Calculate the original 1990 CTSI only: preserve both components, their points and the exact 0-10 total. Keep modified CTSI and Revised Atlanta severity explicitly separate.
{
"applicability": {
"use_for": "Prognostic CT severity assessment in acute pancreatitis when contrast-enhanced CT adequately depicts pancreatic enhancement and local inflammatory findings.",
"required_inputs": [
"Balthazar_morphologic_grade_A_to_E",
"percentage_of_nonenhancing_pancreatic_parenchyma"
],
"necrosis_definition": "Lack of enhancement of part or all of the pancreatic gland on contrast-enhanced CT."
},
"feature_groups": [
{
"id": "balthazar_morphologic_grade",
"choose_one": true,
"options": [
{
"outcome_code": "A",
"finding": "normal_pancreas",
"points": 0
},
{
"outcome_code": "B",
"finding": "focal_or_diffuse_pancreatic_enlargement",
"points": 1
},
{
"outcome_code": "C",
"finding": "intrinsic_pancreatic_abnormality_with_peripancreatic_inflammation",
"points": 2
},
{
"outcome_code": "D",
"finding": "single_ill_defined_peripancreatic_fluid_collection_or_phlegmon",
"points": 3
},
{
"outcome_code": "E",
"finding": "two_or_more_peripancreatic_collections_or_gas_in_or_adjacent_to_pancreas",
"points": 4
}
]
},
{
"id": "pancreatic_necrosis",
"choose_one": true,
"options": [
{
"outcome_code": "N0",
"extent": "none",
"points": 0
},
{
"outcome_code": "N<30",
"extent": ">0_and_<30_percent",
"points": 2
},
{
"outcome_code": "N30-50",
"extent": "30_to_50_percent_inclusive",
"points": 4
},
{
"outcome_code": "N>50",
"extent": ">50_percent",
"points": 6
}
]
}
],
"calculation": "Original CTSI = Balthazar morphologic points (0-4) + pancreatic necrosis points (0, 2, 4 or 6); valid total range 0-10.",
"score_map": [
{
"total": "0-3",
"outcome_code": "CTSI-0-3",
"interpretation": "lower CT severity band"
},
{
"total": "4-6",
"outcome_code": "CTSI-4-6",
"interpretation": "intermediate CT severity band"
},
{
"total": "7-10",
"outcome_code": "CTSI-7-10",
"interpretation": "high CT severity band"
}
],
"reporting_requirements": [
"report_Balthazar_grade_and_points",
"report_necrosis_percentage_category_and_points",
"report_exact_CTSI_total_0_to_10",
"describe_collections_and_gas_using_current_morphologic_terminology"
],
"do_not_conflate": {
"modified_CTSI": "The modified CTSI uses a different inflammatory component, only 0/2/4 necrosis points, and adds extrapancreatic complications; do not apply those rules here.",
"revised_Atlanta_severity": "Mild, moderately severe and severe acute pancreatitis in the Revised Atlanta classification are based chiefly on organ failure and complications, not these CTSI numeric bands."
},
"limitations": [
"CTSI is a prognostic imaging index, not a standalone diagnosis or treatment algorithm.",
"Necrosis can evolve and may be underestimated on an early examination; retain examination timing and adequacy of enhancement."
],
"source_locator": "Balthazar et al., Radiology 1990;174:331-336, PMID 2296641, original CTSI method and abstract; Balthazar, Radiology 2002;223:603-613, PMID 12034923, clinical/CT context; Revised Atlanta consensus, Gut 2013;62:102-111, DOI 10.1136/gutjnl-2012-302779, for the distinct current clinical severity definitions."
}