ACUTE ABDOMEN IMAGING 2.pptxACUTE ABDOMEN IMAGING 2.pptxACUTE ABDOMEN IMAGING 2.pptx

ACUTE ABDOMEN IMAGING 2.pptx

1. Acute abdomen IMAGING PART 1 Moderator – Dr Johny prasad MDRD Assistant professor Presentor – Dr Krishna swetha

2. Introduction The term Acute abdomen defines a clinical syndrome characterised by sudden onset of severe abdominal pain requiring emergency medical and surgical treatment. Rapid and accurate diagnosis of these conditions are must because they have high morbidity and mortality.

3. Causes of acute abdomen

4. ACUTE HEPATITIS Acute hepatitis occurs when the liver suffers an injury with a resulting inflammatory reaction. Patients often present with fever, abdominal pain, and jaundice. Multiple serum lab values are often elevated, including AST, ALT, and GGT. 

5. ULTRASOUND hepatomegaly  (most sensitive sign) >15.5 cm at the midclavicular line  starry sky appearance  has been found to have poor sensitivity and specificity  gallbladder wall thickening variably present may be more closely associated with hepatitis A periportal edema accentuated brightness of portal vein radicle walls the overall echotexture is often decreased.

6. Computed tomography hepatomegaly >15.5 cm at the midclavicular line 4 decreased attenuation around the portal system and at the hepatic hilum (periportal edema ) may be seen diffusely decreased parenchymal attenuation on noncontrast CT possible periportal/hepatoduodenal  lymphadenopathy

7. On MRI T2: increased T2 signal around the portal system (periportal edema ) mild generalized increase in parenchymal signal intensity T1 C+ (Gd): delayed, gradual periportal enhancement IP/OOP: hepatic steatosis   may be apparent

8. Acute cholecystitis Presentation – RUQ pain or epigastric pain On examination – RUQ tenderness 90 percent of cases due to gall stones Associated with fever and leucocytosis

9. Sonographic findings Thickening of GB wall ( more than 3mm) Distension of GB lumen (more than 4 cm) GB stones Pericholecystic fluid collection Hyperemia of GB wall on Doppler Prominent cystic artery

10. Acalculous cholecystitis

11. ON CT cholelithiasis:  gallstones   isodense to bile will be missed on CT gallbladder distension gallbladder wall thickening mural or mucosal hyperenhancement pericholecystic fluid  and inflammatory fat stranding high-density bile  enhancement of the adjacent liver parenchyma due to reactive hyperemia tensile gallbladder fundus sign  

12. MR cholangiopancreatography (MRCP) may show an impacted stone in the gallbladder neck or cystic duct as a rounded filling defect. 99mTc-HIDA scintigraphy HIDA cholescintigraphy in acute cholecystitis will demonstrate non-visualization of the gallbladder 4 hours after injection.  

13. Complications of acute cholecystitis Perforation Pericholecystic abscess Peritonitis Empyema gall bladder Fistula formation Gangrenous cholecystitis Emphysematous cholecystitis

14. GANGRENOUS EMPHYSEMATOUS CHOLECYSTITIS CHOLECYSTITIS

15. SECONDARY HEPATIC ABSCESS PSEUDOANEURYSM

16. Acute pancreatitis Presentation – epigastric pain Vomiting,radiating pain to back Causes – gall stones,alchoholism,idiopathic

17. The diagnosis of acute pancreatitis requires two of the following three features: Abdominal pain consistent with acute pancreatitis: Serum lipase or amylase activity at least three times greater than the upper limit of normal. Characteristic findings of acute pancreatitis on contrast-enhanced CT (CECT) and less commonly MRI or US.

