Role of CT in acute pancreatitis

1
Role of CT in acute pancreatitis

• Which patient of acute pancreatitis needs CT ?
• What are the alternatives to CECT in renal
  dysfunction ?

• High resolution dynamic CECT
• Scan speed 1-2 S/Sec, thin slice (5mm)
• Dynamic scanning, large bolus contrast
• Arterial/venous phase
• Better visualization of non-perfused area

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Why CECT ?
Degree Necrosis Extent Infection
Aspiration/culture
Peripancreatic fluid collection its
content Pseudocyst wall maturity,
contents Pseudoaneurysm Bowel
involvement
Balthazar, Gastroenterology 1994 106 259 - 261
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Why identify pancreatic necrosis?
AIIMS (Jan 1997 Nov. 2000) N 205, (Death
20, 9.7)
Clinically severe pancreatitis (APACHE II gt8)
N72 (35) i CECT necrosis in 68/72
(94) i Death 18/72 (25)
Clinically mild/moderately severe
pancreatitis N123 (65) APACHE II lt 8 i CECT
necrosis 0/123 i Death 2/123 (1.5) (plt0.01)
18/20 (90) of those who died had ANP
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Why identify pancreatic necrosis?
37/68 (54.4) ANP Infected 12/37 (32.4)
infected necrosis died 6/31 (20) sterile
necrosis died
5
Correlation of extent of necrosis with organ
failure and mortality
Plt0.001
Plt0.002
Extent of necrosis
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Why identify pancreatic necrosis?

• Subject No. of Patients
• Edematous 992 71
• ANP 286 21
• Sterile 196/286 68
• Infected 90/286 32
• Panc. Abscess 36 3
• Pseudocyst 82 6
• Total 1396 100

Beger 1997 (May 1982 Dec 1995) World J Surg.
21 130 135
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Why identify pancreatic necrosis?

• ANP 205
• Factor Patient Mortality p
• ANP
• 30 79 (39) 6 ( 8)
• 50 75 (37) 18 (24) lt 0.0001
• gt 50 51 (25) 26 (51)
• Extrapancreatic Necrosis
• Present 96 (47) 33 (34) lt0.02
• Absent 109 (53) 17 (16)
• Pancreatic Ascites
• Present 115 (56) 42 (37) Absent 90 (44) 8
  (9) lt0.01
• Infected Necrosis
• Present 56 (41) 18 (32)
• Absent 82 (59) 8 (10) lt0.01

Beger, 1997
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CT Balthazars Scoring
Score
A. Normal 0 B. Pancreatic
enlargement 1 C. Peripancreatic
inflammation 2 D. 1 peripancreatic fluid
collection 3 E. gt1 peripancreatic fluid
collection 4 No necrosis 0 1/3rd
necrosis 2 1/2 necrosis 4 gt1/2 necrosis 6
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When should CECT be done?

• ANP gets established by 72 hours
• Within 48 hr 75 CT n88
• 96 hr - 88 CT No. CT. 255
• 7 d - 95 CT 3 CT/ Patient
• Atlanta 1992 40 pancreatologists all agreed
  that the best time for is CT 3rd to 7th day

(Balthazar Radiology 1990 174 331 336)
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Alternatives to CECT in renal insufficiency

• High risk for renal failure after contrast
• Diabetes mellitus upto 50
• Previous renal disease 30 90
• Drugsirenal perfusion (ACE inhibitors)
• Large volume contrast
• Use of furosemide/mannitol before using contrast

Precautions Hydration osmolality Assessment of
renal function / size Avoid nephrotoxic
drugs Use of nonionic contrast
Mechanism Release of free radicals, direct
toxicity on tubular epithelium, renal
hemodynamics
(Safirstein, NEJM 2000)
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Alternatives to CECT in renal insufficiency
Calcium channel antagonists, dopamine, ANP,
Endothelin receptor antagonists useless
Acetylcystine 600 mg bd (n-83, S.Crgt1.2mg or GFR
lt 50 ml/m)

• Free radical scavenger
• S.nitrosothiol
• i
• Vasodilation

Tepel et al NEJM 2000 343 180 4
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MRI Alternative to CECT in renal insufficiency

• Benefits
• Superior resolution
• No radiation
• Gadopentate dimeglumine (Gadolinium)
• Contrast CECT
• Volume required 10 ml
• T2 weighted images pick up gall stones

• Problems
• Sick patients with tubes
• Long time vs breath hold
• Availability
• Gas density vs Collection difficult to
  differentiate

Needs evaluation in a prospective study
Chalmers, Eur. J Gastroenterol Hepatol 1997
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Summary

• CT is necessary if diagnosis is in doubt.
• CECT is necessary to identify ANP between 3rd to
  7th day of onset of AP
• ANPs clinical counter part is clinical/biochemica
  l severity of the disease objective assessment
  should be done by APACHE II (gt8) or Ransons
  criteria (gt3)
• Other clinical pointers of ANP - no improvement
  in 72 hr - organ failure
• - fever, leucocytosis
• Initial improvement followed by deterioration
• In presence of RF Acetylcystine CECT or MRI
  using Gadolinium may be done