COMPARISON OF SELECTED ULTRASOUND PERFORMANCE TESTS WITH VARYING OVERALL RECEIVER GAIN AND DYNAMIC-RANGE, USING CONVENTIONAL AND MAGNIFIED FIELD-OF-VIEW

Most ultrasound (US) scanner vendors currently offer a feature that al lows a region of the ultrasound image to be magnified or zoomed. Altho ugh the methods of magnification vary among vendors, the ability to '' zoom in'' on a selected portion of the image has gained clinical accep tance. However, using this feature introduces additional steps in the quality assurance (QA) measurement procedures. No studies exist that d emonstrate the advantage of a magnified field of view (FOV) over the c onventional FOV for QA purposes. The purpose of this study was to inve stigate the influence of a magnified versus nonmagnified FOV on variou s common QA performance tests as a function of the overall receiver ga in and dynamic range. Additionally, since the performance tests are su bject to variations caused by scanner settings, sets of QC tests were recorded using several different scanner settings to investigate any c hange in the sensitivity of the QC measurements with respect to the ma gnified and nonmagnified fields of view. The lateral and axial resolut ion, slice thickness, and caliper accuracy (vertical and horizontal) a s a function of varying overall receiver gain and dynamic range, were obtained using conventional (no zoom) as well as a magnified (zoom) fi eld of view (FOV). Each measurement was performed three times by a sin gle observer using a 4 MHz ''vector'' format transducer on a single di agnostic medical ultrasound scanner. The results show no statistical s ignificance in the variability of most recorded measurements when usin g the conventional versus the magnified FOV. However, in some cases, s uch as lateral resolution, the average value measured using the magnif ied FOV was typically 0.5 mm lower than when using a conventional FOV. (C) 1998 American Association of Physicists in Medicine.