Table 1.

Grading scale for subjective image quality evaluation.

Parameters	5	4	3	2	1
Noise	Minimal or no noise	No significant noise	Noisy diagnostic	Significant noise (affects diagnosis)	High-level noise (nondiagnostic)
Sharpness	Excellent sharpness	Good sharpness	Moderate sharpness	Poor sharpness (bad visibility)	Zero visibility (nondiagnostic)
Contrast	Excellent contrast	Very good contrast	Good contrast	Poor contrast (unsatisfactory visualization)	Image similar to use of no contrast (nondiagnostic)
Diagnostic confidence	Completely confidence	High confidence	Good confidence	Poor confidence	No diagnostic confidence (unacceptable)
Artefacts	No artefacts	Insignificant artefacts	Minor artefacts	Major artefacts (diagnosis still possible)	Artefacts affecting diagnostic information
Blotchy appearance	Absent	Mild	Moderate	Significant (diagnosis still possible)	Intense (affecting diagnosis)