[Staging of multiple myeloma with MRI: comparison to MSCT and conventional radiography]

The staging of patients with multiple myeloma demands sensitive imaging methods for the assessment of the skeletal system. MRI allows for direct visualization of the bone marrow which exhibits five different infiltration patterns in multiple myeloma: 1. normal appearance of the bone marrow, 2. focal involvement, 3. homogeneous diffuse infiltration, 4. combined diffuse and focal infiltration, 5. "salt and pepper" pattern with inhomogeneous bone marrow signals due to multiple fat islands. The combination of T1w-SE and STIR sequences is best suited for detecting all infiltration patterns and for the differential diagnoses e. g. hemangiomas. With parallel imaging in MRI, acquisition times can be markedly reduced and whole-body screening of the bone marrow can be achieved within 30 min. MRI is superior to radiography for the detection of focal as well as diffuse infiltration. Multidetector computed tomography and especially 16- and 64-detector row scanners allow fast imaging with thin slice collimation and multiplanar reconstructions. With low-dose protocols, effective dose reduction can be achieved, so that radiation exposure is only slightly higher than that of a whole-body skeletal x-ray exam. Sensitivity of MSCT is markedly superior to conventional radiography. Due to the direct visualization of the bone marrow with MRI, MRI is superior in detecting early infiltrations with myeloma cells without osteolyses. In advanced multiple myeloma, CT on the other hand, enables for more precise assessment of bony destructions and fracture risk.