Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging of multiple myeloma: Initial clinical efficiency results

Objectives To evaluate the effectiveness of the iterative decomposition of water and fat with echo asymmetric and least-squares estimation (IDEAL) MRI to quantify tumour infiltration into the lumbar vertebrae in myeloma patients without visible focal lesions. Methods The lumbar spinewas examined with 3 T MRI in 24 patients with multiple myeloma and in 26 controls. The fatsignal fraction was calculated as the mean value from three vertebral bodies. A post hoc test was used to compare the fatsignal fraction in controls and patients with monoclonal gammopathy of undetermined significance (MGUS), asymptomatic myeloma or symptomatic myeloma. Differences were considered significant at P<0.05. The fat-signal fraction and β -microglobulin-to-albumin ratio were entered into the discriminant analysis. Results Fat-signal fractions were significantly lower in patients with symptomatic myelomas (43.9 ±19.7%, P<0.01) than in the other three groups. Discriminant analysis showed that 22 of the 24 patients (92%) were correctly classified into symptomatic or non-symptomatic myeloma groups. Conclusions Fat quantification using the IDEAL sequence in MRI was significantly different when comparing patients with symptomaticmyeloma and those with asymptomatic myeloma. The fat-signal fraction and β -microglobulin-to-albumin ratio facilitated discrimination of symptomatic myeloma from nonsymptomatic myeloma in patients without focal bone lesions. Key Points • A new magnetic resonance technique (IDEAL) offers new insights in multiple myeloma. • Fat-signal fractions were lower in patients with symptomatic myelomas than in those with asymptomatic myelomas. • The β -microglobulin-to-albumin ratio also aided discrimination of symptomatic myeloma. • The fat-signal fraction may provide information about the myeloma cell mass. © European Society of Radiology 2012.