PRINCIPLES OF RADIOLOGY (X-RAY)

Discovery of X-rays

In December 1895, German physicist Wilhelm Roentgen discovered these mysterious rays: X-rays, with X standing for unknown. In recognition of his discovery, Roentgen in 1901 became the first Nobel laureate in physics.

What are X-rays?

They are an electromagnetic radiation emitted by charged particles interactions

Photons which can penetrate through matter

They have no mass or charge They travel at the speed of light

EM Spectrum

X-ray Radiography Machine

FluoroscopyEnables radiologists to visualize X-ray images in real time on a television monitor. In most instances the procedure would involve the administration of some form of 'contrast' agent to outline the region of interest

Fluoroscopy Images

Barium Used to Visualize Intestines

Mammography A mammography machine is an X-ray machine dedicated to breast images. Compared with conventional X-ray techniques, mammograms are obtained with much lower energy X-rays of around 20,000 volts.

Digital Angiography

It is a diagnostic procedure that produces X-ray pictures of blood vessels. A catheter is inserted in the vessel to inject contrast fluid into the lumen of the blood vessel, which then becomes visible on X-ray images.

Digital Angiography Images

First Angiogram(1896, Hankel): Mercury was injected in a post mortem hand

Digital Subtraction Angiography (Mistretta, 1980s)

Digital Angiography Images

Angiogram of The Coronary Arteries

3-D Angiogram of The Brain Arteries

Computerized Tomography (CT)

The technique of CT scanning was developed in 1973 by Hounsfield. A thin fan beam of X-rays generated by a conventional X-ray tube passes through a single 'slice' of a patient through to a bank of X-ray detectors.

CT scan

The number of slices (images) a CT scanner can acquire per revolution of the x-ray tube depends on the number of rows of detectors. Spiral CT units today may be referred to as multislice or multidetector CT scanners.

The current number of slices acquired per revolution in most scanners is 32-64 slices.

These multislice scanners can produce slices that are submillimeter in thickness and can acquire these images in less than a second. Decreasing the slice thickness produces an increase

in the spatial resolution and the ability to visualize smaller structures accurately.

Advantages of ct

Multiple plane visualization Minute details, within slices 3d reconstruction

MRI

More apt in soft tissue pathology diagnosis. images that provide information that is

either T1-weighted, proton densityweighted, T2-weighted, T2∗-weighted, or IR:inversion recovery.

T1-weighted images are best used to demonstrate anatomic detail

joint effusion (arrow). osteomyelitis of the middle phalanx (low signal).

T2-weightedimages (Figure 1–10) are typically used to identify pathologic

conditions

T2-weighted image of same knee with increased signal characteristic of a tear.

Proton density–weighted images indicate the concentration of hydrogen

protons, beneficial in assessing articular cartilage

Proton density–weighted sagittal image of the knee demonstrating an anterior cruciate ligament tear.

Small joint effusion and small popliteal cyst.

T2∗-weighted images may exhibit an angiographic, a myelographic, or an arthrographic effect.

T2∗-weighted coronal image of the knee: Small joint effusion and

small popliteal cyst.

short-tau IR (STIR) and fluid attenuated IR (FLAIR) are used to null the signal coming from a specific tissue such as fat or cerebrospinal fluid (CSF), respectively.

Nulling the signal from a specific tissue allows the surrounding tissue with similar signal characteristics to be visible.

A STIR pulse sequence, commonly used in musculoskeletal imaging, is used to null the signal from fat. This allows better visibility of free fluid and partial or complete tears.

This may be used in combination with a T2-weighted sequence (Figure 1–14) to better visualize pathology that may be difficult to see because of similar high (bright) signals.

When imaging the brain or spinal cord, FLAIR images may be used to null the signal from the CSF, allowing improved visibility of the surrounding periventriclar area of the brain.

STIR pulse sequence demonstrating osteomyelitis (high signal) of the middle phalanx of The same index finger.

with fat suppression.in combination with a T2-weighted sequence (Figure 1–14)

T2∗-weighted sagittal image of the same knee with fat suppression. Small joint effusion and small popliteal cyst.

