A computer-aided telecommunication system and method which employs an on-line website to allow those skilled and unskilled in computer operation to communicate with others and conduct diverse financial transactions at any time and from any computer. Subscribers and others can conduct real-time visual communication with remotely located parties, exchange still and moving images, and distribute written information at a cost that is low when compared to alternative forms of communication. The system comprises a minimum of two control stations, one privacy booth and one e-mail station adjacent to each control station, and many remote e-mail/ATM stations placed in secure monitored locations. Each subscriber is assigned a unique access code and e-mail address, and undergoes identity confirmation procedures prior to system use. For ease of e-mail communication, subscribers would only need the name of an intended recipient subscriber or subscriber group identification and not individual e-mail addresses.

1. Field of Invention
This invention relates to telecommunication and money transfer systems, specifically to a computer-aided system and method which employs an on-line website and a plurality of computers to create a subscriber network for use by skilled and unskilled computer operators alike from any computer or computer device anywhere and at any time, including personal computers in the home and office, hand-held personal digital assistants, and mobile phones, as well as any other device adapted to permit on-line access. The majority of users would be subscribers, although non-subscribers would have a more limited selection of services available on a unit cost basis. The present invention offers those unskilled in computer operation, as well as those who do not have a convenient means immediately available for computer or on-line access, the opportunity to transfer written information, images, and money to remote subscribers and others, including the transfer of notices about events, sales, and employment opportunities directed to more than one recipient; the conduct of real-time visual communication with one another; secure money transfer between individuals; make purchases, and also optionally receive still and/or moving images of remote correspondents at a cost that is relatively low when compared to alternative forms of communication. In addition those skilled in computer operation can optionally access the established subscriber network from any personal computer or other digital device permitting on-line access, a privacy booth, one of the network control stations, a network-connected local e-mail station, or one of many network-connected remote e-mail/ATM stations, to accomplish a wide variety of communication and financial transactions, including but not limited to sending money to remote individuals, paying bills, cashing checks, issuing paychecks, exchanging currencies, purchasing pre-paid telephone cards, purchasing pre-paid debit cards, purchasing money orders, purchasing transportation or entertainment tickets, purchasing goods and services such as groceries and gas, purchasing pre-paid software applications, purchasing bandwidth to send large files or for videoconferencing purposes, and pre-paying entertainment costs. Fast and private money transfer between one or more donating subscribers and one or more recipients remote from the donor, with on-camera money transfer confirmation, can take place in specially equipped privacy booths. The recipient does not have to be a subscriber. Money transfer can also take place between individuals whereby money is directly deposited in a bank or credit union account of another, or the money is made available for pick up, all or part thereof, via any remote e-mail/ATM station, control station, or local e-mail station also having ATM capability. At the option of the recipient, money pick up can be in the form of cash, pre-paid phone cards, prepaid debit cards, money orders, or other currency equivalent. Since personal identity confirmation is required for most transactions, personal home computer systems used for subscriber network access must have video communication equipment, such as a netcam. Stand-alone network-accessing units, such as remote e-mail-ATM stations, should each have video-recording and automated teller machine capability, and would be strategically placed in secure well-lighted locations, such as but not limited to convenience stores, grocery stores, drug stores, shopping malls, hotel lobbies, restaurants, theaters, bus stations, and airports. Certain cash transactions, such as the purchase of a pre-paid phone card or money order, could be completed by non-subscribers at stand-alone network accessing units. However, for most transactions at least the donor would be a network subscriber. As part of the application process for becoming a network subscriber, a digital photograph of the person is taken and entered into the network""s computer database, along with other identifying information about the subscriber, such as but not limited to social security number, full name, birth date, and/or full address and telephone number. Additional layers of security can also be employed as part of the application process on an as needed basis, including but not limited to the taking of one or more fingerprints and establishing voice recognition patterns. Thereafter, subscriber wanting to perform a variety of financial transactions through use of the present invention, whether positioned in front of his or her own computer, a local e-mail station with ATM capability located at one of the network offices where privacy booths are also located, or in front of a stand-alone remote e-mail/ATM station network accessing unit, can do so by simply entering a discrete password and allowing the system to take a current digital photograph, fingerprint, and/or voice pattern sample and compare