Case Of the Week (COW) 20 December 2015
Fatty infiltration of filum terminale
FINDINGS:
Linear area of increased T1 signal intensity within the spinal canal inferior to L1 level. The lesion (arrow) is well defined and of markedly increased signal intensity, equivalent to fat. Abnormality remains relatively hyperintense on the T2-weighted image. Filum terminale takes a curved course along the posterior aspect of the vertebrae – “bow string appearance”.
DISCUSSION:
Fatty infiltration of the filum has been reported in 6% of autopsy specimens.The thickness of the filum varies, decreasing in diameter caudally. Most often a measurement of less than 2mm is given as normal transverse diameter.However this measurement should be considered at the midpoint, as the normal filum at L5-S1 is much smaller and perhaps less than 1mm . The presence of fat surrounded by fluid will create a chemical shift artifact on most MR imaging sequences. When measuring the fibrolipoma on MR, care should be taken to avoid this boundary misregistration .Fatty infiltration of the filum terminale is a generic term which implies a fibrolipoma within this structure histologically. A lipoma is a mass- like lesion which may or may not be associated with a tethered cord. A fibrolipoma “infiltrates” the filum and tends to be tubular.
Contributed By:
Dr Balaji Ayyamperumal
Tanjavur Medical College
Fatty infiltration of filum terminale
FINDINGS:
Linear area of increased T1 signal intensity within the spinal canal inferior to L1 level. The lesion (arrow) is well defined and of markedly increased signal intensity, equivalent to fat. Abnormality remains relatively hyperintense on the T2-weighted image. Filum terminale takes a curved course along the posterior aspect of the vertebrae – “bow string appearance”.
DISCUSSION:
Fatty infiltration of the filum has been reported in 6% of autopsy specimens.The thickness of the filum varies, decreasing in diameter caudally. Most often a measurement of less than 2mm is given as normal transverse diameter.However this measurement should be considered at the midpoint, as the normal filum at L5-S1 is much smaller and perhaps less than 1mm . The presence of fat surrounded by fluid will create a chemical shift artifact on most MR imaging sequences. When measuring the fibrolipoma on MR, care should be taken to avoid this boundary misregistration .Fatty infiltration of the filum terminale is a generic term which implies a fibrolipoma within this structure histologically. A lipoma is a mass- like lesion which may or may not be associated with a tethered cord. A fibrolipoma “infiltrates” the filum and tends to be tubular.
Contributed By:
Dr Balaji Ayyamperumal
Tanjavur Medical College