Different tissues in our body absorb X-rays at different extents:

Bone- high absorption (white)

Tissue- somewhere in the middle absorption (grey)

Air- low absorption (black)

Film Specifics:Name of PatientAge & Date of BirthLocation of PatientDate TakenFilm Number (if applicable)

Film Technical factors:Type of projection (Supine is standard)Markings of any special techniques used

The initial assessment of any xray is the same:

Recognize the Injury: Rule #1Two Orthogonal Views at a

Minimum

Recognize the Injury: Rule #2Long Bones: Need to See the Joints at Both

Ends

(ABCDE’S)2 in MSK Imaging

A = Anatomic appearance, Alignment, Asymmetry

B = Bone Density C = Cartilage (joint, disk spaces),

Contours D = Distribution, Density, Deformity E = Erosions S = Soft tissues

A: ANATOMY

B: BONE MINERALIZATION

C: CARTILAGE

C: CONTOUR

D: DEFORMITY

D: DISTRIBUTION

E: EROSIONS

E: EROSIONS

S: SOFT TISSUE

Cervical spine

Trace the unbroken outline of each vertebrae (including Odontoid on C2). The vertebral bodies should line up with a gentle arch (normal

cervical lordosis) using the anterior and posterior marginal lines on the lateral view. Each body should be rectangular in shape and roughly

equal in size although some variability is allowed (overall height of C4 and C5 may be slightly less

than C3 and C6) . The anterior height should roughly equal

posterior height (posterior may normally be slightly greater, up to

3mm).

Assess four parallel lines. These are: 1. Anterior vertebral line (anterior margin of vertebral bodies) 

2. Posterior vertebral line (posterior margin of vertebral bodies)3. Spinolaminar line (posterior margin of spinal canal)

4. Posterior spinous line (tips of the spinous processes) 

These lines should follow a slightly lordotic curve, smooth and without step-offs. Any

malalignment should be considered evidence of ligmentous injury or occult fracture, and

cervical spine immobilization should be maintained until a definitive diagnosis is made

Trace the unbroken outline of each vertebrae (including Odontoid on C2). The vertebral bodies should line up with a gentle arch (normal cervical lordosis) using the anterior and posterior marginal lines on the lateral view. Each body should be rectangular in shape and roughly equal in size although some variability is allowed (overall height of C4 and C5 may be slightly less than C3 and C6) . The anterior height should roughly equal posterior height (posterior may normally be slightly greater, up to 3mm)

Disc spaces should be roughly equal in height at anterior and posterior margins. 

Disc spaces should be symmetric. 

Disc space height should also be approximately equal at all levels. In older patients, degenative diseases may lead to spurring and loss of disc height.

Preverteral soft tissue swelling is important in trauma because it is usually due to hematoma formation secondary to occult fractures. Unfortunately, it is extremely variable and nonspecific. 

Maximum allowable thickness of preverteral spaces is as follows: 

Nasopharyngeal space (C1) - 10 mm (adult)Retropharyngeal space (C2-C4) - 5-7 mmRetrotracheal space (C5-C7) - 14 mm (children), 22 mm (adults).Soft tissue swelling in symptomatic patients should be considered an indication for further radiographic evaluation. If the space between the lower anterior border of C3 and the pharyngeal air shadow is > 7 mm, one should suspect retropharyngeal swelling (e.g. hemorrhage). This is often a useful indirect sign of a C2 fracture. Space between lower cervical vertebrae and trachea should be < 1 vertebral body.

Some fractures can be very subtle, and soft tissue swelling may be the only sign of fracture. In this case, the lateral view shows only slight soft tissue swelling anterior to C2, and no obvious fracture is seen. On the subsequent CT, a type III dens fracture (fracture of the dens and extends into the body of C2) is demostracted.

Alignment on the A-P view should be evaluated using the edges of the vertebral bodies and articular pillars.

The height of the cervical vertebral bodies should be approximately equal on the AP view.

The height of each joint space should be roughly equal at all levels.

Spinous process should be in midline and in good alignment. If one of the spinous process is displaced to one side, a facet dislocation should be suspected.

Hangman #

Tear drop

Clay shoveller

listhesis

listhesis

spondylolysis

spondylosis

Osteophytes Disc space

narrowing Loss of cervical

lordosis Uncovertebral joint

hypertrophy Apophyseal joint

osteoarthritis Decreased

vertebral canal diameter

teardrop fracture of the C2 vertebral body

the size and displacement of the fracture fragment from the loweranterior vertebral body is further

appreciated.

axial CT image of the C6 vertebra in this image reveals a fracture of the

zygapophysialjoint surface.

sagittal plane CT reconstruction upon close observation reveals a

nondisplaced C7spinous process fracture.

sagittal CT reconstruction reveals injury to C2 known as a hangman’s fracture.

