AJR 2002; 179:495-502
© American Roentgen Ray Society
Hyperfunctioning Parathyroid Tissue: Spectrum of Appearances on Noninvasive Imaging
Michael B. Gotway1,2,
Jessica W. T. Leung3,
Gretchen A. Gooding4,
Harold I. Litt2,
Gautham P. Reddy2,
Eugene T. Morita2,
W. Richard Webb2,
Orlo H. Clark5 and
Charles B. Higgins2
1 Department of Radiology, San Francisco General Hospital, Rm. 1x 55A, Box
1325, 1001 Potrero Ave., San Francisco, CA 94110.
2 Department of Radiology, University of California, Rm. M-391, 505 Parnassus
Ave., San Francisco, CA 94143.
3 Department of Radiology, Brigham and Women's Hospital, Harvard Medical School,
75 Francis St., Boston, MA 02115.
4 Department of Radiology, Veterans Affairs Medical Center, 4150 Clement St.,
San Francisco, CA 94121.
5 Department of Surgery, University of California, Mt. Zion Hospital, Box 1674
C347, Surgery Faculty Practice, 2330 Post St., Rm. 420, San Francisco, CA
94115.
Received January 4, 2002;
accepted after revision February 13, 2002.
Address correspondence to M. B. Gotway.
Introduction
Hyperparathyroidism is a common clinical condition most often caused by
single or multiple adenomas and less commonly by gland hyperplasia;
parathyroid carcinoma is a rare cause of hyperparathyroidism. Experienced
surgeons may cure 95% of patients with hyperparathyroidism without the need
for imaging guidance [1]. When
hyperparathyroidism recurs or persists after surgery, surgical cure rates fall
to 60% if imaging guidance is not used. Noninvasive methods used to evaluate
patients with hyperparathyroidism include sonography, CT, scintigraphy, and MR
imaging. A single cross-sectional study may be used to localize the side of
hyperfunctioning parathyroid tissue before cervical exploration for patients
initially diagnosed with hyperparathyroidism. For patients with recurrent or
persistent hyperparathyroidism, a combination of noninvasive imaging methods,
often an anatomic method such as MR imaging and a functional method such as
99mTc sestamibi scintigraphy, are used. Familiarity with the
various imaging appearances of hyperfunctioning parathyroid tissue is required
for an accurate diagnosis.
Anatomy
Parathyroid glands, commonly four in number, are usually located near the
posterior aspect of the thyroid gland. The superior parathyroid glands may be
ectopically located in the thyroid gland, the posterior mediastinum, the
carotid sheath, or adjacent to the esophagus. Ectopic inferior parathyroid
tissue is usually found in the thymus
[2].
Sonography
Parathyroid glands should be scanned using a high-resolution linear
transducer (
10-MHz) to achieve maximal spatial resolution. A lower
frequency transducer may occasionally be used to achieve a greater depth of
penetration (Fig.
1A,1B,1C).
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Fig. 1B. —50-year-old man with hyperparathyroidism. Longitudinal
sonogram obtained with 6-MHz linear transducer shows deeper tissue penetration
than revealed in A. Note hypoechoic focus (cursors) with poor
sound transmission, consistent with parathyroid adenoma. Although sonographic
evaluation of patients with hyperparathyroidism generally requires use of
high-frequency (7- to 15-MHz) linear transducers to achieve maximal spatial
resolution, care is required to visualize posterior aspects of thyroid gland,
thereby ensuring that most common position for abnormal parathyroid tissue is
evaluated.
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Abnormal parathyroid tissue is usually hypoechoic or anechoic relative to
the thyroid tissue, without sound transmission, and closely related to the
posterior aspect of the thyroid gland. Areas of increased echogenicity may be
encountered in larger abnormal parathyroid glands
(Fig. 2). When abnormal
parathyroid glands exceed 1 cm, color and power Doppler sonography may reveal
vascularity in the lesion (Fig.
3A,3B),
particularly in parathyroid carcinomas
(Fig. 4).
