The Value Of MRI And ～(31)P MRS In Differential Diagnosis Of Bone And Soft Tissue Tumors

PurposeTo study the morphology and metabolism changes in bone and soft tissue tumors by using method of integrated magnetic resonance imaging (MRI) with phosphorus spectroscopy (³¹P MRS), to explore the value of MRI and ³¹P MRS in differential diagnosis of bone and soft tissue tumors. Materials and methodsMRI and P MRS were performed in 42 cases bone and soft tissue tumor and 12 healthy volunteers. All cases were histologically proved by biopsy or operation. Axial, coronal or sagittal SE T1-weighted , TSE T2-weighted and pd-weighted , TSE T2-weighted FS images were acquired in 1.5T instrument by using either the extremities coil or whole-body coil. ³¹P MRS was performed with the same instrument, by using ³¹P surface coil. MR images were first obtained with 2D FLASH technique (repetition time, 15.0msec; echo time, 5.0msec) with the ³¹P surface coil in position to ensure good localization, then obtained MR spectroscopic data with CSI FID technique (repetition time, 440msec; echo time, 2msec). The areas under the peak of various metabolite in spectra were measured. The spectra were analyzed by taking peak areas relative to peak area of β-ATP and by calculating the PH from the Pj shift relative to P_Cr . Image analysis: Two musculoskeletal radiologist with about 15 years experience who were unware of the pathologic findings reviewed the MR imaging and MRS findings and compared them with pathologic findings. All date were analyzed with Statistical method.Results1. MRI could show the morphology changes in bone and soft tissue tumors and accurately define the extent of lesions, especially the extent of intraosseous and soft tissue involvement as well as the relationship of the lesion to the neurovascular bundle. However, the differences of the size, signal intensity homogeneity, border and involvement of surround structure between benign and malignant lesions had no statistically significant differences. There was great overlap in the MR imaging characteristics of benign and malignant lesions. In most patients, plain MR imaging alone did not distinguish benign lesions from malignant ones.2. Every spectra of bone and soft tissue had seven clear defined metabolite peaks in our study. The characteristic Spectra in normal bone and soft tissue showed a relative high Pcr peak and a relative low PME, Pi and PDE in rest condition.3. Spectra from bone and soft tissue tumors had higher relative levels of PME, Pi and PDE with a concomitant decrease of Pcr compared with 31P spectra from normal bone and soft tissue. The mean peak area rations of PME/ P -ATP, PDE/ P -ATP, LEP/ (3 -ATP, PCr/ P -ATP(PO.Ol), intracellular PH(P<0.05) in malignant group and PME/ 3 -ATP, Pcr/ P -ATP(P<0.01) in benign group were significantly different from that of the normal group. The mean peak area rations of PDE/ P -ATP, LEP/ P -ATP and intracellular PH in benign group were higher than that of the normal group but did not have statistical significance. The mean peak area rations of PME/ (3 -ATP, PDE/ P -ATP, LEP/ P -ATP in malignant group were significantly higher than that in benign group(P<0.01). Although several of the mean peak area rations of benign and malignant groups were statistically significantly different, only the PME/ P -ATP peak area rations have sufficiently little overlap, that might be useful as differential diagnosis of bone and soft tissue tumors. If PME/ P -ATP=1.0 was taken as threshold, then the sensitivity, specificity, accurate, positive and negative predictive values in estimating the potential malignancy of the lesion were 90%, 89.47%, 89.74%, 90%, 89.47%, respectively.4.The sensitivity, specificity, accurate, positive and negative predictive values inestimating the potential malignancy of the lesion were 90.9%, 95%, 92.86%, 95.24%,90.48% by combining MR imaging and spectroscopy.Conclusion1. MR is the most sensitive mothod in detecting the lesions and the most accurate in depicting the extent of involvement of these lesions. It might have aid in diagnosis of bone and soft tissue tumors. But plain MR imaging has limited value in distinguishing benign from malignant tumors.2. 31P MRS has important value in diagnosis and different diagnosis of bone and soft tissue tumors. It should be a simple, non-invasively, effective diagnostic method.3. It is a useful way by combining MR imaging with spectroscopy in differential diagnosis of bone and soft tissue tumors, and that can greatly improve diagnostic specificity in bone and soft tissue lesions. That has important clinical value.