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OMSB Diagnostic Radiology (OEDR) study materials
OMSB Diagnostic Radiology (OEDR) study resources

OMSB Diagnostic Radiology (OEDR) practice questions

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Question 1Physics, Instrumentation and Radiation Safety

Which radiation quantity is defined as the absorbed dose multiplied by a radiation weighting factor and is expressed in sieverts?

  1. Kerma
  2. Absorbed dose
  3. Exposure
  4. Equivalent dose Correct answer.

Explanation

Equivalent dose applies radiation weighting factors (wR) to absorbed dose to account for differing biological effectiveness of radiation types, and its SI unit is the sievert. Absorbed dose alone is measured in gray, while exposure and kerma are air-based quantities without biological weighting.

Question 2Physics, Instrumentation and Radiation Safety

Which interaction predominates when a diagnostic X-ray beam passes through soft tissue at typical energies of 30 to 60 keV?

  1. Pair production
  2. Photoelectric absorption Correct answer.
  3. Coherent scatter
  4. Compton scatter

Explanation

In soft tissue at diagnostic energies below roughly 60 keV, the photoelectric effect dominates because its probability varies strongly with atomic number and inversely with the cube of photon energy. This produces the high subject contrast seen in mammography and general radiography.

Question 3Physics, Instrumentation and Radiation Safety

A radiograph is produced using a 12:1 focused grid. What is the primary purpose of this device?

  1. To harden the beam spectrum
  2. To remove scattered radiation before it reaches the detector Correct answer.
  3. To increase the field of view
  4. To reduce patient skin dose

Explanation

A grid consists of radiopaque strips that absorb photons not traveling along the primary beam direction, thereby reducing scatter and improving image contrast. Grids do not reduce patient dose; they typically require higher exposure to compensate for grid attenuation.

Question 4Physics, Instrumentation and Radiation Safety

Which detector material is most commonly used in computed radiography plates?

  1. Cesium iodide
  2. Gadolinium oxysulfide
  3. Amorphous selenium
  4. Photostimulable barium fluorobromide Correct answer.

Explanation

Computed radiography uses a photostimulable phosphor plate, typically barium fluorobromide doped with europium, which stores a latent image that is read out by a laser. Amorphous selenium and cesium iodide are used in direct and indirect digital radiography respectively.

Question 5Physics, Instrumentation and Radiation Safety

During fluoroscopy, which feature most directly limits the maximum skin dose rate delivered to the patient?

  1. Last image hold
  2. Pulsed fluoroscopy
  3. Automatic exposure rate control Correct answer.
  4. Spectral beam filtration

Explanation

Automatic exposure rate control adjusts kVp and mA to maintain a target image brightness, and the system is configured so that the entrance skin air kerma rate does not exceed regulatory limits. Pulsed fluoroscopy and last image hold reduce total dose but do not by themselves cap the instantaneous rate.

Question 6Physics, Instrumentation and Radiation Safety

Which of the following best describes the ALARA principle in radiology practice?

  1. Every examination requires written consent
  2. Doses must never exceed the diagnostic reference level
  3. Occupational dose limits apply to all patients
  4. All exposures must be kept as low as reasonably achievable Correct answer.

Explanation

ALARA requires that radiation exposures be kept as low as reasonably achievable, taking economic and social factors into account, while still obtaining the required diagnostic information. Diagnostic reference levels are benchmarks for optimization, not absolute limits.

Question 7Physics, Instrumentation and Radiation Safety

A technologist increases the source-to-image distance from 100 cm to 150 cm while keeping the detector field size constant. How must the mAs be changed to maintain the same detector dose?

  1. Multiply by 1.25
  2. Multiply by 1.5
  3. Divide by 2.25
  4. Multiply by 2.25 Correct answer.

Explanation

Detector dose falls with the square of distance, so the inverse square law requires mAs to increase by the square of the distance ratio. The ratio is 150/100 = 1.5, and 1.5 squared equals 2.25, so mAs must be multiplied by 2.25.

