Patients in Guwahati often arrive at the centre asking why their doctor wrote MRI when their neighbour got a CT scan for what sounds like the same problem. These two tests look similar from outside (you lie on a table that moves into a tunnel) but the technology and the strengths are very different.
What is a CT scan
A CT scan uses X-rays to create cross-sectional images of the body. It is fast, taking only a few minutes, and works very well for bleeding, fractures, lung problems, and abdominal emergencies. The radiation dose is small but not zero, and CT contrast is iodine-based.
What is an MRI scan
MRI uses a strong magnetic field and radio waves to create images. There is no radiation. The scan takes longer, between 20 and 90 minutes depending on the body part. MRI is the gold standard for soft tissue, including brain, spinal cord, ligaments, cartilage, and many tumours. MRI contrast is gadolinium-based, completely different from CT contrast.
When CT is the right choice
Acute head injury, suspected lung problem, suspected kidney stone, abdominal emergencies, suspected aortic dissection, and bone fractures are usually CT studies. If you have just arrived at an emergency department with a road accident injury, CT is faster and more practical.
When MRI is the right choice
MRI is preferred for: chronic headaches, suspected stroke that is not an emergency, multiple sclerosis, brain tumours, all spine problems including disc herniation, joint injuries, ligament tears, soft tissue masses, prostate evaluation, breast cancer staging, and most paediatric brain studies. If your doctor wants to look at "soft tissue" in detail, MRI is almost always the answer.
Cost and access in Guwahati
A standard CT scan in Guwahati costs ₹2,500 to ₹5,000. An MRI is more expensive at ₹3,800 to ₹7,500 for routine studies. Both are widely available across the city, with most centres offering same-day or next-day slots.
Can you switch one for the other
No. Even though the prescription paper looks similar, MRI and CT answer different questions. If your doctor wrote MRI, do the MRI. If you cannot afford it, talk to your doctor about alternatives instead of substituting on your own.
Radiation: how much should you worry
A single CT scan delivers a small amount of radiation that is safe for almost all adults. Repeated CTs over the years add up. For young patients, pregnant women, and those who need repeated imaging, MRI is preferred when it gives the same diagnostic answer.