5th EuropEan MolEcular IMagIng MEEtIng - ESMI

5th EuropEan MolEcular IMagIng MEEtIng – EMIM2010
TF-Pimonidazole: an hypoxia marker suitable for in vivo 19 F MRS imaging
Heerschap, A. .
Centre for Molecular Life Science, University Nijmegen, The Netherlands
a.heerschap@rad.umcn.nl
Introduction: Hypoxia in tumours is associated
with enhanced progression, increased aggressiveness
and metastatic potential and poor prognosis.
Moreover, hypoxic tumour cells are resistant to
radiotherapy and some forms of chemotherapy.
Over the years several approaches to assess hypoxia
in vivo have been explored, ranging from
needles measuring local pO 2 invasively to a range
of non-invasive (imaging) methods using oxygen
sensitive agents. Unfortunately until today none
of these methods or agents has entered widespread
clinical practice. Here we demonstrate a
novel hypoxia marker completely analogous to
the commonly used histological hypoxia marker
Pimonidazole (PIMO) and labelled with fluorine
for in vivo 19 F MRS imaging.
Methods:1-(2-nitro-1H-imidazol-1-yl)-3-[4-
(trifluoromethyl)piperidin-1-yl]propan-2-ol
(TF-PIMO) was synthesized in a similar way as
described in [1]. C57BL/6 mice carrying a C38
colon carcinoma on the upper leg (size approx.
250 mm 3 ) were given either 80 or 200 mg / kg TF-
PIMO intraperitoneal (IP) at least 3 hours before
MR investigations. The mice were anesthetized
using a single urethane IP injection. This avoids
any spectral interference by fluorinated inhalation
anaesthetics. Experiments were performed
on a 7 T horizontal bore MR system. A homemade
14 mm solenoid coil was used for transmit/receive
of 19 F and 1 H. After initial localization and basic
1 H MR imaging (T2*w GRE) an unlocalized pulse
acquire sequence (FID) on 19 F was used to detect
TF PIMO validating correct injection of the compound.
Subsequently a series of 3D 19 F chemical
shift imaging (CSI) FID experiments using an
ultrashort adiabatic half passage pulse was used
for TF-PIMO 19 F imaging. Further settings of the
MRSI sequence: FOV 32 × 32 ×32 mm, matrix
8 × 8 × 8, TR 597 ms, acquisition time 58 m 02
s, 256 averages, weighted phase encoding scheme.
After MR, tumours were removed immediately
and stored in liquid nitrogen. Frozen tumour sections
of 5 μm thickness were cut for staining and
further analysis. The tumor sections were subsequently
stained and scanned for Hoechst and rabbit
anti-pimonidazole.
Results: Figure 1 shows a heat map generated from
the 3D 19 F MRSI representing the in vivo TF-PIMO
accumulation in a hypoxic C38 colon carcinoma as
was validated by subsequent immunohistochemical
analysis of the tumour tissue.
Figure 1: 1H MRI of a C38 murine colon carcinoma on a mouse leg
with a heat map generated from a 3D 19F MRSI representing the in
vivo TF-PIMO accumulation over-layed.
Conclusions: TF-PIMO was synthesized and shown
to be a potential non-invasive marker to image tissue
hypoxia in tumours by 19F MRSI. Background
free functional images are obtained that can be coregistered
with conventional MRI. In addition this
marker has the advantage that it can be stained with
the same anti-body as used to detect the common
clinical used marker Pimonidazole and thus allows
for easy matching of hypoxia by histology and by
MR on the same tumour sample.
Acknowledgement: This work is supported in part
by EMIL (LSHC-CT-2004-503569) and NWO (VIS-
TA and INV911-06-021)
References:
1. Raleigh, J. A. et al; Magn Reson Med 22:451-466 (1991)
EuropEan SocIEty for MolEcular IMagIng – ESMI
day1
Parallel Session 1: CANCER I - together with the ESR