Table 3.

Parameters for the Spectral Analysis Used for the Estimations of Attenuation Coefficient Slope versus Frequency and BSC

	UltraSonix	VisualSonics	Siemens
Spectral window size (axial  × lateral)	4 mm × 10 mm for αo	2 mm × 5 mm for αo	3-5 mm × 5 mm
	3.8 mm × 3.8 mm for  BSC	1.5 mm × 1.5 mm for BSC
Tapering function	Rect for αo	Rect for αo	Hann window
	Hann for BSC	Hann for BSC
Spectral window overlap  ratio (axial × lateral)	50% × 50% for αo	50% × 50% for αo	75% × 75%
	75% × 75% for BSC	75% × 75% for BSC
Attenuation estimation  distance	10 mm	5 mm	6-8 mm
Attenuation estimation  distance overlap ratio	50%	50%	0-85%
Signal processing bandwidth	4-8 MHz (Layer 1)	7.2-12.2 MHz (Layer 1)	4-10 MHz (Layer 1)
	3.6-6.5 MHz (Layer 2)	8.5-13 MHz (Layer 2)	4-8 or 3-8.5 MHz  (Layer 2)
	3.3-6 MHz (Layer 3)	9.1-14.7 MHz (Layer 3)	4-6 or 3-7 MHz (Layer 3)
Bandwidth selection  criterion	−6 dB	−6 dB	5-10 dB above noise  floor

BSC = backscatter coefficient. “Rect” and “Hann” refer to the rectangular and Hann time-gating functions, respectively,