123I-hippuran renal scintigraphy with evaluation of single-kidney clearance for predicting renal scarring after acute urinary tract infection: comparison with (99m)Tc-DMSA scanning.
The value of (123)I-hippuran (OIH) renal sequential scintigraphy (RSS) in predicting the evolution of defects detected by (99m)Tc-dimercaptosuccinic acid (DMSA) scanning during a first episode of acute pyelonephritis (APN) was assessed.


METHODS
Fifty-eight children with APN underwent (99m)Tc-DMSA planar scanning and (123)I-OIH RSS during acute infection and at least 5 mo later. Renal lesions found by (99m)Tc-DMSA scanning were classified according to the following (99m)Tc-DMSA grading system: 0 = normal, 1 = 1 lesion, 2 = 2 lesions, and 3 = diffuse damage with renal parenchymal subversion. Renal scarring was diagnosed whenever a renal cortical defect detected at the first (99m)Tc-DMSA examination persisted on the follow-up (99m)Tc-DMSA examination. Single-kidney clearance rate (Cl) was evaluated by a method that was previously validated at our institution and is based on time-activity curves measured on the heart and kidney areas by the region-of-interest technique.


RESULTS
(99m)Tc-DMSA scanning showed renal damage in 76 kidneys and had negative findings for the remaining 40 kidneys (2 patients had bilaterally negative findings). (99m)Tc-DMSA scanning determined 40 kidneys to be grade 0, 49 to be grade 1, 21 to be grade 2, and 6 to be grade 3. For (99m)Tc-DMSA grades of 0-3, the corresponding Cl mean values (in mL/min/1.73 m(2) of body surface area [BSA]) were 292 +/- 33, 237 +/- 39, 210 +/- 54, and 140 +/- 53, respectively. The Spearman regression coefficient (R) demonstrated a significant correlation between (99m)Tc-DMSA grade and Cl (R = 0.69, P < 0.0001). Thirty-six of the lesions detected by staging (99m)Tc-DMSA were shown to have recovered on follow-up renal scans, whereas 40 developed scars. A significant difference in Cl was found between the 2 groups (P < 0.0002). The Cl cutoff value was determined by univariate discriminant analysis; a Cl value of 232 mL/min/1.73 m(2) of BSA discriminated best between scarred and nonscarred kidneys, with a specificity, sensitivity, positive predictive value, negative predictive value, and overall accuracy of 95%, 95%, 90%, 97%, and 95%, respectively.


CONCLUSIONS
Cl evaluation, in the course of acute urinary tract infection, is highly valuable in predicting the fibrotic evolution of renal damage detected on acute (99m)Tc-DMSA scanning. Also, our data show close agreement between Cl and the grade determined by staging (99m)Tc-DMSA.
Imperiale
Alessio
A
Department of Clinical Pathophysiology, University of Florence, Florence, Italy.
Olianti
Catia
C
Sestini
Stelvio
S
Materassi
Marco
M
Seracini
Daniela
D
Ienuso
Rita
R
La Cava
Giuseppe
G
Daniela
Seracini
S
D000208:Acute Disease; D002675:Child, Preschool; D002921:Cicatrix / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007457:Iodine Radioisotopes; D007465:Iodohippuric Acid; D007668:Kidney / Q000000981:diagnostic imaging*; D008297:Male; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D014552:Urinary Tract Infections / Q000000981:diagnostic imaging*
D007457:Iodine Radioisotopes; D007465:Iodohippuric Acid; D019783:Technetium Tc 99m Dimercaptosuccinic Acid