Functional Imaging in Oncology Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Functional Imaging in Oncology. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Functional Imaging in Oncology Indian Medical PG Question 1: Gold standard investigation for breast carcinoma screening in a patient with silicone breast implants
- A. Mammography
- B. CT scan
- C. USG
- D. MRI (Correct Answer)
Functional Imaging in Oncology Explanation: ***MRI***
- **MRI** is considered the **gold standard** for breast cancer screening in patients with silicone breast implants due to its superior ability to visualize breast tissue through the implant and detect subtle lesions.
- It offers **high sensitivity** in detecting both implant rupture and early malignancies, often providing better clarity than mammography in augmented breasts where implants can obscure tissue.
*Mammography*
- While a standard screening tool, **mammography** can be limited in patients with silicone implants because the implants can **obscure adjacent breast tissue**, making detection of small masses challenging.
- Special views (e.g., **Eklund views**) can be used, but sensitivity is still reduced compared to MRI in augmented breasts.
*CT scan*
- **CT scans** are not routinely used for primary breast cancer screening due to their use of **ionizing radiation** and lower sensitivity for detecting early breast lesions compared to MRI.
- CT is more commonly used for **staging** advanced cancers or evaluating complex masses detected by other modalities.
*USG*
- **Ultrasound (USG)** is a valuable complementary tool, especially for evaluating palpable lumps or clarifying findings from mammography, but it is **operator-dependent** and has a lower overall sensitivity for general screening compared to MRI.
- It is particularly useful for differentiating between **cystic and solid masses** and detecting implant ruptures but is not the gold standard for comprehensive screening in augmented breasts.
Functional Imaging in Oncology Indian Medical PG Question 2: On MRI, which of the following shows diffusion restriction?
- A. Ependymoma
- B. Meningioma
- C. Medulloblastoma (Correct Answer)
- D. Germinoma
Functional Imaging in Oncology Explanation: ***Medulloblastoma***
- **Medulloblastomas** are highly cellular tumors, leading to **restricted diffusion** on MRI due to the dense packing of cells and reduced extracellular space.
- This feature helps distinguish them from other posterior fossa tumors like ependymomas and pilocytic astrocytomas.
- They are the **most common malignant posterior fossa tumor in children** and show bright signal on DWI with low ADC values.
*Ependymoma*
- **Ependymomas** typically show **facilitated diffusion** or no significant diffusion restriction on MRI due to their less cellular nature and higher water content.
- They often arise from the ependyma lining the ventricles and can have heterogeneous signal characteristics.
- Variable ADC values are seen, generally higher than medulloblastomas.
*Meningioma*
- **Meningiomas** usually do not show significant **diffusion restriction**; instead, they have an appearance reflecting their fibrous and vascular nature.
- They tend to be extra-axial, dural-based tumors that enhance homogenously.
- ADC values are typically elevated compared to highly cellular tumors.
*Germinoma*
- **Germinomas** are also highly cellular tumors and **do show diffusion restriction** similar to medulloblastomas.
- However, they are typically located in the **pineal or suprasellar regions**, not the posterior fossa.
- In this context, **medulloblastoma** is the best answer as the classic example of a diffusion-restricting posterior fossa tumor commonly tested in examinations.
Functional Imaging in Oncology Indian Medical PG Question 3: Investigation of choice for leptomeningeal carcinomatosis:
- A. Gd enhanced MRI (Correct Answer)
- B. CT scan
- C. SPECT
- D. PET
Functional Imaging in Oncology 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.
Functional Imaging in Oncology Indian Medical PG Question 4: Radiation-induced necrosis can be diagnosed by:
- A. MRI
- B. CT
- C. PET
- D. Biopsy (Correct Answer)
Functional Imaging in Oncology Explanation: ***Biopsy***
- A **biopsy** is the definitive diagnostic method for radiation-induced necrosis, allowing for histological examination of tissue to confirm necrosis and rule out residual or recurrent tumor. [1], [2]
- It provides a direct view of cellular changes, identifying **necrosis, atypical cells**, and ruling out **malignancy**.
*MRI*
- While **MRI** can show structural changes indicative of necrosis (e.g., mass effect, edema), it often cannot definitively differentiate between **radiation necrosis** and **tumor recurrence.** [2]
- It often shows **T1 hypointensity** and **T2 hyperintensity**, but these findings are not specific.
*CT*
- **CT scans** are useful for detecting gross changes like **mass effect** and **edema** but have limited sensitivity for distinguishing necrosis from tumor recurrence.
- It may show **low-density lesions** but lacks the resolution and specificity for precise diagnosis.
*PET*
- **PET scans** measure metabolic activity and can help distinguish between **tumor recurrence** (high uptake) and **radiation necrosis** (low uptake) in some cases.
