
X-rays are 2 dimensional, which is why complex cases require multiple x-rays
CT Scan
CT Scan is made from x-rays. Regular x-rays sends 1 beam. CT scanner sends many beams in an arc around the body. Unlike regular x-ray, it can show different level of tissue densities. In regular x-ray, bones appear white, air appears black and tissues appear grey.
What is CT Scan Slice Number? It chiefly tells you the amount of time it takes to complete the scan. CT slice count 64 takes less time to do a scan than CT slice count 16

OK. It is faster but does a higher slice count number give higher resolution? Yes and No. No, because CT slice count number is not related to resolution.

Yes, although breathings slow when your pet is under anesthesia, breathing means moving body tissues. A faster scan time can minimize the impact of body movement from breathing, giving a better image
MRI Scans
MRI does not use x-rays. It creates images by exposing hydrogen atoms within your pet's body to a magnetic field.
As tissues respond differently to the magnetic field alternations, a computer is able to convert the data into an image

Tesla is the unit of measurement to define magnetic flux density. Higher tesla number gives better resolution
So does that mean a higher MRI tesla number or a higher CT scan slice count give better diagnostic results?

Not necessarily. Most important are the expertise of radiologists, imaging technicians and the veterinary anesthesiologists.
CT Scan - Common Uses
Preparation / Assessment before complex surgery
e.g. operations for flat nosed breeds
Complex bone fractures
Investigate tumors, internal bleeding and injuries
MRI Scan - Common Uses
MRI is very good at examining soft tissues such as tendons and ligaments, evaluating spinal cord and the brain. Sometimes, your vet may suggest using both CT and MRI together
Source: Vet Shawn Han