Acoustic Quantification (AQ) is a technique based on analysis of ultrasonic integrated backscatter. It enables a real time detection of blood-tissue borders and numbers the end-diastolic and end-systolic areas throughout the cardiac cycle. AQ added to the 2D image therefore offers an on-line estimate of global ventricular function in the operating room. Since AQ is dependent on a good 2D image as well as adjustment of both transmit- and time gain control the question arises whether this leads to a different assessment, compared to the 2D image only, of off-line assessment of regional left ventricular wall motion (LVWM). Twenty-three consenting patients scheduled for elective coronary bypass grafting were studied. A total of 31 observations were performed and divided into 21 short axis and 10 three chamber long axis views. Regional LVWM score was assessed off-line (video recordings postoperatively) by two independent readers on two occasions. There was no intra-reader difference in assessment of regional LVWM in the short axis view when AQ was added to the 2D image. On the other hand, the interreader difference was highly significant both without and with AQ (P = 0.0001) in this view. In the long axis view the intra-reader difference was significant (P = 0.0008 and P = 0.004 respectively), while the inter-reader difference was non-significant. However, the overall intra-reader and inter-reader agreement was 78% or higher except for the intra-reader difference in the long axis view.(ABSTRACT TRUNCATED AT 250 WORDS)