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Fig. 2. —54-year-old man with hyperparathyroidism. Longitudinal
sonogram (7-MHz linear transducer) shows mass (large arrows) with
mixed hypoechoic and hyperechoic foci (small arrows), representing
parathyroid adenoma. Hyperechoic foci may occasionally be encountered in
larger adenomas.
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Fig. 3A. —45-year-old man with hyperparathyroidism. Gray-scale sonogram
(8-MHz linear transducer) reveals hypoechoic lesion (cursors) in neck
with no sound transmission, consistent with parathyroid adenoma.
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Fig. 4. —62-year-old man with parathyroid carcinoma. Transverse color
Doppler sonogram (8-MHz linear transducer) of neck reveals hypoechoic nodule
(arrows) with poor sound transmission and extensive vascularity.
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The accuracy of sonography for the detection of abnormal parathyroid
tissue, in patients who underwent surgery and in those who did not, ranges
from 34% to 83% [2]. This
sensitivity diminishes in patients with secondary hyperparathyroidism and
recurrent or persistent hyperparathyroidism because of the higher frequency of
hyperplastic glands (as opposed to adenomas) in the former and the higher
prevalence of ectopic adenomas in the latter.
CT
Patients undergoing CT for the evaluation of hyperparathyroidism should be
scanned volumetrically with a thin-section technique after IV contrast
administration.
Abnormal parathyroid glands enhance intensely after contrast
administration. The CT diagnosis of abnormal parathyroid tissue requires
identification of an enhancing nodule in locations characteristic for
hyperfunctioning parathyroid glands, such as posterior to the thyroid gland
(Fig. 5).
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Fig. 5. —45-year-old man with recurrent hyperparathyroidism.
Contrast-enhanced axial CT scan (collimation, 5 mm; window width, 440 H;
level, 40 H) reveals large, intensely enhancing nodule just posterior to
inferior aspect of right thyroid gland (arrow), consistent with
parathyroid adenoma.
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CT sensitivity for the detection of abnormal parathyroid tissue ranges from
46% to 87% [2].
Scintigraphy
Scintigraphic methods for the evaluation of patients with
hyperparathyroidism include 201TI chloride-99mTc
pertechnetate subtraction scintigraphy and 99mTc sestamibi
scintigraphy, with or without 123I or 99mTc
pertechnetate subtraction. 99mTc sestamibi scintigraphy has nearly
supplanted other techniques as the primary scintigraphic method used for the
preoperative localization of hyperfunctioning parathyroid tissue.
201TI chloride is concentrated by both thyroid and parathyroid
glands, whereas 99mTc pertechnetate is concentrated only by the
thyroid gland. Therefore, if both agents are administered and the
99mTc pertechnetate images are subtracted from the 201TI
chloride images, the remaining activity should be localized to parathyroid
tissue. Because iodine, like 99mTc pertechnetate, selectively
concentrates in the thyroid gland, orally administered 123I may
also be used to obtain subtraction images.
99mTc sestamibi is initially concentrated in the thyroid gland
and abnormal parathyroid tissue and then differentially cleared from these
organs in a time-dependent manner, washing out of the thyroid more rapidly
than abnormal parathyroid tissue. The differential clearance of
99mTc sestamibi allows dual-phase 99mTc sestamibi
scintigraphy to selectively image hyperfunctioning parathyroid tissue.
Hyperfunctioning parathyroid tissue appears as a focal area of increased
tracer uptake on the 201Tl portion of a
201Tl-99mTc pertechnetate subtraction study (Figs.
6A and
6B). Similarly,
hyperfunctioning parathyroid glands appear as foci of increased tracer uptake
on 99mTc sestamibi scintigraphy (Figs.
6C and
6D). Abnormal parathyroid
tissue may be rendered more conspicuous using 123I subtraction
(Figs.
7A,7B
and 8) or by performing
delayed imaging several hours after tracer administration
(Fig. 6D).
