Important Considerations to Review Before Purchasing an MRI System

mri system

Before purchasing an MRI system, it is important to take into consideration the following main technical points, in order to make the best decisions possible for your medical facility:

• The MRI system should be FDA-approved
• The MRI system should comply with the IEC 60601-2-23 standard
• The MRI system should comply with all Dicom 3.0 mri working modalities
• Consider the magnetic field strength of the MRI system: 1.5T ,3T or other. (1.5T is currently the most commonly accepted MRI magnetic field strength for general use).
• Decide which bore diameter of the MRI system, 60 cm or the larger bore diameter, 70 cm is what you are looking for, keeping in mind that sometimes, the size of the useful volume of view and the image quality are lower with the larger bore diameter.

Understanding MRI Scanner Receivers

How Advanced Technologies Improve MRI Imaging

Multichannel radiofrequency and parallel imaging technologies are hardware and software implementations, respectively, aimed at improving the coverage, signal resolution and speed of MRI examinations. With multichannel RF technology, the MRI signal used to form an image is collected by an array of separate detectors, or coil elements. Each element relays signal information along a separate channel to an image reconstruction computer. Such arrays of coil elements and receivers can improve imaging coverage and the ratio of signal-to-noise in the image.

The number of elements in the array of detectors and receivers is an important factor in characterizing an MRI scanner. Parallel imaging technology uses complex software algorithms to reconstruct the signals from multiple channels in a way that can reduce imaging times and/or increase image resolution.

The Main Sources of MRI Noise

Before we examine the parameters of MRI scanner receivers, it is important to understand what the principal source of noise in MRI scanner signals is:

The magnetic resonance signal is an electromotive force induced in a coil by a rotating magnetic moment of nuclear spins. The MRI scanner signal level must be well above noise levels to produce clinically useful MRI images, and yet this signal is very weak.

Image noise originates in the patient to be imaged and is added during the processing of the signal in the receiver chain. In the receiver chain, noise may be generated in the preamplifiers and at the connection between the preamplifier and the RF receive coil. In the RF coil, which is a conductor, thermal noise is produced by the stochastic motion of free electrons. This motion is caused by ohmic losses in the RF coil itself, and by eddy current losses in the patient, which are inductively coupled to the RF coil. High conductivity of receiver coils avoids noise, whereas conduction in the patient causes noise.

Introducing MRI Parallel Imaging

How is MRI Parallel Imaging Used?

MRI parallel imaging utilizes the multiple elements of phased array coil system. Each element of the coil system is associated with a dedicated radio frequency channel (a special single-channel radio receiver) whose output is processed and combined with the outputs of the other channels (signals acquired by the other coil elements). This technology improves the signal–to-noise ratio (the signal quality) as compared to a standard MRI scanner coil system; while covering the same explored body volume.

The spatial data acquired by the array of coil elements is used for partial phase encoding, only to speed up the acquisition process.

The acceleration factors routinely employed at a magnetic field strength of 1.5 T can range from 2 to 3. At field 3T, this factor can be even higher.

How Parallel Imaging Improves MRI Scanning

Multi-channel radio frequency and parallel imaging technologies are hardware and software implementations, respectively aimed at improving the coverage signal resolution and speed of MRI scanner examinations. With multi-channel technology, the MRI scanner signal used to form an image is collected by an array of separate coil elements. Each element relays signal information along a separate channel to an image reconstruction computer. Such arrays of coil elements can improve imaging coverage and the ratio of signal-to-noise in the image. The number of elements in the array of detectors is an important factor in characterizing a parallel imaging system. Parallel imagingtechnology uses complex software algorithms to reconstruct the signals from multiple channels in an way that can reduce imaging times or increase  image resolution, in image resolution (without the corresponding increase in imaging times associated with standard MRI scanner imaging).

The Basics of Digital Radiology (DR)

What is Digital Radiology (DR)?

Digital radiology (DR) is a form of x-ray imaging, where digital x-ray sensors are used instead of traditional photographic film. Advantages of digital radiology (DR) include time efficiency, as a result of being able to do without the standard chemical processing, as well as the ability to digitally transfer and enhance images. Also, less radiation can be used to produce an image of similar contrast.