it to the digital photograph and other data already on file in its computer database. If currently collected data matches that originally collected upon registration as a subscriber, then the subscriber is permitted access to the network to accomplish any service for which pre-payment has been made. If current and original data do not match, network access is denied and compliance with further network procedures must be achieved before the person requesting network access can be permitted use of network services. When money is transferred to another person, the recipient will receive a message about the transfer via e-mail, pager, voice mail, or mobile phone, whereafter the recipient can proceed to the nearest network-accessing unit having automated teller machine capability to obtain all or part of the transferred money. If only part of the money is withdrawn from the subscriber network, the remainder can be maintained within the network indefinitely until recipient chooses to withdraw it. Further, a video screen, microphone, camera, and speaker or speakers associated with an e-mail station in a network office housing privacy booths, or as part of a stand-alone remote network-accessing unit, can further assist subscribers by providing full motion video customer service and alternatively provide the network with the opportunity for revenue generation through full motion video advertising. The simplest preferred embodiment of the subscriber system comprises two central processing units; two computer monitors; four keyboards; two printers; two printer/scanner/fax/copier combination units unless separate equipment for printing, scanning, faxing, and copying is alternatively made available for use; two video recorders; at least two privacy booths in which to conduct visual conferences, each having a high resolution monitor, a live video capture camera, audio speakers, at least one microphone, an optional writing surface, and at least one piece of furniture which can comfortably seat visual correspondents; and a plurality of network-accessing units each having video-recording capability that are strategically placed in secure locations to facilitate money transfer and other financial transactions.
2. Description of Prior Art
Recent technological advances have made worldwide communication between many remotely located business associates, friends, and family members nearly instantaneous and relatively easy to accomplish. Also, for those having computer skills and inexpensive on-line computer access, the cost of such communication has been dramatically lowered. However, there are people who lack computer skills, those who travel frequently or become temporarily relocated for periods of time too short to establish or transfer local telephone service, and those who lack the ability to purchase the computer hardware and software necessary for online access, who have not been able to take advantage of this technology. These people find alternative forms of communication expensive, subject to delay, and often totally inadequate when an important letter or package is not delivered to the intended recipient in its original condition or is never delivered at all.
Non-Internet communication between people in different countries can be particularly difficult. A letter traveling to someone in a remote location can take two weeks or longer for delivery. Weak law enforcement and corruption can further complicate the process and place money transfer between friends and family members in different countries at particularly high risk. For example, newspaper articles have cited the disappearance of millions of dollars sent annually by migrant workers in the United States to their families in Mexico. U.S. Postal Service money orders are used to send approximately one-third of such funds, and during the period between 1988 and 1998 claims alone for lost and stolen U.S. Postal Service money orders increased six-fold to more than $12 million. False identification is often used to divert the funds from the intended recipient. Violent gangs, as well as corrupt money exchangers, postal workers, and police, have been found responsible for perpetuating the problem. A secure means for transferring money between remotely located friends and family members, particularly when friends and family members are located in different countries, is much needed.
The present invention brings a solution to the existing problem by offering to those who may be unskilled in computer operation, or not otherwise in a position to use computer technology, a way of accessing it so as to have instant communication with remotely located friends and family members, rapid transfer of money from one to the other, and also instant transfer of up-to-date still and/or moving images from one to the other at a cost that is relatively low when compared to alternative forms of communication. In the alternative, it can also provide a means for any subscriber through a personal computer at home or in the office, other personal digital device permitting on-line access, or remote e-mail/ATM station, to conduct a wide variety of purchases and other financial transactions. The temporary or permanent relocation of family members sometimes places a heavy burden on those affected by the separation. Having visual contact with remote loved ones during a voice communication or for a special occasion would bring added pleasure and peace of mind to both parent, grandparent, child and/or grandchild, when each can see for themselves that the person with whom they are communicating appears to be in good health. Although visual contact could be accomplished by existing methods of videoconferencing, such methods are generally too expensive to be widely used for such non-business communication and data transfer. In addition, existing videoconferencing methods have no provision for money transfer between the participants.
