The hip has multiple anatomic variants that can mimic abnormalities at hip MRI. The labrum has several anatomic variants that can be confused with true labral tears.

BackgroundPulmonary arteries are not just affected by thrombus. Congenital and acquired conditions can also involve the pulmonary arteries. An awareness of these conditions is important for the radiologist interpreting chest computed tomography (CT).MethodsThe anatomy of the pulmonary arteries was reviewed. CT and magnetic resonance (MR) acquisition protocols for imaging the pulmonary arteries were discussed. The imaging appearances of congenital and acquired anomalies involving the pulmonary arteries, using CT and other modalities, were presented.ResultsImaging features of congenital anomalies presented include pulmonary agenesis, partial pulmonary artery agenesis, patent ductus arteriosus, pulmonary artery sling, congenital pulmonary artery stenosis and coronary to pulmonary artery fistula. Acquired pulmonary artery anomalies discussed include arteritis, infected aneurysm and sarcoma. Pulmonary artery filling defects besides thromboembolism are also discussed, including foreign body emboli. Imaging features of bronchogenic carcinoma and mediastinal fibrosis demonstrating compression of the pulmonary arteries are presented, followed by a brief discussion of post repair appearance of the pulmonary arteries for congenital heart disease.ConclusionsCongenital and acquired pulmonary artery anomalies have a characteristic appearance on a variety of imaging modalities. An acquaintance with the imaging features of these anomalies is needed to avoid misinterpretation and reach the correct diagnosis.Teaching Points• Discuss a variety of congenital and acquired anomalies of the pulmonary arteries.• Discuss the imaging appearance of the presented congenital or acquired pulmonary artery anomalies.• Describe CT and MR acquisition protocols for imaging the pulmonary arteries.• Review the anatomy of the pulmonary arteries.

The hip has multiple anatomic variants that may mimic disease on hip MRI. Like labral variants, nonlabral variants can be confused for true abnormalities.

Metastases to the thyroid gland are uncommon. We present the sonographic features of metastatic breast adenocarcinoma to the thyroid in a 67-year-old woman. The lesion measured up to 0.9 cm in diameter, contained an echogenic focus with associated ring-down, and was predominantly cystic, thereby resembling a benign nodule. Because of the patient's history of breast adenocarcinoma, the nodule nevertheless underwent fine-needle aspiration. The unusual appearance of the thyroid nodule underscores the importance of considering patient history in deciding whether obtaining tissue diagnosis of thyroid nodules is warranted.

A 55-year-old man with end-stage liver disease status post transjugular intrahepatic portosystemic shunt procedure presents for routine sonographic evaluation for transjugular intrahepatic portosystemic shunt patency. FIGURE 3. T2-weighted (A) and T1-weighted (B) fat-saturated axial MRI scans. The cystic spaces of Rokitansky-Aschoff sinuses (solid arrow) are clearly demonstrated on MRI, and they have high T2 and low T1 signal and exhibit a characteristic ''pearl necklace'' sign. Furthermore, the gallbladder wall (broken arrow) enhances, whereas cystic spaces do not on the postcontrast T1-weighted fat saturated axial MRI scan (C).