Pelvic radiologic landmarks US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Pelvic radiologic landmarks. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Pelvic radiologic landmarks US Medical PG Question 1: A 36-year-old male is taken to the emergency room after jumping from a building. Bilateral fractures to the femur were stabilized at the scene by emergency medical technicians. The patient is lucid upon questioning and his vitals are stable. Pain only at his hips was elicited. Cervical exam was not performed. What is the best imaging study for this patient?
- A. AP and lateral radiographs of hips
- B. Lateral radiograph (x-ray) of hips
- C. Magnetic resonance imaging (MRI) of hips, knees, lumbar, and cervical area
- D. Anterior-posterior (AP) and lateral radiographs of hips, knees, lumbar, and cervical area
- E. Computed tomography (CT) scan of cervical spine, hips, and lumbar area (Correct Answer)
Pelvic radiologic landmarks Explanation: ***Computed tomography (CT) scan of cervical spine, hips, and lumbar area***
- In **high-energy trauma** (fall from height), a CT scan is the **gold standard** for evaluating the **spine and pelvis**, providing detailed cross-sectional images superior to plain radiographs.
- Since the **cervical exam was not performed**, cervical spine imaging is **mandatory** per ATLS (Advanced Trauma Life Support) protocols. High-energy falls carry significant risk of **cervical spine injury** even without obvious neurological symptoms.
- CT allows comprehensive assessment of **hip fractures, pelvic injuries, and the entire spine** (cervical, thoracic, lumbar), identifying both obvious and **subtle fractures** that may be missed on plain films.
- This approach provides the most **efficient and thorough evaluation** in the acute trauma setting, allowing for appropriate surgical planning and ruling out life-threatening spinal instability.
*AP and lateral radiographs of hips*
- Plain radiographs provide **limited detail** and may **miss subtle fractures**, particularly in complex areas like the pelvis and acetabulum.
- This option **fails to address cervical spine clearance**, which is essential in all high-energy trauma patients, especially when cervical exam has not been performed.
- Radiographs are insufficient for **comprehensive trauma evaluation** after a fall from height.
*Lateral radiograph (x-ray) of hips*
- A single lateral view is **grossly insufficient** for evaluating hip and pelvic fractures, providing only a **two-dimensional perspective** that can miss significant injuries.
- This option **completely neglects spinal evaluation**, which is dangerous in an uncleared trauma patient with a high-energy mechanism.
*Magnetic resonance imaging (MRI) of hips, knees, lumbar, and cervical area*
- While MRI excels at evaluating **soft tissues, ligaments, and bone marrow**, it is **not the initial imaging modality** for acute bony trauma due to longer scan times and lower sensitivity for acute fractures compared to CT.
- MRI is **time-consuming and impractical** in the emergency setting for initial fracture assessment, potentially delaying definitive treatment.
- CT is superior for evaluating **acute skeletal injuries** in the trauma bay.
*Anterior-posterior (AP) and lateral radiographs of hips, knees, lumbar, and cervical area*
- Multiple plain radiographs have **limited sensitivity** for complex or non-displaced fractures, particularly in the **spine and pelvis**, making them inadequate for high-energy trauma evaluation.
- Obtaining multiple radiographic views requires **numerous patient repositionings**, which risks further injury if **spinal instability** is present.
- Plain films provide significantly **less diagnostic information** than CT scanning for trauma assessment.
Pelvic radiologic landmarks US Medical PG Question 2: An 80-year-old woman is brought to the emergency department for left hip pain 30 minutes after she fell while walking around in her room. Examination shows left groin tenderness. The range of motion of the left hip is limited because of pain. An x-ray of the hip shows a linear fracture of the left femoral neck with slight posterior displacement of the femur. Which of the following arteries was most likely damaged in the patient's fall?
- A. Superior gluteal artery
- B. Deep circumflex iliac
- C. Deep femoral artery
- D. Obturator
- E. Medial circumflex femoral (Correct Answer)
Pelvic radiologic landmarks Explanation: ***Medial circumflex femoral***
- This artery is the **primary blood supply** to the femoral head and neck, making it highly vulnerable to injury in cases of femoral neck fractures.
