Tissue harmonic imaging improves organ visualization in trauma ultrasound when compared with standard ultrasound mode.
The focused abdominal sonography for trauma (FAST) examination is complicated by brightly lit trauma bays, limited time, and body habitus. Recently, new ultrasound (US) technology has become available that improves organ visualization in abdominal scans.


OBJECTIVE
The hypothesis was that a new US mode, tissue harmonic (TH) imaging, improves visualization of critical organ relationships in the FAST examination by making use of previously unused frequencies. The authors performed a blind, prospective observational study to compare the images obtained in typical FAST views with those obtained in standard US and TH modes.


METHODS
Blunt trauma patients presenting to a level I trauma center between April and September 2000 were enrolled on a convenience basis. Typical FAST views were obtained in standard and TH modes. The emergency ultrasonographer (EU) switched between modes for each view, optimizing the gain each time. Multiple digital still images were made with all indications of the mode used disguised. For each view on a patient, the best image in each mode was selected in a blinded fashion. Three experienced EUs, blinded to the mode used, rated each image pair for resolution, detail, and total image quality as previously defined on a ten-point Likert scale, 10 being the best for each category. Wilcoxon signed-ranks test, 95% confidence intervals (95% CIs), and interobserver correlation were calculated.


RESULTS
A total of 76 image groups (39 of Morison's pouch, 20 splenorenal, and 17 bladder) from 52 patients were rated. Tissue harmonics produced improved resolution, detail, and quality when compared with the standard US mode, with median scores of 6.7 vs. 6.0, 6.7 vs. 6.0, and 6.3 vs. 6.0, respectively. The differences of 0.7 (95% CI = 0.4 to 0.93), 0.7 (95% CI = 0.4 to 0.93), and 0.33 (95% CI = 0.17 to 0.67) were statistically significant, with p = 0.0001, 0.0001, and 0.0003, respectively. There was good interobserver agreement (kappa = 0.74; 95% CI = 0.68 to 0.79).


CONCLUSIONS
Tissue harmonics produced FAST images higher in detail, resolution, and total image quality than standard-mode US images.
Blaivas
Michael
M
Department of Emergency Medicine, North Shore University Hospital, Manhasset, NY 11030, USA. blaivas@pyro.net
DeBehnke
Daniel
D
Sierzenski
Paul R
PR
Phelan
Mary Beth
MB
D000006:Abdomen, Acute / Q000175:diagnosis / Q000000981:diagnostic imaging*; D016001:Confidence Intervals; D004636:Emergency Service, Hospital; D004638:Emergency Treatment / Q000379:methods; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D015601:Injury Severity Score; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D018709:Statistics, Nonparametric; D015599:Trauma Severity Indices; D014463:Ultrasonography / Q000379:methods*; D014949:Wounds, Nonpenetrating / Q000175:diagnosis / Q000000981:diagnostic imaging*