Chest roentgenographic techniques for demonstrating human lung tumour xenografts in nude rats

Abstract

SummaryRoentgenographic techniques were investigated for imaging orthotopic lung tumours in anaesthetized nude rats endobronchially implanted with human lung cancer cells. A conventional radiographic unit with a dual-screen, double-emulsion film mammographic receptor produced images preferable to those from a mammographic unit because of superior resolution. Typical exposure factors were 300 rnA, 29 kVp, and 17 ms at a focus-film distance of 76 em with a 2·11 by 2·41 mm effective focal spot and inherent filtration of 1· 2 mm aluminium. Sensitivity for tumour detection was 0,93 for S9 animals with pathologically proved tumours and 0·96 for S4 animals with tumours larger than 4 mm or 50 mg. For 24 pathologically tumour-free animals, specificity was 1·00. For 55 animals radiographically judged to have tumours, positive predictive value was 1·00. For all 83 animals, accuracy was 0·95. This technique effectively demonstrates orthotopic human lung tumours in nude rats and should be useful for noninvasive monitoring of tumour presence, location, size, and changes in size. al., 1985;McLemore et al., 1987;Naito et al., 1987; Cornil et (cl., 1989) has stimulated interest in model tumour; whose size cannot be monitored noninvasively with calipers. The approach to this monitoring prohlem taken by McLemore et al. , was to image or1hotopic human lung tumours in their nude mouse model with a human mammographic unit.McLemore's nude mouse model, useful for comparative modelling studies, has limitations because of the small size of mice. We, therefore, applied his technique to Rowett nude rats (Howard et al., 1989;1991). The larger size of this new model facilitates: (1) surgery and blood sampling; (2) growth of large (> 500 mg) orthotopic tumours without causing animal death; and (3) ex vivo perfusion of the tumour-bearing lungs (Howard et al., 1990). Because of these advantages, the rat model is particularly suitable for biological and r'reclinical studies of lung cancer.Like McLemore, we found it necessary in our new model to noninvasively determine tumour take-rates, locations, sizes, and changes in size.

Refinement of an Orthotopic Lung Cancer Model in the Nude Rat

“…7,16 Several investigators have created orthotopic pulmonary xenografts by instilling tumor cells into the upper airways of SCID mice, nude mice, or nude rats. 12,13,17,23,24,37 However, many have relied on surgical exteriorization of the trachea for placement of cannulas and instillation of cells. Depending on the cell type, the tumors that develop from surgical instillation are often localized to a single lung lobe.…”

Laboratory Models of Lung Cancer

“…Tumor size and tumor weight or volume changes are simple and easily reproducible parameters in subcutaneous xenograft models, but are more difficult, except at necropsy, in most orthotopic models. We used a mammographic imaging technique to assess both primary tumor growth and metastases in our orthotopic model [117]. Miniaturized human imaging methods, such as computed tomography, magnetic resonance imaging, and positron emission tomography, are now available for laboratory use.…”