Fig 1. Calculation processes of the three types of ASM image.
(A) ASM/A is an image indicated by the absolute difference between two ADC values, ADCb and ADCm, divided by ADCb ≤ five times. (B) PASM/A is an image indicated by the positive values of the difference between the two ADC values, which is deduced by subtracting ADCb from ADCm, divided by the ADCb value ≤ five times. (C) ASM/S is an image indicated by the absolute difference between the ADC values, ADCb and ADCm, divided by the SD image. ADC, apparent diffusion coefficient; ASM, ADC subtraction method, ADCb, ADC basic; ADCm, ADC modify; PASM/A, positive ASM; SD, standard deviation; S, SD image.