HIGH-FREQUENCY ULTRASOUND - DETERMINATION OF THE LOWEST FREQUENCY REQUIRED FOR CELLULAR IMAGING AND DETECTION OF MYOCARDIAL-DISEASE

We have previously demonstrated that a 600 MHz transducer enables the visualization of cellular detail in specimens of myocardium. However, lower-frequency transducers are more practical and provide better tiss ue penetration fbr possible in vivo application of this technique. thi s study was designed to ascertain the lowest frequency at which cellul ar detail can be imaged. We performed ultrasound imaging of 5 mu m sec tions of 14 samples of myocardium. Each specimen was examined serially with 600 MHz, 400 MHz, 200 MHz, and 100 MHz transducers. Normal cardi ac myocytes and pathologic phenomena such as fibrosis, cell fallout, a nd round cell infiltration were clearly identified with a 600 MHz tran sducer. Although there was a slight decrease in resolution, normal and pathologic phenomena were also identified with 400 and 200 MHz transd ucers. However, cellular detail could not be adequately identified wit h a 100 MHz transducer. In conclusion, transducer frequencies of 600 t o 200 MHz enable visualization of cell detail and detection of patholo gic changes in the myocardium. A transducer frequency of at least 200 MHz is probably required for possible in vivo application of this tech nique.