Thanks very much Manish. Let me follow the link you have suggested.

Hi Baraka,

I can suggest the following links. 

http://www.aylward.org/notes/open-access-medical-image-repositories

http://www.bidmc.org/Research/Departments/Radiology/NMDownload.aspx

http://www.osirix-viewer.com/datasets/

http://interactive.snm.org/index.cfm?PageID=3625&diagnostic_ctpetct=1&CFID=46445222&CFTOKEN=75998149

http://www.ibfm.cnr.it/mcet/The_database/the_database.html#DownloadDb

Hello Dear

The link is

http://www.cancerimagingarchive.net/

Thanks

dear Baraka

there two useful datasets that can help you on your way. these link are as follow :

http://www.via.cornell.edu/databases/

http://www.osirix-viewer.com/datasets/

I hope that be useful.

Regards

Thanks all for the links, they are indeed very useful for many tasks. I am continuing to learn contents of the links, but as I am dealing with fusion of images, I wanted a link that provides images of the same patient, taken from the same organ, and using two or three modalities separately. For example, assume the organ being imaged is brain of patient Y, then I need altogether two or three images: one for MRI, another for CT, and remaining for PET, for instance. In the provided links, however, I still haven't seen this.

Thank you all for nice links and contributions. I have tried most links and I am getting some useful samples, though not exactly with regard to my original problem. My interest was to have PET and CT images of the same organ from the same individual. For example, if I have a brain PET image of individual X, I should as well have a CT image of X. In that, fusion will be meaningful. Alternatively, combination of other modalities is just okay. For instance, MRI-PET or MRI-PET-CT.

You can view my CT and MRI scans w/ and w/out contrast @ http://www.pversusnp.com/

You could download PET-CT image pairs of the same organ and patient from https://www.med.harvard.edu/aanlib/