Diffusion-weighted MRI Study On Lumbar Multiple Myeloma

Objective To discuss the MRI features of the lumbar multiple myeloma(MM).To study diffusion-weighted imaging(DWI) on patients with lumbar multiple myeloma and evaluate the difference of signal noise ratio(SNR) and apparent diffusion coefficients (ADCs) in diagnosis.Methods 20 patients with lumber MM(confinnde by clinic and pathology) and 20 controls were performed with sagittal SE T1WI,FSE T2WI,Fat saturation FSE T2WI (FS-FSE T2WI) and single-shot spin-echo echoplanar DWI(SS-SE-EPI-DWI), respectively.Analysis MRI features of different Types of MM.The difference of SNR on FSE T2WI and FS-FSE T2WI and ADCs of lumbar MM and normal vertebrae on DWI with different b values were analyzed.ADC maps were reconstructed and observed in patients with lumbar MM.Results(1)Routine MRI appearance:The vertebral MM was classified into the following four types:Normal type accounted for 15%,in which the lesions were mild hyper-intensity on T1WI,iso-intensity on T2W1 and hypo-intensity on DWI.Diffuse type accounted for 25%,in which the lesions were diffuse hypo-intensity with clear border on T1WI,hyper-intensity with indistinct border or iso-intensity on T2WI and hyper-intensity on DWI.Localized type accounted for 45%,in which the lesions were multiple nodular or patchy hypo-intensity on T1WI,mild hyper-intensity or iso-intensity on T2WI and hyper-intensity on DWI."Salt with pepper"type accounted for 15%,in which the lesions were diffuse spot-like mixed hyper-,iso-and hypo-intensity.All lesions were hyper -intensity on FS-FSE T2W1.(2) SNR_T2WI-SNR_FS-T2WI:On T2WI,SNR difference of bone marrow on FSE T2WI and FS-FSE T2WI of MM group(2.99±3.91) was significantly lower than the control group(9.19±2.83).(3)ADC:the ADCs of leisions and normal vertebra in control group were:b=400s/mm²(0.972±0.414,0.885±0.367),b=600s/mm² (0.503±0.272,0.494±0.273).The former are significantly higher than the the latter(P＜0.01).The absolute values and the 95%CIs of these two entities showed substantial overlap.There were no difference in the ADCs of the same ROIs on DWI between different b values.Conclusion SS-SE-EPI-DWI(single-shot spin-echo echoplanar imaging diffusion -weighted imaging) of the spine is feasible for quantitative analysis of diffusion effects, and the ADCs calculated from diffusion-weighted MR images is a reliable parameter with which to distinguish multiple myeloma from normal vertebrae.