Effect of ultrasound beam angle on equine articular cartilage thickness measurement.

This study explores whether varying ultrasound beam angles would affect the measurement of cartilage thickness in horses. The results suggest that as the angle of the ultrasound beam decreases, it appears to significantly increase the measured thickness of the cartilage.

Study Design and Methodology

• The study was conducted on transverse sections of middle phalanges, a type of bone found in horses’ legs, collected post-mortem.
• The sections were imaged with a linear transducer in a water bath, closely parallel to the plane of the section. Images were taken using a variety of ultrasound beam angles: 0 degrees, 30 degrees, 45 degrees, and 60 degrees.
• After image acquisition, the thickness of the proximal articular cartilage, a type of joint cartilage, was measured both on the physical bone specimen and on the corresponding ultrasound images.

Results and Findings

• According to the findings, the thickness of the cartilage as measured on the actual bone specimens was 1.82 +/- 0.35 mm.
• The measurements taken from the ultrasound images differed depending on the ultrasound beam angle used. At 0 degrees, the thickness measured 1.72 +/- 0.29 mm; at 30 degrees, 1.99 +/- 0.34 mm; at 45 degrees, 2.06 +/- 0.34 mm; and at 60 degrees, 2.3 +/- 0.38 mm.
• There was a significant distinction between the measurements taken directly from the specimens and those received from the ultrasound images taken at 30 degrees, 45 degrees, and 60 degrees.
• Notably, as the angle of the ultrasound beam decreased, there was a substantial rise in the perceived thickness of the cartilage (P = 0.0157).

Conclusion

• The research proposes a potential inconsistency in measuring cartilage thickness using ultrasound and highlights the need to consider the ultrasound beam angle as a significant factor.
• The readability of ultrasound images might be distorted, possibly due to the different speed of ultrasound waves in cartilage compared to that presumed by ultrasound machines for distance calculations.
• This implies that ultrasound measurements of cartilage thickness might not always be reliable, which could potentially lead to misinterpretations in both veterinary and human medicine.