X-ray principles and interpretation US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for X-ray principles and interpretation. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
X-ray principles and interpretation US Medical PG Question 1: A 57-year-old man presents to his family physician for a routine exam. He feels well and reports no new complaints since his visit last year. Last year, he had a colonoscopy which showed no polyps, a low dose chest computerized tomography (CT) scan that showed no masses, and routine labs which showed a fasting glucose of 93 mg/dL. He is relatively sedentary and has a body mass index (BMI) of 24 kg/m^2. He has a history of using methamphetamines, alcohol (4-5 drinks per day since age 30), and tobacco (1 pack per day since age 18), but he joined Alcoholics Anonymous and has been in recovery, not using any of these for the past 7 years. Which of the following is indicated at this time?
- A. Colonoscopy
- B. Chest computerized tomography (CT) scan (Correct Answer)
- C. Abdominal ultrasound
- D. Chest radiograph
- E. Fasting glucose
X-ray principles and interpretation Explanation: ***Chest computerized tomography (CT) scan***
- This patient has a significant **smoking history** (1 pack per day since age 18 = **39 pack-years**) and is 57 years old, placing him in a high-risk group for **lung cancer**.
- Annual low-dose CT screening for lung cancer is recommended for individuals aged 50-80 with a 20 pack-year smoking history who currently smoke or have quit within the past 15 years.
- He meets all criteria: age 57, 39 pack-years, and quit only 7 years ago (within the 15-year window).
- Since he had screening **last year** with no masses, this year's visit represents the appropriate time for his **annual follow-up screening**.
*Colonoscopy*
- The patient had a colonoscopy last year with **no polyps**, suggesting he is at average risk for colorectal cancer.
- For individuals at average risk with normal findings, repeat screening colonoscopy is typically recommended every **10 years** (or every 5 years for flexible sigmoidoscopy), not annually.
*Abdominal ultrasound*
- One-time abdominal ultrasound screening for **abdominal aortic aneurysm (AAA)** is recommended for men aged 65-75 who have ever smoked.
- This patient is only 57 years old and does not yet meet the age criteria for AAA screening.
*Chest radiograph*
- While a chest radiograph can identify some lung abnormalities, a **low-dose CT scan** is far more sensitive and specific for detecting early-stage lung cancer in high-risk populations.
- Chest radiography is **not recommended** as a screening tool for lung cancer due to its lower sensitivity and lack of mortality benefit in trials.
*Fasting glucose*
- The patient had a **normal fasting glucose** of 93 mg/dL last year, and there are no new symptoms suggestive of diabetes.
- For asymptomatic adults with normal glucose, diabetes screening is typically repeated every **3 years**.
- Annual re-screening is not indicated without new risk factors or symptoms.
X-ray principles and interpretation US Medical PG Question 2: 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)
X-ray principles and interpretation 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.
X-ray principles and interpretation US Medical PG Question 3: A tall, slender 32-year-old man comes to the emergency room because of sudden chest pain, cough, and shortness of breath. On physical examination, he has decreased breath sounds on the right. Chest radiography shows translucency on the right side of his chest. His pCO2 is elevated and pO2 is decreased. What is the most likely cause of his symptoms?
- A. Spontaneous pneumothorax (Correct Answer)
- B. Chronic obstructive pulmonary disease
- C. Tension pneumothorax
- D. Asthma
- E. Pneumonia
X-ray principles and interpretation Explanation: ***Spontaneous pneumothorax***
- The patient's presentation with **sudden chest pain**, **cough**, and **shortness of breath** in a **tall, slender young man** is classic for a primary spontaneous pneumothorax.
- **Decreased breath sounds** on the affected side and **translucency on chest X-ray** (indicating air in the pleural space) further support this diagnosis.
*Chronic obstructive pulmonary disease*
- COPD typically affects older individuals with a history of smoking and presents with **chronic progressive dyspnea**, not sudden onset.
- While COPD can lead to secondary spontaneous pneumothorax, the patient's age and lack of pre-existing lung disease make this less likely as the primary cause.
*Tension pneumothorax*
- A tension pneumothorax is a **life-threatening condition causing mediastinal shift** and severe hemodynamic compromise (e.g., hypotension, tracheal deviation) which are not described.
