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European Radiology Experimental

Table 2 Simulated PI-RADS diagnoses by cut-off selection

From: An information-oriented paradigm in evaluating accuracy and agreement in radiology

  

Target biopsy

 

Positive

Negative

Magnetic resonance imaging

Positive (PI-RADS category ≥ 3)

380

300

Positive predictive value 55.8% (380/680)

Negative (PI-RADS category ≤ 2)

20

300

Negative predictive value 93.7% (300/320)

  

Sensitivity 95% (380/400)

Specificity 50% (300/600)

 
  

Cohen κ

0.403

 
  

Information ratio

0.195

 
  1. By arbitrary setting the cutoff to PI-RADS category 3 (i.e., categories below 3 are considered a negative response, categories above 2 correspond to a positive response), we obtain Table 2, showing a sensitivity of 0.95 (95%) and a specificity of 0.50 (50%). It follows that the information ratio of the scenario is about 0.195, while for the same data Cohen κ equals 0.403
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