Learning Radiology Chapter 3 - Recognizing Normal Cardiac Anatomy

Question-and-Answer flashcards that cover heart size assessment, normal cardiac contours, CT and MRI anatomy levels, coronary anatomy, dominance patterns, calcium scoring, imaging techniques, and key radiographic signs from the lecture material.

What does the cardiothoracic ratio compare?

The widest transverse diameter of the heart to the widest internal diameter of the thoracic rib cage at the level of the diaphragm.

What is the normal cardiothoracic ratio in most adults on full-inspiration PA chest x-ray?

Less than 50 %.

Which cardiac chambers usually produce cardiomegaly visible on chest radiographs?

The ventricles (ventricular enlargement).

Why may a heart with severe aortic stenosis initially appear normal in size on radiographs?

Because the ventricle first undergoes hypertrophy rather than dilatation, reducing the luminal size without enlarging the silhouette.

Which valve abnormality generally causes larger chamber enlargement: regurgitant or stenotic?

Regurgitant valves (volume overload).

Name the first contour on the right side of the heart on a frontal chest x-ray.

Ascending aorta.

Which structure forms the right heart border on a PA chest radiograph?

Right atrium.

What is the normal upper limit for the aortic knob width (measured from the tracheal edge)?

About 35 mm.

How should the main pulmonary artery segment normally appear on frontal chest x-ray?

Concave or flat (may be slightly convex in young females).

Does a normal-sized left atrium form the heart border on a non-rotated frontal chest film?

No, an isolated normal left atrium does not contribute to the border.

What radiographic sign may indicate left atrial enlargement on the right side of the mediastinum?

A “double-density” sign where the enlarged left atrium projects behind the right atrium.

When the descending thoracic aorta becomes tortuous, in which direction does it usually move?

Away from the spine toward the patient’s left.

What imaging feature on chest CT defines the five-vessel level?

Visualization of trachea, esophagus, and brachiocephalic veins plus major arch vessels.

Which space under the aortic arch and above the pulmonary artery is important for detecting lymphadenopathy on CT?

The aortopulmonary window.

At CT, which pulmonary artery is higher: right or left?

Left pulmonary artery.

What mnemonic describes the normal position of the pulmonic valve relative to the aortic valve?

PALS – Pulmonic valve lies Anterior, Lateral, and Superior to the aortic valve.

How thick is the normal pericardium when it can be seen on CT?

About 2 mm.

List three major clinical uses of cardiac CT.

Evaluation of coronary arteries, detection of cardiac masses, assessment of aorta/pericardial disease (including dissection).

What is coronary calcium scoring based on?

Quantifying the amount and density of calcified plaque in the coronary arteries on non-contrast CT to estimate atherosclerotic burden and future risk.

How does a zero calcium score influence clinical interpretation?

It has a high negative predictive value for significant coronary luminal narrowing.

What is a ‘triple rule-out’ CT scan?

An emergent CT protocol that simultaneously evaluates for coronary artery disease, aortic dissection, and pulmonary embolism in acute chest pain.

Which two arteries arise directly from the left coronary artery (left main)?

Left anterior descending (LAD) and circumflex arteries.

Where does the LAD travel and what does it supply?

In the anterior interventricular groove to the apex, supplying most of the left ventricle, septum (via septal branches), and diagonal branches to the anterior wall.

What branch commonly supplies the posterior descending artery (PDA) in right-dominant circulation?

Right coronary artery (RCA).

What percentage of the population is right-dominant for coronary circulation?

The overwhelming majority (≈ 70-90 %).

Which coronary dominance pattern is associated with higher overall mortality?

Left-dominant circulation.

Why is ECG-gating used in both cardiac CT and MRI?

To acquire images during minimal cardiac motion (usually diastole) and reduce motion artifacts.

Name four standard MRI planes or views specifically used for cardiac assessment.

Horizontal long-axis (four-chamber), vertical long-axis (two-chamber), short-axis, and three-chamber views.

Which MRI view best displays the mitral and tricuspid valves simultaneously?

Horizontal long-axis (four-chamber) view.

On MRI short-axis images, which ventricle normally has the thicker wall?

Left ventricle.

In MRI terminology, which sequence type is typically used for functional analysis and shows ‘bright blood’?

Gradient-echo (bright-blood) sequences.

Which MRI sequence type usually provides optimal anatomic (morphologic) detail with ‘black blood’?

Spin-echo (black-blood) sequences.

What radiation concern historically limited wide use of cardiac CT and how has this changed?

Relatively high radiation dose; modern dose-reduction techniques now allow scanning below annual background dose levels.

In a chest x-ray, how far should the ascending aorta normally project relative to the right heart border?

It should not extend farther to the right than the right heart border (right atrium).

What radiographic finding, combined with fainting, angina, and CHF, suggests aortic stenosis on chest x-ray?

Post-stenotic dilatation/enlargement of the ascending aorta extending beyond the right heart border.

Which coronary artery branch often supplies the right ventricular outflow tract (conus)?

Conus branch of the right coronary artery.

What is the typical diameter range of the ascending aorta on CT?

Approximately 2.5 – 3.5 cm.

During CT at the main pulmonary artery level, what airway lies distal to the right upper lobe bronchus before branching into middle and lower lobe bronchi?

Bronchus intermedius.

Which cardiac chamber forms most of the left heart border on PA chest radiograph?

Left ventricle.

What is the primary advantage of MRI over CT in pediatric congenital heart disease evaluation?

No ionizing radiation and superior functional/anatomic information when echocardiography is inconclusive.