Standardized Index of Shape (DCE-MRI) and Standardized Uptake Value (PET/CT): Two quantitative approaches to discriminate chemo-radiotherapy locally advanced rectal cancer responders under a functional profile.

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Petrillo, Antonella 
Fusco, Roberta 
Petrillo, Mario 
Granata, Vincenza 
Delrio, Paolo 

PURPOSE: To investigate dynamic contrast enhanced-MRI (DCE-MRI) in the preoperative chemo-radiotherapy (CRT) assessment for locally advanced rectal cancer (LARC) compared to18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). METHODS: 75 consecutive patients with LARC were enrolled in a prospective study. DCE-MRI analysis was performed measuring SIS: linear combination of percentage change (Δ) of maximum signal difference (MSD) and wash-out slope (WOS). 18F-FDG PET/CT analysis was performed using SUV maximum (SUVmax). Tumor regression grade (TRG) were estimated after surgery. Non-parametric tests, receiver operating characteristic were evaluated. RESULTS: 55 patients (TRG1-2) were classified as responders while 20 subjects as non responders. ΔSIS reached sensitivity of 93%, specificity of 80% and accuracy of 89% (cut-off 6%) to differentiate responders by non responders, sensitivity of 93%, specificity of 69% and accuracy of 79% (cut-off 30%) to identify pathological complete response (pCR). Therapy assessment via ΔSUVmax reached sensitivity of 67%, specificity of 75% and accuracy of 70% (cut-off 60%) to differentiate responders by non responders and sensitivity of 80%, specificity of 31% and accuracy of 51% (cut-off 44%) to identify pCR. CONCLUSIONS: CRT response assessment by DCE-MRI analysis shows a higher predictive ability than 18F-FDG PET/CT in LARC patients allowing to better discriminate significant and pCR.

DCE-MRI and FDG-PET/CT, neoadjuvant chemo-radiotherapy, rectal cancer, treatment response assessment, Adult, Aged, Area Under Curve, Chemoradiotherapy, Adjuvant, Contrast Media, Digestive System Surgical Procedures, Female, Fluorodeoxyglucose F18, Humans, Magnetic Resonance Imaging, Magnetite Nanoparticles, Male, Middle Aged, Neoadjuvant Therapy, Perfusion Imaging, Positron Emission Tomography Computed Tomography, Predictive Value of Tests, ROC Curve, Radiopharmaceuticals, Rectal Neoplasms, Regional Blood Flow, Remission Induction, Reproducibility of Results, Siloxanes, Treatment Outcome
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