The Many Faces of Marrow Necrosis

Area of Science:

• Radiology
• Bone Diseases
• Medical Imaging

Background:

• Bone marrow can be fatty or hematopoietic, varying with age and skeletal location.
• Both fatty and hematopoietic bone marrow are susceptible to marrow necrosis.
• Marrow necrosis is a significant pathological process affecting bone marrow.

Approach:

• This review focuses on magnetic resonance imaging (MRI) findings in disorders where marrow necrosis is predominant.
• It details specific MRI sequences and findings for diagnosing fatty marrow necrosis, including the reactive interface on T1-weighted images.
• It also describes imaging characteristics of nonfatty marrow necrosis, emphasizing its appearance on fat-suppressed fluid-sensitive sequences and post-contrast enhancement.

Key Points:

• Fatty marrow necrosis shows a reactive interface on T1-weighted MRI; collapse is a complication seen on fat-suppressed sequences or radiographs.
• Nonfatty marrow necrosis is less common, poorly visualized on T1-weighted images, but detectable on fat-suppressed sequences or by lack of contrast enhancement.
• The review differentiates true marrow necrosis from conditions historically mislabeled as osteonecrosis.

Conclusions:

• MRI is crucial for diagnosing marrow necrosis and its subtypes.
• Specific MRI sequences and findings aid in identifying fatty and nonfatty marrow necrosis.
• Distinguishing true marrow necrosis from similarly presenting conditions like osteonecrosis is important.