Radiology uses medical imaging to diagnose and sometimes treat diseases. Modalities include X-ray, ultrasound, CT, nuclear medicine including PET, and MRI. Interventional radiology uses imaging to guide minimally invasive procedures. Plain radiography is commonly used for initial assessment but has lower sensitivity than newer modalities. It is useful for visualizing bone tumors, fractures, and arthritis. Ultrasound uses sound waves to image soft tissues in real time without radiation. CT obtains 3D images but has disadvantages of cost and radiation exposure. MRI provides high soft tissue contrast images in multiple planes but has contraindications for patients with metallic implants. Nuclear medicine involves radioactive tracers that accumulate in tissues to evaluate physiological function.

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:
1) X-ray radiography
2) Ultrasound
3) Computed tomography (CT)
4) Nuclear medicine including positron emission tomography (PET)
5) 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.