A handheld and biocompatible mass spectrometry system provides nondestructive molecular diagnosis of cancer tissue samples.

Minimally invasive neurological surgeries are increasingly being sought after for treatment in neurological pathologies and oncology. A critical limitation in these minimally invasive procedures is lack of specialized tools that allow for space-time controlled delivery of sufficient energy for coagulation and cutting of tissue. Advent of fiber-lasers provide high average power with improved beam quality (lower M²), biocompatible silica fiber delivery, reduced cost of manufacturing, and radiant output stability over long operating periods. Despite these advancements, no fiber-laser based surgical tools are currently available for tissue resection in vivo. Here we demonstrate a first to our knowledge, fiber-laser platform for performing precise brain surgery in a murine brain model. In this study, our primary aims were to first demonstrate efficacy of fiber-lasers in performing precise blood-less surgery in a murine brain with limited non-specific thermal damage. Second, fiber-lasers’ ability to deliver radiant energy through biocompatible silica fibers was explored in a murine brain model for blood less resection. A bench-top optical coherence tomography (OCT) guided fiber-laser platform was constructed with a stereotactic stage for performing precision brain surgery. A pulsed quasi-continuous wave ytterbium (Yb) fiber-laser (1.07 µm) was used to perform vascular specific coagulation while a pulsed nanosecond thulium fiber-laser (1.94 µm) was used to conduct bloodless cutting, all under the guidance of a swept-source OCT system centered at 1310 +/- 70 nm. Specialty linear and circular cuts were made in an in vivo murine brain for bloodless brain tissue resection. The two fiber-lasers were combined into a single biocompatible silica fiber to conduct brain surgery resection under the bench-top OCT system’s imaging microscope. Vascular specific coagulation was demonstrated in all five mice studied. Bloodless linear cuts and point cuts were demonstrated in vivo. Histologically, thermal injury was measured to be less than 100 µm while a removal rate of close to 5 mm³/s was achieved with an average Tm fiber-laser power of 15 W. To the authors’ knowledge, this is the first demonstration of a fiber-laser platform for conducting in vivo bloodless brain tissue resection with a pulsed thulium (Tm) fiber-laser and a quasi-continuous wave (QCW) Yb fiber-laser. The demonstrated fiber-laser platform, if successfully configured for use in the operating room (OR), can provide surgeons a tool for rapid removal of tissue while making surgical resections of brain regions more precise, and can be basis for a flexible cutting tool capable of reaching hard-to-operate regions.

Photocoagulation of blood vessels offers unambiguous advantages to current radiofrequency approaches considering the high specificity of blood absorption at available laser wavelengths (e.g., 532 nm and 1.064 µm). Successful treatment of pediatric vascular lesions, such as port-wine stains requiring microvascular hemostasis, has been documented. Although laser treatments have been successful in smaller diameter blood vessels, photocoagulation of larger sized vessels is less effective. The hypothesis for this study is that a primary limitation in laser coagulation of large diameter blood vessels (500–1000 µm) originates from shear stress gradients associated with higher flow velocities along with temperature-dependent viscosity changes. Laser (1.07 µm) coagulation of blood vessels was tested in the chicken chorio-allantoic membrane (CAM). A finite element model is developed that includes hypothetical limitations in laser coagulation during irradiation. A protocol to specify laser dosimetry is derived from OCT imaging and angiography observations as well as finite element model results. Laser dosimetry is applied in the CAM model to test the experimental hypothesis that blood shear stress and flow velocity are important parameters for laser coagulation and hemostasis of large diameter blood vessels (500–1000 µm). Our experimental results suggest that shear stress and flow velocity are fundamental in the coagulation of large diameter blood vessels (500–1000 µm). Laser dosimetry is proposed and demonstrated for successful coagulation and hemostasis of large diameter CAM blood vessels.