| Objective: To use a new method of quantifying absolute cerebral blood flow (CBF) at 3.0T MRI which has a great deal of improvement in signal-to-noise ratio, and discuss the clinical significations of CBF obtained from FAIR perfusion imaging in classifying brain tumors and studying peritumoral edema.Method: Eight healthy volunteers and thirty-one patients with intracranial lesions were examined at a clinical 3.0T imaging unit. Of the patients with brain tumors, there were eighteen cases of histologically proven gliomas, which were ten high-grade gliomas and eight low-grade gliomas respectively, ten meningiomas, two brain metastases and one brain lymphoma. All of cases obtained FAIR and EPI imagings after general scanning. Furthermore, contrast-enhanced scanning was performed for all of the patients with brain tumors after conventional scanning. Finally, mean tumor blood flow(TBF),maximum tumor blood flow(TBFMAX) and cerebral blood flow of peritumoral edema(PECBF) obtained from the regions of interest in the relative CBF maps were calculated with related formulas, then three normalized relative TBF ratio (TBFN, TBFMAXN, PECBFN)were obtained by making TBF, TBFMAX and PECBF divided by mean CBF of cerebral hemisphere respectively. Statistical analysis was made by using SAS to perform differential test and correlation analysis.Results: All of the cases were obtained clear relative CBF maps. In the volunteers, different cerebral blood flows of gray and white matter determined with FAIR were clearly observed, the CBF of gray matter is obviously higher than that of white matter. Asymmetric perfusion abnormality were observed in all tumor regions of eighteen brain glioma cases; Compared with gliomas, the enhanced signal was symmetrical in meningiomas, and regions of unusually high perfusion were observed. In addition, the TBF of two brain metastases were also higher than the normal performed white matter and gray matter, and their CBF of peritumoral edema reduced obviously.In volunteers, the CBF of white matter and gray matter were measured as 32.0±15.6 and 80.6±31.2ml/100g/min (Mean±SD),respectively. The mean of gray and white matter ratio was 2.7±1.1.In gliomas, TBF of high-grade and low-grade ranged from 42.4 to 179.2 ml/100g/min (mean 112.8, SD 43.2) and ranged from 5.1 to 60.4ml/100g/min (mean 29.4, SD 22.0), respectively. TBFMAX of high-grade and low-grade ranged from 48.6 to 157.5ml/100g/min (mean 118.0, SD 35.8) and ranged from 7.4 to 60.1ml/100g/min (mean 38.2, SD 21.3), respectively. All but one high-grade gliomas showed TBF and TBFMAX >60 ml/100g/min, and all low-grade gliomas showed TBF and TBFMAX≤60ml/100g/min. All but two high-grade gliomas showed TBFN (mean 1.49) and TBFMAXN (mean 1.44)>1, and all but two low-grade gliomas showed TBFN (mean 0.58)and TBFMAXN(mean 0.74)<1. The PECBF and PECBFN of high-grade glioma (mean±SD 26.8±17.8, mean 0.34) and low-grade glioma (mean±SD 26.2±9.7, mean 0.42) were lower than contralateral mirrored normally performed regions.Statistical analysis demonstrated that high-grade and low-grade gliomas differed significantly (P<0.05) in terms of TBF, TBFMAX, TBFN and TBFMAXN, and there was a positive correlation between the pathological grading and the above four measured statistical parameters. Both PECBF and PECBFN had no significant difference between high-grade and low-grade gliomas (P>0.05). Furthermore, the peritumoral edema of gliomas showed higher perfusion than of meningiomasin both in absolute CBF and relative CBF(P<0.05).Conclusion: By quantifying the CBF of the volunteers and tumor sufferers, it proves that it is feasible to quantify absolute cerebral blood flow by FAIR perfusion imaging technology, and FAIR technology is a suitable and safe method which has high applicative values for assessment of tumorous grading before performing surgery.
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