Abstract
BackgroundTo investigate the performance of quantitative indicators of MRI in early prediction of the response of gastrointestinal stromal tumor (GIST) to targeted therapy in a patient-based study.MethodsMRI examinations were performed on 62 patients with GIST using 1.5 T scanners before and at two and 12 weeks after treatment with targeted agents. The longest diameter (LD) and contrast-to-noise ratio (CNR) of the tumors were measured by T2-weighted imaging (T2WI), and the apparent diffusion coefficient (ADC) was determined using diffusion-weighted imaging (DWI). The pre-therapy and early percentage changes (%Δ) of the three parameters were compared with regard to their abilities to differentiate responder and non- responder patients, using ROC curves.ResultsThere were 42 patients in responder and 20 in non-responder group. After two weeks of therapy, the percentage changes in the ADC and LD were significantly different between the two groups (ADC: responder 30% vs. non- responder 1%, Z = − 4.819, P < 0.001; LD: responder − 7% vs. non- responder − 2%, Z = − 3.238, P = 0.001), but not in T2WI-CNR (responder − 3% vs. non-responder 9%, Z = − 0.663, P = 0.508). The AUCs on ROC for %ΔLD, %ΔT2WI-CNR and %ΔADC after two weeks of therapy were 0.756, 0.552 and 0.881, respectively, for response differentiation. When %ΔADC ≥15% was used to predict responder, the PPV was 93.3%.ConclusionsThe percentage change of the ADC after two weeks of therapy outperformed T2WI-CNR and longest diameter in predicting the early response of GIST to targeted therapy.
Highlights
To investigate the performance of quantitative indicators of MRI in early prediction of the response of gastrointestinal stromal tumor (GIST) to targeted therapy in a patient-based study
Common results One hundred and forty-one target lesions were identified on pre-therapy T2-weighted imaging (T2WI) and Diffusion-weighted MRI (DWI) images, and the longest diameter (LD), T2WI-contrast-to-noise ratio (CNR) and apparent diffusion coefficient (ADC) could be reliably measured and traced at all three examination time points
No significant differences in the three baseline parameters were found between the responder and nonresponder groups (ADC: 1.18 ± 0.27× 10− 3 mm2/s vs. 1.17 ± 0.31× 10− 3 mm2/s, F = 0.001, P = 0.972; LD: 70.58 ± 33.40 mm vs. 59.16 ± 40.55 mm, F = 0.914, P = 0.343; T2WI-CNR: 39.28 ± 22.62 vs. 30.32 ± 18.19, F = 0.359, P = 0.551) (Table 1)
Summary
To investigate the performance of quantitative indicators of MRI in early prediction of the response of gastrointestinal stromal tumor (GIST) to targeted therapy in a patient-based study. Choi et al [4] had proposed criteria that combined the size and CT values, which outperformed RECIST criteria in response evaluation of GIST It usually takes 2–3 months’ time interval for CT to detect the response change, because of the radiation impairment and insensitive soft tissue contrast. No patient-based study has been conducted to further compare the clinical performance of these variables The purpose of this patient-based study was to compare the performances of various MRI indicators in early response prediction of GIST just after two weeks of initial therapy through the comparison with three months’ treatment outcome, and to propose thresholds for clinical practices
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