Diagnostic ultrasound ( PDFDrive )

CHAPTER 23 Overview of Musculoskeletal Ultrasound Techniques and Applications 867
Joint efusions are frequently present in patients with inlammatory
arthritis but are nonspeciic as they may also occur in
patients with osteoarthritis, with infection, and in the setting
of trauma or internal derangement (Fig. 23.21). he diagnosis
of an efusion rests on the visualization of increased volume of
joint luid. Joint luid is typically anechoic but can contain some
mobile low-level echoes. In addition, joint luid is mobile and
compressible. 58 Normal joints contain just a trace of luid, so an
increase in this luid volume constitutes a joint efusion.
Synovitis is determined by the presence of intraarticular
nondisplaceable hypoechoic to hyperechoic sot tissue, which
usually demonstrates hyperemia on color Doppler assessment
(Fig. 23.22). On Doppler assessment, the velocity ilter should
be set to detect low amounts of low, and the gain settings should
FIG. 23.21 Simple Knee Joint Effusion. Anechoic luid is present
within the suprapatellar recess of the knee (arrows). There is concomitant
quadriceps tendinosis (*). F, Distal femur; P, patella.
be adjusted to just below a level where noise is visualized. 59 Either
color Doppler or power Doppler may be more sensitive to low
in the evaluation of synovitis, depending on individual machine,
so familiarity with the hardware being used is important. 60 he
quantity of synovial hyperemia can be graded as described by
Szkudlarek et al. 61 : Grade I (low) hyperemia consists of the
visualization of several single vessel dots. Grade II (moderate)
hyperemia is shown when there are conluent vessel signals
occupying less than half of the visualized synovial tissue. Grade
III (high) represents conluent vessel signals in more than half
of the synovium. Doppler ultrasound has shown high degrees
of sensitivity and speciicity in the diagnosis of synovitis at the
metacarpophalangeal joints in patients with rheumatoid arthritis
when compared with dynamic contrast-enhanced MRI. 61 Ultrasound
has also been shown to have high interobserver and
intraobserver reliability in detection of synovitis. 62
Bone erosion in erosive inlammatory arthritis such as
rheumatoid arthritis can be depicted on ultrasound as a cortical
defect visible in two perpendicular planes 63 (Fig. 23.23). Erosions
may be graded as small (<2 mm), moderate (2-4 mm), or large
(>4 mm). 64 Ultrasound is more sensitive than plain radiographs
in the detection of bone erosion and thus may aid in diagnosis
of early disease. 65 In addition to cortical discontinuity, there may
be acoustic enhancement of marrow subjacent to the inlammatory
bony erosion. 65 Patients with inlammatory arthropathy may also
have associated tenosynovitis, enthesitis, and, in the case of
rheumatoid arthritis, inlammatory periarticular nodules
(rheumatoid nodules) 66 (Fig. 23.24).
Gout is a common inlammatory arthritis with a predilection
for irst metatarsophalangeal joint involvement, caused by
precipitation of uric acid crystals within joints. In patients with
gout, there may be joint efusion, synovial hypertrophy and
hyperemia, sot tissue swelling, and juxtaarticular erosions that
can be large. 67 Intraarticular crystals may be evidenced by the
presence of a characteristic irregular hyperechoic line along
the surface of the normally hypoechoic cartilage, termed the
“double contour sign” 68 (Fig. 23.25). his is distinct from
A
B
FIG. 23.22 Complex Ankle Joint Effusion in Rheumatoid Arthritis. (A) A long-axis image of the tibiotalar joint demonstrates a complex joint
effusion (arrows) with both anechoic luid and echogenic, thickened synovium consistent with synovitis. (B) Color Doppler imaging of the tibiotalar
joint demonstrates marked hyperemia within the echogenic synovium. T, Talus.