Diagnostic Techniques

Ovid: Musculoskeletal Imaging Companion

Editors: Berquist, Thomas H.
Title: Musculoskeletal Imaging Companion, 2nd Edition
> Table of Contents > Chapter 1 – Diagnostic Techniques

Chapter 1
Diagnostic Techniques
Thomas H. Berquist
Douglas S. Fenton
J. Mark McKinney
General concepts for diagnostic imaging techniques will
be discussed in this chapter to avoid redundancy in subsequent
chapters. Appropriate use of imaging techniques is essential for
diagnosis, treatment decisions, and cost containment in today’s medical
Routine Radiography
Today, routine radiography continues to be the most
appropriate screening technique for musculoskeletal disorders.
Appropriate evaluation of routine radiographs results in diagnosis or
selection of the next most appropriate imaging procedure. Specifically,
routine radiographs are essential for proper interpretation of magnetic
resonance (MR) images.
Screen-film radiography is being replaced by computed
radiography at many institutions. Regardless of the system used, it is
essential to ensure proper patient positioning and chronologic labeling
of images.
Multiple views (2–4) are required for minimal evaluation
of osseous and articular anatomy. Specific views will be discussed in
subsequent anatomic chapters. In some cases, fluoroscopically
positioned spot views are useful to optimize positioning and reduce
bony overlap. This approach is especially useful in the foot and wrist.
This technique also is appropriate to evaluate interfaces of
arthroplasties and metal fixation devices. Fluoroscopic positioning is
particularly useful in the shoulder and knee. Stress views can be
obtained using fluoroscopic guidance. Stress radiographs are especially
useful in the ankle, elbow, knee, and wrist.
Suggested Reading
Bender CE, Berquist TH, Stears JG, et al. Diagnostic techniques. In: Berquist TH, ed. Imaging of orthopedic trauma, 2nd ed. New York: Raven Press; 1992:1–37.


The term “ultrasound” refers to mechanical vibrations
whose frequencies are above human detection. Ultrasound imaging uses
frequencies from 2 to 12 MHz. Most musculoskeletal structures examined
are superficial, requiring a 7- to 12-MHz transducer. Doppler
ultrasound for peripheral vascular disease is approximately 8 MHz.
Musculoskeletal applications for ultrasound have
expanded considerably in recent years. The joints, soft tissues, and
vascular structures are particularly suited to ultrasound examination.
Evaluation of cortical and trabecular bone now is feasible and permits
examination of the calcaneus for osteoporosis.
Because of its low cost and availability, ultrasound now
is being used more frequently to evaluate various conditions, as listed
in Table 1-1.
Soft tissue masses
Vascular disease
Ligament/tendon tears
Articular disorders
Foreign bodies
Suggested Reading
Jacobson JA, Van Holsbeek MT. Musculoskeletal ultrasonography. Orthop Clin North Am 1998;29:135–167.
J, Fassell DP, Jacobson JA, et al. An illustrated tutorial of
musculoskeletal ultrasound. Part I, introduction and general
principles. AJR Am J Roentgenol 2000;175:637–645.


Radionuclide Imaging
Multiple agents are available for bone imaging. The
agents selected and imaging techniques used vary with the clinical
indication for examination. Radiopharmaceuticals may be used alone or
in combination.
Bone Scans
Patients are injected intravenously with 10 to 20 mCi (370–740 MBq) of technetium-labeled diphosphonate (Table 1-2). Images are obtained 3 to 4 hours after injection.
  • Primary or metastatic bone lesions
  • Subtle fractures, i.e., stress fractures
  • Battered child
  • Bone pain
Three-phase bone scans are performed using the same
radiopharmaceutical, but with a different imaging sequence. Blood flow
images are obtained in the initial 60 seconds after injection, followed
by blood-pool images 2 to 5 minutes after injection and delayed images
at 3 to 5 hours.
Radiopharmaceutical Dose Physical half-life (h) Remarks
Technetium-99m diphosphonate 10–20 mCi (370–740 MBq) 6 50%–60% in bone at 3–4 h
Technetium-99m sulfur colloid 4–6 mCi (48–222 MBq) 6 Localization: liver 80%–90%, spleen 5%–10%, marrow 1%–5%
Indium-111–labeled leukocytes 0.5–1.0 mCi (18.5–37 MBq) 67
Gallium-67 citrate 2–6 mCi (74–222 MBq) 78 Accumulates in breast milk. Renal excretion first 24 h, then gastrointestinal excretion.
Fluorine-18-deoxyglucose 15 mCi (555 MBq) 1.83 (110 min) Excreted by kidneys; high
uptake in cerebral cortex; variable uptake in myocardium, bowel,
tonsils, parotid glands, and muscles of mastication


