Chapter 22
The patient was admitted with a head injury and an intracranial pressure (ICP) monitoring device was placed. The nurse knows to notify the practitioner if what type of wave start to appear on the monitor? a. A waves b. B wave c. C waves d. D waves
ANS: A A waves are the most clinically significant of the three types. They usually occur in an already elevated baseline intracranial pressure (ICP) (>20 mm Hg) and are characterized by sharp increases in ICP of 30 to 69 mm Hg, which plateau for 2 to 20 minutes and then return to baseline. B waves appear to reflect fluctuations in cerebral blood. C waves are small, rhythmic waves that occur every 4 to 8 minutes at normal levels of ICP. They are related to normal fluctuations in respiration and systemic arterial pressure.
A patient is admitted to the critical care unit with a subdural hematoma. The nurse is assessing the patient's Glasgow Coma Scale (GCS) score. When assessing the patient's best motor response, which movement would receive the lowest score? a. Abnormal extension b. Localizing pain c. Withdrawing from pain d. Decorticate posturing
ANS: A Abnormal extension (decerebrate posturing) receives a score of 2 on the Glasgow Coma Scale (GCS). The only lower score is 1, which is for a flaccid response.
The nurse is caring for a patient who has sustained a traumatic head injury. The practitioner has asked the nurse to test the patient's oculocephalic reflex. What must the nurse verity prior to performing the test? a. The absence of cervical injury b. The depth and rate of respiration c. The patient's ability to swallow d. The patient's ability to follow a verbal command
ANS: A In an unconscious patient, assessment of ocular function and innervation of the medial longitudinal fasciculus (MLF) is performed by eliciting the doll's eyes reflex. If the patient is unconscious as a result of trauma, the nurse must ascertain the absence of cervical injury before performing this examination.
A patient is undergoing a preoperative evaluation for carotid arteries. What two test should the nurse expect to see ordered for the patient? a. Ultrasound and magnetic resonance angiography b. Conventional angiography and evoked potential c. Computed tomography (CT) and magnetic resonance angiography d. Transcranial Doppler and extracranial Doppler
ANS: A Magnetic resonance angiography of the carotid arteries has become an established complement to preoperative ultrasound evaluation. It helps determine the area of salvageable tissue (or penumbra) after acute stroke and head injury.
The nurse knows that change in pupil size is a significant neurologic finding particularly in the patient with a head injury. How much of a size difference between the two pupils is still considered normal? a. 1 mm b. 1.5 mm c. 2 mm d. 2.5 mm
ANS: A Pupil size should be documented in millimeters with the use of a pupil gauge to reduce the subjectivity of description. Most people have pupils of equal size, between 2 and 5 mm. A discrepancy up to 1 mm between the two pupils is normal.
A patient is admitted to the critical care unit with a subdural hematoma. The nurse is assessing the patient's Glasgow Coma Scale (GCS) score. Which statement is true concerning the GCS? a. It provides data about level of consciousness only. b. It is considered equivalent to a complete neurologic examination. c. It is a sensitive tool for evaluation of an altered sensorium. d. It is the most critical assessment parameter to account for possible aphasia.
ANS: A Several points should be kept in mind when the Glasgow Coma Scale is used for serial assessment. It provides data about level of consciousness only, and it should never be considered a complete neurologic examination. Additionally, it is not a sensitive tool for evaluation of an altered sensorium, and it does not account for possible aphasia or mechanical intubation. It is also a poor indicator of lateralization of neurologic deterioration.
Which of the following statements best describes assessment of arousal? a. It measures content of consciousness and is a higher-level function. b. It is an evaluation of the reticular activating system and its connection with the thalamus and the cerebral cortex. c. It becomes a valid parameter when the patient is able to respond to verbal stimuli, such as squeezing the hands on command. d. Noxious stimuli are not to be used as an assessment parameter.
ANS: B Assessment of the arousal component of consciousness is an evaluation of the reticular activating system and its connection with the thalamus and the cerebral cortex. Arousal is the lowest level of consciousness, and observation centers on the patient's ability to respond to verbal or noxious stimuli in an appropriate manner.
