Henrik J. Michaely MD, Presenter: Consultant, Bayer AG

Georgia Metzgeroth, Abstract Co-Author: Nothing to Disclose

Stefan Haneder MD, Abstract Co-Author: Nothing to Disclose

Stefan Oswald Schoenberg MD, PhD, Abstract Co-Author: Nothing to Disclose

Philipp Riffel MD, Abstract Co-Author: Nothing to Disclose

Wolf-K. Hofmann, Abstract Co-Author: Nothing to Disclose

Andreas Reiter, Abstract Co-Author: Nothing to Disclose

To evaluate if whole-body MR-imaging allows differentiating between aggressive systemic mastocytosis (ASM) and indolent systemic mastocytosis (ISM).

In this IRB approved study, 43 consecutive patients (22F, 21M) with clinically proven systemic mastocytosis according to the WHO criteria underwent a whole-body (wb) MR-exam at 1.5T (Siemens Avanto) including coronal wb-T1w-TSE imaging, coronal wb-STIR-.imaging and dynamic contrast-enhanced T1w-VIBE imaging of the abdomen. Image evaluation included the pattern and extent of pathologic bone marrow signal in the spine and the extremities, the presence of ascites, pathologic lymph nodes, hepatosplenomegaly and focal organ lesions. The clinical diagnosis of ASM and ISM was based on the current WHO-criteria.

18 patients were diagnosed with ASM, 25 with ISM. 18/18 ASM patients revealed a pathologic bone marrow pattern (sclerosis in 10/18, tumor cell infiltration in 8/18 patients) compared to only 9 patients in the ISM group (sclerosis 2/25, tumor cell infiltration 5/25) (p<0.0001). Extension of the pathologic bone marrow signal into the extremities was seen in all 18 ASM patients but only in 5/25 ISM patients (p<0.0001). In ASM pathologic lymph nodes, hepatosplenomegaly and ascites were present in 12/18, 12/18 and 17/18 patients while in the ISM group these findings were seen in 0/25 (p=0.003), 6/25 (p=0.0008) and 3/25 (p< 0.0001) patients. Focal organ lesions were exclusively found in 4/18 ASM patients (p>0.05).

Wb-MRI is able to differentiate between ASM and ISM based on the specific pattern of bone marrow changes in combination with the presence of pathologic lymph nodes, focal organ lesions and ascites.

Wb-MRI allows to differentiate ISM from ASM and might be used for therapy assessment in patients with ASM. In addtion, the distinctive findings in ASM allow to rule out other bone marrow pathologies.

Michaely, H, Metzgeroth, G, Haneder, S, Schoenberg, S, Riffel, P, Hofmann, W, Reiter, A, Whole-body MR Imaging Allows to Differentiate Indolent from Aggressive Systemic Mastocytosis.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11001759.html