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Influence of Ultrasound System and Gain on Grayscale Median Values
Author(s) -
Steffel Catherine N.,
Brown Roger,
Korcarz Claudia E.,
Varghese Tomy,
Stein James H.,
Wilbrand Stephanie M.,
Dempsey Robert J.,
Mitchell Carol C.
Publication year - 2019
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.1002/jum.14690
Subject(s) - grayscale , gsm , intraclass correlation , medicine , imaging phantom , concordance , correlation coefficient , nuclear medicine , statistics , biomedical engineering , artificial intelligence , reproducibility , mathematics , computer science , telecommunications , image (mathematics)
Objectives The purpose of this study was to determine the reliability of grayscale median (GSM) measurements across different ultrasound (US) systems and effects of gain on GSM values. Methods Two vessels in a grayscale vascular phantom were imaged with 7 US systems at 3 gain settings. Two human participants were imaged at 3 gain settings. Each image was normalized, standardized, and segmented by expert and novice readers using grayscale analysis software. The concordance correlation coefficient (CCC) assessed agreement of GSM values for each system across gain settings and vessels and between readers. The intraclass correlation coefficient (ICC) assessed system‐level reader concordance across gain settings and vessels. A general linear mixed model for repeated measures was used to assess within‐ and between‐system mean GSM values. Results Grayscale median measurements performed on images from the same US system yielded excellent (CCC) (95% confidence intervals): 0.85 (0.75, 0.92) to 0.96 (0.92, 0.98). ICC per system were 0.94 to 0.98 for the expert reader and 0.85 to 0.95 for the novice reader. Gain adjustments above and below an optimal setting contributed to significantly different intrasystem GSM values on 4 of 7 systems in the near zone and 5 of 7 systems in the far zone ( P < .05). Intersystem GSM values differed on 5 of 7 systems ( P < .05). Images from the human participants showed differences in GSM values at optimum gain values ± 10 dB/%. Conclusions Grayscale median measurements are highly reproducible when obtained from the same US system with similar gain settings. Grayscale median values differ significantly across gain values and between systems. Researchers should consider the impact of US system and gain settings on GSM values when working to minimize system‐ and operator‐dependent factors.