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Choi Criteria for GIST Response

Choi criteria (Choi et al., 2007)

Evaluates gastrointestinal stromal tumor response to tyrosine-kinase inhibitors using both tumor size and CT attenuation, classifying the examination as CR, PR, SD or PD by the Choi criteria.

Also searched as: gastrointestinal stromal tumor · imatinib · Hounsfield · tumor density · tumor response

Baseline sum of longest diameters of target lesions

Summed longest diameters, using the same target-lesion selection rules as RECIST.

mm
Current sum of longest diameters of target lesions
mm
Baseline mean tumor attenuation

Mean attenuation of target lesions on contrast CT; both HU values are needed for the density criterion.

HU
Current mean tumor attenuation
HU
New lesion(s) present
New or enlarging intratumoral nodule(s)

A new enhancing nodule within a treated, hypodense mass - the classic "nodule within a mass" pattern of GIST relapse.

Obvious progression of non-measurable disease

Blocks a partial-response designation under the Choi definitions.

Information
Incomplete input
  • Please provide: baseline sum of longest diameters, current sum of longest diameters.

How this tool works

GISTs responding to imatinib often become hypodense and homogeneous long before they shrink, so the Choi criteria combine size with tumor density measured in Hounsfield units on contrast CT. Partial response is a fall of at least 10% in the sum of the longest diameters of target lesions OR a fall of at least 15% in mean tumor attenuation, with no new lesions and no obvious progression of non-measurable disease. Progressive disease is a size increase of at least 10% that is not rescued by a 15% density drop, the appearance of new lesions, or new or enlarging intratumoral nodules. Complete response requires disappearance of all lesions without new lesions. Density is measured in a representative region of each target lesion on a consistent contrast phase.

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