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Notch sign (primary CNS lymphoma)

The notch sign refers to an abnormally deep depression at the tumor margin in contrast-enhanced MRI in primary CNS lymphoma 1. It is not an uncommon sign in primary CNS lymphoma and can be seen in both immunocompetent and immunocompromised patients. It suggests an irregular growth pattern as wel...

Bright band sign

The bright band sign is a sonographic sign found in the context of splenic infarction. It consists of highly hyperechoic linear-shaped bands within splenic infarct lesions of different ages 1. Histological examinations of spleens with the sign suggest it might be caused by preserved fibrous tr...

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...


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. If the body temperature is greater than 41.5°C - a rare phenomenon - it i...

Zebra spleen

Zebra spleen, also referred to as psychedelic spleen, tigroid splenic enhancement 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,...

Low attenuation lymphadenopathy

Low attenuation lymphadenopathy refers to abnormal lymph nodes that on CT appear to have lower attenuation than other soft tissues. This category can be split into two types: cystic (necrotic) lymph nodes metastatic carcinoma (or lymphoma) infection (tuberculous or fungal) inflammatory necro...

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 disease, and results from microvascular endplate infarction (Figure 1) 3. It may occasionall...

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