Terahertz Pulse Imaging of ex vivo Basal Cell Carcinoma

Abstract

Terahertz pulse imaging has been used for the first time to study basal cell carcinoma ex vivo, the most common form of skin cancer. This noninvasive technique uses part of the electromagnetic spectrum in the frequency range 0.1-2.7 THz. A total of 21 samples were imaged; the study was performed blind and results were compared to histology. Each image consisted of possible diseased tissue and normal tissue from the same patient. The diseased tissue showed an increase in absorption compared to normal tissue, which is attributed to either an increase in the interstitial water within the diseased tissue or a change in the vibrational modes of water molecules with other functional groups. Seventeen of the images showed a significant difference between the normal and the diseased tissue. These were confirmed by histology to be basal cell carcinomas. Of the remaining four cases, three showed no contrast and were confirmed as blind controls of normal tissue; the fourth case was a suspected basal cell carcinoma but showed no contrast, and histology showed no tumor. Cross-sections of the terahertz images, showing the terahertz absorption, were compared to histology. Regions of increased terahertz absorption agreed well with the location of the tumor sites. Resolutions at 1 THz of 350 microm laterally and 40 microm axially in skin were attainable with our system. These results demonstrate the ability of terahertz pulse imaging to distinguish basal cell carcinoma from normal tissue, and this macroscopic technique may, in the future, help plan surgery.

Terahertz-Wave Spectroscopy for Precise Histopathological Imaging of Tumor and Non-tumor Lesions in Paraffin Sections

“…These results indicate that histopathological diagnosis using optical microscopy may be replaced by THz images in the future. Previous reports indicate that, especially in basal cell carcinoma, different kinds of tissues are clearly distinguishable in THz images due to THz transmittance variation (Knobloch et al 2002;Woodward et al 2002aWoodward et al , 2002bWoodward et al , 2003Wallace et al 2004a). Recently, Fitzgerald et al (2006) reported the possibility of breast cancer diagnosis using THz images with a fresh, nonfixed tissue specimen as well as a paraffin specimen.…”

“…These tendencies are also applicable to normal myocardial tissue, necrotic or degenerated lesions, and scar lesions in which collagen fibers are dominant. There have been several reports of a clear contrast in THz images between cancer and normal tissues (Knobloch et al 2002;Woodward et al 2002aWoodward et al , 2002bWoodward et al , 2003. As important factors that influence the absorbance of THz waves in basal cell carcinoma (BCC), Woodward et al described the roles of water contained in tissues and the difference of cell density between the tumor and normal regions in the skin (Woodward et al 2002a(Woodward et al , 2002b(Woodward et al , 2003.…”

“…There have been several reports of a clear contrast in THz images between cancer and normal tissues (Knobloch et al 2002;Woodward et al 2002aWoodward et al , 2002bWoodward et al , 2003. As important factors that influence the absorbance of THz waves in basal cell carcinoma (BCC), Woodward et al described the roles of water contained in tissues and the difference of cell density between the tumor and normal regions in the skin (Woodward et al 2002a(Woodward et al , 2002b(Woodward et al , 2003. The effect of water in non-fixed fresh cancer tissue specimens has previously been examined, and no large effects of water on images were evidenced (Woodward et al 2003;Wallace et al 2004a).…”

“…As important factors that influence the absorbance of THz waves in basal cell carcinoma (BCC), Woodward et al described the roles of water contained in tissues and the difference of cell density between the tumor and normal regions in the skin (Woodward et al 2002a(Woodward et al , 2002b(Woodward et al , 2003. The effect of water in non-fixed fresh cancer tissue specimens has previously been examined, and no large effects of water on images were evidenced (Woodward et al 2003;Wallace et al 2004a). Furthermore, tissue specimens used in the present study were all dehydrated after fixation, therefore the influence of water was completely negligible.…”

“…Use in imaging for histopathological diagnosis has been reported since the latter half of the 1990s. Contrast images associated with different degrees of absorption or reflection of THz waves have been obtained for normal tissues, such as muscles, fatty tissue and cartilage, as well as for cancer tissue (Arnone et al 1999;Knobloch et al 2002;Woodward et al 2002aWoodward et al , 2002bWoodward et al , 2003Wallace et al 2004a;Nishizawa et al 2005;Fitzgerald et al 2006;Nakajima et al 2007).…”