Imaging of Prostheses and Implants — MCQs

10 questions

Complications of sling procedures (TVT) for USI are all except:

A child presents with painful limp and restricted hip rotation. ESR and CRP are elevated. Initial plain radiograph is normal. What is the next best imaging study?

Which of the following investigations is contraindicated in patients with metallic foreign body?

Objectives of pre-prosthetic surgical procedures include all, except:

What is the most common complication after total hip replacement?

Which one of the following imaging techniques gives the maximum radiation exposure to the patient?

A 40-year-old woman with breast implants presents with breast pain after a recent fall. MRI shows the 'linguine sign.' What does this indicate?

Investigation of choice for lumbar prolapsed disc -

Best investigation to detect rupture of silicone breast implants is-

Q10

In which condition is the cleavage plane sign typically observed?

Imaging of Prostheses and Implants Indian Medical PG Practice Questions and MCQs

Question 1: Complications of sling procedures (TVT) for USI are all except:

A. Obturator nerve injury is about 10% (Correct Answer)
B. Overactive bladder in about 7% cases
C. Injury to bladder and wound haematoma
D. Sling erosion particularly with polytetrafluoroethylene (Goretex)

Explanation: ***Obturator nerve injury is about 10%*** ✓ **CORRECT ANSWER (NOT a complication of TVT)** - **Obturator nerve injury** is exceedingly rare during **TVT (Tension-free Vaginal Tape)** procedures, which use a retropubic approach through the space of Retzius. - This complication is primarily associated with **TOT (Trans-Obturator Tape)** procedures where the tape passes near the obturator foramen, not with standard retropubic TVT. - The incidence of obturator nerve injury in TVT is essentially negligible (<0.1%), nowhere near 10%. *Overactive bladder in about 7% cases* - **De novo overactive bladder (OAB)** symptoms or worsening of pre-existing OAB can occur in 3-15% of patients after TVT procedures, with 7% being a commonly cited figure. - This occurs due to changes in bladder neck support, urethral kinking, or irritation from the sling material. *Injury to bladder and wound haematoma* - **Bladder injury/perforation** occurs in 2-5% of TVT cases due to the retropubic passage of needles close to the bladder, which is why intraoperative cystoscopy is routinely performed. - **Wound hematoma** can occur at the vaginal or suprapubic incision sites as a common surgical complication from tissue dissection and bleeding. *Sling erosion particularly with polytetrafluoroethylene (Goretex)* - **Sling erosion** into the vagina or urethra is a documented complication of synthetic slings, with rates of 0.5-3% for modern materials. - **Polytetrafluoroethylene (Goretex)**, an older first-generation mesh material, was associated with significantly higher rates of erosion (up to 10%) and infection compared to modern monofilament polypropylene meshes, which is why it has been largely discontinued for sling procedures.

Question 2: A child presents with painful limp and restricted hip rotation. ESR and CRP are elevated. Initial plain radiograph is normal. What is the next best imaging study?

A. CT Scan
B. MRI with contrast (Correct Answer)
C. Bone Scan
D. Plain Radiograph

Explanation: ***MRI with contrast*** - An **MRI with contrast** is the most sensitive and specific imaging modality for detecting early changes in **osteomyelitis** or **septic arthritis**, which are serious conditions given the child's symptoms and elevated inflammatory markers. - It can visualize soft tissue and bone marrow edema, joint effusions, and abscesses, guiding immediate treatment. *CT Scan* - While useful for bony detail, a CT scan is **less sensitive than MRI** for detecting early bone marrow changes or soft tissue inflammation in the hip joint. - It also involves **radiation exposure**, which should be limited in children when other effective modalities are available. *Bone Scan* - A bone scan using **technetium-99m** is sensitive for detecting increased bone turnover, but it is **not specific for infection** and cannot differentiate between inflammatory processes, tumors, or fractures. - It provides less anatomical detail compared to MRI, making precise localization of an infection more challenging. *Plain Radiograph* - Plain radiographs are typically the **initial imaging study** for orthopedic complaints but are often **normal in early stages** of septic arthritis or osteomyelitis. - Significant radiographic changes, such as bone erosion or joint space widening, usually appear much later in the disease process.

