Functional Imaging in Neurology — MCQs
Best imaging modality for acoustic neuroma screening
A lady presented with a 4 cm tumor in the left parietal lobe for which she underwent surgery and radiotherapy. After 3 months she presented with headache and vomiting. Which of the following would characterize the lesion in the patient?
Investigation of choice for leptomeningeal carcinomatosis:
The investigation of choice for vestibular schwannoma is
Investigation of choice for acute intracerebral hemorrhage is -
What is the earliest symptom to show improvement with thiamine therapy in Wernicke's encephalopathy?
A 2-year-old boy has been doing well despite his diagnosis of tetralogy of Fallot. He presented to an outside ER a few days ago with a complaint of an acute febrile illness for which he was started on a "pink, bubble-gum tasting antibiotic." His mother reports that for the past 12 hours or so he has been holding his head saying it hurts and he is less active than normal. On your examination, he seems to have a severe headache, nystagmus, and ataxia. Which of the following would be the most appropriate first test to order?
A patient developed memory deficit for recent events. Anterograde amnesia is a feature of:
A patient presents with a suspected cervical spine injury following an accident. What is the first step in management?
Subacute Sclerosing Panencephalitis is a rare and dangerous complication of;
Functional Imaging in Neurology Indian Medical PG Practice Questions and MCQs
Question 1: Best imaging modality for acoustic neuroma screening
- A. Nuclear scan
- B. CT temporal bone
- C. MRI with gadolinium (Correct Answer)
- D. Plain skull X-ray
Explanation: ***MRI with gadolinium*** - **Magnetic Resonance Imaging (MRI) with gadolinium contrast** is the gold standard for acoustic neuroma (vestibular schwannoma) detection due to its superior soft tissue resolution. - It effectively visualizes **small tumors** arising from the vestibular nerve within the internal auditory canal and cerebellopontine angle. *Nuclear scan* - **Nuclear scans** are generally used for assessing metabolic activity or specific tissue uptake, such as in oncology for metastasis detection or thyroid conditions. - They lack the **anatomical detail and resolution** needed to visualize small intracranial tumors like acoustic neuromas. *CT temporal bone* - **CT scans of the temporal bone** are excellent for evaluating bony structures, such as fractures or erosion of the internal auditory canal. - However, they have **limited sensitivity for soft tissue masses** and can miss small acoustic neuromas. *Plain skull X-ray* - **Plain skull X-rays** provide very limited information about soft tissues and are not useful for screening or diagnosing acoustic neuromas. - They mainly visualize **gross bony abnormalities** and cannot detect subtle pathologies within the internal auditory canal or cerebellopontine angle.
Question 2: A lady presented with a 4 cm tumor in the left parietal lobe for which she underwent surgery and radiotherapy. After 3 months she presented with headache and vomiting. Which of the following would characterize the lesion in the patient?
- A. Digital subtraction angiography with dual source CT scan
- B. Gd-enhanced MRI
- C. 99Tc-HMPAO SPECT brain
- D. 18FDG PET Scan (Correct Answer)
Explanation: ***18FDG PET Scan*** - This patient, presenting with new neurological symptoms after **surgery and radiotherapy** for a cerebral tumor, faces a diagnostic dilemma: differentiating between **tumor recurrence** and **radiation necrosis**. - **18FDG PET scans** effectively distinguish between these two conditions because viable tumor cells exhibit high metabolic activity and thus actively take up **fluorodeoxyglucose (FDG)**, while radiation necrosis is metabolically inactive and shows little to no FDG uptake. *Digital subtraction angiography with dual source CT scan* - **Digital subtraction angiography (DSA)** is primarily used to visualize **vascular structures** and is not the modality of choice for differentiating tumor recurrence from radiation necrosis. - A **dual-source CT scan** is useful for rapid imaging and dynamic studies but lacks the metabolic information needed for this specific differentiation. *Gd-enhanced MRI* - While **Gd-enhanced MRI** is excellent for detecting **structural changes** and **blood-brain barrier disruption**, it often cannot definitively differentiate between **tumor recurrence** and **radiation necrosis**. - Both conditions can present with similar **enhancement patterns** on MRI, making differentiation challenging without additional metabolic information. *99Tc-HMPAO SPECT brain* - **99mTc-HMPAO SPECT** measures **regional cerebral blood flow (rCBF)**, which can be altered in both tumors and areas of radiation injury. - However, it does not provide the specific metabolic information (glucose metabolism) needed to reliably distinguish between **viable tumor cells** and **radiation necrosis** as effectively as FDG PET.
