Elster’s rule

284..Which dimention is not part of Elster’s rule for maximum 

normal height (in mm) of the  pituitary gland?

a.6mm

b.8mm

c.10mm

d.12mm

e.14mm

284.---e

6mm (infants and children),8mm (men and postmenopausal 

women),10mm(women of child bearing age),12 mm( women in 

late pregnancy or postpartum women) are  maximum normal height

 (in mm) of the  pituitary gland according to Elster’s rule. 

Ependymoma

Q.All are true regarding ependymoma except

a.more tha  90% in fourth ventricle

b.extrudes through outlet foramina

c.spinal seeding relatively  common

d. 50% calcify

e.moslty isodense on NECT

ANS .---c

Spinal seeding is relatively uncommom

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.

INTRAVENTRICULAR LESIONS

Q.All are true regarding intraventricular meningioma except

a. arise from arachnoid cells of the tela choroidea

b. most commonly occur in the lateral ventricles

c. usually appearing in the middle-aged and elderly population

d.have  a smooth margin and are generally oval in configuration

e.difffuse hydrocephalus

ANS .---e

Intraventricular meningiomas can usually be differentiated from choroid plexus papillomas both clinically and with MR. Lateral ventricular choroid plexus papillomas develop mainly in young children, with meningiomas usually appearing in the middle-aged and elderly population. Meningiomas have a smooth margin and are generally oval in configuration  whereas papillomas frequently demonstrate very nodular, heterogeneous, irregular surfaces. Papillomas also usually present with diffuse hydrocephalus and not just dilation of the trapped ventricular segment. This occurs either because of their overproduction of CSF or their frequent bleeding, which may cause obstructing basal arachnoiditis and/or intraventricular ependymitis. Although papillomas are more frequently very heterogeneous, intraventricular meningiomas can also show significant heterogeneity and extensive edema . Therefore, the location of the lesion and the age of the patient are the two most valuable clues to the diagnosis