The lateral approach water bath: A novel method of ultrasound imaging of the hand

Traditional water baths for ultrasound exams place a hand into a pan of water and submerge an ultrasound probe into the water. While this improves ultrasound transmission and moves structures into the focal zone to make higher resolution images, this method does have limitations. Patients must be manipulated directly under the probe, which can be limited by pain or normal movement restrictions. The probe must also be held very still in water to minimize motion artifact. The lateral approach water bath method addresses such limitations by imaging through the side of a thin-walled plastic container without submerging the probe. This reduces much need for patient manipulation by imaging through the side of a column-shaped bath, which has 360 degrees of imaging freedom. It also stabilizes the probe directly against the flat, firm container to reduce image degrading motion artifact. We hypothesized that because of these improvements the lateral approach water bath might create higher quality images than traditional water baths.

We compared twenty images from each method, which were obtained with the same model and ultrasound operator at the same time. Two ultrasound fellowship trained blinded reviewers rated the images for quality and adequacy for clinical decision making on a scale from 1 to 5.

Image quality was better for the lateral water bath, with an average rating of 4.2 compared to the traditional bath's 2.6 (p < 0.001). Adequacy to aid clinical decision making was better for the lateral approach bath with an average rating of 4.0 compared to the traditional bath's 2.6 (p < 0.001). The lateral bath also had a smaller range for image quality and thus greater consistency.

The lateral approach water bath is a method of hand imaging that produces higher quality, more consistent, and more clinically useful images than traditional water bath imaging.