99mTc ethylene dicysteine scintigraphy for diagnosing cortical defects in acute pyelonephritis:: a comparative study with 99mTc dimercaptosuccinic acid

Aim To evaluate the clinical usefulness of early cortical phase images in the diagnosis of acute pyelonephritis and to compare the measurements of differential renal function obtained by both Tc-99m ethylene dicysteine (Tc-99m-EC) and Tc-99m dimercaptosuccinic acid (Tc-99m-DMSA). Methods Forty-three children who had undergone both Tc-99m-EC and Tc-99m-DMSA studies within 5 days of acute infection were studied. Cortical images of Tc-99m-EC were obtained by the sum of the renogram frames achieved between the first 60-120 s of the renogram study. DMSA and EC images were visually interpreted using four points of semiquantitative ratings: 0, normal; 1, mild hypoactivity; 2, moderate hypoactivity with partial loss of margins; 3, marked hypoactivity with loss of cortical margins. Values for the differential renal function were obtained for both studies. Results DMSA detected a total of 109 lesions in 36 patients and EC detected 90 lesions with a sensitivity of 82.5%. Tc-99m-EC successfully detected moderate-to-severe cortical lesions but was less effective with mild lesions (sensitivity 60%). Bland-Altman analysis demonstrated good agreement among the results for differential renal function (95% CI -0.26 to 0.96). Conclusion Tc-99m-EC early phase images detected most of the cortical lesions. Its sensitivity depends on the severity of the lesions. EC provided reliable information in the estimation of differential renal function. (C) 2004 Lippincott Williams Wilkins.