Introduction to radiology

Introduction to Radiology.

1. Introduction to radiology Sana Zaheer Qureshi Lecturer B.Sc. Hons MIT King Edward Medical University/ Mayo Hospital, Lahore

2. Radiology Radiology  is the science that uses medical imaging to diagnose and sometimes also treat diseases within the body. Modalities available include: X-ray   radiography Ultrasound C omputed tomography (CT ) Nuclear medicine including positron emission tomography (PET )   Magnetic resonance imaging (MRI ).

3.  Interventional radiology is the performance of (usually minimally invasive) medical procedures with the guidance of imaging technologies.

4. Plain radiography Plain Radiography is used routinely for initial assessment of the patient although it has low specificity and sensitivity as compared to other newer modalities.   There are many disease entities in which the classic diagnosis is obtained by plain radiographs e.g. various types of arthritis and pneumonia, bone tumors (especially benign bone tumors ), fractures, congenital skeletal anomalies, et

5. Makes use of x-rays projected on the patient. X-rays exit the patient and reach the image receptor. X-rays are attenuated according to the body part density.

6. appearance Bones appear white (Maximum attenuation) Air-black (minimum attenuation) Soft tissues-different shades of grays (depending on their relevant densities)

7. floroscopy Uses x-rays as well but provides the live imaging/ video recording. This allows real-time imaging of structures in motion or augmented with a  radiocontrast agent. (refer to the procedures) Results in high patient radiation dose due to long exposure times.

8. Mammography Uses x-rays but of low energy Used to visualize the anatomy and pathologies of breast. Types: Screening (performed in asymptomatic women, more than 35 years of age) Diagnostic (performed in symptomatic women) In women of < 35 years, ultrasound is performed for screening.

9. DEXA Stands for Dual Energy X-ray Absorpitometry Makes use of x-rays to determine the bone mineral density. Helpful in the diagnosis of osteoporosis.

10. Computed tomography CT makes use of x-rays but obtains images in 3 dimensions. Axial slices of body organs are obtained and reconstructed in sagittal or coronal plane. Faster, high sensitivity, better diagnosis are advantages. Non-availability, expensive and high radiation dose are disadvantages. Can be contrast enhanced or plain (without contrast)

11. Ultrasound Medical ultrasonography uses ultrasound (high-frequency sound waves) to visualize soft tissue structures in the body in real time. No ionizing radiations are used. Used to visualize soft tissues mostly. Echocardiography - Ultrasound of heart Doppler imaging- Used to see the blood flow in vessels

12. Magnetic Resonance imaging Uses RF pulses for the transmission and reception of signals An advantage of MRI is its ability to produce images in axial, coronal, sagittal and multiple oblique planes with equal ease . MRI scans give the best soft tissue contrast of all the imaging modalities . MRI has become an important tool in musculoskeletal radiology and neuroradiology.

13. Advantages: MRI has great benefit in imaging the brain, spine, and musculoskeletal system. Contraindications: The use of MRI is currently contraindicated for patients with pacemakers, cochlear implants, some indwelling medication pumps, certain types of cerebral aneurysm clips, metal fragments in the eyes and some metallic hardware due to the powerful magnetic fields and strong fluctuating radio signals to which the body is exposed. 

14. Nuclear medicine Nuclear medicine imaging involves the administration into the patient of radiopharmaceuticals consisting of substances with affinity for certain body tissues labelled with radioactive tracer. The most commonly used tracers are technetium-99m, iodine-123, iodine-131, gallium-67, indium-111, thallium-201 and  fludeoxyglucose (18F) (18F-FDG).

15. The heart, lungs, thyroid, liver, brain, gallbladder, and bones are commonly evaluated for particular conditions using these techniques. While  anatomical detail is limited in these studies, nuclear medicine is useful in displaying physiological  function . The excretory function of the kidneys, iodine-concentrating ability of the thyroid, blood flow to heart muscle, etc. can be measured.