MRI (Magnetic Resonance Imaging) uses a powerful magnetic field and radio waves — no ionizing radiation — to generate detailed cross-sectional images. The scanner excites hydrogen atoms in body tissue and measures how they relax, producing signal that a computer maps into images with exceptional contrast between different soft tissue types. Multiple pulse sequences can highlight different tissue properties, making MRI a versatile problem-solving tool rather than a single-purpose study.

CT (Computed Tomography) rotates an X-ray tube around the patient, taking hundreds of images from different angles and reconstructing them into detailed cross-sectional slices and three-dimensional volumes. Modern multi-detector systems complete a chest or abdominal scan in seconds, generating data that can be viewed in any plane or rendered as 3D reconstructions.

PET/CT combines two technologies: PET (Positron Emission Tomography), which maps metabolic activity by tracking a radioactive tracer — usually FDG (fluorodeoxyglucose, a glucose analogue) — and CT, which provides the anatomic framework. The result is a fusion image showing both where lesions are and how metabolically active they are. Cancer cells typically consume glucose at a higher rate than normal tissue, making FDG-avid lesions visible before they are large enough to detect structurally.

Ultrasound uses high-frequency sound waves to generate real-time images. A transducer pressed against the skin emits sound pulses and records the echoes bouncing back from tissue boundaries. Different tissues (fluid, fat, muscle, fibrous tissue) reflect sound differently, making ultrasound excellent at distinguishing solid from cystic structures and evaluating blood flow with Doppler — with no radiation of any kind.

Nuclear medicine studies involve injecting or inhaling a radioactive tracer (radiopharmaceutical) that travels to specific tissues based on its biochemical properties. A gamma camera detects the radiation emitted by the tracer and generates images showing organ function and physiology — not just anatomy. SPECT adds tomographic reconstruction for improved localisation, and SPECT/CT fuses function with anatomic CT detail.

DEXA (Dual-Energy X-ray Absorptiometry) uses two low-energy X-ray beams at different energy levels to calculate bone mineral density (BMD). By measuring differential absorption in bone versus soft tissue, the scanner produces a precise BMD value at the lumbar spine and proximal femur — the standard measurement sites for osteoporosis diagnosis.

Mammography uses low-dose X-rays to image breast tissue, compressing the breast to improve image quality and reduce radiation dose. Digital mammography captures images electronically. 3D mammography (digital breast tomosynthesis, DBT) acquires images from multiple angles and reconstructs cross-sectional slices — significantly improving cancer detection in dense breast tissue by reducing the tissue overlap that conceals findings on 2D imaging.