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Diaphragmatic and cardiac motion during suspended breathing: preliminary experience and implications for breath-hold
A E Holland1, J W Goldfarb, R R Edelman
1Department of Radiology, University Hospital Nijmegen, The Netherlands.
Purpose:
To investigate and quantify motion of the diaphragm and heart during suspended breathing at end inspiration and end expiration.
Materials And Methods:
In 10 healthy adult volunteers, line scanning was performed to monitor the position of the diaphragm during a breath hold at end inspiration and end expiration, with a spatial and temporal resolution of 0.25 mm and 200 msec, respectively. Electrocardiographically gated, turbo fast low-angle shot (FLASH) magnetic resonance (MR) imaging was performed to monitor movement of the diaphragm and heart.
Results:
During a breath hold, the diaphragm moved upward. At end expiration, the velocity of the diaphragm during suspended breathing was constant (mean, 0.15 mm/sec). At end inspiration, motion of the diaphragm during suspended breathing was more complex (range, 0.1-7.9 mm/sec). During a 20-second breath hold, mean displacement of the diaphragm was 25% of that during normal breathing. FLASH MR imaging revealed variations in the position of the heart during a breath hold. During suspended respiration, the heart did not return to the same position on consecutive heartbeats and, consequently, the margins of the heart typically moved inward.
Conclusion:
Breath holding does not eliminate motion of the diaphragm. Changes in the motion of the diaphragm and transthoracic pressure during a breath hold result in complex movement of the heart and may cause blurring during breath-hold MR imaging.