F186 Non-Ionising Medical Diagnosis

• Superconducting magnet: Produces the strong, uniform magnetic field • Gradient coils: Create variations in the magnetic field for spatial location of signals • RF coils: Transmit RF pulses to excite hydrogen atoms and receive signals during relaxation These components are essential for the operation and image generation of MRI machines.

• Alignment: Protons align with the magnetic field • Excitation: RF pulse flips protons out of alignment • Relaxation: Protons return to alignment, releasing signals • Detection: RF coils detect signals, and a computer constructs images

Different tissues have different relaxation times, producing varying image contrast This allows for tissue differentiation based on how quickly hydrogen protons return to alignment.

• Metal implants: Pre-scan safety checklist to prevent projectile risk • Noise: Ear protection for patients and staff due to loud banging/clicking sounds These precautions help mitigate the risks associated with MRI scanning.

Interprets MRI images, identifies abnormalities, and writes diagnostic reports The radiologist plays a crucial role in analyzing the results for clinical decision-making.

Magnetic Resonance Imaging MRI is a non-ionising imaging technique that uses magnetic fields and radio waves.

• Brain & spinal cord • Heart & blood vessels • Joints & skeletal system • Internal organs (liver, kidneys, uterus, breast tissue) MRI is versatile and can visualize various body parts.

TRUE MRI does not expose patients to harmful radiation, making it a safer option for imaging.

gadolinium Gadolinium enhances image quality but has risks for patients with impaired renal function.

• Non-ionising radiation • Excellent soft tissue contrast • Can image the entire body • No known long-term health risks • High spatial resolution images These advantages make MRI a preferred imaging technique in many clinical scenarios.

• Very high cost • Loud noise • Contraindicated for certain patients • Scan duration (20–90 minutes) • Limited availability These disadvantages can affect patient access and comfort during MRI procedures.

• Radiographer • Radiologist • Radiology Nurse / Technologist • Referring Clinician Each professional has specific roles in operating the MRI, interpreting results, and ensuring patient safety.

superconducting magnet This magnet is crucial for aligning hydrogen protons during the MRI process.

The time it takes for hydrogen protons to return to alignment with the magnetic field after excitation Different tissues have varying relaxation times, affecting the image contrast.

• Emission of ultrasound pulses • Reflection at tissue boundaries • Detection of reflected waves • Image construction using distance calculations The transducer converts electrical energy into ultrasound pulses and detects reflections to build a 2D image.

• Higher frequency → higher resolution • Lower frequency → deeper penetration • Trade-off between depth and image clarity The sonographer must choose a compromise between frequency and resolution based on the imaging needs.

• Difference: Anatomical ultrasound images structure; Doppler detects blood flow • Clinical uses: Anatomical for pregnancy monitoring; Doppler for DVT assessment Anatomical ultrasound is used for visualizing organs, while Doppler is used for assessing blood flow direction and speed.

Eliminates air gap between probe and skin The gel ensures efficient transmission of sound waves into the body, by matching the impedence of skin.

• Advantage: Non-ionising, safe for all patients • Disadvantage: Limited by bone and air, cannot image through these structures Ultrasound is cost-effective and portable, but its effectiveness can be hindered by certain anatomical barriers.

Sound with a frequency above 20 kHz Medical ultrasound typically uses frequencies of 1–22 MHz.

• Convex (curvilinear) • Linear array • Phased array Each type is chosen based on the depth of tissue and the area being scanned.

longitudinal This characteristic is essential for understanding how ultrasound interacts with tissues.

• 1–3 MHz: Deep abdominal organs • 3–7 MHz: General abdominal and cardiac imaging • 7–15 MHz: Shallow structures • 18–22 MHz: Superficial structures Different frequencies are used based on the depth and type of tissue being examined.

• Colourless • Non-toxic and non-allergenic • Appropriate viscosity • High conductivity These properties ensure effective transmission of ultrasound waves and patient safety.