Endocrine Imaging Flashcards
(38 cards)
What is the most common type of functional pituitary adenoma?
Prolactinoma
What imaging modality is preferred for pituitary pathology?
MRI
What are the contents of the dural venous sinus through which the ICA passes?
CNIII, CNIV, CNVI, CNV1, CNV2 (superior to inferior), ICA with sympathetic plexus
What is the anatomical mechanism underlying bitemporal hemianopia in pituitary adenoma?
Compression of the optic chiasm by an enlarged pituitary gland
Which multiple endocrine neoplasia (MEN) syndrome do pituitary tumours occur in?
MEN1- parathyroid tumours, Pancreatic Neuroendocrine Tumors (pNET),
pituitary tumours
Describe the pathology demonstrated in the MRI study.
Enlarged pituitary gland.
Why is the sphenoid sinus important in transsphenoidal hypophysectomy?
Because it provides a direct surgical corridor to the pituitary gland, allowing access without opening the skull or retracting brain tissue.
Q: What are the typical imaging features of a multinodular goitre?
Enlarged thyroid with multiple nodules of varying size and echogenicity.
What is the difference between toxic and non-toxic multinodular goitre?
Toxic: TSH-independent hormone production; Non-toxic: euthyroid.
What is the relation of the carotid sheath to the thyroid?
Carotid sheath lies posteriolateral to the lobes of the thyroid
What are the contents of the carotid sheath?
Common carotid artery (A), internal
jugular vein (B), vagus nerve (C)
Which follow-up imaging study would characterise the functional status of the nodule?
Thyroid scintigraphy
Tc99m pertechnetate is administered IV, images captured with scintillation camera.
Pertechnetate behaves similarly to iodine.
What are the expected TSH and T3/T4 levels in patients with Graves disease, multinodular goitre, or autonomous nodule?
Low TSH, High T3/T4
What are key ultrasound features that raise suspicion for thyroid malignancy?
Microcalcifications, irregular margins, hypoechogenicity, loss of pseudocapsule.
The findings pre biopsy are highly suspicious for thyroid
malignancy. If the pseudocapsule disappears and you lose the
interface between the lesion and the normal parenchyma, be
careful. The presence of microcalcifications is a second
indication for FNA. This is a confirmed papillary carcinoma of
the thyroid.
What are the major types of primary thyroid cancers?
Papillary, follicular, medullary, anaplastic
Why are microcalcifications concerning on thyroid ultrasound?
They are associated with papillary thyroid carcinoma.
Which thyroid malignancy subtype is the most common?
Papillary thyroid carcinoma.
What are the risk factors for thyroid malignancy?
Head and neck irradiation, family history, age <30 or >60, male, >2 cm nodule
How does the functional status of a thyroid nodule affect management?
Functioning (hot) nodules are often benign; non-functioning (cold) nodules may need biopsy.
What is a tumour of the chromaffin cells in the adrenal medulla called?
Phaeochromocytoma
What is the function of chromaffin cells?
Release catecholamines (epinephrine/norepinephrine) from adrenal medulla.
What imaging modalities are relevant for adrenal pathology?
MRI, MIBG scan
MIBG - Metaiodobenzylguanidine
How does MIBG uptake help differentiate adrenal masses?
It confirms catecholamine-producing tumors like pheochromocytoma.
MIBG (Metaiodobenzylguanidine) is a radiolabeled molecule similar to norepinephrine. It is taken up by chromaffin cells in the adrenal medulla, which are the cells involved in phaeochromocytoma.
When injected intravenously, MIBG is absorbed by these cells. Because phaeochromocytomas actively take up norepinephrine, they accumulate the MIBG tracer. A gamma camera then detects this uptake on a scan, highlighting the tumor.
Key Point:
Phaeochromocytomas appear as areas of increased uptake on the MIBG scan, helping localize and confirm the diagnosis, even if the tumor is extra-adrenal or metastatic.
