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.

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 ultrasound transducer mounted in the distal end of the housing, and (c) an interface that operatively connects the ultrasound transducer to the ultrasound imaging system so that the ultrasound imaging system can drive the ultrasound transducer and receive return signals from the ultrasound transducer,   wherein the distal end has an outer diameter of less than about 7.5 mm and the flexible shaft has an outer diameter of less than about 7.5 mm, and wherein the depth of penetration is at least about 15 times the azimuthal aperture of the transducer.   
     
     
         2 . The system of  claim 1 , wherein the shaft has an outer diameter of less than about 6 mm and the distal end has an outer diameter of less than about 6 mm. 
     
     
         3 . The system of  claim 2 , wherein the transducer is transversely oriented. 
     
     
         4 . The system of  claim 1 , wherein the distal end has an outer diameter of about 5 mM. 
     
     
         5 . The system of  claim 4 , wherein the transducer is transversely oriented. 
     
     
         6 . The system of  claim 1 , wherein the shaft has an outer diameter of less than about 6 mm and the distal end has an outer diameter of less than about 6 mm, wherein the transducer is a transversely oriented phased-array transducer with a size in the elevation direction of at least about 6 mm, and wherein the ratio of the elevation size of the transducer to the azimuthal size of the transducer is at least about 1.5:1. 
     
     
         7 . The system of  claim 6 , wherein the depth of penetration is at least about 20 times the azimuthal aperture of the transducer. 
     
     
         8 . The system of  claim 1 , wherein the shaft has an outer diameter of between about 2.5 and 4 mm and the distal end has an outer diameter of between about 2.5 and 4 mm. 
     
     
         9 . The system of  claim 8 , wherein the transducer is transversely oriented. 
     
     
         10 . The system of  claim 1 , wherein the shaft has an outer diameter of between about 2.5 and 4 mm and the distal end has an outer diameter of between about 2.5 and 4 mm, wherein the transducer is a transversely oriented phased-array transducer with a size in the elevation direction of at least about 3 mm, and wherein the ratio of the elevation size of the transducer to the azimuthal size of the transducer is at least about 1.5:1. 
     
     
         11 . The system of  claim 10 , wherein the depth of penetration is at least about 20 times the azimuthal aperture of the transducer. 
     
     
         12 . A system for transesophogeal ultrasound imaging of a heart of a patient comprising:
 an ultrasound imaging system; and   a probe including (a) a housing having a distal end and a flexible shaft, (b) an ultrasound transducer mounted in the distal end of the housing, and (c) an interface that operatively connects the ultrasound transducer to the ultrasound imaging system so that the ultrasound imaging system can drive the ultrasound transducer and receive return signals from the ultrasound transducer,   wherein the distal end has an outer diameter of less than about 7.5 mm and the flexible shaft has an outer diameter of less than about 7.5 mm, and wherein the ultrasound imaging system generates a complete transgastric short axis view of the heart of an adult patient based on the received return signals.   
     
     
         13 . The system of  claim 12 , wherein the shaft has an outer diameter of less than about 6 mm and the distal end has an outer diameter of less than about 6 mm. 
     
     
         14 . The system of  claim 13 , wherein the transducer is transversely oriented. 
     
     
         15 . The system of  claim 12 , wherein the distal end has an outer diameter of about 5 mm. 
     
     
         16 . The system of  claim 15 , wherein the transducer is transversely oriented. 
     
     
         17 . The system of  claim 12 , wherein the shaft has an outer diameter of less than about 6 mm and the distal end has an outer diameter of less than about 6 mm, wherein the transducer is a transversely oriented phased-array transducer with a size in the elevation direction of at least about 6 mm, and wherein the ratio of the elevation size of the transducer to the azimuthal size of the transducer is at least about 1.5:1. 
     
     
         18 . A system for transesophogeal ultrasound imaging of a heart of a patient comprising:
 an ultrasound imaging system; and   a probe including (a) a housing having a distal end and a flexible shaft, (b) an ultrasound transducer mounted in the distal end of the housing, and (c) an interface that operatively connects the ultrasound transducer to the ultrasound imaging system so that the ultrasound imaging system can drive the ultrasound transducer and receive return signals from the ultrasound transducer,   wherein the distal end has an outer diameter of about 4 mm or less and the flexible shaft has an outer diameter of about 4 mm or less, and wherein the ultrasound imaging system generates a complete transgastric short axis view of the heart of a pediatric patient based on the received return signals.   
     
     
         19 . The system of  claim 18 , wherein the shaft has an outer diameter of between about 2.5 and 4 mm and the distal end has an outer diameter of between about 2.5 and 4 mm. 
     
     
         20 . The system of  claim 19 , wherein the transducer is transversely oriented. 
     
     
         21 . The system of  claim 18 , wherein the shaft has an outer diameter of between about 2.5 and 4 mm and the distal end has an outer diameter of between about 2.5 and 4 mm, wherein the transducer is a transversely oriented phased-array transducer with a size in the elevation direction of at least about 3 mm, and wherein the ratio of the elevation size of the transducer to the azimuthal size of the transducer is at least about 1.5:1.