L4 Radiology of the CNS PDF Lecture Notes

Radiology of the Central Nervous System Slides by Jeff Chesnut, DO John Gassler DPT DOSYS 725 Medical Neuroanatomy II Lecture 4 January 14, 2025 Objectives By the end of this lecture the student should be able to: 1. Differentiate between the properties of the vario...

Radiology of the Central Nervous System Slides by Jeff Chesnut, DO John Gassler DPT DOSYS 725 Medical Neuroanatomy II Lecture 4 January 14, 2025 Objectives By the end of this lecture the student should be able to: 1. Differentiate between the properties of the various radiologic imaging studies for brain imaging and spine imaging and determine the appropriate study to order for various conditions 2. Identify the structures discussed in this lecture on axial CT and/or MRI Case A 63-year-old woman presents to the emergency department two hours following onset of left facial numbness and facial droop. She is also found to have decreased muscle strength in her left arm and leg, as well as numbness and tingling in the same distribution. She is having difficulty speaking. What imaging should we obtain and where might we predict a lesion? Imaging Modalities of the Brain Skull radiographs Skull radiography should NEVER be used as a sole imaging modality in the setting of trauma Poor correlation between skull fractures and intracranial pathology May be used for craniosynostosis evaluation, but CT is probably a better choice Ultrasound May be very useful in infants Open fontanelles create “acoustic window” through which imaging can be performed Limited usefulness in adults Skull limits the available acoustic windows Thin bone in temporal region and window at the cisterna magna can be used for limited purposes (eg – detecting midline shift) Doppler transcranial ultrasound may detect presence/absence of flow in MCA US is highly useful in evaluating extracranial carotid artery and (to a lesser extent) vertebral artery flow Germinal matrix bleed in premature infant Nuclear medicine In-111 DTPA cisternography (non-communicating hydrocephalus) Intrathecal radionuclide injection may be used to differentiate communicating from non- communicating hydrocephalus Evaluation of CSF leak Assessment of shunt patency Normal Tc-99m DTPA shunt scintigram Assessment of cerebral blood flow (brain death study) Normal Tc-99m HMPAO cerebral Tc-99m HMPAO cerebral perfusion scintigram (with abnormal perfusion scintigram with no absent cerebellar perfusion) effective cerebral perfusion SPECT and PET imaging (nuclear medicine) Brain SPECT and Positron emission tomography (PET) may be used for perfusion imaging and dementia evaluation Much research being done on brain imaging in dementia and mental illness CT vs. MRI of the Brain CT scan MRI Fast, less expensive, readily Slower, more expensive, less available readily available Any stable patient Exclusionary criteria Less definition of brain structures Better definition of brain structures (but better for osseous structures) Edema is well visualized Edema is less well seen Minimally less sensitive for acute Sensitive for acute bleeds if done bleeds without contrast. Non-acute pathology (symptoms > Best for acute pathology 48 hrs.) (symptoms < 48 hrs.) CT vs. MRI in stroke Patient A Non-enhanced CT scan Diffusion weighted MRI Patient B Non-enhanced CT scan Diffusion weighted MRI CT is the preferred imaging modality in acute stroke. Why? In a stroke, time = brain. Our goal is to get a pt. having an acute stroke thrombolytics as soon as possible, preferably within 60 min. after pt. arrival We need to make sure the patient doesn’t have intracranial bleed BEFORE we start on thrombolytics. CT is perfectly adequate for this CT is much quicker than MRI (15 sec. vs. 40 min.) Case A 63-year-old woman presents two hours following onset of left facial numbness and facial droop. She is also found to have decreased muscle strength in her left arm and leg, as well as numbness and tingling in the same distribution. She is having difficulty speaking. What imaging should we obtain and where might we predict a lesion? CT scan without contrast Basic Brain Imaging Anatomy Viewing axial imaging Ant Right Left Post Level of medulla Maxillary sinus Temporal lobe Infundibular (pituitary) stalk Sella turcica Medulla oblongata Cerebellum Cerebellar vermis CT scan T1-weighted MRI Level of the pons Eye with retroconal fat, medial rectus and lat rectus ms. Frontal lobe Sphenoid sinus Suprasellar cistern Temporal lobe Cerebello-pontine (CP) angle Pons 4th ventricle Cerebellum Occipital lobe CT T1-weighted MRI Level of the Midbrain Frontal lobe Lateral ventricle (frontal horn) 3rd ventricle Temporal lobe Midbrain Cerebral aqueduct Quadrigeminal cistern Cerebellar vermis Occipital lobe CT T1-weighted MRI Level of the thalamus Interventricular foramen (of Monro) Head of caudate Ant. Limb of int. capsule Globus pallidus/putamen Insula Lateral fissure Post. Limb of internal capsule Thalamus Pineal gland Parieto-occipital lobe Choroid plexus in occipital CT horns of lateral ventricle T1-weighted MRI Level of the caudate Superior sagittal sinus Corona radiata Caudate nucleus Lateral ventricle CT T1-weighted MRI Supraventricular brain Falx cerebri Centrum semiovale (deep white matter) CT T1-weighted MRI Ventricular system of the brain Cerebral Lateral ventricle aqueduct (of Sylvius) Intraventricular foramen (of Monro) Third ventricle Fourth ventricle Ventricular system of the brain Frontal horns of the lateral ventricles Interventricular foramen Third ventricle Occipital horns of lateral ventricle Axial T2 weighted MRI Coronal T1 weighted MRI Ventricular system of the brain Fourth ventricle T2 weighted axial MRI T2 weighted coronal MRI Ventricular system of the brain (Midbrain) Cerebral aqueduct Arterial Supply of the Brain Circle of Willis Ant. Cerebral a. (A2) Ant. Comm. A. Ant. Comm. A. Ant. Cerebral a. (A1) Internal carotid a. Middle cerebral a. Post. Comm. art Middle Posterior cerebral cerebral a. a. Basilar a. Vertebral a. We can predict which artery is obstructed by the distribution of the infarct (You do NOT need to know these vascular territories for the exam) A 63-year-old woman presents two hours following onset of left facial numbness and facial droop. She is also found to have decreased muscle strength in her left arm and leg, as well as numbness and tingling in the same distribution. She is having difficulty speaking. What imaging should we obtain and where might we predict a lesion? What artery is likely to be involved? Right hyperdense MCA sign (thrombosis) Right MCA infarct https://radiopaedia.org/cases/right -mca-infarction-teaching CT performed 3 days following infarct Studying for this exam For the anatomic slides, if it doesn’t have an arrow and label, it won’t be on the exam You won’t have to diagnose pathology or know anatomy for any modalities except CT and MRI, but you should know what the various modalities are useful for. For my purposes, you do not need to memorize the arterial territories of the brain Spend a little time reviewing the anatomy of the ventricular system