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Concentric target sign (cerebral toxoplasmosis)

The concentric target sign is a typical sign for cerebral toxoplasmosis. It is seen on T2 weighted MR imaging as a deep parenchymal lesion showing a series of concentric rings with hyperintense and hypointense/isointense signal alternatingly. Strong perifocal edema is usually visible on T2/FLAIR...

H-shaped vertebra

H-shaped vertebrae, also known as Lincoln log vertebrae, are a characteristic finding of sharply delimited central endplate depression, classically seen in approximately 10% of patients with sickle-cell anemia, and results from microvascular endplate infarction (figure 1) 3. It may occasionally...

Low attenuation lymphadenopathy

Low attenuation lymphadenopathy suggests underlying necrosis and can be seen in: metastatic carcinoma (or lymphoma) infections (tuberculous or fungal) Whipple disease celiac sprue inflammatory necrotic disorders (e.g. Kikuchi-Fujimoto disease) extra adrenal myelolipoma See also lymphaden...


Pyrexia (or fever) is a clinical sign, indicated by an abnormally elevated core body temperature, which is defined by several medical societies as ≥38.3°C (≥101°F). The temperature elevation may be persistent or episodic. The commonest cause of fever is infection, in one study of hospital inpati...

Zebra spleen

Zebra spleen, also referred to as psychedelic spleen or more correctly inhomogeneous splenic enhancement, refers to the transient heterogeneous parenchymal enhancement of the spleen during the arterial or early portal venous phases of contrast enhancement in CT, MRI, or ultrasound imaging. It i...

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