Imaging of CNS infections

Imaging of CNS infections DR MILI DUTTA protocol  Axial T1W  Axial T2W TURBO  Axial FLAIR/Coronal  Coronal/sag T2W  CE—TIW TIW Same parameter settings pre/post contrast  D MP-RAGE(GRE) –THIN SLICES/ANY PLANE/GOOD GREY WHITE DIFF DWI V SENSITIVE TO VENTRICULITIS  ABSCESS VS TUMOR T2w/flair  Infarct  Edema  Capsular rim  Perivent FLAIR T1w/c  Meningeal  Effusion vs empyema  Choroid plexitis—diff on FLAIR/DWI because BRIGHT intravent contents make it diff to detect  Comparison of MRI Sequences to Detect Ventriculitis AJR 2006; 187:1048-1053 TUBERCULOSIS starts subpial / subependymal cortical focus (Rich focus), GRANOLOMA ERODES INTO SAS LEPTOMENINGITIS OBSTRUCTS FORAMEN LUSHAKA/MAGENDIE— OBSTRUCTIVE HYDROCEPHALUS NON OBS GRANULOMA ABSCESS CEREBRITIS PACHYMENINGITIS VASCULITIS (THALAMOSTR //THALAMOPERFORATE INFARCT CT  CECT leptomeningeal and basal cistern enhancement  EPENDIMITIS- linear perivent enhancement  VENT DIL (eg, third and fourth vent) due to hydrocephalus  low-attenuating focal infarcts deep gray-matter nuclei, deep white matter, -due tovasculitis  Parenchymal cerebritis – hypoatt/ enhancement  Parenchymal tuberculomas Noncaseating granulomas are homogeneously enhancing lesions Caseating granulomas are rim enhancing miliary pattern with multiple tiny nodules scattered throughout the brain All surrounded by hypoattenuating edema MR T1W prominent leptomeningeal and basal cistern enhancement  ependymitis, linear periventricular enhancement  Ventricular dilatation due to hydrocephalus  Deep gray-matter nuclei, deep white matter, and pontine infarctions resulting from vasculitis are hyperintense on T2-weighted images  DWI early ischemic lesions when T2 N The primary differential diagnoses are fungal meningitis, bacterial meningitis, carcinomatous meningitis, and neurosarcoidosis  Parenchymal cerebritis hyperintensity with little or no enhancement on T2-W  tuberculomas hypo/HYPER on T2-weighted images  Noncaseating granulomas homogeneously enhancing// Caseating granulomas are rim enhancing //miliary pattern with multiple tiny, enhancing nodules scattered throughout the brain surrounded by hyperintense edema on T2-weighted images The differential diagnoses include fungal infections, bacterial infections, neurocysticercosis, and cerebral metastases  MRS(single-voxel )TO D/D neoplasms elevated fatty-acid Due to necrosis of the waxy walls of mycobacteria within the granuloma The lactate peak anaerobic glycolysis  INCREASED LACTATE, DECREASED NAA,CHOLINE  Inner wall Satellite lesion Capsule Dwi MRS  Smooth inner wall in abscess  Present in abscess  Hypo capsule of abscess Abscess  Pus is thick mucoid inflamm cells, exudate Bacteria necrotic material Vel is decreased in thick viscous-macro/micro diff Water binds to fibrinogen mass  Necrotic has more serous fluid  Mass with cavity  Enhancement and edema  Hyperintense on DWI >ON DWI (geometric distortion),(restricted diff of capsule) MASS—THIN RIM(??) ENHANCEMENT—HYPO ON DWI ASPERGILLUS  ANGIOINVASIVE-multiple areas of infarct and hemorrhage  Low signal intensity in periphery on T2W - areas of hemorrhage - -presence of iron, manganese, and magnesium in the fungal concretions - dense population of hyphal elements peripherally with a relative paucity of fungal elements centrally LOW SI WITHIN MASSS SLIGHT RIM ENHANCEMENTS HYPER ON T1 MASS –HYPO RIM INCOMPLETE VENTRICULITIS  ependymitis,ventricular empyema, pyocephalus  intraventricular debris and pus - abnormal periventricular - subependymal signal intensitY - enhancement of the ventricular lining CT and MR Imaging Features of Pyogenic Ventriculitis American Journal of Neuroradiology 22:1510-1516 (9 2001  MAY BE CAUSE OF PERSISTENT MENINGITIS  MOSTLY BY GRAM NEG, THEN STAPH MRI VS CT  Detects extra cerebrral collections more easily since free of bony artifacts  d/d purulent Subdural effusion—t1 hyper  Localized enhancement adjacent to sinuses s/o rhinogenous ... include fungal infections, bacterial infections, neurocysticercosis, and cerebral metastases  MRS(single-voxel )TO D/D neoplasms elevated fatty-acid Due to necrosis of the waxy walls of mycobacteria... dependent on stage  Cerebritic stage – thick diffuse ring of enhancement, further diffusion on contrast into central lumen or lack of decay of contrast on delayed scan 30-60 minutes later  Capsular... there is decay of enhancement on delayed scans Multiple abscesses in a year old Subdural Empyema - evaluation  CT of head both with and without contrast  LP - hazardous - risk of transtentorial