Influence of scanning frequency and ultrasonic contrast agent on reproducibility of left ventricular measurements in the mouse.
BACKGROUND
Mice are now widely used as models of cardiovascular disease. Their small size and fast heart rates are technically challenging to echocardiography. This study examined the influence of different scanning frequencies and ultrasonic contrast agent (UCA) on the accuracy and reproducibility of measurements of left ventricular (LV) structure and function.


METHODS
Normal mouse hearts (C57BL6) were imaged at 3 different scanning frequencies before and after intravenous injection of the UCA, Optison. Coronary artery ligation mice and sham-operated controls were scanned at 10-22 MHz with and without UCA.


RESULTS
Scanning frequency had no significant effect on intraobserver or interobserver variation of LV measurements in normal mice under baseline conditions. Use of UCA significantly reduced estimated ejection fraction at 10-22 MHz compared with baseline (baseline 50.8 +/- 7.6% vs UCA 39.7 +/- 7.6%; P = .03) and significantly increased values for LV cavity dimensions (eg, LV area diastole 20.74 +/- 1.20 vs 23.23 +/- 0.98 mm 2 ; P = .002). UCA significantly reduced intraobserver and interobserver variation in LV ejection fraction.


CONCLUSIONS
Scanning frequency had no significant effect on reproducibility of LV measurements in the mouse but UCA significantly reduced interobserver variation. Use of UCA could reduce the number of mice required in any given experiment to observe a statistically significant change in LV function.
Denvir
Martin A
MA
Centre for Cardiovascular Science, Department of Medical Physics, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH14 2XU, Scotland, UK. mdenvir@staffmail.ed.ac.uk
Sharif
Isam
I
Anderson
Tom
T
Webb
David J
DJ
Gray
Gillian A
GA
McDicken
William N
WN
D000418:Albumins; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D003331:Coronary Vessels / Q000000981:diagnostic imaging; D004452:Echocardiography / Q000379:methods*; D005466:Fluorocarbons; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000187:drug effects; D008026:Ligation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D015588:Observer Variation; D009929:Organ Size / Q000187:drug effects; D015203:Reproducibility of Results; D012107:Research Design; D013318:Stroke Volume / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects
D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons