Mri equipments

this ppt is about mri equipments

1. MAAJID MOHI UD DIN MALIK LECTURER COPMS, AU BATHINDA PUNJAB Mri equipments

2. MRI machines vary in both size and shape. The older designs had a more compact and small space and were very closed. This affected the patients mentally and usually scared them even before they went in for the examination. However, the engineers have tried to solve this problem by improving the machine to be more open and inviting. They have expanded the sides and included much more space in the scanner than the original models.

3. The basic design of a Magnetic Resonance Imaging scanner is the same in almost all machines. The scanner consists of a 24 inch wide tube, inside which the examination takes place. It also contains: A magnet, Radio Frequency (RF) coil, Gradient coils P atient table, and C omputer system .

4. Magnet The magnet is the most important and biggest part of the MRI device. It is this   magnet that allows the MRI machine to produce high quality images. There is a   horizontal tube that runs through the magnet and is called a bore. The magnet   is extremely powerful and its strength is measured in either ‟teslaˮ or ‟ gaussˮ ( 1 tesla = 10 000 gauss). Most MRI magnets use a magnetic field of 0.5 to 2.0   tesla, when the Earth’s magnetic field is only 0.5 gauss. The magnetic field is   produced by passing current through multiple coils that are inside the magnet , resulting in a state of superconductivity , which produces a lot of energy by reducing the resistance in the wires to zero .

5. Gradient Coils There are  three  different gradient coils that are inside the MRI machine and are located within the main magnet. Each one of these produce three different magnetic fields that are each less strong than the main field. The gradient coils create a variable field (x, y, z) that can be increased or decreased to allow specific and different parts of the body to be scanned by altering and adjusting the main magnetic field .

6. Radio Frequency (RF) coils The basic function of the RF coils is to transmit radio frequency waves into the patient’s body. There are different coils located inside the MRI scanner to transmit waves into different body parts. If a certain area of the body is specified, then all the RF coils usually become focused on the body part being imaged to allow for a better scan.

7. Patient Table This component simply slides the patient into the MRI machine. The position at which the patient lies down on the table is determined by the part of the body that is being scanned. Once the part of the body under examination is in the exact center of the magnetic field, which is referred to as the isocentre, the scanning process is started.

8. Antenna/Computer System The antenna is a very sensitive device that easily detects the RF signals emitted by a patient’s body while undergoing examination and feeds this information into the computer system. The computer system is a powerful system, whose major function is to receive, record, and analyze the images of the patient’s body that have been scanned. It interprets the data sent in by the antenna and then , helps to produce an understandable image of the body part being examined.

9. MRI Safety S = Search for Hazards A = Analyze the Risk F = Find the Cause E = Eliminate the Cause T = Tell Others Y = You are Safe

10. MRI : Imaging Principle Pt. is placed in magnet Radio wave is sent in Radio wave is turned off Pt. emits a signal Signal is received & used for reconstruction of the picture.

11. MRI Environment MRI un it s h o u l d b e desi g n e d to restrict a c c e ss f o r unrelated persons . A number o f g u i d e li n e s all o v er t h e wor l d to rest r i c t t h e access in MRI. But all have same o b ject i ve to ensure safe MRI environment every time. One wi d ely a c c e pt e d app r o a ch is a 4 zone desi g n recommended by ACR.

12. MRI Environment

13. Safety Issues: History Used clinically since mid 1980 No known biological effects associated with B o of MRI, a no. of accidents have occurred in MRI environment. In 2001 a t r agedy occurred wh e n a 6 yr child was killed.

14. Safety Issues: History Blue Ribbon Panel of MRI Experts by ACR to produce guidelines for MRI safety. In 2oo2, “white paper” was published & intended to provide guidelines for imaging facilities for development & implementation of safety policies & procedure. Since then it has been revised, rebutted & updated periodically.

15. Safety Issues & Risk in MRI What are the safety concerns? & How can MRI be dangerous?

16. Safety Issues & Risk in MRI Static magnetic field: (Missile effect: devices, implants & projectiles) RF magnetic field: (tissue heating, & thermal injuries) The gradient magnetic field: (PNS, magneto- phosphine's & acoustic noise) MRI contrast agent

17. Static magnetic field Projectile or Missile Effect: Translational and rotational attractive forces on ferrous metallic objects Ferrous metallic objects are drawn to magnetic bore & can be easily pulled out of hands, pockets etc. This effect has caused several injuries & death

18. Examples: Projectile Effect

19. June 03, 2017, at Dr. Ram Manohar Lohia Institute of Medical Sciences in Lucknow , Uttar Pradesh, : Minister’s guard carries gun during MRI scan his pistol was pulled from his body and got stuck on the machine. According to reports, the cost for repairing machine was around Rs 40-50 lakh .

20. Potential Projectiles

21. RF magnetic field: Heating of tissue: some tissues nuclei absorb RF energy & enter higher energy state (less concern < 1T MR system ). Thermal injuries: When conducting materials (e.g. cable of surface coil, ECG lead), are placed within the RF field, current is produce in conductive loop. The concentration of el e ctri c c u rrent ca n cau s e excessive heating that causes tissue burns. T issue bur n i s th e most f r eque n tl y rep o r t e d adverse incident.

22. RF magnetic field related burn

23. RF magnetic field related burn

24. RF magnetic field related burn C l ot h co n t a ining anti - m i c r o bia l s o l utio n o r metal infused material can heat & cause burn. Medication patches & skin patches may have metallic components that can also heat & cause burns.

25. “A patient with an implanted intracranial aneurysm clip died as a result of an attempt to scan her”

26. While Preparing Pt for MRI Always Remember……………… Screen Change Explain

27. THANK YOU