Assessment of Renal Function Based on Dynamic Scintigraphy Parameters in the Diagnosis of Obstructive Uro/Nephropathy

Abstract

This study evaluates the usefulness of parameters allowing assessment of renal function in absolute values in dynamic renal scintigraphy (DRS) with 99mTc-ethylenedicysteine (99mTc-EC) uptake constant (K), mean transit time (MTT), and parenchymal transit time (PTT) in the diagnosis of obstructive uro/nephropathy. The study included 226 people: 20 healthy volunteers, for whom normative values of assessed parameters were determined, and 206 patients. Reproducibility of results obtained by two independent operators, specificity, correlation with estimated GFR (eGFR), and Cohen’s kappa were used to evaluate reliability of assessed parameters. Normative values were as follows: K ≥ 1.6, MTT ≤ 250 s, and PTT ≤ 225 s. Reproducibility of determination of K (rs = 0.99) and MTT (rs = 0.98) was significantly higher than that of PTT (rs = 0.95) (p = 0.001). Specificity was 100% for K, 81% for MTT, and 91% for PTT. Correlation of eGFR with K (rs = 0.89) was significantly higher than with PTT (rs = 0.53) and with split function (SF) (rs = 0.66) (p < 0.0001). Cohen’s kappa was κ = 0.89 for K, κ = 0.88 for MTT, and κ = 0.77 for PTT. In a group of patients where standard DRS parameters are unreliable (bilateral obstructive uro/nephropathy or single functioning kidney), the use of K (the most effective among assessed parameters) changed the classification of 23/79 kidneys (29%). K enables reproducible assessment of absolute, individual kidney function without modifying routine DRS protocol. Diagnostic value of MTT and PTT is limited.

Basic principles and new advances in kidney imaging

“…20 99mTc-PAH, owing to its fast kinetics, excretion properties, and high-quality images, shows promise as a substitute for 99mTc-DTPA, 21 and 99mTc-EC scintigraphy shows promise for diagnosis of obstructive uro-nephropathy. 22 Multidetector CE-CT affords quantifications of total and regional perfusion using indicator-dilution curves in patients with renovascular disease and hypertension, 23,24 and GFR can be concurrently quantified as well. 25 PET, a reference standard for quantitative cortical perfusion, 26 also allows molecular imaging.…”

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

“…Diuretic renography is a simple, non-invasive test for the dynamic assessment of kidney obstruction and functions initially described in the late 1950s. This modality is based on realtime scanning of an intravenously administrated radiopharmaceutical agent via dynamic kidney scintigraphy (DRS) to draw activity curves for kidney functions [11] . Diuretic renography provides both qualitative and quantitative measures of kidney functions, such as the relative function of each kidney and the time of the peak of the renographic curve (Tmax) [12] .…”

“…A growing body of evidence has demonstrated the utility and reliability of 99mTc-MAG3 diuretic renography in a wide range of kidney disorders, such as identifying kidney obstruction, uropathy, hydronephrosis, and after chemotherapy [11][12][13][14] . The vast majority of the agent (95%) is excreted by the proximal kidney tubules, which permits real-time evaluation of the excretory functions of the kidney, as well as the assessment of any obstruction in the kidney flow through the pelvicalyceal system and bladder [12] .…”

“…The 99mTc-MAG3 agent has been proven for safe use in both children and adults [13] . In addition, 99mTc-MAG3 has shown higher binding affinity to protein, leading to slow plasma clearance, which in turn resulting in high-quality imaging regardless of kidney failure [11] . I It is usually preferred over the other agents (such as Tc-99m DTPA) due to its high plasma clearance value (40%) and a shorter half-life, making it more practical to evaluate kidney function.…”