title: Accuracy and reproducibility of tumor positioning during prolonged and multi-modality animal imaging studies.
abstract: Dedicated small-animal imaging devices, e.g. positron emission tomography (PET), computed tomography (CT) and magnetic resonance imaging (MRI) scanners, are being increasingly used for translational molecular imaging studies. The objective of this work was to determine the positional accuracy and precision with which tumors in situ can be reliably and reproducibly imaged on dedicated small-animal imaging equipment. We designed, fabricated and tested a custom rodent cradle with a stereotactic template to facilitate registration among image sets. To quantify tumor motion during our small-animal imaging protocols, 'gold standard' multi-modality point markers were inserted into tumor masses on the hind limbs of rats. Three types of imaging examination were then performed with the animals continuously anesthetized and immobilized: (i) consecutive microPET and MR images of tumor xenografts in which the animals remained in the same scanner for 2 h duration, (ii) multi-modality imaging studies in which the animals were transported between distant imaging devices and (iii) serial microPET scans in which the animals were repositioned in the same scanner for subsequent images. Our results showed that the animal tumor moved by less than 0.2-0.3 mm over a continuous 2 h microPET or MR imaging session. The process of transporting the animal between instruments introduced additional errors of approximately 0.2 mm. In serial animal imaging studies, the positioning reproducibility within approximately 0.8 mm could be obtained.
authors.affiliation: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Mutian
authors.initials: M
authors.lastname: Zhang
authors.forename: Minming
authors.initials: M
authors.lastname: Huang
authors.forename: Carl
authors.initials: C
authors.lastname: Le
authors.forename: Pat B
authors.initials: PB
authors.lastname: Zanzonico
authors.forename: Filip
authors.initials: F
authors.lastname: Claus
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Kolbert
authors.forename: Kyle
authors.initials: K
authors.lastname: Martin
authors.forename: C Clifton
authors.initials: CC
authors.lastname: Ling
authors.forename: Jason A
authors.initials: JA
authors.lastname: Koutcher
authors.forename: John L
authors.initials: JL
authors.lastname: Humm
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D051381:Rats; D011923:Rats, Nude; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique