Phase-locked parallel movement of diaphragm and pelvic floor during breathing and coughing-a dynamic MRI investigation in healthy females.

Introduction and Hypothesis: the aim of this pilot study was to demonstrate physiological movements of the muscular walls surrounding the abdominal cavity during breathing and coughing in healthy nulliparous women by means of real-time dynamic magnetic resonance imaging (MRI).
Methods: eight volunteers underwent MRI measurements in a 1.5-T whole body MR-scanner. Coronal and sagittal slices were acquired simultaneously to assess respiratory-related cranio-caudal movement of diaphragm and pelvic floor (PF) and concomitant changes in horizontal abdominal diameter.
Results: respective mean amplitudes of cranio-caudal movement of the right and left diaphragmatic cupolae were 15 ± 6 and 9 ± 7 mm during quiet breathing; 32 ± 15 and 28 ± 16 mm during forceful breathing; and 32 ± 13 and 28 ± 7 mm during coughing. Both diaphragm and PF moved caudally during inspiration and cranially during expiration. Abdominal diameter decreased in all eight women consistently during the expiration phase of breathing, and in five women during coughing.
Conclusions: in healthy women, real-time dynamic MRI demonstrates parallel cranio-caudal movement of the diaphragm and the PF during breathing and coughing and synchronous changes in abdominal wall diameter.