Preliminary investigations on therapy thresholds for laser dosimetry, cryogen spray cooling duration, and treatment cycles for laser cartilage reshaping in the New Zealand white rabbit auricle.

Previous studies have demonstrated the feasibility of laser irradiation (λ = 1.45 μm) in tandem with cryogen spray cooling (CSC) to reshape rabbit auricular cartilage using a total energy density of 14 J/cm(2). The aim of this study was to further explore and identify the dosimetry parameter space for laser output energy, CSC duration, and treatment cycles required to achieve shape change while limiting skin and cartilage injury. Ten New Zealand white rabbits were treated with the 1.45 μm diode laser combined with cryogen spray cooling (Candela Smoothbeam™, Candela Co., Wayland, MA, USA). The ear's central portion was bent around a cylindrical jig and irradiated in consecutive spots of 6 mm diameter (13 or 14 J/cm(2) per spot) along three rows encompassing the bend. CSC was delivered during irradiation in cycles consisting of 25-35 ms. At thin and thick portions of the ear, 4-7 and 6-10 treatment cycles were delivered, respectively. After surgery, ears were examined and splinted for 6 weeks. Treatment parameters resulting in acceptable (grades 1 and 2) and unacceptable (grade 3) skin injuries for thick and thin regions were identified, and shape change was observed. Confocal and histological analysis of cartilage tissue revealed several outcomes correlating to laser dosimetry, CSC duration, and treatment cycles. These outcomes included expansion of cartilage layers (thickening), partial cartilage injuries, and full-thickness cartilage injuries. We determined therapy thresholds for laser output energy, cryogen spray cooling duration, and treatment cycles in the rabbit auricular model. These parameters are a starting point for future clinical procedures aimed at correcting external ear deformities

Preliminary investigations on therapy thresholds for laser dosimetry, cryogen spray cooling duration, and treatment cycles for laser cartilage reshaping in the New Zealand white rabbit auricle.

Previous studies have demonstrated the feasibility of laser irradiation (λ = 1.45 μm) in tandem with cryogen spray cooling (CSC) to reshape rabbit auricular cartilage using a total energy density of 14 J/cm(2). The aim of this study was to further explore and identify the dosimetry parameter space for laser output energy, CSC duration, and treatment cycles required to achieve shape change while limiting skin and cartilage injury. Ten New Zealand white rabbits were treated with the 1.45 μm diode laser combined with cryogen spray cooling (Candela Smoothbeam™, Candela Co., Wayland, MA, USA). The ear's central portion was bent around a cylindrical jig and irradiated in consecutive spots of 6 mm diameter (13 or 14 J/cm(2) per spot) along three rows encompassing the bend. CSC was delivered during irradiation in cycles consisting of 25-35 ms. At thin and thick portions of the ear, 4-7 and 6-10 treatment cycles were delivered, respectively. After surgery, ears were examined and splinted for 6 weeks. Treatment parameters resulting in acceptable (grades 1 and 2) and unacceptable (grade 3) skin injuries for thick and thin regions were identified, and shape change was observed. Confocal and histological analysis of cartilage tissue revealed several outcomes correlating to laser dosimetry, CSC duration, and treatment cycles. These outcomes included expansion of cartilage layers (thickening), partial cartilage injuries, and full-thickness cartilage injuries. We determined therapy thresholds for laser output energy, cryogen spray cooling duration, and treatment cycles in the rabbit auricular model. These parameters are a starting point for future clinical procedures aimed at correcting external ear deformities

Preliminary investigation on use of high-resolution optical coherence tomography to monitor injury and repair in the rat sciatic nerve.

Background and objectiveOptical coherence tomography (OCT) has been used in limited settings to study peripheral nerve injury. The purpose of the study is to determine whether high-resolution OCT can be used to monitor nerve injury and regeneration in the rat sciatic nerve following crush injury, ligation, and transection with microsurgical repair.Study design/materials and methodsForty-five rats were segregated into three groups. The right sciatic nerve was suture ligated (n = 15), cut then microsurgically repaired (n = 15), or crushed (n = 15). The left sciatic nerve served as the control; only surgical exposure and skin closure were performed. Each group was further divided into three subgroups where they were assigned survival durations of 4, 15, or 24 weeks. Following euthanasia, nerves were harvested, fixed in formalin, and imaged at the injury site, as well as proximal and distal ends. The OCT system resolution was approximately 7 microm in tissue with a 1,060 nm central wavelength.ResultsControl (uninjured) nerve tissue showed homogenous signal distribution to a relatively uniform depth; in contrast, damaged nerves showed irregular signal distribution and intensity. Changes in signal distribution were most significant at the injury site and distal regions. Increases in signal irregularity were evident during longer recovery times. Histological analysis determined that OCT imaging was limited to the surrounding perineurium and scar tissue.ConclusionOCT has the potential to be a valuable tool for monitoring nerve injury and repair, and the changes that accompany wound healing, providing clinicians with a non-invasive tool to treat nerve injuries

Preliminary investigation on use of high-resolution optical coherence tomography to monitor injury and repair in the rat sciatic nerve.

Background and objectiveOptical coherence tomography (OCT) has been used in limited settings to study peripheral nerve injury. The purpose of the study is to determine whether high-resolution OCT can be used to monitor nerve injury and regeneration in the rat sciatic nerve following crush injury, ligation, and transection with microsurgical repair.Study design/materials and methodsForty-five rats were segregated into three groups. The right sciatic nerve was suture ligated (n = 15), cut then microsurgically repaired (n = 15), or crushed (n = 15). The left sciatic nerve served as the control; only surgical exposure and skin closure were performed. Each group was further divided into three subgroups where they were assigned survival durations of 4, 15, or 24 weeks. Following euthanasia, nerves were harvested, fixed in formalin, and imaged at the injury site, as well as proximal and distal ends. The OCT system resolution was approximately 7 microm in tissue with a 1,060 nm central wavelength.ResultsControl (uninjured) nerve tissue showed homogenous signal distribution to a relatively uniform depth; in contrast, damaged nerves showed irregular signal distribution and intensity. Changes in signal distribution were most significant at the injury site and distal regions. Increases in signal irregularity were evident during longer recovery times. Histological analysis determined that OCT imaging was limited to the surrounding perineurium and scar tissue.ConclusionOCT has the potential to be a valuable tool for monitoring nerve injury and repair, and the changes that accompany wound healing, providing clinicians with a non-invasive tool to treat nerve injuries