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Modified CTSI

Modified CT Severity Index for Acute Pancreatitis

Combines the Balthazar CT grade (pancreatic inflammation), percentage necrosis, and extra-pancreatic complications into a 10-point score. Performed on CT at 72–96 hours from symptom onset.

PancreatitisRadiologyGeneral Surgery
Modified CTSI Calculator
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Scoring Components

ComponentFindingPoints
Pancreatic inflammatory processNormal (Grade A)0
Focal/diffuse enlargement; intrinsic changes (Grade B/C)2
Acute fluid collection; gas in/around pancreas (Grade D/E)4
Pancreatic necrosis (% of gland)None0
≤ 30%2
> 30%4
Extra-pancreatic complicationsAbsent0
Present (any)2

Total MCTSI range: 0–10. CT should be performed at 72–96 hours from symptom onset to allow necrosis to declare — CT in the first 48 hours underestimates necrosis extent.

Interpretation

MCTSISeverityMorbidityMortality
0–2Mild~5%~0%
4–6Moderate~35–54%~4%
8–10Severe~92%~17%

Clinical Application

  • Timing: CT at 72–96 hours is the standard — earlier CT is warranted only if clinical deterioration or diagnostic uncertainty about a surgical emergency (e.g., bowel perforation).
  • MCTSI 0–2: Interstitial oedematous pancreatitis; typically no necrosis; usually self-limiting.
  • MCTSI 4–6: Moderate severity; may have limited necrosis. Follow-up CT at 1–2 weeks if not improving clinically.
  • MCTSI ≥8: Extensive necrosis (≥30%) or multiple extra-pancreatic complications. High risk of pancreatic infection, multi-organ failure. Management in specialist HPB centre. Step-up approach (percutaneous/endoscopic drainage → minimally invasive necrosectomy → open surgery) for infected necrotising pancreatitis.
  • The original Balthazar CTSI (without extra-pancreatic complications) is still used in many centres — MCTSI is preferred as it adds independent prognostic information.

References

  1. Balthazar EJ, et al. Acute pancreatitis: value of CT in establishing prognosis. Radiology. 1990;174(2):331–336.
  2. Mortele KJ, et al. A modified CT severity index for evaluating acute pancreatitis. AJR. 2004;183(5):1261–1265.
  3. Banks PA, et al. Classification of acute pancreatitis — 2012: revision of the Atlanta classification. Gut. 2013;62(1):102–111.
  4. Working Group IAP/APA. IAP/APA evidence-based guidelines for the management of acute pancreatitis. Pancreatology. 2013;13(4 Suppl 2):e1–15.

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