A shoulder CT provides detailed cross-sectional images of bones and joint structures. It identifies fractures, small bone fragments, dislocations, complex joint anatomy, bone degeneration (arthritis), bone tumors or infection, and calcifications. CT arthrography or 3D reconstructions improve assessment of cartilage, labrum and complex fractures. It is less sensitive than MRI for pure soft-tissue tears but excellent for bony detail and surgical planning.

For a left shoulder CT the patient lies supine, usually head‑first, with the left arm at the side (palm on thigh) or slightly externally rotated as instructed. The left shoulder is centered in the scanner gantry and immobilized. Axial images are acquired and reconstructed into coronal, sagittal and oblique planes aligned to the glenoid and humeral head for optimal assessment.

A shoulder CT scan typically requires about 5 to 10 minutes of actual imaging, but the whole visit usually takes 15 to 30 minutes. If intravenous contrast is needed, allow an extra 15 to 30 minutes for injection and brief observation. Preparation, positioning and paperwork can add time, so plan on up to about an hour from arrival to completion.

For shoulder pain, start with an X‑ray to check bones and arthritis. For suspected rotator cuff, labral tears, or other soft‑tissue injuries, MRI (sometimes with arthrogram for labrum) is the most informative single test. Ultrasound is a good, lower‑cost, dynamic alternative for rotator cuff problems. CT is mainly used for complex fractures or detailed bony planning before surgery.

MRI is better for soft-tissue problems (rotator cuff, labrum, tendons, cartilage) and bone‑marrow changes; it avoids radiation but takes longer and can be limited by metal implants or claustrophobia. CT is superior for detailed bone assessment, fractures, complex anatomy and preoperative 3D planning but involves radiation. Choice depends on the suspected problem: soft tissue → MRI; bony injury/fracture → CT.

A CT scan itself usually takes five to fifteen minutes. Including registration, positioning and instructions, most appointments last fifteen to thirty minutes. If contrast dye is used, extra time is needed for IV insertion, injection and short observation, making the visit thirty to sixty minutes (occasionally longer). Complex or multiphase studies may require more time; follow your radiology department’s guidance.