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Fig. 6A. —201Tl-99mTc pertechnetate subtraction
scintigrams in 61-year-old man with hyperparathyroidism after cervical
exploration. Planar scintigram after IV injection of 2 µCi (74 MBq)
201Tl shows tracer uptake in thyroid gland and small nodular focus
of tracer uptake along inferior border of right lobe of thyroid gland
(arrow), representing parathyroid adenoma.
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Fig. 6B. —201Tl-99mTc pertechnetate subtraction
scintigrams in 61-year-old man with hyperparathyroidism after cervical
exploration. Planar scintigram after IV injection of 10 µCi (370 MBq)
99mTc pertechnetate shows normal distribution of tracer in thyroid
gland. Note that focus of tracer uptake in A is not present on
99mTc pertechnetate portion of examination.
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Fig. 6C. —201Tl-99mTc pertechnetate subtraction
scintigrams in 61-year-old man with hyperparathyroidism after cervical
exploration. Early (20-min) planar scintigram after IV injection of 26 µCi
(962 MBq) of 99mTc sestamibi shows focus of activity localized to
inferior aspect of right lobe of thyroid gland, representing parathyroid
adenoma (arrow).
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Fig. 6D. —201Tl-99mTc pertechnetate subtraction
scintigrams in 61-year-old man with hyperparathyroidism after cervical
exploration. Delayed (2-hr) planar scintigram shows relatively improved
conspicuity of parathyroid adenoma (arrow) compared with C.
Note improved resolution of 99mTc sestamibi scintigram compared
with A. Improved resolution, because of more favorable energy of
99mTc photons, is one advantage 99mTc sestamibi has
compared with 201Tl imaging.
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Fig. 7A. —99mTc sestamibi-123I subtraction
scintigraphy in 58-year-old man with recurrent hyperparathyroidism after
cervical exploration. Planar scintigram obtained 20 min after IV injection of
25 µCi (925 MBq) 99mTc sestamibi reveals focus of tracer uptake
just cranial to superior aspect of left lobe of thyroid gland
(arrow), consistent with parathyroid adenoma.
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Fig. 7B. —99mTc sestamibi-123I subtraction
scintigraphy in 58-year-old man with recurrent hyperparathyroidism after
cervical exploration. Planar scintigram after subtraction of 123I
portion of study. 123I localizes in thyroid gland and not within
hyperfunctioning parathyroid tissue; therefore, 123I subtraction
removes tracer activity in thyroid gland, increasing conspicuity of abnormal
parathyroid tissue (arrow) cranial to superior aspect of left lobe of
thyroid gland. Photopenic area in center of image represents subtracted
thyroid tissue activity. Similar subtraction techniques may be performed using
pertechnetate in place of 123I. (Courtesy of Newberg A,
Philadelphia, PA)
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Fig. 8. —99mTc sestamibi-123I subtraction
scintigram in 45-year-old woman with hyperparathyroidism. Planar image
obtained after subtraction of 123I portion of study reveals focus
of increased tracer uptake (large arrow) along inferior aspect of
left lower portion of photopenic area, representing subtracted thyroid gland
activity, consistent with parathyroid adenoma. Tracer uptake at superior
aspect of image (small arrows) represents salivary tissue. (Courtesy
of Newberg A, Philadelphia, PA)
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The sensitivity of 201T1-99mTc pertechnetate
subtraction scintigraphy ranges from 60% to 87%; accuracy for mediastinal
ectopic glands is about 70% [2,
3]. Accuracy rates for
99mTc sestamibi scintigraphy for abnormal parathyroid gland
detection, particularly with the use of single-photon emission tomography,
exceed 90% [2,
4,
5]. 99mTc sestamibi
scintigraphy is also accurate for the detection of mediastinal parathyroid
adenomas [2].