Question 3: Which of the following investigations is contraindicated in patients with metallic foreign body?

A. CT Scan
B. MRI (Correct Answer)
C. VER
D. ERG

Explanation: ***MRI*** - Magnetic resonance imaging (MRI) uses a powerful **magnetic field** and radio waves to create detailed images of organs and tissues. - The strong magnetic field can cause **ferromagnetic metallic objects** to move, heat up, or malfunction, posing a significant safety risk. *CT Scan* - A CT scan uses **X-rays** to produce cross-sectional images of the body and is generally safe in the presence of metallic foreign bodies. - While metallic objects can cause **artifacts** (streaks or distortions) in CT images, this does not pose a direct safety risk to the patient. *VER* - **Visual Evoked Response (VER)**, also known as VEP (Visual Evoked Potential), is an electrophysiological test that measures the electrical activity of the brain in response to visual stimuli. - It does not involve strong magnetic fields or radiation and is therefore **safe** for patients with metallic foreign bodies. *ERG* - An **Electroretinogram (ERG)** measures the electrical responses of the retina to light stimulation, assessing retinal function. - It is a non-invasive test that does not use magnetic fields or X-rays and is **not contraindicated** in the presence of metallic foreign bodies.

Question 4: Objectives of pre-prosthetic surgical procedures include all, except:

A. All of the above (Correct Answer)
B. Removal of epulis fissuratum
C. Correction of unfavorably located frenular attachments
D. Vestibuloplasty

Explanation: ***All of the above*** - The question asks for what is *not* an objective of pre-prosthetic surgical procedures, and since the specific options provided (removal of epulis fissuratum, correction of unfavorably located frenular attachments, and vestibuloplasty) are indeed common objectives, "All of the above" is the correct choice, indicating that none of these procedures are exceptions to the objectives. - The other options represent specific objectives, meaning that they are *included* in the goals of pre-prosthetic surgery. *Removal of epulis fissuratum* - **Epulis fissuratum** is a hyperplastic tissue growth often caused by ill-fitting dentures, and its removal is a common pre-prosthetic surgical procedure. - Its presence can interfere with **denture stability** and cause discomfort, thus its removal is an important objective. *Correction of unfavorably located frenular attachments* - **Frenular attachments** that are too high or thick can dislodge a denture or cause pain, and their surgical correction (frenectomy) is a standard pre-prosthetic procedure. - This procedure aims to improve **denture retention** and comfort by modifying the soft tissue architecture. *Vestibuloplasty* - **Vestibuloplasty** is a surgical procedure designed to increase the depth of the **vestibule**, which is essential for improving denture stability and retention. - This procedure creates a more favorable anatomical foundation for **denture support**, especially in cases of severe alveolar ridge resorption.

Question 5: What is the most common complication after total hip replacement?

A. Dislocation
B. DVT (Correct Answer)
C. Infection
D. Aseptic Loosening

Explanation: ***DVT*** - Deep vein thrombosis (DVT) is the **most common overall complication** following total hip replacement, with reported incidences as high as 40-60% without prophylaxis. - The risk of DVT is significant due to **venous stasis during surgery**, immobilization, and the inflammatory response to tissue injury. *Dislocation* - While a serious complication, **dislocation** of the prosthetic hip joint is less common than DVT, occurring in about 1-5% of primary total hip replacements. - It typically results from **improper joint positioning** or patient activities that push the hip beyond its normal range of motion. *Infection* - **Infection** is a severe but relatively rare complication, with rates for periprosthetic joint infection in total hip replacement typically ranging from 0.5% to 2%. - It can lead to significant morbidity and usually requires **further surgical intervention** for eradication. *Aseptic Loosening* - **Aseptic loosening** is a long-term complication, occurring years after the surgery, rather than an immediate post-operative complication. - This complication involves the **failure of the implant-bone interface** without evidence of infection, often due to particle disease or mechanical stress.