The nurse is caring for a severely head injured comatose patient who is dying. The nurse knows the patient has entered the late stages of intracranial hypertension when the nurse observes which signs? a. Pupils are equal and reactive b. Widening pulse pressure c. Eupnea d. Decreased intracranial pressure
ANS: B Attention must also be paid to the pulse pressure because widening of this value may occur in the late stages of intracranial hypertension. With the loss of autoregulation as blood pressure increases, cerebral blood flow (CBF) and cerebral blood volume increase and intracranial pressure (ICP) therefore increases. The mean arterial pressure must be maintained at a level sufficient to produce adequate CBF in the presence of elevated ICP.
The nurse is caring for a critically injured patient who can only be aroused by vigorous external stimuli. Which category should the nurse use to document the patient's level of consciousness? a. Lethargic b. Obtunded c. Stuporous d. Comatose
ANS: C Stuporous means the patient can be aroused only by vigorous and continuous external stimuli. Motor response is often withdrawal or localizing to stimulus. Obtunded means the patient displays dull indifference to external stimuli, and response is minimally maintained. Questions are answered with a minimal response. Lethargic means the patient displays a state of drowsiness or inaction in which the patient needs an increased stimulus to be awakened. Comatose means vigorous stimulation fails to produce any voluntary neural response in the patient.
According to the 2007 Brain Trauma Foundation guidelines, the recommended CPP range is: a. 10 to 30 mm Hg. b. 30 to 50 mm Hg. c. 50 to 70 mm Hg. d. 70 to 85 mm Hg.
ANS: C The 2007 Brain Trauma Foundation guidelines now recommend a cerebral perfusion pressure (CPP) in the range of 50 to 70 mm Hg and consideration of cerebral autoregulation status when selecting a CPP target in a specific patient.
The nurse is caring for a patient with an intracranial pressure-monitoring device that provides access to cerebrospinal fluid (CSF) for sampling. What type of device does the patient have? a. Subarachnoid bolt b. Epidural catheter c. Intraventricular catheter d. Fiber-optic catheter
ANS: C An intraventricular catheter allows accurate intracranial pressure (ICP) measurement and provides access to cerebrospinal fluid (CSF) for drainage or sampling. A subarachnoid bolt, epidural catheter, and fiber-optic catheter provide no access for CSF sampling.
A patient is going for digital subtraction angiography. The patient education plan to prepare the patient for the procedure should include which instruction? a. Inform the patient that the procedure is very noisy and earplugs will be provided b. Tell the patient that repositioning will be required at appropriate intervals c. Instruct the patient to remaining motionless during the entire procedure d. Let the patient know he will be expected to swallow frequently during the procedure
ANS: C The major disadvantage of digital subtraction angiography involves the patient's ability to remain motionless during the entire procedure. Even swallowing significantly interferes with the imaging process.
A patient has been admitted with acute confusion and other focal neurologic signs. The practitioner is going to perform a lumbar puncture. What is the most serious complication of lumbar puncture? a. Meningitis b. Dural tear c. Brainstem herniation d. Spinal cord trauma
ANS: C Two life-threatening risks associated with lumbar puncture include possible brainstem herniation, if intracranial pressure is elevated, and respiratory arrest associated with neurologic deterioration.
A patient is admitted with an anoxic brain injury. The nurse notes abnormal extension of both extremities to noxious stimuli. This finding indicates dysfunction in which area of the central nervous system? a. Cerebral cortex b. Thalamus c. Cerebellum d. Brainstem
ANS: D Abnormal extension occurs with lesions in the area of the brainstem. Abnormal flexion occurs with lesions above the midbrain in the region of the thalamus or cerebral hemispheres.
The nursing is caring for a comatose patient with a brain tumor. When the nurse touches the palm of the patient's hand, the patient grasps the nurse's hand. What is this sign indicative of? a. There is damage to the brainstem. b. It's a normal finding. c. The patient is getting better. d. Cortical damage is present.
ANS: D The grasp reflex is present when tactile stimulation of the palm of the hand produces a grasp response that is not a conscious voluntary act. The grasp reflex is a primitive reflex that normally disappears with maturational development; thus, the presence of the grasp reflex in the adult indicates cortical damage.
The nurse is caring for a patient with a head injury who is obtunded. The nurse is going to use noxious stimuli to elicit a response. What is an acceptable method? a. Nipple pinch b. Nail bed pressure c. Supraorbital pressure d. Sternal rub
Nail bed pressure and trapezius pinch are acceptable methods of noxious stimulation. Nail bed pressure allows evaluation of individual extremity function. Trapezius pinch is difficult to perform on large or obese adults. Repeated sternal rub can cause the sternum to become excoriated, open, and infected. Supraorbital pressure must be avoided in patients with head injuries, frontal craniotomies, or facial surgery. Nipple and testicle pinching are inappropriate and unnecessary.
