Kai Nassenstein, Presenter: Nothing to Disclose

Stephan Orzada MSc, Abstract Co-Author: Nothing to Disclose

Lars Haering, Abstract Co-Author: Nothing to Disclose

Andreas Czylwik, Abstract Co-Author: Nothing to Disclose

Thomas W. Schlosser MD, Abstract Co-Author: Nothing to Disclose

Oliver Bruder, Abstract Co-Author: Nothing to Disclose

Mark E. Ladd PhD, Abstract Co-Author: Nothing to Disclose

Stefan Maderwald, Abstract Co-Author: Nothing to Disclose

Recently phonocardiogram (PCG) gating has been introduced as alternative to ECG-gating for cardiac MR due to its intrinsically insensitivity to magneto-hydrodynamic effects which hamper ECG-gating at higher field strengths. So far, PCG-gating had not been validated in patients. Therefore our study aimed, to evaluate PCG-gated cine imaging for the assessment of global and regional left ventricular (LV) function in clinical routine.

79 consecutive patients were examined on a 1.5 T scanner. For PCG-gating an in-house developed acoustic triggering device was used, which was composed of an optoacoustic microphone (Optoacoustics, Israel) containing no conductive parts and a DSP card (dSpace, Germany) for signal detection, filtering against acoustic noise (e.g. gradients), and trigger generation. Cine imaging of the LV was performed twice in randomised order by using a retrospectively PCG- and a retrospectively ECG-gated cine steady state free precession sequence (TR 2.63 ms, TE 1.12 ms, FA 72°). End-diastolic volumes (EDV), end-systolic volumes (ESV), stroke volumes (SV), ejection fraction (EF), muscle mass (MM), as well as regional wall motion were assessed for both datasets. Subgroup analyses were performed for patients with valvular defects and for patients with cardiac dysrhythmia since both subgroups might be critical for PCG-gating.

PCG-gated cine imaging was feasible in 75 (95%) patients. Excellent correlations were observed for all volumetric parameters derived from both datasets (r>0.98 for all variables analysed). No significant differences were observed for EDV (-0.24±3.14 ml, p=0.51), ESV (-0.04±2.36 ml, p=0.90), SV (-0.20±3.41 ml, p=0.61), EF (-0.16±1.98%, p=0.49), or MM (0.31±4.2 g, p=0.71) for the entire study cohort, nor for the subgroups of patients with valvular defects or with dysrhythmia. PCG- and ECG-gated cine imaging revealed similar results for regional wall motion analyses (115 vs. 119 segments with wall motion abnormalities, p=0.37).

The present study demonstrates that PCG-gated cine imaging enables accurate assessment of global and regional LV function in the vast majority of patients in clinical routine.

PCG gated imaging is from clinical interest due to its insensitivity to magneto-hydrodynamic effects which allows CMR at ultra-high field strengths and at lower field strengths due to its ease of use.

Nassenstein, K, Orzada, S, Haering, L, Czylwik, A, Schlosser, T, Bruder, O, Ladd, M, Maderwald, S, Cardiac MRI: Evaluation of Phonocardiogram-gated Cine Imaging for the Assessment of Global and Regional Left Ventricular Function in Clinical Routine.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11004181.html