Other disadvantages are also inherent in the alternative prior art methods available for communication between separated family members and friends. While written communication can be one of the least expensive options, travel delays are common in getting a written message to remote recipients, one must have a continually updated street or post office box address for successful delivery which is not always possible, and written messages are time consuming to compose. Further, letter writing is not a task enjoyed by everyone. Courier services and overnight mail can be used to help to insure more rapid and secure delivery of written communications, but at a premium cost that can make such services great for businesses but unaffordable by most individuals for routine use. Telephone communication has the advantage of being immediate, however a person long separated from his family often cannot afford the luxury of frequent videoconferencing communication and even routine long distance charges may be cost prohibitive for use as often as separated family members might like to remain in contact, particularly when international telephone calls are necessary. Other forms of communication, including the sending of audio and/or videotapes to one another, short-wave radio communication, faxing, and e-mail, all require the availability of expensive electronic equipment for both the sender and recipient. Another factor to assess in the use of electronic communication equipment is the minimum skill level required for people to operate it. There are those who are technically unskilled and would not be able to effectively use the simplest devices available for use. Further, in the alternative when unskilled senders and/or recipients rely on currently available outside technical sources for faxing, short-wave radio communication, or e-mail services, the privacy of the communication may be compromised. While an increasing number of people are becoming computer literate and starting to rely on computers for a significant part of their communication needs, there are still those without adequate computer skills who cannot take advantage of this type of communication, and those for whom family separation has imposed at least a temporary financial burden which makes the purchase or lease of computer equipment for both correspondents unfeasible. At this time there is no known communication system or method that is low in cost to the user, private, immediate, and allows the transfer of up-to-date still and moving images between correspondents.
In addition, money transfer and other financial transactions between remotely located family members and friends, or for their benefit, is often needed and poses its own set of challenges. Money exchange through the mail is slow and frequently places the money at risk for loss. Inter-bank transactions can enhance transfer security, however they can be expensive and delays in money distribution are known to occur. Money can also be wired to individuals, however, delays can be encountered when codes are forgotten and misdirection of funds has been known to happen, many times through fraud. Where family members or friends are remotely situated from one another and have the need to periodically communicate, it would be useful to have a technologically sophisticated means for combining a video-conferencing type of communication with the prompt transfer of money, and to have such communication and money transfer available without requiring any of the senders or recipients to have computer expertise or purchase expensive equipment. It would also be helpful if the same system offered those with independent computer access a means for conducting a wide variety of financial transactions. No other system and method are known that functions in the same manner or provides all of the advantages of the present invention.
It is the primary object of this invention to provide a computer-aided system and method which can be used by separated family members and others, whether computer literate or not, to visually communicate with one another, transfer money from one to the other, transfer up-to-date still and moving pictures between them, and conduct a variety of financial transactions without having to purchase expensive computer and/or other electronic equipment to do so. It is also an object of this invention to provide a computer-aided communication system and method that will let a person who is not necessarily computer literate to send and receive confidential e-mail messages. A further object of this invention is to provide a computer-aided communication system and method which can provide telecommunication, money transfer, opportunity for conducting financial transactions, and transfer of up-to-date still and moving images at a cost to the user that is lower than that of prior art telecommunication systems. It is also an object of this invention to provide a computer-aided communication system and method that protects the privacy of all communications between users. It is a further object of this invention to provide a computer-aided communication system and method that is capable of automatically giving users a printed copy of all e-mail messages that are transmitted to them and allows them to confidentially send pre-written e-mail messages. It is also an object of this invention to provide a computer-aided communication system and method that allows a user to exchange information with all system subscribers if desired, such as information about items for sale, upcoming events, and available jobs, and for subscribers to screen such information in private. It is a further object of this invention to provide a computer-aided communication system and method that allows some transactions at remote e-mail/ATM stations by non-subscribers, and permits subscribers to communicate with and send money to non-subscribers.
