Source: https://openmyscan.com/en/guides/difference-between-mri-and-ct-scan Guide G–13 · Understanding # MRI vs CT scan — difference explained for patients MRI and CT both produce cross-sectional pictures, but the machines work differently, feel different in the room, and shine in different clinical situations. Neither modality is "stronger" in every case. Your team picks based on the question they need answered. However you acquired the scan, the files on your disc are probably DICOM either way. Gabriel Theis Founder, OpenMyScan 4 min read Updated October 26, 2026 Intermediate ## What's the difference between MRI and CT? MRI and CT scans can both produce DICOM images, but they work differently: MRI uses magnetic fields and radio waves; CT uses X-rays. Which examination is appropriate depends on the clinical question and individual circumstances. Drop either into openmyscan.com to view the slices. Open your scan free at openmyscan.com. 1. MRI uses magnetic fields and radio waves. There is no ionizing radiation, and exams take longer with loud knocking. 2. CT uses rotating X-rays to produce cross-sectional images and involves ionizing radiation. 3. Both export DICOM folders you can open the same way in OpenMyScan once you copy them locally. ## Step 1 — MRI in patient terms MRI uses magnetic fields and radio waves to produce images. Its images may include several sequences, each with a different appearance. Examination preparation and screening are handled by the imaging team. Once you have the disc, our free [MRI viewer](https://openmyscan.com/en/mri-viewer) opens the sequence list (T1, T2, FLAIR, DWI) in the browser. ## Step 2 — CT in patient terms A ring-shaped gantry contains an X-ray tube and detectors. A computer reconstructs the measurements into cross-sectional images. Our free [CT viewer](https://openmyscan.com/en/ct-viewer) opens the same DICOM folder with adjustable window/level for lung, bone, and soft-tissue views. ## Step 3 — Why your doctor picked one The choice depends on the clinical question and individual circumstances. The ordering clinician can explain why a particular examination was requested and how it relates to any earlier imaging. ## Step 4 — "Which is better?" There is no single comparison that selects an examination for every person or clinical question. The ordering clinician can explain the choice in an individual case. OpenMyScan displays existing image files; it does not select examinations. ## Step 5 — Opening both in OpenMyScan Copy each study into its own folder, drag them in separately, and use the sidebar to hop between series. CT window presets differ from MRI. If an image looks extreme, reset windowing before assuming something broke. ## What goes wrong after the scan? **I received both MRI and CT discs** Label folders by date and modality so you do not merge them accidentally. **The report mentions "artifact"** That usually means imaging noise, not automatically a finding in your body. **I'm anxious about radiation from CT** Ask your team for numbers in context; they balance dose against what the scan adds for your care. **MRI was cancelled because of my implant** The imaging team handles implant screening and can explain which device information it requires. OpenMyScan views existing files and cannot assess implant compatibility. // open your scan Ready Open your scan right now OpenMyScan runs in your browser. Your files stay on your computer while you review them. [Open viewer](https://openmyscan.com/en/dicom-viewer) ## Common questions ### Do I need contrast for my scan? That is a question for the ordering clinician or imaging team. OpenMyScan displays existing files and cannot decide whether contrast is appropriate. ### Is a CT dangerous because of radiation? CT uses ionizing radiation. This file-viewing guide cannot assess the risks or benefits of an examination; the imaging team can explain the exposure and the reason for your scan. ### Which is louder? MRI. CT is mostly quiet aside from motion instructions. ### Does this work offline? You can continue viewing an already loaded study while its tab stays open. Load the intended study and try the features you need while online first: an uncached decoder or feature may still require a connection. Loading the page once does not guarantee full offline use after reopening it. → try it now ## Open *your* scan Your original scan files are read on your device without a scan upload. Local previews and settings can persist after closing the tab; clear this site’s browser data to remove them completely. [Open viewer](https://openmyscan.com/en/dicom-viewer) [Browse all guides](https://openmyscan.com/en/guides) ## Keep reading [All 14 guides →](https://openmyscan.com/en/guides) [G–12 · Understanding What is a DICOM file? DICOM is the file format every MRI and CT scanner produces. It is not a photo. A DICOM image file may hold one image or multiple frames with metadata. Here's the short version. Read guide](https://openmyscan.com/en/guides/what-is-dicom-format) [G–14 · Understanding Understanding your MRI report Your radiology report is full of words like 'hyperintense' and 'no acute pathology'. Here's what the common phrases mean in plain English. Read guide](https://openmyscan.com/en/guides/understanding-your-mri-report) OpenMyScan is a viewer for images you already own. It is not a diagnostic tool, is not FDA- or CE-cleared, and does not replace professional medical advice. Always consult your doctor.