- Damage to the medial circumflex femoral artery significantly increases the risk of **avascular necrosis** of the femoral head.
*Superior gluteal artery*
- The superior gluteal artery primarily supplies the **gluteus medius** and **minimus muscles**.
- It is **not directly involved** in the primary blood supply to the femoral head and neck.
*Deep circumflex iliac*
- This artery mainly supplies the **iliac fossa** and the **abdominal wall muscles**.
- It does not contribute significantly to the blood supply of the femoral neck.
*Deep femoral artery*
- The deep femoral artery, also known as the **profunda femoris artery**, is the main supply to the **thigh muscles**.
- While it gives rise to the circumflex arteries, it is not the artery directly compromised in a femoral neck fracture.
*Obturator*
- The obturator artery primarily supplies the **adductor muscles** of the thigh and contributes a small branch to the femoral head via the **ligamentum teres**.
- This contribution is **insufficient** to maintain viability of the femoral head, especially in trauma to the femoral neck.
Pelvic radiologic landmarks US Medical PG Question 3: A 69-year-old woman presents with pain in her hip and groin. She states that the pain is present in the morning, and by the end of the day it is nearly unbearable. Her past medical history is notable for a treated episode of acute renal failure, diabetes mellitus, obesity, and hypertension. Her current medications include losartan, metformin, insulin, and ibuprofen. The patient recently started taking high doses of vitamin D as she believes that it could help her symptoms. She also states that she recently fell off the treadmill while exercising at the gym. On physical exam you note an obese woman. There is pain, decreased range of motion, and crepitus on physical exam of her right hip. The patient points to the areas that cause her pain stating that it is mostly over the groin. The patient's skin turgor reveals tenting. Radiography is ordered.
Which of the following is most likely to be found on radiography?
- A. Loss of joint space and osteophytes (Correct Answer)
- B. Posterior displacement of the femoral head
- C. Hyperdense foci in the ureters
- D. Femoral neck fracture
- E. Normal radiography
Pelvic radiologic landmarks Explanation: ***Loss of joint space and osteophytes***
- The patient's presentation with **hip and groin pain worsened by activity**, improved with rest, and associated with **crepitus** and **decreased range of motion**, is highly suggestive of **osteoarthritis**.
- **Osteoarthritis** is characterized radiographically by **loss of joint space**, **osteophytes** (bone spurs), subchondral sclerosis, and subchondral cysts.
*Posterior displacement of the femoral head*
- This finding is characteristic of a **posterior hip dislocation**, which usually presents with severe pain and an inability to bear weight after a significant traumatic event.
- While the patient fell, her symptoms are chronic and progressive, and she has signs of arthritis rather than acute dislocation.
*Hyperdense foci in the ureters*
- These would indicate **kidney stones**, which typically present with acute, severe flank pain radiating to the groin, and hematuria.
- The patient's symptoms are chronic and localized to the hip joint, making kidney stones an unlikely cause of her primary complaint.
*Femoral neck fracture*
- A **femoral neck fracture** would cause acute, severe hip pain, inability to bear weight, and often external rotation and shortening of the leg, usually following a fall.
- Although she fell, her chronic, activity-related pain and crepitus are more indicative of a degenerative process.
*Normal radiography*
- Given the patient's age, chronic and worsening hip pain, physical exam findings of crepitus and decreased range of motion, and risk factors like obesity, it is highly improbable that her hip X-rays would be normal.
- These symptoms are classic for **osteoarthritis**, which shows distinct radiographic changes.
Pelvic radiologic landmarks US Medical PG Question 4: A 40-year-old woman comes to the physician because of a 2-week history of anal pain that occurs during defecation and lasts for several hours. She reports that she often strains during defecation and sees bright red blood on toilet paper after wiping. She typically has 3 bowel movements per week. Physical examination shows a longitudinal, perianal tear. This patient's symptoms are most likely caused by tissue injury in which of the following locations?
- A. Anterior midline of the anal canal, proximal to the pectinate line
- B. Posterior midline of the anal canal, distal to the pectinate line (Correct Answer)
- C. Posterior midline of the anal canal, proximal to the pectinate line
- D. Lateral aspect of the anal canal, distal to the pectinate line
- E. Anterior midline of the anal canal, distal to the pectinate line
Pelvic radiologic landmarks Explanation: ***Posterior midline of the anal canal, distal to the pectinate line***
- The described symptoms of severe **anal pain during and after defecation**, bright red blood on toilet paper, and straining with defecation are classic for an **anal fissure**.
- Anal fissures most commonly occur in the **posterior midline** of the anal canal, **distal to the pectinate (dentate) line**, due to reduced blood supply and increased mechanical stress in this area.
*Anterior midline of the anal canal, proximal to the pectinate line*
- Fissures can occur in the anterior midline but are less common than posterior midline fissures.
- Lesions proximal to the pectinate line are typically less painful as this area is innervated by the autonomic nervous system, unlike the highly sensitive somatic innervation distal to the pectinate line.
*Posterior midline of the anal canal, proximal to the pectinate line*
- While the posterior midline is a common location for fissures, involvement **proximal to the pectinate line** would likely present with less severe pain compared to the highly sensitive area distal to it.
- Lesions proximal to the pectinate line are more commonly internal hemorrhoids or proctitis, which present differently.
*Lateral aspect of the anal canal, distal to the pectinate line*
- Fissures in the lateral position are **atypical** and may suggest underlying conditions such as **Crohn's disease**, tuberculosis, or sexually transmitted infections, which are not indicated in this patient's presentation.
- The **midline** positions (anterior or posterior) are far more common for idiopathic anal fissures.
*Anterior midline of the anal canal, distal to the pectinate line*
- Though the anterior midline, distal to the pectinate line, is a possible location for fissures (especially in women), the **posterior midline** is the **most common** site due to anatomical factors.
- Given the classic presentation, the most frequent location is the most likely answer.
Pelvic radiologic landmarks US Medical PG Question 5: An MRI of a patient with low back pain reveals compression of the L5 nerve root. Which of the following muscles would most likely show weakness during physical examination?
- A. Tibialis posterior
- B. Tibialis anterior (Correct Answer)
- C. Gastrocnemius
- D. Quadriceps femoris
Pelvic radiologic landmarks Explanation: ***Tibialis anterior***
- The **L5 nerve root** primarily innervates muscles responsible for **dorsiflexion** of the foot, with the **tibialis anterior** being the primary dorsiflexor.
- Weakness of the tibialis anterior would manifest as difficulty lifting the front of the foot, potentially leading to a **foot drop** gait.
*Tibialis posterior*
- The **tibialis posterior** is primarily innervated by the **tibial nerve** (S1-S2) and is responsible for **plantarflexion** and **inversion** of the foot.
- Weakness in this muscle would not be the most likely presentation of L5 nerve root compression.
*Gastrocnemius*
- The **gastrocnemius** muscle is primarily innervated by the **tibial nerve** (S1-S2) and is a powerful **plantarflexor** of the foot.
- Weakness in this muscle would indicate an S1 or S2 nerve root issue, not typically L5.
*Quadriceps femoris*
- The **quadriceps femoris** is innervated by the **femoral nerve**, predominantly originating from the **L2, L3, and L4 nerve roots**.
- Weakness would manifest as difficulty extending the knee, which is not characteristic of L5 compression.
Pelvic radiologic landmarks US Medical PG Question 6: A 45-year-old man is brought to the emergency department following a motor vehicle collision. He reports right hip pain and numbness along the right thigh. Physical examination shows decreased sensation to light touch over a small area of the proximal medial thigh. X-rays of the pelvis show a displaced pelvic ring fracture. Further evaluation of this patient is most likely to show which of the following findings?