The nurse is caring for a patient who has just had a cerebral angiogram. Which intervention should be part of the nursing management plan? a. Ensuring that the patient is adequately hydrated b. Maintaining the patient on an NPO status c. Administering antibiotics to the patient d. Keeping the patient flat in bed for 24 hours
ANS: A After the cerebral angiogram, adequate hydration is necessary to assist the kidneys in clearing the heavy dye load. Inadequate hydration may lead to renal dysfunction and renal shutdown.
A critical care patient is diagnosed with massive head trauma. The patient is receiving brain tissue oxygen pressure (PbtO2) monitoring. The nurse recognized that the goal of this treatment is to maintain PbtO2: a. greater than 20 mm Hg. b. less than 15 mm Hg. c. between 15 and 20 mm Hg. d. between 10 and 20 mm Hg.
ANS: A In a patient with head injury, the goal of treatment is to maintain the PbtO2 greater than 20 mm Hg. Factors that decrease PbtO2 include tissue hypoxia, hypocapnia, hypovolemia, decreased blood pressure, low hemoglobin levels, intracranial hypertension, and hyperthermia. Treatment is directed at the underlying cause.
The nurse is caring for a severely head injured comatose patient who is dying. The practitioner asks to be notified when the patient starts to exhibit signs of Cushing reflex. The nurse would call the practitioner when the patient starts to show what signs? a. Bradycardia, systolic hypertension, and widening pulse pressure b. Tachycardia, systolic hypotension, and tachypnea c. Headache, nuchal rigidity, and hyperthermia d. Bradycardia, aphasia, and visual field disturbances
ANS: A The Cushing reflex is a set of three clinical manifestations (bradycardia, systolic hypertension, and widening pulse pressure) related to pressure on the medullary area of the brainstem.
Which patient may need sedation before having a magnetic resonance imaging (MRI) scan? a. Claustrophobic patient b. Comatose patient c. Elderly patient d. Patient with a spinal cord injury
ANS: A The magnetic resonance imaging procedure is lengthy and requires the patient to lie motionless in a tight, enclosed space. Mild sedation, a blindfold, or both may be necessary for claustrophobic patients.
Considering anatomic location, which cranial nerve will be affected first by downward pressure onto the infratentorial structures? a. III b. VI c. IX d. X
ANS: A With the location of the oculomotor nerve (cranial nerve [CN] III) at the notch of the tentorium, pupil size and reactivity play a key role in the physical assessment of intracranial pressure changes and herniation syndromes. In addition to CN III compression, changes in pupil size occur for other reasons. Large pupils can result from the instillation of cycloplegic agents, such as atropine or scopolamine, or can indicate extreme stress. Extremely small pupils can indicate narcotic overdose, lower brainstem compression, or bilateral damage to the pons.
Which procedure is the diagnostic study of choice for acute head injury? a. Magnetic resonance imaging b. Computed tomography c. Transcranial Doppler d. Electroencephalography
ANS: B Computed tomography offers rapid, convenient, noninvasive visualization of structures and is the diagnostic study of choice for an acute head injury.
The nurse is precepting a nursing student. The student asks about testing of extraocular eye movements. What should the nurse tell the student? a. It tests the pupillary response to light. b. It tests function of the three cranial nerves. c. It tests the ability of the eyes to accommodate to a closer moving object. d. It tests the oculocephalic reflex.
ANS: B Control of eye movements occurs with interaction of three cranial nerves: oculomotor (III), trochlear (IV), and abducens (VI).
The patient is ordered a computed tomography (CT) scan with contrast. Which question should the nurse ask the conscious patient before the procedure? a. "Are you allergic to penicillin?" b. "Are you allergic to iodine-based dye?" c. "Are you allergic to latex?" d. "Are you allergic to eggs?"
ANS: B If the patient is scheduled to receive contrast for computed tomography (CT) scanning, questions about possible sensitivity to iodine-based dye must be asked beforehand, if possible. During infusion of the dye and for 10 to 30 minutes afterward, the patient is observed closely for an anaphylactic reaction. Fewer than 1% of all patients undergoing contrast-enhanced CT have severe anaphylactic reactions, shock, or cardiac arrest.
