24 Questions
What is the initial effect of inflammation on thyroid hormones in Hashitoxicosis?
Transitory elevation of thyroid hormones
Which imaging modality is superior to CT for assessing invasion of trachea/oesophagus in thyroid cancer?
MRI
What is the characteristic appearance of enlarged parathyroid glands on imaging?
Hypoechoic nodules
What is the primary purpose of contrast-enhanced CT scans in thyroid cancer?
To assess the extension and invasion of tumor into adjacent neck structures
What is the role of Ultrasonography Guided Fine Needle Aspiration (FNA) in thyroid nodules?
To collect a tissue sample for cytological analysis
Which of the following is NOT a type of thyroid nodule?
Parathyroid nodule
What is the role of Scintigraphy in thyroid imaging?
To assess the function of thyroid nodules
Which imaging modality is NOT commonly used in thyroid gland imaging?
X-ray
What is the recommended imaging modality for the thyroid gland?
Ultrasound
What is the characteristic of a Lipid-Poor Adenoma on CT?
Signal drop on out-of-phase imaging
What is the role of fat in differentiating Adenoma from Carcinoma?
Fat is identified in Adenoma to differentiate from Carcinoma
What is the recommended imaging modality for the pituitary gland?
MRI
What is the characteristic of a Parathyroid gland on imaging?
Not identifiable in all imaging modalities
What is the characteristic of Graves' disease on Ultrasound?
Heterogenous, hypermetabolic
What is the characteristic of a Pheochromocytoma on MRI?
High signal on T2W
What is the role of Calcification in Adrenal Gland Pathology?
Coarse calcification is benign
What is the recommended imaging modality for the adrenal gland in neonates and children?
Ultrasound
What is the characteristic of an Adrenal gland on Ultrasound?
Layers of cortex and medulla are identifiable in neonates and young children
What is the typical echogenicity of the thyroid gland in relation to the surrounding strap muscles on ultrasound?
Hyperechoic
What is the normal range of length for the thyroid gland lobes on ultrasound?
4-5 cm
What type of Doppler image is typically used to evaluate thyroid vascularity?
Color Doppler
Which of the following imaging modalities uses ionizing radiation?
X-ray and Computed Tomography (CT)
What is the typical appearance of the thyroid gland on ultrasound in the sagittal plane?
Oval shape
What is the relationship between the thyroid gland and the parathyroid glands in terms of anatomical location?
The parathyroid glands are adjacent to the thyroid gland
Study Notes
Imaging Modalities for Endocrine System
- Imaging modalities for the endocrine system can be categorized into ionizing radiation (X-ray, CT, fluoroscopy, angiography, nuclear medicine) and non-ionizing radiation (US, MRI) methods.
Thyroid and Parathyroids
- The thyroid gland is located in the anterior neck and has a schematic relationship with important anatomical landmarks.
- The parathyroid glands are represented by green dots and are also located in the anterior neck.
Thyroid US Anatomy
- The thyroid gland appears homogenous and echogenic/hyperechoic on US, with a sagittal and axial plane.
- The gland has a normal vascularity on color Doppler image, with a spectral Doppler flow showing a low resistive wave.
- The transverse dimension (width-W) and anterior-posterior length (L) of the lobes are 4-5 cm.
Thyroid Pathology
- Thyroid pathology can be seen in adenoma, myelolipoma, trauma, and granulomatous infection.
- Graves' disease appears as an enlarged, heterogenous, and hypermetabolic gland on imaging.
- Hashimoto's disease cannot be differentiated from Graves' disease on imaging in its initial stage.
Adrenal Gland
- The adrenal gland can be imaged using CT, MRI, and PET-CT.
- A lipid-poor adenoma appears as an indeterminate lesion on non-contrast CT, with a signal drop on out-of-phase imaging compared to in-phase imaging.
- Pheochromocytoma appears as a heterogeneous enhancing right adrenal mass on CT, with intense tracer uptake on PET-CT and a high signal on T2W MRI.
- Adrenocortical carcinoma appears as a heterogeneous enhancing right adrenal mass on CT, with punctate, irregular calcifications.
Take Home Messages
- The first line of imaging modality for endocrine system components depends on the type of organ being imaged.
- Complimentary imaging modalities are used to further evaluate the organ.
- Thyroid gland appears homogenous and echogenic/hyperechoic on US, and hyperdense on CT.
- Parathyroid gland is not identifiable in all imaging modalities when normal, but appears as a hypoechoic nodule when enlarged.
- Pituitary gland is best evaluated using MRI, which can identify microadenoma and macroadenoma.
- Adrenal gland is best evaluated using US in neonates and children, and CT in adults.
Thyroid Nuclear Medicine Studies
- Scintigraphy and PET-CT are used to evaluate thyroid nodules and carcinoma.
- Malignant nodule carcinoma appears as a hot spot on isotope scan/scintigraphy and PET-CT.
Parathyroid Gland Pathologies
- Parathyroid gland pathologies can be seen in adenoma and hyperparathyroidism.
- Enlarged parathyroid glands appear as hypoechoic nodules on US and may compress the adjacent anterior thyroid parenchyma.
FNA and Ultrasound
- Ultrasonography-guided fine needle aspiration (FNA) is used to diagnose thyroid nodules.
- Contrast-enhanced CT scans and MRI are useful in evaluating the extension and invasion of tumor into the adjacent neck structures.
This quiz covers the different imaging modalities used to diagnose and visualize the endocrine system, including the thyroid and parathyroid glands.
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