- A. Sensory deficit of the dorsal foot
- B. Absent cremasteric reflex
- C. Impaired hip extension
- D. Impaired adduction of the hip (Correct Answer)
- E. Impaired extension of the knee
Pelvic radiologic landmarks Explanation: ***Impaired adduction of the hip***
- The patient's **numbness along the right thigh** and **decreased sensation to light touch over the proximal medial thigh**, combined with a **pelvic ring fracture**, points to probable injury of the **obturator nerve**.
- The **obturator nerve** innervates the **adductor muscles** of the hip, and its injury would result in impaired hip adduction and sensory deficits in the medial thigh.
*Sensory deficit of the dorsal foot*
- A sensory deficit on the **dorsal foot** is typically associated with injury to the **peroneal nerve**, which is less likely to be affected by a pelvic ring fracture leading to medial thigh numbness.
- Peroneal nerve injury often results from trauma to the **lateral knee** or prolonged compression.
*Absent cremasteric reflex*
- An absent **cremasteric reflex** suggests injury to the **ilioinguinal** or **genitofemoral nerves**, or spinal cord injury at the L1-L2 level.
- While these nerves can be affected by pelvic trauma, the specific sensory deficit described (proximal medial thigh) aligns more with obturator nerve involvement.
*Impaired hip extension*
- **Hip extension** is primarily controlled by the **gluteus maximus** and **hamstrings**, which are innervated by the **inferior gluteal nerve** and **sciatic nerve**, respectively.
- Injury to these nerves or muscles would not typically cause numbness in the proximal medial thigh.
*Impaired extension of the knee*
- **Knee extension** is mediated by the **quadriceps femoris** muscle group, innervated by the **femoral nerve**.
- While the femoral nerve can be injured in severe pelvic trauma, the sensory distribution described does not match the typical sensory deficits of femoral nerve injury (anterior and medial thigh, medial leg).
Pelvic radiologic landmarks US Medical PG Question 7: A 40-year-old woman is brought to the emergency department by a paramedic team from the scene of a motor vehicle accident where she was the driver. The patient was restrained by a seat belt and was unconscious at the scene. On physical examination, the patient appears to have multiple injuries involving the trunk and extremities. There are no penetrating injuries to the chest. As part of her trauma workup, a CT scan of the chest is ordered. At what vertebral level of the thorax is this image from?
- A. T1
- B. T6
- C. T4
- D. T5
- E. T8 (Correct Answer)
Pelvic radiologic landmarks Explanation: ***T8***
- The CT image shows the **inferior vena cava (IVC)** located anterior and to the right of the aorta, and the **esophagus** located posterior to the aorta and slightly to the left. The **azygos vein** is seen to the right of the vertebral body and posterior to the esophagus.
- The **mainstem bronchi** are no longer visible, indicating a level below the carina. The presence of the IVC, aorta, esophagus, and azygos vein with the absence of mainstem bronchi is characteristic of the **T8 vertebral level**.
*T1*
- At the T1 level, the structures would primarily be the **trachea** anterior to the esophagus, with the main great vessels (e.g., brachiocephalic veins and arteries) visible, not the IVC.
- The mainstem bronchi would not yet be visualized at this higher level.
*T6*
- At the T6 level, the **trachea would have already bifurcated into the mainstem bronchi**, which would be prominent structures visible on the CT scan.
- While the aorta and esophagus would be present, the specific arrangement relative to the mainstem bronchi would differentiate it from T8.
*T4*
- The T4 level is typically associated with the **carina**, where the trachea bifurcates into the mainstem bronchi.
- The great vessels would be prominent, but the IVC in its more inferior course would not be as distinctly visualized in this configuration compared to T8.
*T5*
- At the T5 level, the **mainstem bronchi** would still be clearly visible, having just diverged from the trachea.
- While vessels like the aorta are present, the key differentiating factor from T8 is the presence of the mainstem bronchi.
