Answer for BIR CoW 13 May 2018
BRAINSTEM 3T DWI PSEUDOLESION
Findings
Hyperintense signal in Diffusion weighted imaging (DWI)with no corresponding hypointensity in ADC map , noted in anterior midbrain within the decussation of superior cerebellar peduncles . No corresponding FLAIR hyperintensity noted.
Discussion
A number of artifacts can occur on FLAIR imaging and can simulate disease. Many of these require increasing awareness at higher field strengths or with the implementation of volumetric 3D acquisition Such pseudolesions seem to be noted most commonly in regions that undergo myelination later (e.g., the PVWM posteriorly), at the edge of orwithin regions of active myelination in children (e.g., PVWM orCST in infants), or in regions of high diffusion anisotropy (e.g.,CST or DSCP). On 3 T FLAIR and DWI, the decussation of the superior cerebellar peduncles (DSCP) is another fairly common sitefor mild hyperintensity, likely owing to normal high anisotropy,which may be the cause of the bright signal on DWI,with a mildly bright signal on T2WI (“T2 shine-through,”perhaps due to focally prominent interstitial fluid). Occasionally, this signal occurs in the SCPs themselves.Whatever the cause of this normal signal, differential considerationsinclude vascular/ischemic conditions (lacunarinfarction), demyelinating disorders such as MS, metabolicdisorders such as Wernicke’s encephalopathy, or infectiousdisorders like rhombencephalitis. DSCP may appear mildly hyperintense on one sequence and have normal or low signal on another . Hyperintensity within DSCP may not be apparent on all three sequences (FLAIR, T2WI or DWI) or may be present in one only one plane or only on one sequence . Recognition of brain pseudolesions like the above is important to avoid erroneous interpretations
Ref: Atlas of Normal Imaging Variations of the Brain, Skull, and Craniocervical Vasculature –Vol 1 Springer 2017. Alexander M. McKinney
Findings
Hyperintense signal in Diffusion weighted imaging (DWI)with no corresponding hypointensity in ADC map , noted in anterior midbrain within the decussation of superior cerebellar peduncles . No corresponding FLAIR hyperintensity noted.
Discussion
A number of artifacts can occur on FLAIR imaging and can simulate disease. Many of these require increasing awareness at higher field strengths or with the implementation of volumetric 3D acquisition Such pseudolesions seem to be noted most commonly in regions that undergo myelination later (e.g., the PVWM posteriorly), at the edge of orwithin regions of active myelination in children (e.g., PVWM orCST in infants), or in regions of high diffusion anisotropy (e.g.,CST or DSCP). On 3 T FLAIR and DWI, the decussation of the superior cerebellar peduncles (DSCP) is another fairly common sitefor mild hyperintensity, likely owing to normal high anisotropy,which may be the cause of the bright signal on DWI,with a mildly bright signal on T2WI (“T2 shine-through,”perhaps due to focally prominent interstitial fluid). Occasionally, this signal occurs in the SCPs themselves.Whatever the cause of this normal signal, differential considerationsinclude vascular/ischemic conditions (lacunarinfarction), demyelinating disorders such as MS, metabolicdisorders such as Wernicke’s encephalopathy, or infectiousdisorders like rhombencephalitis. DSCP may appear mildly hyperintense on one sequence and have normal or low signal on another . Hyperintensity within DSCP may not be apparent on all three sequences (FLAIR, T2WI or DWI) or may be present in one only one plane or only on one sequence . Recognition of brain pseudolesions like the above is important to avoid erroneous interpretations
Ref: Atlas of Normal Imaging Variations of the Brain, Skull, and Craniocervical Vasculature –Vol 1 Springer 2017. Alexander M. McKinney
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!