Learning objectives
To explain the bone marrow appearances on MRI according to its different composition.
To explain the technical basis of DIXON sequence in the assessment of bone marrow in comparison to morphological T1-weighted and fluid-sensitive images.
To discuss the differential diagnosis of bone marrow pathology based on MRI patterns.
To enhance with clinical cases the potential benefit of using Dixon sequence in bone marrow analysis.
Background
The bone marrow is a large organ that is responsible for normal hematopoiesis.
The cellular structure of bone marrow is complex,
containing stem cells responsible for the production of erythrocytes,
granulocytes,
monocytes,
lymphocytes,
and platelets.
Bone marrow can be divided into two types:
- - yellow (fatty) marrow: contains more fat,
approximately 80%,
and is less cellular.
- - and red (hematopoietic) marrow: about 70% is composed of cellular elements,
that contain mostly water,
and about 30% consists of fatty elements.
Red marrow contains the...
Imaging findings OR Procedure Details
CSI from Dixon sequence is useful for differentiating non-marrow-replacing processes (that are usually benign) from marrow-replacing processes (that are usually malignant lesions) but it does not inherently differentiate between benign and malignant lesions.
Thus,
it is important to understand the bone marrow composition changes within the different clinical scenarios.
The usefulness of the CSI in bone marrow clinical applications include some of the bone marrow signal alterations that may mimic marrow-replacing tumors in morphologic sequences as T1-W and fluid-sensitive images,
as they are abundant red...
Conclusion
Dixon sequence is a water-fat separation method based on chemical shift imaging (CSI),
and can be applied to TSE or GE sequences and to T1-weighted and T2-weighted images.
In only one acquisition 4 sets of images are obtained: water only,
fat only,
in and out of phase.
MRI is an excellent non-invasive modality for evaluating bone marrow and detecting marrow lesions.
MRI with morphological sequences as T1-weighted images has a high sensitivity for detecting both diffuse and focal bone marrow involvement.
In spite of its...
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