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Authors' response to assessment of intraparenchymal lung collateral ventilation
  1. Helen Marshall1,
  2. Rod Lawson2,
  3. Jim M Wild1
  1. 1Department of Academic Radiology, University of Sheffield, Sheffield, South Yorkshire, UK
  2. 2Respiratory Medicine, Sheffield Teaching Hospitals NHS Trust, South Yorkshire, UK
  1. Correspondence to Professor Jim M Wild, Department of Academic Radiology, University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK; j.m.wild{at}

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We thank the writers of the letter1 for their interest and agree that the potential placement of this novel imaging method in the planning of patient treatment, such as bronchoscopic and surgical lung volume reduction, is not yet determined.

The example of collateral ventilation shown in figure 2 of our paper2 is intersegmental, however, 3He MRI is able to visualise both interlobar and intralobar collateral and delayed ventilation. The technique images gas as it moves within the lung whether it traverses lobar or segmental boundaries.

Interlobar lung fissure condition and emphysema type are anatomical radiological markers, and while structure is important there are risks to predicting function from form alone. The assessment of collateral and delayed ventilation pathways with hyperpolarised gas MRI is intrinsically functional because we directly visualise the gas itself.

For further information about a region being considered for bronchoscopic lung volume reduction, time-resolved 3He MRI could be used in conjunction with 1H blood perfusion MRI3 to assess ventilation–perfusion matching, and with 3He diffusion MRI4 to measure emphysematous destruction at the acinar level.

More research is needed to determine if hyperpolarised gas MRI reliably correlates with catheter measurements in treatment planning, and we look forward to exploring such studies in the future, and welcome this correspondence.


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  • Competing interests None.

  • Ethics approval Ethics approval was provided by South Yorkshire REC (REC reference: 10/H1310/11).

  • Provenance and peer review Not commissioned; internally peer reviewed.