Acute onset flank pain. Suspected stone disease

CT usually best. Virtually all stones visualized on CT. IV contrast not usually needed unless seraching for abscess. Alternate diagnosis can be found. Exception would be young children and prenant women for which ultrasound would be better first line.

MRI can detect hydronephrosis, but not good at visualizing stones. Abdominal xray not sensitive enough, although has a place if following a known stone to see if it has passed. IVP can be useful, but usually not first line (urologists may order)