Lecture:2 INTRODUCTION TO RADIOLOGY

 Students should be able to understand different views of normal and abnormal x-rays  Students should understand the basic theories of various Imaging methods  Student should appreciate the abnormal findings in Imaging Objectives

 Manual therapy techniques demands advanced understanding of joint mechanics.  Provide a more comprehensive evaluation of our patient and ultimately better outcomes Why do PT need to know it?

 X-ray  Computed Tomography  Magnetic Resonance Imaging Diagnostic Imaging choices

X-rays are invisible to the human eye Penetration of body by x-rays and the ionization of the atoms on the film result in the image Plain films are without contrast Radiography

Air –Black Fat – gray black Organs, muscles, soft tissue - shades of gray (water based) Bone –White Metal – White More radiation absorbed the lighter the Image Radiodensity

Radio density (decreasing to increasing)

Arthrography: synovial joints Myelography: spinal cord, nerve roots and dura mater Fluoroscopy: dynamic or continuous radiograph of a physiologic function Contrast Enhanced Radiographs

Imagine patient standing in front of you in anatomic position Left or right is labeled Viewing

Minimum of 2 radiographs at right angle to each other for diagnostic purposes  Anteroposterior (A/P)  Lateral  Oblique Projections

Body section radiology Developed in 1970, Allows evaluation of series of slices Computer can make it 3D More sensitive to each tissue type Useful with fractures of irregularly shaped bones Excellent for image bone, intra-articular and some Tumors Computed Tomography

Slice of images: 1- 10mm thick Sagittal plane Frontal plane Horizontal plane Anatomical Planes

Axial Image Air – black Fat – black Muscles – gray Bone cortex – white Bone marrow - gray CT Scan

Discovered by Purcell and Bloch in 1945 Won Nobel prize in for this discovery 1953 Magnetic Resonance Imaging

Non-ionizing radiation Produces information via the interaction of tissue with radio frequency waves in a magnetic field Image is based on re-emission of absorbed radio frequencies in the magnetic field. MRI

Any nucleus with an odd no of protons and neutrons will have an intrinsic spin This induces a small magnetic field around the atomic nuclei which aligns in the direction of the magnetic field Hydrogen is most abundant in the human body. MRI: a map of hydrogen atoms in the body Theory

MRI – creates radio wave Produces a steady magnetic field 30,000 x stronger than EARTH’S magnetic field. MRI

When MRI (radio wave) is turned off, the hydrogen protons will return to resting state, releasing energy The energy (like X-ray) is a form of radio wave which detected by the radio wave receiver and sent to the computer Computer software will generate the images Where is resonance?

The radio waves sent to the body are short pulses of very precise strength and frequency. By changing the strength, frequency and timing of radio wave pulses produces T1 or T2 weighted images. T1 versus T2 Images

T1 image (Fat-enhanced image) Air – dark T1 Images Fat – very bright Bone marrow – Bright Good for Anatomical study Muscles – dark Bone cortex – dark

T2 MRI image (water- enhanced image) Air – dark Fat – intermediate dark Muscles – dark Bone cortex – dark Bone marrow – intermediate dark Good for pathological studies. T2 Images

Plain film is the first diagnostic tool used. Inverse relationship between the amount of Radio density of an object and the blackening of the film. Air images the blackest. MD usually orders at least 2 views as close to 90 degrees to each other to view 3D. Routing projections ordered are AP, lateral and oblique Principles of Radiography

ABCs is a popular systemic approach to evaluating radiographs Alignment Bones Cartilage Soft Tissue General Principles

Alignment General Principles – General contour of bone General skeletal architecture Alignment of bones relative to adjacent bones

Bone Density General Principles General bone density – Texture abnormalities – Local Bone density

Cartilage Space General Principles Joint space width Subchondral bone Epiphyseal plates

Soft Tissues General Principles Muscles Fat pads Joint capsule Periosteum

Rheumatoid Arthritis Radiographic Finding of Common Pathologies Soft tissue changes Articular erosions Joint space narrowing Osteoporosis Joint deformities Changes in cervical spine

Rheumatoid Arthritis The characteristics of RA are present in both hips: articular erosions, joint space narrowing, osteoporosis and joint deformities. The right is further advanced in destruction. destruction

Osteoarthritis (Degenerative Joint disease) Joint space narrowing Subchondral sclerosis Osteophyte formation Cysts or pseudo cysts Soft tissue swelling Joint deformities

Osteoarthritis The hallmarks of DJD are subchondral sclerosis, joint space narrowing and Osteophyte formation. This is a lateral view of the knee

Osteoporosis Cortical thinning Trabecular changes Fractures Osteopenia

Osteoporosis Osteoporosis in the thoracic spine can result in trabecular changes that result in compression fractures due to destruction of the bone.