
186 Handbook of Biomedical Optics
Figure 9.5 compares BWI values from malignant
(BWI = 1.96 ± 0.3) and normal tissues (BWI = 2.77 ± 0.47) mea-
sured in 18 subjects. Malignant tumors had signicantly lower
BWI than normal tissues (p < 0.0001), suggesting that tumors
appear to have more free than bound water. e relationship
between bulk water concentration and BWI of normal and
malignant tissues was also studied. In general, BWI is inversely
proportional to tissue water content. In normal tissues, the water
content range is relatively narrow (10%–28%), and the BWI spans
between 2.3 and 4.3. However, in cancer tissues, t