This study compared the transcutaneous target level irradiances from the thoracic to lumbar segments of the interior spinal canal in three cadaver dogs, measured for light at four wavelengths (808 nm, 915 nm, 975 nm, and 1064 nm), common in photobiomodulation therapy (PBMT). Intra-spinal irradiances at nine sites spanning approximately 8 cm in length were measured using a flexible intra-spinal probe under surface application of continuous-wave (CW) light with powers ranging from 0.5 W to 2 W. Surface illumination was applied using an acupuncture treatment head in three modes: non-contact with skin removed, non-contact with skin intact, and contact with skin intact. During surface application, the treatment head was positioned over the spinal canal near the 13th vertebrae (T13, surface site 1), and approximately 4 cm (surface site 5) and 8 cm (surface site 9) caudal to T13. At each position of the treatment head, the light was multiplexed among the four wavelengths at the same power setting. In all three modes of surface application, the target level irradiance at the 1064 nm wavelength was significantly greater than that at the other three wavelengths (p ≤ 0.0017). At a surface irradiance of ~157 mW/cm2, corresponding to 0.5 W light applied with the treatment head directly in contact with the skin, the intra-spinal irradiance at 1064 nm reached 0.137 ± 0.095 mW/cm2. Obtaining a dosage of PBMT-associative wavelengths of this magnitude at the level of the spinal canal may guide focused research into the transcutaneous applicability of PBMT for spinal cord injuries.

Photo-neuro-modulation (PNM), or photobiomodulation therapy (PBMT) of neuronal tissue, has demonstrated stimulating axonal growth of the spinal cord after acute structural damage in rodent models. The effectiveness of PNM for rodent models of spinal cord injury has been established at terminal irradiances of approximately 3.2mW/cm2. For clinical translation however, the existing surface irradiation protocol results in significant treatment dose attenuation by the vertebral bones as the light travels to the spinal cord. We reported that with a surface CW power and irradiance as intense as 10W and 3.14W/cm2 respectively less than 100µW/cm2 irradiance reached the spinal cord level of dogs. In exploring clinical transmission of photobiomodulatory irradiance to the spinal cord level, we piloted in a cadaveric rabbit model local light delivery to the cerebral-spinal-fluid (CSF) space using a 200µmx1.75mm (diameterxlength) diffuser fiber at L6/7 via a spinal needle. The irradiances at multiple sites of up to 9 centimeters distance along the spinal canal were measured sequentially by a second diffuser fiber via the corresponding vertebrae disks. At an intra-spinal irradiation of 8mW CW 830nm light which was 1/1,250 of the 10W surface power used for the transcutaneous dosimetry in dogs, irradiances at 1.5~2cm from the local delivery site were 1~2 mW/cm2 (2 rabbits, 4 measurements). The distance-dependent irradiances along the spinal canal corresponded to an effective attenuation coefficient of 0.1021±0.0213 mm-1 (n=4). In comparison (p=0.0274), the distance-dependent irradiances along the epaxial muscle upon interstitial delivery corresponded to an effective attenuation coefficient of 0.0677±0.0105 mm-1 (n=4). “Epidural” PNM is feasible.

This study assessed whether there was a scattering spectral marker quantifiable by reflectance measurements that could indicate early development of hepatic steatosis in rats for potential applications to pre-procurement organ evaluation. Sixteen rats were fed a methionine-choline-deficient (MCD) diet and eight rats were fed a normal diet. Direct assessment of the liver parenchyma of rats in vivo was performed by percutaneous reflectance spectroscopy using a single fiber probe at the beginning of diet-intake and arbitrary post-diet-intake times up to 11 weeks to render longitudinal comparison. Histological sampling of the liver over the duration of diet administration was performed on two MCD-diet treated rats and one control rat euthanized after reflectance spectroscopy measurement. The images of hematoxylin/eosin-stained liver specimens were analyzed morphometrically to evaluate the lipid size changes associated with the level of steatosis. The MCD-diet-treated group ([Formula: see text]) had mild steatosis in seven rats, moderate in three rats, severe in six rats, and no other significant pathology. No control rats ([Formula: see text]) developed hepatic steatosis. Among the parameters retrieved from per-SfS, only the scattering power (can be either positive or negative) appeared to be statistically different between MCD-treated and control livers. The scattering power for the 16 MCD-diet-treated livers at the time of euthanasia and presenting various levels of steatosis was [Formula: see text], in comparison to [Formula: see text] of the eight control livers [Formula: see text]. When evaluated at days 12 and 13 combined, the scattering power of the 16 MCD-diet-treated livers was [Formula: see text], in comparison to [Formula: see text] of the eight control livers ([Formula: see text]). All of four MCD-treated livers harvested at days 12 and 13 presented mild steatosis with sub-micron size lipid droplets, even though none of the MCD-treated livers were sonographically remarkable for fatty changes. The elevation of the scattering power may be a valuable marker indicating early hepatic steatosis before the steatosis is sonographically detectable.

