Pritumoral Brain Edema Of Intracranial Astrocytoma:evaluation With CTP And DTI

Part one Comparative study of peritumoral brain edema of high- and low-grade astrocytoma with CTPObjective: To observe the difference of CTP parameter of peritumoral brain edema(PTBE) between high- and low-grade intracranial astrocytoma,and to explore the value of CTP on discriminating high- and low-grade astrocytoma.Methods: Thirty cases of intracranial astrocytoma,which proven by surgery and pathologic examination,including 10 cases of low-grade tumors(WHO grade I and II) and 20 cases of high-grade tumors,were retrospectively analysed.Plain CT,postcontrast CT and CTP were made for all patients. We mearsured the CTP parameters,including CBF,CBV,MTT and PS at edema area with a distant of 1cm to the margin of enhancement.Paired t test was made for comparison of the CTP parameters of high- and low-grade astrocytoma with the software SPSS17.0.And the pathologic findings of PTBE was observed with referring CTP images.Result: The value of CBF,CBV,MTT and PS of PTBE of high- grade astrocytoma were higher than those of low-grade astrocytoma.The CBF,CBV,MTT and PS of PTBE of high-grade astrocytoma were(50.05±14.05)ml·min-1·100g-1,(3.50±1.79)ml·100g-1,(5.84±2.95)s and(1.23±1.75)ml·min-1·100g-1 respectively.And CBF,CBV,MTT and PS of PTBE of low-grade astrocytoma were ( 25.20±8.67 ) ml·min-1·100g-1,(1.61±0.68)ml·100g-1,(4.83±1.63)s and(0.33±0.27)ml·min-1·100g-1 separately.There was significant difference of CBF and CBV between high- and low-grade astrocytoma(P<0.05).But no obvious difference was found for MTT and PS between high- and low-grade astrocytoma (P>0.05). Discrete tumor cells was detected in PTBE for both high- and low-grade astrocytoma.Whereas more neoplastic cells were found in PTBE of high-grade astrocytoma.Conclusion: Because of different pathologic findings,there was significant distinction between high- and low-grade astrocytoma.Part two Comparative study of PTBE of high- and low-grade intracranial astrocytomas with DTIObjective: To probe the characteristics of diffusion tensor imaging(DTI) of PTBE of high-and low-grade intracranial astrocytomas and to evaluate the value of DTI in discramination between them. Methods: Fourty cases with brain astrocytoma, including 13cases with low-grade astrocytomas (WHO grade, I~IIgrade) and 27 cases with high-grade astrocytoma (WHO grade, III~IVgrade) were retrospectively analyzed.The diagnosis of these cases was confirmed by surgery and pathology. All patients underwent preoperative conventional MRI scan, postcontrast MRI and DTI. The average diffusion coefficient (ADC) and fractional anisotropy (FA) were measured with region of interesting (ROI) 1cm distal to the edege of enhancement of tumors and the mirror region.Independent-samples t test was used to compare the DTI parameters of PTBE between high-and low-grade astrocytoma, and between the PTBE and the mirror area with the statistical software package SPSS 17.0.Result: The ADC value of PTBE of high-grade astrocytoma [(1.73±0.05)×10-3mm2/s] was higher than that of of low-grade astrocytoma [(1.50±0.07)×10-3 mm2/s] (P<0.0001). FA value of PTBE of high-grade astrocytoma(0.13±0.01) is lower than that of low-grade group of astrocytoma(0.18±0.03) (P<0.0001).The ADC value of PTBE of high-grade astrocytoma[(1.73±0.05)×10-3 mm2/s] is higher than that of the mirror parenchyma[(1.36±0.06)×10-3 mm2/s].While the FA of PTBE of high-grade astrocytoma is lower than that of the mirror parenchyma (0.67±0.12) ( P<0.0001).Conclusion: There is significant difference between the ADC and FA values of PTBE of high- and low-grade astrocytoma .Measurement of DTI parameters of PTBE of the tumor will help to differentiate high-grade astrocytoma from low-grade ones.Part three Discrimination of PTBE of recurrentof astrocytoma and purely postoperative edema with CTPObjective: To probe the value of CTP in differentiating recurrent of astrocytomas and purely postoperative edema.Methods: Tewenty-five cases of brain astrocytoma which confirmed by surgery and pathology,underwent CTP.These patients included low-grade astrocytoma (WHO grade,I~Ⅱgrade) (n=7) and high-grade astrocytoma (WHO grade,III~IVgrade)( n=18) .CTP was performed 20 days to 2.5 years after sugery.The recurrence of tumor was confirmed by secondary operation or newly enhanced lesions or enlargement of enhanced lesions and edema or seconadry space-occuping signs,or exacerbation of clinical amnifestation. CTP parameters, including cerebral blood flow(CBF), cerebral blood volume(CBV), mean transit time(MTT) and permeability surface(PS) values,were measured at edematous region 1cm distal to the edege of tumor or surrounding parenchyma.We compare the difference of CTP parameters between post-operative edema and the edema of recurrence of tumor with independent-samples t test using software of SPSS 17.0.Result: Twenty-five patients included recurrence group(n=11) and purely postoperative edema(n=14).CBF,CBV, and PS of recurrent group were (64.89±9.06)ml·min-1·100g-1,(3.75±1.30)ml·100g-1,(2.32±2.17)ml·min-1·100g-1 separately.Whereas the value of CBF,CBV, and PS of purely postoperative edema group were (18.25±5.63)ml·min-1·100g-1,(1.32±0.44)ml·100g-1 and (1.35±1.72) ml·min-1·100g-1 respectively. There was significant difference of CBF and CBV between the two groups(P<0.05).Although the value of MTT of recurrent group(4.50±1.72s) was lower than that of purely postoperative group (6.37±3.11s),there was no significant difference between them (P=0.089).The sensitivity,specificity,positive predictive value, negative predictive value were 81.8%,78.6%,75.0% and 84.6% separately when using CBV threshold of 2.90 ml·100g-1.Conclusion: The CTP parameters,especially CBF and CBV,will play certain role in differentiating purely postoperative edema and recurrence of intracrainal astrocytomas after operation.