Keywords:
Metastases, Ablation procedures, MR-Diffusion/Perfusion, MR, Oncology, Liver
Authors:
O. W. Kozak1, T. Nowicki2, J. Pienkowska2, E. Izycka-Swieszewska2, D. Zadrozny2, E. Szurowska2; 1Gdańsk, po/PL, 2Gdansk/PL
DOI:
10.1594/ecr2018/C-1544
Methods and materials
We analysed the MRI studies of 52 patients (18 women,
34 men,
aged 43-83).
The inclusion criteria of the study were a) colorectal adenocarcinoma confirmed by histological examination,
b) presence of metastatic lesions in the liver diagnosed by multiphase contrast-enhanced CT and/or dynamic contrast-enhanced MR (without liver biopsy),
c) number of metastatic foci in the liver between 1 and 5 and size of the foci between 10 and 50mm,
d) disqualification from surgical treatment,
d) progression during or after chemotherapy,
e) qualification to RFA treatment,
f) no contraindications to MR examination.
The exclusion criteria were significant artifacts in DWI imaging.
Patients underwent MR examination of the liver up to 24 hours before RFA therapy.
MR study was performed using GE Signa 1.5 T MR system (GE Healthcare,
Milwaukee,
WI) with the eight-channel phased-array coil,
rise time 183.3 μs,
slew rate 120 mT/m.
Axial images of the whole liver were acquired with the breath-hold technique in expiration.
The protocol included T1-weighted fast spoiled gradient echo sequences,
T2-weighted fast relaxation fast spin echo sequences and DWI.
DWI technique (a single-shot echo planar imaging technique) was applied in anterior-posterior direction with b values of 0,
15 and 500 s/mm2.
ADC maps were calculated for b values of 0-15 and 0-500 s/mm2.
The RFA therapy outcome was assessed on the basis of follow-up multiphase contrast-enhanced CT examination at 6 weeks,
3 months,
or 6 months after the treatment.
The MRI examinations obtained before RFA therapy were evaluated by two independent radiologists with at least 10 years of experience in abdominal radiology.
The mean ADC value was obtained by threefold marking ROI covering the whole metastatic lesion.
On the basis of RFA outcomes and ROC analysis,
the cut-off values of ADC were established: 2.49 mm2/s for b value of 0-15 s/mm2 and 1.43 mm2/s for b value of 0-500 s/mm2.
The survival outcomes depending on the ADC cut-off values were assessed by means of Kaplan-Meier estimator.
In case of multiple foci,
only the lesion with the highest ADC value was included in the analysis (one per patient).
The p-value lower than 0.05 was considered significant.