Spine and Pelvis Procedures

The right posterior oblique (RPO) position of the left acetabulum will demonstrate the

1. posterior rim of the left acetabulum. 2. left anterior ilioischial column.

The posterior oblique projection of the acetabulum

(Judet method) requires a 45-degree obliquity of the entire midsagittal plane (MSP). In the RPO position, the down side (the right side in this case) will demonstrate the anterior rim of the right acetabulum, the right posterior ilioischial column, and the right iliac wing. When centered to the up side (the left side in this case), the structures demonstrated are the posterior rim of the left acetabulum, the left anterior iliopubic column, and the left obturator foramen. The right iliac wing will be demonstrated in this position.

The posterior oblique positions of the cervical spine

(LPO and RPO) require that the central ray be directed 15° to C4. The posterior obliques demonstrate the intervertebral foramina farther away from the IR. The anterior oblique positions require a 15° caudal angulation and demonstrate the intervertebral foramina closest to the IR.

Male pelvis

- Heavy and thick general structure - Greater, or false, pelvis is deep - Pelvis brim, or inlet, is small and heart-shaped - Acetabulum is large and faces laterally - Pubic angle is less than 90° - Ilium is more vertical

Female pelvis

- Light and thin general structure - Greater, or false, pelvis is shallow - Pelvis brim, or inlet, is large and oval - Acetabulum is small and faces anteriorly - Pubic angle is more than 90° - Ilium is more horizontal

Which of the following vertebral groups form(s) lordotic curve(s)?

1. Cervical 2. Lumbar

Which of the following bones participate in the formation of the acetabulum?

1. Ilium 2. Ischium 3. Pubis

With which of the following does the femoral head articulate?

1. Ilium 2. Ischium 3. Pubis

Which of the following are demonstrated in the lateral projection of the thoracic spine?

1. Intervertebral spaces 2. Intervertebral foramina

Which of the following are appropriate techniques for imaging a patient with a possible traumatic spine injury?

1. Maneuver the x-ray tube head instead of moving the patient. 2. Call for help and use the log-rolling method to turn the patient.

Which of the following is (are) effective in reducing breast exposure during scoliosis examinations?

1. Use of a high-speed imaging system 2. Use of breast shields 3. Use of compensating filtration

When comparing the male and female bony pelves, it is noted that the

1. male pelvis is deeper. 2. female pubic arch is greater than 90°. 3. female greater sciatic notch is wider.

The AP projection of the sacrum requires that the central ray be directed

15° cephalad

In the posterior oblique position of the cervical spine, the central ray should be directed

15° cephalad to C4

The left sacroiliac joint is positioned perpendicular to the IR when the patient is positioned in a

25° to 30° LAO position

Which of the following positions will demonstrate the lumbosacral apophyseal articulation?

30° RPO

The vertebral column is composed of

33 bones divided, from superior to inferior, into cervical, thoracic, lumbar, sacral, and coccygeal regions, with each region having its own characteristic shape. Intervertebral disks between the vertebral bodies form amphiarthrotic joints. The cervical and lumbar regions form lordotic curves; the thoracic and sacral regions form kyphotic curves. An exaggerated thoracic curve is called kyphosis ("hunchback"); an exaggerated lumbar curve is lordosis ("swayback"). Lateral curvature of the vertebral column is called scoliosis.

The thoracic apophyseal joints are

70° to the midsagittal plane and are demonstrated in a steep (70°) oblique position. The thoracic intervertebral foramina, formed by the vertebral notches of the pedicles, are 90° to the MSP. They are therefore well demonstrated in the lateral position. The intervertebral foramina of the thoracic and lumbar vertebrae are also demonstrated in the lateral position.

All of the following are palpable bony landmarks used in radiography of the pelvis

A. pubic symphysis. B. greater trochanter. C. iliac crest.

Which of the following projections can be used to supplement the traditional "open-mouth" projection, when the upper portion of the odontoid process cannot be well demonstrated?

AP or PA through the foramen magnum

Which of the following is a functional study used to demonstrate the degree of AP motion present in the cervical spine?

