A quantitative method for measuring labeled compounds with whole-body autoradiography in tissue sections

Whole-body autoradiography is an effective method for localizing labeled compounds in various organs. However, the technique is limited in its ability to quantify such material.

Using tissue sections, this study investigated certain parameters involved in the quantitative estimation of labeled compounds by whole-body autoradiography. These included correlation between thickness of the section and radioactivity counted, the precision of such measurements, and the reproducibility of the autoradiographic films as tested by image analysis transmission. The precision of radioactivity measurements using tapes with a tissue section or a “punch biopsy” (punching off a piece of tissue from the section) was compared.

The results revealed excellent linearity between the thickness of the section and the radioactivity counted (r = 0.97) when section thickness was 10–30 μm. The measurement precision using tapes was better than with the “punch specimen” method. The reproducibility of photographic films was good when transmission was measured by image analysis.

It was concluded that a thickness of 30 μm is ideal for use in whole-body autoradiographic studies. It appeared that radioactivity measurement of tissue sections on tapes was superior to direct measurement from organs. Image analysis was employed and statistically evaluated for the first time in this study, and the promising findings suggest that it is likely to become the method of choice for future studies of this type.