18. Sonographic findings GB stone or stone in bile duct Enlargement of pancreas (body – more than 2.4cm and head – 3.5cm ) Decreased gland echogenecity Extrapancreatic inflammation

19. Spectrum of pancreatitis on CT imaging Interstitial pancreatitis Acute peripancreatic collection Pseudocyst of pancreas Necrotising pancreatitis Walled of necrosis

20. CT SEVERITY INDEX

21. INTERSTITIAL PANCREATITIS There is normal enhancement of the entire pancreatic gland with only mild surrounding fatty infiltration. There are no fluid collections and there is no necrosis of the pancreatic parenchyma. CTSI: 2 points.

22. Acute pancreatic collection Preferred locations of fluid collections are: Lesser sac Anterior and posterior pararenal space of the retroperitoneum. Transverse mesocolon Small bowel mesentery. Small bowel mesentery. These collections are the result of the release of activated pancreatic enzymes which also cause necrosis of the surrounding tissues. About 50% of these collections show spontaneous regression .

23. PSEUDOCYST A Pseudocyst is a collection of pancreatic juice or fluid enclosed by a complete wall of fibrous tissue It occurs in interstitial pancreatitis and the absence of necrotic tissue. Communication with the pancreatic duct may be present.

24. NECROTISING PANCREATITIS There are 3 subtypes of necrotizing pancreatitis: Necrosis of  both  pancreatic parenchyma and peripancreatic tissues (most common). Necrosis of  only   extrapancreatic tissue without necrosis of pancreatic parenchyma (less common). Necrosis of pancreatic parenchyma without surrounding necrosis of peripancreatic tissue (very rare). Necrosis of the pancreatic parenchyma can be diagnozed on a contrast-enhanced CT ⩾ 72 hours.

25. Necrosis of peripancreatic tissue can be vary difficult to diagnose, but is suspected when the collection is inhomogeneous, i.e. various densities on CT

26. ACUTE NECROTIC COLLECTION

27. WALLED OF NECROSIS

28. Acute appendicitis Appendicitis is still the most common abdominal emergency In 35 % of cases a fecolith is found at the level of obstruction. In 65 % there is no apparent cause for a mechanical obstruction found Presentation – RLQ pain , fever Leucocytosis , tenderness

29. Sonographic findings Blind ending Tubular Non compressible Non peristaltic More than 6 mm Arising from base of caecum Gut signature sign

30. ON DOPPLER STUDIES Mural or extramural hyperemia with  color flow Doppler  increases the specificity  Vascular flow may be absent in a necrotic segment A  peak systolic velocity  >10 cm/s suggested as a cutoff A  resistive index (RI)  measured at >0.65 may be more specific

31. ON CT ≥8-9 mm outer-to-outer diameter wall thickening (>3 mm), enhancement and stratification if no gangrene thickening of the cecal apex:  cecal bar sign ,  arrowhead sign periappendiceal inflammation fat stranding thickening of the  lateroconal fascia  or  mesoappendix extraluminal fluid, especially if complex

32. Caecal bar sign Presence of inflammatory soft tissue at the ase of ceacum separating contrst filled caecum from appendix

33. Arrow head sign Due to the focal caecum thickening in to the appendicular orifice , the contrast material in the caecum assumes a arrow head sign

34. Supporting features Inflammed perienteric fat Pericaecal collections appendicolith

35. Complications Appendicular mass Appendicular perforation – loculated pericaecal collection . Prominent pericaecal fat . Circumferential loss of submucosal layer of appendix

36. APPENDICULAR MASS US and CT often show a large mass of non-compressible fat around the appendix, often also with wall thickening of neighboring bowel loops.  If there is a circumscribed pus collection, the diagnosis is appendiceal  abscess. If not, the diagnosis is appendi­ceal phlegmon. 

37. Appendicular phelgmon Radiological studies have defined phlegmon differently and often simply referred to severe periappendiceal fat stranding and ill-defined periappendiceal fluid CT Contrast administration is necessary to distinguish phlegmon from an  abscess . Phlegmon is an area of soft tissue or fluid density effacing or displacing usual fat or other connective tissue and shows variable enhancement..

