CASES

1. CASES Dr. Satish, R2, Dept of Radiodiagnosis, SSGH, Baroda, 09-09-2008

2. CASE 1 Forty year-old female presents to the emergency department complaining of dizziness, shortness of breath and epigastric pain migrating downward. She is hypotensive as well.

3. CHEST RADIOGRAPH Abnormal contour of the mediastinum with the left paraspinal stripe poorly delineated.

4. Dissection extending from the aortic root to the level of the renal arteries with associated hemopericardium. CT ANGIOGRAPHY

5. AORTIC DISSECTION • It is the most common acute emergency affecting the aorta. Predisposing factors • Hypertension in 90% cases. • Cystic medial degeneration (e.g., Marfan syndrome) • Coarctation of aorta • Bicuspid aortic valve • Aortitis • Pregnancy • Iatrogenic trauma

6. CLASSIFICATIONS OF AORTIC DISSECTION DeBakey Classification • Type I (originates in ascending aorta and extends a variable distance beyond the aortic arch) • Type II (confined to ascending aorta) • Type III (originates distal to left subclavian artery and extends a variable distance distally) Stanford’s Classification • TYPE A (involvement of aorta proximal to origin of left subclavian artery, regardless of site of intimal tear or distal extent)-60% cases • TYPE B ( confined to descending aorta)- 40% cases

7. Diagnosis Plain chest radiography • Plain film findings include • widening of the mediastinum and aortic contour • change in aortic configuration from prior examination • displaced intimal calcification more than 1 cm from outer wall of aortic shadow. • They are frequently nonspecific and may only be apparent in retrospect.

8. Plain chest x-ray showing acute type A dissection such as a widened mediastinum, rightward tracheal displacement, irregular aortic contour with loss of the aortic knob, an indistinct aortopulmonary window, and a left pleural effusion.

9. CT scan • Helical CT is highly accurate in diagnosing aortic dissection with a sensitivity and specificity of nearly 100%. • CT scans in 70% of cases of acute aortic dissection depict an intimal flap. • CT also is useful for identifying atypical forms of dissection, such as intramural hematoma (IMH) & penetrating atherosclerotic ulcer. • Definitive finding of aortic dissection on CT is the demonstration of two contrast-filled lumen separated by an intimal flap.

10. NCCT: displaced intimal calcification (arrows) in descending aorta. Small bilateral pleural effusions also present. CECT : an intimal flap (arrowheads) seen separating contrast-filled true (t) & false (f) lumina. No intimal flap is seen in the mildly dilated ascending aorta (AA):Type B aortic dissection

11. Precontrast images • Internal displacement of intimal calcification • Visible intimal flap as linear structure slightly higher in attenuation than surrounding blood • High attenuation thrombosed false lumen, if it has thrombosed acutely. • Enlargement of long segment of the aorta 5. Pericardial, mediastinal, and/or pleural hemorrhage, secondary to rupture

12. Internal displacement of intimal calcification : Stanford type B typical aortic dissection. NCCT depicts displaced intimal calcifications (arrow) in the descending aorta

13. High attenuation thrombosed false lumen, if it has thrombosed acutely. Type A aortic dissection, thrombosed false lumen. NCCT : a peripheral rim of high attenuation (small arrows), which represents acutely thrombosed false lumen, is seen within ascending & descending aorta.

14. Hemopericardium (large arrows) in case of Type A aortic dissection.

15. Postcontrast images • Contrast-filled true and false lumen separated by intimal flap; false lumen typically seen in outer curvature of aorta • Delayed enhancement of the false lumen because of slower flow • Thrombosis of false lumen, with only enhancement of true lumen • Compression of true lumen by thrombosed false lumen • Extension of dissection into branch vessels 6. Ischemia/infarction of organs supplied by branch vessels from false lumen

16. Contrast-filled true and false lumen separated by intimal flap Contrast-filled true and false lumina in ascending and descending aorta are separated by an intimal flap (arrows). V, compressed superior vena cava.

