RadCases Q&A Musculoskeletal Radiology (eBook)

Case Questions and Answers

The questions and answers in the following section are numbered as cases 1 through 100. The questions correspond to the respectively numbered case reviews and are intended to be answered after working through the cases.

Case 1

1. All of the following statements regarding bisphosphonate fractures are true except…

a) Most patients on bisphosphonate therapy for osteoporosis will not experience this complication.

b) Bisphosphonates suppress osteoclast activity and inhibit bone resorption.

c) The typical duration of drug use before this complication arises is ~1 year.

d) Patients with bisphosphonate fractures may require femoral orthopedic hardware stabilization.

The correct answer is (c). The average duration of bisphosphonate usage before potentially developing insufficiency fractures is ~7 years.

2. What is the proposed mechanism by which these fractures occur?

a) Oversuppression of bone turnover and suppressed bony remodeling resulting in skeletal fragility

b) Blockage of intestinal vitamin D resorption

c) Phosphate wasting

d) Failure of vitamin D hydroxylation

The correct answer is (a). Extended bisphosphonate therapy is believed to inhibit bone turnover and remodeling, resulting in increased skeletal fragility.

Case 2

1. Regarding the acoustic shadowing of a foreign body, which of the following statements is true?

a) Foreign body composition determines the extent of shadowing.

b) Surface contour is the primary determinant of acoustic shadowing.

c) Foreign body acoustic shadowing is always present.

d) None of the above is true.

The correct answer is (b). Shadowing artifacts from foreign bodies is dependent upon the surface contour of the foreign body rather than the foreign body composition. Smooth and flat surfaces produce dirty shadowing, whereas irregular surfaces with a small radius produce clean shadowing. Not all foreign bodies cause acoustic shadowing.

2. Primary advantages of ultrasound evaluation of foreign bodies compared with other imaging modalities include which of the following?

a) Affordability

b) Lack of radiation

c) Availability

d) Portability

e) All of the above

The correct answer is (e). Ultrasound imaging has become the standard of care for evaluation of superficial foreign body detection. Features that make ultrasound imaging the ideal choice include its affordability, portability, availability, and absence of irradiation.

Case 3

1. Demonstration of a meniscal flounce requires which of the following?

a) Imaging of the contralateral knee given the increased incidence of bilaterality

b) Increased suspicion for meniscocapsular injury and other ligamentous injuries

c) Detailed description with implication of a superimposed meniscal tear

d) MR arthrography

The correct answer is (b). The majority of cases of meniscal flounce relate to a normal variant secondary to positioning. However, a diligent search for coexisting pathology is mandatory when flouncing is detected, given that ligamentous injury, meniscal tears, and capsular laxity may exaggerate this wrinkling phenomenon.

2. Theoretically, injury to all of the following structures may lead to lateral meniscal flouncing except…

a) Anterior inferior popliteal meniscal fascicle

b) Posterior superior popliteal meniscal fascicle

c) Ligament of Wrisberg

d) Lateral collateral ligament (LCL)

e) Meniscal homologue

The correct answer is (e). The popliteal meniscal fascicles, the LCL, and the meniscal femoral ligaments have an intimate association with the lateral meniscus and are important for its functioning and stability. As a result, injury to these structures may result in altered mobility of the lateral meniscus predisposing to flouncing. The meniscal homologue is located in the wrist and serves as a stabilizer of the ulnar collateral ligament complex.

Case 4

1. Regarding wrist arthrography, which of the following is true?

a) A 25-gauge needle is the best choice for injection.

b) The ideal injection volume for the distal radial ulnar joint (DRUJ) is 1 to 2 mL.

c) The ideal injection volume for the radiocarpal joint is 8 to 10 mL.

d) None of the above

e) Both a and b

The correct answer is (e). The ideal volume of injection for the radiocarpal compartment is 3 to 4 mL. The ideal injection volume for the distal radial ulnar joint (DRUJ) is 1 to 2 mL. The optimal needle size is a 25-gauge needle which minimizes patient discomfort. Additionally, wrist arthrography injections should avoid the site of symptoms in an effort to prevent iatrogenic disruption of the normal anatomy from the injection.

