Prostate cancer is the second most common cancer in men worldwide, with a wide spectrum of biologic behavior ranging from indolent low-risk disease to highly aggressive castration-resistant prostate cancer. Conventional imaging with computed tomography, magnetic resonance imaging, and bone scintigraphy is limited for the detection of nodal disease and distant bone metastases. In addition, advances in the available therapeutic options, both localized and systemic, drive the requirement for precise diagnostic and prognostic tools to refine the individual therapeutic approach at various times in the management of patients with prostate cancer. Positron emission tomography (PET) has a rapidly evolving role in the assessment of prostate cancer, particularly in the scenario of biochemical relapse. Fluorine 18 (F) fluorodeoxyglucose, the most widely available PET tracer, has limitations, particularly in indolent prostate cancer. In the past decade, several PET tracers with specific molecular targets have reached the clinical domain. These tracers include F-sodium fluoride, which is a bone-specific biomarker of osteoblastic activity;F-choline and carbon 11-choline, which are directed at cell membrane metabolism; gallium 68-prostate-specific membrane antigen ligands; and, more recently, an amino acid analog, F-fluciclovine (anti-1-amino-3-F-fluorocyclobutane-1-carboxylic acid; also known as FACBC), which is also directed at cell membrane turnover. The mechanisms of actions of the clinically available PET tracers are reviewed, as well as their role in the imaging of prostate cancer with reference to relevant guidelines and the technical and imaging pearls and pitfalls of these tracers. RSNA, 2017.

A number of mediastinal reflections are visible at conventional radiography that represent points of contact between the mediastinum and adjacent lung. The presence or distortion of these reflections is the key to the detection and interpretation of mediastinal abnormalities. Anterior mediastinal masses can be identified when the hilum overlay sign is present and the posterior mediastinal lines are preserved. Widening of the right paratracheal stripe and convexity relative to the aortopulmonary window reflection indicate a middle mediastinal abnormality. Disruption of the azygoesophageal recess can result from disease in either the middle or posterior mediastinum. Paravertebral masses disrupt the paraspinal lines, and the location of masses above the level of the clavicles can be inferred by their lateral margins, which are sharp in posterior masses but not in anterior masses. The divisions of the mediastinum are not absolute; however, referring to the local anatomy of the mediastinal reflections in an attempt to more accurately localize an abnormality may help narrow the differential diagnosis. Identification of the involved mediastinal compartment helps determine which imaging modality might be appropriate for further study.

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Improvements in imaging technology allow exploitation of the dual blood supply of the liver to aid in the identification and characterisation of both malignant and benign liver lesions. Imaging techniques available include contrast enhanced ultrasound, computed tomography and magnetic resonance imaging. This review discusses the application of several imaging techniques in the diagnosis and staging of both hepatocellular carcinoma and cholangiocarcinoma and outlines certain characteristics of benign liver lesions. The advantages of each imaging technique are highlighted, while underscoring the potential pitfalls and limitations of each imaging modality.