Pixels need a physical scale
Pixel spacing describes the distance between neighbouring pixel centres. Row and column spacing can differ. Image dimensions alone therefore do not tell you the physical size of an object.
Position and orientation work together
In DICOM, image position and image orientation describe how a plane is placed in the patient coordinate system. A stack should not be interpreted from filenames alone.
Thickness is not the same as separation
DICOM distinguishes nominal slice thickness from spacing between slice centres. Do not treat those values as interchangeable when checking how a volume was constructed.
Check the handoff
Before comparing two representations, confirm that they use the same scale and coordinate convention. Keep the original metadata and test with a clearly asymmetric object so an axis reversal is easier to spot.
A useful learning exercise
Imagine a rectangular object represented with different distances between samples on each axis. Write down the expected physical dimensions, then compare them with the reconstructed model. Use synthetic data for the exercise and record any transformations.