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CT Scan or MRI scan – Differences, Safety and When you will need them

CT scan or MRI scan ?

What is CT scan – Uses, Procedure, Safety and When to do it

What is MRI scan – Uses, Procedure, Safety and When to do it

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CT scan – Radiation risks

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CT Scan or MRI scan – Differences, Safety and When you will need them

With increasing use of scanning to diagnose diseases accurately, every person comes across this question atleast once in their life. This article explains how CT scan and MRI scan work, what are the side effects, when you will need these scans, what is the difference between CT scan and MRI scan and also the cost to take CT or MRI scan.


CT and MRI scan- Similarities

Both CT and MRI scans can detect how organs inside your body look without even touching you. Yes, there was once a time when doctors needed to cut open patients just to know what was going on inside them. Thank God, times have changed. Sometimes, a radiologist or your doctor may request a contrast study (where they inject a medicine through your arms) in both CT and MRI scans, if they want a more accurate diagnosis (Infection vs Tumor, Benign tumor vs Malignant tumor, Spread of infection or tumor etc.,)


CT and MRI scan – Differences

A CT scan machine uses Xrays and MRI scan machine uses magnetism to scan your body. Click here for a complete description of how a CT scan works and how a MRI scan works. A CT scan may take around 1 to 5 minutes for actual scanning, while a MRI scan takes around 10 to 20 minutes of scanning time. Generally a MRI scan causes more noise than a CT machine (Better get your own earplugs or ask for cotton balls to stuff your ears). A CT scan has a smaller length gantry (that round hollow thing into which your body goes inside) than MRI, so the chances of getting claustrophobia are more in MRIs. Click here to know how to avoid clautrophobia in MRI scan.

Since CT scan emits Xrays to scan your body, there is a risk of radiation to your body. Radiation may cause cancer, and I stress MAY CAUSE cancer. There is no clear data as of now, as to how much radiation or how many CT scans can cause cancer. It is postulated that too many CT scans in a short span of years or in a young age can cause cancer without concrete proof. Click here for A detailed article on CT and Radiation risks. A MRI scan uses no radiation and magnetism does not cause any side effects. The reason why still more CT scans are taken is, benefits of diagnosing a disease with CT scans outweigh the harm caused by radiation risk.


CT scan and MRI scan – When you will need them

But the main deciding factor on whether you will need a CT or MRI scan is not the radiation risk or scanning time, its what you are suffering from and what the physician, radiologist think is a better modality to diagnose your suspected condition. Since CT and MRI use different physical ways to scan your body, the images produced by them are different and a few body parts are better depicted in only CT or MRI. Below are a few broad classifications and I want to stress that every patient and every disease is unique and your clnician, radiologist is the best deciding authority on which scan you need depending on the suspected disease.



MRI is the best modality and is more specific and sensitive than CT. A clinician may ask for a CT scan during emergency situations like stroke, head injury and when the patient cannot lie still in MRI for 10 minutes.



CT is the best modality to image lungs and mediastinum (the space between the lungs where heart, major vessels and food pipe travel). MRI is the best modality to image breasts and chest wall.



To see the arteries supplying your heart muscles and wheter there is any block in them, Cardiac CT or CT coronary angiogram are used (both are the same). Cardiac MRI can show your heart beating in real motion which a CT scan cannot do and hence used to diagnose heart muscle dysfunction and contractile function.


Kidney or ureter stones

CT is the only modality that shows the stones clearly and doesn’t miss any.


Small and large intestine

CT with oral contrast (where you have drink around 1 liter of water mixed with a medicine) is better than MRI. However a physician may ask for a MRI scan if he thinks you may need multiple time scannning.


Uterus and Ovary

MRI is far superior than CT in imaging diseases of uterus and ovaries.


Liver, Pancreas, Gall bladder, Spleen

Too many variables and diseases, entirely a physician / radiologist opinion on whether to do CT or MRI.



MRI is far superior than CT in imaging diseases in and around joints. Only when fractures are suspected and a physician requires to get a 3D view the bones to be operated, he may ask for a CT.


Arteries in neck, chest, abdomen, arms and legs

CT angiogram (with contrast)  is routinely used.  MRI Angiogram (without contrast) can be used in renal failure patients and in patients with contrast allergy.


Pregnant patients

CT is contraindicated (not adviced) due to radiation risk to the baby. MRI scan is usually used in pregnant patients to scan the mother or the baby if required.


Pus discharge or abscess  around anal region

MRI Fistulogram is routinely used. CT Fistulogram requires injection of contrast through the discharging opening and may be painful.

I stress once again, these are the general recommendations for these broad categories and each patient is unique and may be offered CT or MRI depending on their condition.


CT scan and MRI scan – Cost

The following are the prices in our Aarthi scans and labs. We are the most affordable diagnostic service provider in India and transparency is our motto.

As a routine, we charge lesser prices in night time (8PM to 12 mid night, all through the year) to help patients in need.  The charges are,

  • Cost of MRI scans is Rs 4000 per study
  • Cost of CT scans in night is Rs 1000 to 2000 per study
  • Cost of MRI scans in night is Rs 2500 per study

Note – Special studies like Angiogram, Cardiac MRI, MRI Abdomen, Fetal MRI etc are priced differently than above charges. So, to sum up.. CT – Radiation risk, lower cost, quick to image. MRI – No radiation, costlier, Imaging takes time. If you have any doubts or have anything more to add, please comment below. Spread the knowledge. Share this article in Twitter, Facebook

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