CME Sessions at EANM’05

EANM’05 – CME Session I

Endocrinology
October 16, 2005, 08:00 – 09:30
Nuclear Medicine in Endocrine Diseases

Moderator: R.P. Baum (Bad Berka)
CoModerator: P. Lind (Klagenfurt)


Speakers:
extended
abstract
I. Igerc (Klagenfurt):
The role of NM in thyroid and parathyroid diseases
A. Kurtaran (Vienna):
The role of NM in adrenal gland diseases
R.P. Baum (Bad Berka):
The role of NM in NET


Educational objectives:

Upon completion of this course the attendee will be able to:

  1. understand the principles of diagnosing endocrine diseases (thyroid, parathyroid, adrenal gland, neuroendocrine tumors)
  2. to know the possibilities, methodology and clinical value of nuclear medicine imaging in endocrine diseases including thyroid, parathyroid, adrenal gland imaging and imaging in neuroendocrine tumors (NET)
  3. to understand the role of nuclear medicine imaging in the diagnosis of thyroid and parathyroid diseases, including thyroid ultrasonograpy, Tc-99m pertechnetate and I-123 scintigraphy, parathyroid Tc-99m pertechnetate (I-123)/Tc-99m Sestamibi (Tetrofosmin) subtraction scintigraphy and SPECT
  4. to understand the significant role of nuclear medicine imaging in the routine clinical work-up of adrenal diseases on the basis of clinical examples
  5. to understand the main indications for adrenal scintigraphy, SPECT/PET radiopharmaceuticals, the routine study protocols and to identify and avoid the pitfalls in adrenal scintigraphy
  6. to understand the possibilities and principles of peptide receptor radiotherapy in adrenal gland disease
  7. to understand the role of nuclear medicine imaging in NET including In-111 and Tc-99m labelled radiopharmaceuticals as well as FDG and different somatostatin analogs labeled with Ga-68 used for PET and PET/CT
  8. to understand the possibilities and principles of peptide receptor radiotherapy in NET

 


Summary:

Nuclear medicine plays an importatnt role in diagnosing thyroid diseases. Especially in case of proven hyperthyroidism Tc-99m or I-123 scintigraphy is able to differentiate between destructive and productive etiology of the disease and to differentiate between Graves disease and thyroid autonomy. Although ultrasonography guided FNAB is the method of choice in case of hypoechogenic nodules, functional scintigraphy is part of the work up of thyroid nodules to evaluate possible malignancy. In the era of minimal invasive surgery parathyroid imaging again has become important for localizing adenomas. Today Tc-99m pertechnetate (I-123)/Tc-99mSestamibi (Tetrofosmin) subtraction scintigraphiy and SPECT in combination with high resolution ultrasonography is the standard investigation to localize adenomas. In endemic goiter areas false positive results are frequent due to thyroid nodules.

Scintigraphic imaging of the adrenal glands performed with iodone labeled SPECT/PET radiopharmaceuticals provides specific metabolic information, thus complementing morphological (anatomical) imaging techniques. In case of biochemically confirmed hormone-active adrenal diseases the clinician needs to address the question whether one or both adrenal glands are involved. In patients having non-secretory adrenal masses which are mostly discovered incidentally (incidentaloma) attention must be paid to distinguish benign from malignant lesions. Once malignancy has been proven, further diagnostic work-up has to be undertaken for the evaluation of regional and distant metastatic spread as a part of clinical staging. This underlines the necessity for a whole body study which can be provided by scintigraphy.

Adrenocortical scintigraphy with radiolabeled cholesterol (I131-6 beta-iodomethyl-19-nor-cholesterol)

  • Differential diagnosis between adrenocortical adenoma and bilateral hyperplasia (with and without dexamethason suppression)
  • Characterization of non-functioning adrenocortical malignancies (adrenocortical carcinoma and adrenal metastases)

Adrenomedullary imaging with iodine labeled MIBG (Meta-Iodobenzylguanidine scintigraphy)

  • Non-invasive and safe localization of pheochromocytomas/ paragangliomas
  • Characterization of an incidentally detected adrenal lesion
  • Differentiation of unilateral or bilateral disease.
  • Localization of distant lesions in case of malignant pheochromocytomas/ paragangliomas

PET imaging with 18F-FDG, 18F-DOPA, C11- MetomidatePET imaging with 18F-FDG, 18F-DOPA, C11- Metomidate

  • Detection of primary and malignant adrenal lesions
  • Distinguishing adrenocortical and non-cortical lesions
  • Discriminating between benign and malignant lesions

Somatostatin receptor scintigraphy (SMRS) specifically detects neuroendocrine tumors (NET) and receptor positive metastases with high sensitivity (80 to > 95 %) and allows a whole-body diagnosis by one scintigraphic examination. Even small primary tumors and metastases, which are difficult to diagnose by CT, MRI or sonography, can be detected if the receptor density is high. If there is strong suspicion of a GEP tumor, or if a NET has been proven by immunohistochemistry, SMRS should be the first diagnostic procedure for staging (before CT and MRI). Further indications are the follow-up after operation and the diagnosis of recurrences in case of increasing specific tumor markers. The radiolabeling of specific peptides which bind to somatostatin receptors on neuroendocrine tumors, enables an internal radionuclide therapy at low radiation risk for normal tissues (there is only a significant radiation burden to the kidneys and too a much lesser extent of the bone marrow) which can be repeatedly performed with little harm to the patient. Especially those patients with slowly growing hepatic and extrahepatic metastases (which are a poor target for chemotherapy) and those, where all surgical options have been used, are good candidates for peptide receptor radiotherapy (PRRT). Also patients who are progressing under octreotide therapy or under combined biotherapy and those with persisting symptoms (diarrhoea, flush) despite high dose hormonal therapy are suitable for peptide receptor radiotherapy. The results obtained in several European oncology centers as well as of multicenter trials, show a promising tumor response rate and a significant improvement of clinical symptoms after PRRT.


Key Words:

  1. Tc-99m pertechnetate scintigraphy
  2. ultrasonography and us-guided FNAB
  3. Tc-99m Sestamimi/Tetrofosmon subtracion scintigraphy and SPECT in parathyroid imaging
  4. I131-6-beta-iodomethyl-19-nor-cholesterol(NP59)scintigraphy
  5. Iodine-123-Meta-Iodobenzylguanidine scintigraphy
  6. 18F-FDG/18F-DOPA/11C-Metomidate PET
  7. Neuroendocrine tumors
  8. somatostatin receptor scintigraphy
  9. PET/CT
  10. Ga-68 labelling of peptides
  11. peptide receptor radiotherapy (PRRT)
  12. dosimetry
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