Breast MRI — MCQs
ACR score 4 in breast imaging indicates
Which of the following features on mammogram would suggest malignancy?
Which of the following features suggests a malignant lesion on mammography?
Which of the following breast lesions characteristically shows central necrosis with calcification?
Gold standard investigation for breast carcinoma screening in a patient with silicone breast implants
Best investigation to detect rupture of silicone breast implants is-
For normal mammography, what is the nominal focal size of the X-ray tube used?
What is the typical radiation dose delivered during mammography?
Which of the following is NOT an indicator of malignancy on mammography?
Which of the following is NOT an indication of malignancy on mammography?
Breast MRI Indian Medical PG Practice Questions and MCQs
Question 1: ACR score 4 in breast imaging indicates
- A. Probably benign
- B. Highly suggestive of malignancy
- C. Negative
- D. Suspicious abnormality (Correct Answer)
Explanation: ***Suspicious abnormality*** - An **ACR BI-RADS category 4** indicates a **suspicious abnormality** that necessitates a biopsy to rule out malignancy. - The risk of malignancy in this category ranges from **2% to 94%**, representing findings that do not have the classic appearance of malignancy but have a definite probability of being cancer. *Probably benign* - This description corresponds to an **ACR BI-RADS category 3**, which suggests a less than 2% chance of malignancy. - Category 3 findings are usually followed up with **short-term interval imaging** (e.g., 6 months) to assess stability. *Highly suggestive of malignancy* - This corresponds to an **ACR BI-RADS category 5**, where the findings almost certainly represent **malignancy** (at least 95% probability). - Category 5 lesions require **appropriate action**, such as biopsy or definitive treatment, based on the highest level of suspicion. *Negative* - This description is for an **ACR BI-RADS category 1**, meaning there are **no significant findings** and the breast is normal. - Category 1 indicates that the study is completed and no further action is needed beyond routine screening.
Question 2: Which of the following features on mammogram would suggest malignancy?
- A. Smooth borders
- B. Well defined lesion
- C. A mass of decreased density
- D. Areas of spiculated microcalcifications (Correct Answer)
Explanation: ***Areas of spiculated microcalcifications*** - **Spiculated microcalcifications** are highly suspicious for malignancy due to their irregular shape, distribution, and association with rapid, uncontrolled cell growth. - These calcifications often represent **necrotic cells** within rapidly growing tumors, which can deposit calcium. *Smooth borders* - **Smooth borders** typically indicate a benign lesion, such as a cyst or fibroadenoma, as they suggest gradual, uniform growth rather than invasive spread. - Malignant lesions tend to have **irregular** or ill-defined borders due to their infiltrative nature. *Well defined lesion* - A **well-defined lesion** usually suggests a benign process, as it indicates a mass that is clearly demarcated from surrounding tissue and is likely encapsulated. - Malignancies, conversely, often exhibit **indistinct or irregular margins** as they invade adjacent structures. *A mass of decreased density* - A mass of **decreased density** is generally considered a benign finding, often representing a **cyst** or an area of normal fatty tissue. - Malignant tumors typically present as a **mass of increased density** due to their cellular proliferation and desmoplastic reaction.
Question 3: Which of the following features suggests a malignant lesion on mammography?
- A. Macrocalcifications
- B. Microcalcifications (Correct Answer)
- C. Fat content
- D. Round well defined borders
Explanation: ***Microcalcifications*** - **Fine, pleomorphic, branching, or linear calcifications** clustered together are highly suspicious for malignancy, particularly **ductal carcinoma in situ (DCIS)**. - They represent calcium deposits within the ducts or stromal calcifications related to tumor cells. *Macrocalcifications* - These are **larger, coarser calcifications** (typically >0.5 mm) which are almost universally benign. - They are often associated with benign conditions such as **fibroadenomas**, old trauma, or vascular calcifications. *Fat content* - Lesions predominantly composed of fat, such as **lipomas**, **oil cysts**, and **hamartomas**, are typically benign. - The presence of fat within a lesion on mammography generally indicates a **benign process**. *Round well defined borders* - A **smooth, rounded, and well-circumscribed margin** on mammography is a strong indicator of a benign lesion. - Malignant lesions typically have **irregular, spiculated, or ill-defined margins** due to invasive growth.
Question 4: Which of the following breast lesions characteristically shows central necrosis with calcification?