Question 8Physics, Instrumentation and Radiation Safety

A radiograph of the lumbar spine is judged too light because the exposure index is below the manufacturer's target range. Which action best preserves image quality while correcting the problem?

  1. Increase the mAs and repeat the exposure Correct answer.
  2. Change the window and level display only
  3. Increase the kVp without changing mAs
  4. Widen the collimation field

Explanation

An underexposed image has insufficient photons reaching the detector, producing noise that cannot be recovered by display processing. Increasing mAs raises the number of detected photons and restores the exposure index to the target range, at the cost of a modest dose increase.

Question 9Physics, Instrumentation and Radiation Safety

Which factor primarily determines the spatial resolution limit of a flat-panel detector?

  1. Detector element (del) size Correct answer.
  2. Beam filtration
  3. Quantum detection efficiency
  4. Tube current

Explanation

Spatial resolution in a flat-panel detector is fundamentally limited by the size of the detector elements, with smaller dels allowing higher resolution. Quantum detection efficiency and tube current affect noise and dose, not the geometric resolution limit.

Question 10Physics, Instrumentation and Radiation Safety

A 70 kg patient undergoes a CT examination with a volume CT dose index of 20 mGy and a dose-length product of 600 mGy·cm. What is the approximate effective dose using a conversion factor of 0.015 mSv/(mGy·cm)?

  1. 90 mSv
  2. 1.2 mSv
  3. 0.9 mSv
  4. 9.0 mSv Correct answer.

Explanation

Effective dose is estimated by multiplying the dose-length product by the appropriate region-specific conversion factor. Here 600 mGy·cm multiplied by 0.015 mSv/(mGy·cm) gives 9.0 mSv, which is a typical magnitude for a multiphase abdominal CT.

Question 11Physics, Instrumentation and Radiation Safety

Which statement correctly describes the relationship between tube voltage and subject contrast in projection radiography?

  1. Lower kVp increases subject contrast Correct answer.
  2. kVp has no effect on subject contrast
  3. Subject contrast depends only on mAs
  4. Higher kVp increases subject contrast

Explanation

Lowering kVp shifts the beam toward lower energies where photoelectric absorption differences between tissues are greater, thereby increasing subject contrast. Higher kVp produces a more penetrating beam with more Compton interactions and reduced contrast.

Question 12Physics, Instrumentation and Radiation Safety

In magnetic resonance imaging, which safety concern applies to a patient with an implanted cardiac pacemaker?

  1. Ionizing radiation exposure
  2. Projectile and torque effects from the static field Correct answer.
  3. Nephrogenic systemic fibrosis
  4. Thermal injury from radiofrequency only

Explanation

The static magnetic field can exert translational force and torque on ferromagnetic components of a pacemaker and may also induce currents or reprogram the device. MR safety screening therefore classifies such devices and often contraindicates scanning unless the device is MR-conditional.

Question 13Physics, Instrumentation and Radiation Safety

A CT protocol uses a pitch of 2.0 with a 64-slice scanner. What is the principal effect of this pitch on patient dose and image noise compared with a pitch of 1.0?

  1. Dose decreases and noise increases Correct answer.
  2. Dose and noise both decrease
  3. Dose and noise both increase
  4. Dose increases and noise decreases

Explanation

Increasing pitch speeds the table through the gantry, so the tube current per unit length of patient decreases, lowering dose. Because fewer photons are sampled per slice, image noise increases unless tube current is raised to compensate.

Question 14Physics, Instrumentation and Radiation Safety

Which of the following describes the purpose of beam filtration in a diagnostic X-ray tube?

  1. To remove low-energy photons that would only contribute to patient dose Correct answer.
  2. To focus the beam toward the detector
  3. To increase the tube output
  4. To reduce the focal spot size

Explanation

Added filtration preferentially absorbs low-energy photons that would be absorbed in superficial tissue without contributing to the image, thereby reducing skin dose and hardening the beam. It does not increase output or affect focal spot geometry.

