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Frank P. DawryFrank P. Dawry
Parathyroid Gland ImagingParathyroid Gland Imaging
Frank P. DawryFrank P. Dawry
Physiology of Parathyroid GlandsPhysiology of Parathyroid Glands
Regulation of serum calcium levels via Regulation of serum calcium levels via synthesis and release of parathyroid synthesis and release of parathyroid hormone (PTH)hormone (PTH) Calcium release from bone – increased bone Calcium release from bone – increased bone
breakdown and resorptionbreakdown and resorption Increase in GI tract absorption – increased calcium Increase in GI tract absorption – increased calcium
absorption in the bowelabsorption in the bowel Renal – increased release of serum phosphate levels Renal – increased release of serum phosphate levels
-- -- direct inverse relationship to calcium levelsdirect inverse relationship to calcium levels
Frank P. DawryFrank P. Dawry
HyperparathyroidismHyperparathyroidism
condition of too much parathyroid hormonecondition of too much parathyroid hormone
hyper = too muchhyper = too muchparathyroid = parathyroid hormoneparathyroid = parathyroid hormoneism = a disease or conditionism = a disease or condition
Frank P. DawryFrank P. Dawry
IndicationsIndications In patients with hypercalcemiaIn patients with hypercalcemia
and elevated PTH levelsand elevated PTH levels Locate adenomasLocate adenomas
SingleSingle MultipleMultiple
Identify glandular hyperplasiaIdentify glandular hyperplasia Shorten the operating time during Shorten the operating time during
surgerysurgery Finding hidden parathyroid glands Finding hidden parathyroid glands
– minimize exploration– minimize exploration
ContraindicationsContraindications Patient on calcium Patient on calcium
medicationsmedications Patient on thyroid Patient on thyroid
medicationsmedications
Frank P. DawryFrank P. Dawry
AnatomyAnatomy
Frank P. DawryFrank P. Dawry
RadiopharmaceuticalsRadiopharmaceuticals Tc-99m PertechnetateTc-99m Pertechnetate
Active transport into normal thyroid tissueActive transport into normal thyroid tissue Tl-201 Thallous chlorideTl-201 Thallous chloride
Behaves similar to potassium Behaves similar to potassium Na/K pumpNa/K pump Enters thyroid and parathyroid tissue with blood flowEnters thyroid and parathyroid tissue with blood flow
Tc-99m Sestamibi (Cardiolite)Tc-99m Sestamibi (Cardiolite) Passive transport into thyroid and parathyroid tissue in Passive transport into thyroid and parathyroid tissue in
proportion to blood flowproportion to blood flow Remains longer in adenomas and hyperplastic tissueRemains longer in adenomas and hyperplastic tissue
Tc-99m Tetrofosmin (Myoview) Tc-99m Tetrofosmin (Myoview) Passive transport into thyroid and parathyroid tissue in Passive transport into thyroid and parathyroid tissue in
proportion to blood flowproportion to blood flow Remains longer in adenomas and hyperplastic tissueRemains longer in adenomas and hyperplastic tissue
Frank P. DawryFrank P. Dawry
Adult Dose RangeAdult Dose Range
Tc-99m PertechnetateTc-99m Pertechnetate 5.0 – 12.0 mCi (185-444 MBq)5.0 – 12.0 mCi (185-444 MBq)
Tl-201 Thallous chlorideTl-201 Thallous chloride 2.0-3.0 mCi (74-111 MBq)2.0-3.0 mCi (74-111 MBq)
Tc-99m Sestamibi (Cardiolite)Tc-99m Sestamibi (Cardiolite) 16.0-30.0 mCi (592-1110 MBq)16.0-30.0 mCi (592-1110 MBq)
Tc-99m Tetrofosmin (Myoview) Tc-99m Tetrofosmin (Myoview) 16.0-30.0 mCi (592-1110 MBq)16.0-30.0 mCi (592-1110 MBq)