- However, false positives can occur, as some inflammatory processes in necrosis can also show increased uptake, making it **less definitive** than a biopsy.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1307-1308.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 340-341.
Functional Imaging in Oncology Indian Medical PG Question 5: Distant bone metastases can be best detected by which of the following imaging techniques?
- A. Bone scan (Correct Answer)
- B. CT
- C. Intravenous venogram
- D. PET scan
Functional Imaging in Oncology Explanation: ***Bone scan***
- A **bone scan** is highly sensitive for detecting **osteoblastic activity**, which is characteristic of most bone metastases.
- It involves injecting a **radioactive tracer** (usually technetium-99m methylene diphosphonate) that accumulates in areas of increased bone turnover, making it excellent for surveying the entire skeletal system.
*PET scan*
- While a **PET scan** (Positron Emission Tomography) can detect bone metastases, especially with **FDG-PET**, it is generally more expensive and may not be as sensitive for purely **osteoblastic lesions** as a bone scan.
- Its primary role is often in assessing metabolic activity of the primary tumor and other distant soft tissue metastases.
*CT*
- **CT scans** (Computed Tomography) are excellent for assessing bone anatomy, cortical destruction, and soft tissue involvement, but they are generally less sensitive for detecting early or widespread **osseous metastatic disease** compared to a bone scan.
- CT provides detailed anatomical information but may miss early **marrow involvement** that alters bone metabolism.
*Intravenous venogram*
- An **intravenous venogram** is an imaging technique used to visualize veins, primarily for detecting **thrombosis** or venous insufficiency.
- It has no role in the detection of **bone metastases**, as it provides no information about bone structure or metabolic activity.
Functional Imaging in Oncology Indian Medical PG Question 6: MUGA scan is not useful in:
- A. Stroke volume
- B. Regional wall perfusion (Correct Answer)
- C. Left ventricular ejection fraction
- D. Regional wall motion
Functional Imaging in Oncology Explanation: ***Regional wall perfusion***
- A MUGA scan assesses **ventricular function** through blood pool imaging, evaluating wall motion and ejection fraction.
- It does not directly visualize or quantify myocardial perfusion, which is the flow of blood through the coronary arteries to the heart muscle.
*Stroke volume*
- A MUGA scan accurately measures **end-diastolic volume** and **end-systolic volume**, from which stroke volume (EDV – ESV) can be calculated.
- This parameter directly reflects the amount of blood pumped out by the ventricle with each beat.
*Left ventricular ejection fraction*
- The MUGA scan is considered a gold standard for calculating **left ventricular ejection fraction** (LVEF), a key indicator of cardiac pump function.
- It uses a count-based method from gated blood pool images to determine the percentage of blood ejected from the left ventricle.
*Regional wall motion*
- MUGA scans are highly effective in assessing **regional wall motion abnormalities**, identifying areas of **hypokinesis**, **akinesis**, or **dyskinesis**.
- This is crucial for diagnosing and monitoring conditions like myocardial ischemia or infarction, and is a primary utility of the scan.
Functional Imaging in Oncology Indian Medical PG Question 7: In a child, non-functioning kidney is best diagnosed by:
- A. Ultrasonography
- B. IVU
- C. Creatinine clearance
- D. DTPA renogram (Correct Answer)
Functional Imaging in Oncology Explanation: ***DTPA renogram***
- A **DTPA (diethylenetriamine pentaacetic acid) renogram** is a nuclear medicine study that assesses **renal blood flow**, **glomerular filtration**, and urinary drainage. It directly measures the function of each kidney by quantifying tracer uptake and excretion, making it ideal for diagnosing a non-functioning kidney in a child.
- The test provides information on the **relative function** of each kidney and outflow obstruction, which is crucial for determining if a kidney is truly non-functioning rather than just poorly visualized.
*Ultrasonography*
- While ultrasound can visualize the **anatomy** of the kidney (size, shape, presence of hydronephrosis), it does not directly assess renal function.
- It may show a small, atrophic, or poorly developed kidney, but cannot definitively determine if it is non-functioning without functional studies.
*IVU (Intravenous Urogram)*
- An **IVU** relies on the kidneys' ability to excrete contrast material, which is visualized by X-ray. If a kidney is non-functioning, it will not excrete the contrast, leading to non-visualization.
- However, IVU exposes the child to **radiation** and **iodinated contrast**, and newer, safer, and more precise functional studies like renograms are preferred, especially in pediatric cases where radiation exposure should be minimized.
*Creatinine clearance*
- **Creatinine clearance** is a measure of overall **glomerular filtration rate (GFR)** for both kidneys combined.