Flexion and extension laterals

Which of the following should be performed to rule out subluxation or fracture of the cervical spine?

Horizontal beam lateral

Which of the following are demonstrated in the oblique position of the cervical spine?

Intervertebral foramina

Which of the following positions would best demonstrate the left apophyseal articulations of the lumbar vertebrae?

LPO

Which of the following is demonstrated in a 25° RPO position with the central ray entering 1 inch medial to the elevated ASIS?

Left sacroiliac joint

Which of the following positions will provide an AP projection of the L5-S1 interspace?

Patient AP with 30° to 35° angle cephalad

Which of the following bony landmarks is in the same transverse plane as the symphysis pubis?

Prominence of the greater trochanter

What is the name of the condition that results in the forward slipping of one vertebra on the one below it?

Spondylolisthesis

Which of the following is located at the level of the interspace between the fourth and fifth thoracic vertebrae?

Sternal angle

Which of the following statements regarding the male pelvis is (are) true?

The angle formed by the pubic arch is less than that of the female

A lateral projection of the lumbar spine

The intervertebral joints (disk spaces) are well demonstrated. Because the intervertebral foramina, which are formed by the pedicles, are 90° to the MSP, they are also well demonstrated in the lateral projection. The articular facets, forming the apophyseal joints, lie 30° to 50° to the MSP and therefore are visualized in the oblique position.

The degree of anterior and posterior motion is occasionally diminished with

a "whiplash"-type injury. Anterior (forward, flexion) and posterior (backward, extension) motion is evaluated in the lateral position, with the patient assuming the best possible flexion and extension. Left- and right-bending images of the thoracic and lumbar vertebrae are frequently obtained when evaluating scoliosis.

o clearly demonstrate the atlas and axis without superimposition of the teeth or the base of the skull,

a line between the maxillary occlusal plane (edge of upper teeth) and mastoid tip must be vertical. If the head is flexed too much, the teeth will be superimposed. If the head is extended too much, the cranial base will be superimposed on the area of interest. A line between the mentum and the mastoid tip is used to demonstrate the odontoid process only through the foramen magnum (Fuchs method).

To demonstrate the first two cervical vertebrae in the AP projection, the patient is positioned so that

a line between the maxillary occlusal plane and the mastoid tip is vertica

The AP axial projection, or "frog leg" position, of the femoral neck places the patient in a supine position with the affected thigh

abducted 40° from the vertical

A diagnostic image of C1-2 depends on

adjusting the flexion of the neck so that the maxillary occlusal plane and the base of the skull are superimposed (see the dotted lines in Fig. B). Accurate adjustment of these structures will usually allow good visualization of the odontoid process and the atlantoaxial articulation. Too much flexion superimposes the teeth on the odontoid process; too much extension superimposes the base of the skull on the odontoid process.

A diagnostic image of C1-2 depends on

adjusting the flexion of the neck so that the maxillary occlusal plane and the base of the skull are superimposed. Accurate adjustment of these structures will usually allow good visualization of the odontoid process and the atlantoaxial articulation. Should patient anatomy occasionally prevent the usual visualization, the odontoid process can be visualized through the foramen magnum, either AP or PA. In the AP position (Fuchs method), or the PA position (Judd method), the patient's chin is extended to be in line vertically with the mastoid tip (similar to a Waters' or reverse Waters' position). The CR is directed to the midline and perpendicularly at the level of the mastoid tip. The resulting image demonstrates the odontoid process through the foramen magnum. These positions should not be attempted if the patient has suspected, new, or healing fracture, or destructive disease.

The thoracic apophyseal joints

are demonstrated by placing the patient in an oblique position with the coronal plane 70° to the IR (MSP 20° to the IR). This may be accomplished by first placing the patient lateral, then obliquing the patient 20° "off lateral." The apophyseal joints closest to the IR are demonstrated in the PA oblique, and those remote from the IR in the AP oblique. Comparable detail is obtained using either method, because the OID is about the same.