As described herein, the present invention would provide a computer-aided system and method for telecommunication that would allow separated people who may not have sophisticated computer skills or state-of-the-art computer equipment of their own to schedule real-time long distance visual communication with one another, to conduct such communication in private, to effect prompt and secure transfer of money from one user to another, to transfer up-to-date still and moving images between users, and conduct a variety of financial transactions. Those who are not subscribers could use network-connected remote email/ATM stations to conduct a limited number of services in exchange for a prepaid transaction fee. A more diverse selection of services would be available on a prepaid basis to subscribers who have submitted personal identity-confirming information for storage within the network database and to be used for identity confirmation purposes at each subsequent occurrence of attempted network access. An on-line computer-accessed website would be provided for the communication link so that local telephone numbers can be used and long distance charges avoided, and so that other information can be exchanged between subscribers such as e-mail and information about items for sale, upcoming events, and available jobs. It is contemplated for the system to comprise a minimum of two control stations, at least one privacy booth in the vicinity of each control station, a local e-mail station with optional ATM capability in the vicinity of each control station, and a plurality of remote e-mail/ATM stations each placed in a secure monitored location, such as a restaurant, bar, or hotel lobby, to prevent theft or vandalism. Once the people desiring such communication have subscribed to the service and paid the designated subscription fee, each would be given a unique access code and assigned a unique e-mail address that would be added to a computer database of subscribers. Subscriber information would also be collected and added to the computer database, including a digital photograph of the subscriber, as well as one or more fingerprints, a sample of the subscriber""s speech patterns, and/or additional information about the subscriber when additional layers of security are desired, such as when identical twins or triplets want to simultaneously become subscribers. Thereafter, when a subscriber desires access to the network and enters a password on a personal computer, personal digital device, via a control station, through a local e-mail station, or through a remote e-mail/ATM station, a current digital photograph of the person attempting access is taken and compared to the original digital photograph stored in the computer database. In the most preferred embodiment of the present invention fingerprint scanning and voice recognition would only be required of the subscriber when photo identification is problematic. Upon successful identification of the person as a network subscriber, he or she is provided with instant access to all services for which a monthly fee has been pre-paid. Optionally, digital photographs could also be taken of non-subscribers using the subscriber network on a per transaction fee basis for limited services and maintained for a predetermined period of time after which they would be purged from the network database.
Subscribers remote from one another would be able to schedule videoconferences in advance, at regular intervals when desired. Immediately prior to the scheduled visual conferencing time, each subscriber or group of subscribers would be given an enclosed room by a local technician in which to conduct the visual communication in private, equipped at a minimum with a high resolution monitor, a live video capture camera, one or more audio speakers, at least one microphone, a writing surface, and at least one piece of furniture to comfortably seat them. A telephone and pneumatic tube could be provided when additional customer service options are desired. Computer equipment function for the visual communication would be handled by a skilled computer technician located at each network office where a subscriber intending to be a part of the visual communication. In the preferred embodiment an independent e-mail station in proximity of the privacy booths but not connected directly to it, would allow subscribers to independently access written e-mail messages or still images sent to them by another subscriber, and receive a printed copy of each such message. No technician would be required. A variety of financial transactions could also be accomplished at this type of local e-mail station, particularly when it also had ATM capability. To send an e-mail message to another subscriber, all a subscriber would have to do is type their unique password on a keypad, also type the name of the intended recipient subscriber on the keypad, and then insert the written message or picture into the scanner provided. A local or networked central processing unit would access the subscriber database, determine from the database the appropriate e-mail address of the intended recipient subscriber or subscribers, direct the scanner to scan the written message, and then send the scanned image to the named recipient subscribers"" e-mail addresses without creating a file for the image elsewhere in the computer""s memory, after which it would direct the scanner to return written message or picture to the sending subscriber. The transmittal would be prompt and the privacy of the communication would not be compromised. Should a subscriber want help in sending a private pre-written e-mail message to another subscriber, it could be given to a technician at the local control station with the names of the intended recipients and the transmitting subscriber""s unique access code. The message or picture would then be scanned unread by the technician, automatically transmitted by the computer to the e-mail addresses of the intended recipient subscriber or group of recipient subscribers without creating a computer file for the transmitted message other than at the e-mail address of the intended recipient subscribers, after which the technician would return the written message unread to the transmitting subscriber. After the recipient subscriber accesses each e-mail message, in the preferred embodiment the computer would automatically delete the message from the recipient subscriber""s e-mail address unless directed not to do so by the recipient subscriber, thus preserving the privacy of personal communications. The network subscription fee could include a predetermined number of e-mail transmittals during a pre-set period of time without additional charge, which would be monitored by the computer through the subscriber database, or in the alternative subscribers could be allowed the option of paying a set fee for each e-mail transmission. E-mail messages would be accessible by the recipient subscriber without paying a fee, any such expenses being covered by the fee paid by the transmitting subscriber. In the alternative, e-mail messages could be sent and received through remote email/ATM stations each having a scanner, a printer, a display screen, and a keypad for data entry. Upon entry of an access code and/or the payment of a fee, a written message could be scanned, automatically sent to the e-mail address of the recipient, and promptly returned to the sender without having a computer file made for the message in any other location than the email address of the intended recipient subscriber or subscribers. Sending subscribers would only need to remember and type their own access code, in addition to the name of the user. They would not be required to know the e-mail address of the recipient subscribers. To receive messages, receiving subscribers would only have to type their own unique access code on a keyboard or keypad, after which the computer would automatically direct all messages at the recipient subscriber""s e-mail address to be automatically printed for the recipient subscriber. If the e-mail address contained no messages, it is contemplated that the recipient subscriber would be given a written message so indicating the lack of messages so there would be no question in the mind of the recipient subscriber as to whether messages had been received. Also, after printing, it is contemplated for the computer to automatically delete the message unless instructed by the recipient subscriber to retain it for a short period of time. It is contemplated at a minimum for e-mail stations placed in locations remote from a control station to have scanners, keyboards, and printers for the private transfer of previously composed messages, letters, and/or pictures. Any of the e-mail stations could also comprise an automated teller machine (ATM) so that people wanting to send money during a visual communication or to pay for the transmittal of e-mail messages would have the funds available to do so. It is contemplated that remotely located e-mail/ATM stations would be placed in supervised locations, such as in other business establishments to include but not limited to restaurants, hotels, bars, convenience stores, grocery stores, drug stores, shopping malls, theaters, bus stations, and airports.