17. Delayed enhancement of false lumen because of slower flow , false lumen typically seen in outer curvature of aorta CECT during early portion of contrast administration : opacification of compressed true lumen (t). The larger false lumen (f) is only partially opacified because of slower flow.

18. Chronic type B aortic dissection. Calcification (arrows) of endothelialized surface of false lumen (f) in a chronic aortic dissection (may mimic the peripheral calcification seen in aortic aneurysms.)A focus of displaced intimal calcification (arrowhead) is seen between the opacified true (t) and false lumina (f).

19. CECT at the level of kidneys demonstrates lack of enhancement of posterior aspect of left kidney (K), likely secondary to inadequate blood flow from false lumen. Arrowhead, intimal flap in abdominal aorta : Aortic dissection with renal ischemia.

20. Distinction between the True lumen & False lumen is importantfor planning endovascular treatment of dissection.

21. Four signs to differentiate are: 1. Cobweb sign in false lumen: Slender linear areas of low attenuation that occasionally appearin false lumen on CT images, known as cobweb sign & arespecific to false lumen. Thesefindings correspond to residual ribbons of media, incompletelysheared away during dissection process . Stanford type B aortic dissection. CECT show a : cobweb sign (arrow)—linear traces of low attenuation—in false lumen.

22. 2.False lumen has usually a larger cross-sectional area than true lumen. 3.Beak sign is cross-sectional imaging manifestation of wedge of hematoma that cleaves a space for propagation of false lumen. Stanford type B aortic dissection. Beak sign (arrowhead) is caused by a wedge-shaped protrusion of hematoma in false lumen. The true lumen is compressed & adopts a crescent shape.

23. 4.On mostcontrast-enhanced CT scans, true lumen may be identifiedby its continuity with an undissected portion of the aorta.

24. Atypical configurations of Intimal Flap Atypical configurations are as follows: • dissection of entire intima with a circumferential intimal flap • a filiform (extremely narrow) true lumen, which can have ischemic complications • a calcified false lumen in chronic dissection • a three-channel aorta (Mercedes-Benz sign) or an aorta with several false channels • intimointimal intussusception

25. Dissection of entire intima. CECT shows dissection of entire intima in thoracic descending aorta (arrow) . Intima may invaginate like a windsock & result in intimointimal intususception

26. Filiform (extremly narrow) true lumen :CECT shows a filiform true lumen in thoracic descending aorta (arrow).

27. Calcified false lumen. CECT scan shows an abdominal aortic dissection with mural calcification of false lumen (arrows) : seen in chronic dissection

28. Three-channel aorta. CT angiogram shows two false lumina (F) in thoracic descending aorta. The intimal flap demonstrates Mercedes-Benz sign.

29. Branch vessel involvement in dissection • Obstruction of aortic branch vessel adds substantially to mortality and morbidity rates in patients with aortic dissection.The frequency of such obstruction after dissection is as highas 27%. • There are two types of branch-vessel occlusion. 1. In static obstruction, intimal flap intersects or enters the branch-vessel origin. Static obstruction is treated locally with an intravascularstent.

30. Static obstruction of left renal artery.CECT scan obtained at a lower level shows intimal flap (white arrow) entering left renal artery and producing a left renal infarct (black arrow).

31. 2. In dynamic obstruction, the intimal flap spares the branch-vesselwall but prolapses across the branch-vessel origin and coversit like a curtain. Dynamic obstruction is treated witha fenestration procedure. In dynamic obstruction, theintimal flap has an ischemic configuration: The true lumen resemblesa C-shaped envelope that is predominantly concave toward thefalse lumen. Presence of an ischemic configuration should beconfirmed with manometry of the true and false lumina.

32. Dynamic obstruction of the renal artery. (a) Enhanced CT scan shows dynamic obstruction of the right renal artery (black arrow) and infarction of the right kidney (white arrows). (b) Coronal MPR image obtained at the level of the renal arteries shows a collapsed true lumen (black arrow) at the right renal ostium (white arrow).

33. CASE 2 A 47 Yr male C/O slow growing mass on the palmar aspect of his right hand.

34. T1 Coronal T2 Coronal with fat saturation • Small, lobular, circumscribed lesion anterior to small finger flexor tendon at level of metacarpophalangel joint , Hypointense to muscle on T1WI & heterogenous signal on T2WI

35. T1 Axial & T1 Axial post Gadolinium with fat saturation: • Mild heterogenous enhancement • No apparent involvement of underlying structures

36. The location and appearance of this lesion is typical of a Giant Cell Tumor of the Tendon Sheath. This entity is the second most common soft tissue mass in the hand and wrist Represents an extraarticular form of pigmented villonodular synovitis (PVNS). These lesions are located in proximity to a tendon and demonstrate hypointense signal on T1WI heterogenous signal on T2WI (due to hemosiderin deposition).

37. D/D • Synovial Sarcoma • Malignant Fibrous Histiocytoma • Ganglion cyst

38. Synovial Sarcoma Lesions typically occur in a younger population (15-30 years of age). They usually originate outside the joint, often in the lower extremities (especially about the knee and ankle). Dystrophic calcification is commonly demonstrated on plain radiographs. The MRI appearance is - usually well defined and relatively benign.

39. MRI without contrast, demonstrating a soft tissue tumor just proximal to sesamoid.MRI with gadolinium contrast : increased enhancement of soft tissue mass

40. Malignant fibrous histiocytoma • The most common soft tissue sarcoma of late adult life. • most often occurs in the extremities (lower more common than upper). • It presents as an enlarging painless soft tissue mass in the thigh, typically 5-10 cm in diameter.

41. Axial MRI T1 : an intramuscular soft tissue mass, - biopsy proven malignant fibrous histiocytoma.

42. GANGLION CYST Wrist cyst, Bible cyst, or Dorsal tendon cyst • Most common soft tissue mass of the hand. • It is a fluid filled sac which can be felt below the skin. • It is usually attached to a tendon sheath (lining which lubricates the tendon) in the hand or wrist or connected with an underlying joint

43. MRI showing characteristic features of ganglion of dorsal aspect of wrist. Focal, relatively large mass (arrows) is evident on T1-weighted image.Corresponding fast spin-echo T2-weighted axial image shows focal, fluid cystic mass (arrows) with internal septa (asterisk). After administration of IV contrast agent, wall enhancement is evident (arrows).

44. 15-30 Yrs 50-60 Yrs 20-40 Yrs Age 40-50 Yrs F>M 3:2 M>F 2:1 sex Equal F>M LL UL UL-hands & fingers LL Location Homogenous/ Heterogenous Heterogenous Homogenous MRI (T2W) Heterogenous

45. CASE 3 • 16 year boy has complaints of burning micturation and increased frequency of urine.

46. Tubular, fluid-filled structure arising from dome of urinary bladder without communication with umbilicus or anterior abdominal wall. No evidence of hydronephrosis, urolithiasis

47. DIAGNOSIS: • Vesicourachal diverticulum

48. The urachus, or median umbilical ligament, is a midline tubular structure that extends upward from the anterior dome of the urinary bladder toward the umbilicus in the early embryo. • The tubular urachus normally involutes during the latter half of fetal life and remains as a fibrous band with no known function. • There are four types of congenital urachal anomalies that result if this structure is not obliterated by fibrous proliferation: • patent urachus, • urachal sinus, • urachal diverticulum • urachal cyst.

50. These congenital anomalies are twice as common in men as in women. • The most common anomaly is a patent urachus, accounting for approximately 50%, and this anomaly is purely congenital. • The remaining three entities may be congenital or represent normal closure of the urachus after birth with reopening secondary to acquired pathologic conditions. • While the majority of patients with urachal abnormalities (except those with patent urachus) are asymptomatic, symptoms may occur when these are associated with infection or tumor.