Ovarian volume measurements in mice with high-resolution ultrasonography.
OBJECTIVE
The aim of our study was to evaluate the intraobserver and interobserver variability of ovarian volume measurements in mice with high-resolution 2-dimensional ultrasonography (2DUS) and 3-dimensional ultrasonography (3DUS).


METHODS
Ovaries of 10 nude mice were visualized with a small-animal ultrasound scanner and a 40-MHz probe. For each ovary, volume was measured 3 times by 2 independent readers using both 2DUS and 3DUS methods. The 2DUS method used a biplane ellipsoid model. The 3DUS method estimated the volume by integrating 10 to 12 parallel image planes of the ovary after semiautomated outlining of the boundaries. For each type of measurement, intraobserver and interobserver standard error of measurement (SEM) values and minimal detectable volume changes were calculated by analysis of variance.


RESULTS
Two-dimensional ultrasonography showed much poorer reproducibility, with higher absolute intraobserver and interobserver SEM values (0.50 and 0.61 mm3, respectively) than 3DUS (0.20 and 0.35 mm3; P < .01). Relative intraobserver and interobserver SEM values were also much higher for 2DUS (12.20% and 14.88%) than for 3DUS (5.12% and 8.97%; P < .01). The minimal volume changes that could be detected with a 95% confidence level in successive measurements by the same (or different) observers were 33.90% (41.22%) for 2DUS and 14.10% (24.87%) for 3DUS.


CONCLUSIONS
High-resolution 3DUS can provide a reliable tool for noninvasive, longitudinal ovarian volume measurements in mice.
Lyshchik
Andrej
A
Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, CCC-1118 MCN, 1161 21st Ave, Nashville, TN 37232-2675, USA. andrej.lyshchik@vanderbilt.edu
Hobbs
Stephen B
SB
Fleischer
Arthur C
AC
Khabele
Dineo
D
Son
Deok-Soo
DS
Gore
John C
JC
Price
Ronald R
RR
D000704:Analysis of Variance; D000818:Animals; D005260:Female; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D051379:Mice; D008807:Mice, Inbred BALB C; D015588:Observer Variation; D010053:Ovary / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*