To exchange money during a website visual communication of the present invention, the two corresponding subscribers would decide on an amount to be transferred in front of two network technicians. Then within view of the camera the donating subscriber would hand the designated amount of money to a technician present at his or her user location. At the recipient subscriber""s location, the recipient""s local technician would count a sum of money identical to that given by the donating subscriber to his or her local technician and hand it to the recipient subscriber on camera, after which the recipient subscriber would sign documentation confirming his or her identity as well as receipt of the designated amount. In the alternative, a digital photograph could be taken of the donating and recipient subscribers for confirmation purposes. Depending upon the amount of money to be transferred, a technician at the recipient""s location would then on camera give the recipient the designated amount of money if it is a small sum, or in the alternative a check or other type of easily cashed voucher would be handed to the recipient on camera. Monetary exchange would be prompt and the donating subscriber would have real-time confirmation that the money transfer had been made. In the alternative, particularly if the recipient subscriber was to be transferred a large amount of cash and did not have a bank account to use in cashing the check, the recipient would have the option to choose one of several pre-selected banks through which prior arrangements had been made and that had agreed to release funds to such recipients within a short period of time after receipt of a communication from the local technician that included the recipient subscriber""s picture and an identification of the amount to be transferred to the recipient subscriber. A further money transfer alternative could involve the local and remote e-mail and e-mail/ATM stations. One procedure would involve the donor arranging money transfer by filling out a standardized money transfer form and paying a local technician the amount to be transferred, after which a copy of the form would be e-mailed to the intended recipient subscriber. A security code known only to the recipient subscriber but not included on the e-mailed copy of the form could be added to the original form by the technician for later verification. When the recipient subscriber receives the e-mailed form, he or she would take it to a local control station. After the recipient subscriber""s local technician verifies the security code through the donating subscriber""s local technician. The funds would be released to the recipient subscriber as cash, a negotiable instrument, or as a result of the recipient subscriber""s local technician sending a visual image of the recipient to a cooperating bank. Other variations in money transfer using the present invention can involve recipient notification of money transfer via e-mail, pager, voice mail, or mobile phone message, whereafter the recipient contacts the donor for the code required for money access. Should either of the visual correspondents desire a up-to-date still or moving picture of the others with whom he or she is communicating, the technician at the location of the subscriber wanting the image can activate video-recording equipment at any designated time during the visual communication and thereafter provide the image or images to the user before he or she departs the premises. A window in the privacy booth, or a signal light on the outside of the booth in view of a technician at the control station, could be used to signal the technician of the appropriate time to begin image capture. The image preservation, as well as all communication, would be accomplished through computer software programming and to insure privacy for the users, and no record of the communication except the copy given to the user as he or she concludes the video communication session would be preserved thereafter. Since it is contemplated for the visual conferencing services to be scheduled in advance, a record of people using such services would necessarily be kept prior thereto, however, it would only be kept for a limited period of time following each conference, possibly until the subscriber pays for the next subscription fee. Additional customer services could be made available to those using privacy booths through use of a connected telephone or pneumatic tube placing those in the privacy booth in direct communication with remotely located customer service personnel, such as opening an account, applying for a loan or mortgage, or paying bills. Walk-in service for visual conferencing would be possible, but not frequently requested since prior arrangements between remote subscribers would be necessary to insure that both were simultaneously present at a local control station for conduct of the conference. In the alternative, e-mail could be accessed at any time without a prior reservation and the email or control stations would maintain no paper record of the content of any e-mail transaction. The number of e-mail transmissions made by subscribers within a designated subscription period might be temporarily maintained in the subscriber database when needed for billing purposes, however even that information would be unnecessary if each e-mail transmission was paid for by the sending subscriber at the time it was sent.