Question 6: Which one of the following imaging techniques gives the maximum radiation exposure to the patient?

A. Chest X-ray
B. MRI
C. CT scan (Correct Answer)
D. Bone scan

Explanation: ***CT scan*** - **CT scans** involve multiple X-ray projections and computer processing, resulting in a significantly higher radiation dose compared to conventional X-rays. - The effective dose from a single chest or abdominal CT scan can be equivalent to hundreds of standard chest X-rays, making it the highest radiation contributor among the options listed. *Chest X-ray* - A **chest X-ray** uses a very small amount of ionizing radiation, typically one of the lowest doses among diagnostic imaging techniques that involve radiation. - While it uses radiation, its contribution to overall exposure is minimal, especially compared to CT scans. *MRI* - **MRI (Magnetic Resonance Imaging)** uses strong magnetic fields and radio waves to create detailed images of organs and soft tissues, not ionizing radiation. - Therefore, it involves **no radiation exposure** to the patient. *Bone scan* - A **bone scan** uses a small amount of **radioactive tracer** (radionuclide) injected into the bloodstream, which is then detected by a special camera. - While it involves radiation, the dose is generally lower than that of a CT scan and is comparable to or slightly higher than a series of X-rays.

Question 7: A 40-year-old woman with breast implants presents with breast pain after a recent fall. MRI shows the 'linguine sign.' What does this indicate?

A. Fibroadenoma
B. Breast carcinoma
C. Implant rupture (Correct Answer)
D. Breast abscess

Explanation: ***Implant rupture*** - The **"linguine sign"** on MRI is a classic finding for an **intracapsular rupture** of a silicone breast implant, where the collapsed implant shell is seen floating within the silicone gel. - The recent fall and localized breast pain are consistent with a traumatic event leading to implant compromise. *Fibroadenoma* - A fibroadenoma is a **benign solid tumor** of the breast that does not typically cause the "linguine sign." - Its appearance on imaging is usually a well-defined, smooth or lobulated mass, not indicative of implant rupture. *Breast carcinoma* - Breast carcinoma typically presents as an **irregular mass** with spiculations or microcalcifications, and does not cause the "linguine sign." - While breast pain can be a symptom, the specific MRI finding points away from malignancy. *Breast abscess* - A breast abscess is a localized collection of **pus**, usually presenting with signs of infection such as redness, warmth, and fever, along with a focal fluctuating mass. - It would appear as a fluid collection on MRI, but not with the characteristic "linguine sign" of implant rupture.

Question 8: Investigation of choice for lumbar prolapsed disc -

A. CT Scan
B. Myelogram
C. X-ray
D. MRI (Correct Answer)

Explanation: ***MRI*** - An **MRI** provides the best visualization of **soft tissues**, including the intervertebral discs, spinal cord, and nerve roots, making it the **gold standard** for diagnosing lumbar prolapsed disc. - It can accurately show the **degree of disc herniation**, its impact on neural structures, and associated edema, which are crucial for treatment planning. *CT Scan* - While a **CT scan** provides good bony detail and can show disc herniation, its ability to visualize soft tissues is inferior to MRI for this specific condition. - It involves **ionizing radiation** and may miss subtle nerve root compression or spinal cord abnormalities apparent on MRI. *Myelogram* - A **myelogram** involves injecting contrast dye into the spinal canal and then performing X-rays or CT scans to outline the spinal cord and nerve roots. - Though effective in showing **nerve compression**, it is an **invasive procedure** with potential complications and has largely been replaced by MRI as a first-line diagnostic investigation. *X-ray* - **X-rays** primarily visualize **bony structures** and are useful for detecting fractures, spinal alignment issues, or severe degenerative changes. - They **cannot directly visualize intervertebral discs** or nerve compression, making them unsuitable for diagnosing a prolapsed disc.

Question 9: 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 10: 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.

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