evaluate the performance of ODISsey<sup>TM</sup> Tissue Oximeter (ViOptix, Inc., Fremont, CA) against co-oximeter.
Concurrent oxygen saturation measurements were made in three dog limbs surgically removed and perfused with an
extracorporeal blood circulation system. Oxygen saturation was adjusted in steps ranging from 95% down to 5% as
monitored by the co-oximeter. The co-oximeter was used to measure the oxygen saturation of the whole blood drawn
from both the arterial and the venous ports of the limb. The tissue oxygenation measured by the ODISsey<sup>TM</sup> tissue
oximeter was compared with the average of the arterial and the venous blood oxygenation measured by the co-oximeter.
Linear correlation was observed between the average oxygenation given by the co-oximeter and the ODISseyTM readings,
with a root-mean-square difference of 7.6% and the correlation coefficient of 0.941, calculated from N = 194 data points.
We studied ischemia and reperfusion in island groin flaps for nine Charles River rats.
When the artery and/or vein are clamped, the oxygen saturation of hemoglobin
(StO2) measured by an infra-red spectroscopic device (ViOptix, Inc., Fremont, CA)
dropped significantly. The drop in arterial occlusion was usually faster than that in
venous occlusion. When the clamp was released after more than 1 hour of vessel
occlusion, the StO2 value came back, typically not to the pre-occlusive level but only
about half of it.
We report results of clinical trials on flap monitoring in 65 plastic surgeries. Hemoglobin oxygen saturation of flap tissue (StO<sub>2</sub>) was monitored non-invasively by using ODISsey<sup>TM</sup> tissue oximeter, an infrared spectroscopic device. StO<sub>2</sub> measurements were conducted both intra-operatively and post-operatively. From the intra-operative measurements, we observed that StO<sub>2</sub> values dropped when the main blood vessels supplying the flap were clamped in surgery, and that StO<sub>2</sub> jumped after anastomosis to a value close to its pre-operative value. From post-operative monitoring measurements for the 65 flap cases, each lasted two days or so, we found that the StO<sub>2</sub> values approach to a level close to the baseline if the surgery was successful, and that the StO<sub>2</sub> value dropped to a value below 30% if there is a perfusion compromise, such as vascular thrombosis.
It is well known that the relation between the partial pressure of oxygen in blood (PO<sub>2</sub>) and the hemoglobin oxygen saturation in blood (SO<sub>2</sub>) is given by the oxyhemoglobin dissociation curve. In this study, we investigate if a similar relation exists in tissue. The PO<sub>2</sub> in tissue was approximated by the transcutaneous partial pressure of oxygen (TcPO<sub>2</sub>) measured by TCM3<sup>TM</sup> Transcutanous pO<sub>2</sub>/pCO<sub>2</sub> Monitoring System; and the SO<sub>2</sub> in tissue (StO<sub>2</sub>) was measured by ODISsey<sup>TM</sup> Tissue Oximeter. The study showed that the TcPO<sub>2</sub> versus StO<sub>2</sub> relation is similar to the dissociation curve in blood, as expected.
For characterization of suspicious breast lesions, we used a dual modal imaging scheme integrating a hand-held near infrared imager and a portable ultrasound probe. The functional properties of the suspicious lesion and the surrounding tissue were reconstructed based on the diffuse reflectance measurement of the near infrared light and the ultrasound measurement of the tumor morphology. The near infrared/ultrasound dual modal imaging system has been validated through a series of bench top tests where tumor simulators with various absorptions were embedded at different depth in a liquid tissue-simulating phantom. The clinical trial of the imaging scheme was conducted on 44 subjects with suspicious breast lesions identified by mammography and/or ultrasound. Both near infrared and ultrasound data were collected from the area of the suspicious breast lesion and from the adjacent reference breast tissue. The clinical trial demonstrates that the dual modal imaging system can reach up to 71% of diagnostic sensitivity and 58% of specificity in detecting breast carcinoma. This may indicate that the system could potentially be used in breast cancer detection adjunctive with mammography.
Using a near-infrared optical device developed by ViOptix, Inc., a clinical study on post-operative non-invasive monitoring of finger blood perfusion has been conducted for 48 patients undergoing digital replantation at the California Pacific Medical Center. The study showed that non-survival digits have their tissue oxygen saturation (StO<sub>2</sub>) values significantly lower than those for the controls in general, but survival digits did not. Further, the StO<sub>2</sub> values can be used to define a survival index, in terms of which a digit survival criterion was tentatively suggested. Applying the criterion to the 64 digits (with 3 of them non-survival) involved in the clinical study, the sensitivity and the specificity were high. Therefore the device may have potential to be used in post-operative monitoring for digit replantation.
X-ray mammography has been the major imaging modality in breast cancer detection for years, despite its high false diagnosis rate for malignant tumors and harmful radiation. In the last decade, optical imaging has been emerging as a promising method for breast cancer detection. Using near infrared (NIR) light ranging from 690 nm to 900 nm, an optical device can measure functional properties of breast tissue, such as total hemoglobin concentration (HbT) and oxygen saturation (SO2). Cancers tend to have higher levels of HbT because of their greater vascularization, and lower SO2 because of greater oxygen consumption, than normal tissue. Thus the NIR technology could be useful in breast cancer detection. In addition, optical detection is totally noninvasive and safe, and can be low cost. Photonify Technologies Inc. has developed an optical device for real-time two-dimensional mapping of HbT and SO2 in breast tissue. The device has been tested in a pilot clinical study for a group of 50 patients at the Department of Radiology of the Masachusetts General Hospital at Harvard Medical School. Preliminary results suggest that contrast-normalized standard deviations in HbT and SO2 might be good indicators for breast cancer detection. A patient may have a higher risk to have cancer in a breast portion where the normalized standard deviation in either HbT or SO2 is greater than 0.3. We demonstrate 92% diagnostic sensitivity and 66% specificity in detecting ductal carcinoma, either invasive or in <i>situ</i>. The device may potentially be used as an adjunctive tool with mammography to reduce unnecessary biopsies.
We report results of a feasibility clinical evaluation of the near-infrared Photonify Tissue Spectrometer in detection of peripheral vascular disease (PVD). In the evaluation, using a blood pressured cuff, we measure changes in oxygen saturation (S<sub>t</sub>O<sub>2</sub>) during a temporary occlusion of blood inflow. We use the post-occlusive S<sub>t</sub>O<sub>2</sub> recovery rate and the time needed for 80% recovery as parameters to differentiate healthy subjects from subjects with PVD, and obtained high diagnostic accuracy in 19 subjects enrolled in the clinical evaluation. This may suggest that the tissue spectrometer could be useful in diagnosis of PVD.