Oral Exam - CNS Flashcards

Question

Brain abscess/encepahlaitis findings

Answer 1

• PET ○ Abscess – Focal CNSinfection (bacterial,fungal,parasitic etiologies) □ Usually:Peripheral hypermetabolism with central hypometabolism on F-18 FDG PET/CT – Toxoplasmagondii □ Common opportunistic infection in HIV/AIDS patients □ Toxoplasmosis is hypometabolic on F-18 FDG PET/CT □ Lymphoma is hypermetabolic on F-18 FDG PET/CT ○ Encephalitis – CNS inflammation; most common etiology is viral (e.g., herpes simplex encephalitis) □ Acute: Hypermetabolism on F-18 FDG PET/CT □ Subacute: May be isointense to gray matter on F-18 FDG PET/CT □ Chronic,nonactive:HypometaboliconF-18FDG PET/CT

Answer 2

Herpes simplex virus type 1 (HSV-1) ○ Medial temporal and inferior frontal lobes; cingulate gyrus and contralateral temporal lobe highly suggestive ○ Limbic system most typically (temporal lobes, insula, subfrontal, cingulate gyri)

Answer 3

Chronic, unilateral brain inflammation; etiology unclear ○ Unilateral cerebral atrophy – Initiallyfocalinvolvement,thenhemispheric – Whenhemispheric,worseprecentralandinferior frontal

Answer 4

• Limbic encephalitis ○ Rare paraneoplastic syndrome associated with primary tumor, often lung ○ Imaging may be indistinguishable from herpes simplex encephalitis on MR and F-18 FDG PET/CT ○ Subacute symptom onset (weeks to months) vs. acute in herpes simplex encephalitis

Answer 5

○ DopaminetransporterSPECT(I-123FP-CIT) – dopamine transporters located on presynaptic nigrostriatal axons in putamen and caudate nucleus – I-123 FP-CIT confirms loss of dopaminergic neurons – Sensitivity > 90% for differentiating PD and essential tremor Differentiates PD and APS from essential tremor and drug-induced parkinsonism – Does not differentiate PD from APS or between APSs ○ F-18FDGPET/CT – TypicallynormalinPD □ Preserved F-18FDGPET/CT in basalganglia differentiates PD from parkinsonian syndromes

Answer 6

○ Parkinsonism,ataxia,and autonomic dysfunction – Cerebellar dominant(MSA-C) and parkinsonian dominant (MSA-P) ○ F-18FDGPET – MSA-P shows decreased putamen activity – MSA-C shows decreased activity in cerebellum ○ Amyloid PET negative ○ I-123FP-CITSPECTpositive

Answer 7

``` ○ F-18FDGPET/CT – Decreased F-18FDG activity in basal ganglia, frontal lobes, anterior cingulate, midbrain ○ Amyloid PET negative ○ Ioflupane SPECT positive ```

Answer 8

``` akinesia,rigidity,dystonia,apraxia, executive dysfunction, aphasia ○ Patientsdonotrespondtolevodopa ○ F-18FDGPET/CT – Relative decreased activity in contralateral cortexand basal ganglia ○ AmyloidPETnegative ○ I-123 FP-CIT SPECT positive, typically asymmetric and decreased contralateral to symptoms ```

Answer 9

1. Atypical parkinsonian syndromes 2. Benign essential tremor 3. Vascular parkinsonism 4. Drug induced

Answer 10

• Imaging may confirm brain death but does not substitute for clinical criteria Brain parenchyma scintigraphy ○ Tc-99mexametazime(HMPAO),Tc-99methylcysteinate dimer (ECD) ○ Tc-99mHMPAO preferred since it accumulates in brain parenchyma within 2 min and takes several hrs before significant redistribution ○ Absentcerebraluptake – Nouptakeinallportionsofbrain – Hotnosesign □ Early increased activity in nasopharyngeal region on anterior view • Brainnuclearangiogram ○ Flow radiotracers: Tc-99mDTPA or Tc-99m pertechnetate ○ Only allows assessment of anterior brain circulation ○ Requires good bolus technique and adequate cardiac output

Answer 11

– Angiographic phase □ Trident sign: Early simultaneous visualization of the paired anterior cerebral arteries (ACAs) and each middle cerebral artery (MCA) – Blood pool phase □ Visualization of venous sinuses but not brain ○ Absent cerebral perfusion – Angiographic phase □ Absence of trident; empty lightbulb sign; hotnose sign – Bloodpool phase □ Delayed images may visualize venous sinuses from centrally draining scalp perforators □ Lack of superior sagittal sinus activity helps confirm lack of cerebral perfusion

Answer 12

○ Dose – Brain parenchyma: 15-20mCi (555-740MBq) for adults; 0.3 mCi/kg for children – Brain bloodflow: Up to 30mCi(1.1GBq) ○ Image acquisition – Gamma camera with field of view large enough to image entire head and neck – Flowimages □ Brainparenchyma:Imageacquisitionstartingat time of radiotracer injection and ending well after venous phase □ 1-3 sec per frame for at least 60 sec □ Brainangiogram: Tracer flow should be observed from level of carotids to skull vertex – Static planar images □ Brainparenchyma:Anteriorandlateralplanarviews should be obtained after at least 20 min – SPECT □ May be obtained in addition to flow and planar images with brain parenchyma tracers □ Allowsbettervisualizationofperfusiontoposterior fossa and brainstem structures ○ Reporting recommendations – Cerebral and cerebellar perfusion absent – Cerebral and cerebellar perfusion present – Cerebralandcerebellarperfusionpresent,although abnormal (discuss specific regions of uptake/lack of uptake)

Answer 13

``` Infarct Cyst Necrotic tumour Hematoma Abscess Previous irradiation ```

Answer 14

Ictal seizure focus | Encephalitis

Answer 15

Atrophy Infarct Inter-ictal seizure focus Low grade tumour

Answer 16

Decreased metabolism in BG

Answer 17

Decreased perfusion with acetazolamide to most of the hemisphere

Oral Exam - CNS Flashcards

(41 cards)