Surgeons operating laparoscopically often have to rely upon subjective visual cues for complete oncological control and avoiding tumor violation or iatrogenic injury to critical tissues. A laparoscopic imaging tool to allow assessment of tumor margin or identification of anatomical structures buried under the layer of tissue being dissected is desirable to probe tissue contrast at a few millimeters depth, visualize over the lateral view for resection guidance, have a non-microscopic field-of-view (FOV) adequate for rapid survey of the resection site, and form the image in real-time. Probing light diffusely propagated through tissue provides sub-surface sensitivity, but the image formation generally involves intense computation that may be costly to intraoperative time-frame. Projecting these modalities laparoscopically to sample subsurface tissue heterogeneity over a non-microscopic FOV for rapid site-survey has been challenging. We demonstrate a laparoscopic applicator probe and a method thereof for real-time en-face mapping of near-surface heterogeneity for potential use towards intraoperative margin assessment. The probe fits a 12mm port and houses at 128 copper-coated 750μm fibers that form radially alternating illumination (70 fibers) and detection (58 fibers) channels. By simultaneously illuminating the 70 source channels of the laparoscopic probe that is in contact with a scattering medium and concurrently measuring the light diffusely propagated to the 58 detector channels, the presence of near-surface optical heterogeneities can be resolved in an en-face 9.5mm field-of-view in real-time. Visualization of subsurface margin of strong attenuation contrast at a depth up to 3mm is demonstrated at a frame rate of 1.25Hz.

Photobiomodulation (PBM) has been used successfully for the treatment of nervous system and has been demonstrated in the rodent model. In contrast, the percutaneous use of PBM to treat spinal cord of companion animals is expected to be challenging due to the significant attenuation of light energy as it travels through the thick and heterogeneous layers of tissue and bone to reach the level of the spinal cord. This pilot study was performed on a cadaverous dog to determine if the recommended bio-stimulatory treatment dose can be delivered to the spinal canal via percutaneous application of a clinically acceptable surface dose. The dose reaching the spinal canal after percutaneous application was measured at 980nm by using a miniature photo-diode sensor with a dose-response sensitivity of 1V per 1mW/cm2 dose and a 2mm spherical isotropic fiber-optical diffusor probe. The two sensors were embedded in different longitudinal positions along the dorsal portion of the spinal canal just below the soft tissues and vertebral processes in a 40lbs cadaverous dog. The spinal cord was then accessed via a hemilaminectomy. Once embedded in the target tissue, 1W-10 W surface irradiation was applied. At the T12/13 and T13/L1 intervertebral disc positions, photo-diode sensors detected the intra-spinal dose above the noise floor at the 10W surface dose. A narrow treatment window for percutaneous PBM in large dog may exist only for the shallowest segment of the spinal cord, which may be important to avoid potential collateral photothermal effects. Works for simultaneous multi-site intra-spinal measurements are on-going.

Laparoscopic diffuse optical spectroscopy (DOS) is demonstrated with fiber-probes attached to a bipolar-device. The DOS spectra acquired over a 10mm fiber-separation differentiated a 4mm vessel or ureter simulating-structure at a 2mm-depth in tissue.

Inadvertent injury to important anatomic structures is a significant risk in minimally invasive surgery (MIS) that potentially requires conversion to an open procedure, which results in increased morbidity and mortality. Surgeons operating minimal-invasively currently do not have an easy-to-use, real-time device to aid in intraoperative identification of important anatomic structures that underlie tissue planes. We demonstrate freehand diffuse optical spectroscopy (DOS) imaging for intraoperatively identifying major underlying veins and arteries. An applicator probe that can be affixed to and detached from an 8-mm laparoscopic instrument has been developed. The 10-mm DOS source-detector separation renders sampling of tissue heterogeneities a few millimeters deep. DOS spectra acquired consecutively during freehand movement of the applicator probe on the tissue surface are displayed as a temporal and spectral image to assist in spatially resolved identification of the underlying structures. Open surgery identifications of the vena cava and aorta underlying peritoneal fat of ∼4  mm in thickness using the applicator probe under room light were demonstrated repeatedly in multiple pigs in vivo.

