Neuroimaging in Clinical Assessment — MCQs
Which radiopharmaceutical is commonly used in positron emission tomography (PET) imaging?
Which of the following investigations work on the same principle?
Which imaging modality is most sensitive for detecting early ischemic stroke?
Investigation of choice for leptomeningeal carcinomatosis:
Which of the following behavioral problems would suggest an organic brain lesion?
What is the maximum limit of observation period for diagnosis of insanity?
Deep vein thrombosis post-operatively is diagnosed by:
The clinical signs of brain-stem death include all of the following except:
An adolescent school girl complains of dropping objects from hands, it gets precipitated during morning and during exams. There is no history of loss of consciousness and her cousin sister has been diagnosed with epilepsy. EEG was suggestive of epileptic spikes. What is the diagnosis?
A businessman is brought for psychiatric evaluation due to recent denial of memory of taking multiple bank loans, despite all other memory functions being intact. This is suggestive of which of the following?
Neuroimaging in Clinical Assessment Indian Medical PG Practice Questions and MCQs
Question 1: Which radiopharmaceutical is commonly used in positron emission tomography (PET) imaging?
- A. 18F-FDG (Fluorodeoxyglucose) (Correct Answer)
- B. Oxygen-15 (used in specific PET scans)
- C. Carbon-11 acetate
- D. Nitrogen-13 ammonia
Explanation: ***18F-FDG (Fluorodeoxyglucose)*** - **18F-FDG** is the most widely used radiopharmaceutical in PET imaging, particularly for **oncology**, as it's a glucose analog that accumulates in metabolically active cells. - Its widespread use is due to its favorable physical properties for PET and its ability to reflect **tumor metabolism**. *Carbon-11 acetate* - **Carbon-11 acetate** is used in specific PET applications, primarily for **cardiac imaging** to assess myocardial oxidative metabolism. - It has a very short half-life (around 20 minutes) which limits its availability to centers with on-site cyclotrons. *Oxygen-15 (used in specific PET scans)* - **Oxygen-15** (e.g., O-15 water) is used in highly specialized PET scans for measuring **blood flow** and oxygen metabolism, especially in brain studies. - Its extremely short half-life (approximately 2 minutes) necessitates an on-site cyclotron and immediate use. *Nitrogen-13 ammonia* - **Nitrogen-13 ammonia** is a common radiopharmaceutical for **myocardial perfusion imaging** with PET, reflecting regional blood flow to the heart. - Like other C-11 and O-15 tracers, its short half-life (about 10 minutes) requires proximity to a cyclotron facility.
Question 2: Which of the following investigations work on the same principle?
- A. MRI and PET Scan
- B. CT and MRI
- C. CT and X-ray (Correct Answer)
- D. USG and HIDA Scan
Explanation: ***CT and X-ray*** - Both **Computed Tomography (CT)** and **X-ray** imaging utilize **ionizing radiation** to generate images of the body's internal structures. - They work by passing X-ray beams through the patient, with different tissues absorbing the radiation to varying degrees, which is then detected to create an image. *MRI and PET Scan* - **Magnetic Resonance Imaging (MRI)** uses **strong magnetic fields and radio waves** to create detailed images of soft tissues, based on water content. - **Positron Emission Tomography (PET) scans** use **radioactive tracers** to visualize metabolic activity and blood flow, detecting gamma rays emitted from the patient. *CT and MRI* - **CT scans** use **ionizing radiation** (X-rays) to produce cross-sectional images. - **MRI scans** use **magnetic fields and radio waves** and do not involve ionizing radiation. *USG and HIDA Scan* - **Ultrasound (USG)** uses **high-frequency sound waves** to create real-time images of organs and structures. - **Hepatobiliary Iminodiacetic Acid (HIDA) scans** are a type of nuclear medicine study that uses a **radioactive tracer** to evaluate liver and gallbladder function.
Question 3: Which imaging modality is most sensitive for detecting early ischemic stroke?
- A. Ultrasound
- B. PET scan
- C. CT
- D. MRI with DWI (Correct Answer)
Explanation: ***MRI with DWI*** - **Diffusion-weighted imaging (DWI)** within an MRI scan is highly sensitive in detecting **cytotoxic edema** within minutes of **ischemic stroke** onset. This makes it crucial for early diagnosis and treatment decisions. - DWI can identify areas of restricted water diffusion, which is a hallmark of acute cellular injury due to **ischemia**, even before changes are visible on conventional T1 or T2-weighted MRI sequences. *CT* - While frequently used in acute stroke settings, **non-contrast CT** is primarily used to **rule out hemorrhagic stroke** and may only show subtle or no signs of acute ischemia in the first few hours. - Early ischemic changes on CT, often referred to as the **"ischemic penumbra"**, may appear hours after stroke onset, making it less sensitive for very early detection compared to DWI. *Ultrasound* - **Transcranial Doppler (TCD) ultrasound** can evaluate blood flow velocities in intracranial arteries and detect stenoses or occlusions but is not a primary imaging modality for directly visualizing brain parenchymal ischemia. - Cervical ultrasound (e.g., **carotid duplex**) assesses extracranial vessels but cannot directly detect **ischemic changes** within the brain tissue itself. *PET scan* - **PET (Positron Emission Tomography)** can assess brain metabolism and blood flow but is typically not the preferred or most sensitive modality for **early detection of acute ischemic stroke** due to its complexity, cost, and limited availability in emergency settings. - PET is more commonly used in research or for assessing chronic conditions and **metabolic abnormalities**, rather than acute stroke diagnosis.
