(a) Pulmonary fibrosis in the course of interstitial lung disease: down arrows—pleural line; left arrows—B line artifact observed at 2 MHz frequency. (b) Pulmonary fibrosis in the course of interstitial lung disease: down arrows—pleural line; left arrows—vertical artifacts observed at 6 MHz frequency. The image was obtained from the same patient and identical assessment site as in Figure 4a. (c) Cardiac edema: down arrows—pleural line; left arrows—B-line artifacts observed at 2 MHz frequency. (d) Cardiac edema: down arrows—pleural line; left arrows—B-line artifacts observed at 6 MHz frequency. The image was obtained from the same patient and identical assessment site as in Figure 4c.