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Table 1 Summary of each endoscopic diagnostic technology

From: Novel endoscopic optical diagnostic technologies in medical trial research: recent advancements and future prospects

Technique

Excitation spectra

Frame rate (Hz)

Achievable

spatial resolution (μm)

Penetration depth (mm)

Functional information

Real morphologic image

Whether the probe is in direct contact with the tissue surface while operating

HSI

Visible & Near-IR

 > 30

 < 250

1

✔

✔

–

FLIM

UV-Blue

20–120

 < 50

 < 0.1

✔

✔

Non-contact

PAE

Visible & Near-IR

2–5

10

 > 1

✔

✔

Contact

OCT

Near-IR

 < 50

 < 3

2–4

✘

✔

Non-contact

CARS

Near-IR

0.01–0.2

 < 3

 > 1

✔

✔

Non-contact

TPEF/

SHG

Near-IR

1–8

 < 1

0.2–0.3

✔

✔

Contact or non-contact

3PEF/

THG

Near-IR

0.05–0.1

1

0.2–0.7

✔

✔

Contact or non-contact

DRS

Visible

0.02–2

–

 < 1

✘

✘

Contact

LSS

Visible

0.02–0.05

–

 < 1

✘

✘

Non-contact

a/LCI

Near-IR

1–4

–

 < 0.5

✘

✘

Contact

RS

Near-IR

0.1–10

–

 > 1

✔

✘

Contact

  1. HSI: hyperspectral imaging; FLIM: fluorescence lifetime imaging microscopy; PAE: photoacoustic endoscopy; OCT: optical coherent tomography; CARS: coherent anti-Stokes Raman scattering; TPEF: two-photon excited fluorescence; 3PEF: three-photon excited fluorescence; SHG: second-harmonic generations; THG: third-harmonic generations; DRS: diffuse reflectance spectroscopy; LSS: light-scattering spectroscopy; a/LCI: angle-resolved low coherence interferometry; RS: Raman spectroscopy