Research Of BOLD To Identify Benign And Malignant Tumor Of The Bone And Soft Tissue

Objective: The clinical treatment of benign and malignant tumor of thebone and soft tissue is different, the identification of them is very important, toguide the choice of clinical treatment and judge prognosis. The pattern ofangiogenesis in benign and malignant tumor is different. In the peripheral areaof malignant tumor, the angiogenesis is mainly composed of capillaries andhost venules, which then grow into the tumor. These vessels are mostly mature,the blood supply of tumor is abundant. However, in the central region ofmalignant tumor, it is neovascularity formed by the tumor cells. These vesselsare immature, and because smooth muscles are lacked in the wall, itspermeability is higher, so that it will result in ischemia, hypoxia and necrosis.Angiogenesis of benign tumor is mature, the blood supply has no obviousdifference between the central and peripheral area. Neoplastic MR perfusionhas found the difference blood supply model of benign and malignant tumor.Animal studies also detect that central area of the tumor has the lowerresponse to the stimulation（such as high oxygen, et）than the peripheral area.Blood flow of the tumor is instable, BOLD-fMRI can show the spontaneousflow fluctuations. In this study, we use BOLD-fMRI to scan the tumor of boneand soft tissues, and analysis the BOLD signal aiming to find out thedifference between benign and malignant tumor, or different areas of thetumors.Methods: The3D-T1WI and BOLD images of92patients who havebone and soft tissue tumor were preformed by the1.5Tesla MR scanner(Magnetom Avanto, Siemens, Erlangen, Germany).3D-T1WI images were performed by the turbo FLASH (turbo fast lowangled shot) sequence with the following scan parameters: repetition time(TR),1900ms; echo time (TE),2.97ms; slice/gap,1/0.5mm; flip angle,15°; scanning layers,176slices; field of view (FOV),220mm×220mm.The SE-EPI-BOLD sequence was performed with the parameters asfollowing: repetition time(TR),2000ms; echo time(TE),400ms; slice/gap,5/1mm; the voxel size,3.44mm×3.44mm×6.0mm; field of view (FOV),220mm×220mm; matrix size,64×64; scanning layers,20slices; scanning time,6min.Under the MATLAB2010a software, we performed the data processingand removed the linear trends using the SPM8and the REST software.Removing the unqualified cases, there were74patients, including52caseswith malignant tumor and22with benign tumor. Two experimenters chose3ROI in the central and the peripheral areas of the tumors of92patients andnormal muscles of61patents respectively, to avoid the necrosis, calcification,ossification and large blood vessels. Then using REST software picked up theaverage time signal of the all voxels within the selected ROI, and the averagecoefficient of variance（CV）of BOLD signal in the different areas to dostatistics. We completed the statistical test by ANOVA and Post hoc pairwisecomparison analysis. Furthermore, comparing the difference of same areas andthe difference△C V of periphery-central CV between malignant and benigntumor used Two-Independent samples t-tests or Two-Independent samplesNonparametric tests; but using paired t-tests to compare different locationeffect for both malignant and benign tumor. In this study, two experimenters(xing and wang) chose the ROI according to the same specific principlesrespectively. Xing had two options (xing1, xing2) week apart, independent ofeach other. Then calculated the values of intrarater (xing1and xing2) andinterrater correlation coefficient (xing1and wang; xing2and wang) to evaluatethe repeatability of choosing ROI.Result: The results of the ANOVA analysis show that the CV of theBOLD signal in central region of malignant tumors is greater than theperipheral area; but in begin tumor, the CV of the BOLD signal of peripheralarea is greater than normal muscle. The difference of CV of BOLD signal timebetween the peripheral region and central region is greater in malignant tumor than that of benign tumor. The CV of BOLD signal time of the central zonesand peripheral zones between benign and malignant tumor had no statisticallysignificant difference.ICC analysis of repeatability shows the value range of intraratercorrelation coefficient of xing1and xing2is0.6439~0.8105, the repeatabilityis fair to excellent. The values of interrater correlation coefficient（xing1andwang; xing2and wang）also show that the repeatability is fair to excellent, butthe reliability is lower, they are0.5461~0.6419and0.5299~0.7531respectively.Conclusion: The ANOVA analysis show that the CV of BOLD signal ofdifferent areas between begin and malignant tumor had significantlydifference. Central CV of malignant tumor is higher than the peripheral, but inthe benign tumor, it does not show different. The result shows that BOLDcould detect the spontaneous blood flow fluctuations in the tumor. The featureof blood flow fluctuation in different zones in the malignant or benign tumoris related to the blood model and the pathophysiology of the tumor. Thesevessels in the periphery area of malignant tumor has smooth muscle, they aremature and give rich blood supply. However, the neovascularization lackingthe smooth muscle is immature in central zone, blood supply is poor. Thevasomotion in the periphery area of malignant tumor is better than centralzone, and the blood supply is more, the fluctuation of blood flow in theperiphery zone is more obvious than center. In the benign tumor, the vascularbetween the periphery and the central area has no obvious difference, thevessels are mature because of having smooth muscle. The fluctuation of bloodflow between central and periphery zone of benign tumor has no significantdifference. BOLD, which is noninvasive and has high time resolution as a newmethod, can display the different characteristics of blood flow fluctuationbetween benign and malignant tumor, so as to identify them.