Use of the e-mail stations by people more knowledgeable about computer operation can provide them with a diverse assortment of options, including the execution of many financial transactions such as but not limited to sending money to one or more other subscribers, paying bills, cashing checks, issuing paychecks, exchanging currencies, purchasing pre-paid telephone cards, purchasing pre-paid debit cards, purchasing money orders, purchasing transportation or entertainment tickets, purchasing goods and services such as groceries or gas, purchasing pre-paid software applications, purchasing bandwidth to send large files or for videoconferencing purposes, paying traffic tickets, and pre-paying entertainment costs. As part of the application process for becoming a network subscriber, a digital photograph of the person is taken and entered into the computer database of the present invention, along with other identifying information about the subscriber, such as but not limited to social security number, full name, birth date, and/or full address and telephone number. Additional layers of security can also be employed in varying combinations as part of the application process, including but not limited to the taking of one or more fingerprints and establishing voice recognition patterns. Thereafter, a subscriber wanting to perform a variety of financial transactions through use of the present invention, whether positioned in front of an e-mail station having ATM capability at one of the network offices or in front of a stand-alone remote e-mail/ATM network accessing station, could do so by simply entering a discrete password and allowing the system to take a current digital photograph, fingerprint, and/or voice pattern sample and compare it to the digital photograph and other data already on file in its computer database. When money is transferred to another network subscriber, the recipient subscriber can choose to receive a message about the transfer via e-mail, pager, voice mail, or mobile phone, whereafter the recipient subscriber can proceed to the nearest network-accessing unit having automated teller machine capability to obtain all or part of the transferred money. Further, a video screen, microphone, camera, and speaker or speakers associated with a local e-mail station in a network office, or as part of a stand-alone remote email/ATM station, can further assist subscribers by providing them with full video motion customer service and alternatively provide the subscriber network with the opportunity for revenue generation through full video motion advertising.
The description herein provides preferred embodiments of the present invention but should not be construed as limiting the scope of its telecommunication system and method. For example, variations in the size of the privacy booth and the selection of electronic equipment available therein; the type of printers used for the local and remote e-mail stations; the type of access code used by the corresponding subscribers to send and receive e-mail messages; the order in which the visual communication, e-mail, money exchange, and information exchange takes place; the type of digital means used for subscriber identification; and the type of fax, scanning, and copying equipment selected for use, other than those shown and described herein, may be incorporated into the present invention. Thus the scope of the present invention should be determined by the appended claims and their legal equivalents, rather than being limited to the examples given.

Method and system for computer-aided telecommunication and financial transactions


An expandable metallic stent has discontinuities of non-conducting material. These eliminate electrically conducting paths in the stent rings and cells. This makes the stent easier to image with magnetic resonance imaging (MRI). The non-conducting material can include adhesives, polymers, ceramics, composites, nitrides, oxides, silicides, and carbides. The discontinuity is preferably shaped so that during expansion the discontinuity is placed in primarily a compressive stress.

This invention relates to stents, such as those placed in a human body to hold open a stenosed lumen. In particular, the invention relates to metal stents that can be viewed effectively by magnetic resonance imaging (MRI).
Currently, x-ray fluoroscopy is the preferred imaging modality for cardiovascular intervention procedures, such as balloon angioplasty with stents. The visualization and tracking of stents under fluoroscopy is accomplished either by the stent""s inherent adsorption of x-rays or by the placement of radiopaque markers. At this time, no other method has the temporal or spatial resolution of fluoroscopy. Nonetheless, fluoroscopy has drawbacks for both patient and clinician. Catheterization is required in order to directly inject a high concentration of iodinated contrast agent into the coronary arteries. Systemic administration of the contrast agent is not practical, as it would require too high a dose. Furthermore, iodinated contrast agents are nephrotoxic, with a low but measurable incidence of short-term renal failure. Allergic reactivity also serves a contraindication for certain patients. Fluoroscopy also uses ionizing x-ray radiation, with its attendant hazards. This is an issue for the patient during protracted or repeat interventions. It is a also a daily issue for medical personnel, who must cope with the burden of their own dose monitoring and of wearing lead shielding.
