This is a prospective study of 20 colorectal cancer patients with liver metastases
Inclusion criteria
Patients having hepatic metastases from pathologically proven colorectal origin with a minimum of one liver metastasis measuring at least 1 cm
Exclusion criteria
History of any other malignant disease, pregnancy, contraindications to MR imaging, and patient with contraindications to chemotherapy
Imaging
Eighteen patients performed pre-chemotherapy baseline triphasic CT with contrast. In the two remaining patients, contrast was not given due to allergy and elevated renal function, and diagnosis of metastases was based on their new appearance compared with the older studies of the patients in US and non-contrast CT while assessment of the size in the current study was done in the T2-weighted MRI sequence.
Lesions were evaluated at the portal phase, and the selected lesion/s was the largest with the maximum number of two lesions chosen as target lesions.
Baseline pre-chemotherapy axial T2-weighted sequence and DW MRI were then done before the first cycle of chemotherapy and repeated 21 days later just before the second cycle.
A follow-up CT was done 2 months later with the measurement of the target lesions.
CT examinations were performed using 64 slice equipment (acquiring images from the top of the liver to the pubic symphysis, before and after the intravenous injection of contrast agent (1.5 ml/kg body weight), during arterial and portal venous phases (35–40 s and 70–75 s after injection, respectively).
MRI was performed using a 1.5-T MRI scanner (SIEMENS-MAGNETOM_ ESSENZA) equipped with phased-array torso surface coil.
Axial T2-weighted free-breathing, with TR (2000), TE (80), matrix (256 × 179), slice thickness (6.5 mm), and gap (20% = 0.8 mm) in the axial plane.
Diffusion-weighted echo-planar imaging (EPI) sequence with TR (4500), TE (73), matrix (192 × 120), slice thickness (7 mm), and gap (50% = 2 mm) in axial plane. The b values were 50, 400, and 800 with computer-generated ADC map.
Image analysis on MRI
Images were analyzed by two radiologists independently (consultant and resident), the results were compared, and mismatching results were re-assessed in conjoint.
The lesions corresponding to the ones chosen on CT were identified.
A similar-sized ROI was placed at the same site on the pre- and post-chemotherapeutic images and the two ADC values were compared.
CT image analysis
The maximum diameter of each metastatic lesion was measured before and after treatment. Analysis of the results was done according to the Response Evaluation Criteria in Solid Tumors (RECIST).
A metastatic lesion presenting a 20% or more increase in the maximum transverse diameter with respect to time 0 was classified as progressive disease (PD), a lesion showing at least 30% of reduction in the maximum transverse diameter with respect to time 0 was classified as partial response (PR). A lesion not presenting such dimensional decrease or increase was considered stable disease (SD). From a clinical point of view, lesions with complete cure or regressing (CR and PR, respectively) were also labeled as responding (R), while those progressing and stable were classified as not responding (NR).
Statistical analysis
Data were fed to the computer and analyzed using IBM SPSS software package version 20.0 (Armonk, NY: IBM Corp). Qualitative data were described using number and percent. Quantitative data were described using range (minimum and maximum), mean, standard deviation, and median. Significance of the obtained results was judged at the 5% level.