The bilateral fracture pattern associated with a hangman’s fracture.

occipital condyle fracture; such injuries are difficult

to identify with radiography.

base of the odontoid

displacement of the fracture with possible encroachment on the spinal cord

advanced erosive changes of the upper cervical spine, odontoid process and the

atlantoaxial joint

erosive changes along with tendency toward subluxation of C3-4. Degenerative change

throughout the cervical spine.

osteophytic growth has significantly narrowed the intervertebral foramen.

small indentations of the

contrast material representing

spondylitic bars extending

posteriorly from the vertebral

bodies are evident,although no definite disk herniations.

In this axial image of the

post-myelogram CT scan, note the

absence of contrast fillingthe nerve root.

Cervical spine anatomy

ligaments

MRI CS

Preferred imaging modality to address suspicion of associated ligamentous injury and the assessment of the status of nearby neural tissues

MRI CS 1. Vertebral body.2. Intervertebral disc. 3. Posterior body edge adjacent to

disc space (site of potential osteophyte formation).

4. Posterior disc margin (site of potential disc prolapse).

5. Posterior longitudinal ligament (site of potential ossification and cord compression).

(6) Cerebrospinal fluid in front of cord.

(7) Spinal cord. (8) Ligamentum flavum (site of

potential hypertrophy and cord compression)

MRI CS

Axial cervical spine anatomy.

(1 )Anterior vertebral body endplate. (2) Uncus (constituting one side of uncovertebral joint). (3) Vertebral artery within foramen transversarium. (4) Lower

facet. (5) Medial aspect of facet joint. (6) Lamina. (7) Site of attachment ligamentum flavum. (8) Spinous process.

MRI CS major disruption of the C4–5 segment in

this 23-year-old man. Increased signal intensity is evident in the intradiskal space along with injury to

the posterior longitudinal ligament. Edema within the spinal cord is evident spanning multiple levels

around the injury.

MRI CS

A sagittal section T2-weighted MRI of the cervical spine in a 21-year-old man. Note the

signal change present within the spinal cord approximating the C3–4 levels, which is consistent with

edema and a spinal cord contusion. This individual was particularly susceptible to injury because of congenital

stenosis.

MRI CS

The outstanding feature of this sagittal section T2-weighted MR image is the increased

signal intensity consistent with edema from soft tissue injury. The presence of such findings warrants

particular caution to examine scrupulously for the presence of fractures.

MRI CS

T1-weighted MRI revealing basilar invagination. Observe the protrusion of the odontoid

process into the foramen magnum and the resulting displacement of the brainstem.

MRI CS

In this sagittal slice of a T2-weighted MRI of the cervical spine in a 44-year-old man,

changes typical of the age are evident including the decreased signal intensity of the cervical intervertebral

disks, bulging disks (without herniation), and osteophytic lipping at the disk and vertebral body

margins.

MRI CS

In this sagittal section T2-weighted MRI, herniation of the C5–6 disk is evident.

MRI CS

In this axial T2-weighted MR image, the effect of displacing the spinal cord and cervical

nerve root is visible.

MRI CS

A sagittal view T2-weighted MRI revealing advanced degenerative change resulting in

central spinal canal stenosis. Note the absence of signal from the cerebrospinal fluid in the areas of

osteophytic growth and disk bulging.

MRI CS

Although this image is somewhat degraded by motion artifact, involvement of the vertebral

body of C4 with findings consistent with osteomyelitis is readily apparent. Images degraded

from patient motion are frequently a challenge for the physician undertaking interpretation.

MRI CS

In this sagittal section T2-weighted MRI, diffuse metastatic disease is seen in multiple cervical

vertebrae as highlighted by the increased signal intensity.

MRI CS

This T2-weighted MRI with contrast shows areas of altered signal within the spinal cord

consistent with plaque lesions typical of multiple sclerosis. The plaques are not contrast enhanced,

suggesting the image was not captured during a flare of the disease.

Lumbar Spine

Same 4 lines are present in normal alignment

Rectangular bodies Gradual increase in

disc height With caudal

progression in the lumbar spine, the interpedicular distance increases

Lumbar Spine

Triangular canal

Lumbar Spine

Normal AP view

Lumbar Spine

Lumbar Spine

Lateral view radiograph demonstrating wedge compression deformity of the T12 vertebral

body.

Lumbar Spine

Lumbar Spine

Lumbar Spine

Lumbar Spine

Lumbar Spine

Lumbar Spine

Lumbar Spine