  • Stress fractures
  • Differentiation of osteomyelitis from cellulitis
  • Detection of infarction or avascular necrosis
  • Evaluation of reflex sympathetic dystrophy
  • Evaluation of peripheral vascular disease
Single-photon emission (computed tomography [CT]) can be
used in addition to conventional delayed bone imaging to define subtle
lesions, such as pars defects in patients with low-back pain. Computers
reconstruct images in multiple planes.
Bone Marrow Imaging
Patients are injected intravenously with 10 to 15 mCi
(370–555 MBq) of technetium-labeled sulfur colloid. Images are obtained
approximately 15 minutes after injection. Lead shields are placed over
the abdomen to delete counts from the liver and spleen.
  • Identify marrow replacement by neoplasms
  • Define marrow replacement around joint prostheses
Special approaches may be required for specific
indications, such as infection. Several radiopharmaceuticals have been
used in this setting. Three-phase bone scans are sensitive, but not
specific. White blood cells labeled with gallium-67 citrate and
indium-111 or technetium-99m provide more specificity.
Indium-111–labeled leukocyte scans are performed 18 to
24 hours after intravenous injection of 500 mCi (18.5 MBq).
Technetium-labeled white cell or antigranulocyte antibody imaging can
be performed in 2 to 4 hours. This isotope is more available, and image
resolution is superior to that obtained by indium-111 studies. A
disadvantage of technetium is biliary excretion into bowel, which may
obscure portions of the spine and pelvis.
Gallium-67 citrate scans are performed after 5 to 10 mCi
(185–370 MBq) of gallium-67 citrate is injected intravenously. Scanning
is performed 24 to 72 hours after injection.
Combined Studies
Use of multiple radiopharmaceuticals may be required for
special clinical situations, such as failed joint prosthesis or
osteomyelitis. Combined technetium sulfur colloid and
indium-111–labeled leukocytes is useful for evaluating loosening or
infection of joint prosthesis. Combined technetium-99m diphosphonate
and indium-111–labeled leukocytes is useful for osteomyelitis.
Positron Emission Tomography
Positron emission tomography (PET) has provided a new
physiologic approach to imaging musculoskeletal disorders, specifically
infection and neoplasms.


agents include fluorine-18-deoxyglucose, L-methyl-carbon 11-methionine,
and oxygen 15. Fluorine-18 has a half-life of 110 minutes compared with
the shorter half-life of 20 and 21 minutes, respectively, for the other
agents. Therefore, fluorine-18 is used clinically. Fluorine-18
fluorodeoxyglucose imaging demonstrates increased glucose use seen with
these active processes. Patients must fast for 4 hours before the
examination. No sugared beverages should be taken. Normal blood glucose
levels are optimal. Scanning is performed 1 hour after injection.
Images are evaluated, and uptake ratios of abnormal to normal tissues
can be calculated. Early studies demonstrate that PET imaging is more
accurate than combined studies described above for evaluating
infection, chronic infection, and infection associated with joint
replacement arthroplasties. PET is also more useful than conventional
radionuclide studies for detection of tumor activity and metastasis.