- A. Cribriform sub type of DCIS
- B. Lobular carcinoma in situ
- C. Colloid carcinoma
- D. Comedo sub type of DCIS (Correct Answer)
Explanation: ***Comedo sub type of DCIS*** - This subtype is characterized by high-grade pleomorphic tumor cells with **central necrosis** within the ducts [1]. - The necrotic debris often calcifies, leading to characteristic **microcalcifications** visible on mammograms [2]. *Cribriform sub type of DCIS* - This subtype features uniform cells forming gland-like spaces within the ducts, but **typically lacks significant central necrosis** and extensive calcification [1]. - It usually presents with a **low nuclear grade** and less aggressive features compared to comedo DCIS [1]. *Lobular carcinoma in situ* - Characterized by small, discohesive cells filling and expanding the acini of the lobules, but it **does not involve ductal necrosis or calcification**. - It is often an **incidental finding** and represents a marker for increased risk of invasive carcinoma in either breast, rather than an obligate precursor lesion visible with calcifications. *Colloid carcinoma* - This is a type of **invasive ductal carcinoma** where tumor cells float in abundant extracellular mucin. - While it is an invasive cancer, it does not typically present with the extensive **ductal necrosis and calcification** seen in comedo DCIS. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1062-1064. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 452-453.
Question 5: 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)
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.
Question 6: Best investigation to detect rupture of silicone breast implants is-
- A. Mammography
- B. X-ray
- C. MRI (Correct Answer)
- D. USG
Explanation: ***MRI*** - **Magnetic Resonance Imaging (MRI)** is considered the **gold standard** for detecting silicone breast implant ruptures due to its superior soft tissue contrast and ability to differentiate silicone from other tissues. - It can accurately identify both **intracapsular** (linguine sign) and **extracapsular** ruptures, as well as associated silicone granulomas. *Mammography* - While useful for breast cancer screening, **mammography** has limited sensitivity for detecting silicone implant ruptures, especially subtle ones. - It can show indirect signs like implant contour abnormalities or increased implant density but is often inconclusive for rupture diagnosis. *X-ray* - **X-rays** provide very little information regarding the integrity of silicone breast implants because silicone is radiolucent and does not show up clearly on standard radiographs. - Its utility is primarily for detecting calcifications or foreign bodies, not implant rupture. *USG* - **Ultrasound (USG)** can be a useful initial screening tool for detecting implant ruptures, showing signs like the **"stepladder sign"** for intracapsular rupture or anechoic collections (silicone outside the capsule). - However, its accuracy is highly operator-dependent, and it may miss subtle ruptures or be limited by poor visualization due to scar tissue, making MRI a more definitive choice.
Question 7: For normal mammography, what is the nominal focal size of the X-ray tube used?
- A. 0.2-0.25 mm
- B. 0.3-0.35 mm (Correct Answer)
- C. 0.4-0.45 mm
- D. 0.45-0.50 mm
Explanation: In mammography, high spatial resolution is critical for detecting tiny structures like microcalcifications. The focal spot size directly influences **geometric blurring** (penumbra); a smaller focal spot results in a sharper image. ### 1. Why Option B is Correct For **routine (normal) mammography**, a nominal focal spot size of **0.3 mm** (typically ranging from 0.3 to 0.35 mm) is the standard. This size provides an optimal balance: it is small enough to ensure high detail for screening while being large enough to withstand the heat generated by the X-ray tube during standard exposures without damaging the anode. ### 2. Why Other Options are Incorrect * **Option A (0.2-0.25 mm):** This is too large for magnification but smaller than the standard for routine screening. * **Options C & D (0.4-0.5 mm):** These sizes are used in general radiography (e.g., Chest X-rays, where focal spots are often 0.6–1.2 mm). In mammography, such large spots would cause excessive geometric blurring, making it impossible to see fine architectural distortions. ### 3. High-Yield Clinical Pearls for NEET-PG * **Magnification Mammography:** When a specific area needs to be magnified, a much smaller focal spot of **0.1 mm** (range 0.1–0.15 mm) is used to compensate for the increased blurring caused by the air gap. * **Anode Material:** Usually **Molybdenum (Mo)** or Rhodium (Rh) is used to produce low-energy (soft) X-rays (25–30 kVp) for better soft-tissue contrast. * **Orientation:** The cathode is placed over the **base of the breast** (chest wall) and the anode over the **apex** (nipple) to utilize the "Heel Effect" for uniform density.
Question 8: What is the typical radiation dose delivered during mammography?
