skip

HRCT Technique

HRCT  Technique

HRCT  Technique

CT scan play a key role in the different stages of care for chronic interstitial lung diseases1.

Its role is essential for reaching positive & aetiological diagnoses, assessing lesions, monitoring changes, screening for complications, and assessing prognosis1.

The aetiological diagnosis is based on recognition of the elementary signs and the dominant one among them, as well as the detection of pulmonary and lobular abnormalities. The combination of these morphological and topographical data can identify CT patterns leading to a significant reduction in the number of differential diagnoses at 2 or 3, and to guide the techniques allowing, if necessary, a diagnosis of certainty (bronchoalveolar lavage; surgical lung biopsy, cryobiopsy…).

Given the importance of CT scan in diagnosing chronic ILD, high-quality CT images should be obtained2.

The requisite conditions for conducting a chest CT scan when ILD is suspected are summarised in the table opposite3.

  • CT scan without injection of contrast medium

  • Number of acquisitions:

    • Supine: inspiratory at full inspiration (volumetric acquisition)

    • Supine: inspiratory at full inspiration (volumetric acquisition)

  • Cross section thickness ≤ 1,5 mm

  • Reconstruction field focused on the lungs

  • Acquisition in line with European radiation standards

  • Archiving of acquisitions in thin-cross-sections on CD/DVD for rereading at a later date

  • Coronal and sagittal reconstructions if volumetric acquisitions are available
  • Sagittal reconstructions in minimal intensity projection mode (minIP) at a thickness of 5 to 8 mm
  • Axial/coronal/sagittal* reconstructions in maximum intensity projection mode (MIP) at a thickness of 5 to 8 mm
  • Expiratory scans to detect lobular air trapping

References

References

  1. Collège des Enseignants de Pneumologie. Item 206 (ex item 120). Pneumopathies interstitielles diffuses. 2013

  2. Cottin V, et al. French practical guidelines for the diagnosis and management of idiopathic pulmonary fibrosis - 2017 update. Full-length version. Rev Mal Respir 2017;34:900-68

  3. Raghu G, et al. Diagnosis of Idiopathic Pulmonary Fibrosis. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med 2018;198:e44-e68