Suggested Reading
Winter F, Van de Wiele C, Vogelaers D, et al. Fluorine-18
fluorodeoxyglucose-positron emission tomography: A highly accurate
imaging modality for the diagnosis of chronic musculoskeletal
infections. J Bone Joint Surg 2001;83A:651–660.
McAfer JG. Update on radiopharmaceuticals for medical imaging. Radiology 1989;171:593–601.


Computed Tomography
CT is a fast and efficacious technique for evaluating
the musculoskeletal system. The basic components of the system are a
gantry, which houses a rotating x-ray tube and radiation detectors, and
a movable patient table. The output of the radiation detectors is
manipulated by a computer to produce the images. The table is moved in
increments to obtain axial images with conventional scanners. Spiral
(helical) scanners move the patient continuously as the tube and
detectors rotate, resulting in a spiral volumetric data set.
The computer presents data on a grid matrix, usually
consisting of 512 × 512 picture elements (pixels). Each pixel
represents a volume element (voxel) whose depth is chosen by slice
thickness. Skeletal imaging typically is performed using sections 3 to
5 mm thick, but thinner sections (1.0–1.5 mm) are used for fine detail,
if reformatting, or if three-dimensional reconstruction is required.
CT is particularly suited for evaluating complex
skeletal anatomy in the spine, shoulder, pelvis, foot, ankle, hand, and
wrist. Thin-section images allow reformatting in multiple planes. This
provides excellent osseous and articular detail. Precontrast and
postcontrast images (intravenous iodinated contrast) are useful for
evaluation of soft tissue lesions. CT is useful for evaluating numerous
musculoskeletal disorders, including neoplasms, arthropathies, and
subtle or complex fractures. Specific approaches will be discussed in
later chapters as they apply to specific clinical indications.
Suggested Reading
Berland LL, Smith KL. Multidetector array CT. Once again technology creates new opportunities. Radiology 1998;209:327–329.


Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a proven technique
with expanding musculoskeletal applications. Most imaging is performed
at 1.5 Tesla (T); however, 3T imaging is more common today, and there
are multiple open bore units and extremity units available at lower
field strengths for musculoskeletal imaging. Before considering MRI as
an imaging technique, one must consider certain screening issues and
patient safety factors. We prefer to use a written questionnaire with
specific easily answered questions to improve detection of patients who
may be at risk for MRI. Obvious risk factors, such as cardiac
pacemakers, cerebral aneurysm clips, metallic foreign bodies, and
electronic devices, which may place the patient at risk, can be
detected using the questionnaire and by verbal clarification of
questions from patients. When metallic foreign bodies are suspected,
radiographs or CT should be obtained for confirmation.
Metallic implants may create artifacts that
significantly degrade image quality, especially if the implants contain
ferromagnetic impurities. Fortunately, most orthopedic implants, except
screws, cause minimal local distortion. The extent of image degradation
depends on the size and configuration of the implant. Cast material and
methyl methylacrylate do not create significant image artifacts.
Patient Monitoring and Sedation
Patient age, clinical status, and length of MR
examination must be considered before determining whether sedation or
pain medication is required. Patient monitoring, including blood
pressure, heart rate, respiratory rate, skin temperature, and oxygen
saturation, can be accomplished effectively in the MR gantry.
Claustrophobia, a problem in high-field imaging gantries, is a less
significant problem in lower-field open-bore magnets.
When sedation is required, we use oral medication if
possible. Patient monitoring usually is not required in this setting.
Chloral hydrate is an effective oral medication, especially in children
aged less than 2 years. Alprazolam (Xanax, Pharmacia & Upjohn, New
York, NY), diazepam (Valium, Roche, Nutley, NJ), and ketorolac
tromethamine (Toradol, Roche Nutley, NJ) can be used in adults with
anxiety or claustrophobia. The main disadvantages of oral sedation are
the time of onset and unpredictable effect.
Intravenous sedation requires patient monitoring, but
the effects are more predictable. We use midazolam (Versed, Roche,
Nutley, NJ), fentanyl, and, for the elderly, diphenhydramine (Benadryl,
Pfizer Inc., New York, NY) for intravenous sedation. Patients given
sedation should not drive for 24 hours and must be accompanied if
travel is required after the examination.
Patient Positioning and Coil Selection
Patient positioning considerations include patient size,
body part and structures to be examined, and expected examination time.
The patient should be studied with the most closely coupled coil
(smallest coil that covers anatomy of interest) to achieve the optimal
signal-to-noise ratio and spatial resolution. The torso coil can be
used for the trunk, pelvis, and thigh region. The supine


