Simultaneous cardiac and respiratory synchronization in oxygen-enhanced magnetic resonance imaging of the lung using a pneumotachograph for respiratory monitoring

Invest Radiol. 2006 May;41(5):476-85. doi: 10.1097/01.rli.0000208240.08299.5d.

Abstract

Objectives: We sought to evaluate an optimized method for oxygen-enhanced magnetic resonance imaging of the lung, using electrocardiogram-trigger and a pneumotachograph for simultaneous cardiac and respiratory synchronization.

Materials and methods: Five series of IR-SSFSE images (echo time = 28.2 milliseconds; inversion time = 1,200 milliseconds) were obtained in 6 volunteers during the ventilation-paradigm room-air/oxygen/room-air: series 1, respiratory-triggered; series 2, cardiac-triggered; series 3, cardiac-triggered and respiratory-synchronized using the signal of the pneumatic belt; series 4, cardiac-triggered and respiratory-synchronized using the external signal of the pneumotachograph; and series 5, not cardiac-triggered and respiratory-synchronized using the signal of the pneumotachograph. Standard deviations of the lung (SI(var)) and diaphragm mismatch (DM) were measured. The relative SI change (DeltaSI) was computed from room-air and oxygen-enhanced images. Parametric maps were obtained from cross-correlation analysis of the ventilation paradigm. Mean correlation coefficients (cc) and the percentage of activated pixels over the lung (Act%) were calculated from these maps. All 5 parameters were compared among the 5 series (Friedman-analysis of variance, Dunn's posthoc test).

Results: In series 4, DM and SI(var) were significantly lower than in respiratory and cardiac-triggered series (DM = 4.7 vs. 14.3 and 18.4; SI(var) = 4.9 vs. 10 and 11). In the same series cc and Act% also were significantly higher than in series 1 and 2 (cc = 0.86 vs. 0.7 and 0.6; Act% = 71.3 vs. 44.7 and 41.2). DeltaSI was not significantly different among all series.

Conclusions: Effective respiratory and cardiac synchronization can be achieved in oxygen-enhanced magnetic resonance imaging of the lung, using a pneumotachograph for real-time targeting of end-expiration.

MeSH terms

  • Adult
  • Contrast Media / administration & dosage*
  • Diagnostic Techniques, Respiratory System / instrumentation
  • Electrocardiography
  • Female
  • Heart Rate
  • Humans
  • Image Processing, Computer-Assisted
  • Lung / anatomy & histology*
  • Lung / physiology
  • Magnetic Resonance Imaging / methods*
  • Male
  • Oxygen / administration & dosage*
  • Respiration*

Substances

  • Contrast Media
  • Oxygen