MAGNETIC RESONANCE-COMPATIBLE NEEDLE

Abstract: A medical needle is made of non-metallic, non-magnetic materials such that medical interventional procedures requiring needle access to people, animals or isolated tissues can be performed in a Magnetic Resonance Imaging (MRI) scanner without significant artefact or image distortion. The dimensions of the needle are adaptable to the task required.

Description: Magnetic resonance-compatible needle Magnetic Resonance Imaging (MRI) scanning is a method of imagmglfTe "" human body or other fleshy objects e.g. animals, either alive or dead. It depends on the object being placed in a large and uniform magnetic field (commonly ranging from 0.2-7.0 Tesla field strength according to the particular machine used). The image is created by disturbance of molecules of the body by radiofrequency (RF) pulses causing resonance of these molecules. After the RF pulse, the molecules realign with the magnetic field and in so doing, emit a weak RF signal of their own. This signal is detected and analysed by a computer and a signal map created of the interrogated body part such that a grayscale image is displayed. The appearance is usuaUy that of 'sHces' throught he body revealing the inner organs. It is useful in medical practise, to place needles in these inner organs in the presence of disease, both to extract tissue and fluid samples for analysis (biopsy) or to pass fluids or instruments down the needles to alter the tissue of interest in a variety of pre ¬ specified ways. The precise position of the needle tip is clearly vital for accurate diagnosis and/or therapy in this context. To use a needle in an MRI scanner, the needle must fulfil all the requirements for a medicinal needle in terms of strength and body compatibility as well as being compatible with the MRI imaging apparatus in that it must be both clearly visible when scanned as well as causing no distortion artefact to the final image. Any magnetic object will distort the magnetic field and thus the image, making accurate placement difficult. Such needles as are used currently, are made of metal alloys with high non-ferrous metal content and a low relative proportion of Iron but these still cause significant artefact especially at the needle tip-the most important part. According to the present invention, the needle is manufactured out of non-metallic materials such as carbon fibre, glass fibre, plastics or ceramics so as to cause no artefact on MRI scanning and allow non-distorted tip visualisation. In one embodiment of the invention the needle is made of fibre composite materials such as carbon or glass fibre wherein the fibres are arranged either axially, spirally, in circular fashion or in a combination of these orientations In another embodiment of the invention the needle is sterilizable by heat, chemicals and/or irradiation techniques allowing re-use of the needle. A specific embodiment of the invention is now described by way of example with reference to the accompanying drawings, in which:- ' Figure 1 shows the side view of the needle and a selection of accompanying components. Figure 2 shows the needle end-on Referring to the drawings Figures 1 and 2, the needle comprises an outer cylindrical tube 1 of carbon fibre, glass fibre, plastic or ceramic material with length and wall dimensions 5 and 6 variable according to the task required i.e.large or small needles. The needle has a connector 2 attached to its proximal end to allow the connection of omer apparatus. The needle bore 5 allows passage of fluids in eiϋier direction, the insertion of an obturator, mandril or trocar 3 , as well as the passage of implements such as optical light fibres 4 , catheters and more complex instruments such as ultrasound probes The needle and trocar assembly can be adapted to perform core biopsies of tissues as is currendy undertaken with metallic needles. The carbon fibre tubing is manufactured either by 'pultrusion' of the fibres over a mandril with the fibres arranged both axially and spirally, or wrapping preformed carbon fibre sheeting around a mandril with subsequent polishing of the surfaces. t It will of course ba understood that the present invention has been described above purely by way of example, and that modifications of detail can be made within the scope of the invention.

Claims: CLAIMS 1. A needle made of materials which are compatible for use in an MRI scanner wherein the material is non-metallic and causes no significant artefact or image distortion when visualized with an MRI scanner. 2. A needle as claimed in claim 1 wherein the material used is a fibre-composite material 3. A needle as claimed in claim 1 wherein the material used is carbon fibre 4. A needle as claimed in claim 3 wherein the carbon fibre is either of wrapped, or of axially and/or spirally pultruded manufacturing configuration. 5 .A needle as claimed in claim 1 wherein the material used is plastic or ceramic 6. A needle as claimed in any preceding claim that is a multipurpose, including aspiration biopsy, needle 7. A needle as claimed in any preceding claim that is sterilizable by heat or chemical or irradiation means such that it may be re-used. 8. A needle substantially as described herein with reference to the text and Figures 1 and 2 of the accompanying drawing

Inventors: BROOKES JOCELYN ASHER SIMON, BROOKES, JOCELYN, ASHER, SIMON
Applicants: BROOKES JOCELYN ASHER SIMON, UNIV LONDON, BROOKES, JOCELYN, ASHER, SIMON, UNIVERSITY COLLEGE LONDON
Application year: 1996
Main classification: A61B17
IPC codes: A61B5, A61B10, A61B17, A61B19, A61M25