prone position can be used. The prone position is preferred for
posterior pathology, as soft tissue compression is avoided.
Claustrophobic patients may tolerate the prone position more easily.

Most extremity examinations can be performed with
circumferential, partial volume, or flat coils. Open or flat coils
allow more flexibility for positioning and motion studies. However,
signal drop-off can occur with small flat coils (depth of view limited
to approximately half the coil radius). Newer coils, including dual
switchable coils, allow simultaneous examination of both extremities.
Pulse Sequences and Slice Selection
Pulse sequences should be selected to optimize anatomic
display, enhance lesion conspicuity, and characterize lesions. In many
cases, conventional T1-weighted (SE 500/10) and dual-echo T2-weighted
(SE 2000/20, 80) spin-echo sequences are adequate for lesion detection
and characterization. Fast spin-echo sequences can be performed more
quickly and substituted for conventional spin-echo sequences. Subtle
lesions may require short TI inversion recovery sequences, fat
suppression, or intravenous or intra-articular gadolinium to clearly
define the abnormality. At least two image planes typically are
obtained to clearly define the extent of lesions. Specific protocols
will be provided in subsequent anatomic and pathologic chapters.
Suggested Reading
Berquist TH. General diagnostic techniques. In: Berquist TH, ed. MRI of the musculoskeletal system, 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2006:61–97.


Interventional Techniques
Interventional orthopedic techniques can be used for diagnosis, therapy, and preoperative planning. Table 1-3 lists the indications for arthrography, tenography, and diagnostic/therapeutic injections.
Arthrography has been replaced by MRI, especially for
imaging the knee and shoulder. However, certain patients are not
candidates for MRI. Also, arthrography provides additional information
because of its ability to evaluate joint fluid, measure capsular
volume, and inject anesthetic and/or steroid for diagnostic and
therapeutic purposes.
Today, we most commonly perform arthrograms to confirm
joint access for anesthetic injection to determine the source of pain
or to aspirate fluid to exclude infection.
Tenograms are performed most commonly in the hand,
wrist, foot, and ankle. Anatomic detail is inferior to that obtained by
MRI. However, again,


ability to inject anesthetic to confirm the site of symptoms provides
useful information. Entering the joint or tendon sheath is monitored
fluoroscopically to ensure proper needle position.

