Do you avoid low-dose radiation CT stone scans in obese patients with recurrent nephrolithiasis given concerns for inadequate stone detection?  

Typically not. In order to know if your prevention program is working to prevent new stone formation and/or enlargement of existing stones, stone imaging is imperative. Options are basically limited to low-dose CT or ultrasound. Unless there are concerns about a possible pregnancy or insurance cover...

Given about 55% sensitivity of US, I am fine with the reduced sensitivity of low dose CT in obese patients. It is better than the alternative. I do not know off hand if trials have estimated the loss of counting accuracy in the obese, and I suspect it will depend a lot on details of patient selectio...