How dicomCollection sorts dicom filenames?

Hi,

I'm having issues when using dicomCollection to read multi-slice dicom volumes.

I'm basically following steps in this link. But here's my situation:

When loading regular dicom images (the ones I haven't processed), dicomCollection sorts the image slices correctly.

But when I try to load dicom images I created (sub-sampled MR images), it sorts like crazy, with no apparently intuitive ordering.

collection = dicomCollection(MyMRfolder, 'IncludeSubfolders', true);

for idx = 1 : numel(collection.Row)
    dicomFilename = collection.Filenames{idx};
end

FYI: there are numbers in my dicom filenames suggesting its order, as image1.dcm, image2.dcm and so on. It happens to the 'untouched' dicom images as well.

How would it sort, if dicom headers such as InstanceNumber were correctly written using dicomwrite?

Thanks

Answer 1

[drummer]

I just used sort to fix the problem

for idx = 1 : numel(collection.Row)
    dicomFilename = sort(collection.Filenames{idx});
    collection.Filenames{idx} = sort(collection.Filenames{idx});
end

That will correctly sort the files so dicomreadVolume can read it and build the volume correctly.

[Julianna Mather]

Just be aware, files aren't always stored with filenames that sort correctly. (It's actually pretty common for them not to be.) The only way to get it right is to inspect the position metadata inside the file.

Consider using dicomreadVolume, which takes care of this for you.

[drummer]

Hi Jeff, indeed you're right. I've never seen such situation, but it certainly can occur.

Thanks for the tips using dicomReadVolume.