Which MRI Centre is Best
The Corona Pandemic followed by the `Black Fungus‘ scare has resulted in many patients searching for MRI Scan centre. It is easy for people to understand that all cars cannot be of the same price. Cars have engine specifications and many more features which determine their price. So you can get a car for 2 lac rupees and the price of a car can be in excess of 1 crore also. The same is true for an MRI Machine. You can get an MRI machine for 1 Crore and another machine can cost in excess of 15 Crores. When you are going to get an MRI Scan done, you are not buying the MRI Machine so how should you be bothered about the cost of the machine. A better analogy would be hiring a taxi. You can hire a taxi for Rs. 10 per kilometer and you can hire a Rolls Royce for Rs. 100 per kilometer. Both are serving the same purpose of transporting you from one place to another. Now you can understand why some diagnostic centres are offering heavy discounts and doing an MRI scan for Rs. 2500 while others are charging Rs. 10000 and not giving any discounts. In order to understand the price difference between different centres you must spend some time to understand the intricacy of an MRI Machine. This article will also be of help to many practicing doctors who are in the habit of writing MRI Scan on 3T without knowing much about the physics of Magnetic Resonance Imaging.
The most important thing in any MRI machine is the magnet and its specifications. The results of MRI Scanning depend on the quality of the magnet and not on the type or the magnetic strength. There are two types of magnets in MRI Machines – Permanent and Superconducting. The MRI machines with permanent magnet come in strengths of 0.2 Tesla and 0.3 Tesla. The best MRI machines with permanent magnet are manufactured by Japanese companies like Hitachi. The MRI machines with permanent magnet can be bought for 1-3 Crores and have low running cost. The magnet is C-Shaped and therefore these are also known as Open MRI. People who are claustrophobic can get MRI scan done on these machines. A permanent magnet MRI machine of 0.3 Tesla from Hitachi would give very good quality images and most of the MRI studies can be done on this machine. The superconducting magnet comes in strengths of 1.5 Tesla and 3 Tesla. Tesla stands for the strength of the magnet and not the quality of the magnet. The quality of MRI images depends on the Spatial Resolution. MRI scanners which have a high gradient and higher slew rate will have better spatial resolution. Most of the 1.5 Tesla MRI scanners have gradient of 30-35 and slew rate of 120-125. However Siemens Avento magnet has a gradient of 45 and slew rate of 200. This would give better spatial resolution than many 3 Tesla MRI Scanners.
Another very important factor in any MRI scanner is the number of Radiofrequency (RF) Channels. MRI machines currently installed have 4, 8, 16 or 32 independent RF Channels. More the number of RF Channels in the machine, better would be the image quality. MRI of any body part is done by putting a coil around that body part. These coils also have receiver channels. A Knee coil can be 4, 6, 8, 12 or 16 channels. An MRI scanner which is 32 channel would not give great images if the coil used is only 4 channel. A 16 Channel MRI scanner would give excellent images when you use a 16 Channel Knee Coil or a 16 Channel Shoulder Coil.
Most of the MRI Scanners have a maximum field of view of 50 cms. This means than any organ which is longer than 50 cms cannot be scanned in one study. Spine is one of the longest organ and this is the reason that the whole spine cannot be scanned in one go. However the magnet homogeneity is not very good over 50 cm. Almost all the Magnets give good homogeneity over 30 cm scanning. This means that smaller organs like knee, wrist, ankle, shoulder should not have the problem of homogeneity. However bigger areas like chest, abdomen and spine would have issues of homogeneity over different MRI scanners.
The quality of the coils plays a very important role in the quality of MRI Scan. Most of the centres have 4-5 coils which includes Head & Neck Coil, Body Coil, Spine Coil, Small and Large Flex Coil. The number of receiver channels in the coil determine the price of each coil. To give you an idea, an 8 Channel Breast Coil can cost in the range of Rs. 20 – 25 Lacs alongwith the application software for doing Breast MRI. The breast MRI can also be done by using a Large Flex Coil but the quality of imaging would not be as good. Similarly some centres would invest in a dedicated Knee or Ankle Coil while others would use a small or large flex coil for doing the scan. When there is so much difference in the cost of the product then how can the pricing for a particular test be the same. Centres doing Breast MRI with a Dedicated Breast Coil are charging Rs. 12-15 thousand for this scan while those doing it with a large flex coil are charging Rs. 6-7 thousand for the same scan.
Sequences and Applications
MRI Scan is done in several sequences like T1 Weighted, T2 Weighted, Diffusion Weighted, FLAIR, STIR, Spin Echo, Gradient Echo. There are more than 100 such sequences. Each of these sequences take 3-4 minutes to complete. There are many centres which are doing just 2 sequences in an MRI Scan and charging low amount for the test.
You must have seen that the same MRI Scan is being offered at Rs. 2500 at some centres through many websites. Other centres would be charging Rs. 8000 – 10000 for the same scan. If you have bought a 12 year old MRI machine with 4 channels and are doing just 2 sequences for any MRI Scan then you can afford to charge such low amounts. It is for the patients to understand the finer nuances of this highly technical field. If you are a patient who is looking to get an MRI Scan done then ask for the specifications of the MRI machine like Tesla Strength, Channels, Spatial Resolution, Gradient Strength, Amplitude, Homogeneity, Coils, Sequences and Applications before comparing the price. However if you do not value your health then keep searching for the lowest price. Everything that is round and red is not an apple and not all apples are of the same price. Similarly comparing the prices of MRI or for that matter any medical service across different centres has no meaning unless you understand the subject. The image quality is one thing and the quality of reporting is something else. A machine may produce excellent images but if the radiologist who is going to prepare the report is not experienced enough then those images have no value. So also check the qualifications and experience of the radiologist before choosing the centre for your tests. If you find the task too onerous then going by the advice of your treating doctor is not a bad idea while choosing the best centre for your tests.