Question 15Physics, Instrumentation and Radiation Safety

A fluoroscopy system displays an entrance surface air kerma rate of 40 mGy/min during a procedure that lasts 5 minutes. What is the approximate total entrance surface air kerma?

  1. 200 mGy Correct answer.
  2. 20 mGy
  3. 2000 mGy
  4. 8 mGy

Explanation

Total entrance surface air kerma is the product of the rate and the exposure time, so 40 mGy/min multiplied by 5 minutes equals 200 mGy. This value is used to compare against threshold levels for deterministic skin effects.

Question 16Physics, Instrumentation and Radiation Safety

Which detector type converts X-ray photons directly into an electrical charge without an intermediate light stage?

  1. Photostimulable phosphor plate
  2. Indirect flat-panel with cesium iodide
  3. Direct flat-panel with amorphous selenium Correct answer.
  4. Screen-film with rare-earth phosphor

Explanation

Direct conversion detectors use a photoconductor such as amorphous selenium that converts absorbed X-ray energy into electron-hole pairs, which are collected by a thin-film transistor array. Indirect systems first convert X-rays to light in a scintillator before generating charge.

Question 17Physics, Instrumentation and Radiation Safety

An interventional radiologist standing behind a mobile lead screen during a long procedure wants to minimize occupational dose. Which action provides the greatest reduction in dose from scattered radiation?

  1. Increasing the field size
  2. Increasing the distance from the patient Correct answer.
  3. Maximizing the use of magnification mode
  4. Reducing the use of pulsed fluoroscopy

Explanation

Scattered radiation intensity falls with the square of distance from the patient, who is the scatter source, so increasing distance yields a large dose reduction. Lead shielding and collimation complement this but distance is the most powerful single factor.

Question 18Physics, Instrumentation and Radiation Safety

A CT image reconstructed with a sharp (bone) kernel compared with a smooth (soft tissue) kernel will demonstrate which of the following?

  1. Higher spatial resolution and lower noise
  2. Lower spatial resolution and higher noise
  3. Lower spatial resolution and lower noise
  4. Higher spatial resolution and higher noise Correct answer.

Explanation

Sharp reconstruction kernels enhance high-frequency information, improving spatial resolution at the cost of amplifying noise. Smooth kernels suppress high frequencies, reducing noise but blurring fine detail.

Question 19Physics, Instrumentation and Radiation Safety

Which statement about the dose-area product in fluoroscopy is most accurate?

  1. It measures peak skin dose at a single point
  2. It is independent of field size
  3. It integrates air kerma over the beam cross-sectional area Correct answer.
  4. It is expressed in millisieverts

Explanation

Dose-area product is the integral of air kerma over the irradiated area and is expressed in Gy·cm², providing a measure of total radiation energy delivered to the patient. It does not indicate local peak skin dose, which requires information about beam position and geometry.

Question 20Physics, Instrumentation and Radiation Safety

A department wishes to reduce CT dose while maintaining diagnostic image quality. Which strategy is most consistent with current optimization principles?

  1. Increasing the reconstruction slice thickness only
  2. Applying automatic exposure control with size-specific protocols Correct answer.
  3. Using a fixed high mAs for all patients
  4. Removing all beam filtration

Explanation

Automatic exposure control combined with size-specific protocols adjusts tube current to patient attenuation, reducing dose in smaller patients while preserving image quality. Fixed high mAs ignores patient size and unnecessarily raises dose.

Question 21Thoracic Imaging

A 24-year-old man presents with sudden right-sided pleuritic chest pain and breathlessness after lifting weights. Chest radiograph shows a visceral pleural line with no lung markings beyond it, and the lung edge lies lateral to the mid-clavicular line at the apex. What is the most appropriate next step in management?

