Pulmonary cement embolism refers to embolization of polymethyl methacrylate (PMMA) into the lungs. PMMA is a rapidly settling acrylic cement that is often used in vertebroplasty.
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Epidemiology
Its reported incidence is thought to be ~15% (range 4.6-26%) of patients having percutaneous vertebroplasty or kyphoplasty 6,9,11,15.
Clinical presentation
Patients are often asymptomatic 6,12 and it may be detected incidentally for imaging done for another reason.
Pathology
Most leakages are thought to be caused by the injection of polymethylmethacrylate (PMMA) that is still too liquid or by applying too much pressure while injecting the material 13. Other predisposing factors include the needle position with respect to the basivertebral vein and overfilling of the vertebral body 15.
A one year CT follow up study in those with known cement embolism however showed no evidence of any pulmonary reaction or complication 14.
Radiographic features
Plain radiograph
Due to its extreme radiodensity, cement emboli detected on plain film may show multiple radiographically dense opacities with a tubular and branching shape that were scattered sporadically or distributed diffusely throughout the lungs 6. For an accurate appreciation of embolic distribution, cross-sectional imaging is required.
CT
PMMA is extremely high attenuating on CT and due to this reason, PMMA-emboli are better detected on a non-contrast or portal venous phased study compared with a CTPA.
CT may also show extruded cement within the epidural veins, cardiac chambers or other parts of the venous system.
Treatment and prognosis
Reported management options vary, ranging from observation to anticoagulation to embolectomy.
Complications
A recognized concurrent complication to look for is cardiac perforation from cement material lodged in cardiac chambers 10,17,19.
Differential diagnosis
Consider other radiopaque embolic events such as N-butyl-2-cyanoacrylate pulmonary embolism.