The architectural features of the female pelvis

are designed to accommodate childbearing. The female pelvis as a whole is broader and more shallow than its male counterpart, having a wider and more circular pelvic outlet. The ischial tuberosities and acetabula are further apart. The sacrum is wider and extends more sharply posteriorly. The pubic arch of the man is significantly narrower than that of the woman.

Lateral projections of the cervical spine

are done to demonstrate the intervertebral disk spaces, apophyseal joints, and spinous processes. Apophyseal joints are formed by adjacent superior and inferior articular processes and their facets. Spinous processes are formed by the union of the laminae

Intervertebral joints

are well visualized in the lateral projection of all the vertebral groups. Cervical articular facets (forming apophyseal joints) are 90° to the midsagittal plane and are therefore well demonstrated in the lateral projection. The cervical intervertebral foramina lie 45° to the midsagittal plane (and 15° to 20° to a transverse plane) and are therefore demonstrated in the oblique position.

Flexion and extension views are useful in certain

cervical injuries, such as whiplash, to indicate the degree of anterior and posterior motion

The apophyseal articulations of the thoracic spine are demonstrated with the

coronal plane 70° to the IR

What structure can be located midway between the anterior superior iliac spine (ASIS) and pubic symphysis?

dome of the acetabulum

Spinal column studies are often required for

evaluation of adolescent scoliosis, thus presenting a twofold problem: radiation exposure to youthful gonadal and breast tissues, and significantly differing tissue densities/thicknesses. The use of a high-speed film-screen combination helps reduce the exposure required for the examination. Exposure dose concerns can also be resolved with the use of a compensating filter (for uniform density) that incorporates lead shielding for the breasts and gonads

The pedicle is represented by what part of the "scotty dog" seen in a correctly positioned oblique lumbar spine?

eye

The ASIS, pubic symphysis, and greater trochanter are palpable bony landmarks used in radiography of the pelvis and for localization of the

femoral necks

The uppermost portion of the iliac crest is at approximately the same level as the

fourth lumbar vertebra

In the posterior oblique position of the cervical spine, the intervertebral foramina that are best seen are those

furthest from the IR

There are several surface landmarks and localization points that can help the radiographer

in positioning various body structures. The jugular notch, located at the superior aspect of the manubrium, is approximately opposite the T2-3 interspace. The sternal angle is located opposite the T4-5 interspace. The xiphoid (or ensiform) process is located opposite T10.

An oblique projection of the lumbar spine

is a 45° LPO position demonstrating the apophyseal joints closest to the IR. The apophyseal joints are formed by the articulation of the inferior articular facets of one vertebra with the superior articular facets of the vertebra below. Note the "scotty dog" images that appear in the oblique lumbar spine. Intervertebral foramina are best visualized in the lateral lumbar position.

Scoliosis

is a lateral curvature of the spine and is typically noted in early adolescence. These young patients usually return for follow-up studies, and it is imperative to limit their radiation dose as much as possible. Examining the patient in the PA position is frequently advisable, because the gonadal dose is significantly reduced and there is usually no appreciable loss of detail. Thyroid and breast shields are also a valuable protection, especially for the patient who requires follow-up examinations. Bending images would not be performed on a patient with suspected subluxation or spondylolisthesis, as further serious injury could result.

The 45° oblique position of the lumbar spine

is generally performed for demonstration of the apophyseal joints. In a correctly positioned oblique lumbar spine, "scotty dog" images are demonstrated. The scotty's ear corresponds to the superior articular process, his nose to the transverse process, his eye to the pedicle, his neck to the pars interarticularis, his body to the lamina, and his front foot to the inferior articular process.

The obturator foramen

is the largest foramen in the human skeleton. Blood vessels and nerves pass through this large pelvic foramen. Whereas the ilium, ischium, and pubis make up the pelvis—only two of those bones, the ischium and pubis, make up the obturator foramen. The lateral aspect of the foramen is comprised of the ischium and its rami, while its medial aspect is formed by the pubis and its rami.