  1. Immediate needle decompression of the right hemithorax
  2. Observation with supplemental oxygen and repeat radiograph in 6 hours
  3. Insertion of a chest drain Correct answer.
  4. Discharge with analgesia and outpatient review

Explanation

A primary spontaneous pneumothorax with a visible lung edge and no haemodynamic compromise is usually managed with aspiration or a chest drain depending on size and symptoms; a large pneumothorax in a symptomatic patient warrants drainage. Needle decompression is reserved for tension pneumothorax with haemodynamic instability, which this patient does not have. Observation alone is appropriate only for small, asymptomatic pneumothoraces.

Question 22Thoracic Imaging

On a chest radiograph, which feature most reliably distinguishes a tension pneumothorax from a simple pneumothorax?

  1. Contralateral mediastinal shift with flattening of the ipsilateral hemidiaphragm Correct answer.
  2. Increased radiolucency of the affected hemithorax
  3. A visible visceral pleural line
  4. Absence of lung markings peripheral to the pleural line

Explanation

Tension pneumothorax is defined by mass effect: mediastinal shift away from the affected side, depression or flattening of the ipsilateral hemidiaphragm, and sometimes widening of the intercostal spaces. A pleural line, absent peripheral markings, and hemithorax lucency occur in any pneumothorax and do not indicate tension.

Question 23Thoracic Imaging

A 68-year-old smoker has a 3 cm peripheral lung nodule abutting the pleura. Which imaging feature on contrast-enhanced CT most strongly suggests that the nodule is malignant rather than a benign lesion?

  1. Uniform internal fat attenuation
  2. Spiculated margins with pleural tagging Correct answer.
  3. Diffuse stippled calcification
  4. Smooth, well-defined margins

Explanation

Spiculated or lobulated margins with pleural retraction (pleural tagging) are classic features of malignancy arising from desmoplastic reaction and irregular growth. Smooth margins, fat content, and diffuse benign-pattern calcification favour a benign aetiology.

Question 24Thoracic Imaging

Which pattern of calcification in a solitary pulmonary nodule is considered benign?

  1. Central, diffuse, laminated, or popcorn calcification Correct answer.
  2. Eccentric calcification
  3. Punctate calcification within a spiculated nodule
  4. Amorphous calcification

Explanation

Benign patterns of nodule calcification include central, diffuse, laminated, and popcorn types, reflecting granulomatous disease or hamartoma. Eccentric, amorphous, or punctate calcification within a spiculated nodule raises concern for malignancy.

Question 25Thoracic Imaging

A 55-year-old woman with a history of breast cancer presents with progressive dyspnoea. Chest radiograph shows multiple small nodules distributed along the fissures and at the lung bases, with beaded thickening of the interlobular septa. What is the most likely diagnosis?

  1. Pulmonary alveolar proteinosis
  2. Centrilobular emphysema
  3. Sarcoidosis
  4. Lymphangitic carcinomatosis Correct answer.

Explanation

Nodular thickening of the interlobular septa, fissural beading, and a basal predominance in a patient with a known malignancy are characteristic of lymphangitic carcinomatosis. Emphysema shows lucent destruction without septal thickening, sarcoidosis typically produces perilymphatic nodules with upper-zone predominance, and alveolar proteinosis produces ground-glass with a crazy-paving pattern.

Question 26Thoracic Imaging

On high-resolution CT, which distribution of nodules is most characteristic of sarcoidosis?

  1. Random distribution throughout the lungs
  2. Perilymphatic distribution with upper and mid zone predominance Correct answer.
  3. Miliary distribution with relative apical sparing
  4. Centrilobular distribution with lower lobe predominance

Explanation

Sarcoidosis classically produces perilymphatic nodules along the bronchovascular bundles, interlobular septa, and subpleural regions, with upper and mid zone predominance and bilateral hilar lymphadenopathy. Random and miliary patterns suggest haematogenous spread such as metastases or tuberculosis, and centrilobular nodules suggest bronchiolar disease.

