Hyperintense intramedullary signal at T2-weighted imaging is a common and important indicator of myelopathy at MRI (1). T2 hyperintensity can reflect many processes at the microscopic level, including edema, blood–spinal cord barrier breakdown, ischemia, myelomalacia, or cavitation (2).
What is an abnormal bone marrow signal?
Abnormal marrow is isointense or hypointense to skeletal muscle on T1-weighted imaging because the replacement of fatty marrow elements by the pathologic process causes loss of the normal fat signal (Fig. 1A, 1B, 1C).
What does heterogeneous marrow signal intensity mean?
This heterogeneous marrow signal most likely represents patchy conversion of red to yellow marrow that is a well-described normal variant seen predominantly in older adults.
What does T1 marrow signal mean?
T1-Weighted Signal. Diffuse or multifocal decreased T1- weighted signal is caused by replacement of fatty marrow, which can be due to cellular tissue or edema. Diffuse benign processes include hematopoietic marrow hyperplasia and hemosiderin deposition.
What does T2 weighted signal mean?
T2 weighted image – Pathology (spine) The same areas are whiter than usual on this T2 image indicating increased water content. Abnormal brightness on a T2 image indicates a disease process such as trauma, infection, or cancer.
What does low signal intensity mean on MRI?
When describing most MRI sequences we refer to the shade of grey of tissues or fluid with the word intensity, leading to the following absolute terms: high signal intensity = white. intermediate signal intensity = grey. low signal intensity = black.
What does signal mean in MRI?
To produce ‘signal’, the MRI scanner interacts with protons in the body. Randomly orientated protons become aligned with the powerful magnetic field in the bore of the scanner. A rapidly repeating sequence of radiofrequency pulses – produced by the scanner – then causes ‘excitation’ and ‘resonance’ of protons.
What does abnormal marrow replacement mean?
The abnormal signal is due to replacement of the small amounts of fat cells normally found in red marrow, such that T1 signal will decrease to or below the signal from disc or muscle. T2 signal is more variable, but will in general increase when compared to muscle.
What does high T2 signal mean?
An increase in T2 signal intensity is often associated with chronic compression of the spinal cord, and it is well established that chronic compression results in structural changes to the spinal cord.
