It is known that thermal challenge by cooling the hands is often used in thermographic tests in order to enhance the signal from pathological region (by decreasing the temperature of the surrounding periferal tissues). Does somebody knows if the environmental temperature affects the response to this kind of thermal challenge? I mean if a response will be stronger just at lower temperatures (ussually used in thermographic tests)?

I don't know if this is exactly what you're looking for, but here are a few references:

 

• L. Janský et al., Pflugers Arch (1996) 432(3):368-72 ("Changes in thermal homeostasis in humans due to repeated cold water immersions");
  
• A.Y. Gracey et al., Proc Natl Acad Sci USA (2004) 101(48):16970-75;
  
• A. Tanaka et al., Dig Dis Sci (2007) 52(2):478-87;
  
• J.M. Stocks et al., Aviat Space Environ Med (2004) 75(5):444-57.
  

Found these through a quick search on PubMed. The links will take you to the abstracts.