Ultrasound image quality comparison between an inexpensive handheld emergency department (ED) ultrasound machine and a large mobile ED ultrasound system

Questions have been raised regarding image quality (IQ) provided by portable ultrasound (US) machines. Objectives To determine if a difference exists between images obtained with a common portable US machine and those obtained with a more expensive, larger US machine when comparing typical views used by emergency physicians. Methods The authors performed a cross-sectional, blinded comparison of images from similar sonographic windows obtained on healthy models using a SonoSite 180 Plus and a General Electric (GE) 400 US machine. Both machines were optimized by company representatives. Images obtained included typical abdominal and vascular applications using the abdominal and linear transducers on each machine. All images were printed on identical high-resolution printers and then digitized using a bitmap format at 300 dots-per-inch resolution (RES). Images were then cropped, masked, and placed into random order comparing each view per model by a commercial Web design company (loracs.com). Three credentialed emergency physician sonologists, blinded to machine type, rated each image pair for RES, detail (DET), and total IQ as previously defined in the literature using a ten-point Likert scale; 10 was the best rating for each category. Paired t-test, 95% confidence intervals (95% CIs), and interobserver correlation were calculated. Results A total of 49 image pairs were evaluated. Mean GE 400 RES, DET, and IQ scores were 6.8, 6.8, and 6.6, respectively. Corresponding SonoSite means were 6.3, 6.3, and 6.0, respectively. The difference of 0.5 (95% CI=0.13 to 1.1) for DET was not statistically significant (p=0.06). The differences of 0.5 (95% CI=0.1 to 1.1) and 0.6 (95% CI=0.2 to 1.2) for RES and IQ were statistically significant, with p=0.01 and 0.01. There was good interobserver agreement (κ=0.71; 95% CI=0.67 to 0.78). Conclusions A statistically significant difference was seen between GE 400 and SonoSite in IQ and RES, but not DET.