Monday, 23 May 2016

BRAIN METASTASES

Q.All are true regarding brain metastases except
a. deposits from malignant melanoma hyperdendse on CT
b. Increasing relaxivity of gadolinium compounds improve  detection of metastases
c.Well-differentiated adenocarcinoma metastases are hypointense on trace-weighted DWI,
d.PWI and MRS of  intratumoural region useful  in differentiating single metastasis from a glioma
e.DWI is helpful to differentiate cystic metastasis  from cerebral abscesses
ANS -------d
Metastases are characterized by oedema in the surrounding white matter, which appears dark on trace-weighted DWI and is often disproportionate to the size of the tumour itself.
Increasing the contrast dose or relaxivity of gadolinium compounds can improve the sensitivity for detection of metastases on MRI

Well-differentiated adenocarcinoma metastases are hypointense on trace-weighted DWI, whereas small cell and neuroendocrine metastases are hyperintense, due to their higher cellularity . On standard MRI it may occasionally be difficult to distinguish a single metastasis from a glioma. PWI and MRS of the peritumoural rather than intratumoural region were shown to be useful in differentiating the two.

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