A patient has been admitted with acute confusion and other focal neurologic signs. The practitioner orders magnetic resonance imaging (MRI). The nurse knows in certain situations an MRI is superior to computed tomography (CT). What is one those situations? a. Brain death determination b. Detection of central nervous system infection c. Estimation of intracranial pressure d. Identification of subarachnoid hemorrhage
ANS: B Magnetic resonance imaging (MRI) produces images with greater detail than computed tomography (CT) and provides views of several planes (sagittal, coronal, axial, and oblique) that are not possible with CT. MRI with contrast is the preferred study for detection of infectious and inflammatory processes of the central nervous system (CNS). MRI can detect areas of cerebral infarct within a few hours of the incident and can identify small areas of plaque in patients with multiple sclerosis. MRI with contrast is the preferred study for detection of infectious and inflammatory processes of the CNS, malignancy, and metastatic lesions; cervical spine imaging; and postoperative evaluation of tumor recurrence. MRI also is the diagnostic study of choice in the evaluation of spinal cord injury.
A patient with a serious head injury has been admitted. The nurse knows that certain neurologic findings can indicate the prognosis for the patient. Which finding denotes the most serious prognosis? a. Decorticate posturing b. Decerebrate posturing c. Absence of Babinski reflex d. Glasgow Coma Scale (GCS) score of 14
ANS: B Outcome studies indicate that abnormal flexion or decorticate posturing has a less serious prognosis than does extension, or decerebrate posturing. Onset of posturing or a change from abnormal flexion to abnormal extension requires immediate physician notification. The Babinski reflex is a pathologic finding; absence of this reflex is a normal neurologic finding in adults. The range of scores for the Glasgow Coma Scale is 3 to 15. A score of 14 denotes a minimal deficit.
The nurse is caring for a patient immediately after a craniotomy. When assessing the size and shape of the patient's pupils the nurse notes the patient's left pupil is oval. What does this finding indicate? a. Cortical dysfunction b. Intracranial hypertension c. Hydrocephalus d. Metabolic coma
ANS: B Pupil shape is also noted in the assessment of pupils. Although the pupil is normally round, an irregularly shaped or oval pupil may be noted in patients with eye surgery. Initial stages of cranial nerve III compression from elevated intracranial pressure can also cause the pupil to have an oval shape.
The nurses are admitting a neurologically impaired patient. The patient's family is present. How comprehensive should the initial history be? a. It should be limited to the chief complaint and personal habits. b. It should be all-inclusive, including events preceding hospitalization. c. It should be confined to current medications and family history. d. It should be restricted to only information that the patient can provide.
ANS: B The one factor common to all neurologic assessment is the need to obtain a comprehensive history of events preceding hospitalization.
The nurse is caring for a patient who has sustained a traumatic head injury. The practitioner has asked the nurse to test the patient's oculocephalic reflex. Which findings indicate that the patient has an intact oculocephalic reflex? a. The patient's eyes move in the same direction the head is turned. b. The patient's eyes move in the opposite direction to the movement of the patient's head. c. The patient's eyes rove and move in opposite directions from each other. d. The patient's eyes move up and down and then back and forth.
ANS: B To assess the oculocephalic reflex, the nurse holds the patient's eyelids open and briskly turns the head to one side while observing the eye movements and then briskly turns the head to the other side and observes. If the eyes deviate to the opposite direction in which the head is turned, doll's eyes are present, and the oculocephalic reflex arc is intact. If the oculocephalic reflex arc is not intact, the reflex is absent.
The practitioner has ordered a carotid Doppler study for a patient. The patient asks the nurse what the test is for. How should the nurse respond? a. The test evaluates blood flow in the anterior, middle, or posterior cerebral arteries. b. The test estimates blood flow velocity thought the carotid arteries. c. The test assesses arteriovenous circulation in the intracranial space. d. The test gauges global cerebral blood flow.
ANS: B Ultrasound technology, although not an absolute measure of cerebral blood flow, uses a noninvasive technique to provide information about the flow velocity of blood through carotid vessels. Carotid duplex studies are used as a routine screening procedure for intraluminal narrowing of the common and internal carotid arteries as a result of atherosclerotic plaques.