- It does not provide information on the individual function of each kidney, so it cannot diagnose a non-functioning unilateral kidney.
Functional Imaging in Oncology Indian Medical PG Question 8: Tc-labeled RBCs are used for all except:
- A. Liver adenoma (Correct Answer)
- B. LV function
- C. GI bleeding
- D. Liver hemangioma
Functional Imaging in Oncology Explanation: ***Liver adenoma***
- Tc-labeled RBCs are primarily used to highlight a specific type of tissue or process. **Liver adenomas** do not typically show an affinity for **Tc-labeled RBCs**, as they are benign epithelial tumors with a different vascular composition.
- While adenomas can be vascular, they do not inherently contain the **vascular pooling** or blood volume characteristics that would be specifically targeted by **Tc-labeled RBCs** for diagnostic imaging.
*LV function*
- **Tc-labeled RBCs** (or Tc-99m-pertechnetate) are commonly used in **gated blood pool imaging** (MUGA scan) to assess **left ventricular (LV) function**, including **ejection fraction** and wall motion abnormalities.
- This technique directly visualizes the blood pool within the cardiac chambers, making it suitable for assessing functional parameters of the heart.
*GI bleeding*
- **Tc-labeled RBCs** are a standard imaging agent for detecting and localizing **active gastrointestinal (GI) bleeding**, especially when the bleeding rate is intermittent or slow.
- The labeled RBCs extravasate at the site of hemorrhage, creating a 'hot spot' that can be identified over time.
*Liver hemangioma*
- **Tc-labeled RBCs** are highly effective in diagnosing **liver hemangiomas**, which are benign vascular tumors composed of large, dilated blood vessels.
- These lesions show characteristic uptake and retention of **labeled RBCs** due to their slow blood flow and large intravascular space, appearing as early peripheral enhancement with subsequent centripetal filling.
Functional Imaging in Oncology Indian Medical PG Question 9: CD40 deficiency in a person signifies?
- A. IgG increase
- B. T cell absent
- C. IgM increase (Correct Answer)
- D. B cell absent
Functional Imaging in Oncology Explanation: ***IgM increase***
- A deficiency in **CD40**, or its ligand **CD40L** (found on T helper cells), disrupts **T-cell-dependent B cell activation** and **class switching**.
- Without proper signaling through CD40/CD40L, B cells cannot undergo **isotype switching** from **IgM** to IgG, IgA, or IgE, leading to elevated IgM levels and deficiencies in other antibody classes.
*IgG increase*
- **IgG levels** would likely be **decreased** in CD40 deficiency due to the impaired ability of B cells to undergo **class switching** from IgM to other antibody isotypes.
- The primary role of CD40/CD40L interaction is to facilitate this class switching process.
*T cell absent*
- **CD40 deficiency** does not directly cause the absence of **T cells**; rather, it affects the ability of T cells to adequately activate B cells.
- T-cell absence or severe dysfunction would be indicative of a different primary immunodeficiency, such as **SCID (Severe Combined Immunodeficiency)**.
*B cell absent*
- **CD40 deficiency** does not result in the absence of **B cells**; B cells are present but are dysfunctional in terms of antibody class switching.
- Conditions like **X-linked agammaglobulinemia (XLA)** are characterized by the absence or severe deficiency of B cells.
Functional Imaging in Oncology Indian Medical PG Question 10: Thiamine deficiency is assessed by:
- A. Serum thiamine level
- B. RBC thiamine levels
- C. Erythrocyte transketolase activity (Correct Answer)
- D. RBC Glutathione reductase
Functional Imaging in Oncology Explanation: ***Erythrocyte transketolase activity***
- This is the **most reliable functional assay** for thiamine deficiency, as thiamine pyrophosphate (TPP) is a crucial cofactor for the enzyme **transketolase**.
- A significant increase in transketolase activity after the addition of TPP *in vitro* indicates a deficiency, demonstrating the enzyme's reliance on exogenous thiamine.
*Serum thiamine level*
- **Serum thiamine levels** can fluctuate and do not accurately reflect the body's thiamine stores or functional status, as most thiamine is intracellular.
- This measurement may be normal even in cases of functional deficiency or tissue depletion.
*RBC thiamine levels*
- While red blood cell (RBC) thiamine levels provide a better estimate of tissue stores compared to serum levels, they are **still less sensitive** than direct functional assays like transketolase activity.
- RBC thiamine measurements do not directly assess the functional impact of thiamine deficiency on metabolic pathways.
*RBC Glutathione reductase*
- **Glutathione reductase** activity is used to assess **riboflavin (vitamin B2) deficiency**, not thiamine.
- Riboflavin in its coenzyme form, **flavin adenine dinucleotide (FAD)**, is a necessary cofactor for glutathione reductase.
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