Optical Imaging Techniques for Brain Tumor Diagnosis

Optical imaging techniques provide real-time, non-invasive methods for identifying and delineating brain tumours during diagnosis and surgical resection. Endogenous contrast mechanisms, notably the autofluorescence of metabolic coenzymes such as NADH and FAD and exogenous fluorophores like protoporphyrin IX, enable high-resolution mapping of tissue architecture. Methods such as fluorescence lifetime imaging microscopy (FLIM), two-photon fluorescence imaging, second harmonic generation (SHG) and multispectral spectroscopy allow discrimination of tumour tissue based on spectral signatures, fluorescence lifetimes and harmonic responses. Optical coherence tomography and Raman spectroscopy offer structural and molecular insights without requiring labels, while multimodal fibre-optic endomicroscopes integrate several modalities for intraoperative guidance. Recent advances in machine learning facilitate real-time analysis of thermal infrared signatures and spectral data, enhancing tumour boundary detection. Collectively, these developments promise improved diagnostic accuracy, more complete surgical resection and reduced recurrence rates by precisely differentiating infiltrative tumour margins from normal brain tissue.

Research from Nature Portfolio

Recent studies have demonstrated that multimodal optical measurement of fresh human brain samples can effectively distinguish various tumour types from healthy controls. In one approach, a fibre-based endoscope combined spectral analysis, two-photon fluorescence imaging and SHG to differentiate gliomas, metastases and meningiomas in real time, revealing distinct lifetime and spectral markers for tumour margins. Another investigation employed deep-ultraviolet to near-infrared excitation to derive optical signatures across excitation wavelengths; ratios such as tryptophan–collagen and optical redox indices enabled discrimination between healthy tissue and low- or high-grade gliomas. A further study tracked molecular changes across multiple scales using fluorescence microscopy, demonstrating that collagen crosslinks and endogenous coenzyme lifetimes correlate with meningioma grade and can guide precise surgical excision without exogenous dyes.

Optical Imaging Techniques for Brain Tumor Diagnosis publication trend

The graph below shows the total number of articles in optical imaging techniques for brain tumor diagnosis across all publications each year (not limited to Nature Index journals).

Technical terms

Autofluorescence: Emission of light by endogenous molecules upon excitation, used to distinguish tissue types.

Fluorescence lifetime imaging microscopy (FLIM): Technique measuring the decay time of fluorescence to characterise molecular environments.

Two-photon fluorescence imaging: Nonlinear microscopy using simultaneous absorption of two photons for deep tissue imaging with reduced photodamage.

Second harmonic generation (SHG): Nonlinear optical process where two photons combine to emit one photon at half the wavelength, sensitive to non-centrosymmetric structures like collagen.

Optical redox ratio: Metric derived from relative fluorescence intensities of NADH and FAD, indicating cellular metabolic state.

References

1. Review of the potential of optical technologies for cancer diagnosis in neurosurgery: a step toward intraoperative neurophotonics. Neurophotonics (2016).
2. Multimodal optical analysis discriminates freshly extracted human sample of gliomas, metastases and meningiomas from their appropriate controls. Scientific Reports (2017).
3. Optical Signatures Derived From Deep UV to NIR Excitation Discriminates Healthy Samples From Low and High Grades Glioma. Scientific Reports (2019).
4. Molecular changes tracking through multiscale fluorescence microscopy differentiate Meningioma grades and non-tumoral brain tissues. Scientific Reports (2021).
5. Label-Free Macroscopic Fluorescence Lifetime Imaging of Brain Tumors. Frontiers in Oncology (2021).
6. First in patient assessment of brain tumor infiltrative margins using simultaneous time-resolved measurements of 5-ALA-induced PpIX fluorescence and tissue autofluorescence. Journal of Biomedical Optics (2022).
7. Intraoperative thermal infrared imaging in neurosurgery: machine learning approaches for advanced segmentation of tumors. Physical and Engineering Sciences in Medicine (2023).