World Alzheimer’s Day: September 21

World Alzheimer’s Day: September 21

World Alzheimer's Day, September 21st of each year, is a day on which Alzheimer's organizations around the world concentrate their efforts on raising awareness about Alzheimer's and dementia. Alzheimer's disease is the most common form of dementia, a group of disorders that impairs mental functioning.

Reversed halo sign /Atoll sign

Reversed halo sign /Atoll sign

The reversed halo sign (also know as the atoll sign, reverse halo sign, and the fairy ring sign) is defined by central ground-glass opacity with a surrounding halo or crescent of consolidation .

This should not be confused with the halo sign which refers to central consolidation with a surrounding halo or rim of ground-glass opacity.

Furthermore, the reversed halo sign should be differentiated from cavitation (development of focal regions of internal gas) or pseudocavitation (likely internal bronchiolectasis described in subtypes of lung adenocarcinoma).

The reversed halo sign was first described and is most commonly associated with COP but is not specific to this disease. It has been reported in the setting of bacterial pneumonia, mucormycosis, paracoccidioidomycosis, tuberculosis, sarcoidosis, radiofrequency ablation, lymphomatoid granulomatosis, Wegener granulomatosis, tumor, and pulmonary infarcts.

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SPARROW TAIL APPEARANCE OF SUSTANTIA NIGRA IN PARKINSONISM

• Recent advances in MR imaging point the way to a reliable marker for Parkinson disease, which is usually diagnosed almost solely through medical history and clinical findings like muscle stiffness and tremors.
• Three MR imaging-based studies have discovered distinctive changes in the substantia nigra (SN), a crescent-shaped mass of cells in the midbrain that normally produces the neurotransmitter dopamine. 
• Parkinson disease patients lose dopamine-producing cells in the SN, leading to problems with motor control among other symptoms. All three studies showed consistent differences in the appearance of the SN in normal patients compared with patients diagnosed with Parkinson disease.
• The initial study was conducted by neuroradiologists, neurologists and physicists of the University of Nottingham in the U.K., and published in the July 2013 edition of Neurology. Led by resesarchers Anna Blazejewska, Ph.D., and Stefan Schwarz, M.D., the team investigated 7-T MR imaging changes to nigrosome-1 of the substantia nigra revealing an oval shaped structure found in healthy patients but absent in patients with Parkinson disease.
• In a follow-up study by the same research team led by Dr. Schwarz, previous findings were translated to a 3-T MR imaging platform revealing a specific “swallow tail” shape indicating the presence of nigrosome-1—part of the SN that has a dense concentration of dopamine-producing cells. Researchers determined that the split-tail shape was clearly visible in normal patients but not present in the patients with Parkinson disease.

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