Quantitative analysis of antral follicle number and size: a comparison of two-dimensional and automated three-dimensional ultrasound techniques.

OBJECTIVE: To compare two-dimensional (2D) ultrasound to automated three-dimensional (3D) ultrasound for the measurement of antral follicle number and size. METHODS: 24 subjects aged <40 underwent transvaginal ultrasound (Voluson E8) in the early follicular phase of menstrual cycle. A 2D ultrasound scan of both ovaries was performed and each antral follicle identified and then measured by taking the mean of two diameters. A 3D ultrasound dataset of both ovaries was then acquired and analysed using "Sonography-based Automated Volume Count" (SonoAVC). The time taken to measure the size of all antral follicles in both ovaries was recorded in seconds for each technique. The antral follicle counts were then grouped into categories according to size: 2.0-5.0 mm, 2.0-6.0 mm, 2.0-8.0 mm, 2.0-9.0 mm, and 2.0-10mm. Limits of agreement (LOA) and a paired t-test or Wilcoxon signed ranks test was used to analyse the data dependent on its distribution. RESULTS: The AFC in all the categories was significantly lower with SonoAVC than with 2D ultrasound (p<0.05). When antral follicles were compared for every mm size, 2D ultrasound measured more follicles measuring 3.0-3.99mm (4.11+/-3.70 vs 2.63+/-2.31; P=0.019) and 4.0-4.99mm (4.63+/-4.86 vs 2.68+/-2.89; P=0.013) than those measured with SonoAVC. LOA were widest with follicles measuring 3.0-3.99mm(6.38 and -3.43) and 4.0-4.99mm(7.99 and -4.09). SonoAVC took significantly lesser time to measure the number and size of the antral follicles than 2D ultrasound (132.05+/-56.23 vs 324.47+/-162.22; p<0.001). CONCLUSION: Fewer antral follicles are evident overall when SonoAVC is used to analyse 3D ultrasound data. The clinical value of this remains to be determined but the automated technique is significantly quicker than measures made using 2D ultrasound which may also overestimate the number and size of follicles. Copyright (c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.