Magnetic Resonance Imaging

MRI is useful in detecting myelomatous involvement of the bone marrow. The patterns of infiltration can be focal, diffuse, or mixed.120 In a study of 77 patients examined with MRIs of the thoracic and lumbar spines, three stages of bone disease could be graded: stage I, no focal or diffuse infiltration; stage II, <10 foci or mild diffuse infiltration; and stage III, >10 foci or strong diffuse infiltration. This MRI staging correlates strongly with survival and can be used as a bone lesion scale in Durie-Salmon staging system.121 MRI is also useful in following bone lesions after treatment, as plain radiographs may not show significant changes,

Table 82.4 Diagnostic criteria for (symptomatic) multiple myeloma

(1) Tumor criteria:

Monoclonal plasma cells in the bone marrow >10% and/or

Biopsy-documented plasmacytoma Monoclonal protein in serum and/or urine

(2) End organ damages, one or more of the following Calcium elevation in the blood (serum calcium >10.5 mg/dl or upper limit of normal)

Renal insufficiency (serum creatinine >2 mg/dl) Anemia (hemoglobin <10 g/dl or 2 g/dl < normal) Bone disease: lytic lesions or osteoporosis Others: symptomatic hyperviscosity, amyloidosis, recurrent bacterial infections (>2 episodes in 12 months)

For patients with a solitary bone lesion or osteoporosis without fracture as the sole defining criteria, >30% bone marrow plasmacytosis is required for the diagnosis of systemic myeloma. For monoclonal protein, no specific level is required and it is absent in non-secretory myeloma.

even in responsive disease.122 MRI is the current imaging of choice in evaluating spinal cord compression.

Imaging studies, other than plain radiography, are not routinely used. MRI and PET appear promising, and further investigations may find them useful in detecting focal or residual disease and in better quantifying the extent of disease.123

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