[The diagnosis of plasmocytoma with MRT]

In multiple myeloma 5 different infiltration patterns can be differentiated: 1. normal appearance of bone marrow, 2. focal involvement, 3. homogeneous diffuse infiltration, 4. combined diffuse and focal infiltration, 5. "salt- and pepper" pattern with inhomogeneous bone marrow with interposition of fat islands.

For the fast and total acquisition of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique is superior. The focal involvement is clearly demonstrated as areas of high signal intensity on e.g. STIR images. Diffuse involvement can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. MRI is superior to X-ray in focal and diffuse involvement. With ultrafast sequences a "screening" of the whole red bone marrow as for myeloma infiltration is possible.

In prognosis studies diffuse infiltration is inferior to focal involvement. Patients without bone marrow infiltration have a significantly longer survival than patients with bone marrow infiltration in MRI at the time of diagnosis. However, even patients in stage one of disease (Durie and Salmon) and negative X-ray films can show bone marrow infiltration in MRI. Those patients often show an early disease progression. Good response to therapy in focal involvement are: reduction of signal intensity on T2-weighted spin echo images, lack or rim-like enhancement after contrast material injection or even a normalisation of bone marrow signal. In case of diffuse involvement a partly patchy reconversion to fatty marrow can be seen.