Imaging Cancer in Mice by PET, CT, and Combined PET‐CT

Francisca Mulero1, Luis E. Donate1, Manuel Serrano1

1 Spanish National Cancer Research Centre (CNIO), Madrid, Spain
Publication Name:  Current Protocols in Mouse Biology
Unit Number:   
DOI:  10.1002/9780470942390.mo100137
Online Posting Date:  March, 2011
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Abstract

The possibility of imaging tumors in live mice has opened new opportunities for cancer research, particularly regarding the ability to perform longitudinal studies in combination with a therapeutic intervention. Here, we detail methods to optimize visualization of murine tumors by positron emission tomography (PET), computed tomography (CT), and combined PET‐CT. Curr. Protoc. Mouse Biol. 1:85‐103. © 2011 by John Wiley & Sons, Inc.

Keywords: cancer; mouse models; positron electron tomography; computed tomography

     
 
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Table of Contents

  • Introduction
  • Basic Protocol 1: Imaging by Positron Emission Tomography (PET)
  • Basic Protocol 2: Imaging by Computed Tomography (CT)
  • Basic Protocol 3: Imaging by Multimodality (PET‐CT)
  • Reagents and Solutions
  • Commentary
  • Literature Cited
  • Figures
  • Tables
     
 
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Materials

Basic Protocol 1: Imaging by Positron Emission Tomography (PET)

  Materials
  • Genetically modified mouse models bearing spontaneous tumors in any body location
  • Special mouse diets as necessary
  • Diazepam (5 mg/ml in flip‐top vial; see recipe)
  • Isoflurane
  • Oxygen
  • [18F]FDG (0.01 to 0.1 µg/ mCi), delivered daily from a local cyclotron (e.g., 40 mCi of [18F]FDG of 95% to 99% radiochemical purity in 1 ml of physiological saline solution buffered at pH 6.0, for ∼10 PET scans)
  • Physiological saline: 0.9% (w/v) NaCl
  • Lacryvisc Gel 10 G (3 mg/ml carbomere in benzalconium chloride, commercially available from Alcon, http://www.alcon.com)
  • Infrared heating lamp
  • Isoflurane/oxygen‐based anesthesia system fitted with an induction chamber and inhalation masks for mice
  • Dose calibrator (also known as activimeter): e.g., VDC‐505 dose calibrator from Veenstra Instruments (http://www.dosecalibrator.com/)
  • PET‐CT imaging system: e.g., eXplore Vista PET‐CT, GE Healthcare (Fig. A); Argus PET‐CT, SEDECAL (http://www.sedecal.com/)
  • 1‐cc tuberculin syringes
  • 30‐G needles
  • Heating pads: e.g., Gaymar Mul‐T‐Pads (http://www.gaymar.com/)
  • Heating pump to maintain temperature of heating pads: e.g., Gaymar TP600 (http://www.gaymar.com/)
  • eXplore Vista PET‐CT MMWKS software for image acquisition, processing, and analysis
  • Workstation (e.g., Dell PowerEdge) for image acquisition, processing, and analysis meeting the following specifications:
    • PE1950 Xeon 5120 1.86 GHz/4 MB 1066 FSB processor
    • PE1950 PCIX Riser (2 slots)
    • PE1950 Bezel Assembly
    • 2 GB FB 667 MHz Memory (2 × 1 GB dual rank DIMMs)
  • Dell Studio XPS Desktop 435 MT PC (for 3DOSEM image reconstruction) meeting the following specifications:
    • Processor: Intel Core i7 Quad CPU 940 4 × 2.93 GHz
    • Memory: 6144 MB (6 × 1024) 1067 MHZ DDR3
    • Graphics: ATI Radeon HD 3450 256 Mb GDDR2

Basic Protocol 2: Imaging by Computed Tomography (CT)

  Materials
  • Computed tomography system (e.g., CT Locus from GE Healthcare or CT eXplore Vista from GE Healthcare)
  • eXplore Vista PET‐CT MMWKS software for image acquisition, processing and analysis (incorporating a modified version of the FDK algorithm for CT reconstruction); or Microview for Locus CT for image analysis
  • Additional reagents and equipment for imaging by PET ( protocol 1)

Basic Protocol 3: Imaging by Multimodality (PET‐CT)

  Materials
  • PET‐CT imaging system (e.g., eXplore Vista PET‐CT, GE Healthcare; Fig. A)
  • Additional reagents and equipment for PET ( protocol 1) and imaging by computed tomography ( protocol 2)
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Figures

  •   FigureFigure 1. Equipment at a PET‐CT facility for mice. (A) PET‐CT machine (eXplore Vista, GE Healthcare). (B) Monitor of vital constants (VisionVet, RGB) registering ECG, temperature, and respiratory frequency. (C) Mouse fitted with electrodes and monitoring probes being introduced into a PET‐CT machine.
  •   FigureFigure 2. Administration of the probe. Tail vein injection of the radioactive probe into a mouse with anesthetic mask and using a shielded syringe.
  •   FigureFigure 3. Example of ROI selection in a CT scan. (A) The example shows three serial CT transversal sections separated by 0.6 mm. The operator manually outlines the perimeter of the tumor in a section where the tumor is clearly detectable (such as in the middle section). The software automatically draws the same outline in adjacent sections separated every 50 µm. The operator can modify the outline to adapt it to the changing dimensions of the tumor (such as in the upper and lower sections). The software integrates all the sections into the volume corresponding to the ROI (region of interest). (B) From top to bottom, sagittal, coronal, and transverse sections of the CT volume. The ROI, visible in all three sections, is shown in solid green.
  •   FigureFigure 4. PET‐CT imaging of a lung tumor. (A) Transverse CT section. From top to bottom, liver (lv) and heart (h). The orange arrow points to the ROI, a lung tumor. (B) Transverse PET section of the same anatomic area as in A. (C) Histological section of the same lung imaged at the optical microscope by Hematoxylin & Eosin staining. Two tumors of different dimensions were detected: the one already observed by PET‐CT (orange arrow) and a smaller one (blue arrow) that was not detected by PET‐CT probably due to its intrabronchial location. (D) 3‐D rendering of the PET‐CT image merged with the lung. The tumor is shown as a pinkish‐colored small ball.
  •   FigureFigure 5. Example of a longitudinal study of lung cancer. 3‐D lung renderings of PET‐CT studies at the indicated time‐points of two individual mice carrying genetically induced lung tumors, either treated with vehicle (upper mouse) or with a therapeutic compound (lower mouse). Mouse model courtesy of Dr. Mariano Barbacid (CNIO).

Literature Cited

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Internet Resources
  https://www2.gehealthcare.com/portal/site/usen/menuitem.e8b305b80b84c1b4d6354a1074c84130/?vgnextoid=ea21351f9b7e0210VgnVCM10000024dd1403RCRD&productid=da21351f9b7e0210VgnVCM10000024dd1403
  General Electric Triumph Tri‐modality PET/SPECT/CT.
  http://www.sedecal.com/en/divisiones/division_prod.php?p=44&c=5&i=2
  SEDECAL Argus PET‐CT.
  http://www.medical.siemens.com/webapp/wcs/stores/servlet/CategoryDisplay∼q_catalogId∼e_‐11∼a_categoryId∼e_1029715∼a_catTree∼e_100010,1007660,1011525,1029715∼a_langId∼e_‐11∼a_storeId∼e_10001.htm
  Siemens Inveon PET & Inveon CT.
  http://www.healthcare.philips.com/main/products/preclinical/
  Philips Mosaic HP PET.
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