99mTc-MAG3 Diuretic Renography: Intra- and Inter-Observer Repeatability in the Assessment of Renal Function

Abstract

The aim of the present study is to evaluate the intra- and inter-observer agreement in assessing the renal function by means of 99mTc-MAG3 diuretic renography. One hundred and twenty adults were enrolled in the study. One experienced and one junior radiographer processed the renograms twice by assigning manual and semi-automated regions of interest. The differential renal function (DRF, %), time to maximum counts for the right and left kidney (TmaxR-TmaxL, min) and time to half-peak counts (T1/2, min) were calculated. The Bland–Altman analysis (bias±95% limits of agreement), Lin’s concordance correlation coefficient and weighted Fleiss’ kappa coefficient were used to assess agreement. Based on the Bland–Altman analysis, the intra-observer repeatability results for the experienced radiographer using the manual and the semi-automated techniques were 0.2 ± 2.6% and 0.3 ± 6.4% (DRF), respectively, −0.01 ± 0.24 and 0.00 ± 0.34 (TmaxR), respectively, and 0.00 ± 0.26 and 0.00 ± 0.33 (TmaxL), respectively. For the junior radiographer, the respective results were 0.5 ± 5.0% and 0.8 ± 9.4% (DRF), 0.00 ± 0.44 and 0.01 ± 0.28 (TmaxR), and 0.01 ± 0.28 and −0.02 ± 0.44 (TmaxL). The inter-observer repeatability for the manual method was 0.6 ± 5.0% (DRF), −0.10 ± 0.42 (TmaxR) and −0.05 ± 0.38 (TmaxL), and for the semi-automated method −0.2 ± 9.1% (DRF), 0.00 ± 0.31 (TmaxR) and −0.05 ± 0.40 (TmaxL). The weighted Fleiss’ kappa coefficient for the T1/2 assessments ranged between 0.85–0.97 for both intra- and inter-observer repeatability with both methods. These findings suggest a very good repeatability in DRF assessment with the manual method—especially for the experienced observer—but a less good repeatability with the semi-automated approach. The calculation of Tmax was also operator-dependent. We conclude that reader experience is important in the calculation of renal parameters. We therefore encourage reader training in renal scintigraphy. Moreover, the manual tool seems to perform better than the semi-automated tool. Thus, we encourage cautious use of automated tools and adjunct validation by manual methods where possible.

Spectrum of Disorders Diagnosed on 99mTc-MAG3 Radioisotope Renography: A Report of 260 Saudi Arabian Patients

“…This is in accordance with study by Taylor et al, who elaborated that the acceptable and safe dose for 99mTc-MAG3 was 37-185 MBq [27] . Other reports and expert opinions supported these findings [28,29] . According to Sachpekidis et al, this dose range is sufficient to ensure the reliability of 99mTc-MAG3 diuretic renography [28] .…”

Timing of diuretics in diuresis renography

“…The included articles were published between the years 1978 and 2020 [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The number of participants varied between 14 and 320.…”

“…The radiopharmaceutical 99m Tc-MAG3 was administered in six studies [11, 17-19, 24, 25], 99m Tc-DTPA in five studies [9,12,13,20,22], 123 I-OIH in four studies [15,16,21,23], 99m Tc-EC in one study [10] and one study did not mention which radiopharmaceutical had been administered [14]. Five studies had a retrospective study design [15,17,22,24,25] and 12 studies had a prospective study design [9-14, 16, 18-21, 23]. Four articles included both children and adults in their studies [16,17,20,22], Table 3.…”

“…Five studies did not compare different methods with each other; instead, they addressed a certain question and described which of the different methods they had used in their studies [12,[21][22][23]25]. Arap et al described the F + 15 method and reported that diuretic administration allowed differentiation between obstructive and hypotonic processes [21].…”

“…Altarac S. introduced and evaluated an obstruction score system based on the F − 15 method [12]. Sachpekidis et al evaluated the intra-and inter-observer agreement when assessing the renal function in diuresis renography when using the F + 10 method and, reported that the reader's experience is important when calculating renal parameters and that reader training could be of value [25].…”