38. Appendicular abscess Appendicular abscesses can arise either in the  peritoneal cavity  or the  retroperitoneal space . Ultrasound fluid collection (hypoechoic) in the appendicular region the appendix may be visualized within the mass CT Shows a fluid collection in the appendicular region with or without internal gas. An appendicolith may often be visualized.

39. Perforated appendix  When appendicitis is left untreated, necrosis (gangrene) of the appendiceal wall can occur and progress to a focal rupture. Focal defect in the enhancing appendiceal wall (most sensitive finding but its performance is heterogeneous across studies ) appendicular abscess  (most specific finding ) extraluminal gas (contained locules or free intraperitoneal gas) extraluminal appendicolith extraluminal leak of enteric contrast

40. Urolithiasis Sonographic findings – echogenic foci . Twinkling artifact . Comet tail artifact

41. PYELONEPHRITIS Pyelonephritis (plural: pyelonephritides ) refers to an  upper urinary (renal) tract infection  with associated  renal pelvis ,  renal calyceal  and  renal parenchymal  inflammation, and comprises a heterogeneous group of conditions Bacterial / acute Pyelonephritis Emphysematous pyelonephritis

42. ACUTE PYELONEPHRITIS Ultrasound is insensitive to the changes of acute pyelonephritis, with most patients having 'normal' scan particulate matter/debris in the collecting system reduced areas of cortical vascularity by using power Dopplerabnormal echogenicity of the renal parenchyma  focal/segmental hypoechoic regions (in edema ) or hyperechoic regions (in hemorrhage ) Ultrasound is, however, useful in assessing for local complications such as  hydronephrosis ,  renal abscess  formation,  renal infarction ,  perinephric collections , and thus may guide management

43. Non-contrast CT often the kidneys appear normal affected parts of the kidney may appear edematous, i.e. swollen and of lower attenuation renal calculi or gas within the collecting system may be evident perinephric stranding : although not considered a useful sign

44. Post-contrast CT one or more focal wedge-like regions will appear swollen and demonstrate reduced enhancement compared with the normal portions of the kidney the periphery of the cortex is also affected, helpful in distinguishing acute pyelonephritis from a renal infarct (which tends to spare the periphery; the so-called ' rim sign ') if imaged during the excretory phase, a  striated nephrogram  may also be visible

45. EMPHYSEMATOUS PYELONEPHRITIS Ultrasound may show an enlarged kidney with coarse echoes within renal parenchyma or collecting system dirty echogenic foci with  reverberation /ring-down artifacts representing gas ('dirty shadowing') may also be seen

46. CT is the best diagnostic modality for emphysematous pyelonephritis, and it may show the following diagnostic features: enlarged, destroyed renal parenchyma small bubbly or linear streaks of gas 1 fluid collections, with gas-fluid levels focal necrotic areas +/-  abscess

47. Acute diverticulitis Most common site – sigmoid and descending colon Presentation – LLQ pain , fever leucocytosis

48. Sonographic findings Segmental concentric thickening of the wall Echogenic foci within or beyond the wall Thickening of mesenteric Inflammation of pericolonic fat

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50. Bowel obstruction Types – mechanical functional . Dilation of GI tract proximal to obstruction . Hyperperistalsis . Accumulation of large quantities of fluid

51. Small bowel obstruction 80 percent of mechanical obstructions Presentation – cramping abdominal pain Abdominal distension Vomitings . Most common cause - adhesions

52. X ray erect abdomen Dilated small bowel loops ( more than 3 cm ) Air fluid levels Centrally dilated bowel loops

53. Sonographic findings Dilated bowel loops To and fro peristalsis or Whirling appearnce of intraluminal contents Dilated jenunal loops – valvulae conniventes Dilated ileal loops – characteristically characterless

54. Closed loop obstruction Bowel loops are occluded at two adjacent points Closed loop obstruction if associated with ischaemia is called as strangulation

