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Watershed (borderzone) infarcts

Case contributed by Naushad Ali Basheer Ahamed
Diagnosis certain

Presentation

The patient is an 8 month old girl, a known case of sickle cell anemia who presented with sickle cell crisis, loss of consciousness and severe shortness of breath. Patient started to develop tonic clonic convulsion which were focally localized mainly to the right arm with associated up-rolling of eyes. CT of the brain was unremarkable.

Patient Data

Age: 8 months
Gender: Female

There are multiple bilateral near symmetrical foci of restricted diffusion (appearing hyperintense on DWI with corresponding ADC images showing dark signal) seen in both cerebral hemispheres seen involving the deep white matter and subcortical white matter. There is no perilesional edema. No large territorial infarctions. No gyral swelling or sulcal effacement. DWI / ADC : b1000, TR - 5600; TE 98; 3T Siemens Skyra

On FLAIR, these are synced T2 FLAIR and T2* GRE (Hemo sequence). The lesions seen in the DWI/ADC sequences are less conspicuous in the T2 FLAIR images. These are not foci of petechial hemorrhage as they do not show susceptibility artifact in the T2* GRE images. T2 Flair : TR - 6000; TE - 85; TI - 2028 T2*GRE : TR - 600; TE - 19.9; Flip angle - 12 degrees, 3T Siemens Skyra

On MRA, the time of flight MR angiogram was normal.

Case Discussion

Watershed infarctions typically occur at the junctional zones or border zone of the arterial territories due to reduced cerebral perfusion of variable etiologies.

  1. external or Cortical watershed infarcts: these are the more common ( and widely published ) variety of watershed infarctions. These are seen at the junction of the major arterial territories, most commonly between the anterior cerebral artery (ACA) - middle cerebral artery (MCA) and middle cerebral artery (MCA) – posterior cerebral artery (PCA). These are seen as larger confluent white matter hyper-intensities on T2 weighted MR images and are usually wedge-shaped or oval in shape
  2. internal watershed infarcts: these are relatively smaller foci of restricted diffusion seen symmetrically in both cerebral hemispheres, in the deep white matter, subcortical white matter, and in the basal ganglia region in particular in the zone of the lenticulostriate perforator circulation

Case courtesy Dr. Ahmed Ajamy Elsayed

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