Boaz Karmazyn MD, Presenter: Researcher, Siemens AG

Mervyn David Cohen MBChB, Abstract Co-Author: Consultant, Agfa-Gevaert Group

Kent A. Robertson MD, Abstract Co-Author: Nothing to Disclose

We observed an unusual bright marrow signal on MRI scans of NF1 patients following treatment with Gleevec (Imatinib Mesylate) for plexiform neurofibromatosis. We wanted to evaluate the pattern and evolution of the bone marrow bright signal and its relationship to time of administration of Gleevec.

The data was obtained as part of the IRB approved phase 2 trial of Gleevec in NF1 patients with plexiform neurofibromatosis. Whole body coronal and axial STIR 1.5 Tesla MRI images were obtained prior to and during therapy to evaluate response to treatment. Patients with MRI follow-up of less than one year and patients older than 22 years were excluded. Bone marrow signal was evaluated by 2 pediatric radiologists in consensus. The following was evaluated: 1. Presence of bone marrow bright signal 2. Bones involved 3. Lesion characteristics (patchy/diffuse or focal lesion) 4. Pattern of involvement (single lesion, multifocal or diffuse whole body marrow involvement) 5. Any change in bone marrow signal during follow-up studies  

The study group included 16 patients (8 females and 8 males) with an average age of 14. 3 years (range 4.1-22 years). The average MRI follow-up period was 1.7 years (range 1-2.8 years). The average number of studies per patient was 4 (range 3-6). Fourteen (88%) patients had new bone marrow bright signal after treatment with Gleevec. The abnormality was asymmetric in 9 (64%) patients. Twelve (86%) patients had multifocal bone marrow involvement and 2 (14%) patients had a single lesion. The appendicular skeleton was involved in all 14 patients and the axial skeleton in 4 (29%) patients. The bright signal lesion was either focal (n=9) or diffuse (n=11). The signal decreased in 8 (57%) patients during treatment after an average of 15 months (range 7-35 months) without any observed complications.

Bone marrow bright signal was seen in most patients with NF1 treated with Gleevec. It is likely to represent edema as edema in other organs is a known complication of Gleevec. The bone marrow edema is usually asymmetric, multifocal, and most commonly disappears spontaneously during treatment after an average period of 15 months.

Focal and multifocal marrow bright signal is common in patients with NF1 treated with Gleevec. The bright signal decreases during treatment without observed sequela. It does not represent a tumor.

Karmazyn, B, Cohen, M, Robertson, K, Focal and Multifocal Bright Marrow Signal Observed in Whole Body STIR MR in Children and Young Adults with NF1 Treated with Gleevec (Imatinib Mesylate) for Plexiform Neurofibromas.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9004884.html