01
Intravascular Imaging OCT Spectroscopy 2025
Quantitative Spectroscopic OCT for Coronary Plaque Characterization
Northeastern Symposium of Biomedical Optics (NESBO) · MIT · Gallegos et al.
The Problem

Coronary artery disease is the world's leading cause of death. Current intravascular OCT shows where plaques are — but not what they're made of. Plaque composition (lipid-rich necrotic core, fibrous cap, calcification) is the primary determinant of rupture risk, yet this information is invisible to standard OCT.

Spectroscopic OCT can extract compositional data from wavelength-dependent tissue attenuation, but coherent speckle noise corrupts spectral estimates — a barrier blocking clinical translation for over a decade.

What I Built
Developed a quantitative spectroscopic OCT framework that mitigates coherent noise artifacts in spectral estimation
Validated compositional discrimination in controlled tissue-mimicking phantoms with known optical properties
Demonstrated wavelength-dependent attenuation mapping as a pathway toward in-vivo coronary plaque typing
Why It Matters

Real-time, label-free, compositionally-specific intravascular imaging could transform interventional cardiology — enabling risk stratification before rupture rather than responding after an acute MI. This work is a direct building block toward spectroscopic OCT as standard-of-care. The computational techniques are also broadly applicable to any coherent imaging system requiring quantitative spectroscopic characterization.

02
Photoacoustic Imaging NIR-II Fiber Lasers 2025
Multi-Spectral NIR-II Photoacoustic Microscopy via Custom Fiber Amplifier
Celebration of Science (COS) · Massachusetts General Hospital · Gallegos et al.
The Problem

Label-free discrimination of lipids and collagen — key disease markers in cardiovascular and connective tissue pathology — requires spectroscopic imaging in the NIR-II window (1000–1700 nm). No compact, fiber-based, multi-wavelength system existed for this regime, creating a fundamental hardware bottleneck.

What I Built
Co-developed a custom all-fiber amplifier system for multi-spectral NIR-II excitation at previously inaccessible wavelengths
Built quantitative spectroscopic unmixing algorithms for robust lipid and collagen discrimination
Validated label-free molecular contrast in ex-vivo tissue without exogenous labels or contrast agents
Why It Matters

This platform enables label-free molecular imaging in a spectral window previously inaccessible to compact systems. The combination of custom hardware and quantitative algorithms opens pathways to clinical diagnostics, industrial materials inspection, and any application requiring chemically-specific optical characterization without contrast agents. The all-fiber architecture is a critical step toward translation from bench to clinic and industry.

Technical Context

Coherent Imaging & Interferometry

Optical coherence tomography uses broadband light interferometry for high-resolution cross-sections at micron scale. Spectroscopic extensions exploit frequency-domain content to extract wavelength-dependent material properties — yielding chemical contrast, not just structure.

Photoacoustic Sensing

Combines the molecular specificity of optical spectroscopy with the penetration depth of ultrasound. Pulsed laser excitation generates acoustic waves from target chromophores. Multi-spectral acquisition enables unmixing of molecular species without exogenous labels.

The NIR-II Window

The second near-infrared window (1000–1700 nm) offers reduced scattering and absorption relative to visible wavelengths, enabling deeper penetration into materials and tissue. Distinct spectroscopic signatures in this regime make it ideal for label-free molecular discrimination.

The Coherent Noise Problem

Coherent imaging modalities suffer from speckle noise — a multiplicative interference artifact that corrupts spectral content. Mitigating speckle while preserving spectroscopic fidelity has been a fundamental barrier to quantitative spectroscopic imaging for over a decade.

Future Directions

These projects are building blocks — the techniques generalize well beyond their original domains.

01
In-Vivo & Real-World Translation

Extending spectroscopic and photoacoustic methods from controlled environments to real-world conditions — addressing motion artifacts, depth requirements, and real-time computation.

02
Multi-Modal & Computational Fusion

Combining structural imaging with molecular contrast and computational methods to produce co-registered, multi-parametric maps — structural and chemical information in a single acquisition.

03
Materials & Industrial Sensing

Translating spectroscopic imaging algorithms to industrial materials characterization, energy systems, and advanced manufacturing — label-free, non-destructive chemical sensing at scale.