2. The optimal MR arthrography sequences for wrist internal derangements include all of the following except…

a) T1 fat-suppressed images

b) T2 fat-suppressed images

c) Thin-slice 3D dual-echo steady-state precession (DESSP)

d) Diffusion-weighted imaging

The correct answer is (d). Diffusion-weighted imaging has no role in TFC imaging. Fat-suppressed T1-weighted imaging is designed to provide optimal contrast resolution on MR arthrography. T2-weighted fat-suppressed imaging allows detection of bone marrow abnormalities. Thin-slice 3D DESSP imaging allows detailed analysis of the thin ligaments of the wrist.

3. Regarding triangular fibrocartilage (TFC) tears, which of the following statements is true?

a) Tears frequently occur through the membranous segment.

b) Pseudo-tears may occur adjacent to the radial attachment.

c) Tears along the ulnar attachment have a favorable outcome given increased vascularity.

d) All of the above are true.

The correct answer is (d). TFC tears frequently occur through the membranous segment and tend to be symptomatic if they occur along the undersurface. TFC pseudo-tears may be erroneously diagnosed secondary to volume averaging between the hyaline cartilage of the distal radius and the radial insertional fibers of the TFC. Given the hypervascularity of the ulnar insertional fibers of the TFC, this segment of the TFC exhibits optimal healing.

Case 5

1. Which of the following statements is true regarding desmoid tumors?

a) Notorious for local recurrence after resection

b) Thought to be associated with pregnancy and trauma

c) Typically painless lesion

d) No metastatic potential

e) All of the above are true

The correct answer is (e). Desmoid tumors are frequently seen in women of childbearing age and may have an association with trauma. This relatively painless neoplasm can have a high level of local recurrence after resection. There have been no reported cases of metastasis associated with desmoid tumors.

2. All of the following are potential treatment options for desmoid tumors except…

a) Wide local excision

b) Radiation therapy

c) Laser ablation

d) Chemotherapy

The correct answer is (c). The most widely accepted treatment option for desmoid tumors is wide local excision, which minimizes chances of recurrence. Radiation therapy has been utilized for recurrent lesions and lesions located in anatomically complex locations. Success has been seen with variable chemotherapeutic regimens, particularly in patients with Gardner's syndrome. Laser ablation therapy is not a recognized form of desmoid treatment to date.

Case 6

1. All of the following may be seen on radiographs of patients with renal osteodystrophy except…

a) Sacroiliac joint erosions

b) Rugger jersey spine

c) Diffuse skeletal sclerosis

d) High-riding humeral heads

e) “Salt-and-pepper” appearance of the skull

The correct answer is (d). High-riding humeral heads is a finding that coexists with rotator cuff tearing. This is frequently seen in patients with rheumatoid arthritis and calcium pyrophosphate dihydrate (CPPD) arthropathy. Sacroiliac joint subchondral erosions are a common feature of renal osteodystrophy. Additionally, bandlike sclerosis along the vertebral body end plates is another feature seen with this diagnosis and is referred to as rugger jersey spine. Calvarial trabecular bone resorption results in a “salt-and-pepper” appearance to the skull. Sclerotic changes within the skeleton may also be seen with renal osteodystrophy.

2. Expected imaging findings of patients with renal osteodystrophy include all of the following except…

a) Renal atrophy

b) Extensive vascular calcifications

c) Extensive temporal lobe sclerosis

d) Pericapsular juxta-articular calcific deposits

The correct answer is (c). Sclerosis of the temporal lobes of the brain is not a feature of this disease. However, the calcium and phosphate derangements associated with renal osteodystrophy account for the vascular and soft tissue metastatic calcific deposits. Additionally, the primary insult driving the pathophysiology of renal osteodystrophy is chronic renal disease, with renal atrophy frequently demonstrated on imaging.

Case 7

1. The characteristic soft tissue findings associated with this disease process may be best described by which of the following?

a) Particle disease

b) Aseptic lymphocytic vasculitis–associated lesion (ALVAL)

c) Caseating...