Estimation of absolute renal uptake with technetium-99m dimercaptosuccinic acid: direct comparison with the radioactivity of nephrectomy specimens.
OBJECTIVE
Studies using radionuclides are the most appropriate method for estimating renal function. Dimercaptosuccinic acid chelate labeled with technetium-99m (99mTc-DMSA) is the radiopharmaceutical of choice for high-resolution imaging of the renal cortex and estimation of the functional renal mass. The aim of this study was to evaluate a simplified method for determining the absolute renal uptake (ARU) of 99mTc-DMSA prior to nephrectomy, using the radioactivity counts of nephrectomy specimens as the gold standard.


METHODS
Prospective study at the Division of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas.


METHODS
Seventeen patients (12 females; range 22-82 years old; mean age 50.8 years old) underwent nephrectomy for various reasons. Renal scintigraphy was performed three to four hours after intravenous administration of a mean dose of 188.7 MBq (5.1 mCi) of 99mTc-DMSA, which was done six to 24 hours before surgery. The in vivo renal uptake of 99mTc-DMSA was determined using the radioactivity of the syringe before the injection (measured using a dose calibrator) and the images of the syringe and kidneys, obtained from a scintillation camera. After surgery, the reference value for renal uptake of 99mTc-DMSA was determined by measuring the radioactivity of the nephrectomy specimen using the same dose calibrator.


RESULTS
The ARU measurements were very similar to those obtained using the reference method, as determined by linear regression (r-squared = 0.96).


CONCLUSIONS
ARU estimation using the proposed method before nephrectomy seems to be accurate and feasible for routine use.
Lopes de Lima
Mariana da Cunha
Mda C
Division of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil. mailto:mar.lima@terra.com.br
Ramos
Celso Darío
CD
Brunetto
Sérgio Quirino
SQ
Lopes de Lima
Marcelo
M
Ferreira
Ubirajara
U
Sá Camargo Etchebehere
Elba Cristina
EC
Santos
Allan de Oliveira
Ade O
Rodrigues Netto Júnior
Nelson
N
Camargo
Edwaldo Eduardo
EE
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000502:physiology; D007674:Kidney Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D007677:Kidney Function Tests; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D055815:Young Adult
D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid