AI Applications in Musculoskeletal Imaging — MCQs
Identify the imaging modality given below.
Which imaging modality is LEAST useful in the initial diagnosis of stress fractures?
What is the investigation of choice for diagnosing a stress fracture?
Based on the provided image, which of the following is the correct diagnosis?
Gold standard investigation for breast carcinoma screening in a patient with silicone breast implants
Earliest investigation for diagnosis of Ankylosing spondylitis:
Classification system of bone tumors is -
According to American College of Rheumatology, all of the following are clinical criteria for the diagnosis of osteoarthritis, EXCEPT:
In which condition is the cleavage plane sign typically observed?
Which of the following bone lesions is characterized by the 'fallen fragment sign,' a radiological feature seen in lytic bone lesions with fluid-filled cavities?
AI Applications in Musculoskeletal Imaging Indian Medical PG Practice Questions and MCQs
Question 1: Identify the imaging modality given below.
- A. USG (Correct Answer)
- B. Fluoroscopy
- C. X-Ray
- D. MRI
Explanation: ***USG*** - The image displays characteristic **gray-scale imaging** with an **echogenic appearance** of tissues, typical of an ultrasound. - Presence of annotations like "10 MHz G 64%" for **frequency and gain**, and "PRC" suggest ultrasound parameters. *Fluoroscopy* - Fluoroscopy provides **real-time X-ray images** and often involves the use of contrast agents, appearing as a dynamic, darker image with high contrast. - The image lacks the distinct bone and air contrast and dynamic motion typical of fluoroscopy. *X-Ray* - X-ray images depict a **static shadowgram** of dense structures like bones as white, and air as black, with sharp delineation. - The image shows a **granular texture** and fluid-filled structures that are characteristic of soft tissue imaging through ultrasound, not X-ray. *MRI* - MRI produces **cross-sectional images** with high soft tissue contrast in multiple planes (axial, sagittal, coronal). - The image shows real-time B-mode ultrasound characteristics with **probe frequency notation**, not the slice-based imaging of MRI.
Question 2: Which imaging modality is LEAST useful in the initial diagnosis of stress fractures?
- A. MRI
- B. Bone scan
- C. X ray
- D. CT (Correct Answer)
Explanation: ***Correct: CT*** - While **CT** can show bony details, it is **less sensitive** than MRI or bone scan for early stress fractures, which often involve subtle marrow edema or periosteal reaction - Its primary role is usually in defining **fracture geometry** or evaluating **fracture healing**, not initial detection - **CT is rarely used as a first-line imaging modality** for suspected stress fractures *Incorrect: MRI* - **MRI** is highly sensitive for **stress fractures**, detecting early changes such as **marrow edema** and **periosteal reaction** before they are visible on X-ray - It is considered the **gold standard** for confirming a stress fracture when initial X-rays are negative - This is one of the MOST useful modalities, not the least *Incorrect: Bone scan* - **Bone scintigraphy** (bone scan) is very sensitive for **stress fractures**, as it detects increased **osteoblastic activity** at the site of injury - It can identify stress fractures long before they are visible on plain radiographs, showing a focal area of increased radiotracer uptake - This is highly useful for initial diagnosis, not the least useful *Incorrect: X-ray* - **Plain radiographs (X-rays)** are often the **initial imaging modality** for suspected stress fractures due to availability and cost - However, they have **low sensitivity in the early stages** - early stress fractures may appear normal on X-ray - Visible signs such as **sclerosis, periosteal reaction**, or a **fracture line** only develop several weeks after symptom onset - Despite low sensitivity, X-ray is still more commonly used for initial evaluation than CT
Question 3: What is the investigation of choice for diagnosing a stress fracture?
- A. X-ray
- B. CT scan
- C. MRI (Correct Answer)
- D. Bone scan
Explanation: ***MRI*** - **Magnetic Resonance Imaging (MRI)** is the most sensitive and specific imaging modality for diagnosing **stress fractures**, especially in their early stages. - It can detect **bone marrow edema** and **periosteal reactions** indicative of stress injury before cortical changes are visible on plain radiographs. *X-ray* - **X-rays** are often the initial investigation, but they have low sensitivity for **stress fractures** in the early stages as bone changes may not be apparent for several weeks. - A positive X-ray for stress fracture typically shows a **sclerotic line** or **periosteal reaction**, but this indicates a more advanced injury. *CT scan* - **CT scans** provide excellent detail of **cortical bone** and can detect subtle fractures not seen on X-rays. - While more sensitive than X-rays, CT has **higher radiation exposure** and is generally less sensitive than MRI for early detection of **bone marrow edema** associated with stress injuries. *Bone scan* - **Bone scans** (scintigraphy) are highly sensitive for detecting increased **osteoblastic activity** associated with stress fractures. - However, they are **less specific** as various conditions can cause increased uptake, and they do not provide detailed anatomical information, making MRI superior for definitive diagnosis and staging.
Question 4: Based on the provided image, which of the following is the correct diagnosis?
- A. Uterus didelphys
- B. Bicornuate Uterus
- C. Unicornuate Uterus (Correct Answer)
- D. Septate uterus
Explanation: ***Unicornuate Uterus*** - The image distinctly shows **only one fallopian tube and one rudimentary uterine horn** on the right side, indicating a unicornuate uterus. - This malformation results from the **incomplete development of one Müllerian duct**, leading to a single, banana-shaped uterine cavity. *Uterus didelphys* - This condition involves **two completely separate uteri**, each with its own cervix and vagina. - The image does not show evidence of two distinct uterine bodies or cervices. *Bicornuate Uterus* - A bicornuate uterus is characterized by **two uterine horns that fuse caudally**, creating a heart-shaped appearance with a shared cervix. - The image clearly lacks the characteristic heart shape and shows only one functional horn. *Septate uterus* - A septate uterus has a **fibrous or muscular septum** dividing the uterine cavity, while the external uterine contour remains normal. - The image does not show a septum or a normal external uterine contour with an internal division; instead, it presents with a single underdeveloped horn.
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: Earliest investigation for diagnosis of Ankylosing spondylitis:
- A. CT scan
- B. Bone scan
- C. X-ray
- D. MRI STIR sequence (Correct Answer)
Explanation: ***MRI STIR sequence*** - An **MRI STIR (Short Tau Inversion Recovery) sequence** is highly sensitive for detecting early inflammatory changes in the **sacroiliac joints** and spine, such as **bone marrow edema**, which is a hallmark of early ankylosing spondylitis. - It can identify disease activity and structural changes *before* they are visible on conventional X-rays, making it the earliest diagnostic tool. *CT scan* - While a **CT scan** provides excellent detailed images of bone, it is not as sensitive as MRI for detecting early inflammatory changes like **bone marrow edema** in the sacroiliac joints. - It involves significant **radiation exposure** and is typically used for more advanced structural assessment rather than early diagnosis. *Bone scan* - A **bone scan** (scintigraphy) shows areas of increased bone turnover but is **not specific** for ankylosing spondylitis and has lower spatial resolution compared to MRI. - It can indicate inflammation or increased metabolic activity but cannot differentiate specific causes or provide detailed anatomical information as effectively as MRI. *X-ray* - **X-rays** are often the initial imaging modality due to their accessibility, but they only show **structural changes** (like erosions, sclerosis, or fusion) in the sacroiliac joints and spine at a later stage of the disease. - Early inflammatory changes, such as **bone marrow edema**, are typically not visible on plain radiographs, leading to a delay in diagnosis compared to MRI.
Question 7: Classification system of bone tumors is -
- A. Enneking (Correct Answer)
- B. Edmonton
- C. TNM
- D. Manchester
Explanation: ***Enneking*** - The **Enneking staging system** is widely used for primary **bone tumors**, particularly sarcomas. - It classifies tumors based on their histological grade, local extension, and presence of metastases, which guides surgical planning and prognosis. *Edmonton* - The **Edmonton classification** is primarily used for **periprosthetic fractures** around hip and knee replacements. - It does not classify primary bone tumors but rather describes fracture patterns related to prosthetic implants. *TNM* - The **TNM (Tumor, Node, Metastasis)** classification is a general staging system used for many types of cancer, but it's not the primary system for bone tumors. - While applicable for some bone cancers, the **Enneking system** provides a more specific functional and anatomical assessment for limb-sparing surgery in bone sarcomas. *Manchester* - The **Manchester staging system** is primarily used for **lymphoma**, particularly Hodgkin lymphoma. - It describes the extent of lymph node involvement and extralymphatic disease, completely unrelated to bone tumors.
Question 8: According to American College of Rheumatology, all of the following are clinical criteria for the diagnosis of osteoarthritis, EXCEPT:
- A. Lack of warmth
- B. Crepitus
- C. Atrophy of quadriceps muscles (Correct Answer)
- D. Age > 50 years
Explanation: ### Atrophy of quadriceps muscles - While muscle weakness can be a consequence of **osteoarthritis (OA)** due to pain and disuse, **quadriceps atrophy** is not a primary diagnostic criterion according to the American College of Rheumatology (ACR) criteria for OA. Local examination of the knee in OA may frequently reveal weakness and wasting of the quadriceps muscle [1]. - The ACR criteria primarily focus on patient symptoms, physical exam findings, and radiographic evidence to define OA. ### Lack of warmth - This is a typical physical finding in osteoarthritis, as **inflammation** is generally mild or absent compared to inflammatory arthropathies, thus joints are usually **not warm** to the touch. - It helps differentiate OA from conditions like septic arthritis or gout, where warmth is a prominent feature. ### Crepitus - **Crepitus**, or crackling/grating sounds during joint movement, is a classic clinical finding in osteoarthritis, indicating a roughened articular surface. Examination often reveals restricted flexion/extension accompanied by coarse crepitus [1]. - It is one of the key clinical signs used in the ACR criteria for OA, especially when combined with other symptoms like pain and stiffness. ### Age > 50 years - **Age over 50 years** is a significant risk factor and a clinical criterion for diagnosing osteoarthritis, as the prevalence of OA increases with age. While typical symptoms usually present after age 45-50, early-onset OA is rare and often linked to trauma [1]. - The ACR criteria often incorporate age as a factor when considering symptomatic OA.
Question 9: In which condition is the cleavage plane sign typically observed?
- A. Parosteal osteosarcoma (Correct Answer)
- B. Ewing's sarcoma
- C. Chondrosarcoma
- D. Metastasis
Explanation: ***Parosteal osteosarcoma*** - The **cleavage plane sign** refers to the presence of a fat-filled or fibrous plane separating the tumor from the underlying cortex, which is characteristic of **parosteal osteosarcoma**. - This sign indicates the **juxtacortical (parosteal) growth pattern** of the tumor, which begins on the bone surface and typically grows outwards. *Ewing's sarcoma* - **Ewing's sarcoma** is a highly aggressive malignant bone tumor that originates in the bone marrow, often presenting with an **"onion-skin" periosteal reaction** due to its intramedullary growth. - It does not typically exhibit a clear cleavage plane between the tumor and the cortex as it grows from within the bone. *Chondrosarcoma* - **Chondrosarcoma** is a malignant tumor of cartilage, often showing **popcorn-like calcifications** and endosteal scalloping, indicating its cartilaginous matrix and intramedullary growth. - While it can be juxtacortical, it does not typically present with a distinct fat or fibrous cleavage plane from the underlying bone like parosteal osteosarcoma. *Metastasis* - **Bone metastases** are secondary cancers that have spread to the bone, often presenting as **lytic or blastic lesions** depending on the primary tumor type. - These lesions typically originate within the bone marrow and invade the bone structure, rather than growing from the surface with a distinct cleavage plane.
Question 10: Which of the following bone lesions is characterized by the 'fallen fragment sign,' a radiological feature seen in lytic bone lesions with fluid-filled cavities?
- A. Adamantinoma
- B. Aneurysmal bone cyst
- C. Simple bone cyst (Correct Answer)
- D. Osteosarcoma
Explanation: ***Simple bone cyst*** - The **'fallen fragment sign'** is a **pathognomonic radiological feature** of simple bone cysts (unicameral bone cysts). - This sign occurs when a **pathological fracture** through the cyst allows a fragment of cortical bone to fall into the fluid-filled cavity and settle dependently at the bottom, visible on upright radiographs. - Simple bone cysts are benign, fluid-filled lesions commonly affecting the **proximal humerus and proximal femur** in children and adolescents. *Aneurysmal bone cyst* - This is a **benign, blood-filled, expansile lesion** with multiple septated compartments. - Characteristic radiological feature is **fluid-fluid levels** on MRI or CT due to blood products of different densities. - Does NOT typically demonstrate the 'fallen fragment sign' - the multi-loculated nature prevents free-floating bone fragments. *Adamantinoma* - This rare **malignant bone tumor** primarily affects the **tibia** and presents as a lytic lesion, often with sclerotic borders. - It is a solid tumor that does not form simple fluid-filled cavities or demonstrate the 'fallen fragment sign.' *Osteosarcoma* - This is a **highly malignant bone tumor** characterized by osteoid production and bone destruction. - Often presents with periosteal reaction like a **'sunburst' pattern or Codman's triangle**. - It is a solid, aggressive tumor that does not form fluid-filled cavities that would exhibit a 'fallen fragment sign.'
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