Figure 2.

Summation images of tissue trauma caused by (a) the 18G needle and (b) the 32G needle exemplified in Figure 1. Each summed image contains 10 segmented and subfield divided histology slides. Each image is divided into 3 areas, 2 lateral and 1 center area. The mean value of the subfields in the 2 lateral areas represents the baseline value of the tissue. The signal is found in the center area, where the signal threshold is defined as the baseline value plus 2 standard deviations. The number of subfields qualifying as signal subfields is defined as the signal count of the center area.