Pelvic radiologic landmarks US Medical PG Question 8: A 35-year-old man comes to the physician because of a 3-month history of intermittent right lateral hip pain that radiates to the thigh. Climbing stairs and lying on his right side aggravates the pain. Examination shows tenderness to palpation over the upper lateral part of the right thigh. There is no swelling. When the patient is asked to abduct the right leg against resistance, tenderness is noted. An x-ray of the pelvis shows no abnormalities. Which of the following structures is the most likely source of this patient's pain?
- A. Femoral head
- B. Greater trochanter (Correct Answer)
- C. Iliotibial band
- D. Acetabulum
- E. Lateral femoral cutaneous nerve
Pelvic radiologic landmarks Explanation: ***Greater trochanter***
- The patient's symptoms of **intermittent right lateral hip pain** radiating to the thigh, aggravated by climbing stairs and lying on the affected side, and tenderness over the **upper lateral part of the right thigh** are classic signs of **trochanteric bursitis**.
- Pain with **resisted abduction** further points to inflammation of the **gluteus medius** or its associated bursa at the greater trochanter.
*Femoral head*
- Pain originating from the **femoral head** typically presents as deep, generalized groin or hip joint pain, often exacerbated by weight-bearing activities, and may be associated with limited range of motion in multiple planes.
- An **x-ray showing no abnormalities** makes femoral head issues like avascular necrosis or significant arthritis less likely.
*Iliotibial band*
- **Iliotibial band (ITB) syndrome** usually causes pain along the **lateral aspect of the knee**, particularly in runners or cyclists, due to friction over the lateral femoral epicondyle.
- While the ITB traverses the lateral thigh, the primary point of tenderness and mechanism of pain in this case (tenderness over the upper lateral thigh, pain with resisted abduction) is not typical for ITB syndrome affecting the knee.
*Acetabulum*
- Pain from the **acetabulum** would generally be deep within the hip joint, similar to femoral head issues, and often accompanied by a **limited range of motion** or clicking/locking sensations, and would be associated with intra-articular pathology.
- An **unremarkable X-ray** and the specific finding of **tenderness over the lateral thigh** make acetabular pathology less likely.
*Lateral femoral cutaneous nerve*
- Entrapment of the **lateral femoral cutaneous nerve** (meralgia paresthetica) typically causes **numbness, burning, or tingling** on the anterolateral thigh, not primarily sharp, intermittent pain aggravated by movement and palpation in the manner described.
- While pain can be present, the absence of **paresthesias** and the mechanical nature of the pain (aggravated by resisted abduction) make nerve entrapment less probable.
Pelvic radiologic landmarks US Medical PG Question 9: A 25-year-old man presents with progressive weakness and urinary retention. MRI of the spine shows an intramedullary lesion from T10-T12 with expansion of the spinal cord and syrinx formation. The conus medullaris is identified at the L1-L2 level (normal: L1-L2). The filum terminale appears thickened at 3 mm. CSF flow study shows obstruction at the lesion site. Evaluate these radiologic landmarks and their relationships to determine the neurological level most likely affected.
- A. Cauda equina only, sparing upper motor neurons
- B. Conus medullaris with mixed upper and lower motor neuron signs
- C. Thoracic cord with pure upper motor neuron signs below T10
- D. Epiconus (T12-L1) with distal lower extremity and sphincter dysfunction (Correct Answer)
- E. Lower thoracic nerve roots with radicular pain pattern only
Pelvic radiologic landmarks Explanation: ***Epiconus (T12-L1) with distal lower extremity and sphincter dysfunction***
- The **epiconus** encompasses spinal segments **L4-S2**, which anatomically correspond to the vertebral levels **T12-L1**; a lesion here characteristically causes **bladder/bowel dysfunction** and weakness.
- This location accounts for the **urinary retention** and progressive weakness while sparing the higher thoracic functions, fitting the intramedullary expansion seen at the lower thoracic-lumbar transition.
*Cauda equina only, sparing upper motor neurons*
- A **cauda equina** lesion involves the **nerve roots** below the level of the conus (L2) and presents with **purely lower motor neuron (LMN)** signs.
