· Human beings are born with red /
hematopoietic marrow in their entire skeleton, which gets gradually replaced by
fat as age progresses, and reaches the mature state by the age of 25years.
·
In adult pattern the red marrow is
seen in the axial skeleton and proximal appendicular skeleton.
·
The red / hematopoietic marrow SI
in neonates may be slightly lower than that of the skeletal muscle; thereafter marrow
the signal intensity increases. So if the Marrow SI is found to be lower than
of the normal skeletal muscle it almost always indicate a marrow pathology.
·
Under 40yrs of age, the axial
skeleton contains fat only at the basivertebral vein region.
·
The replacement of the red to
yellow marrow can occur in 3 patterns :
1.
Bandlike pattern along the
endplate.
2.
Small foci of replacement.
3.
Larger globular areas of fatty
replacement.
·
Near complete fatty replacement
may be seen in some elderly patients and in cases of malnutrition or
osteoporosis.
·
Conditions increasing the need for
hematopoiesis like Chronic hypoxia, Anemia etc can cause reversal of fatty
replcament, back to red marrow. These are usually seen as patches of T1
hypointensity.
·
In cases of Sickle cell disease where the yellow marrow,can convert back to red marrow OR may never convert Yellow.
The red marrow contains 40% of fat and yellow marrow contains 80% of fat !!!
Ref : AJR article MRI of spinal bone marrow -Part I. 2011.
In cases of Sickle cell disease where the yellow marrow,can convert back to red marrow OR may never convert Yellow.
The red marrow contains 40% of fat and yellow marrow contains 80% of fat !!!
Ref : AJR article MRI of spinal bone marrow -Part I. 2011.
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