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Pelvic marrow in adults
C D Levine1, M E Schweitzer, S M Ehrlich
1Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania.
Abstract:
The appearance of hematopoietic marrow in magnetic resonance (MR) imaging is variable and differences between normal and pathologic marrow may be subtle. To aid in the evaluation of this problem, we reviewed 82 consecutive pelvic MR examinations in men with no evidence of osseous metastases. Images were evaluated with regard to the overall fraction of residual hematopoietic marrow present and the characteristics of this marrow. The patient population in our study was older (mean age 66 years) than the patient populations in previous papers documenting normal marrow patterns. The overall amount of hematopoietic marrow present was less in this older patient population, with 80% of patients having less then 40% residual hematopoietic marrow. A consistent pattern of morphologic change was noted as hematopoietic marrow converted to fatty marrow with increasing age. Initially, hematopoietic marrow tended to appear diffuse, heterogeneous, and with poorly defined margins on MR imaging. As conversion to fatty marrow continued, hematopoietic marrow became more focal and sharply defined, usually in the form of islands of residual hematopoietic marrow. Periarticular hematopoietic marrow predominated in the sacroiliac region (72% of patients) with little residual hematopoietic marrow noted in the symphysis pubis (5%) and hip joints (30%). Hematopoietic marrow persisted longer in juxtacortical locations (87%), was always symmetric (100%), remained less intense than fat on T2-weighted images (100%), and usually had a central focus of fat (98%). These morphologic criteria may be of value in establishing the MR appearance and patterns of marrow in the pelvis, and in the recognition and confident diagnosis of foci of hematopoietic marrow.
Insights
Magnetic resonance (MR) imaging of hematopoietic marrow in older men shows less marrow overall, with specific patterns of change. These findings help identify normal marrow variations and diagnose subtle pathologies.
Area of Science:
- Radiology
- Medical Imaging
- Skeletal System Imaging
Background:
- Hematopoietic marrow appearance on magnetic resonance (MR) imaging is variable.
- Distinguishing normal from pathologic marrow can be challenging due to subtle differences.
Purpose of the Study:
- To evaluate the characteristics of hematopoietic marrow in older men using MR imaging.
- To establish morphologic criteria for identifying normal hematopoietic marrow patterns in the pelvis.
Main Methods:
- Review of 82 pelvic MR examinations in men without osseous metastases.
- Evaluation of the fraction and characteristics of residual hematopoietic marrow.
- Analysis of marrow patterns in relation to patient age and location within the pelvis.
Main Results:
- Older patients (mean age 66) had less hematopoietic marrow (80% < 40% residual).
- Hematopoietic marrow conversion to fatty marrow followed a consistent pattern: diffuse to focal, with sharp margins.
- Periarticular hematopoietic marrow was common in the sacroiliac region (72%).
- Hematopoietic marrow persisted in juxtacortical locations (87%), was symmetric (100%), less intense than fat on T2-weighted images (100%), and often had a central fat focus (98%).
Conclusions:
- Established morphologic criteria aid in recognizing normal pelvic hematopoietic marrow patterns on MR imaging.
- These criteria assist in the confident diagnosis of hematopoietic marrow foci.
- Understanding age-related changes in marrow appearance is crucial for accurate interpretation.