Studies on healthy and neoplastic tissues using positron annihilation lifetime spectroscopy and focused histopathological imaging

Abstract

Samples of healthy and neoplastic myometrial tissues were investigated using Positron Annihilation Lifetime Spectroscopy (PALS). Meaningful differences between normal and diseased tissues were observed for each patient. The differences were also clearly visible for various kinds of lesions in each patient. The set of lifetimes and intensities obtained from PALS was correlated with the histopathological examinations of the same fragments of tissues. Strong coincidence between PALS parameters and histopathological findings was observed only in the case of a very precise correlation of the investigated area in both techniques. Measurements and discussion presented here were carried out to develop a method for measuring the sub-nanometric structure of human tissues. This kind of investigation, using positron probe, creates an opportunity of a new application in Positron Emission Tomography (PET).

Figure 1

The place of sampling in the organ immediately after removal from the body to allow proper histopathological evaluation of tissues adjacent to the examined site.

Figure 2

Schematic presentation of the e+ range in the sample. In the central part there is ²²Na salt (flat dot, yellow), from which e+ are emitted in all directions. The positron's penetration area is marked: 90% of positrons is stopped at maximal distance of 1.1 mm from the source (orange area), and 99.9%—at 2,7 mm (blue area).

Figure 3

Handling of the samples: (a) measuring chamber with the two sub-sample placed there by the surgeon separated by a polycarbonate plate with a visible hole for placing the source, the direction of plate movement is indicated by an arrow, (b) the ²²Na source in the Kapton foil and Teflon frame, (c) biological sample immobilized on a cork base, (d) sample placed in formalin.

Figure 4

Scheme of embedding the sub-sample into a paraffin block.

Figure 5

(a) Glass slide with section of sub-sample stained with H&E and midpoint of the slide marked with a black marker; (b) high grade serous carcinoma (H&E, 200 ×); (c) adipose tissue (H&E, 200 ×); (d) leiomyoma with fibrous connective tissue bands (H&E, 200 ×); (e) thick-walled arterial vessel (H&E, 200 ×); (f) leiomyoma with thin-walled venous vessel (H&E, 200 ×).

Figure 6

The intensities and lifetimes of mixed p-Ps and free e+ annihilation component (I₁, τ₁), free e+ component (I₂, τ₂) and o-Ps component (I₃, τ₃) in investigated samples. Red dots—results obtained using the PALS technique for the samples described in Table 1, dotted horizontal lines show examples of results obtained for samples from patients not described in this work, green line—the endometrium, blue line—ovarian sample.