The lateral aspect of the obturator foramen is formed by the

ischium

When imaging a patient with a possible traumatic spine injury,

it is appropriate to either maneuver the x-ray tube head or, if the patient must be moved, to use the log-rolling method. This cannot be done by one person; the radiographer must summon assistance. If the patient is on a backboard and in a neck collar, as most patients with suspected spine injury are, it is never appropriate to ask the patient to turn, scoot, or slide over. The only movement that should be permitted is movement of the entire spine, body, and head together, as in log rolling. Any twisting could cause severe and permanent damage to the spinal cord, resulting in paralysis or even death.

because apophyseal joints are positioned 90° to the MSP, they are well visualized in the

lateral projection

To obtain an AP projection of the right ilium, the patient's

left side is elevated 40°

The cervical intervertebral foramina

lie 45° to the midsagittal plane and 15° to 20° to a transverse plane. When the posterior oblique position (LPO or RPO) is used, the cervical intervertebral foramina demonstrated are those further from the IR. There is therefore some magnification of the foramina. In the anterior oblique position (LAO or RAO), the foramina disclosed are those closer to the IR.

Sacroiliac joints

lie obliquely within the pelvis and open anteriorly at an angle of 25° to 30° to the midsagittal plane. A 25° to 30° oblique position places the joints perpendicular to the IR. The left sacroiliac joint may be demonstrated in the LAO and RPO positions with little magnification variation.

The dome of the acetabulum

lies midway between the ASIS and the symphysis pubis. On an adult of average size, a line perpendicular to this point will parallel the plane of the femoral neck. In an AP projection of the hip, the central ray should be directed to a point approximately 2 inches down that perpendicular line, so as to enter the distal portion of the femoral head.

The pars interarticularis is represented by what part of the "scotty dog" seen in a correctly positioned oblique lumbar spine?

neck

The articular facets (apophyseal joints)

of the L5-S1 articulation form a 30° angle with the MSP; they are therefore well demonstrated in a 30° oblique position. The 45° oblique demonstrates the apophyseal joints of L1 through L4.

The short, thick processes that project posteriorly from the vertebral body are the

pedicles

The innominate bone is located in the

pelvis

This 40° abduction from the vertical

places the long axis of the femoral neck parallel to the IR. Adduction is drawing the extremity closer to the midline of the body.

The sacroiliac joints angle

posteriorly and medially 25° to the MSP. Therefore, to demonstrate the sacroiliac joints with the patient in the AP position, the affected side must be elevated 25°. This places the joint space perpendicular to the IR and parallel to the central ray. Therefore, the RPO position will demonstrate the left sacroiliac joint, and the LPO position will demonstrate the right sacroiliac joint. When the examination is performed with the patient PA, the unaffected side will be elevated 25°.

Surface landmarks

prominences, and depressions are very useful to the radiographer in locating anatomic structures that are not visible externally. The costal margin is at about the same level as L3. The umbilicus is at approximately the same level as the L3-4 interspace. The xiphoid tip is at about the same level as T10. The fourth lumbar vertebra is at approximately the same level as the iliac crest.

lateral position

provides the best demonstration of the lumbar bodies, intervertebral disk spaces, spinous processes, pedicles, and intervertebral foramina.

The AP projection of the sacrum

requires a 15° cephalad angle centered at a point midway between the pubic symphysis and the ASIS. The AP projection of the coccyx requires the central ray to be directed 10° caudally and centered 2 inches superior to the pubic symphysis.

AP erect left and right bending images of the thoracic and lumbar vertebrae, to include 1 inch of the iliac crest, are performed to demonstrate

scoliosis

The lordotic curves are

secondary curves; that is, they develop sometime after birth. The cervical and lumbar vertebrae form lordotic curves. The thoracic and sacral vertebrae exhibit the primary kyphotic curves, those that are present at birth.

