Q.All are true regarding tumour except
a. WHO grade II oligodendrogliomas have significantly higher rCBV than WHO grade II astrocytomas
b. rCBV measurements significantly increased the sensitivity and positive predictive value of conventional MR imaging in glioma grading
c. In radiation necrosis, the enhancing lesion has a lower rCBV than recurrent tumour
d. ADC measurements of the enhancing components in recurrent tumour are significantly lower than in radiation necrosis
e. peritumoural regions in metastases show increase in rCBV or decrease in FA
ANS.----e
The peritumoural regions of high-grade gliomas show a more marked decrease in ADC, fractional anisotropy and NAA and increase in rCBV compared to low-grade tumours. This is a reflection of the more invasive nature of these tumours, which infiltrate the adjacent brain tissue along vascular channels, leading to an rCBV increase; destroy ultrastructural boundaries with a consequent decrease in ADC and FA; and replace normal brain tissue, resulting in a drop of NAA. Metastases on the other hand are surrounded by ‘pure’ vasogenic oedema, which contains no infiltrating tumour cells. These peritumoural regions in metastases therefore show no increase in rCBV or decrease in FA.
a. WHO grade II oligodendrogliomas have significantly higher rCBV than WHO grade II astrocytomas
b. rCBV measurements significantly increased the sensitivity and positive predictive value of conventional MR imaging in glioma grading
c. In radiation necrosis, the enhancing lesion has a lower rCBV than recurrent tumour
d. ADC measurements of the enhancing components in recurrent tumour are significantly lower than in radiation necrosis
e. peritumoural regions in metastases show increase in rCBV or decrease in FA
ANS.----e
The peritumoural regions of high-grade gliomas show a more marked decrease in ADC, fractional anisotropy and NAA and increase in rCBV compared to low-grade tumours. This is a reflection of the more invasive nature of these tumours, which infiltrate the adjacent brain tissue along vascular channels, leading to an rCBV increase; destroy ultrastructural boundaries with a consequent decrease in ADC and FA; and replace normal brain tissue, resulting in a drop of NAA. Metastases on the other hand are surrounded by ‘pure’ vasogenic oedema, which contains no infiltrating tumour cells. These peritumoural regions in metastases therefore show no increase in rCBV or decrease in FA.
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