Magnetic resonance imaging for precise radiotherapy of small laboratory animals.
OBJECTIVE
Radiotherapy of small laboratory animals (SLA) is often not as precisely applied as in humans. Here we describe the use of a dedicated SLA magnetic resonance imaging (MRI) scanner for precise tumor volumetry, radiotherapy treatment planning, and diagnostic imaging in order to make the experiments more accurate.


METHODS
Different human cancer cells were injected at the lower trunk of pfp/rag2 and SCID mice to allow for local tumor growth. Data from cross sectional MRI scans were transferred to a clinical treatment planning system (TPS) for humans. Manual palpation of the tumor size was compared with calculated tumor size of the TPS and with tumor weight at necropsy. As a feasibility study MRI based treatment plans were calculated for a clinical 6MV linear accelerator using a micro multileaf collimator (μMLC). In addition, diagnostic MRI scans were used to investigate animals which did clinical poorly during the study.


RESULTS
MRI is superior in precise tumor volume definition whereas manual palpation underestimates their size. Cross sectional MRI allow for treatment planning so that conformal irradiation of mice with a clinical linear accelerator using a μMLC is in principle feasible. Several internal pathologies were detected during the experiment using the dedicated scanner.


CONCLUSIONS
MRI is a key technology for precise radiotherapy of SLA. The scanning protocols provided are suited for tumor volumetry, treatment planning, and diagnostic imaging.
Universitätsklinikum Hamburg-Eppendorf, Ambulanzzentrum des UKE GmbH, Bereich Strahlentherapie, Martinistraße 52, 20246 Hamburg, Germany; Universitätsklinikum Hamburg-Eppendorf, Zentrum für Experimentelle Medizin, Institut für Anatomie und Experimentelle Morphologie, Martinistraße 52, 20246 Hamburg, Germany. Electronic address: frenzel@uke.uni-hamburg.de.
Thorsten
T
Frenzel
Universitätsklinikum Hamburg-Eppendorf, Zentrum für Radiologie und Endoskopie, Klinik und Poliklinik für Diagnostische und Interventionelle Radiologie, Martinistraße 52, 20246 Hamburg, Germany.
Michael Gerhard
MG
Kaul
Universitätsklinikum Hamburg-Eppendorf, Zentrum für Radiologie und Endoskopie, Klinik und Poliklinik für Diagnostische und Interventionelle Radiologie, Martinistraße 52, 20246 Hamburg, Germany.
Thomas Michael
TM
Ernst
Universitätsklinikum Hamburg-Eppendorf, Zentrum für Radiologie und Endoskopie, Klinik und Poliklinik für Diagnostische und Interventionelle Radiologie, Martinistraße 52, 20246 Hamburg, Germany.
Johannes
J
Salamon
Universitätsklinikum Hamburg-Eppendorf, Onkologisches Zentrum, Klinik und Poliklinik für Strahlentherapie und Radioonkologie, Martinistraße 52, 20246 Hamburg, Germany.
Maria
M
Jäckel
Universitätsklinikum Hamburg-Eppendorf, Zentrum für Experimentelle Medizin, Institut für Anatomie und Experimentelle Morphologie, Martinistraße 52, 20246 Hamburg, Germany.
Udo
U
Schumacher
Universitätsklinikum Hamburg-Eppendorf, Ambulanzzentrum des UKE GmbH, Bereich Strahlentherapie, Martinistraße 52, 20246 Hamburg, Germany.
Andreas
A
Krüll
D000818:Animals; D000830:Animals, Laboratory; D003430:Cross-Sectional Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D053783:Magnetic Resonance Imaging, Interventional; D051379:Mice; D016513:Mice, SCID; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*
Bestrahlungsplanung; Kleintierbestrahlung; Magnetic resonance imaging; Magnetresonanztomographie; Tumorvolumetrie; small animal irradiation; treatment planning; tumor volumetry