<prompt> Best investigation for acute cholecystitis isERCPOral cholecystography OCGHIDA scanIV cholangiography  <response>: C i.e. HIDA Scan HIDA Scan PIPIDA are best test to rule out acute cholecystitisQ with.--400 negative predictive value. It can be pseudo positive in chronic malnutrition, Parenteral nutrition alcoholic liver disease. 