55. Sonographic findings Little or no air in obstructed bowel loop Fluid filled dilated bowel loops C or U shaped bowel loop Collapsed adjacent bowel loops

56. Large bowel obstruction Presentation – crampy abdominal pain abdominal distension . Obstipation Most common cause – colorectal cancer

57. Radiological findings Colonic distension with gas Collapsed distal colon – little or no air fluid levels No air in rectum ISCHAEMIC – intramural gas ( pneumatosis coli ) portal venous gas . Free intraabdominal gas

58. Intussusception Telescoping of one segment of bowel into another segment Presentation – intermittent abdominal pain . Right upper quadrant mass . Red currant jelly like stool . Vomitings Most common in children due to hypertrophied lymphoid tissue.

59. Findings Fluoroscopy – coiled spring appearance. USG – target sign . Pseudokidney sign . Absent blood flow in intusussceptum . . Free fluid within intusussceptum

60. Bowel ischaemia USG findings – extraluminal free fluid ( tanga sign ) . Loss of peristalsis . Bowel wall thickening . Mural gas

61. Pneumoperitonuem Common cause – peptic ulcer disease Radiological findings – air under diaphragm . Rigler sign or double wall sign . Tell tale sign or triangle sign . Football sign . Inverted v sign

62. Sonographic findings – enhancement Of peritoneal Stripe . Discrete hyperechoeic foci representing gas bubbles

63. Abdominal aortic aneurysm ( ruptured) Focal dilatation of abdominal aorta measuring 50 percent greater than proximal segment or more than 3 cm Presentation – pain , hypotension,pulsatile abdominal mass Common site of rupture – retroperitoneal

64. Sonographic findings Focal dilatation of aorta Aortic mural defect Partially detached mobile layer of intramural thrombus Intraperitoneal free fluid Heterogenous collection within retroperitoneal space

65. Presentation – lower abdominal pain,nausea ,vomiting Usg is the initial imaging modality Features – more than 4 cm . Variable echogenecity . Ovarian edema . Free fluid in pelvis . Ovarian tenderness to transducer Ovarian torsion

66. Doppler findings Little or no ovarian venous flow Absent arterial flow Whirlpool sign Absent or reversed diastolic flow

67. Hemorrhagic cysts Due to hemorrhage into corpuslutuem Findings – lace like reticular echoes . Intracystic solid cyst . Fluid level

68. Pelvic inflammatory disease Spectrum of infection and inflammation of upper female genital tract Presentation – acute pelvic pain . Vaginal discharge , fever On examination – cervical motion tenderness

69. Sonographic findings Echogenic pelvic fat Fluid in cul de sac Fluid in endometrial cavity Increased ovarian volume Hydrosalpinx Pyosalpinx Increased Vadcularity around the tube

70. Ectopic gestation Implantation of fertilized ovum outside the uterine cavity Presentation (ruptured )- severe abdominal pain,hypotension,bleeding Most common type is tubal ectopic

71. Tubal ectopic Adnexal mass separate from ovary Tubal echogenic ring Colour Doppler – ring of fire sign Fluid in POD and hemoperitoneum

72. Meckels diverticulitis Tubular Blindending Non compressible Hypoechoeic structure

73. Mesenteric adenitis Most common in children and adolescents Presentation – RLQ or umblical region Findings – 3 or more tender nodes with short axis measuring more than 5 mm.

74. Cystitis Presentation – suprapubic pain . Frequency,dysuria . Fever , hematuria Sonographic findings – bladder mural hypertrophy intramural debris internal free floating echeos

75. Testicular torsion Torsion of testis over spermatic cord resulting in cutting of of blood supply. m/c/c – Bell clapper deformity m/c/presentation – acute testicular pain

76. Sonographic findings Increased size of testis Homogenous echotexture ( early stage ) Heterogenous echotexture ( after 24 hrs ) with few hypoecheic areas Whirlpool sign – lamelated mass with concentric layering cephalad to testis Reactive hydrocele Absence of blood flow

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