Question 3: Investigation of choice for leptomeningeal carcinomatosis:
- A. Gd enhanced MRI (Correct Answer)
- B. CT scan
- C. SPECT
- D. PET
Explanation: ***Gd enhanced MRI*** - **Gadolinium-enhanced MRI** is the investigation of choice for **leptomeningeal carcinomatosis** as it can visualize the subtle nodular or linear enhancement along the leptomeninges, indicating tumor dissemination. - It offers superior **soft tissue contrast** and spatial resolution compared to CT, enabling detection of small lesions and accurate mapping of disease extent. *CT scan* - A **CT scan** has limited sensitivity for detecting leptomeningeal involvement due to poor contrast resolution of soft tissues and the dura/arachnoid spaces. - It might show hydrocephalus or large tumor deposits, but subtle leptomeningeal enhancement is often missed. *SPECT* - **Single photon emission computed tomography (SPECT)** is primarily used for functional imaging and is not the investigation of choice for anatomical visualization of leptomeningeal carcinomatosis. - Its resolution is too low to detect the fine structural changes associated with leptomeningeal spread. *PET* - **Positron emission tomography (PET)**, often combined with CT, identifies metabolically active tumor cells and can detect diffuse metastatic disease. - While useful for overall cancer staging and identifying primary lesions, it is less effective than gadolinium-enhanced MRI for directly visualizing the morphology and enhancement patterns of leptomeningeal carcinomatosis due to limited spatial resolution in the CSF spaces.
Question 4: The investigation of choice for vestibular schwannoma is
- A. Gadolinium enhanced MRI (Correct Answer)
- B. PET scan
- C. SPECT
- D. Contrast enhanced CT scan
Explanation: ***Gadolinium enhanced MRI*** - **Gadolinium-enhanced MRI** is the gold standard due to its superior spatial resolution for soft tissues, allowing for clear visualization of the tumor within the **internal auditory canal** and **cerebellopontine angle**. - It effectively detects even small **vestibular schwannomas**, which are typically missed by other imaging modalities. *PET scan* - **PET scans** are primarily used for assessing metabolic activity in tumors and are more relevant for distinguishing between benign and malignant lesions, or for staging cancer, rather than purely anatomical localization of a **vestibular schwannoma**. - Its resolution is often insufficient to precisely delineate small lesions in the **internal auditory canal**. *SPECT* - **SPECT** uses gamma-ray emitting radiotracers and is more commonly employed in nuclear medicine for functional imaging of organs or to assess blood flow, particularly in cardiac or neurological conditions like epilepsy, rather than for detailed anatomical imaging of tumors such as **vestibular schwannomas**. - Its spatial resolution is generally lower than MRI, making it less suitable for detecting small lesions in complex anatomical regions. *Contrast enhanced CT scan* - While a **contrast-enhanced CT scan** can show larger tumors and bony erosion, its soft tissue contrast is inferior to MRI, which means it may miss smaller **vestibular schwannomas**. - It also exposes the patient to **ionizing radiation**, and its primary role in vestibular schwannoma detection is often limited to cases where MRI is contraindicated.
