Transcript Parathyroid Gland Imaging Frank P. Dawry Physiology of Parathyroid Glands  Regulation of serum calcium levels via synthesis and release of parathyroid hormone (PTH)    Calcium release from.

Parathyroid Gland Imaging
Frank P. Dawry
Physiology of Parathyroid Glands
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Regulation of serum calcium levels via
synthesis and release of parathyroid
hormone (PTH)
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Calcium release from bone – increased bone
breakdown and resorption
Increase in GI tract absorption – increased calcium
absorption in the bowel
Renal – increased release of serum phosphate levels
-- direct inverse relationship to calcium levels
Frank P. Dawry
Hyperparathyroidism
condition of too much parathyroid hormone
hyper = too much
parathyroid = parathyroid hormone
ism = a disease or condition
Frank P. Dawry
Indications
Contraindications
In patients with hypercalcemia
and elevated PTH levels
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Locate adenomas
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Single
Multiple
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Patient on calcium
medications
Patient on thyroid
medications
Identify glandular hyperplasia
Shorten the operating time during
surgery
Finding hidden parathyroid glands –
minimize exploration
Frank P. Dawry
Anatomy
Frank P. Dawry
Radiopharmaceuticals
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Tc-99m Pertechnetate
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Tl-201 Thallous chloride
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Behaves similar to potassium
Na/K pump
Enters thyroid and parathyroid tissue with blood flow
Tc-99m Sestamibi (Cardiolite)
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Active transport into normal thyroid tissue
Passive transport into thyroid and parathyroid tissue in
proportion to blood flow
Remains longer in adenomas and hyperplastic tissue
Tc-99m Tetrofosmin (Myoview)
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Passive transport into thyroid and parathyroid tissue in
proportion to blood flow
Remains longer in adenomas and hyperplastic tissue
Frank P. Dawry
Adult Dose Range
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Tc-99m Pertechnetate
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Tl-201 Thallous chloride
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16.0-30.0 mCi (592-1110 MBq)
Tc-99m Tetrofosmin (Myoview)
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2.0-3.0 mCi (74-111 MBq)
Tc-99m Sestamibi (Cardiolite)
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5.0 – 12.0 mCi (185-444 MBq)
16.0-30.0 mCi (592-1110 MBq)
I-123
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270 uCi (10 MBq)
Frank P. Dawry
Equipment
LFOV camera
 Pinhole and/or LEHR
 Planar
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128x128 matrix
 1.0 million counts or 300-900 seconds/frame
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SPECT
360 degrees
 128x128 matrix
 20-25 seconds/stop
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Frank P. Dawry
Procedure
Dual-Isotope Subtraction
Technique
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Tl-201/Tc-99m – inferior
Tc-99m/Cardiolite – superior
Tc-99m/Myoview – little
published data
I-123/Cardiolite – superior
I-123/Myoview – little
published data
Single-Nuclide Two-Phase
(thyroid phase,
parathyroid phase)
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Tc-99m Cardiolite
Frank P. Dawry
Dual-Isotope Subtraction
Technique
Variation
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Administer I-123
Wait 2-4 hours
Acquire 300 second acquisition using a pinhole
collimator at 159 keV setting
Without moving the patient, inject ~15 mCi of Cardiolite
Wait 5 minutes
Acquire 300 second acquisition at 140 keV setting.
Possible to acquire both images at the same time using
asymmetric windowing
Frank P. Dawry
Processing
Normalize I-123 to thyroid counts in Tc99m Cardiolite image
 Subtract normalized I-123 image from Tc99m Cardiolite image
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Positive = tissue remaining
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Raw I-123
image
Draw ROI and obtain total
counts in ROI
Copy ROI to Sestamibi Image
and obtain total counts in ROI
Parathyroid
Normalized I-123 Image
multiply the Raw I-123 image counts
by the ratio of
I-123 ROI counts/Sestamibi ROI
counts
Subtracted Image
Subtract normalized I-123 image
from the Sestamibi image
Frank P. Dawry
Frank P. Dawry
Single-Nuclide Two-Phase
(thyroid phase, parathyroid phase)
Technique
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Inject Tc-99m Cardiolite
Wait 10 minutes
Acquire 300 second image of anterior neck
using LEHR, 128x128 matrix
Acquire a planar static image again at 1 and 2
hours later
Positive = slower washout structures within the
image
Frank P. Dawry
Frank P. Dawry
Combination of Dual-Isotope
Subtraction
Technique and Single-Nuclide TwoPhase Technique
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Perform the Dual-Isotope Subtraction
Technique and have patient return 1 to 2
hours later to image the Sestamibi nuclide
as in the Two-Phase Technique.
Frank P. Dawry
SPECT/CT
Frank P. Dawry