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ESTRO 36 2017
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Conclusion
This study indicates that not all PET features are robust in
a multicenter setting. Care has to be taken in feature
selection and binning method, especially if harmonization
of methods across centers is not accomplished.
Dissimilarity, homogeneity 1, and inertia seem robust and
promising PET features for use in a multicenter setting.
Use of fixed bin size should be avoided.
EP-1691 Multi-modal voxel-based correlation between
DCE-CT/MRI and DWI in metastatic brain cancer
C. Coolens
1,2,3
, W. Foltz
1,4
, N. Sinno
1
, C. Wang
1
, B.
Driscoll
1
, C. Chung
2,5
1
Princess Margaret Cancer Centre and University Health
Network, Radiation Medicine Program, Toronto, Canada
2
University Health Network, TECHNA Institute, Toronto,
Canada
3
University of Toronto, Radiation Oncology and IBBME,
Toronto, Canada
4
University of Toronto, Radiation Oncology, Toronto,
Canada
5
MD Anderson Cancer Center, Radiation Oncology,
Houston, USA
Purpose or Objective
Quantitative model-based measures of dynamic contrast
enhanced (DCE) and Diffusion Weighted (DW) MRI
parameters have shown variable findings to-date that may
reflect variability in the MR acquisition and analysis. This
work investigates the use of a voxel-based, multi-modality
GPU architecture to include various complimentary solute
transport processes into a common framework and
correlate the extra-vascular volume fraction (v
e
) and
apparent diffusion coefficient (ADC) from DCE-MRI/CT and
DWI MRI done at the same time points in patients with
brain metastases.
Material and Methods
A total of 26 tumours in 19 patients were treated under
ethics-approved trials with stereotactic radiosurgery (SRS)
alone (n=14) or SRS on day 7 of sunitinib (n=12) and
underwent multi-parametric imaging at baseline, post
drug (if applicable), then 7 and 21 days post-
radiosurgery. Each patient received a comparative DCE-
MRI scan on the same day as the CT imaging on a Verio 3T
System (IMRIS) with Variable Flip Angle (VFA) T1
quantification and 3D-FLASH and Gadolinium injection
(Magnevist 20cc); T2-weighted imaging; DWI (echo-planar
imaging with TR/TE 7700/110; 3D-diffusion gradient
encoding). Volumetric DCE-CT was acquired following a
60cc Visipaque320® injection in an intermittent time
sequence up to 3 mins (Toshiba, Aquilion ONE). A temporal
dynamic analysis (TDA) method for voxel-based CT
perfusion [1] was remodeled to enable using GPU-based
optimization on a high throughput cluster to include
various complimentary transport processes into a common
framework. As DCE-CT is considered a gold standard for
tracer-kinetic validation given its signal linearity, we
compared extravascular extracellular volume maps from
DCE-CT to those from DCE-MRI and ADC values by Pearson
correlation on a voxel-by-voxel basis as well as other
kinetic parameters using the Modified Tofts model (AUC,
K
trans
, K
ep
).
Results
Voxel-wise Pearson’s analysis showed statistically
significant correlations in K
trans
(P<0.001) between DCE-CT
and DCE-MRI over all imaging time points as well as
excellent agreement with very little bias (see Figure 1).
The correlation between ADC and v
e
values were strong in
the Sunitinib cohort (R=0.6, p<0.01, all days) and peaked
at day 3 post SRS (R=0.75, p<0.008). No such statistically
significant correlation was seen between ADC and v
e
in the
SRS alone group. Correlation of ADC histogram parameters
between imaging days was highly correlated however,
again peaking at Day 7 (R=0.85, p<0.001).
Conclusion
Using a common analysis platform has improved the
correlations in pharmaco-kinetic parameters, Ktrans and
ve, obtained from CT and MR than previously reported.
Consistent with our hypothesis that ADC and ve values
would describe a similar physiological effect, the observed
correlation between extravascular volume fraction and
ADC values was high for the cohort treated with Sunitinib
and SRS, but this correlation was not seen for the SRS
alone group.
[1] Coolens C
et al
. IJROBP. 2015;91(1):48-57.
EP-1692 Multi-device textural analysis on 18F-FDG PET
images for predicting cervical cancer recurrence
S. Reuzé
1,2,3
, F. Orlhac
3,4
, C. Chargari
1
, C. Nioche
4
, F.
Riet
1
, A. Escande
1
, C. Haie-Meder
1
, L. Dercle
5
, I. Buvat
4
,
E. Deutsch
1,2,3
, C. Robert
1,2,3
1
Gustave Roussy, Radiotherapy, Villejuif, France
2
Univ. Paris-Sud, Université Paris-Saclay, Le Kremlin-
Bicêtre, France
3
INSERM, U1030, Villejuif, France
4
IMIV, CEA- Inserm- CNRS- Univ. Paris-Sud- Université
Paris-Saclay- CEA-SHFJ, Orsay, France
5
Gustave Roussy, Nuclear Medicine and Endocrine
Oncology, Villejuif, France
Purpose or Objective
The aim of this study was to evaluate the possibility of
gathering images from 2 different PET devices in a
radiomic study, and to propose a signature of local
recurrence for locally advanced cervical cancer (LACC).
Material and Methods
118 patients with LACC were retrospectively included. All
patients underwent a
18
F-FDG PET-CT scan before
treatment. They were classified in 2 groups depending on
the PET device used for acquisition (G1: Siemens Biograph
installed in 2003, N=79; G2: GE Discovery installed 2011,
N=39). Treatment consisted in a concomitant
chemoradiation delivering 45 Gy in 25 fractions of 1.8 Gy
to the pelvis +/- the para-aortic area followed by a pulse-