Question 5: Investigation of choice for acute intracerebral hemorrhage is -
- A. NCCT (Correct Answer)
- B. MRI
- C. PET scan
- D. None of the options
Explanation: ***NCCT*** - **Non-contrast Computed Tomography (NCCT)** is the investigation of choice for acute intracerebral hemorrhage because it can **rapidly and reliably detect acute blood** within the brain parenchyma. - Acute hemorrhage appears as a **hyperdense (bright) lesion** on NCCT, allowing for quick diagnosis and management vital in emergency settings. *MRI* - While MRI can detect hemorrhage, its sensitivity for **acute hemorrhage** can be variable, and it is **less readily available** and takes longer to perform than NCCT. - MRI is generally preferred for subacute or chronic hemorrhage, or to investigate the **underlying cause** of the bleed (e.g., tumor, vascular malformation). *PET scan* - **Positron Emission Tomography (PET) scan** primarily measures **metabolic activity** and blood flow within the brain. - It is **not suitable for detecting acute bleeding** and is typically used for diagnosing conditions like tumors, epilepsy, or neurodegenerative diseases. *None of the options* - This option is incorrect because **NCCT** is indeed the gold standard for diagnosing acute intracerebral hemorrhage.
Question 6: What is the earliest symptom to show improvement with thiamine therapy in Wernicke's encephalopathy?
- A. Ataxia
- B. Ophthalmoplegia (Correct Answer)
- C. Confusion
- D. Not all symptoms respond equally
Explanation: ***Ophthalmoplegia*** - **Ophthalmoplegia** is often the first and most dramatic symptom to improve with thiamine administration, sometimes within hours [1]. - This rapid response is due to the restoration of thiamine-dependent enzyme function in the brainstem nuclei controlling eye movements. *Ataxia* - While **ataxia** does improve with thiamine therapy, its resolution is typically slower and less complete than ophthalmoplegia [1]. - Residual gait disturbance can persist in some patients despite treatment. *Confusion* - **Confusion** and global cognitive impairment improve gradually with thiamine, but not as quickly as eye movement abnormalities [1]. - Severe cognitive deficits and amnesia associated with Wernicke-Korsakoff syndrome may not fully resolve [1]. *Not all symptoms respond equally* - This statement is true, but it doesn't identify which specific symptom improves earliest. - The differential response highlights the varying degrees of reversibility of neurological damage in Wernicke's encephalopathy.
Question 7: A 2-year-old boy has been doing well despite his diagnosis of tetralogy of Fallot. He presented to an outside ER a few days ago with a complaint of an acute febrile illness for which he was started on a "pink, bubble-gum tasting antibiotic." His mother reports that for the past 12 hours or so he has been holding his head saying it hurts and he is less active than normal. On your examination, he seems to have a severe headache, nystagmus, and ataxia. Which of the following would be the most appropriate first test to order?
- A. CT or MRI of the brain (Correct Answer)
- B. Lumbar puncture
- C. Urine drug screen
- D. Blood culture
Explanation: ***CT or MRI of the brain*** - The patient's history of **tetralogy of Fallot** puts him at increased risk for a **brain abscess** due to right-to-left shunting, bypassing pulmonary filtration of bacteria. - New onset of severe headache, nystagmus, and ataxia in this context strongly suggests an **intracranial mass lesion**, making immediate imaging crucial. *Lumbar puncture* - Performing a **lumbar puncture** in the presence of signs of elevated intracranial pressure (severe headache, nystagmus, ataxia) or suspicion of a mass lesion (brain abscess) is **contraindicated** due to the risk of herniation. - While it can diagnose meningitis, the clinical picture with focal neurological signs makes a mass lesion a higher concern that needs to be ruled out first. *Urine drug screen* - The patient's symptoms (severe headache, nystagmus, ataxia) are not typical for drug intoxication in a 2-year-old, especially given the history of a recent febrile illness and a congenital heart defect. - There is no clinical indication for drug use in this young child, and this test would not address the serious neurological symptoms. *Blood culture* - While a blood culture might be useful to identify a systemic infection, it will not directly explain or diagnose the acute focal neurological deficits such as nystagmus and ataxia, and the severe headache. - Given the high suspicion of an intracranial lesion with risk of herniation, obtaining imaging is a higher priority than waiting for blood culture results, which would take time.