Fluoroscopy generates a two-dimensional projection image of what are three-dimensional structures. This requires multiple views to appraise complex vasculature. Another imaging modality, which has the potential to supplant fluoroscopy and become important in the diagnostic imaging of stents, is magnetic resonance imaging (MRI). One advantage of MRI is that it is a tomographic imaging technique that generates a 3-D data set of the imaged tissue. Consequently, the data set can be manipulated to show different imaging planes and slice thicknesses. This permits high quality transverse, coronal and sagittal images to be obtained directly. MRI has greater soft tissue contrast and tissue discrimination than computed tomography (CT) or other x-ray based imaging modalities, such as angiography. As another advantage, MRI also does not use ionizing radiation and does not require catheterization to image the vasculature.
The technique of MRI encompasses the detection of certain atomic nuclei (those possessing magnetic dipole moments) utilizing magnetic fields and radio-frequency (RF) radiation. It is similar in some respects to x-ray computed tomography in providing a cross-sectional display of the body organ anatomy, only with excellent resolution of soft tissue detail. In its current use, the images constitute a distribution map of protons, and their properties, in organs and tissues. However, unlike x-ray computer tomography, MRI does not use ionizing radiation. The fundamental lack of any known hazard associated with the level of the magnetic and radio-frequency fields that are employed renders it possible to make repeated scans. Additionally, any scan plane can readily be selected, including transverse, coronal, and sagittal sections. MRI is, therefore, a safe non-invasive technique for medical imaging.
The hydrogen atom, having a nucleus consisting of a single unpaired proton, has one of the strongest magnetic dipole moments of nuclei found in biological tissues. Since hydrogen occurs in both water and lipids, it is abundant in the human body. Therefore, MRI is most commonly used to produce images based upon the distribution density of protons and/or the relaxation times of protons in organs and tissues. The majority of the signal in MRI comes from water. Tissues vary in their water content, but for angiography, blood is the relevant tissue. Blood is approximately 93% water. This translates into a proton concentration of 103 moles/liter. However, MRI can image tissues with a lower water content. For example, grey matter and bone are 71% and 12% water respectively. It must be noted that MRI can image proton concentrations much lower than those of blood or grey matter. Image resolution is determined by the signal to noise (S/N) ratio. Faster acquisition of data or longer acquisition times both increase the signal to noise ratio.
MRI is presently used for diagnostic applications, but interventional MRI is an active area of research. For devices to be seen under MRI, they must be MRI xe2x80x9ccompatible.xe2x80x9d In the context of a diagnostic or interventional procedure, this refers to the ability to accurately image a stent. MRI imaging schemes for devices are divided into two categories, active and passive. Active imaging requires some sort of electrical circuit on, or electrical connection to, the device. This presently is not an easily implemented solution for small, free-standing devices such as stents. The passive imaging scheme that applies readily to metal stents is based on the stent material""s magnetic susceptibility and electrical conductivity.
Because stents are constructed of electrically conductive materials, they suffer from a Faraday Cage effect when used with MRI""s. Generically, a Faraday Cage is a box, cage, or array of electrically conductive material intended to shield its contents from electromagnetic radiation. The effectiveness of a Faraday Cage depends on the wave length of the radiation, the size of the mesh in the cage, the conductivity of the cage material, its thickness, and other variables. Stents do act as Faraday Cages in that they screen the stent lumen from the incident RF pulses of the MRI scanner. This prevents the proton spins of water molecules in the stent lumen from being flipped or excited. Consequently, the desired signal from the stent lumen is reduced by this diminution in excitation. Furthermore, the stent Faraday Cage likely impedes the escape of whatever signal is generated in the lumen. The stent""s high magnetic susceptibility, however, perturbs the magnetic field in the vicinity of the implant. This alters the resonance condition of protons in the vicinity, thus leading to intravoxel dephasing with an attendant loss of signal. The net result with current metallic stents, most of which are stainless steel, is a signal void in the MRI images. Other metallic stents, such as those made from Nitinol, also have considerable signal loss in the stent lumen due to a combination of Faraday Cage and magnetic susceptibility effects.