Question 27Thoracic Imaging

A 72-year-old man with chronic obstructive pulmonary disease has a chest radiograph showing a large, thin-walled lucency in the right upper lobe with a discernible wall and compressed adjacent lung. What is the most likely diagnosis?

  1. Bullous emphysema Correct answer.
  2. Lung abscess
  3. Cavitating squamous cell carcinoma
  4. Tension pneumothorax

Explanation

A bulla is a thin-walled, air-filled space with a visible wall and compressed adjacent lung, commonly seen in emphysema. Carcinoma and abscess usually show thick, irregular walls, and tension pneumothorax shows mass effect with a pleural line rather than a complete wall.

Question 28Thoracic Imaging

Which chest radiographic sign is most suggestive of a left lower lobe collapse?

  1. A retrosternal lucency on the lateral view
  2. Elevation of the left hemidiaphragm with a preserved cardiac silhouette
  3. Loss of the left hemidiaphragm silhouette with a triangular opacity behind the heart Correct answer.
  4. The 'sail sign' in the left upper zone

Explanation

Left lower lobe collapse produces a triangular opacity behind the heart on the frontal view and silhouettes the left hemidiaphragm, with the left heart border preserved. The sail sign indicates right upper lobe collapse, and retrosternal lucency is a feature of hyperinflation.

Question 29Thoracic Imaging

A 30-year-old man is found unresponsive after a road traffic accident. CT shows a left-sided haemothorax, and a chest drain is inserted. Which chest radiographic finding most strongly suggests ongoing active arterial bleeding?

  1. A small apical pleural collection
  2. A persistent hazy opacity that does not change on serial radiographs
  3. Blunting of the costophrenic angle only on the erect view
  4. A rapidly enlarging pleural opacity on serial radiographs Correct answer.

Explanation

Rapid accumulation of pleural blood on serial radiographs, particularly more than 200 mL per hour, suggests active arterial haemorrhage and may indicate the need for angiography and embolisation or surgery. A static opacity, minimal blunting, or a small apical collection does not indicate active bleeding.

Question 30Thoracic Imaging

Which feature on a chest radiograph most reliably indicates left atrial enlargement?

  1. Splaying of the carina to an angle greater than 90 degrees with a double right heart border Correct answer.
  2. Double right heart border
  3. Increased cardiothoracic ratio above 0.5 alone
  4. Prominent aortic knuckle

Explanation

Left atrial enlargement produces splaying of the carinal angle beyond 90 degrees, a double right heart border from the enlarged atrium projecting to the right, and prominence of the left atrial appendage. A prominent aortic knuckle reflects aortic disease, and an increased cardiothoracic ratio alone indicates cardiomegaly without specifying chamber.

Question 31Thoracic Imaging

A 45-year-old woman has a chest radiograph showing bilateral hilar lymphadenopathy with right paratracheal lymphadenopathy and no parenchymal opacities. Which diagnosis is most likely?

  1. Pulmonary tuberculosis
  2. Sarcoidosis Correct answer.
  3. Lymphoma
  4. Primary lung carcinoma

Explanation

Bilateral symmetrical hilar lymphadenopathy with right paratracheal adenopathy (the 1-2-3 sign) and no parenchymal disease is typical of sarcoidosis stage I. Tuberculosis usually causes unilateral adenopathy with parenchymal disease, lymphoma tends to be asymmetric, and primary lung carcinoma typically produces a unilateral mass.

Question 32Thoracic Imaging

Which feature on a chest radiograph is characteristic of a pulmonary arteriovenous malformation?

  1. A thin-walled apical bulla
  2. A triangular opacity at the lung base with volume loss
  3. A miliary pattern of tiny nodules
  4. A well-defined rounded opacity with a feeding artery and draining vein Correct answer.

Explanation

A pulmonary arteriovenous malformation appears as a rounded or lobulated opacity connected to the hilum by a feeding artery and draining vein, often best seen on CT angiography. Bullae, lobar collapse, and miliary nodules have entirely different appearances.