Anatomic Region Indication
Spine Facet syndrome
Painful instrumentation (i.e., hooks and wires)
Shoulder Rotator cuff tears
Adhesive capsulitis
Subacromial bursitis
Aspiration of calcium deposits
Elbow Capsule/ligament tears
Loose bodies
Hand and Wrist Ligament tears
Triangular fibrocartilage tears
Localize joint symptoms
Pelvis and Hips Synovial chondromatosis
Labral tears
Snapping iliopsoas tendon
Sacroiliac pain or instability
Pubic symphysis pain
Aspiration of joint effusions
Knee Proximal tibiofibular joint pain
Aspirate joint effusions
Foot and Ankle Ligament tears
Tendon tears
Localize joint symptoms
The injection set devised for orthopedic interventions
is set up to accommodate arthrograms, tenograms, injections, and
aspirations. An overhead fluoroscopic tube may be preferred over a
conventional fluoroscopic unit to improve patient access. The procedure
tray includes sterile drapes, gauze sponges, one 5-mL syringe, two
10-mL syringes, one 30-mL syringe, extension tubing, and a needle box
with short 25-gauge needles for anesthetic injection up to longer
spinal needles for deeper injections and aspirations.
Contrast media, nonbacteriostatic sterile saline to
flush joints or tendon sheaths for culture, culture bottles, and
medication for diagnostic or therapeutic injections are included.
Medications include 1% lidocaine (Xylocaine, AstraZeneca, Wilmington,
DE), 0.25% bupivacaine (Marcaine, AstraZeneca, Wilmington, DE), and
triamcinolone (Kenalog-40, Bristol-Myers Squibb, New Princeton, NJ).
Specific techniques will be discussed in later anatomic chapters, but facet injections and discograms will be discussed here.
Facet Injections
Facet injections are performed most commonly in the
lumbar spine. This technique is useful for preoperative planning,
localization of the source of pain, and postoperative evaluation.
Patients with facet syndrome present with low-back pain that may
radiate to the gluteal region or lower extremity.
Routine radiographs and CT should be reviewed, if
available, to assess the extent of facet joint abnormalities. The facet
joints to be injected are selected, and the patient is placed on the
fluoroscopic table in the prone position. The patient is rotated with
the involved side up to align the facet joint. Each joint to be
injected should be positioned carefully. Sterile preparation is used,
and local anesthetic is injected over the involved joint(s). A 22-gauge
spinal needle generally is adequate to enter the joint. Contrast medium
can be used to confirm needle position. One milliliter of bupivacaine
can be injected if the technique is purely diagnostic. For therapeutic
injections, we use a 2:1 mixture of bupivacaine and triamcinolone.
Discography has been a controversial technique over the
years, but it does play a useful role in assessing disc morphology and
localizing patient symptoms. Combined CT and discography can be
particularly useful for evaluating lumbar disorders.
Patients are positioned in a manner similar to that used
for facet injections. A posterolateral approach is used most often,
after sterile preparation and local anesthetic is injected along the
needle entry path. The L5-S1 disc is more difficult to enter and may
require a coaxial needle approach. The first needle is advanced to the
margin of the disc, and a second Chiba needle with a slight distal bend
is placed through the first needle and into the disc.
The normal disc will accept 2 to 2.5 mL of contrast
medium. Antibiotic is often added to the contrast medium. A
degenerative disc may accept a larger


In this setting, contrast may extend into the annulus and beyond.
Distention of the disc space may recreate or exaggerate the patient’s

Complications of Arthrotenography and Diagnostic/Therapeutic Injections
Arthrotenography and diagnostic injections are
relatively benign procedures. The main concerns are the contrast media
and drug allergies. Infection is rare if sterile technique is used.
Painful effusions can occur as a result of acute synovitis. The
effusions usually occur shortly (<12 hours) after injection and may
require joint aspiration for therapy.
Injections in certain regions, specifically in the spine
or near nerve roots, may cause inadvertent nerve block with numbness
and reduced function. These problems generally are transient and clear
up after the anesthetic effect resolves.
  • 22-gauge, 3.5-inch (or 6-inch) spinal needle
  • 60-mL syringe with 25-gauge, 1.5-inch needle with 1% lidocaine for skin anesthesia
  • 20-mL syringe for myelographic contrast
  • Connecting tubing
  • Povidone iodine (Betadine, Purdue Products, Stamford, CT) and alcohol scrub
  • Sterile towels and drape
  • Cerebrospinal fluid (CSF) collection tubes
  • Nonionic myelogram contrast
    (Omnipaque-180 [iohexol] for lumbar spine; Omnipaque-240 for the
    thoracic spine; Omnipaque-300 for cervical; Amersham Health Inc.,
    Buckinghamshire, United Kingdom)
General Considerations
  • Signed consent form: acknowledge spinal
    headache, bleeding, infection, neural injury, allergic reactions,
    seizures, nausea, and vomiting
  • Tray with medication used for contrast reactions and other complications
Lumbar Myelogram
  • Patient prone with head of table elevated 5 to 10 degrees.
  • Sterile preparation and local anesthetic at entry site.
  • Needle entry at L2–3 level or below, with midline or slight (5–10 degree) parasagittal approach
  • P.12