- A. 0.1 Gray/study
- B. 0.01 centiGray/study
- C. 0.1 centiGray/study (Correct Answer)
- D. 0.01 Gray/study
Explanation: ### Explanation **1. Why Option C is Correct:** The radiation dose in mammography is measured as the **Mean Glandular Dose (MGD)**, which represents the average dose to the radiosensitive glandular tissue of the breast. For a standard two-view screening mammogram (per breast), the typical dose is approximately **1 to 2 mGy (0.1 to 0.2 rad)**. Since **1 rad = 1 centiGray (cGy)**, a dose of 0.1 rad is equivalent to **0.1 cGy**. This level of radiation is considered very low and is roughly equivalent to the amount of natural background radiation a person receives over seven weeks. **2. Why Other Options are Incorrect:** * **Option A (0.1 Gray):** This is equivalent to 100 mGy. This dose is far too high for diagnostic imaging and would be closer to levels used in therapeutic radiation or causing deterministic effects. * **Option B (0.01 cGy):** This is 0.1 mGy, which is too low to produce a diagnostic quality image of dense breast tissue. * **Option D (0.01 Gray):** This is equivalent to 10 mGy (1 rad). While some complex interventional procedures might reach this level, it is significantly higher than the standard dose for a screening mammogram. **3. High-Yield Clinical Pearls for NEET-PG:** * **Target/Filter Material:** Mammography uses low-energy X-rays (typically **25–35 kVp**) to maximize soft tissue contrast. Common target/filter combinations are **Molybdenum/Molybdenum** or **Rhodium**. * **MQSA Requirement:** The Mammography Quality Standards Act (MQSA) mandates that the dose should not exceed **3 mGy (0.3 cGy)** per view with a grid. * **Screening Guidelines:** In India, the general recommendation is annual or biennial screening starting at age 40–50 years. * **Risk vs. Benefit:** The risk of radiation-induced breast cancer is negligible compared to the benefit of early detection of spontaneous breast cancer.
Question 9: Which of the following is NOT an indicator of malignancy on mammography?
- A. Nodular calcification (Correct Answer)
- B. Speckled margin
- C. Attenuated architecture
- D. Irregular mass
Explanation: **Explanation:** In mammography, distinguishing between benign and malignant lesions depends on analyzing mass morphology, margins, and calcification patterns. **1. Why "Nodular Calcification" is the correct answer:** Nodular (or "popcorn-like") calcifications are typically large, coarse, and well-defined. These are classic features of **benign** lesions, most commonly seen in involuting **fibroadenomas**. Malignant calcifications, by contrast, are usually pleomorphic (variable shapes), fine-linear, or branching (casting), representing necrosis within ducts (e.g., DCIS). **2. Analysis of Incorrect Options (Indicators of Malignancy):** * **Speckled (Spiculated) Margin:** This is the most specific mammographic sign of malignancy. It represents the desmoplastic reaction of the surrounding tissue as the tumor invades. * **Attenuated (Distorted) Architecture:** Architectural distortion occurs when the normal radial septa of the breast are pulled or straightened. In the absence of a history of trauma or surgery, this is highly suspicious for invasive breast cancer. * **Irregular Mass:** Malignant tumors grow haphazardly, leading to an irregular shape rather than a smooth, round, or oval appearance (which favors benignity). **Clinical Pearls for NEET-PG:** * **BI-RADS Classification:** Used for standardized reporting. BI-RADS 5 indicates >95% risk of malignancy. * **Most common benign calcification:** Popcorn-like (Fibroadenoma). * **Most common malignant calcification:** Fine pleomorphic or fine-linear branching. * **Skin Changes:** Skin thickening (>2mm) and nipple retraction are secondary signs of malignancy. * **Screening:** Mammography is the gold standard for screening, but Ultrasound is the investigation of choice for women <35 years due to dense breast tissue.
Question 10: Which of the following is NOT an indication of malignancy on mammography?
- A. Nodular calcification (Correct Answer)
- B. Speckled margin
- C. Attenuated architecture
- D. Irregular mass
Explanation: ### Explanation In mammography, the primary goal is to differentiate between benign and malignant features based on mass morphology, margins, and calcification patterns. **1. Why "Nodular Calcification" is the correct answer:** Nodular (or "popcorn-like") calcifications are typically large, coarse, and well-defined. These are classic features of **benign** lesions, most commonly seen in **involuting fibroadenomas**. Malignant calcifications, by contrast, are usually pleomorphic, fine-linear, or branching (casting type), representing necrotic debris within ducts (as seen in DCIS). **2. Analysis of Incorrect Options (Malignant Features):** * **Speckled (Spiculated) Margin:** This is the most specific mammographic sign of malignancy. It represents the infiltration of cancer cells into surrounding tissue and the subsequent desmoplastic reaction. * **Attenuated (Distorted) Architecture:** Architectural distortion refers to the pulling or tethering of normal breast parenchyma without a visible central mass. While it can occur in post-surgical scars, in a screening context, it is highly suspicious for invasive lobular or ductal carcinoma. * **Irregular Mass:** Malignant tumors grow haphazardly, leading to an irregular shape. Benign lesions are more likely to be round, oval, or circumscribed. **3. High-Yield Clinical Pearls for NEET-PG:** * **BI-RADS Classification:** Used for standardized reporting. BI-RADS 4 and 5 indicate high suspicion of malignancy. * **Most specific sign of malignancy:** Spiculated margins. * **Benign Calcifications:** Popcorn (Fibroadenoma), Eggshell/Rim (Oil cysts), and Teardrop (Milk of calcium). * **Malignant Calcifications:** Fine pleomorphic or fine-linear branching (BI-RADS 5). * **Initial Investigation:** Mammography is the gold standard for screening women >40 years; Ultrasound is preferred for women <30 years or during pregnancy/lactation.
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