- The intramedullary nature of the lesion at **T10-T12** indicates involvement of the spinal cord itself, which would typically involve **upper motor neuron (UMN)** features or a mixed picture.
*Conus medullaris with mixed upper and lower motor neuron signs*
- The **conus medullaris** corresponds to segments **S3-Co1** and is located at the vertebral level of **L1-L2**, which is distal to the primary lesion core reported at T10.
- Conus lesions typically present with **early autonomic dysfunction** and symmetric saddle anesthesia, but the lesion described extends higher into the **epiconus** region.
*Thoracic cord with pure upper motor neuron signs below T10*
- A lesion at the **mid-thoracic cord** (T10-T12) would primarily produce **spasticity** and hyperreflexia typical of **UMN syndrome** in the lower extremities.
- However, because this specific region houses the lower lumbar and upper sacral segments (the **epiconus**), it frequently yields a complex focal clinical picture involving specific root-level deficits.
*Lower thoracic nerve roots with radicular pain pattern only*
- **Radicular pain** results from compression of exiting **nerve roots**, whereas an **intramedullary lesion** like the one described involves the central cord parenchyma.
- The presence of **urinary retention** and a **syrinx** indicates deep spinal cord involvement and syrinx-related neurological deficits, not mere peripheral root irritation.
Pelvic radiologic landmarks US Medical PG Question 10: A 58-year-old woman with breast cancer undergoes staging CT. The scan shows a solitary 2 cm lesion in the liver at the junction of segments IVa, V, and VIII, directly adjacent to the middle hepatic vein. PET scan shows FDG avidity. The oncologist requests evaluation for surgical resection. The radiologist notes the lesion's relationship to the portal vein bifurcation (Cantlie's line). Evaluate the radiologic anatomical landmarks to determine resectability and surgical approach.
- A. Unresectable due to middle hepatic vein involvement; systemic therapy only
- B. Central hepatectomy with middle hepatic vein reconstruction (Correct Answer)
- C. Right hepatectomy with adequate future liver remnant assessment
- D. Extended right hepatectomy including segment IV
- E. Radiofrequency ablation given central location
Pelvic radiologic landmarks Explanation: ***Central hepatectomy with middle hepatic vein reconstruction***
- A lesion involving segments **IVa, V, and VIII** is centrally located; a **central hepatectomy** (or mesohepatectomy) allows for the preservation of the **peripheral right and left segments**, maintaining a larger **future liver remnant (FLR)**.
- Involvement of the **middle hepatic vein** requires skilled surgical planning, including possible **vascular reconstruction** or ensuring adequate **venous drainage** of the remaining segments to avoid congestion.
*Unresectable due to middle hepatic vein involvement; systemic therapy only*
- Engagement with a major hepatic vein does not automatically render a lesion **unresectable** in modern hepatobiliary surgery if the other hepatic veins and **portal inflow** are intact.
- Radical resection can still be achieved through **advanced surgical techniques** or by performing an **extended hepatectomy** if the patient's liver function permits.
*Right hepatectomy with adequate future liver remnant assessment*
- A standard **right hepatectomy** removes segments V through VIII, but since this lesion involves segment **IVa** (part of the left hemiliver), a standard right procedure might leave a **positive medial margin**.
- Although assessment of the **FLR** is critical, a standard right hepatectomy alone does not address the involvement of the **middle hepatic vein** and segment IVa effectively.
*Extended right hepatectomy including segment IV*
- An **extended right hepatectomy** (right trisectionectomy) would involve removing segments IV through VIII, which provides a high chance of **R0 resection** for a central lesion.
- However, this is a much more morbid procedure than a **central hepatectomy** and may not be necessary if the patient has a limited **liver reserve** or if the disease is localized.
*Radiofrequency ablation given central location*
- **Radiofrequency ablation (RFA)** is generally contraindicated for 2 cm lesions directly adjacent to major vessels like the **middle hepatic vein** due to the **heat-sink effect**.
- The blood flow in the large vein dissipates the thermal energy, leading to incomplete treatment and a high risk of **local recurrence** compared to surgical resection.
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