The patient's intracranial pressure (ICP) reading has gradually climbed from 15 to 23 mm Hg. The nurse's primary action is to: a. drain off 7 mm of cerebrospinal fluid (CSF) from the catheter. b. notify the physician. c. place the patient in a high Fowler position to decrease the pressure. d. check level of consciousness.
ANS: B Under normal physiologic conditions, mean intracranial pressure (ICP) is maintained below 15 mm Hg. An increase in ICP can decrease blood flow to the brain, causing brain damage. Persistent ICP elevation above 20 mm Hg remains the most significant factor associated with a fatal outcome.
Why is assessment of level of conscious (LOC) the most important aspect of the neurologic examination? a. The LOC is the most prognostic indicator of the patient's outcome. b. The LOC is generally limited to the Glasgow Coma Scale making it the quickest part of the assessment. c. In most situations the LOC deteriorates before any other neurologic changes are noted. d. The LOC is the easiest part of the neurologic exam and thus is generally performed first.
ANS: C Assessment of the level of consciousness is the most important aspect of the neurologic examination.
The nurse is caring for a patient who is going to have digital subtraction angiography. The patient asks what is the difference between conventional and digital subtraction angiography. What should the nurse tell the patient? a. Digital subtraction angiography has fewer complications. b. Digital subtraction angiography is noninvasive. c. Digital subtraction angiography uses significantly less dye. d. Digital subtraction angiography is done through the femoral vein.
ANS: C Digital subtraction angiography uses significantly less dye than arterial angiography. Dye is injected in the venous or arterial system. The patient must remain motionless during the procedure. Complications are the same as those for cerebral angiography.
The nurse is precepting a new graduate nurse. The new graduate asks about the difference between electroencephalography and evoked potentials. What should the nurse tell the new graduate? a. Evoked potentials measure and record electric and muscle activity in response to noxious stimuli. b. Electroencephalography measures cerebral blood flow and oxygen extraction. c. Evoked potentials measure cerebral electrical impulses generated in response to sensory stimuli. d. Electroencephalography measures the biochemical changes in the brain to assess metabolic activity.
ANS: C Evoked potentials involve the recording of electrical impulses generated by a sensory stimulus as it travels through the brainstem and into the cerebral cortex. Electroencephalography (EEG) records electric impulses, commonly called brain waves, generated by the brain.
The practitioner wishes to evaluate the functional integrity of cerebral motor pathways in a brain-injured patient. Which test should the nurse anticipate the practitioner will order? a. Electroencephalography b. Xenon computed tomography (CT) c. Motor-evoked potentials d. Emission tomography
ANS: C Motor-evoked potentials assess the functional integrity of descending motor pathways. The motor cortex is stimulated via direct high-voltage electric stimulation through the scalp or use of a magnetic field to induce an electrical current within the brain.
The nursing management plan for a patient undergoing a water-based contrast myelogram should include intervention? a. Maintain the patient flat in bed for 4 to 6 hours b. Observe the puncture sight every 15 minutes for 2 hours for signs of bleeding c. Keep the patient's head elevated 30 to 45 degrees for 8 hours d. Administer a sedative to keep the patient from moving around
ANS: C Postprocedure care includes keeping the patient's head elevated 30 to 45 degrees for 8 hours, monitoring neurologic status, and encouraging oral fluids.
The nurse is caring for a patient with a closed head injury with a Glasgow Coma Scale (GCS) score of 6. What does this score indicate about the patient's neurologic status? a. Patient is in a vegetative state. b. Patient is a paraplegic. c. Patient is in a coma. d. Patient is able to obey commands.
ANS: C The best possible score on the Glasgow Coma Scale (GCS) is 15, and the lowest score is 3. Generally, a score of 7 or less on the GCS indicates coma. Originally, the scoring system was developed to assist in general communication concerning the severity of neurologic injury.
A patient has been admitted with acute confusion and other focal neurologic signs. The practitioner is going to perform a lumbar puncture. What is an abnormal finding in the cerebrospinal fluid? a. Clear and colorless b. Glucose of 60 mg/dL c. Protein of 20 mg/dL d. 30 red blood cells
ANS: D Cerebrospinal fluid is normally a clear, colorless, odorless solution that contains 50 to 75 mg/dL of glucose, 5 to 25 mg/dL of protein, and no red blood cells.