Question 8: A patient developed memory deficit for recent events. Anterograde amnesia is a feature of:
- A. Traumatic paraplegia
- B. Stroke
- C. Spinal cord injury
- D. Post-head injury (Correct Answer)
Explanation: ***Post-head injury*** - **Anterograde amnesia**, the inability to form new memories after an event, is a common consequence of **traumatic brain injury** or **head injury** affecting memory-related brain structures [1], [3]. - Damage to areas like the **hippocampus** and medial temporal lobes, often seen in head trauma, directly impairs memory consolidation [2]. *Traumatic paraplegia* - **Paraplegia** refers to paralysis affecting the lower half of the body, usually due to a **spinal cord injury**. - This condition primarily impacts motor and sensory functions below the level of injury and does not directly cause memory deficits. *Stroke* - A **stroke** can cause various neurological deficits depending on the affected brain region, including memory impairment if crucial memory centers are involved. - However, the question specifically mentions **anterograde amnesia** following an unspecified "event," and while possible, post-head injury is a more classic and common association for this specific symptom profile [1]. *Spinal cord injury* - A **spinal cord injury** primarily affects the transmission of motor, sensory, and autonomic signals between the brain and the body. - It does not directly impact cognitive functions like memory formation, as the **spinal cord** is distinct from the brain structures responsible for memory.
Question 9: A patient presents with a suspected cervical spine injury following an accident. What is the first step in management?
- A. perform imaging studies
- B. administer oxygen
- C. stabilize the cervical spine (Correct Answer)
- D. log roll the patient
Explanation: ***stabilize the cervical spine*** - In any suspected cervical spine injury, the **first and most critical step is to stabilize the cervical spine** to prevent further neurological damage. This is achieved through manual inline stabilization, followed by a **rigid cervical collar** and placement on a backboard. - This immediate stabilization is paramount before any other assessments or interventions that could potentially worsen the injury. *perform imaging studies* - While imaging studies (e.g., X-ray, CT scan) are crucial for diagnosing the extent of cervical spine injury, they should only be performed **after the spine has been adequately stabilized**. - Performing imaging prior to stabilization risks **further displacement** of vertebrae and spinal cord injury. *administer oxygen* - Administering oxygen is an important step in **maintaining adequate oxygenation** and is part of initial resuscitation, but it does not take priority over cervical spine stabilization in a trauma setting. - **Airway, Breathing, Circulation (ABC)** management should always incorporate cervical spine protection. *log roll the patient* - **Log rolling** is a technique used to move a patient with a suspected spinal injury, but it must be performed **only after the cervical spine is stabilized** and with sufficient personnel to ensure coordinated movement. - Log rolling is not the first step in management; rather, it is a technique for patient assessment and transfer once initial stabilization is achieved.
Question 10: Subacute Sclerosing Panencephalitis is a rare and dangerous complication of;
- A. Rubella
- B. Varicella
- C. Mumps
- D. Measles (Correct Answer)
Explanation: ***Measles*** - **Subacute sclerosing panencephalitis (SSPE)** is a rare, fatal degenerative disease of the central nervous system caused by persistent infection with a defective **measles virus**. [1] - It typically develops **years after the initial measles infection**, affecting children and young adults, leading to cognitive decline, seizures, and motor dysfunction. [1], [2] *Rubella* - While rubella can cause congenital rubella syndrome, it is **not associated with SSPE**. - Complications of rubella usually involve birth defects, such as **cardiac malformations**, **deafness**, and **cataracts**, when acquired during pregnancy. *Varicella* - **Varicella-zoster virus (VZV)** causes chickenpox and shingles, but it is **not a known cause of SSPE**. - Neurological complications of VZV can include **cerebellar ataxia** or **encephalitis** acutely, or **postherpetic neuralgia** in later life. *Mumps* - Mumps virus can cause **parotitis**, **orchitis**, and **meningitis/encephalitis**, but it is **not implicated in the development of SSPE**. - The encephalitis associated with mumps typically occurs during the acute infection and generally has a good prognosis.
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