Diagnostic Value Of The Mr Diffusion Weighted Imaging In Spinal Metastases

Objective:To study diffuse-weighted MR imaging on patients with spinal metastases and evaluate the value of signal attenuation ratio and apparent diffuse coefficient in diagnosis.Materials and Methods:40 patients with spinal metastases (confirmed by clinic or pathology) were performed with sagittal SE T1WI,TSE T2WI,fat saturations TSE T2WI(TSE T2WI/FS) and single-shot spin-echo echoplanar DWI, respectively. The capability to show the lesion on SE TI WI,TSE T2WI,TSE T2WI/FS and DWI (b=500 s/mm2) were compared. Meanwhile, on DWI with different b value, the ADCs and SARs of spinal metastases and normal vertebral were analyzed,ADC maps were restructed.Results:(1) General MRI and DWI appearance:There were 76 lesions in 40 patients. The signal intensity of lesions were showed hypointense on SE-T1WI mostly, slight hyperintense, isointense,hypointense and mixed signal intensity on TSE T2WI, and hyperintense on TSE T2WI/FSand DWI mostly. (2) The capability to show the lesions on DWI (b=500 s/mm2) and general MRI The capability to show the lesions on T1WK T2WI/FS and DWI (b=500 s/mm2) were similar (P>0.01,α=0.0083), which were higher than that of TSE T2WI (P <0.001,α=0.0083). (3)SAR:The SARs of lesions and normal vertebrae were:b=300 s/mm2, 32.43±1.46%.14.94±1.34%; b=500s/mm2,48.04±1.55%,21.69±1.60%. The SARs of lesions were evidently higher than that of normal vertebrae at the same imaging parameters(P<0.01). The upper bound of 95%confidence interval for SAR(b=500 s/mm2) of normal vertebral was 24.91%,which was considered as the threshold of vertebral metastetics, sensitivity was 94.7%, specificity was 70.7%. (4)ADC:The ADCs of lesions and normal vertebrae were:b=300 s/mm2,13.68±1.75X10-4 mm2/s,5.56±0.54 X10-4 mm2/s; b=500 s/mm2,13.80±0.63 X10-4 mm2/s,5.06±0.42 X10-4 mm2/s.The ADCs of lesions were evidently higher than that of normal vertebrae at the same imaging parameters(P<0.01). The upper bound of 95%confidence interval for ADC(b=500 s/mm2) of normal vertebral was 5.91 X10-4 mm2/s,which was considered as the threshold of vertebral metastetics, sensitivity was 91.9%, specificity was 78.1%. (5) The SARs of osteolytic, compounded and osteogenic metastatic (b=500 s/mm2) The SARs of osteolytic,compounded and osteogenic metastatic were 58.87±3.99%,48.87±1.56%, 34.48±3.58%, their differences were statistically significant(P<0.01). (6) The ADCs of osteolytic,compounded and osteogenic metastatic (b=500 s/mm2) The ADCs of osteolytic,compounded and osteogenic metastatic were 18.83±2.16 X10-4 mm2/s,13.89±4.42 X10-4 mm2/s,8.77±1.07 X10-4 mm2/s, their differences were statistically significant(P<0.01). (7) Correlation between SARs and ADCs:On DWI, there were positive correlations between SARs and ADCs of the same ROIs at the same imaging parameters.The correlations were statistically significant(P<0.01). (8) ADC map:ADC maps could visually reflect the diffusion ability of various tissues.The metastases showed brighter signal than the normal vertebrae on the map mostly.Conclusions:DWI could efficiently reflect the diffusion characterizations. The spinal mestastases and normal vertebrae could be accurately distinguished by comparing the SARs and ADCs.