Doppler ultrasound in mice.
Stypmann J.
Department of Cardiology and Angiology, Hospital of the University of Munster, Germany.

• > Color, power, spectral, and tissue Doppler have been applied to mice. Due to the noninvasive nature of the technique, serial intraindividual Doppler measurements of cardiovascular function are feasible in wild-type and genetically altered mice before and after microsurgical procedures or to follow age-related changes. Fifty-megahertz ultrasound biomicroscopy (VisualSonics, Vevo® micro-ultrasound systems) allows to record the first beats of the embryonic mouse heart at somite stage 5, and the first Doppler-flow signals can be recorded after the onset of intrauterine cardiovascular function at somite stage 7. Using 10- to 20-MHz ultrasound transducers in the mouse embryo, cardiac, and circulatory function can be studied as early as 7.5 days after postcoital mucous plug. Postnatal Doppler ultrasound examinations in mice are possible from birth to senescent age. Several strain-, age-, and gender-related differences of Doppler ultrasound findings have been reported in mice. Results of Doppler examinations are influenced by the experimental settings as stress testing or different forms of anesthesia. This review summarizes the present status of Doppler ultrasound examinations in mice and animal handling in the framework of a comprehensive phenotype characterization of cardiac contractile and circulatory function.
  
  NOTE: While there are many references to the VisualSonics system (“Ultrasound biomicroscopy”), the references and examples cites are from our first generation instruments. The current instrument model, the Vevo 770, still provides the same quality is spatial resolution (down to 30 microns) yet has significantly improved temporal resolution - - with frame rates up to 240 Hz and up to 1,000 Hz using EKV™, a parented line-based reconstruction technique for extremely high temporal resolution micro-imaging. In addition, there are a variety of new applications available including TDI (tissue Doppler imaging), semi-automated segmentation and measurement, an extensive cardiovascular measurement and annotation package, integration of third-party blood pressure signals with the Vevo high-resolution imaging and the recent introduction of MicroMarker™, optimized contrast agent kits for performing image enhancement, relative tumor perfusion studies, myocardial viability and infarction studies and targeted molecular imaging.