The nurse is caring for a patient with a head injury and observes a rhythmic increase and decrease in the rate and depth of respiration followed by brief periods of apnea. What should the nurse document under breathing pattern? a. Central neurogenic hyperventilation b. Apneustic breathing c. Ataxic respirations d. Cheyne-Stokes respirations
ANS: D Cheyne-Stokes respirations have a rhythmic crescendo and decrescendo of rate and depth of respiration, including brief periods of apnea. These respirations are usually seen with bilateral deep cerebral lesions or some cerebellar lesions. Central neurogenic hyperventilations are very deep, very rapid respirations with no apneic periods. They are usually seen with lesions of the midbrain and upper pons. Apneustic breathing includes clusters of irregular, gasping respirations separated by long periods of apnea. They are usually seen in lesions of the lower pons or upper medulla. Ataxic respirations are irregular, random patterns of deep and shallow respirations with irregular apneic periods. They are usually seen in lesions of the medulla.
Cerebral infarction is a serious complication of which procedure? a. Extracranial Doppler b. Evoked potential testing c. Myelography d. Cerebral angiography
ANS: D Complications associated with cerebral angiography include cerebral embolus caused by the catheter dislodging a segment of atherosclerotic plaque in the vessel, hemorrhage or hematoma formation at the insertion site, vasospasm caused by the irritation of catheter placement, thrombosis of the extremity distal to the injection site, and allergic or adverse reaction to the contrast medium.
The nurse is starting a peripheral intravenous catheter in the right hand of an unconscious patient. During the procedure the patient reaches over with his left hand and tries to remove the noxious stimuli. How would the nurse document this response? a. Decorticate posturing b. Decerebrate posturing c. Withdrawal d. Localization
ANS: D Localization occurs when the extremity opposite to the extremity receiving pain crosses the midline of the body in an attempt to remove the noxious stimulus from the affected limb.
A patient is being prepared for a neurologic work-up. The practitioner is getting ready to perform a lumbar puncture. What is the best position for the nurse to place the patient in for the procedure? a. Prone b. Reverse Trendelenburg c. High Fowler d. Lateral recumbent position with knees and head slightly tucked.
ANS: D Patients undergoing a lumbar puncture are placed either in the lateral recumbent position, with the knees and head tightly tucked, or in the sitting position, leaning over a bedside table or some other support.
While the Glasgow Coma Scale (GCS) is part of the routine neurologic assessment, the nurse knows that it is not a valid measure for certain types of patients. In which patient is the GCS not valid? a. Patient with hemiplegia b. Patient with Parkinson disease c. Patient with dyslexia d. Patient who is intoxicated
ANS: D Several points should be kept in mind when the Glasgow Coma Scale is used for serial assessment. It provides data about level of consciousness only, and it should never be considered a complete neurologic examination. Additionally, it is not a sensitive tool for evaluation of an altered sensorium, and it does not account for possible aphasia or mechanical intubation. It is also a poor indicator of lateralization of neurologic deterioration
The nurse is precepting a new graduate nurse. The new graduate asks about testing the oculovestibular reflex. What should the nurse tell the new graduate? a. The test should not be performed on an unconscious patient because of the risk of aspiration. b. An abnormal response is manifested by conjugate, slow, tonic nystagmus, deviating toward the irrigated ear. c. This test should be included in the nursing neurologic examination of a patient with a head injury. d. This test is one of the final clinical assessments of brainstem function.
ANS: D The oculovestibular reflex is one of the final clinical assessments of brainstem function and is only performed by a practitioner. After confirmation that the tympanic membrane is intact, the head is raised to a 30-degree angle. Then 20 to 100 mL of ice water is injected into the external auditory canal. In a normal response, eye movement is in the direction of the injection site. An abnormal response is disconjugate eye movement, which indicates a brainstem lesion, or no response, which indicates little to no brainstem function.
Which nuclear medicine study should the nurse anticipate a practitioner's order for in a patient who is being evaluated for a brain tumor? a. PET b. MRI c. MRA d. SPECT
ANS: D The single-photon emission computed tomography (SPECT) test differs from positron emission tomography (PET) in that tracer stays in the bloodstream rather than being absorbed by surrounding tissue, thereby limiting the images to areas where blood flows. SPECT is cheaper and more readily available than higher resolution PET. The major clinical uses of SPECT are to detect cerebrovascular disease, seizures, and tumors. Magnetic resonance imaging and magnetic resonance angiography are radiographic imaging examinations.