When shell damage occurs in chelonians, fractures and/or areas of barrier disruption often lead to secondary infections and loss of shell integrity. Timely healing depends on fragment stabilization and proper wound care. Wound management is problematic in aquatic and semiaquatic chelonians, as they must remain in water for natural physiologic functions. The purpose of this investigation was to develop a waterproof wound shield allowing routine husbandry and encourage natural behaviors during healing of shell and skin wounds. A nontoxic, underwater epoxy (Aqua-Stix, Two Little Fishies, Inc., Miami Gardens, FL USA) was applied to shells of 14 red-eared sliders (Trachemys scripta elegans) around an approximately 1cm, surgically created, full-thickness shell wound. A urine specimen cup was cut in half, and the uppercut edge was seated into the center of the epoxy, leaving the cup lumen exposed over the wound. Special attention was paid to applying the ring of epoxy congruent with the shell scutal plates and embedding the epoxy tightly to the cup. The specimen lid was then threaded into place before the subjects were exposed to water. Infrared thermography determined thermal effects of epoxy application by using an ETIP 7320 P-Series infrared camera (Infrared Cameras Inc., Beaumont, TX USA). The average baseline shell temperature was 24°C. During epoxy application, local temperature increased from 28°C to 32°C, followed by rapid (<5 minutes) temperature reduction. Turtles showed no noticeable discomfort during application, and the wound shield remained water tight for 6 months allowing study subjects to recover under more physiologic conditions (aquatic environment).

OBJECTIVE To determine rate of recurrence of disk herniation in dogs that underwent percutaneous laser disk ablation (PLDA) because of a previous episode of suspected or confirmed thoracolumbar intervertebral disk herniation (IVDH). DESIGN Retrospective case series. ANIMALS 303 dogs that underwent PLDA and for which a minimum of 3 years of follow-up information was available (n = 294) or for which recurrence was documented within 3 years after the procedure (9). PROCEDURES Information on signalment, previous episodes of IVDH, specifics of the PLDA procedure, and recurrence was obtained from the medical records. Owners were contacted to complete a questionnaire regarding outcome and recurrence. RESULTS 60 of the 303 (19.8%) dogs had an episode of suspected or confirmed IVDH after undergoing PLDA, but only 11 of the 303 (3.6%) dogs had a recurrence of IVDH confirmed by means of CT or MRI and hemilaminectomy. Recurrence rate following PLDA was not significantly different between dogs that had been treated medically for previous episodes of IVDH and dogs that had been treated surgically. Overall, 270 of 286 (94.4%) owners reported that their dog was the same (109 [38.1%]) or improved (161 [56.3%]) immediately after PLDA, and 265 (92.7%) owners rated their satisfaction with the procedure as ≥ 9 on a scale from 1 (completely dissatisfied) to 10 (completely satisfied). CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that PLDA was a relatively safe, minimally invasive procedure associated with a low rate of recurrence of disk herniation when performed in dogs with a history of previous episodes of suspected or confirmed IVDH.

We demonstrate a laparoscopic applicator probe and a method thereof for real-time en-face topographic mapping of near-surface heterogeneity for potential use in intraoperative margin assessment during minimally invasive oncological procedures. The probe fits in a 12mm port and houses at its maximum 128 copper-coated 750um fibers that form radially alternating illumination (70 fibers) and detection (58 fibers) channels. By simultaneously illuminating the 70 source channels of the probe that is in contact with a scattering medium and concurrently measuring the light diffusely propagated to the 58 detector channels, the presence of near-surface optical heterogeneities can be resolved in an en-face 9.5mm field-of-view in real-time. Visualization of a subsurface margin of strong attenuation contrast at a depth up to 3mm is demonstrated at one wavelength at a frame rate of 1.25Hz.

This study explores percutaneous single-fiber spectroscopy (SfS) of rat livers undergoing fatty infiltration. Eight test rats were fed a methionine-choline-deficient (MCD) diet, and four control rats were fed a normal diet. Two test rats and one control rat were euthanized on days 12, 28, 49, and 77 following initiation of the diet, after percutaneous SfS of the liver under transabdominal ultrasound guidance. Histology of each set of the two euthanized test rats showed mild and mild hepatic lipid accumulations on day 12, moderate and severe on day 28, severe and mild on day 49, and moderate and mild on day 77. Livers with moderate or higher lipid accumulation generally presented higher spectral reflectance intensity when compared to lean livers. Livers of the eight test rats on day 12, two of which had mild lipid accumulation, revealed an average scattering power of 0.37 +/- 0.14 in comparison to 0.07 +/- 0.14 for the four control rats (p < 0.01). When livers of the test rats with various levels of fatty infiltration were combined, the average scattering power was 0.36 +/- 0.15 in comparison to 0.14 +/- 0.24 of the control rats (0.05 < p < 0.1). Increasing lipid accumulation in concentration and size seemed to cause an increase of the scattering power prior to increasing total spectral reflectance. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

Percutaneous single-fiber spectroscopy was applied in vivo to livers of rats fed a control diet (8 rats) and a methionine-choline-deficient diet (16 rats). Lipid accumulation was associated with changes in spectroscopy-extracted scattering parameters.