Question 33Thoracic Imaging

Which CT finding is most specific for usual interstitial pneumonia in a patient with suspected idiopathic pulmonary fibrosis?

  1. Honeycombing with peripheral and basal predominance and traction bronchiectasis Correct answer.
  2. Diffuse ground-glass opacity with smooth septal thickening
  3. Ground-glass opacity with consolidation
  4. Centrilobular nodules

Explanation

The hallmark of usual interstitial pneumonia is subpleural, basal-predominant honeycombing with traction bronchiectasis and minimal ground-glass change. Centrilobular nodules suggest bronchiolar disease, and ground-glass with consolidation or smooth septal thickening suggests other patterns such as organising pneumonia or alveolar proteinosis.

Question 34Thoracic Imaging

A 60-year-old man with fever, cough, and pleuritic pain has a chest radiograph showing a wedge-shaped peripheral opacity abutting the pleura in the right mid zone. What is the most likely diagnosis?

  1. Bronchoalveolar carcinoma
  2. Pneumonia Correct answer.
  3. Pulmonary oedema
  4. Pulmonary infarction

Explanation

A wedge-shaped, peripheral opacity abutting the pleura in a febrile patient with cough and pleuritic pain is most consistent with community-acquired pneumonia. Pulmonary infarction can mimic this but usually occurs in the setting of pulmonary embolism and often cavitates; oedema is typically bilateral and perihilar.

Question 35Thoracic Imaging

Which radiographic finding is most consistent with a large left-sided pleural effusion?

  1. A homogeneous opacity with a meniscus and contralateral mediastinal shift Correct answer.
  2. A homogeneous opacity with an air-fluid level
  3. A homogeneous opacity with a meniscus and ipsilateral mediastinal shift
  4. A meniscus sign with blunting of the costophrenic angle on the erect view

Explanation

A large pleural effusion produces a homogeneous opacity with a meniscus and, when large enough, pushes the mediastinum away from the effusion (contralateral shift). Ipsilateral shift suggests volume loss such as collapse or fibrosis, and an air-fluid level suggests a hydropneumothorax.

Question 36Thoracic Imaging

A 65-year-old man with a 40 pack-year smoking history has a chest radiograph showing a right hilar mass with ipsilateral mediastinal widening and elevation of the right hemidiaphragm. Which finding best explains the hemidiaphragm elevation?

  1. Compensatory hyperinflation
  2. Pleural effusion
  3. Phrenic nerve involvement by tumour Correct answer.
  4. Right lower lobe consolidation

Explanation

Elevation of a hemidiaphragm in the presence of a hilar mass suggests phrenic nerve palsy from tumour invasion, which paralyses the diaphragm. Consolidation, effusion, and hyperinflation do not typically cause isolated hemidiaphragm elevation in this context.

Question 37Thoracic Imaging

Which feature on CT pulmonary angiography is the direct sign of acute pulmonary embolism?

  1. Peripheral wedge-shaped opacity
  2. An intraluminal filling defect within a contrast-opacified pulmonary artery Correct answer.
  3. Mosaic attenuation of the lung parenchyma
  4. Enlargement of the main pulmonary artery

Explanation

The direct sign of acute pulmonary embolism on CT pulmonary angiography is an intraluminal filling defect within a contrast-opacified pulmonary artery, which may be central or eccentric. Mosaic attenuation, peripheral wedge opacity (Hampton hump), and main pulmonary artery enlargement are indirect signs.

Question 38Thoracic Imaging

A 28-year-old woman with a history of asthma presents with fever and a chest radiograph showing a thin-walled cystic space with an air-fluid level in the right lower lobe. Which diagnosis should be considered first?

  1. Hydatid cyst
  2. Bronchogenic cyst
  3. Cavitating pneumonia Correct answer.
  4. Congenital cystic adenomatoid malformation

Explanation

A thin-walled cystic space with an air-fluid level in a febrile patient suggests a cavitating pneumonia or lung abscess, particularly with a history of asthma and possible aspiration. Hydatid cysts, congenital malformations, and bronchogenic cysts are usually incidental and not associated with acute fever.