Digital radiology (DR) may represent the greatest technological advancement in medical imaging over the last decade. The use of radiographic films in x-ray imaging will become completely obsolete within a few years. An appropriate analogy that is easy to understand is the replacement of typical film cameras with digital cameras. Images can be immediately acquired, deleted, modified and subsequently sent to a network of computers.

What are the Main Benefits?

The benefits of digital radiography (DR) are enormous as it makes a radiological facility or department filmless. The referring physician can view the requested image on a desktop or a personal computer and often file a report just a few minutes after the examination was performed. The images are no longer held in a single location, but can be seen simultaneously by physicians who are many kilometers/miles apart. In addition, the patient can easily transfer the x-ray images on a compact disk or on a “disk-on-key” to take to another physician or hospital for consultation.

Are There Any Disadvantages?

Although digital radiography (DR) systems have the potential for dose reduction, experience shows that many facilities actually impart more doses to patients. The primary reason is that over-exposure goes undetected, unlike with film where the image turns dark or black. In digital imaging, in contrast, the image becomes better when there is over-exposure. Further, there is a tendency to take more images than necessary. In a study performed in several hospitals, it became obvious that the number of examinations per patient, per day increased after transition todigital radiography (DR).

Also, it is very easy to delete images before archiving, and technologists tend to repeat exposure if the positioning is wrong or if there is motion blur. Such repeats normally go unreported. As a result, digital imaging has the potential to increase the number of exposures and therefore, patient dose.

Flat-Panel Detectors

Due to the physical structure of the detector, detectors are frequently referred to as flat-panel detectors. In addition to forming part of an integrated digital radiography (DR) system, their shape allows them to be incorporated into retrofit digital bucky assemblies. There are also portable digital cassettes available, which are either sold as part of a system or can be retrofitted to an existing film/screen room.

Types of Digital Radiography (DR) Systems

Mobile radiography systems with portable digital detectors are also available. Portable detectors can be connected to the review workstation by either a wire, or have a wireless communication interface.

Many types of digital detectors will need some level of environmental control. This may be in terms of operating temperature range, rate of change of temperature and/or relative humidity.

All types of detectors may not function optimally if outside the recommended temperature range, but normally recover once the temperature has returned to normal. Certain types of digital radiography (DR) detectors may be irreparably damaged if the temperature remains too high or too low for an appreciable period.

There are main 4 types of flat panel detectors used in digital radiology ( DR):

1. Indirect conversion detectors first convert the X-ray photons to visible light photons in a scintillator, typically caesium iodide (Csl). The light photonos are in turn converted into electrical charge and read out with an amorphous silicon (a-Si) photos – detector/ thin film transistor (TFT) array bonded to the scintillator. The detector can be fixed or portable.
2. Direct conversion detectors convert X-rays directly to charge, which is then read out. Most current systems use a layer of amorphous selenium (a-Se) coupled to an active matrix for read out.
3. Charge coupled devices (CCDs) are sometimes used in digital systems for general radiography. A scintillator (Csi or a rate earth phosphor) is coupled to the CCD with a lens/mirror system. Due to the limited area of a typical CCD, a considerable degree of demagnification is required, which can have an effect on image quality.
4. Slot scanning systems use a fan beam of X-rays, which scans the area of interest in conjunction with a slot detector. The detector is typically a linear array of CCDs coupled to a Csi scintillator, although other combinations; such as a rare earth phosphor coupled to a linear array of sensors, are in use. This arrangement provides excellent rejection of scattered radiation (and therefore potential for lower doses).

The sensitivity of the detector is a measure of how efficiently the detector uses the incident X-ray photons and can be described in terms of various technical parameters, such as detective quantum efficiency (DQE). Sensitivity will depend on the technology and design of the detector and technically similar detectors from different manufactures may exhibit different sensitivities. Additionally, the sensitivity may vary with the energy of the incident X-rays.

Source: http://www.medwow.com/articles/

Tags: Digital Radiography, Digital Radiology, Rad Room, X-ray imaging

Computed Radiography (CR) in Radiology Applications

What is Computed radiography (CR)?

