#usrad

Autosomal recessive polycystic kidney disease (ARPKD) is often first suspected at prenatal or neonatal ultrasound. Imaging features include enlarged, echogenic kidneys, with poor corticomedullary differentiation, often without discretely discernible cysts. If a linear (high frequency) probe is used, small tubular cysts can be seen, which are the ectatic collecting ducts.

Hepatic fibrosis and biliary abnormalities are associated with ARPKD, and these can also be seen on ultrasound. In patients with severe hepatic fibrosis, splenomegaly and portosystemic varices may also be present.

A: It’s unique for each modality, as follows:

For CT and MR, the well-known VINDICATE mnemonic can guide you: Studies to assess for Vascular, infectious, neoplastic, autoimmune, and endocrine/metabolic disorders are usually performed with contrast (except CT for pneumonia). Studies for degenerative and/or traumatic injuries are usually without contrast (except trauma “pan scans” or similar studies). Iatrogenic and congenital can go either way.

Contrast-enhance ultrasound can assess liver and kidney lesions but should be ordered in consultation with a radiologist.

Thyroid ultrasound and nuclear thyroid scintingraphy are complementary methods for evaluation of thyroid nodules, hyperthyroidism, or hypothyroidism.

Today we'll focus on ultrasound of the thyroid gland. The most common indications for thyroid ultrasound are for the evaluation of a palpable nodule or a nodule detected incidentally on another imaging modality. Patients with hyperthyroidism may undergo ultrasound to assess for the presence of nodules. Biopsy recommendations for nodules are made by the radiologist based on TI-RADS criteria (these are too boring to cover here...no really).

Case: Hashimoto's thyroiditis. Grayscale and color Doppler images show a typical appearance of thyroiditis, with a heterogeneous, hypervascular gland (clinical history and serology are needed to establish the diagnosis).

Patients with impaired renal function or pediatric patients (to avoid ionizing radiation) can have their kidneys imaged with contrast-enhanced ultrasound (CEUS). This uses intravenous microbubbles that reflect sound waves.

Today's case is an interesting use of CEUS in a 15 year-old girl who fell from a horse and sustained a grade IV renal and splenic injury. 3 months later, follow-up imaging with CEUS was performed, showing a non-enhancing area in the left kidney but otherwise normally enhancing kidney, and a homogenously enhancing, intact spleen (second image). Grayscale images are shown next to the CEUS images for comparison.