#ctrad

Here's a companion case to yesterday's. This is a neonate with respiratory distress.

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The right mid to lower lung is hyperinflated. There is leftward medisastinal shift, including prominent medisatinal fat (that's not a mass in the left lung). CT shows cystic expansion of the right lung (2nd image). This is a congenital pulmonary airway malformation (CPAM) formerly known as congenital cystic airway malformation (CCAM). CPAM is a multicystic mass with abnormal bronchial proliferation. Differential diagnosis includes pulmonary sequestration, congenital lobar overinflation, and bronchogenic cyst (usually not aerated).

The differential diagnosis of a middle mediastinal mass includes lymph nodes, foregut duplication cysts, tracheal/bronchial lesions, lipoma, esophageal lesions (benign or malignant) and vascular lesions (aortic aneurysm, varices).

This case is a 70-year-old man who presented with cough and hemoptysis. Chest radiograph reveals a right mediastinal mass that silhouettes the right hilar vessels, localizing the lesion to the middle mediastinum. There is also mass effect on the trachea and widening of the right paratracheal stripe. CT reveals a mass along the right tracheal border, which also encases the right mainstem bronchus. Biopsy revealed small cell bronchial carcinoma.

Imaging of autosomal dominant polycystic kidney disease (ADPKD) can be done via US, CT, or MRI. The dominant feature is innumerable large cysts in the kidneys. Large liver cysts are also common, and cysts can be seen in various other organs as well, including pancreas, spleen, ovaries, seminal vesicles, and prostate. Unlike ARPKD, the kidneys are normal at birth and develop cysts later.

Despite the impressive appearance of these cysts, there is no increased risk of renal cell carcinoma in ADPKD. Patients can also be imaged with CTA or MRA of the head to screen for intracranial aneurysms, found in 16% of patients with ADPKD and family history.

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.

Less than 0.01% of intervascular dose of iodinated contrast and less than 0.0004% of Gd-based contrast is absorbed from the GI tract of the child, far less than the permissible dose of IV contrast in neonates. Theoretical risks to the child are direct toxicity and allergic sensitization or reaction, but these have not been reported.