An official website of the United States government
Tissue development requires local and long-distance communication between cells. Cell ablation experiments have provided critical insights into the functions of specific cell types and the tissue surrounding the dead cells. In theDrosophilaneuromuscular system, ablation of motor neurons and muscles has revealed the roles of the ablated cells in axon pathfinding and circuit wiring. For example, when muscles are denervated due to laser ablation of their motor neuron inputs, they receive ectopic innervation from neighboring motor neurons. Here, we describe two methods of specific cell ablation. The first is a genetic ablation approach that usesGAL4(ideally expressed in a small subset of cells) to drive expression of cell death genesreaperandhead involution defective. The second method relies on reactive oxygen species produced by light activation of theArabidopsis-derived Singlet Oxygen Generator, miniSOG2, expressed in a subset of cells. For the latter, the precision stems from both theGAL4and the restricting of the blue-light stimulation area.
more »
« less
Photoacoustic image guidance for laser tonsil ablation: approach and initial results
Tonsillectomy, one of the most common surgical procedures worldwide, is often associated with postoperative complications, particularly bleeding. Tonsil laser ablation has been proposed as a safer alternative; however, its adoption has been limited because it can be difficult for a surgeon to visually control the thermal interactions that occur between the laser and the tissue. In this study, we propose to monitor the ablation caused by a CO2 laser on ex-vivo tonsil tissue using photoacoustic imaging. Soft tissue’s unique photoacoustic spectra were used to distinguish between ablated and non-ablated tissue. Our results suggest that photoacoustic imaging is able to visualize necrosis formation and calculate the necrotic extent, offering the potential for improved tonsil laser ablation outcomes.
more »
« less
- Award ID(s):
- 2237011
- PAR ID:
- 10520321
- Editor(s):
- Rettmann, Maryam E; Siewerdsen, Jeffrey H
- Publisher / Repository:
- SPIE
- Date Published:
- ISBN:
- 9781510671607
- Page Range / eLocation ID:
- 44
- Format(s):
- Medium: X
- Location:
- San Diego, United States
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Photoacoustic imaging is a promising technique to provide guidance during multiple surgeries and procedures. One challenge with this technique is that major blood vessels in the liver are difficult to differentiate from surrounding tissue within current safety limits, which only exist for human skin and eyes. In this paper, we investigate the safety of raising this limit for liver tissue excited with a 750 nm laser wavelength and approximately 30 mJ laser energy (corresponding to approximately 150 mJ/cm2fluence). Laparotomies were performed on six swine to empirically investigate potential laser-related liver damage. Laser energy was applied for temporal durations of 1 minute, 10 minutes, and 20 minutes. Lasered liver lobes were excised either immediately after laser application (3 swine) or six weeks after surgery (3 swine). Cell damage was assessed using liver damage blood biomarkers and histopathology analyses of 41 tissue samples total. The biomarkers were generally normal over a 6 week post-surgicalin vivostudy period. Histopathology revealed no cell death, although additional pathology was present (i.e., hemorrhage, inflammation, fibrosis) due to handling, sample resection, and fibrous adhesions as a result of the laparotomy. These results support a new protocol for studying laser-related liver damage, indicating the potential to raise the safety limit for liver photoacoustic imaging to approximately 150 mJ/cm2with a laser wavelength of 750 nm and for imaging durations up to 10 minutes without causing cell death. This investigation and protocol may be applied to other tissues and extended to additional wavelengths and energies, which is overall promising for introducing new tissue-specific laser safety limits for photoacoustic-guided surgery.more » « less
-
Photoacoustic imaging–the combination of optics and acoustics to visualize differences in optical absorption – has recently demonstrated strong viability as a promising method to provide critical guidance of multiple surgeries and procedures. Benefits include its potential to assist with tumor resection, identify hemorrhaged and ablated tissue, visualize metal implants (e.g., needle tips, tool tips, brachytherapy seeds), track catheter tips, and avoid accidental injury to critical subsurface anatomy (e.g., major vessels and nerves hidden by tissue during surgery). These benefits are significant because they reduce surgical error, associated surgery-related complications (e.g., cancer recurrence, paralysis, excessive bleeding), and accidental patient death in the operating room. This invited review covers multiple aspects of the use of photoacoustic imaging to guide both surgical and related non-surgical interventions. Applicable organ systems span structures within the head to contents of the toes, with an eye toward surgical and interventional translation for the benefit of patients and for use in operating rooms and interventional suites worldwide. We additionally include a critical discussion of complete systems and tools needed to maximize the success of surgical and interventional applications of photoacoustic-based technology, spanning light delivery, acoustic detection, and robotic methods. Multiple enabling hardware and software integration components are also discussed, concluding with a summary and future outlook based on the current state of technological developments, recent achievements, and possible new directions.more » « less
-
Intraoperative imaging of slide-free specimens is crucial for oncology surgeries, allowing surgeons to quickly identify tumor margins for precise surgical guidance. While high-resolution ultraviolet photoacoustic microscopy has been demonstrated for slide-free histology, the imaging speed is insufficient, due to the low laser repetition rate and the limited depth of field. To address these challenges, we present parallel ultraviolet photoacoustic microscopy (PUV-PAM) with simultaneous scanning of eight optical foci to acquire histology-like images of slide-free fresh specimens, improving the ultraviolet PAM imaging speed limited by low laser repetition rates. The PUV-PAM has achieved an imaging speed of 0.4 square millimeters per second (i.e., 4.2 minutes per square centimeter) at 1.3-micrometer resolution using a 50-kilohertz laser. In addition, we demonstrated the PUV-PAM with eight needle-shaped beams for an extended depth of field, allowing fast imaging of slide-free tissues with irregular surfaces. We believe that the PUV-PAM approach will enable rapid intraoperative photoacoustic histology and provide prospects for ultrafast optical-resolution PAM.more » « less
-
Photoacoustic pulses generated by pulsed laser irradiation have the characteristics of high frequency and wide bandwidth, which are desirable for imaging and sensing. Efficient photoacoustic composites have been developed for fabricating photoacoustic transmitters capable of generating highamplitude ultrasound. Here, recent advances in photoacoustic transmitters are reviewed from an application perspective, starting with the fundamental aspects of photoacoustic generation. The topics discussed include various composite materials for photoacoustic generation, and their applications such as high-amplitude therapy, imaging and sensing, and photoacoustic waveform control.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1117/12.3007295