Computed radiography (CR) is a cost-effective solution to move from analog to digital imaging. With computed radiography (CR) the transition to digital is completed by installing computed radiography (CR) readers and replacing X-ray cassettes (which use X-ray film) with computed radiography (CR) cassettes (which use imaging plates). The imaging plates are exposed and inserted into the computed radiography (CR) reader. The computed radiography (CR) reader scans the plates, digitally displays the image on the workstation, and erases the imaging plate for reuse.

Computed radiography (CR) is a mature technology, which was developed in the middle of the twentieth century. It is currently in use in medical centers around the world. In many cases, it has replaced the process of taking X-rays on film in order to produce digital images. With these, better quality scans are possible, in shorter times, and with wider availability for study. The technology is found not only in medicine and dentistry, but in other areas, such as manufacturing for safety testing and analysis.

Traditional radiography, in use since its invention by W.C. Roentgen, in 1885, stores images on a photographic plate.Computed radiography (CR) can use existing X-ray equipment to take pictures but stores the images on a plate with phosphors that are activated and retained when the image is taken. A laser is used to scan the plate, which is converted to digital format. The results are then fed directly into a computer for interpretation. This simplifies the whole process, since no photographic development process is involved, meaning no dark rooms are necessary.

Since the early 1990s, it has become technically possible and economically feasible for digital imaging technologies to challenge film for projection radiography. This was made possible by certain prerequisite technological advances, such as high-luminance and high-resolution display monitors, combined with high-performance computer workstations which, though still costly, are now readily available. Electronic image archives that can efficiently store and retrieve the massive amounts of image data generated by projection radiography are becoming increasing cost- effective.

High-speed electronic networks with bandwidth adequate to transmit image files wherever and whenever needed are now accepted as an essential infrastructure component in health care.

Until the past few years, storage phosphor-based computed radiography (CR) has been the best alternative for acquiring digital projection radiography images. Computed radiography (CR) has the advantage of being fully compatible with existing x-ray equipment designed for film screen imaging. However, computed radiography (CR) has the disadvantage of requiring readout and processing steps that take about the same time as conventional film to obtain a diagnostically different has entered the medical imaging market, offering a new standard for digital x-ray image capture: digital radiography flat panel, solid state detectors with integrated, thin film transistor readout mechanisms.

Computed radiography (CR) and digital radiography (DR) have many similarities. Both computed radiography (CR) and digital radiography (DR) use a medium to capture x-ray energy and both produce a digital image that can be enhanced for soft copy diagnosis or further review. Both computed radiography (CR) and digital radiography (DR) can also present an image within seconds of exposure. Computed radiography (CR) generally involves the use of a cassette that houses the imaging plate, similar to traditional film screen systems, to record the image; while digital radiography (DR) typically captures the image directly onto a flat panel detector without the use of a cassette. Image processing or enhancement can be applied on digital radiography (DR) images as well as computed radiography (CR) images due to the digital format of each.

Advantages and Disadvantages of Computed Radiography (CR)

Computed radiography (CR) has its unique advantages:

• Cost-effective solution for upgrading old X-ray equipment.
• No silver-based film or chemicals are required to process films.
• Reduced film storage costs, as the images are stored digitally.
• Image brightness and contrast can be adjusted after the exposure.
• Image can be processed and enhanced at any time after the exposure.

However, computed radiography (CR) has also some distinct disadvantages:

• Manual handling of the cassette housing.
• Imaging plates are expensive and can be easily damaged.
• Inherent geometric lack of sharpness results in lower spatial resolution, as compared to film images.
• Low signal-to-noise ratio and sensitivity to scattered radiation.

Moving to Digital with Computed Radiography (CR)

Changing healthcare needs require tomorrow’s diagnostic imaging service provider to rapidly produce the highest quality images, transmit them broadly, display them in alternative ways, and computed radiography (CR) image systems are an important element in this all-digital vision.

With digital image systems, the image data sent to workstations, printers, and archives is always identical to the original.

