Impact of clinical information on diuretic renography scan interpretation

Objectives Our objective was to determine the impact of clinical information on diuretic renography scan interpretation to guide clinicians and facilitate incorporation of clinical information into an expert system to interpret renal scans.

Methods Baseline and furosemide MAG3 acquisitions of 92 patients with suspected obstruction were randomly selected from an archived database and independently interpreted by 3 experienced readers without clinical information and re-interpreted with access to a File Maker Pro database that included summaries of CT, US, MR, IVP, prior MAG3 scans, surgeries, stents and serum creatinine reports. All MAG3 studies included a camera-based MAG3 clearance and were processed with an in-house update of the QuantEM-TM software. Five patients had only one kidney. Readers scored each kidney on a scale from +1.0 to -1.0; scores > 0.21 represented obstruction with higher scores indicating greater confidence in the diagnosis of obstruction. Scores from +0.2 to -0.2 were equivocal and scores < -0.2 indicated non-obstructed kidneys. There was a subsequent consensus reading with and without clinical information where the 3 readers were allowed to change their scores; the mean score served as the final score.

Results Without clinical information, 46 kidneys were considered to be obstructed, 18 equivocal and 115 non-obstructed. Clinical information changed the category (obstructed, equivocal, non-obstructed) in only 4 of 179 (2.2%) of kidneys; for 3 of the 4 kidneys, the score was close to the equivocal cut points (0.2 and -0.2), and the degree of change was less than 0.1. The clinical history changed the score >0.1 in only 17 kidneys and changed the score change >0.2 in only 3 kidneys; for the vast majority of kidneys, the score was unchanged or minimally changed.

Conclusions Clinical information had little impact on diuretic renography scan interpretation when the scan included a camera-based MAG3 clearance as a measure of renal function.

Research Support NIBIB and NIDDK, R01-EB008838