Explore advanced medical imaging technologies used in healthcare settings, such as MRI, CT scans, ultrasound, and PET scans. Understand the principles, applications, and maintenance requirements for each imaging modality.
Advanced Medical Imaging Technologies – Study Notes
| Modality | Principle | Key Recent Developments | Clinical Impact |
|---|---|---|---|
| Magnetic Resonance Imaging (MRI) | Nuclear magnetic resonance of hydrogen protons in a magnetic field. | • 7‑Tesla (7T) scanners – ultra‑high field for sub‑millimeter detail. • Compressed sensing & parallel imaging – faster scans, less motion artifact. • Magnetic Resonance Fingerprinting (MRF) – simultaneous multi‑parameter mapping (T1, T2, PD). • Hyperpolarized ^13C MRI – real‑time metabolic imaging. |
• Early detection of micro‑lesions (e.g., neuro‑degeneration). • Quantitative biomarkers for treatment monitoring. |
| Computed Tomography (CT) | X‑ray attenuation measured from multiple angles, reconstructed into cross‑sections. | • Photon‑counting detectors (PCD‑CT) – energy‑resolved imaging, higher contrast, lower dose. • Iterative reconstruction (IR) & AI‑enhanced reconstruction – noise reduction, dose reduction. • Dual‑energy & spectral CT – material decomposition (e.g., iodine vs calcium). |
• Precise vascular plaque characterization. • Low‑dose lung cancer screening. |
| Positron Emission Tomography (PET) | Detection of 511 keV photons from positron‑electron annihilation; maps radiotracer distribution. | • Total‑body PET (≈2 m axial FOV) – whole‑body imaging in a single scan, ultra‑low dose. • Novel tracers – ^68Ga‑PSMA (prostate), ^18F‑flortaucipir (tau), ^18F‑FDG analogs for inflammation. • Hybrid PET/MRI – combined functional and high‑soft‑tissue contrast. |
• Early systemic disease staging. • Theranostics (diagnostic + targeted radionuclide therapy). |
| Ultrasound (US) | High‑frequency sound waves reflected from tissue interfaces. | • Ultra‑fast (plane‑wave) imaging – >10,000 fps, enables shear‑wave elastography & functional Doppler. • 3‑D/4‑D volumetric probes – real‑time volumetric rendering. • Contrast‑enhanced ultrasound (CEUS) – microbubble agents for perfusion assessment. |
• Point‑of‑care cardiac and abdominal evaluation. • Non‑invasive liver fibrosis staging. |
| Optical Imaging | Light‑based techniques (e.g., OCT, fluorescence, photoacoustic). | • Optical Coherence Tomography Angiography (OCTA) – microvascular mapping of retina. • Photoacoustic tomography – combines optical contrast with ultrasound resolution for deep tissue imaging. • Multiphoton microscopy – in‑vivo cellular imaging in research settings. |
• Early detection of retinal disease, skin cancer. • Real‑time guidance during surgery. |
| Hybrid & Emerging Systems | Combine complementary physics for synergistic data. | • PET/CT & PET/MRI – |