With improved workflow and increased efficiency, the all-digital radiology department will help hospitals, imaging centers, private practices, and clinics realize the full benefits of a picture archiving and communication system (PACS)

Source: http://www.medwow.com/articles/

Tags: Computed Radiography, CR Imaging System, Digital Radiology, Radiographic System, X-ray CR Imaging System

Source: http://www.medwow.com/articles/

Mitigating Liability in Medical Device Recalls

Product recalls are nothing new; they exist in just about every industry. However in the medical device industry, 2012 saw a significant jump in recalls. According to the ExpertRECALL index, over 123 million device units were recalled alone in the first quarter of 2012.

Not surprising, there has been a noticeable increase in device failure and damage claims over the last few years. It’s interesting to note that although the number of unit recalls has increased, the amount of affected devices has not risen greatly.

Today’s market boasts many more medical devices that are smaller, less invasive and made of newer and lighter materials. New medical devices are designed to be more effective than previous technologies; with this in mind, why are there so many more product recalls? Industry professionals point the cause towards the baby boom generation. Representing the largest population segment at the age that requires life-saving medical devices, statistically baby boomers are increasing the magnitude of product recalls.

Medical device categories that are the most prone to recall are orthopedic implants and cardiac devices such as leads and pacemakers. These types of devices are subjected to the most friction and movement that can wear down materials leaving patients at risk to substance poisoning, electrocution or complications due to device failure.

It is known that products can fail and no medical device manufacturer is immune to product recalls. Companies Johnson & Johnson, St. Judes and Covidien are just a few that have been in the news over the past year for product recalls.

Health product recalls are big news. They increase public awareness of device failure and place pressure on government agencies to take action to protect the public. In the USA, the FDA is developing a device tracking system that will facilitate supply chain monitoring of some devices in order to improve recall efforts. Likewise in the UK, legislation is being drawn that will support greater product transparency and allow patients and doctors to make informed choices about medical products.

Other groups at play in recalls include patients and health insurance companies. Because of mounting costs from exponential increases in patient damage claims, health insurance companies are now holding medical device manufacturer’s financially responsible.

As a result of various groups passing on the liability hot potato to medical device manufacturers, clearly changes are necessary in order to mitigate damages. An obvious first step is the development of strong and easily deployed recall strategies to protect brands and limit risks to patients. However, it appears that medical manufacturers are facing a greater learning curve in order to work out issues from newer technologies and adopt procedures geared towards limiting product failure moving forward.

Source: http://www.medwow.com/articles/

tags : Cardiology Equipment, medical device, medical equipment, MedWOW, News,Pacemakers

Beware: Airport Security Could Damage Diabetes Insulin Devices

A warning published in the journal ‘Diabetes Technology & Therapeutics’ has diabetics and doctors concerned about the dangers of air travel with diabetic medical devices. According to the article, insulin pumps and continuous glucose monitorscould be adversely affected by airport security magnetic x-ray. This refers to x-ray machines used to scan luggage and travelers. It is unclear however whether this warning includes metal detectors; devices that also create a magnetic field.

Medical professionals already know magnetic and radiation based imaging technology like Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) interfere with the functioning of diabetes devices. However, initial findings from research conducted by Andrew Cornish and H. Peter Chase at the University of Colorado suggest that magnetic x-ray equipment used in airport security can also hinder the operation of insulin pumps and continuous glucose monitor (CGM) devices. The researchers found that magnetic x-ray can cause a malfunction in the devices’ motors.

The amount of diabetics that could be potentially affected worldwide is enormous. In 2010, company Market Research valued global markets for insulin delivery pumps and continuous glucose monitor systems at $7.4 billion and 92.2 million dollars respectively. Further, these markets are expected to steadily increase because of improved patient access to diabetes care and rising cases particularly among children.

There is no doubt that Cornish and Chase’s research raises a public global health risk that demands further exploration. Little is yet known about how magnetic x-ray affects insulin pumps and CGM. More research is necessary to better understand and develop solutions to the problem.

In the interim, patients are advised to travel with a doctor’s letter that forbids subjecting diabetes equipment to x-ray search. For further updates, contact your local Diabetes Association.

Source: http://www.medwow.com/articles/

tags : CT Scanner, imaging equipment, intensive care, medical device, medical equipment,MedWOW, MRI, News, X-ray