Radiology Board Review Quiz

Differentiation of Graves disease (uptake high, usually >35% at 24 hours) from subacute or factitious hyperthyroidism (uptake usually < 2%). Calculation of radioactive iodine dose for treatment of Graves disease. Assessment of suspected toxic multinodular goiters.

Descending transtentorial herniation, also known as uncal herniation, is characterized by effacement of suprasellar and perimesencephalic cisterns, with inferior displacement of pineal calcification. Look for compression of the ipsilateral third cranial nerve and potential contralateral cerebral peduncle compression (Kernohan's notch). Ascending transtentorial herniation involves upward displacement of the cerebellar vermis and hemispheres, often due to large posterior fossa masses or hematomas. Be cautious of mimickers like brainstem tumors or severe hydrocephalus that can alter cisternal anatomy.

Connect alveoli with respiratory, terminal, and preterminal bronchioles.

Spinal cord ependymomas are the most common intramedullary spinal cord tumors in adults, with a peak incidence in the fourth decade and a male predominance. They are categorized into cellular (intramedullary) and myxopapillary (filum terminale) types. On MRI, they typically show low T1 and high T2 signal with variable enhancement, often with a characteristic 'cap sign' of hemosiderin at the poles. They may mimic astrocytomas but are more likely to be well-circumscribed and have a central location. Increased incidence is seen in patients with neurofibromatosis type 2. A common pitfall is confusing them with metastatic lesions, which usually have more irregular enhancement patterns.

Transudative. Bilateral, right larger than left. Isolated right effusion twice as common as isolated left effusion.

Form of peripheral lobar atelectasis that develops with pleural disease (commonly asbestosis). Volume loss. Comet tail (whorled bronchovascular structures).

Metastases often present as multiple lesions with significant edema and ring enhancement. Abscesses typically show restricted diffusion on DWI and may have a central necrotic core. Glioblastoma multiforme (GBM) is characterized by an irregular ring-enhancing mass with central necrosis and can cross the corpus callosum. Radiation necrosis can mimic tumor recurrence but often shows less enhancement and increased T2/FLAIR signal. Hematomas may show a fluid-fluid level and evolve over time. Be cautious of mimickers like tumefactive demyelination, which can also present with edema and ring enhancement.

Idiopathic pulmonary fibrosis.  Sarcoidosis.  Eosinophilic granuloma.  Rheumatoid lung.  Scleroderma.  Pneumoconiosis.  Hypersensitivity pneumonitis.  Chronic aspiration.  Radiation fibrosis.

Mucous retention cyst: Appears as a well-defined, round, non-expansile lesion within the sinus, typically less than 2 cm, and does not cause bone remodeling. Mucocele: Results from complete obstruction of the sinus ostium, leading to expansile growth, sinus wall thinning, and potential bone remodeling. Key diagnostic features include expansion and thinning of the sinus walls on imaging. Clinical pearls: Mucoceles can cause significant symptoms due to pressure effects, while retention cysts are often incidental findings. Common pitfalls include mistaking a retention cyst for a polyp or small mucocele; careful assessment of bone involvement can aid differentiation.

Cisternogram.