The objectives of this study were to: 1) determine if mild hyperthermia (40–42°C) can sensitize tumor cells for more effective proton beam radiotherapy (PBRT); 2) characterize the survival fraction of cells exposed to PBRT; and 3) characterize release of the drug doxorubicin (Dox) from low temperature sensitive liposomes (LTSLs) without exposure to mild hyperthermia in combination with PBRT.

Background and objectivesIntervertebral disc herniation is a common disease in chondrodystrophic dogs, and a similar neurologic condition also occurs in humans. Percutaneous laser disc ablation (PLDA) is a minimally invasive procedure used increasingly for prevention of disc herniation. Currently, PLDA is performed on thoracolumbar discs with the same laser energy applied regardless of the differing extent of degeneration among mineralized discs. In a previous study performed on 15 normal and 6 degenerated intervertebral discs in chondrodystrophoid canine species, it was demonstrated that percutaneous single‐fiber reflectance spectroscopy (SfRS) detected increased light scattering from mineralized intervertebral discs when comparing to normal discs. The objective of this study is to evaluate how SfRS evaluation of mineralized discsin situfairs with X‐ray radiography and computed tomography (CT) diagnoses and if SfRS sensing of the scattering changes correlates with the level of mineral degeneration in nucleus pulposus.Materials and MethodsPercutaneous SfRS was performed on a total of 28 intervertebral discs of three dogs post‐mortem, through a 20 gauge spinal needle standard to PLDA. The raw SfRS measurement was normalized to extract a dimension‐less spectral intensity profile, from which the average over 600–900 nm was used as the SfRS intensity index to compare among the measured discs. The discs were imaged prior to percutaneous SfRS by radiography and CT, and harvested after percutaneous SfRS for histopathologic examinations.ResultsFive among 10 discs of dog #1, six among 9 discs of dog #2, and nine out of 9 discs of dog #3 were determined by histopathology to have central focal or multi‐focal areas of mineralization occupying 5–75% of the examined area of nucleus pulposus. The overall numbers of discs with detectable and undetectable central mineralization were 20 and 8, respectively. CT resulted in one false positive (FP) and four false negative (FN) diagnoses for dog #1, three FP and zero FN diagnoses for dog #2, and zero FP and one FN diagnosis for dog #3. Of the total 28 discs the CT had an overall positive predictive value (PPV) of 78.8% and an overall negative predictive value (NPV) of 44.4%. X‐ray radiography gave five FN diagnoses for dog #1, two FN diagnoses for dog #2, and eight FN diagnoses for dog #3. Of the total 28 discs the radiography had an overall PPV of 100% and an overall NPV of 30.4%. The receiver‐operating‐characteristic analysis of the SfRS measurement was performed on 24 discs that had a central mineralization not greater than 50%. An area‐under‐curve of 0.6758 infers that the SfRS intensity weakly indicates the level of mineralization.ConclusionsPercutaneous SfRS may be useful as anin situsensing tool for assessing the level of mineral degeneration in intervertebral discs for the prospect of disc‐specific dosage adjustment in PLDA. Lasers Surg. Med. 46:508–519, 2014. © 2014 Wiley Periodicals, Inc.

We demonstrate the feasibility of diffuse optical tomography (DOT) of the proximal pancreas by using optical applicator channels deployed longitudinally along the exterior surface of a duodenoscope. As the duodenum that nearly encircles the proximal pancreas forms a natural "C-loop" that is approximately three-quarters of a circle of 5-6 cm in diameter, a multichannel optical applicator attached to a duodenoscope has the potential to perform transduodenal DOT sampling of the bulk proximal pancreas wherein most cancers and many cystic lesions occur. The feasibility of transduodenal DOT is demonstrated on normal porcine pancreas tissues containing an introduced gelatinous inclusion of approximately 3 cm in diameter, by using nine source channels and six detector channels attached to a duodenoscope. Concurrent ultrasonography of the gelatinous inclusion in the porcine pancreas parenchyma provided a coarse, albeit indispensable, anatomic prior to transduodenal DOT in reconstructing a contrast of optical properties in the pancreas.