Difference Between CT Scan and MRI

It was back in 1895 when a German scientist, Wilhelm Roentgen, first used ionized radiation to take the X-ray by pointing a beam of ionized rays through a part of the body. Today, the world of radiology has seen great changes with the introduction of highly sophisticated imaging equipment. The CT and MRI scans have really revolutionized the world of radiology because both these technologies offer highly accurate images. Many people think both these technologies work in the similar way and have no different uses. The truth is that there is a subtle difference between CT scan and MRI. Keep reading to clear your confusions.

Differences Between CT Scan and MRI

Both MRI scans and CT scans provide diagnostic images of your internal organs. However, both technologies work in a very different way to accomplish great results. Here's more about the difference between CT scan and MRI:

1.  Definition

CT scan or Computed Tomography uses a combination of X-rays and computer technology to produce detailed, cross-sectional image of the body. Your doctor orders a CT scan to see the shape, size and position of structures that are deep within your body, such as tissues, organs or tumors. You should not have a CT scan performed if you're pregnant.

MRI or Magnetic Resonance Imaging is another commonly used diagnostic imaging technique used to produce cross-sectional images of your body. The difference is that it doesn't use any radiation. The MRI tool makes use of a sophisticated computer and magnetic fields to take high-resolution images of your soft tissues and bones. It is important to inform your doctor about any metal clops, implants or other metal objects you have in your body before undergoing an MRI scan.

2.  Purpose

The purpose of ordering a CT scan is to have a closer look at the soft tissues and organs in your body. It will also help diagnose an infection, and surgeons may also use CT scans to identify masses and tumors, or to reach the right area during a biopsy. CT scans also help with the study of blood vessels.

MRIs are usually ordered to diagnose any abnormalities throughout the body, such as tumors and brain aneurysms. Your doctor may order an MRI scan if he or she gets inconclusive results through other imaging scans.

3.  Time Length

It takes less time during CT scans to take diagnostic images than an MRI scan. A CT scan may take up to 5 minutes to take an image, whereas MRIs may take about half an hour on average (quick in 15 minutes and long in 2 hours) to take an image.

4.  Image Specifics

CT scans provide good details about your bony structures, and the best thing is that a CT scan can take a diagnostic image of soft tissues, bones and blood vessels at the same time. It can also provide impressive soft tissue details, especially when done using intravenous contrast. As it has a fast imaging speed, it offers images with higher resolution and reasonably less motion artifact.

MRIs are usually less detailed as compared to CT scans, but they provide more soft tissue details. MRIs are usually ordered when it is important to see subtle differences between different types of soft tissues.

5.  Radiation

CT scans involves radiation, which is usually between 2 and 10 mSv. It's the nearly the same as that you usually receive from background radiation in 3-5 years. Since the radiation can be quite strong, it is, therefore, important for pregnant women to avoid CT scans, unless it's absolutely necessary. MRIs don't involve any ionizing radiation whatsoever, which is the reason why they are a better choice in so many situations.

6.  Effects on the Body

An important difference between CT scan and MRI is related to the effects they create on the body. Since CT scans use radiation, they carry greater risks. MRIs have no biological hazards, but you may be allergic to the contrast dye, which make it not suitable for you if you have liver or kidney disorders.

7.  Comfort Level

CT scans are a lot more suitable for claustrophobics, whereas MRIs can be quite stressful due to claustrophobia. It often feels irritating and unsettling to stay still on a hard table for an extended period of time.

8.  Limitation

You cannot get MRIs if you have metal implants in your body. That's mainly because MRIs use magnetic fields. CT scans is the only choice in case you have a metal object in your body. However, you may not be able to fit into a conventional CT scanner if you're heavier than 450 lbs. Similarly, you may be over the table's weight limit in MRIs if your body weight is over 350 lbs.

9.  Cost

You will find CT scans a lot more affordable as compared to MRIs. You usually need to spend anywhere between $1,200 and $3,200 for a CT scan, but the cost may go up to $4,000 when you opt for an MRI scan.

10.  History

Sir Godfrey Hounsfield invented the very first CT scanner in the UK, which was used for a patient's brain-scan in 1971. MRI scanners became available in 1981, but have now become as popular as CT scanners.

These are some of the most common differences between CT scan and MRI. Both technologies have their advantages and disadvantages, your doctor will consider your unique circumstances before ordering any particular diagnostic imaging test. 

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