Patrick L. Von Behren

Dynamic measurement of parameters within a sequence of images

A method of dynamically measuring parameters within a series of images using image processing is disclosed. A sequence of ultrasound images is generated by means of an ultrasound system. A user determines at least one region of interest within a first image. Then, at least one parameter for each region of interest is evaluated, e.g. the number of pixels exceeding a pre-defined intensity are counted. A new region of interest within a sequential image is searched within a search area around the predefined region of interest which best matches the region of interest. This is done for all images of a sequence whereby the new region of interest which best matches the region of interest of the previous image is used as a region of interest for the following image.

Lower receiving frequencies than transmitting frequencies could yield improved results for contrast imaging: An in vivo study in closed chest canines

Background: Ultrasonic imaging methods of receiving at higher frequencies, which are multiples of the transmitting frequencies (harmonic imaging), are well established as a means of improving myocardial visualization in association with intravenous contrast administration. This exploratory study examined the effect of using receive frequencies that were lower than the transmit frequencies while imaging closed chest dogs with an Ensemble wideband, phase inversion contrast program on a modified Siemens Elegra scanner. Methods: Intravenous bolus injections of 0.75 mL Definity and 1 mL QW7437 were administered to six anesthetized dogs. Intermittent imaging for contrast visualization was performed using either a broadband array, transmitting at 1.4 MHz and receiving at 2.6–3.2 MHz or a broadband 4–7.5 MHz transducer transmitting at 6.0 MHz and receiving at 4.2–4.5 MHz. Contrast enhancement was measured by videodensitometry, sampling mid‐cavity and within the myocardium before and after injection. The changes in videodensity from control to after injection were calculated for each method. Results: There was no significant difference in the change in intracavity videodensity between the two imaging strategies although there was near full intracavity saturation in all cases. However, the change in myocardial density was significantly greater for both contrast agents when using receiving frequencies lower than transmitting frequencies (P = 0.02 and 0.03). The difference in duration of the myocardial blush did not reach statistical significance but it tended to persist for longer with the lower receiving frequencies. Conclusion: Delivering sound energy at a slightly higher frequency and receiving at lower than the transmit frequency may be an advantageous method of enhancing myocardial perfusion signals during intravenous contrast echocardiography. (ECHOCARDIOGRAPHY, Volume 20, April 2003)