Diagnostic effectiveness of quantitative [18F]flutemetamol PET imaging for detection of fibrillar amyloid β using cortical biopsy histopathology as the standard of truth in subjects with idiopathic normal pressure hydrocephalus

Table 5 Definitions for diagnostic efficacy of [18F]flutemetamol PET

Metric	Definition
Sensitivity^a	TP/TP + FN
Specificity^a	TN/TN + FP
Accuracy^b	TP + TN/TP + FN + TN + FP
Positive predicative value (PPV)^a	TP/TP + FP
Negative predictive value (NPV)^a	TN/TN + FN

^aThe highest possible value of the result is 1. This result generally does not depend on disease prevalence.
^bThe highest possible accuracy is 1. Accuracy is a function of disease prevalence in the population being tested.

ISSN: 2051-5960