Abstract
1772
Objectives In dynamic renography with 99mTc-MAG3, split renal function (SLF) is usually calculated using the area under the renogram 60 - 120 seconds after injection (Area method) [1]. An alternative approach is using the maximum slope of the upslope phase of the renogram (Slope method). We compared both methods against static scintigraphy with 99mTc-DMSA in the same patients.
Methods We retrospectively identified all patients that had undergone dynamic MAG3 (0 - 36 min post injection; p.i.) and static DMSA scintigraphy (4 h p.i.) within 10 days between Jan 2006 and Dec 2014 in our PACS. Digital acquisitions were processed with Segami Oasis 1.9.3 (Segami Corp., Maryland/MD) using area and slope algorithms, respectively. For the purpose of this analysis, SLF was quantified only on posterior projections with bilateral semilunar regions for background correction. For each patient, the poorer functioning kidney on DMSA scintigraphy was analyzed. Data were collected and analyzed using MDCake and R [2].
Results 42 patients aged 47 yrs. (12, 74) (median age; interquartile range) with a serum creatinine of 71 mmol/l (48, 112) underwent both studies within 10 days. The slope algorithm correlated more closely with DMSA SLF than the area algorithm (median difference 0 vs. 2.8 %; p < 0.05; Wilcoxon test), and there were also fewer outliers (defined as difference > 5 % against DMSA) with the slope algorithm (29 %) than with the area algorithm (40 %; n. s., Fisher’s exact test). However, the slope algorithm was more susceptible to motion artifacts (n = 4 cases) and noisy curves due to poor renal function (n = 7).
Conclusions In our preliminary analysis, split renal based on the slope algorithm correlates more closely with DMSA SLF than with the more established area algorithm. However, the slope algorithm may be more susceptible to artifacts.