Diagnostic Imaging in Modern Medicine

Study Notes

Essential tool for diagnosing and treating numerous medical conditions across specialties such as orthopedics, vascular, pulmonary, gastrointestinal, obstetric, urologic, and neurology.
Therapeutic radiation is widely utilized, especially in oncology.
Interventional radiology employs real-time imaging for diagnostic and therapeutic procedures.

Ionizing Radiography: Includes X-rays, fluoroscopy, and CT scans; employs ionizing radiation to create images on digital plates.
Magnetic Resonance Imaging (MRI): Utilizes strong magnetic fields and radio frequencies to generate 2D and 3D images; particularly effective in neuroscience and orthopedics.
Nuclear Medicine: Involves the use of radioactive isotopes to monitor decay rates for imaging; used for specialized scans such as SPECT, PET, and thyroid scans.
Ultrasonography: Uses acoustic energy to create images by measuring ultrasound wave reflections; becomes brighter with higher density structures.

Air: Appears black on X-ray, CT, and ultrasound.
Fat: Displays a lighter shade of gray.
Soft Tissue or Fluid: Density affects appearance; denser fluid appears gray, while less dense fluid looks black.
Calcium: Primarily found in bones, but may appear in other structures.
Metal: Appears whitest; typically represents foreign objects or contrast agents.

Key terms include AP (anteroposterior), LAT (lateral), CT without/with contrast (highlights different structures), MRI without/with contrast.
Order only necessary images to confirm or exclude hypotheses; consider radiation exposure, costs, and examination duration.

X-Ray: Useful for fractures, pneumonia, and foreign body localization; risk of radiation exposure.
CT: Effective for organ function and vascular exams; provides better diagnostic accuracy but poses risks of radiation and contrast allergies.
MRI: Ideal for soft tissue examinations with no radiation; offers the greatest diagnostic accuracy but is expensive and time-consuming.
Ultrasound: Non-invasive and useful for superficial structures; dependability increases with skilled sonographers.
Nuclear Medicine: Important for functional imaging and specific disease diagnoses; however, requires special equipment and may be slow.

X-Ray: Fast and inexpensive, good image quality, but limited in internal organ assessments.
CT: Gold standard for many diagnoses, good imaging quality, but with radiation risks.
MRI: Highest diagnostic accuracy with no radiation; long duration and higher costs may limit use.
Ultrasound: Safe, quick, and bedside examinations; image quality heavily relies on the operator’s skill.
Nuclear Medicine: Functional imaging provides specific diagnostic details, but is costly and requires slow processes.

Each imaging modality carries its own safety concerns, especially related to radiation exposure and contrast material allergies, warranting careful consideration in clinical decisions.