Inhomogeneous localization of radioactivity in the human kidney after injection of [(111)In-DTPA]octreotide.
In peptide receptor radionuclide therapy (PRRT) using somatostatin analogs labeled with beta-emitters, the radiosensitive kidney is the dose-limiting organ, because of high uptake and retention of the radionuclides after glomerular filtration. Dosimetry calculations are mostly based on the MIRD scheme, assuming homogeneous renal radioactivity distribution. The aim of this study was to reveal the radioactivity distribution in the normal human kidney after intravenous injection of [(111)In-diethylenetriaminepentaacetic acid (DTPA)]octreotide.


METHODS
Three patients received intravenous injection of [(111)In-DTPA]octreotide before nephrectomy because of renal cancer. Distribution of radioactivity in the human kidney was investigated using SPECT scanning before and ex vivo autoradiography of the kidney after surgery.


RESULTS
Radioactivity was localized predominantly in the cortex of the kidney. In the cortex, radioactivity was not distributed homogeneously but formed a striped pattern, with most of the radioactivity centered in the inner cortical zone.


CONCLUSIONS
These findings show that average dose calculations using the MIRD scheme, assuming homogeneous renal radioactivity distribution, are inadequate to estimate the radiation dose to various parts of the kidney after PRRT. Different effects due to inhomogeneity can be expected from PRRT using radionuclides emitting particles with short particle ranges, for example, Auger electron emitters, alpha-emitters, and low-energy beta-emitters.
De Jong
Marion
M
Department of Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands. m.hendricks-dejong@erasmusmc.nl
Valkema
Roelf
R
Van Gameren
Arthur
A
Van Boven
Hester
H
Bex
Axel
A
Van De Weyer
Eric Pieter
EP
Burggraaf
Jan Dirk
JD
Körner
Meike
M
Reubi
Jean-Claude
JC
Krenning
Eric P
EP
D000368:Aged; D001345:Autoradiography / Q000379:methods*; D001822:Body Burden; D006801:Humans; D007275:Injections, Intravenous; D007668:Kidney / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics*; D009928:Organ Specificity; D004369:Pentetic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon
D019275:Radiopharmaceuticals; C071632:SDZ 215-811; D004369:Pentetic Acid; D015282:Octreotide