- While it shares some features, the absence of these critical signs means a simple spontaneous pneumothorax is more likely first.
*Asthma*
- Asthma presents with **episodic wheezing**, cough, and shortness of breath, often triggered by allergens or exercise.
- The sudden onset of symptoms with **decreased localized breath sounds** and radiological findings of transparencies do not align with typical asthma exacerbations.
*Pneumonia*
- Pneumonia usually involves **fever, productive cough, and localized crackles** or bronchial breath sounds on examination.
- Chest X-rays in pneumonia show **infiltrates or consolidation**, which contrast with the translucency seen in this case.
X-ray principles and interpretation US Medical PG Question 4: A 64-year-old man presents to the office for an annual physical examination. He has no complaints at this visit. His chart states that he has a history of hypertension, chronic obstructive pulmonary disease (emphysema), Raynaud’s disease, and glaucoma. He is a 30 pack-year smoker. His medications included lisinopril, tiotropium, albuterol, nifedipine, and latanoprost. The blood pressure is 139/96 mm Hg, the pulse is 86/min, the respiration rate is 16/min, and the temperature is 37.2°C (99.1°F). On physical examination, his pupils are equal, round, and reactive to light. The cardiac auscultation reveals an S4 gallop without murmur, and the lungs are clear to auscultation bilaterally. However, the inspection of the chest wall shows an enlarged anterior to posterior diameter. Which of the following is the most appropriate screening test for this patient?
- A. Low-dose CT (Correct Answer)
- B. Bronchoalveolar lavage with cytology
- C. Magnetic resonance imaging
- D. Pulmonary function tests
- E. Chest radiograph
X-ray principles and interpretation Explanation: ***Low-dose CT***
- This patient, a 64-year-old with a 30 pack-year smoking history and current emphysema (COPD), falls precisely within the **high-risk criteria** for lung cancer screening.
- The **USPSTF guidelines** recommend annual **low-dose computed tomography (LDCT)** for individuals aged 50-80 years with a 20 pack-year smoking history who currently smoke or have quit within the past 15 years.
*Bronchoalveolar lavage with cytology*
- This is an **invasive diagnostic procedure** used to collect cells and fluid directly from the airways, typically performed when there is already suspicion of a lung malignancy or infection.
- It is not a recommended **screening test** for asymptomatic individuals due to its invasiveness and the absence of clear evidence of benefit as a primary screening tool.
*Magnetic resonance imaging*
- **MRI** is primarily used for evaluating soft tissue structures, defining tumor extent, and assessing metastatic disease, but it is **not the preferred imaging modality for lung cancer screening** due to its lower spatial resolution for pulmonary nodules compared to CT and higher cost.
- It involves longer scan times and is not routinely used for primary lung screening.
*Pulmonary function tests*
- **PFTs** are used to assess lung function, diagnose and monitor respiratory conditions like COPD, and evaluate the severity of airflow obstruction.
- While important for managing his **emphysema**, PFTs do not directly screen for **lung cancer**; they measure how well the lungs work.
*Chest radiograph*
- A **chest X-ray** is less sensitive than LDCT for detecting small lung nodules and early-stage lung cancer due to its two-dimensional nature and potential for superimposition of structures.
- While readily available and less expensive, it is **not recommended for lung cancer screening** as it has not shown a mortality benefit in randomized controlled trials compared to no screening.
X-ray principles and interpretation US Medical PG Question 5: During an evaluation of a new diagnostic imaging modality for detecting salivary gland tumors, 90 patients tested positive out of the 100 patients who tested positive with the gold standard test. A total of 80 individuals tested negative with the new test out of the 100 individuals who tested negative with the gold standard test. What is the positive likelihood ratio for this test?
- A. 80/90
- B. 90/100
- C. 90/20 (Correct Answer)
- D. 90/110
- E. 10/80
X-ray principles and interpretation Explanation: ***90/20***
- The **positive likelihood ratio (LR+)** is calculated as **sensitivity / (1 - specificity)**. To calculate this, we first need to determine the values for true positives (TP), false positives (FP), true negatives (TN), and false negatives (FN).
- Given that 90 out of 100 actual positive patients tested positive, **TP = 90** and **FN = 100 - 90 = 10**. Also, 80 out of 100 actual negative patients tested negative, so **TN = 80** and **FP = 100 - 80 = 20**.