  • Needle advanced with fluoroscopic
    guidance. Always keep the stylet in the needle when advancing. The
    bevel of the needle should be oriented vertically when entering the
    dura. When CSF is obtained, advance the needle 2 mm to ensure
    intrathecal position.
  • Collect fluid specimens as clinically indicated.
  • Connect contrast syringe with tubing to puncture needle.
  • Contrast injection is monitored
    fluoroscopically. The patient may feel fullness, or leg pain may
    increase during injection. The patient should receive no more than 3 g
    of iodine or 16.5 mL of Omnipaque-180.
  • Reinsert the stylet in the needle and remove after contrast injection.
  • Standard radiographs in anteroposterior
    (AP), bilateral 30-degree and 45-degree oblique, and lateral views.
    Turn patient supine and repeat AP and lateral views of conus region.
Cervical Myelogram (Lumbar Approach)
  • Cervical myelograms are performed similar to lumbar studies except Omnipaque-300 is used (no more than 10 mL).
  • Patient’s ankles are strapped and connected to the table bottom.
  • Patient’s head is extended and a cushion is placed under the chin. Arms are at the side.
  • Patient is tilted head down,
    fluoroscopically evaluating the head of the contrast column as it
    enters the cervical region. Table is flattened when contrast comes into
    the cervical subarachnoid space.
  • Routine images include AP, bilateral 45-degree oblique, and lateral views.
  • Patient is taken to the CT suite for further imaging.
Cervical Myelogram (Cervical Approach)
  • Patient is prone or in the left lateral decubitus position with table flat.
  • Fluoroscopic guidance is used to enter
    the subarachnoid space between C1–2 spinous processes after sterile
    preparation and subcutaneous local lidocaine anesthetic.
  • CSF is collected for laboratory studies.
  • Same amount of Omnipaque-300 is used as with the lumbar approach.
  • The stylet is reinserted in the needle, and the needle is removed before obtaining images.
  • Routine AP, 45-degree oblique, and lateral images are obtained.
  • Patient is taken to CT laboratory for further imaging.
Thoracic Myelogram
  • Complete myelogram—cervical, thoracic, and lumbar—usually is obtained.
  • Omnipaque-240 is used and can be injected in manner similar to that used for the lumbar approach.
  • P.13

  • 12 mL of contrast is required for a complete study.
  • Images are obtained in both lateral decubitus positions, as well as supine and prone (AP and posteroanterior).
  • Blocks can be marked on the skin surface.
  • CT usually is combined with thoracic myelograms.
Angiography is performed for selected musculoskeletal
disorders. Trauma, neoplasms, and treatment of posttraumatic bleeding
or preoperative tumor embolic therapy are indications.
  • Selective catheterization of the affected anatomic region is recommended to optimize angiographic visualization.
  • Angiographic images should be evaluated for:
    • Intimal tears
    • Pseudoaneurysms
    • Occlusions
    • Extravasation
    • Emboli
  • Selective catheterization of the affected anatomic region is recommended to optimize angiographic visualization.
  • Angiographic images should be evaluated for:
    • Specific arteries and veins participating in perfusion and drainage of the neoplasm
    • Parasitization of remote arteries
    • Vascular encasement or occlusion
    • Significant arteriovenous shunting
  • Posttraumatic hemorrhage can be controlled by selective catheterization and embolization.
  • Embolization should be selective to prevent tissue ischemia or necrosis.
  • Embolic agents most commonly used are microcoils, Gelfoam, and glue.


Preoperative Tumor
  • Preoperative arterial embolization is particularly helpful in controlling intraoperative bleeding from hypervascular neoplasms.
  • Selective embolization should be performed to prevent nontarget tissue ischemia and necrosis.
  • Embolic agents most commonly used are polyvinyl alcohol particles, microspheres, Gelfoam, and glue.

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