how to use the gamma camera in diagnosing a parathyroid lesion ?! and which tracer should you use ??

1. {
Radionuclide imaging
of parathyroid glands
By
Eman sultan
Passant dorgham

2. Stimulates the
gland to
secrete PTH
Increase ca mobility
from bones
(osteoclastic
stimulation )
Kidney
- Resorb ca
- Increase
Activation
of vit. D
Why parathyroid glands ??

3. What is parathyroid gland ?
Embryology & Anatomy
Develop at 6 weeks and
migrate caudally at 8 weeks
The paired superior parathyroid
glands develop with the thyroid gland
from the 4th branchial pouch .. Then
migrate to coricothyroid cartilage level
.. Lateral &posterior to the upper pole
thyroid
The paired inferior parathyroid
glands develop with the thymus from
the 3rd branchial pouch the n migrate
to the level of aortic arch or fail to
migrate

4. What is parathyroid gland ?
anatomy
Parathyroid glands usually
eembeded between the posterior
border of the thyroid gland and
its fibrous capsule
Each one measures 6 x 4 x 2
mm and weigh 25-40mg
The number of the glands vary from
2 – 6

5. Blood supply :
Branches from the inferior & superior thyroid arterys
Venous drainage :
to the superior , middle , inferior thyroid veins
What is parathyroid gland ?
anatomy

6. Ectopic locations of the parathyroid
gland
• Para-eosophageal
• Intra-thymic
• Thyro-thymic ligament
• Intrathyroid
• Carotid sheath
• Undescended ( high cervical )/
retropharyngeal
• Mediastinal

7. • Adenoma
• Hyperplasia
• Carcinoma
primary
• Hyperplasia
(chronic renal
failure,
malabsorption)
Secondary
• Autonomous
secondary
(renal
transplant pt )
Tertiary
Hyperparathyroidism –
pathophysiology

8. Parathyroid scintigraphy protocol

9. Dual phase planar imaging
Thyroid &parathyroid glands
imaged at 15 min and 2
hours after tracer injection
Tracers :
1. TC99m MIBI
2. TC99m TETR
MIBI clears from thyroid with
half life 30 min but retained
by the abnormal parathyroid
glands … unlike TETR which
clear much slowly from
thyroid

10.  According to the “
differential washout”
targeted to the back ground
activity , the abnormal
parathyroid tissue become
more evident on delayed
images

11.  Dual isotope imaging sometimes used with
dual phase imaging especially with history of
thyroid disease or surgery
 This type compares pattern of TC99m MIBI
or TETR localization to thyroid specific
radiopharmaceutical to evaluate
concordance (related to thyroid tissue )
versus discordance (indicative of parathyroid
tissue ) called subtraction method .
Dual isotope imaging

12. Parathyroid scintigraphy
90% sensitive for localizing
adenomas but 60% sensitive
for hyperplasia .

13. SPECT (Single-photon emission
computed tomography)
• To enlarge the gland
• See the adenoma not seen on planar images
• To confirm diagnosis & Define the position precisely
• Thyroid adenoma or carcinoma can coexist and can
retain tracer resulting in false positive study

14. Scintigraphy- reporting
• patient indication for the
study
• Procedure
- radiopharmaceuticals
- timing of acquisition of
images
- planar or SPECT
- time of detection of the
lesion
- definite location of the lesion
• Study limitation (paatient
movements)
• Interpretation & computer
subtraction