Question 39Thoracic Imaging

Which of the following is the most appropriate initial imaging investigation for a haemodynamically stable patient with suspected acute pulmonary embolism?

  1. CT pulmonary angiography Correct answer.
  2. Ventilation-perfusion scintigraphy
  3. Chest radiograph alone
  4. Conventional pulmonary angiography

Explanation

CT pulmonary angiography is the first-line investigation for suspected acute pulmonary embolism in a stable patient because it directly visualises thrombus and provides alternative diagnoses. Ventilation-perfusion scintigraphy is reserved for contraindications to contrast, conventional angiography is invasive, and a chest radiograph alone is insufficient.

Question 40Thoracic Imaging

A 50-year-old man with long-standing mitral stenosis presents with haemoptysis. Chest radiograph shows prominent upper lobe pulmonary veins, indistinct central vessels, and Kerley B lines. Which mechanism best explains these findings?

  1. Left heart failure with elevated pulmonary venous pressure Correct answer.
  2. Chronic thromboembolic disease
  3. Right heart failure with reduced pulmonary blood flow
  4. Pulmonary arterial hypertension

Explanation

Elevated left atrial and pulmonary venous pressures cause cephalisation of pulmonary blood flow, perivascular oedema with indistinct central vessels, and interlobular septal thickening (Kerley B lines). Pulmonary arterial hypertension causes enlarged central arteries with peripheral pruning, and right heart failure causes reduced pulmonary flow.

Question 41Cardiovascular Imaging

A 58-year-old man with atypical chest pain undergoes coronary CT angiography. The Agatston calcium score is reported as 0. How should this result be interpreted?

  1. The study is non-diagnostic and must be repeated with a higher tube voltage
  2. Coronary artery disease is definitively excluded
  3. A significant stenosis is present in at least one vessel
  4. No calcified coronary plaque is detected, but non-calcified plaque may still be present Correct answer.

Explanation

The Agatston score quantifies only calcified atherosclerotic plaque, so a score of zero means no detectable coronary calcification. It does not exclude non-calcified (soft) plaque, which can still cause stenosis and is assessed on the contrast-enhanced angiographic phase.

Question 42Cardiovascular Imaging

Which coronary artery most commonly supplies the sinoatrial node in the general population?

  1. Left main coronary artery
  2. Left circumflex artery
  3. Left anterior descending artery
  4. Right coronary artery Correct answer.

Explanation

In most individuals the sinoatrial node is supplied by a branch of the right coronary artery, usually the SA nodal branch arising proximally. A minority have supply from the left circumflex, which is a recognised anatomic variant.

Question 43Cardiovascular Imaging

On a contrast-enhanced chest CT, a Stanford type A aortic dissection is characterised by which finding?

  1. An intimal flap involving the ascending aorta Correct answer.
  2. A focal outpouching of the aortic arch without a flap
  3. An intimal flap confined to the descending aorta distal to the left subclavian artery
  4. Circumferential mural thickening of the descending aorta without a false lumen

Explanation

The Stanford classification divides dissections by involvement of the ascending aorta: type A involves the ascending aorta regardless of distal extent, while type B spares it. Identifying flap extension into the ascending aorta is therefore the key discriminator.

Question 44Cardiovascular Imaging

A 70-year-old woman with sudden dyspnoea undergoes CT pulmonary angiography. Which finding is the most direct sign of acute pulmonary embolism?

  1. Bilateral smooth septal thickening with dependent oedema
  2. Diffuse ground-glass opacity with air bronchograms
  3. A calcified mural plaque along the pulmonary artery wall
  4. A complete intraluminal filling defect within a contrast-opacified pulmonary artery Correct answer.

Explanation

Acute pulmonary embolism appears on CT pulmonary angiography as a low-attenuation filling defect within the contrast-filled pulmonary arterial lumen, either centrally or as a partial defect. This is the direct angiographic sign of thrombus.