At this time, MRI is being used to non-invasively image many regions of the vasculature. The comprehensive cardiac MRI exam has demonstrated clinical utility in the areas of overall cardiac function, myocardial wall motion, and myocardial perfusion. It may become the standard diagnostic tool for heart disease. With these advances in imaging technologies, a stent that can be meaningfully imaged by MRI in an optimal manner would be advantageous. A non-metallic stent obviously solves the imaging problem. Metals, however, are the preferred material as they make strong, low profile stents possible. Unfortunately, most metal stents, particularly of stainless steel, obliterate MRI images of the anatomy in their vicinity and obscure the stent lumen in the image. By reducing the amount of metal in the stent, or by making the cells larger, or by having fewer cells, the Faraday Cage effect may be reduced. The RF radiation used in MRI has a wavelength of 2 to 35 meters depending on the scanner and environment of the stent. Therefore, the cell sizes of stents are already much smaller than the RF wavelength. Increasing the stent cell size would work only primarily by decreasing the amount of metal. This solution is limited by the need for stents to have adequate radial strength and scaffolding.
Stents commonly have some form of ring elements. These are the portions of the stent that both expand and provide the radial strength. These ring elements are joined by links of various sorts. This combination of rings and links creates enclosed cells, and taken together, they create many continuous loops of metal. These loops can run around the circumference of the stent, or they can run in portions of the sent wall. Examination of any modern stent pattern will show a variety of hoops, rings, loops, or cells that provide many electrically conductive paths. It is this structure that creates a Faraday Cage, and its associated problems with MRI. Examples of such structures can be found in the Handbook of Coronary Stents, edited by Serruys and Kutryk. Another such stent is disclosed in U.S. patent application Ser. No. 09/753,232 to Hong and Limon, filed Dec. 28, 2000, and assigned to Advanced Cardiovascular Systems, Inc. (ACS), the assignee of the present application. In that application, the inventors disclose a hybrid stent with metal rings and polymer connecting links. The polymer links prevent current flow between rings, but the rings themselves represent complete potential current paths that still impede meaningful imaging through MRI.
In the United States, the most popular stent configurations appear in the: 1) MultiLink(copyright) family developed by ACS, which is now selling later developed models like the Tetra(copyright); 2) the NIR(copyright) stent, sold in the United States by Boston Scientific Corp. and SciMed Life Systems, Inc.; 3) the MicroStent(copyright) family developed by Medtronic AVE, including the latest generation of stents, the xe2x80x9cSxe2x80x9d series; and, 4) the BX Velocityg by Cordis Corp., successor to a variety of stents including the PalmazSchatz, Crown, and MiniCrown models. A challenge is how to break up a stent pattern""s many conductive paths that form a Faraday Cage, thus permitting a clear MRI image of the stent lumen while still maintaining the strength and mechanical function of the stent. Stents which can be imaged, non-invasively, by MRI for both their lumen and surrounding tissues will have greater clinical utility than those which cannot. Such clinical utility often translate into commercial success. This is particularly true if the device allows a non-invasive procedure versus an invasive one. Once patients become aware of a non-invasive alternative, they tend to demand it.
To eliminate or reduce the Faraday Cage effect, one approach is to break up the continuous, metallic, electrically conductive paths in the stent pattern.
The present invention is a generally cylindrical metal tube. The tube has apertures, so that the stent comprises electrically conductive cells and circumferential rings. The metal tube also comprises a plurality of electrical discontinuities that include an electrically non-conducting material. The electrically non-conducting material can be a polymer or an adhesive. It can also be a ceramic or a composite material.
In one embodiment, the electrical discontinuities are in circumferential rings. In another embodiment, the electrical discontinuities can be in cells that are formed in the metal tube. In yet another embodiment, the discontinuities are in both the rings and cells.
The stent is formed from a tube by laser cutting the pattern of cylindrical rings in the tube. The stent also may be formed by laser cutting a flat metal sheet in the pattern of the cylindrical rings and links, and then rolling the pattern into the shape of the tubular stent and providing a longitudinal weld to form the stent. In either case, the preferred method would be to then cut the stents to form the discontinuities. Another alternative is to weld rings together. Electrical discontinuities can be placed in the rings before or after welding.