What is the role of spectroscopy in surgery?

Role of Spectroscopy in Surgery

Spectroscopy serves as a powerful real-time diagnostic tool in surgery that enables intraoperative tissue characterization, tumor margin assessment, and virtual histology without requiring traditional biopsies, significantly improving surgical precision and patient outcomes. 1

Types of Spectroscopic Techniques Used in Surgery

Optical Biopsy Techniques

• Optical biopsy methods allow cellular, subcellular, and even atomic-level information to be obtained during surgery without requiring traditional tissue removal 1
• These techniques provide real-time tissue characterization that can guide surgical decision-making and improve precision 1

Light-Scattering Spectroscopy

• Recent refinements enable resolution of structures measured in nanometers, providing 20-50 times greater detail than conventional light microscopy 1
• Can probe tissues to greater depth than conventional microscopy, allowing detection of histologic evidence of preneoplastic changes 1

Raman Spectroscopy

• Yields more detailed molecular information than fluorescence by detecting specific molecular vibrations that indicate detailed atomic information 1
• In vivo experiments have demonstrated that Raman spectra can distinguish between normal tissue and dysplastic tissue, such as Barrett's specialized intestinal metaplasia versus high-grade dysplasia 1

Diffuse Reflectance Spectroscopy (DRS)

• Enables real-time tissue characterization during surgery by analyzing how light is reflected from tissues 2
• Has shown high accuracy (93%) in distinguishing malignant from healthy breast tissue during surgical procedures 2
• Can function even through coagulated tissue layers created by electrosurgical knives, maintaining its discriminatory capabilities 3

Optical Emission Spectroscopy (OES)

• Analyzes ionized atoms and molecules generated during electrosurgical treatment to differentiate tissue types 4
• Recent studies show 96.9% accuracy in distinguishing normal from abnormal breast tissue with high sensitivity (94.8%) and specificity (99.0%) 4

Clinical Applications in Surgery

Tumor Margin Assessment

• Fluorescence-guided surgery (FGS) enables real-time identification of tumor margins, helping surgeons achieve complete resection 1
• Spectroscopy can be used at three critical surgical timepoints: before excision to locate the primary tumor, during exposure of the tumor with surrounding normal tissue visible, and after resection to assess the wound bed 1
• One of the biggest gaps in oncologic surgery is the high rate of positive margins, which directly correlates with poor survival and locoregional recurrence 1

Intraoperative Tumor Identification

• Spectroscopy can identify subclinical disease or occult tumor deposits that would otherwise be missed during conventional visual inspection 1
• Particularly valuable in extensive debulking procedures for ovarian cancer, brain cancer, or peritoneal metastases where complete resection leads to prolonged survival 1

Specimen Mapping and Pathology Correlation

• Fluorescent "hot spots" can direct clinicians toward suspicious regions on resected specimens, reducing sampling error during pathological examination 1
• This approach can reduce the time needed for specimen analysis by targeting sampling to fluorescence-positive areas rather than examining all surfaces of large tumor specimens 1

Lymph Node Assessment

• Spectroscopy combined with SPECT/CT imaging can identify sentinel lymph nodes with greater precision than conventional techniques 1
• This helps in detecting tumor-positive lymph nodes that might indicate metastatic disease, potentially altering surgical decision-making 1

Specific Applications by Surgical Specialty

Gastrointestinal Surgery

• Endocytoscopy combined with spectroscopy allows in vivo visualization of cellular details during GI procedures 1
• Confocal microscopy with spectroscopy has shown 97.4% sensitivity and 99.4% specificity for detection of neoplastic changes during screening colonoscopy 1

Neurosurgery

• MR Spectroscopy helps differentiate tumor from radiation necrosis in brain tissue and can assist in identifying optimal biopsy targets 1
• Provides metabolic information about brain tumors that complements structural imaging 1

Breast Surgery

• DRS has demonstrated high accuracy in distinguishing malignant from healthy breast tissue during surgery 2
• OES has shown potential for real-time margin assessment during breast cancer surgery with 96.9% accuracy 4

Urologic Surgery

• Spectroscopy can differentiate between benign parenchyma and malignant tissue in urothelial carcinoma, renal cell carcinoma, and prostate adenocarcinoma 5
• Has potential to detect biologically aggressive high-risk disease and classify natural biomarkers in urologic malignancies 5

Implementation Challenges and Considerations

Standardization Requirements

• Strict standardization of imaging protocols, data collection, and analysis is necessary to obtain quantitative, accurate, and reproducible results 1
• Similar to PET imaging standardization, spectroscopy requires consistent injection techniques, imaging times, and analysis methods 1

Technical Limitations

• Proximity to vessels, air spaces, or bone can interfere with some spectroscopic techniques 1
• Small volume lesions or tumors in specific locations (e.g., spinal cord) may be challenging to assess 1

Integration into Surgical Workflow

• Incorporation of spectroscopic techniques must be individualized to the specific procedure being performed and cancer type being resected 1
• During minimally-invasive and robotic surgery, real-time detection of fluorescence can be easily integrated as surgeons already operate using screens to visualize the surgical field 1

Future Directions

• Development of quantitative fluorescence spectroscopy methods that can determine fluorophore concentration in tissues during surgery 1
• Machine learning approaches to automate quantification and classification of spectroscopic data 1
• Integration of multiple spectroscopic techniques into standard surgical instruments to provide real-time feedback during tissue cutting and coagulation 3