Cross-sectional anatomy

The three planes

Every cross-sectional study is built from three orthogonal planes. The axial (transverse) plane cuts the body top-to-bottom into slices and is the workhorse of CT. The coronal plane divides front from back; the sagittal plane divides left from right. Learning to picture a structure across all three planes is the core skill of radiological anatomy.

CT vs MRI

CT and MRI both produce cross-sectional images but show tissue differently. CT is fast and excels at bone, lung and acute bleeding, with contrast highlighting vessels and organs. MRI gives superior soft-tissue detail across many sequences (T1, T2, FLAIR, diffusion), which is why brain, spine, joint and pelvic anatomy are usually learned on MRI. The same structure looks different on each — recognising it either way is what practice builds.

What to learn first

Start with the landmarks that orient every study: the great vessels and heart chambers on a chest CT, the liver segments, pancreas and kidneys on an abdominal CT, and the ventricles, basal ganglia and brainstem on a brain MRI. Once the landmarks are automatic, the smaller structures fall into place around them.

Keep practising by region

Work through anatomy one modality and region at a time — brain MRI, abdominal CT, cardiac MRI and more — and let each explanation fix the structure in memory.