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 spine was examined with 3 T MRI in 24 patients with multiple myeloma and in 26 controls. The fat-signal fraction was calculated as the mean value from three vertebral bodies. A post hoc test was used to compare the fat-signal 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 ß(2)-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 symptomatic myeloma and those with asymptomatic myeloma. The fat-signal fraction and ß(2)-microglobulin-to-albumin ratio facilitated discrimination of symptomatic myeloma from non-symptomatic 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 ß2-microglobulin-to-albumin ratio also aided discrimination of symptomatic myeloma. • The fat-signal fraction may provide information about the myeloma cell mass.

Effects of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid on T2-weighted MRCP.

PURPOSE: Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is a recently developed liver-specific contrast agent for magnetic resonance (MR) imaging that is excreted equally via the kidneys and the biliary system. To our knowledge, its effects on T(2)-weighted MR cholangiopancreatography (MRCP) images have not been explored. Acquisition of the hepatobiliary phase is recommended 20 min after administration of Gd-EOB-DTPA. Examination time cannot be extended if the contrast does not take effect on T(2)-weighted MRCP within 20 min after administration. We attempted to assess the change in signal of T(2)-weighted MRCP by excretion of Gd-EOB-DTPA. METHODS: Between March and July 2008, 40 patients (15 women, 25 men; mean age 70.8 years) were examined with abdominal MR imaging. T(2)-weighted MRCP was performed before and 10 and 20 min after administration of Gd-EOB-DTPA. We analyzed signal intensity of the bile duct, gallbladder, cystic duct, and pancreatic duct on MRCP for changes in intensity. RESULTS: T(2)-weighted MRCP 20 min after contrast administration showed loss of signal of the bile duct (intrahepatic bile duct in all cases, upper extrahepatic duct in 36 [90%], middle extrahepatic duct in 33 [85%], and lower extrahepatic duct in 26 [67%]), the gallbladder in 23 cases (72%), and the cystic duct in 25 (64%). This signal change increased with time. We observed no change in signal of the pancreatic duct. CONCLUSION: T(2)-weighted MRCP sequences should not be obtained after administration of Gd-EOB-DTPA because this contrast agent decreases signal intensity of the biliary structure on these images.

A case of MELAS: hyperperfused lesions detected by non-invasive perfusion-weighted MR imaging.

We report a case of MELAS in which lesions were detected by perfusion-weighted MR imaging. Perfusion-weighted MRI using contrast media (PWI) and FAIR (flow-sensitive alternating inversion recovery), an arterial spin labeling method, clearly showed these lesions as hyperperfused areas. One of these lesions, diminished after steroid therapy, could also be detected by FAIR.