Miyuki Takasu, Presenter: Nothing to Disclose

Yuji Akiyama, Abstract Co-Author: Nothing to Disclose

Chihiro Tani MD, Abstract Co-Author: Nothing to Disclose

Keizo Tanitame MD, Abstract Co-Author: Nothing to Disclose

Akira Sakai, Abstract Co-Author: Nothing to Disclose

Kazuo Awai MD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Hitachi, Ltd Research grant, Bayer AG

Shuji Date, Abstract Co-Author: Nothing to Disclose

Toshio Kajima, Abstract Co-Author: Nothing to Disclose

Although the development of the Durie and Salmon PLUS staging system for multiple myeloma has improved the ability to distinguish among disease stages, classifying each stage based on the number of lesions detected on whole-body magnetic resonance imaging (MRI) lacks objectivity. Iterative Decomposition of Water and Fat with Echo Asymmetric and Least Squares Estimation (IDEAL) exploits frequency differences between water and fat protons on MRI and can determine the proportion of fat. We prospectively evaluated the usefulness of the fat fraction on IDEAL sequences for predicting the multiple myeloma stage.

The lumbar spine was examined on a GE 3.0T scanner in 20 patients with multiple myeloma and 26 sex- and age-matched normal controls (mean 62.2 and 63.1 years, respectively). Based on International Myeloma Working Group (IMWG) criteria, myeloma was asymptomatic in 11 and symptomatic in 9 patients. Vertebral bodies with any focal lesions were excluded. The fat fraction was calculated as the mean value in rectangular voxels defined in the internal area of the vertebral body (L1 to L3). One-way analysis of variance with Scheffe post hoc test was used to compare the fat fraction in controls, asymptomatic myeloma, and symptomatic myeloma. The correlation between the fat fraction and the serum β2-microglobulin-to-albumin ratio was studied with Pearson’s correlation coefficient test. Differences were considered significant at p<0.05.

The fat fractions was 72.8 ± 5.3% and 70.3 ± 8.8% and 47.6 ± 16.9% in the controls, asymptomatic-, and symptomatic myeloma, respectively; it was significantly lower in patients with symptomatic myeloma (p<0.01). There was a significant relationship between the fat fraction and the serum β2-microglobulin-to-albumin ratio (r=0.57, p<0.01).

Quantitative fat imaging techniques could provide a sensitive measure of bone marrow invasion by multiple myeloma. The fat fraction differentiated between asymptomatic and symptomatic patients and correlated with the standard laboratory tests on which the IMWG classification system is based.

The vertebral fat fraction obtained by IDEAL sequence on MRI correlates with the standard laboratory tests and may help to predict the transition from asymptomatic to symptomatic myeloma.

Takasu, M, Akiyama, Y, Tani, C, Tanitame, K, Sakai, A, Awai, K, Date, S, Kajima, T, Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-Squares Estimation (IDEAL) Imaging of Multiple Myeloma: Initial Clinical Efficiency Results.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006969.html