MR Imaging
The MR imaging technique for the evaluation of patients with
hyperparathyroidism requires thin-section ECG-gated or peripherally gated
imaging of the neck with a phased array coil. Chest imaging is also performed
using a torso coil. T1-weighted images, unenhanced and contrast-enhanced (with
fat saturation), are obtained in the neck and chest. Fast spin-echo
T2-weighted images, with or without fat saturation, are obtained in the neck
[2].
The most common appearance of hyper-functioning parathyroid glands on MR
imaging is isointense-to-low signal intensity on T1-weighted images and high
signal intensity on T2-weighted images, with intense contrast enhancement
(Fig.
9A,9B,9C).
Correct diagnosis depends on showing that the suspected lesion resides in a
location typical for hyperfunctioning parathyroid glands
[2,
6]. Occasionally, high signal
intensity may be encountered on T1- and T2-weighted images, reflecting gland
hemorrhage or cystic components (Figs.
10A,10B,10C
and
11A,11B).
Low signal intensity may rarely be seen on both sequences, indicating
fibrosis, old hemorrhage, and cellular degeneration. The signal pattern of the
abnormal parathyroid tissue has been shown to correlate with the histologic
characteristics of the abnormal glands
[7]. MR imaging accurately
detects ectopic hyperfunctioning parathyroid tissue
[8] (Figs.
10A,10B,10C,11A,11B,12A,12B,12C,13A,13B,13C,14).
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Fig. 9A. —45-year-old man with recurrent hyperparathyroidism after
cervical exploration. Axial T1-weighted MR image (TR/TE, 500/8) obtained
through lower neck reveals nodule (arrow) just caudal to right lobe
of thyroid gland that is slightly hypointense relative to skeletal muscle.
Location and appearance are typical of parathyroid adenoma.
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Fig. 9B. —45-year-old man with recurrent hyperparathyroidism after
cervical exploration. Axial fast spin-echo T2-weighted MR image (4000/105) at
same level as A shows lesion (arrow) is hyperintense relative
to skeletal muscle, also characteristic of hyperfunctioning parathyroid
tissue.
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Fig. 9C. —45-year-old man with recurrent hyperparathyroidism after
cervical exploration. Enhanced axial T1-weighted fat-saturated MR image
(500/8) reveals that lesion (arrow) enhances brightly. Intense
enhancement is typical of hyperfunctioning parathyroid tissue. (Reprinted with
permission from [2])
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Fig. 10A. —55-year-old woman with renal disease and hyperparathyroidism.
Axial T1-weighted MR image (TR/TE, 500/8) shows nodule (arrow) with
signal intensity slightly greater than adjacent skeletal muscle in left
sternocleidomastoid muscle. Increased signal intensity on T1-weighted MR image
is somewhat unusual for hyperfunctioning parathyroid tissue.
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Fig. 10B. —55-year-old woman with renal disease and hyperparathyroidism.
Axial fast spin-echo T2-weighted MR image (4000/105) shows nodule
(arrow) has markedly increased T2 signal intensity compared with
adjacent skeletal muscle.
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Fig. 10C. —55-year-old woman with renal disease and hyperparathyroidism.
Enhanced axial T1-weighted fat-saturated MR image (500/8) reveals intense
enhancement of nodule (arrow). (Reprinted with permission from
[6])
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Fig. 11A. —85-year-old woman with recurrent hyperparathyroidism. Axial
T1-weighted MR image (TR/TE, 500/8) obtained through upper mediastinum shows
right paratracheal mass (arrow) with mildly increased T1 signal.
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Fig. 11B. —85-year-old woman with recurrent hyperparathyroidism. Axial
T2-weighted MR image (4000/90) shows hyperintense T2 signal in nodule
(arrow). Combination of hyperintense T1 and T2 signals suggests that
lesion is cystic. Cystic parathyroid adenoma was proven at surgery. (Reprinted
with permission from [8])
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Fig. 12A. —61-year-old woman with persistent hyperparathyroidism after
cervical exploration. e = esophagus. Axial T1-weighted MR image (TR/TE, 550/8)
obtained through lower neck reveals isointense nodule (arrow)
immediately posterior to esophagus.
