Read first the text book: Computed Tomography and Magnetic resonance of the Thorax by Nadich et all

Then go through this exercise to assess your comprehension

1. What are the advantages of CT over conventional radiography in evaluating Mediastinum?

Answer

1. What are the advantages of CT over conventional radiography in evaluating Mediastinum?

• In conventional radiography pathological process can be recognized only when there is a contour abnormality deforming the normal lung-mediastinal interface. With CT because of superior contrast resolution, you can recognize vessels, lymph nodes and masses.
• Transaxial plane of CT imaging is ideal for mediastinal structures which are oriented perpendicular to the axial plane..
• Superimposition of different structures can be easily resolved.

2. What are the indications for CT of Mediastinum?

Answer

2. What are the indications for CT of Mediastinum?

• As a follow up to an abnormality detected by conventional radiography.
• When a mediastinal lesion is anticipated with an established clinical problem.
  • Myasthenia gravis
  • Resistant hyperparathyroidism
  • Lung cancer

3. What is the most common reason for mediastinal widening?

Answer

3. What is the most common reason for mediastinal widening?

• About 50% of times it is due to a vascular anomaly or abnormality. Hence it is very important to have a good understanding of anatomy of the arch and great vessels.

4. I am going to present CT sections at various levels starting from Aortic arch. You are to identify each labeled structure.

Answer

4. I am going to present CT sections at various levels starting from Aortic arch. You are to identify each labeled structure.

A: Arch

B: SVC

C: Trachea

D. Esophagus

E. Anterior Mediastinum: (Triangular configuration.)

5. CT section at the level of Azygous arch

Answer

5. CT section at the level of Azygous arch

A. Aorta

B. SVC

C. AZV

D. Esophagus

E. Pretracheal retrocaval space bounded by Aorta, Trachea and SVC. ( Location of Azygous node)

6. CT section

Answer

6. CT section

A. RBV

B. LBV

C. BA

D. LCCA

E. LSA

F. Trachea

G. Esophagus

7. CT section

Answer

7. CT section

A. RBV.  (Vertical course)

B. LBV (Much more horizontal course. Divides mediastinum into pre and retro vascular compartments)

C. RCCA

D. LCCA

E. RSA

F. LSA

G. Clavicle

8. When IV contrast is indicated, will you give it in right or left sided arm vein and why?

Answer

8. When IV contrast is indicated, will you give it in right or left sided arm vein and why?

• Left. To maximize visualization of left brachiocephalic vein which is a convenient landmark to separate anterior from middle mediastinum.

9. Do you know the sequence of origin of great vessels from aorta?

Answer

9. Do you know the sequence of origin of great vessels from aorta?

• The brachiocephalic artery arises first at the most caudal level of arch.
• The left common carotid artery arises next at a higher level.
• The left subclavian artery is last arising from the posterosuperior portion of arch.

10. What is a four vessel sign? What is its significance?

Answer

10. What is a four vessel sign? What is its significance?

• The level of bifurcation of brachiocephalic artery into common carotid and subcalvian artery varies.  If it occurs inferiorly just above aortic arch it is called four vessel sign.  It is usually associated with anomaly involving aortic arch.

11. CT section through sterna notch.

Answer

11. CT section through sterna notch.

A. Clavicles

B. BA

C. 1st rib

D. RBV

E. LBV

F. LSA

12. CT section through thoracic inlet.

Answer

12. CT section through thoracic inlet.

A. Trachea

B. Thyroid

C. RJV

D. LCCA

E. LVA

F. AS m

G. MS m

The session is over

Close the window to return to the main menu