Transesophageal Ultrasound Using a Narrow Probe

Abstract

Transesophageal echocardiography is implemented using a miniature transversely oriented transducer that is preferably small enough to fit in a 7.5 mm diameter probe, and most preferably small enough to fit in a 5 mm diameter probe. Signal processing techniques improve the depth of penetration to the point where the complete trans-gastric short axis view of the left ventricle can be obtained, despite the fact that the transducer is so small. The reduced diameter of the probe (as compared to prior art probes) reduces risks to patients, reduces or eliminates the need for anesthesia, and permits long term direct-visualization monitoring of patients' cardiac function.

We claim: 
     
         1 . A system for imaging regions that include at least two types of tissue, the system comprising:
 an ultrasound imaging system; and   a probe including (a) a housing having a distal end and a flexible shaft, (b) an phased array ultrasound transducer mounted in the distal end of the housing, the transducer being made of a stack of piezo element spaced at a pitch between 125 and 128 μm with a kerf of less than 30 μm, and (c) an interface that operatively connects the ultrasound transducer to the ultrasound imaging system such that the ultrasound imaging system drives the ultrasound transducer and receives return signals from the ultrasound transducer,   wherein the distal end has an outer diameter of less than 7.5 mm and the flexible shaft has an outer diameter of less than 7.5 mm, wherein the transducer is operated at between 6 and 7.2 MHz, and wherein the ultrasound transducer is configured to emit a fan-shaped beam with a sector width of 60° or less.   
     
     
         2 . The system of  claim 1 , wherein the distal end has an outer diameter of less than 6 mm. 
     
     
         3 . The system of  claim 1 , wherein the distal end has an outer diameter of about 5 mm. 
     
     
         4 . The system of  claim 1 , wherein the transducer is operated at 6.16 MHz.