Robert D. Harris MD, MPH, Presenter: Nothing to Disclose

Joo Cho MD, Abstract Co-Author: Nothing to Disclose

David H. Lam BS, Abstract Co-Author: Nothing to Disclose

William C. Black MD, Abstract Co-Author: Nothing to Disclose

Much has been published recently about point-of-care compact ultrasound (Co US), as well as a growing interest in donating/deploying these portable machines to low resource settings.  Limited data is available re the accuracy of these machines vs. conventional ultrasound (Cn US) or cart-based equipment. We designed a comparison study of the two entities for diagnostic accuracy and confidence, using multiple readers and 53 paired patient studies.

We performed  Cn US with multiple systems (GE, Philips, and Siemens) and Co US (Sonosite 180 Plus) on 53 patients. Nine blinded (to the diagnosis) experienced and novice readers interpreted the images of the same organs +/- pathology, for a total of 514 observations. Five staff radiologists, 2 residents, and 2 sonographers participated.  The patients' age, gender, BMI, and organ system(s) imaged were recorded.  Gold standard was based upon the  original US imaging study.  After the standard examination was completed, the compact US was performed by the senior author (RDH) who targeted the organ of interest. Typical cases included cholelithiasis, fatty liver, and hydronephrosis.  Image pairs were presented in random order to the blinded readers in solo reading sessions.  Diagnostic confidence was established on a 1 (low) -5 (high) scale. Statistical analysis was performed with Wilcoxon matched-pairs signed rank test and Bland-Altman test with statistical significance at p < 0.05.

The mean diagnostic accuracy for all readers was 80 vs. 70 % for Cn US vs. Co US, p< 0.0001.  The mean diagnostic confidence level was 4.4 vs. 3.5 respectively, p <0.0001.  Surprisingly, the sonographers had the highest accuracy rates for Co US.  Reader US experience had a positive correlation with accuracy rates. BMI did not adversely affect the readers accuracy or diagnostic confidence in the selected cases.

Our results showed a diagnostic superiority (13%) and confidence level (20%) of Cn US over Co US.  However, the Co US performed adequately in these selected cases, especially in light of significantly lower cost.  These results are encouraging for point of care Co US and deployment of Co US in low resource settings, if the study is interpreted by experienced sonographers/sonologists.

Compact ultrasound compares favorably, at lesser expense, to conventional ultrasound in detecting organ specific abnormalities, when the images are interpreted by trained sonographers/sonologists

Harris, R, Cho, J, Lam, D, Black, W, A Multi-Reader Comparison of Conventional (Cart-based) vs Compact Ultrasound: Diagnostic Accuracy and Diagnostic Confidence Rates with Implications for Point-of-Care Ultrasound and Deployment/Donation in Low Resource Settings.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11004251.html