Virtual Histology of Colorectal Lesions Using Laser-Scanning Confocal Microscopy

Background and Study Aims: Histological examination of gastrointestinal lesions is currently based on light-microscopic examination of thin-slice specimens, with hematoxylin and eosin staining. A study of the use of laser-scanning confocal microscopy (LCM) to obtain immediate microscopic images of untreated specimens for examining colorectal lesions was carried out. A probe-type LCM prototype endomicroscope that can be passed through the working channel of an endoscope has also been developed.
Materials and Methods: The study materials consisted of colorectal lesions resected either endoscopically or surgically at Showa University Northern Yokohama Hospital. One hundred untreated specimens were examined using LCM. The histopathological findings in the lesions were seven cases of normal colonic mucosa, five hyperplastic polyps, 68 adenomas with low-grade dysplasia, 10 adenomas with high-grade dysplasia, and 10 adenocarcinomas. An argon laser beam with a wavelength of 488 nm was used for the LCM study. Observation of the resected normal colonic mucosa (in vitro) and the rectal mucosa of a healthy volunteer (in vivo) was possible using the endomicroscope. The LCM images for each specimen were compared with the hematoxylin-eosin-stained histopathological cross-sections.
Results: The LCM images corresponded well with the conventional hematoxylin-eosin light-microscopic images. The nuclei were not visualized in normal mucosa or hyperplastic polyps. In adenomas with high-grade dysplasia and carcinomas, nuclei were more often visible than in adenomas with low-grade dysplasia. The rate of visualization of nuclei was significantly different (P < 0.01) between these two groups (60.0 % vs. 10.3 %). In LCM images using endomicroscope, it was possible to recognize the orifices of the colonic glands and goblet cells both in vitro and in vivo.
Conclusions: Laser-scanning confocal microscopy provides immediate images that correspond well with those of hematoxylin-eosin staining. An improved probe-type LCM endomicroscope is being developed which should provide better histological images of colorectal lesions in vivo.

References

• 1 Cavanagh H D, Petroll W M, Jester J V. The application of confocal microscopy to the study of living systems.  Neurosci Biobehav Rev. 1993;  17 483-489
• 2 Corcuff P, Leveque J L. In vivo vision of the human skin with the tandem scanning microscope.  Dermatology. 1993;  186 50-54
• 3 Rajadhyaksha M, Grossman M, Esterowitz D. et al . In vivo confocal scanning laser microscopy of human skin: melanin provides strong contrast.  J Invest Dermatol. 1995;  104 946-952
• 4 Master B R. Scanning slit confocal microscopy of the in vivo cornea.  Opt Eng. 1995;  34 684-692
• 5 Gonzalez S, Rajadhyaksha M, Gonzalez-Serva A. et al . Confocal reflectance imaging of folliculitis in vivo: correlation with routine histology.  J Cutan Pathol. 1999;  26 201-205
• 6 Koenig F, Gonzalez S, White W M. et al . Near-infrared confocal laser scanning microscopy of bladder tissue in vivo.  Urology. 1999;  53 853-857
• 7 White W M, Tearney G J, Pilch B Z. et al . A novel, noninvasive imaging technique for intraoperative assessment of parathyroid glands: confocal reflectance microscopy.  Surgery. 2000;  128 1088-1100
• 8 Inoue H, Igari T, Nishikage T. et al . A novel method of virtual histopathology using laser-scanning confocal microscopy in-vitro with untreated fresh specimens from the gastrointestinal mucosa.  Endoscopy. 2000;  32 439-443
• 9 Inoue H, Cho J Y, Satodate H. et al . Development of virtual histology and virtual biopsy using laser-scanning confocal microscopy.  Scand J Gastroenterol Suppl. 2003;  237 37-39
• 10 Koenig F, Knittel J, Stepp H. Diagnosing cancer in vivo.  Science. 2001;  292 1401-1403
• 11 Kudo S. Endoscopic mucosal resection of flat and depressed types of early colorectal cancer.  Endoscopy. 1993;  25 455-461
• 12 Sakashita M, Aoyama N, Maekawa S. et al . Flat-elevated and depressed, subtypes of flat early colorectal cancers, should be distinguished by their pathological features.  Int J Colorectal Dis. 2000;  15 275-281
• 13 Kudo S, Hirota S, Nakajima T. et al . Colorectal tumours and pit pattern.  J Clin Pathol. 1994;  47 880-885
• 14 Kudo S, Tamura S, Nakajima T. et al . Diagnosis of colorectal tumorous lesions by magnifying endoscopy.  Gastrointest Endosc. 1996;  44 8-14
• 15 McLaren W, Anikijenko P, Barkla D. et al . In vivo detection of experimental ulcerative colitis in rats using fiberoptic confocal imaging (FOCI).  Dig Dis Sci. 2001;  46 2263-2276