Balthazar CT Severity Index Calculator

What is the Balthazar CT Severity Index?

The Balthazar CT Severity Index, also called the classic CT Severity Index or CTSI, is an imaging-based score used to grade the severity of acute pancreatitis on CT.

It combines two components: the Balthazar CT grade, which reflects pancreatic and peripancreatic inflammatory changes, and the pancreatic necrosis score, which reflects the extent of necrosis.

How is the score calculated?

The classic CTSI is calculated on a 10-point scale by adding Balthazar CT grade points from 0 to 4 and pancreatic necrosis points from 0 to 6.

A higher CTSI score is associated with more severe imaging findings and a higher risk of adverse clinical outcomes, but the score should not replace clinical judgment.

Balthazar CTSI interpretation

Balthazar CT grade components

• Grade A: normal pancreas, 0 points.
• Grade B: focal or diffuse pancreatic enlargement, 1 point.
• Grade C: pancreatic inflammation with peripancreatic fat changes, 2 points.
• Grade D: single peripancreatic fluid collection, 3 points.
• Grade E: two or more peripancreatic collections or gas in/adjacent to the pancreas, 4 points.

Important limitations

Balthazar CTSI is useful for imaging severity assessment, but it is not a standalone management tool.

• It requires appropriate CT assessment, and necrosis is best evaluated with contrast-enhanced CT when clinically indicated.
• It does not directly include persistent organ failure, systemic inflammatory response or full clinical severity criteria.
• Early CT may underestimate severity because pancreatic necrosis can evolve over time.
• A fixed mortality percentage is not shown because mortality depends on organ failure, infection, comorbidities, timing and treatment quality.
• Do not confuse this classic Balthazar CTSI with the Modified CT Severity Index by Mortele, which uses a different structure and includes extrapancreatic complications.