Diagnostic ultrasound ( PDFDrive )

752 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
A
B
C
FIG. 20.22 Ectopic Parathyroid Adenoma: Multimodality Imaging in Persistent Hyperparathyroidism. (A) Longitudinal, sonogram demonstrates
an ectopic parathyroid adenoma (calipers) adjacent to the right clavicle (Cl), overlying the subclavian vein (SV) and deep to a prominent collateral
vein (Vn). (B) Artifact from the adjacent clavicle and IV contrast bolus limited CT evaluation (not shown), however, enhanced axial MRI demonstrates
the enhancing ectopic parathyroid adenoma (arrow) overlying the strap musculature (SM) and the subclavian vein. T, Thyroid. (C) Corresponding
right anterior oblique projection from 99m Tc sestamibi (left image) and iodine-123 (middle image) dual-agent subtraction (right image) coronal SPECT
imaging shows a concordant focal area of increased right periclavicular activity (arrows) which corresponds to the ectopic parathyroid adenoma.
half that of the mass, typically 0.1 to 1.0 mL. he tissue becomes
highly echogenic at the moment of injection; the echogenicity
slowly disappears over 1 minute. here is also a marked decrease
in vascularity of the parathyroid adenoma ater alcohol injection,
presumably secondary to thrombosis and occlusion of parathyroid
vessels (Fig. 20.24D). he injections are repeated every day or
every other day until the serum calcium level reaches the normal
range. In most patients, three or fewer injections are necessary.
All patients undergoing parathyroid ethanol ablation require
long-term close follow-up of serum calcium levels to detect
subsequent hypoparathyroidism or, more oten, recurrent
hyperparathyroidism.
he reported adverse efects from ethanol ablation of parathyroid
adenomas have been limited to temporary jaw pain during
the procedure and dysphonia from vocal cord paralysis. Dysphonia
is caused by recurrent laryngeal nerve palsy, which is typically
a transient efect. Patients who have had prior subtotal parathyroid
surgery are also theoretically at increased risk for postablation
hypoparathyroidism, and conservative ablation of only a portion
of the remaining gland is prudent.
he long-term eicacy of ethanol ablation as a treatment of
hyperparathyroidism in patients with primary disease does not
approach that of surgery. 139-142,144,146,152 In addition, postablation
periglandular ibrosis may make future surgical procedures
more diicult. herefore ethanol ablation as a treatment of
primary hyperparathyroidism is reserved for patients who
cannot or will not undergo surgery. Studies on the outcomes of
ethanol ablation in primary hyperparathyroidism report that
most patients had either partial or complete biochemical
improvement, although many of these patients will have recurrent
disease. 141,142,146 hus close clinical and biochemical
follow-up is necessary, and repeat treatments may be required.
Reasons for failure include (1) incomplete ablation of hyperfunctioning
tissue within the treated adenoma and (2) residual