I-123I-123 270 uCi (10 MBq)270 uCi (10 MBq)
Frank P. DawryFrank P. Dawry
EquipmentEquipment
LFOV cameraLFOV cameraPinhole and/or LEHRPinhole and/or LEHRPlanarPlanar
128x128 matrix128x128 matrix1.0 million counts or 300-900 seconds/frame1.0 million counts or 300-900 seconds/frame
SPECTSPECT360 degrees360 degrees128x128 matrix128x128 matrix20-25 seconds/stop20-25 seconds/stop
Frank P. DawryFrank P. Dawry
ProcedureProcedure
Dual-Isotope SubtractionDual-Isotope Subtraction
TechniqueTechnique Tl-201/Tc-99m – inferiorTl-201/Tc-99m – inferior Tc-99m/Cardiolite – superiorTc-99m/Cardiolite – superior Tc-99m/Myoview – little Tc-99m/Myoview – little
published datapublished data I-123/Cardiolite – superiorI-123/Cardiolite – superior I-123/Myoview – little I-123/Myoview – little
published datapublished data
Single-Nuclide Two-Phase Single-Nuclide Two-Phase (thyroid phase, (thyroid phase,
parathyroid phase)parathyroid phase) Tc-99m CardioliteTc-99m Cardiolite
Frank P. DawryFrank P. Dawry
Dual-Isotope SubtractionDual-Isotope SubtractionTechnique Technique
VariationVariation Administer I-123Administer I-123 Wait 2-4 hoursWait 2-4 hours Acquire 300 second acquisition using a pinhole Acquire 300 second acquisition using a pinhole
collimator at 159 keV settingcollimator at 159 keV setting Without moving the patient, inject ~15 mCi of CardioliteWithout moving the patient, inject ~15 mCi of Cardiolite Wait 5 minutesWait 5 minutes Acquire 300 second acquisition at 140 keV setting.Acquire 300 second acquisition at 140 keV setting.
Possible to acquire both images at the same time using Possible to acquire both images at the same time using asymmetric windowingasymmetric windowing
Frank P. DawryFrank P. Dawry
ProcessingProcessing
Normalize I-123 to thyroid counts in Tc-Normalize I-123 to thyroid counts in Tc-99m Cardiolite image99m Cardiolite image
Subtract normalized I-123 image from Tc-Subtract normalized I-123 image from Tc-99m Cardiolite image99m Cardiolite image
Positive = tissue remainingPositive = tissue remaining
Frank P. DawryFrank P. Dawry
Draw ROI and obtain total counts in ROI
Raw I-123 image
Copy ROI to Sestamibi Image and obtain total counts in ROI
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
Parathyroid
Frank P. DawryFrank P. Dawry
Frank P. DawryFrank P. Dawry
Single-Nuclide Two-Phase Single-Nuclide Two-Phase (thyroid phase, parathyroid phase)(thyroid phase, parathyroid phase)
TechniqueTechnique
Inject Tc-99m CardioliteInject Tc-99m Cardiolite Wait 10 minutesWait 10 minutes Acquire 300 second image of anterior neck Acquire 300 second image of anterior neck
using LEHR, 128x128 matrixusing LEHR, 128x128 matrix Acquire a planar static image again at 1 and 2 Acquire a planar static image again at 1 and 2
hours laterhours later
Positive = slower washout structures within the Positive = slower washout structures within the imageimage
Frank P. DawryFrank P. Dawry
Frank P. DawryFrank P. Dawry
Combination of Combination of Dual-Isotope Dual-Isotope SubtractionSubtraction
Technique Technique andand Single-Nuclide Two-Single-Nuclide Two-Phase Phase TechniqueTechnique
Perform the Dual-Isotope SubtractionPerform the Dual-Isotope SubtractionTechnique and have patient return 1 to 2 Technique and have patient return 1 to 2 hours later to image the Sestamibi nuclide hours later to image the Sestamibi nuclide as in the as in the Two-Phase Two-Phase Technique.Technique.
Frank P. DawryFrank P. Dawry
SPECT/CTSPECT/CT