In vivo quantification of renal function in mice using clinical gamma cameras.
BACKGROUND
In preclinical research, the growing number of transgenic models has led to the need for renal-function studies in mice. Many efforts have been made to develop dedicated SPECT systems for rodents, but their availability is limited due to high capital costs. The aim of this work is to demonstrate the feasibility of mouse renal imaging by using an inexpensive alternative based on clinical gamma-cameras.


METHODS
A healthy mouse was scanned 3 h after injection of 6 mCi of Dimercaptosuccinic acid (DMSA) labeled with 99mTc by using a single-head gamma-camera in conjunction with a dedicated pinhole collimator. List-mode data were binned to emulate multiple injections of 1 mCi, 0.1 mCi and 0.01 mCi of 99mTc-DMSA and 6-min ventral and dorsal planar images were acquired and SPECT imaging (60 projection images acquired over 60 min) was performed. An optimization of the protocols in terms of injected activity, time scan, renal cortex uniformity and cortex-to-pelvis contrast was carried out.


RESULTS
The appropriate protocols were an injected activity of 0.6 mCi, combined with duration of scanning of 1 min for planar and 60 min for SPECT imaging. Our results were validated through the relative quantification of renal function, which showed that both kidneys contributed equally to the total function. They showed that functional structures of the mouse kidneys can be visually distinguished as easily as in human studies.


CONCLUSIONS
Our findings showed the feasibility of conducting quantitative DMSA SPECT studies of anesthetized mice on clinical gamma cameras.
L2A2, University of Santiago de Compostela, Santiago de Compostela, Spain; Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Nuclear Medicine Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain.
Jesús
J
Silva-Rodríguez
Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Nuclear Medicine Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain.
Julia
J
Cortés
Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Medical Physics Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain.
Juan
J
Pardo-Montero
Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Urology Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain.
Daniel
D
Pérez-Fentes
Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Nuclear Medicine Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain; Galaria Cyclotron Unit, Santiago de Compostela, Spain.
Michel
M
Herranz
Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Nuclear Medicine Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain; In-vivo Molecular Imaging Group, Dept. of Psychiatry, Radiology and Public Health, University of Santiago de Compostela (USC), Santiago de Compostela, Spain.
Álvaro
Á
Ruibal
Molecular Imaging Group, IDIS Health Research Institute, Santiago de Compostela, Spain; Nuclear Medicine Dept, University Hospital of Santiago (CHUS), Santiago de Compostela, Spain; In-vivo Molecular Imaging Group, Dept. of Psychiatry, Radiology and Public Health, University of Santiago de Compostela (USC), Santiago de Compostela, Spain. Electronic address: pablo.aguiar.fernandez@sergas.es.
Pablo
P
Aguiar
D000818:Animals; D002138:Calibration; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007267:Injections; D007687:Kidney Tubules, Proximal / Q000000981:diagnostic imaging* / Q000502:physiology*; D055595:Mechanical Phenomena; D051379:Mice; D004113:Succimer; D013667:Technetium; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation*
D013667:Technetium; D004113:Succimer
DMSA; Pinhole SPECT; Quantitative imaging; Renal imaging; Small animal imaging