- **Sensitivity** is the true positive rate (TP / (TP + FN)) = 90 / (90 + 10) = 90 / 100.
- **Specificity** is the true negative rate (TN / (TN + FP)) = 80 / (80 + 20) = 80 / 100.
- Therefore, LR+ = (90/100) / (1 - 80/100) = (90/100) / (20/100) = **90/20**.
*80/90*
- This option incorrectly represents the components for the likelihood ratio. It seems to misinterpret the **true negative** count and the **true positive** count.
- It does not follow the formula for LR+ which is **sensitivity / (1 - specificity)**.
*90/100*
- This value represents the **sensitivity** of the test, which is the proportion of true positives among all actual positives.
- It does not incorporate the **false positive rate** (1 - specificity) in the denominator required for the positive likelihood ratio.
*90/110*
- This option incorrectly combines different values, possibly by confusing the denominator for sensitivity or specificity calculations.
- It does not correspond to the formula for the **positive likelihood ratio**.
*10/80*
- This value seems to relate to the inverse of the **false negative rate** (10/100) or misrepresents the relationship between false negatives and true negatives.
- It is not correctly structured to represent the **positive likelihood ratio (LR+)**.
X-ray principles and interpretation US Medical PG Question 6: A 6-month-old boy is brought to the emergency department by his mother, who informs the doctor that her alcoholic husband hit the boy hard on his back. The blow was followed by excessive crying for several minutes and the development of redness in the area. On physical examination, the boy is dehydrated, dirty, and irritable and when the vital signs are checked, they reveal tachycardia. He cries immediately upon the physician touching the area around his left scapula. The doctor strongly suspects a fracture of the 6th, 7th, or 8th retroscapular posterior ribs. Evaluation of his skeletal survey is normal. The clinician is concerned about child abuse in this case. Which of the following is the most preferred imaging technique as the next step in the diagnostic evaluation of the infant?
- A. Bedside ultrasonography
- B. Magnetic resonance imaging
- C. Babygram
- D. Chest computed tomography scan
- E. Skeletal survey in 2 weeks (Correct Answer)
X-ray principles and interpretation Explanation: ***Skeletal survey in 2 weeks***
- A repeat **skeletal survey in 2 weeks** is the most appropriate next step in suspected child abuse cases with an initial normal survey, as it allows for the detection of **healing fractures** that may not be apparent immediately after injury.
- New bone formation and callus development around a fracture site become radiographically visible after approximately 7 to 14 days, improving the detection rate of subtle or undisplaced fractures.
*Bedside ultrasonography*
- While **ultrasonography** can detect acute fractures, especially in cartilage and non-ossified bones, its utility in a comprehensive assessment for multiple non-displaced rib fractures as part of a child abuse workup is limited.
- It is highly **operator-dependent** and may not provide the full skeletal overview required in suspected child abuse.
*Magnetic resonance imaging*
- **MRI** is excellent for evaluating soft tissue injuries, bone marrow edema, and non-ossified cartilaginous structures. However, it is not the primary imaging modality for detecting acute or subacute fractures of ossified bone and requires **sedation** in infants, making it less practical for routine skeletal screening.
- The **high cost** and limited availability of MRI also make it less suitable as a first-line diagnostic tool for rib fractures in this context.
*Babygram*
- A **babygram** is a single large radiograph of an infant's entire body, often used to rapidly assess for gross developmental anomalies or immediate concerns.
- It provides **less detailed imaging** of individual bones compared to a standard skeletal survey and is insufficient for reliably detecting subtle or non-displaced rib fractures.
*Chest computed tomography scan*
- A **chest CT scan** is highly sensitive for detecting acute rib fractures, even subtle ones. However, it exposes the infant to **significant radiation** and is usually reserved for specific clinical indications, such as suspected internal organ injury, rather than as a primary screening tool for rib fractures in child abuse in an otherwise stable patient.
- It does not provide a comprehensive view of the entire skeleton, which is crucial for identifying other potential abuse-related injuries elsewhere.