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Fig. 12B. —61-year-old woman with persistent hyperparathyroidism after
cervical exploration. e = esophagus. Axial fast spin-echo T2-weighted MR image
(4000/90) reveals nodule (arrow) is hyperintense. Note thin rim of
low-signal-intensity tissue surrounding lesion, characteristic of parathyroid
adenomas.
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Fig. 12C. —61-year-old woman with persistent hyperparathyroidism after
cervical exploration. e = esophagus. Enhanced axial T1-weighted fat-saturated
MR image (550/8) shows nodule (arrow) enhances intensely. Signal
intensity patterns are characteristic of parathyroid adenoma. Paraesophageal
position is recognized, but uncommon ectopic location. (Reprinted with
permission from [2])
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Fig. 13A. —36-year-old man with recurrent hyperparathyroidism after
cervical exploration. Axial T1-weighted MR image (TR/TE, 500/8) obtained
through upper neck reveals iso- to low-intensity nodule (arrow) in
left retropharyngeal space.
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Fig. 13B. —36-year-old man with recurrent hyperparathyroidism after
cervical exploration. Axial fast spin-echo T2-weighted MR image (4000/90)
shows increased T2 signal intensity (arrow) in lesion.
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Fig. 13C. —36-year-old man with recurrent hyperparathyroidism after
cervical exploration. Enhanced axial T1-weighted fat-saturated MR image
(500/8) shows intense enhancement of nodule (arrow), characteristic
of parathyroid adenoma. (Reprinted with permission from
[6])
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Fig. 14. —50-year-old man with hyperparathyroidism. Coronal T1-weighted
MR image (TR/TE, 500/8) shows slightly hyperintense nodule in aortopulmonary
window (arrow), surgically proven to represent parathyroid
adenoma.
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The sensitivity of MR imaging for the detection of hyperfunctioning
parathyroid tissue in patients who were operated on and in those who were not
ranges from 50% to 88% [2,
6].
In conclusion, correct localization of hyperfunctioning parathyroid tissue
improves surgical efficiency but requires familiarity with the imaging
appearances of abnormal parathyroid glands and knowledge of the typical
positions of normally located and ectopic hyperfunctioning parathyroid
tissue.
References
- Satava RM Jr, Beahrs OH, Scholz DA. Success rate of cervical
exploration for hyperparathyroidism. Arch Surg
1975;110:625
-628[Abstract]
- Gotway MB, Higgins CB. MR imaging of the thyroid and parathyroid
glands. Magn Reson Imaging Clin N Am
2000;8:163
-182[Medline]
- Krubsack AJ, Wilson SD, Lawson TL, et al. Prospective comparison of
radionuclide, computed tomographic, sonographic, and magnetic resonance
localization of parathyroid tumors. Surgery
1989;106:639
-644[Medline]
- Moinuddin M, Whynott C. Ectopic parathyroid adenomas: multi-imaging
modalities and its management. Clin Nucl Med
1996;21:27
-32[Medline]
- Neumann DR, Esselstyn CB Jr, Madera AM. Sestamibi/iodine
subtraction single photon emission computed tomography in reoperative
secondary hyperparathyroidism. Surgery
2000;128:22
-28[Medline]
- Gotway MB, Reddy GP, Webb WR, Morita ET, Clark OH, Higgins CB.
Comparison between MR imaging and 99mTc MIBI scintigraphy in the
evaluation of recurrent of persistent hyperparathyroidism.
Radiology
2001;218:783
-790[Abstract/Free Full Text]
- Auffermann W, Guis M, Tavares NJ, Clark OH, Higgins CB. MR signal
intensity of parathyroid adenomas: correlation with histopathology.
AJR
1989;153:873
-876[Abstract/Free Full Text]
- Santos E, Higgins CB, Clark O. Recurrent hyperparathyroidism caused
by a parathyroid cystic adenoma: localization by MRI. J Comput
Assist Tomogr 1996;20:996
-998[Medline]
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