Biomedical Engineering Reference
In-Depth Information
FIgurE 14.17
Ex vivo
SHG/THG images of the freshly excised SSM specimen obtained in the (a)-(d) darker
brownish region and (e)-(h) lighter brownish region at different depths beneath the skin surface. (a)-(d) Throughout
the first 100-μm layer in the darker region, THG-bright melanoma cells (arrows in (a)) with varied shapes and
larger nuclei were irregularly distributed to replace the normal keratinocytes and (d) no collagenous structure can
be observed due to increased thickness of epidermis and limited penetrability. (e)-(h) In the lighter region, (e) no
melanoma cells but some sparsely distributed grainy particles (arrows) with a stronger THG contrast were found
in the stratum granulosum. (f) A few dendritic and THG-bright melanoma cells (arrows) were found within the
keratinocytes. (g) In the stratum basale, THG-bright cells were found without uniform brightness and distinct
cell borders, while the honeycomb morphology was disrupted. (h) Owing to milder invasion in this region, the
collagenous structures of the papillary dermis and the capillary (arrow) were observed. (i)-(l)
Ex vivo
SHG/THG
images of the freshly excised normal skin removed from the same patient, obtained at (i) stratum granulosum; (j)
dermo-epidermal junction; (k) papillary dermis; and (l) reticular dermis. SHG images corresponding to (h) and (j)
are shown in (h-S) and (j-S), respectively. Scale bar: 50 μm.
melanoma cells occupying this layer are shown by THG modality with strong THG intensity (arrows
in Figure 14.17a). Through the THG signals, the larger nuclear diameter and varied cell shapes of the
superficially spreading melanoma cells can be clearly revealed as diagnostic characteristics. Owing to
a more severe invasion of the melanoma cells in the darker region, throughout the first 100 μm layer
(Figures 14.17a through 14.17d), the regular keratinocytes are replaced by single or clustered melanoma
cells and the honeycomb architectures of the normal epidermis (Figures 14.17i and 14.17j) are almost
thoroughly destroyed. On the other hand, in the lighter region, only sparsely distributed grainy par-
ticles with strong THG contrast can be found to accumulate around the nuclei of the granular cells
(arrows in Figure 14.17e), and most of the regular patterns of the granular cells are preserved. Owing to a
less severe invasion of melanoma cells within this lighter region, in the shallower layers of the epidermis,
only a few melanoma cells (arrows in Figure 14.17f) can be found and parts of the honeycomb architec-
tures of the epidermis can still be observed. When moving the imaging plane into the stratum basale
(Figure 14.17g), the THG-revealed cells in this layer show loss of distinct cell borders and appear more
spindle-like, different from the basal cells with clearly defined cell borders and uniform THG bright-
ness observed in the normal skin (Figure 14.17j). Notice that in the case of SSM, the regions with SHG
contrasts are often beyond the penetrability. Since only the SHG modality is not sufficient for diagnosis,