Question 45Cardiovascular Imaging

Which radiographic feature is most characteristic of left atrial enlargement on a frontal chest radiograph?

  1. Straightening of the left heart border with a prominent aortic knob
  2. Caudal displacement of the right hilum
  3. Double right heart border with splaying of the carina Correct answer.
  4. Hyperinflation with flattened hemidiaphragms

Explanation

Left atrial enlargement produces a double right heart border where the enlarged atrium projects to the right of the right atrium, and it widens the carinal angle by elevating the left main bronchus. These signs reflect the central and posterior position of the left atrium.

Question 46Cardiovascular Imaging

A 62-year-old man with acute tearing chest pain has a CT showing a high-attenuation crescent within the aortic wall but no visible intimal flap on the non-contrast phase. Which diagnosis best fits this finding?

  1. Penetrating atherosclerotic ulcer
  2. Aortic intramural haematoma Correct answer.
  3. Mycotic aneurysm
  4. Aortic intramural thrombus in an aneurysm sac

Explanation

A crescentic high-attenuation thickening of the aortic wall on non-contrast CT represents fresh blood within the media, the hallmark of aortic intramural haematoma. It belongs to the acute aortic syndrome spectrum and can occur without a demonstrable flap.

Question 47Cardiovascular Imaging

A 45-year-old woman with recurrent pulmonary emboli is evaluated for chronic thromboembolic pulmonary hypertension. Which CT pulmonary angiographic finding most supports chronic rather than acute disease?

  1. Bilateral dependent consolidation with pleural effusions
  2. Central filling defect surrounded by contrast in a dilated vessel
  3. Complete occlusion of a segmental artery with vessel enlargement
  4. Eccentric mural thrombus with web-like bands and vessel narrowing Correct answer.

Explanation

Chronic thromboembolic disease produces eccentric, mural-adherent thrombus that becomes incorporated into the vessel wall, together with webs, bands, and abrupt vessel narrowing or pruning. Acute emboli instead appear as central defects that may be surrounded by contrast.

Question 48Cardiovascular Imaging

A patient with a bicuspid aortic valve is being assessed for thoracic aortic dilatation. Which site is most classically predisposed to aneurysm formation in this condition?

  1. Abdominal aorta below the renal arteries
  2. Aortic arch between the great vessels
  3. Aortic root and ascending aorta Correct answer.
  4. Proximal descending aorta

Explanation

Bicuspid aortic valve is associated with aortopathy affecting the aortic root and ascending aorta, where dilatation and dissection risk are increased. This pattern relates to abnormal medial connective tissue and altered haemodynamics.

Question 49Cardiovascular Imaging

A 55-year-old man has an incidental finding of a 4.5 cm saccular aneurysm at the aortic arch on CT. Which feature most increases concern for a symptomatic or impending rupture?

  1. Smooth calcified margins with stable dimensions over two years
  2. Uniform fusiform dilatation with mural calcification
  3. Focal eccentric outpouching with adjacent periaortic stranding Correct answer.
  4. Presence of a small atherosclerotic plaque at the aneurysm neck

Explanation

A saccular outpouching with periaortic stranding suggests an unstable or inflammatory process and raises concern for impending rupture. Saccular morphology itself is also considered higher risk than fusiform dilatation at comparable size.

Question 50Cardiovascular Imaging

On cardiac MRI, late gadolinium enhancement in a subendocardial distribution corresponding to a coronary territory most likely indicates which process?

  1. Hypertrophic cardiomyopathy
  2. Myocarditis
  3. Myocardial infarction with scar Correct answer.
  4. Cardiac amyloidosis

Explanation

Late gadolinium enhancement following a coronary vascular territory in a subendocardial or transmural pattern is the classic signature of ischaemic scar. Non-ischaemic patterns are typically mid-wall or epicardial and do not respect coronary boundaries.