ChestLive data

CT Chest (High-Resolution)

High-resolution CT of the chest uses thin-section, high-spatial-frequency reconstruction to characterize the pulmonary interstitium and small airways in exquisite detail. It is the reference imaging test for diffuse parenchymal (interstitial) lung disease, bronchiectasis, and emphysema, often allowing a confident pattern-based diagnosis such as usual interstitial pneumonia (UIP). Complementary prone and expiratory images distinguish dependent atelectasis from disease and reveal air trapping.

Indications

Suspected interstitial lung disease and characterization of a diffuse parenchymal pattern (e.g., UIP, NSIP, HP)
Bronchiectasis assessment and evaluation of chronic productive cough
Quantification and distribution of emphysema
Suspected hypersensitivity pneumonitis, sarcoidosis, or occupational/connective-tissue lung disease
Unexplained dyspnea with restrictive pulmonary function or reduced diffusing capacity
Small-airways disease and suspected air trapping (expiratory imaging)

Contraindications & Cautions

No absolute contraindication; the standard protocol is non-contrast
Pregnancy: justify and use dose reduction; the low-dose HRCT technique limits fetal scatter dose
Radiation stewardship in young patients and for serial follow-up; use low-dose protocols and iterative reconstruction
Inability to perform breath-holds or follow inspiratory/expiratory commands degrades the study
If iodinated contrast is later required for another indication, screen renal function and allergy history

Patient Preparation

No fasting or IV access required for a standard non-contrast HRCT
Coach breath-hold technique: full suspended inspiration for supine images
Position supine, arms above the head; add prone imaging when posterior dependent opacity is present
Explain expiratory acquisition and rehearse the maneuver for air-trapping assessment
Remove radiopaque garments and monitoring leads from the field where possible
Confirm the clinical question and any prior imaging for comparison

Technique & Parameters

Volumetric thin-section acquisition, 0.625-1.25 mm collimation, reconstructed with a sharp/high-spatial-frequency kernel
Full-inspiration supine helical acquisition covering lung apices to costophrenic angles
Prone thin-section images to resolve dependent atelectasis from early fibrosis
Expiratory images (end-expiration) to detect mosaic attenuation and air trapping
Typically 120 kVp with dose modulation; low-dose protocols for follow-up; no IV contrast
Review on lung (W1500/L-600) and mediastinal windows; use MIP for micronodules and minIP for mosaicism/emphysema

Systematic Review

Determine the axial distribution: upper vs lower zone, central vs peripheral/subpleural
Characterize the dominant pattern: reticular, nodular, ground-glass, cystic, or low-attenuation
Assess for honeycombing and traction bronchiectasis indicating established fibrosis
Evaluate the airways for bronchial dilatation, wall thickening, and mucous plugging
Look for mosaic attenuation and confirm air trapping on expiratory images
Review the mediastinum and hila for lymphadenopathy; check for pleural and pericardial disease
Inspect for nodules, and correlate distribution (perilymphatic, centrilobular, random)

Key Findings & Significance

Honeycombing with basal, subpleural predominance and traction bronchiectasis: UIP pattern (e.g., IPF)
Ground-glass opacity with subpleural sparing and reticulation: NSIP pattern
Centrilobular ground-glass nodules, mosaic attenuation, and air trapping: hypersensitivity pneumonitis
Upper-lobe perilymphatic nodules with symmetric hilar/mediastinal nodes: sarcoidosis
Cylindrical/varicose/cystic bronchial dilatation with signet-ring sign: bronchiectasis
Low-attenuation areas without walls (centrilobular) or with walls (paraseptal): emphysema subtypes
Crazy-paving (ground-glass with superimposed septal thickening): broad differential including infection and alveolar proteinosis

Differential Considerations

UIP pattern: idiopathic pulmonary fibrosis vs chronic HP vs connective-tissue disease vs asbestosis
Cystic lung disease: LAM vs Langerhans cell histiocytosis vs lymphoid interstitial pneumonia vs Birt-Hogg-Dube
Mosaic attenuation: small-airways disease (air trapping) vs vascular (chronic PE) vs ground-glass infiltration
Upper-lobe fibrosis: sarcoidosis vs chronic HP vs pneumoconiosis vs prior TB/radiation
Ground-glass opacity: infection/edema (acute) vs NSIP, DIP, or alveolar proteinosis (subacute/chronic)
Perilymphatic nodules: sarcoidosis vs lymphangitic carcinomatosis vs silicosis

Pearls & Pitfalls

Prone imaging is essential to avoid overcalling dependent atelectasis as early fibrosis
Expiratory scans confirm air trapping; without them, mosaic attenuation is nonspecific
Traction bronchiectasis within ground-glass indicates fibrosis, changing the interpretation
Follow current IPF diagnostic guidelines for confident UIP versus probable/indeterminate patterns
Micronodule distribution (perilymphatic vs centrilobular vs random) is the key to the differential
Correlate with occupational, drug, and connective-tissue history; imaging pattern alone is often insufficient

Structured Report

State protocol (inspiratory, prone, expiratory) and comparison studies
Describe the dominant pattern, its zonal and axial distribution, and extent
Report presence or absence of honeycombing, traction bronchiectasis, and air trapping explicitly
Comment on airways, nodules, mediastinal/hilar nodes, and pleura
Assign a diagnostic pattern (e.g., typical UIP, probable UIP, indeterminate, alternative) per current criteria
Impression: give the most likely diagnosis or narrowed differential and recommend MDT discussion or biopsy where appropriate

References

ATS/ERS/JRS/ALAT Clinical Practice Guideline: Diagnosis of Idiopathic Pulmonary Fibrosis (2018/2022 update)
Fleischner Society: Glossary of Terms for Thoracic Imaging
ACR Appropriateness Criteria: Diffuse Lung Disease
Webb, Muller, Naidich: High-Resolution CT of the Lung

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

CT Chest (High-Resolution)

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References