Table 1 Summarize of diagnostic methods and assessment techniques for TS

PFT

Swift, non-invasive estimation of obstruction presence

Limited information regarding exact location, morphology, or typology of airway stenosis

Diagnosis of normal, obstructive or restrictive pattern of lung function

CT

Comprehensive visualization of airways, including site, length and degree of stenosis

Radiation exposure risk, artifacts by respiratory movements and secretions

Imaging various body parts;

specifically for lungs, visualization of airways and 3D reconstruction

MRI

Noninvasive, no risk of radiations, Comprehensive visualization of airways including site, length and degree of stenosis

Lengthy scan, breathing artifacts

Imaging various body parts of conscious patients without breathing difficulties

US

Swift, portable, non-invasive estimation of site, length and degree of stenosis

May underestimate the absolute lumen diameter, can only measure transverse cervical tracheal diameter

Abdominal, renal, cardiovascular, breast, imaging;

for lung specifically, visualizing of glottic area and upper trachea

PAT/MSOT

Sub-millimeter spatial resolution with a penetration depth of several centimeters, High inter-observer reproducibility

Still in preclinical phase

Tumor, thyroid, cardiovascular, breast, skin, imaging

Endoscopy

Comprehensive visualization of airways including site, length and degree of stenosis

Invasive, may under or overestimates the degree of TS, Unable to visualize airway wall structure

Diagnosis and management of various airway and lung diseases, e.g., tracheal stenosis

EBUS

Resolution of 100 microns, penetration depth of 1 cm, Visualization of site, length and degree of stenosis, wall structure and tumor invasion into the airway wall

Invasive, needs direct contact with the airway wall

Stage lung tumors and diagnose mediastinal diseases

PAE

Functional optical contrast with high spatial resolution and maintains the benefits of EBUS

Invasive, requires direct contact with the airway wall, signal attenuation in cavity structures, still in preclinical phase

Intravascular, esophageal, gastrointestinal, and urogenital imaging

OCT

High resolution of 10 µm and depth penetration of 2–3 mm, focused image despite no contact with wall, real-time visualization of site, length and degree of stenosis and wall layers, applicable in conscious patients, suitable for imaging neonatal TS

Minimally invasive, higher cost

Retinal imaging, glaucoma detection, visualization of coronary arteries