<prompt> Which of the following is a gold standard investigation for diagnosis of renal stone?USGHelical CT with Non - contrastHelical CT with contrastMRI  <response>: USG is the IOC for gall stones and not renal stones. Helical CT without contrast is the IOC for all type of renal stones Helical CT with contrast is not preferred for looking calcifications like renal stones MRI is not preferred for renal stones 