MR imaging of bone marrow : NHL

45 year old female with NHL shows diffuse marrow signal alteration appearing hypointense on T1 weighted images and hyperintense on STIR images. 

Learning Points

• In patients with hematopoietic malignancies the diagnosis of neoplastic bone marrow infiltration is crucial to determine prognosis and to identify suitable treatment protocols
•  In non-Hodgkin’s lymphoma (NHL) a neoplastic bone marrow infiltration indicates the highest stage (stage four) according to the Ann Arbor Classification. The iliac crest biopsy may be false negative when the bone marrow infiltration is focal rather than diffuse
•  Neither MR nor FDG-PET is meant to replace marrow biopsy, because the histopathologic subtype of lymphoma has to be defined, and because minimally diffuse, microscopic marrow involvement can be false negative with either imaging technique 
•  On the other hand, routinely performed iliac crest biopsies cover only a small portion of the entire bone marrow and also provide potential false-negative findings 

Normal Bone Marrow

• In adults, the normal bone marrow is characterized by a partial or complete fatty conversion and low cellularity, which leads to a relatively high signal intensity on plain T1-weighted images and low signal intensity on STIR- or fat saturated T2-weighted MR images 
•  In children, the normal bone marrow is highly cellular, which leads to a low signal intensity on plain T1-weighted images and high signal intensity on STIR- or fat saturated T2-weighted MR images.
•  Within long bones, it first involves the epiphyses, then the diaphyses and, finally, the metaphyses. In the vertebrae, it starts in the center, around the venous plexus, and progresses peripherally

Reference and Further Reading : Daldrup-Link HE, Henning T, Link TM. MR imaging of therapy-induced changes of bone marrow. European Radiology. 2007;17(3):743-761. doi:10.1007/s00330-006-0404-1.