The forward slipping of one vertebra on the one below it is called

spondylolisthesis. Spondylolysis is the breakdown of the pars interarticularis; it may be unilateral or bilateral and results in forward slipping of the involved vertebra—the condition of spondylolisthesis. Inflammation of one or more vertebrae is called spondylitis. Spondylosis refers to degenerative changes occurring in the vertebra

The posterior oblique positions (LPO and RPO) demonstrate

the apophyseal joints closer to the IR, while the anterior oblique positions (LAO and RAO) demonstrate the apophyseal joints further from the IR

The posterior oblique positions (LPO and RPO) of the lumbar vertebrae demonstrate

the apophyseal joints closer to the IR. The left apophyseal joints are demonstrated in the LPO position, while the right apophyseal joints are demonstrated in the RPO position. The lateral position is useful to demonstrate the intervertebral disk spaces, intervertebral foramina, and spinous processes.

The 45° oblique position of the lumbar spine is generally performed for demonstration of

the apophyseal joints. In a correctly positioned oblique lumbar spine, "scotty dog" images are demonstrated. The scotty's ear corresponds to the superior articular process, his nose to the transverse process, his eye to the pedicle, his neck to the pars interarticularis, his body to the lamina, and his front foot to the inferior articular process

The AP projection of the cervical spine demonstrates

the bodies and intervertebral spaces of the last five vertebrae (C3-7). The cervical apophyseal joints are 90° to the midsagittal plane and are therefore demonstrated in the lateral projection.

The typical vertebra has two parts

the body and the vertebral arch. The body is the dense, anterior bony mass. Posteriorly attached is the vertebral arch, a ringlike structure. The vertebral arch is formed by two pedicles (short, thick processes projecting posteriorly from the body) and two laminae (broad, flat processes projecting posteriorly and medially from the pedicles).

The acetabulum is

the bony socket that receives the head of the femur to form the hip joint. The upper two fifths of the acetabulum is formed by the ilium, the lower anterior one fifth is formed by the pubis, and the lower posterior two-fifths is formed by the ischium. Thus, the acetabulum is formed by all three of the bones that form the pelvis: the ilium, the ischium, and the pubis.

When the pelvis is observed in the anatomic position,

the ilia are seen to oblique forward, giving the pelvis a "basin-like" appearance. To view the right iliac bone, the radiographer must place it parallel to the IR by elevating the left side about 40° (RPO). The left iliac bone is radiographed in the 40° LPO oblique position.

The routine AP projection of the lumbar spine demonstrates

the intervertebral disk spaces between the first four lumbar vertebrae. The space between L5 and S1, however, is angled with respect to the other disk spaces. Therefore, the central ray must be directed 30° to 35° cephalad to parallel the disk space, and thus project it open onto the IR.

Anterior oblique positions (LAO, RAO) of the cervical spine demonstrate

the intervertebral foramina closer to the IR, while posterior oblique positions (LPO, RPO) demonstrate the intervertebral foramina farther from the IR. Intervertebral foramina are formed by the vertebral notches of the pedicles.

AP projection, which demonstrates

the lumbar bodies and disk spaces and the transverse and spinous processes

When a cervical spine is requested to rule out subluxation or fracture,

the patient will arrive in the radiology area on a stretcher. The patient should not be moved before a subluxation is ruled out. Any movement of the head and neck could cause serious damage to the spinal cord. A horizontal beam lateral is performed and evaluated. The physician will then decide what further images are required.

he most prominent part of the greater trochanter is at the same level as

the pubic symphysis—both are valuable positioning landmarks. The ASIS is in the same transverse plane as S2. The ASIS and the pubic symphysis are the bony landmarks used to locate the hip joint, which is located midway between the two points.

The pelvic girdle consists of

two innominate (hip, or coxal) bones, one on each side of the sacrum. Each innominate bone consists of three fused bones—the ilium, ischium, and pubis. Parts of these three bones contribute to the formation of the acetabulum—the socket articulation for the femoral head. The ilia are the large, superior bones whose medial auricular surfaces form the sacroiliac joints bilaterally. The broad, flat portion of each ilium is the ala, or wing; the upper part of the ala forms a ridge of bone called the iliac crest, which terminates in anterior and posterior iliac spines.

The pelvic girdle consists of

two innominate bones, one on each side of the sacrum. Each innominate bone consists of three fused bones: the ilium, ischium, and pubis. Parts of these three bones contribute to the formation of the acetabulum—the socket articulation for the femoral head.