Renex Introduction

RENEX is a heuristic (rule based) decision support system that uses quantitative data derived from the renogram to provide a score that indicates if a kidney is obstructed, indeterminate, or not obstructed [1-4].   RENEX generates its score based on 60 rules that are fired depending on the input from the renogram; RENEX displays the most impactful rules (rationale) supporting its interpretation.

RENEX uses a numerical scoring system that converts a clinical diagnosis (obstructed, indeterminate, or not obstructed) to quantitative value [1]. The scoring system also expresses the level of confidence in the interpretation.  For purposes of this website, the more complex original scoring system has been reformatted as a 1-10 scale.

DIAGNOSIS SCORE
Not obstructed with very high confidence 1
Not obstructed with high confidence 2
Not obstructed with moderate confidence 3
Not obstructed with low confidence 4
Indeterminate, possibly not obstructed 5
Indeterminate, possibly obstructed 6
Obstructed, low confidence 7
Obstructed, moderate confidence 8
Obstructed, high confidence 9
Obstructed, very high confidence 10


You may want to apply this scoring system to the example on the Image and Parameters page; the RENEX scores for this example are provided at the conclusion of the final paragraph.

Additional Background: RENEX has a diagnostic accuracy similar to that of experts and a significantly greater diagnostic accuracy than nuclear medicine resident physicians with a full year of training [2, 5, 6].  When these experienced nuclear medicine residents were given access to the scores and rationale provided by RENEX and were asked to reinterpret the studies, their diagnostic accuracy significantly improved [5]. A follow up study with a different group of experienced residents showed the same results; the diagnostic accuracy improved when residents were given access to RENEX. Moreover, compared to their baseline level, training by RENEX resulted in greater diagnostic accuracy when the second group interpreted a new set of studies [6].

For the study shown on the Image and Parameters Page, RENEX interpreted the left kidney as “not obstructed” with a score of 1 and interpreted the right kidney as “not obstructed” with a score of 1.

  1. Garcia EV, Taylor A, Halkar R, Folks R, Krishnan M, Cooke CD, Dubovsky E.  RENEX: An expert system for the interpretation of 99m Tc- MAG3 scans to detect renal obstruction.  J Nucl Med 2006; 47:320-329  Link to article

  2. Taylor A, Garcia EV, Binongo JNG, Manatunga A, Halkar R, Folks R, Dubovsky EV.  Diagnostic performance of an expert system for interpretation of Tc-99m MAG3 scans in suspected obstruction.  J Nucl Med 2008; 49:216-224  Link to article

  3. Taylor AT, Garcia EV.  Computer-assisted diagnosis in renal nuclear medicine: Rationale, methodology and interpretative criteria for diuretic renography.  Semin Nucl Med 2014;44:146-158.  Link to article

  4. Garcia EV, Taylor A, Manatunga D, Folks R. A software engine to justify the conclusions of an expert system for detecting renal obstruction on Tc- 99m MAG3 scans.  J Nucl Med 2007; 48:463-470.  Link to article

  5. Taylor AT, Rahman AF, Folks RD, et al. Computer assisted interpretation of Tc-99m mercaptoacetyltriglycine diuretic scintigraphy enhances resident performance.  Nuclear Medicine Communications. 2023:44:427-433.  Link to article

  6. Taylor A, Rahman AKM, Folks R, et al.  Can RENEX, a decision support system for Tc-99m MAG3 diuretic renography, teach residents better diagnostic skills? (abstract) J Nucl Med. 2016: 57:540. Link Link to article