This week we are focusing on the use of a particular ‘subtype’ of ultrasonography within a research-based context. Utilising three-dimensional (3D) ultrasound relative to two-dimensional (2D) ultrasound imaging, the paper we are looking at this week will assess the use of ultrasonography in relation to the canine gallbladder. The paper is titled ‘Evaluation of gallbladder volume and contraction index with three-dimensional ultrasonography in healthy dogs’ by Rahmani V et al., The Journal of Veterinary Medical Science, April 23rd 2015 (ahead of print). The 10 dogs used in this study were between 2-5 years old and were considered healthy. In order to assess the gallbladder, measurement of volume and contraction was carried out before and after fasting, following the consumption of full-fat milk which would allow the gallbladder to contract.

To begin, it should be noted that as is almost always the case with research studies, there were some limitations that the researchers had to work around. In this case, it was not possible to reliably assess whether 2D and 3D ultrasound imaging returned reliable gallbladder volume measurements following examination (i.e. there were no baseline measurements to compare results to), which explains why comparisons were drawn between the type of ultrasound application (2D vs 3D) carried out. The researchers explain that this is something they hope to address in further studies.

Prior to feeding, differences between 2D and 3D ultrasound imaging were already apparent – the volume of the gallbladder following the latter type of ultrasonography was shown to be greater, whereas 3D ultrasonography also showed a relative significant reduction in gallbladder volume following milk consumption in comparison to pre-feeding. In contrast, the relative volumes following assessment by 2D imaging did not reach significance.  The question of why 3D ultrasound imaging returned better results can thus be asked. This paper reveals how 2D ultrasound imaging can retrieve ‘only…longitudinal and transverse views’ and may have limitations when taking the subjects weight into account, which may start to address the issue stated above. In contrast 3D ultrasound imaging also allows the coronal view to be captured, which may offset any weight issues previously described.

It is interesting to speculate on the future of 3D ultrasound imaging within the veterinary world, and specifically as a tool by which to assess the gallbladder. The answer lies in continual studies that must be carried out. If you would like information on anything ultrasound-related, please do not hesitate to contact us.