MIQ is a lightweight macOS QuickLook preview extension for medical volume images stored in common research formats. Press Space on a supported file in Finder to instantly see an orthogonal slice view alongside a metadata panel:
Inspired by the old, deprecated DTI-TK Quick Look plugin by Gary Hui Zhang, which offered similar functionality on older macOS versions but is incompatible with current macOS Quick Look extension architecture.
- ✅ NIfTI-1 & NIfTI-2 —
.nii,.nii.gz - ✅ FreeSurfer —
.mgh,.mgz,.mgh.gz - ✅ MRtrix —
.mif,.mif.gz - ✳️ NRRD —
.nrrd(experimental, and only the single file variant with attached header)
All formats are supported uncompressed and gzip-compressed. The extension relies on the file extension to determine the format, so it is important that files have the correct extensions.
The app and extension can be installed manually or via the package manager Homebrew.
The app is universal for Apple Silicon (arm64) and Intel (x86_64) Macs and has been tested on Apple Silicon with macOS 14 (Sonoma), 15 (Sequoia), and 26 (Tahoe).
- 👉 Download the latest release (MIQ.app.zip)
- Unzip and move
MIQ.appto your/Applicationsfolder. - Open
MIQ.appat least once to register the Quick Look preview extension. - Press Space on any supported file in Finder.
- Optional: Configure the preview settings in the MIQ app.
The MIQ main app has an update checker, which will alert you in case a new version is available. Make sure to open the main app from time to time to check for updates. The app downloads the latest version, but you will need to manually replace the old version in your /Applications folder with the new one.
- Install on the command line:
brew tap marcoduering/miq
brew install --cask miq- Open
MIQ.app(in/Applications) at least once to register the Quick Look preview extension. - Press Space on any supported file in Finder.
- Optional: Configure the preview settings in the MIQ app.
brew upgrade --cask miqMIQ is a lightweight convenience tool for quickly inspecting medical image files directly from the Finder. It prioritizes speed and ease of use over advanced visualization, and is not meant to replace dedicated medical image viewers.
Use the settings (main app) to tailor the preview to your needs. You can adjust the render orientation (see explanation below), intensity scaling, label colors and the metadata panel (content and order of the items).
By default, MIQ displays data as stored on disk, without reorienting. Depending on acquisition and processing, images may appear upside down, mirrored, or rotated. This is intentional, so you can quickly inspect the raw data including its orientation. If desired, there are settings to reorient to Neurological view or Radiological view. In both reoriented conventions, sagittal displays patient anterior on the viewer's left. Please note that for multi-volume (4D) data, only the first volume is shown.
The preview starts by displaying center slices. You can change slice positions by clicking on an image slice, dragging with the mouse or scrolling. A crosshair will appear once you start changing the slice positions. With the right mouse button (click and drag), you can adjust the intensity scaling (window/level) of the image.
Previews are designed to appear almost instantly. Uncompressed files (.nii, .mgh, .mif) are memory-mapped and impose essentially no load time regardless of size. Compressed files (.nii.gz, .mgz, .mif.gz) require decompression before rendering and very large compressed volumes may take a few seconds to load.
macOS assigns Quick Look extensions to file types based on their extensions. Since .gz is a generic extension shared by many file types, MIQ must claim it broadly to handle .nii.gz and .mif.gz files. This can interfere with other Quick Look extensions that also manage .gz files (for example, extensions for compressed archives or source code).
The most recently installed extension should have priority, but this does not work consistently. You might need to deactivate another extension to reliably open gzip-compressed files with MIQ. This is a known limitation of how macOS Quick Look handles compound extensions like .nii.gz.
The extension is still in development. It was created with the support of AI coding agents. Please report any issues or feature suggestions using GitHub Issues. If you would like to contribute, see CONTRIBUTING.md or feel free to reach out.
MIQ is provided "as is" under MIT License, without warranty of any kind, express or implied. The authors and contributors accept no liability whatsoever for any direct, indirect, incidental, special, or consequential damages arising from the use or inability to use this software, including but not limited to data loss, incorrect image rendering, or any decisions made on the basis of previews generated by this tool.
Caution
This software is not a medical device and is not intended for diagnostic use. It is a developer and researcher convenience tool only. Do not use it to make clinical decisions.