X-ray principles and interpretation US Medical PG Question 7: A 2-year-old child is brought to the emergency department with rapid breathing and a severe cyanotic appearance of his lips, fingers, and toes. He is known to have occasional episodes of mild cyanosis, especially when he is extremely agitated. This is the worst episode of this child’s life, according to his parents. He was born with an APGAR score of 8 via a normal vaginal delivery. His development is considered delayed compared to children of his age. History is significant for frequent squatting after strenuous activity. On auscultation, there is evidence of a systolic ejection murmur at the left sternal border. On examination, his oxygen saturation is 71%, blood pressure is 81/64 mm Hg, respirations are 42/min, pulse is 129/min, and temperature is 36.7°C (98.0°F). Which of the following will most likely be seen on chest x-ray (CXR)?
- A. Egg on a string
- B. Boot-shaped heart (Correct Answer)
- C. Increased pulmonary vascular markings
- D. Cardiomegaly with globular heart
- E. Figure-3 sign
X-ray principles and interpretation Explanation: ***Boot-shaped heart***
- The patient's presentation with **cyanosis**, **squatting spells**, and a **systolic ejection murmur** is classic for **Tetralogy of Fallot** (TOF).
- A **boot-shaped heart** (Coeur en sabot) on chest X-ray is a characteristic finding in TOF, caused by **right ventricular hypertrophy** and an upturned cardiac apex, leading to a concave pulmonary artery segment.
*Egg on a string*
- This CXR finding is characteristic of **Transposition of the Great Arteries (TGA)**, where the aorta and pulmonary artery are switched, creating an "egg" outline with a narrow vascular pedicle ("string").
- TGA typically presents with severe **cyanosis** from birth and does not usually involve squatting spells or a loud systolic murmur from a prominent **right ventricular outflow tract obstruction**.
*Increased pulmonary vascular markings*
- This finding is common in conditions with **left-to-right shunting** or **increased pulmonary blood flow**, such as a **ventricular septal defect (VSD)** or **patent ductus arteriosus (PDA)**.
- In Tetralogy of Fallot, there is typically **decreased pulmonary blood flow** due to **pulmonic stenosis**, leading to *decreased* pulmonary vascular markings.
*Cardiomegaly with globular heart*
- A **globular heart** is a non-specific finding often associated with **pericardial effusion** or **dilated cardiomyopathy**, where the heart appears enlarged and rounded.
- While TOF can cause cardiomegaly (specifically **right ventricular hypertrophy**), the characteristic shape is "boot-shaped," not globally enlarged or globular.
*Figure-3 sign*
- The **figure-3 sign** on CXR is pathognomonic for **aortic coarctation**, caused by indentation of the aorta at the coarctation site and post-stenotic dilation.
- This condition presents with signs of **heart failure**, **differential cyanosis** (if preductal), and **blood pressure discrepancies** between upper and lower extremities, not the cyanotic spells and squatting seen in this case.
X-ray principles and interpretation US Medical PG Question 8: A 27-year-old man presents to the emergency department with back pain. The patient states that he has back pain that has been steadily worsening over the past month. He states that his pain is worse in the morning but feels better after he finishes at work for the day. He rates his current pain as a 7/10 and says that he feels short of breath. His temperature is 99.5°F (37.5°C), blood pressure is 130/85 mmHg, pulse is 80/min, respirations are 14/min, and oxygen saturation is 99% on room air. On physical exam, you note a young man who does not appear to be in any distress. Cardiac exam is within normal limits. Pulmonary exam is notable only for a minor decrease in air movement bilaterally at the lung bases. Musculoskeletal exam reveals a decrease in mobility of the back in all four directions. Which of the following is the best initial step in management of this patient?
- A. MRI of the sacroiliac joint (Correct Answer)
- B. CT scan of the chest
- C. Pulmonary function tests
- D. Ultrasound
- E. Radiography of the lumbosacral spine
X-ray principles and interpretation Explanation: ***MRI of the sacroiliac joint***
- The patient's symptoms of **worsening back pain**, morning stiffness that improves with activity, and decreased back mobility are highly suggestive of **ankylosing spondylitis**.
- **MRI** is the most sensitive imaging modality for detecting early inflammatory changes in the **sacroiliac joints** and spine, which are characteristic of ankylosing spondylitis, even before radiographic changes are visible.
*CT scan of the chest*
- While the patient reports feeling **short of breath**, his vital signs and oxygen saturation are normal, and he does not appear in acute distress.