Question 4: 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 5: Which of the following behavioral problems would suggest an organic brain lesion?
- A. Auditory hallucinations
- B. Formal thought disorder
- C. Depression
- D. Visual hallucinations (Correct Answer)
Explanation: ***Visual hallucinations*** - While visual hallucinations can occur in primary psychiatric disorders, they are *more commonly* associated with **organic brain lesions** (e.g., tumors, delirium, dementia, substance withdrawal) compared to auditory hallucinations. - They often indicate **neurological dysfunction** and warrant further investigation for an underlying physical cause. *Auditory hallucinations* - **Auditory hallucinations** are a hallmark symptom of **psychotic disorders** such as **schizophrenia**, and are less specific for organic brain lesions unless they are complex and multimodal. - While possible in organic conditions (e.g., temporal lobe epilepsy), they are more strongly linked to functional psychiatric illness than visual hallucinations. *Formal thought disorder* - **Formal thought disorder** (e.g., loosening of associations, word salad, tangentiality) is a core symptom of **schizophrenia** and other primary psychotic disorders. - It is a disturbance in the *form* of thought rather than its content, and is primarily a **psychiatric phenomenon**. *Depression* - **Depression** is a common mood disorder with diverse etiologies, including psychosocial stressors and neurochemical imbalances, but it is not typically indicative of a focal **organic brain lesion**. - Although depression can coexist with neurological conditions, it is not a direct behavioral symptom of a localized brain injury.
Question 6: What is the maximum limit of observation period for diagnosis of insanity?
- A. 50 days
- B. 30 days (Correct Answer)
- C. 5 days
- D. 10 days
Explanation: ***30 days*** - The maximum observation period for diagnosing **insanity** in a legal context is typically set at **30 days**. - This period allows for sufficient time to conduct thorough psychiatric evaluations, observe behavior, and gather collateral information to establish the presence or absence of a **mental disorder** at the time of the alleged offense. *50 days* - An observation period of **50 days** is excessively long for routine determination of insanity in most legal jurisdictions. - While prolonged observation might occur in complex or unusual cases, it is not the standard maximum limit. *5 days* - A **5-day observation period** is generally too short to reliably diagnose or rule out **insanity**. - Many mental health conditions may not manifest consistently within such a brief timeframe, leading to potentially inaccurate assessments. *10 days* - **10 days** is also considered an insufficient period for a comprehensive evaluation of **insanity**. - It may not provide enough opportunity to observe fluctuations in mental state or to gather all necessary diagnostic information.
Question 7: Deep vein thrombosis post-operatively is diagnosed by:
- A. Clinically
- B. Ascending venography
- C. USG (Correct Answer)
- D. X-ray
Explanation: ***USG*** - **Duplex ultrasonography** is the preferred and most common imaging modality for diagnosing deep vein thrombosis (DVT) due to its non-invasive nature, accessibility, and high accuracy. - It visualizes the **vein lumen** and assesses **compressibility**, a key diagnostic feature for DVT. *Clinically* - Clinical diagnosis of DVT is unreliable, as symptoms like **leg swelling, pain, and tenderness** are non-specific and can be caused by other conditions. - While clinical suspicion can warrant further investigation, it is **insufficient for definitive diagnosis**. *Ascending venography* - **Ascending venography** was once considered the gold standard but is now rarely used due to its invasive nature, use of ionizing radiation, and potential complications. - It involves injecting **radiocontrast dye** into a foot vein and taking X-rays, making it less practical for routine use compared to ultrasound. *X-ray* - **X-rays do not directly visualize veins** or blood clots and are therefore not useful for diagnosing DVT. - They may be used to rule out other causes of leg pain or swelling, such as **bone fractures** or **arthritis**, but offer no diagnostic value for DVT itself.
