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FIG 7. A, The nearest-neighbor generated enhancement volumes (cm3) are highly correlated (r2 = .99) with the manually defined standard. Though not able to duplicate the volumes as determined manually, the nearest-neighbor algorithm is systematic and accurate in its ability to quantify tumor volume based on contrast-enhancing tissue volumes.
B, The surface modeling algorithm generated enhancement volumes (cm3) are also highly correlated (r2 = .94) with the manually defined standard. It is unable to separate nonenhancing necrotic areas from surrounding enhancing areas and cannot generate volumes based on noncontiguous lesions. Therefore, the surface modeling algorithm has a tendency to overestimate and underestimate enhancement volumes to a greater degree than does the nearest-neighbor algorithm.
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