[54] IMPLANTABLE DEVICES HAVING
ULTRASONIC ECHOGRAPHIC SIGNATURE
[75] Inventor: Martin Masters, Santa Barbara, Calif.
[73] Assignee: McGhan Medical Corporation, Santa Barbara, Calif.
[21] Appl. No.: 797,115
[22] Filed: Nov. 19,1991
[51] Int.C1.5 A61M5/00
[52] U.S. CI 604/175; 128/662.03
[58] Field of Search 604/175, 93;
128/660.07, 662.03, 915, 916
[56] References Cited
U.S. PATENT DOCUMENTS
3,919,724 11/1975 Sanders et al 604/175
4,341,120 7/1982 Anderson 128/916
4,633,883 1/1987 Matsui 128/660.07
4,697,595 10/1987 Breyer et al 128/660.07
4,710,174 12/1987 Moden et al 604/175
4,760,837 8/1988 Petit 604/175
4,781,680 11/1988 Redmond et al 604/93
4,781,685 11/1988 Lehmann et al 604/175
4,785,818 11/1988 Hardin 128/660.07
4,861,341 8/1989 Woodburn 604/175
[ii] Patent Number: 5,201,715 [45] Date of Patent: Apr. 13,1993
4,862,892 9/1989 Green 128/660.07
4,932,414 6/1990 Coleman et al 128/662.03
5,042,493 8/1991 Saito et al 128/662.03
Primary Examiner—Paul J. Hirsch
Attorney, Agent, or Firm—Michael G. Petit
[57] ABSTRACT
A target having a characteristic ultrasonic signature for implantation beneath the skin is described. The target, when placed within an implanted injection port enables ultrasonic echographic discrimination of the target from surrounding tissue. In particular, the target enables one to locate its position beneath the skin non-invasively by means of ultrasonic echograpy. In practice, the signature comprises reflections of ultrasonic waves from a target comprising varying thicknesses of a material having sound transmission characteristics different from human tissue. Ultrasonic sound waves reflected from different surfaces of the target arrive at a detector with a characteristic time delay thereby providing a signature. Biocompatible plastics, such as methacrylate, polysulfone, polytetrafluoroethylene or polyethylene, or elastomers such as silicone may be used for the target.
5 Claims, 4 Drawing Sheets
