How to fix the dimensions of the voxel to be isotopic?

I recreate the three planes out of dicom images. Sagittal and Coronal planes, come distorted. A thin rectangular plane. I want to make the bigger, to expand them somehow. I have heard that I need to interpolate between slices and have them isotropic. Any ideas?

[Walter Roberson]

Do the headers of your dicom images include Z coordinates?

[Stelios Fanourakis]

My dicom images are 3d x,y,z