CT of the brain tumors & abdomen

Brain tumors : CT finding Meningioma   Meningioma Benign tumor arise from the arachnid cells of the meningeal covering of the brain are most common primary intracranial neoplasm Usually present in middle age female it is well defined extra axial , located mainly at the convexity of the skull periphery rounded or sessile , plaque like , specially the tumor arise from the cribriform plate , or those arise from the petrus bone , planum spheniodale , or from skeleton of the pituitary fosse .  CT finding meningioma presented as isodense area or slightly hyper density area with surrounded crescent of hypo density ( csf cap ) post contrast injection the lesion enhance homogeneously with enhancing Dural tail . 20 % show calcification hyperostosis & thickening of the near by bony part of the skull & diplioc space . it may be associated with little or no peri focal edema . if the lesion associated with central necrosis with large perifocal edema meningio sarcoma should be excluded .

Glioma Comments primary interracial tumor , vary greatly in malignancy , have many names depending on the histological type grading of malignancy of G. depending on the following : well defined or irregularity of the lesion surrounding edema present or absent associated shifting of midline & crossed midline lesion contrast enhancement associated hemorrhage , necrosis , & cystic formation seeding via csf & dissemination . Low grade G. I well or ill defined lesion iso dence to the brain tissues , not associated with oedeme , no Enhancement , no associated Hemorrhage , necrosis . From G II , III, various previous finding IV( glioblastoma multiforme ) are highly malignant have all previous mentioned features .

Posterior fosse tumor Medullo blastoma Haemangioblastoma Age incidence between 5-15 Y represent about 35-40 %of PFT Arise from the midline mainly within or from the roof of the 4 TH ventricle fill the fourth ventricle & seeding via the csf so can seen in the distal part of the spinal canal . CT finding as well circumscribed lesion heterogeneous in density ,have solid & cystic part , with also scattered calcification little surrounded edema , the solid part is enhance 90 % present with obstructive hydrocephalous at the level of the 4Th V. with dilatation of the lateral V. ( body , frontal , temporal & third ventricle ) 40 % of child have secondary metastasis at the time of presentation Haemangioblastoma Arise from per vascular pericyte GII to III in their malignancy Age between 30 -65 Y , represent 10 % of PFT Intra axial t. arise from the cerebellum , brain stem ,spinal cord CT finding , as smooth walled cystic lesion with enhancing mural nodule rarely calcified .  

Medulloblastoma haemangioblastome notice the dense nodular enhancement

Pilocytic astrocytome Secondary metastasis   Pilocytic astrocytome Present in the childhood 5-15 Y Arise within the vermis & cerebral hemisphere CT finding appear as well circumscribed lesion hypo or hyper dense & growing mainly with expansion , usually large lesion solid or cystic or both of them , with , enhancing mural nodule 20 % show calcification of the nodule , may be associated with edema . Secondary metastasis Old age group above 50 Y , any lesion within the cerebellar hemisphere it is secondary metastasis unless proven otherwise F. from breast CA M. from bronchogenic CA . Appear as nodular single or multiple lesion hypo dense or hyper dense . Surrounded by per focal edema Enhanced as solid or ring pattern of enhancement .

Hydrocephalous 2 types Obstructive ( non – communicating ) Craniophyrengioma Medulloblastoma Ependymoma Aquiduct stenosis , comments cause of obstruction being congenital in nature . Non –obstructive ( communicating ) No obstruction of the ventricular pathway , but the absorption of the csf at the level of arachnoids' granulation is occluded secondary to lodge by blood clot or inflammatory cell or infection post meningitis most commonly to occur post SAH .

Hydatid cyst

Normal CT of the abdomen

CT abdomen Hydatid cyst calcification Appear as large oval hypo dense area density of fluid with well defined margin , sometime at their periphery multiple flecks of calcification are seen at their periphery . Hydatid cyst with daughter cyst , appear as multiple hypo densities rounded area within the main loculi with multiple rim of calcification Secondary metastasis in the liver Multiple rounded hypo density areas of different density , shape & different size . Pattern of enhancement is either uniform , target or bulls eye pattern . Hepato megaly .

Hydatid cyst within the liver

Secondary metastasis within the liver

Pancreatitis Patient present with abdominal pain , vomiting with or without jaundice , increase amylase level CT finding Enlargement of the pancreas focal or generalized increase in size . Hypo density within the pancreas focal or generalized due to the edema . Peri pancreatic fluid collection & edema around the pancreas . The fluid around the pancreas if persist more than 6 w become encysted leading to the pancreatic pseudo cyst any area could be affected . Edema of the wall of the stomach .

Abdomenal aortic aneurysm