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FIGURE 6. Mechanisms for attenuation artifacts using resting attenuation scan. Red lines show positions of heart, mediastinum, and diaphragm during data acquisition; dashed red lines indicate mediastinum and diaphragm during standing and on first assuming supine position (left red dashed lines) and later in supine position after abdominal content shift cephalad (right red dashed lines). Black lines show positions of those structures not being imaged during attenuation or emission data acquisition of structures in red. Attn = attenuation; Dipy = dipyridamole.