Question 8: The clinical signs of brain-stem death include all of the following except:
- A. Absence of spontaneous respiration
- B. Profound hypotension (Correct Answer)
- C. Absent oculo-vestibular reflex
- D. Absence of pharyngeal reflex
Explanation: **Profound hypotension** - While patients with brainstem death can be hemodynamically unstable, **profound hypotension** itself is not a defining diagnostic criterion for brainstem death. It is often a consequence of brainstem injury, but not a direct sign indicating loss of brainstem function. - The criteria for brainstem death focus on the irreversible cessation of all brainstem reflexes and the capacity for spontaneous respiration, not peripheral circulatory status. *Absence of spontaneous respiration* - The **apnea test**, demonstrating no respiratory efforts despite adequate CO2 stimulation, is a critical component of brainstem death diagnosis, indicating irreversible loss of brainstem respiratory centers. - This sign confirms the total and irreversible cessation of the brainstem's ability to maintain vital functions. *Absent oculo-vestibular reflex* - The absence of the **oculo-vestibular reflex** (cold caloric test) indicates irreversible damage to the brainstem nuclei responsible for eye movements and vestibular function. - This is a key diagnostic criterion demonstrating the loss of specific brainstem reflexes. *Absence of pharyngeal reflex* - The absence of the **pharyngeal reflex** (gag reflex) signifies the loss of cranial nerve IX and X function, which are mediated by the brainstem. - This confirms the irreversible cessation of a vital protective reflex regulated by the brainstem.
Question 9: An adolescent school girl complains of dropping objects from hands, it gets precipitated during morning and during exams. There is no history of loss of consciousness and her cousin sister has been diagnosed with epilepsy. EEG was suggestive of epileptic spikes. What is the diagnosis?
- A. Juvenile myoclonic epilepsy (Correct Answer)
- B. Benign rolandic epilepsy
- C. Atypical absence
- D. Choreo-athetoid epilepsy
Explanation: ***Juvenile myoclonic epilepsy*** - This diagnosis is supported by the patient's age (adolescent), the **myoclonic jerks** (dropping objects), precipitation in the morning or with stress (exams), and a family history of epilepsy. - The **EEG showing epileptic spikes** further confirms the diagnosis, as **polyspike-wave discharges** are characteristic. *Benign rolandic epilepsy* - Typically presents with **nocturnal seizures** involving facial and pharyngeal muscles, often with speech arrest and salivation. - While it occurs in childhood, it is usually outgrown by adolescence and does not typically manifest as dropping objects or with morning precipitation. *Atypical absence* - Characterized by **brief staring spells with altered consciousness**, but usually with more pronounced motor phenomena than typical absence seizures. - However, the prominent myoclonic jerks and the familial history described here are more consistent with JME. *Choreo-athetoid epilepsy* - This is not a recognized epilepsy syndrome; choreoathetosis refers to a type of **movement disorder** characterized by involuntary, jerky, writhing movements. - While movement disorders can be associated with some forms of epilepsy, the primary presentation described does not fit this classification.
Question 10: A businessman is brought for psychiatric evaluation due to recent denial of memory of taking multiple bank loans, despite all other memory functions being intact. This is suggestive of which of the following?
- A. Dissociative amnesia (Correct Answer)
- B. Dissociative fugue
- C. Dissociative identity disorder
- D. Dissociative autonomic dysfunction
Explanation: **Explanation:** The clinical presentation describes a patient with selective memory loss related to a specific stressful or traumatic event (taking multiple bank loans) while maintaining an otherwise intact memory. This is the hallmark of **Dissociative Amnesia**. **1. Why Dissociative Amnesia is correct:** Dissociative amnesia is characterized by an inability to recall important personal information, usually of a stressful or traumatic nature, that is too extensive to be explained by ordinary forgetfulness. In this case, the businessman’s "denial" is not a conscious lie (malingering) but a psychological defense mechanism where the memory is sequestered from conscious awareness. Crucially, there is no underlying organic brain pathology, and general cognitive functions remain preserved. **2. Why other options are incorrect:** * **Dissociative Fugue:** This involves sudden, unexpected travel away from home combined with an inability to recall one’s past and, occasionally, the assumption of a new identity. The patient here has not traveled or lost his identity. * **Dissociative Identity Disorder (DID):** This requires the presence of two or more distinct personality states that take control of behavior, accompanied by gaps in memory. There is no evidence of multiple personalities here. * **Dissociative Autonomic Dysfunction:** This refers to physical symptoms (like palpitations or tremors) mediated by the autonomic nervous system that have a psychological origin. It does not involve memory loss. **Clinical Pearls for NEET-PG:** * **Localized Amnesia:** The most common type; failure to recall events during a specific period. * **Selective Amnesia:** Can remember some, but not all, events during a specific period (as seen in this businessman). * **Primary Gain:** Keeping the internal conflict out of awareness. * **Secondary Gain:** Tangible external benefits (e.g., avoiding loan repayment), though the amnesia itself is an unconscious process. * **Treatment:** The first-line approach is usually psychotherapy; "Amobarbital interviews" (Narcoanalysis) can sometimes be used to recover memories.
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