- A CT scan of the chest would be a more appropriate step if there were clearer signs of acute pulmonary pathology, such as significant hypoxemia, fever, or adventitious lung sounds, which are not present here.
*Pulmonary function tests*
- **Shortness of breath** could eventually be a complication of severe ankylosing spondylitis due to restricted chest wall expansion.
- However, PFTs are generally not the *initial* diagnostic step given the primary presentation of back pain and the need to confirm the underlying rheumatologic condition first.
*Ultrasound*
- **Ultrasound** is not a primary imaging modality for evaluating the sacroiliac joints or the spine in the context of suspected ankylosing spondylitis.
- It could be useful for assessing peripheral joint inflammation in other arthropathies, but not for axial involvement.
*Radiography of the lumbosacral spine*
- **X-rays of the lumbosacral spine** might show changes in advanced ankylosing spondylitis (e.g., squaring of vertebrae, syndesmophytes), but they are often normal in the early stages of the disease.
- **MRI** is superior for detecting early inflammatory changes and is often used to diagnose the condition before radiographic damage is evident.
X-ray principles and interpretation US Medical PG Question 9: A 74-year-old male is brought to the emergency department 1 hour after he fell from the top of the staircase at home. He reports pain in his neck as well as weakness of his upper extremities. He is alert and immobilized in a cervical collar. He has hypertension treated with hydrochlorothiazide. His pulse is 90/min and regular, respirations are 18/min, and blood pressure is 140/70 mmHg. Examination shows bruising and midline cervical tenderness. Neurologic examination shows diminished strength and sensation to pain and temperature in the upper extremities, particularly in the hands. Upper extremity deep tendon reflexes are absent. Strength, sensation, and reflexes in the lower extremities are intact. Anal sensation and tone are present. Babinski's sign is absent bilaterally. Which of the following is most likely to confirm the cause of this patient's neurologic examination findings?
- A. CT angiography of the neck
- B. MRI of the cervical spine without contrast (Correct Answer)
- C. X-ray of the cervical spine
- D. CT of the cervical spine with contrast
- E. Cervical myelography
X-ray principles and interpretation Explanation: ***MRI of the cervical spine without contrast***
- This patient presents with symptoms consistent with **central cord syndrome**, characterized by greater weakness in the upper extremities than the lower extremities, often following a hyperextension injury in older adults with pre-existing cervical spondylosis. **MRI is the gold standard for visualizing soft tissue injuries**, including spinal cord compression, edema, or hemorrhage, which are typical causes of central cord syndrome.
- Given the primary concern for spinal cord injury and the detailed neurological deficits indicating specific cord involvement, **MRI** offers the best resolution for evaluating the extent of cord damage, disc herniation, ligamentous injury, and pre-existing degenerative changes.
*CT angiography of the neck*
- **CT angiography** primarily evaluates the **vascular structures** of the neck (e.g., carotid and vertebral arteries) for dissection, stenosis, or occlusion.
- While vascular injury could occur in trauma, the patient's neurological findings (disproportionate upper extremity weakness, pain and temperature sensation loss) point more directly to **spinal cord pathology** rather than isolated vascular compromise as the primary cause.
*X-ray of the cervical spine*
- **X-rays** are useful for initial screening of **bony fractures** and significant dislocations but offer limited information about soft tissues, such as the spinal cord, ligaments, or intervertebral discs.
- They cannot adequately visualize the spinal cord damage responsible for the patient's specific neurological deficits, making it insufficient for confirming the cause of central cord syndrome.
*CT of the cervical spine with contrast*
- **CT scans** excel at visualizing **bony structures** and acute fractures, but even with contrast, they provide less detail of the **spinal cord parenchyma** and soft tissue ligaments compared to MRI.
- **Contrast** is typically used to highlight vascular structures, inflammatory processes, or tumors, which are not the primary diagnostic concerns suggested by this patient's acute post-traumatic presentation of central cord syndrome.
*Cervical myelography*
- **Myelography** involves injecting contrast into the subarachnoid space, followed by X-ray or CT imaging, to outline the spinal cord and nerve roots.
- While it can identify **spinal cord compression**, it is an **invasive procedure** with risks (e.g., headache, seizures) and has largely been replaced by the non-invasive and superior soft tissue imaging capabilities of MRI, especially in acute trauma.
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