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

Antonella Petrillo,Luigi Aloj,Vincenza Granata,Antonio Avallone,Gerardo Botti,Paolo Delrio,Francesco Bianco,Corradina Caracò,Biagio Pecori,Mario Petrillo,Roberta Fusco,Secondo Lastoria,Fabiana Tatangelo

doi:10.18632/oncotarget.14106

Antonella Petrillo, Luigi Aloj + Show 11 more

Open Access

https://doi.org/10.18632/oncotarget.14106

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Abstract

PurposeTo 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).Methods75 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.Results55 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.ConclusionsCRT 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.

Highlights

Forty thousand new cases of rectal cancer are accounting in the USA in 2015 [1]
ΔSIS reached sensitivity of 93%, specificity of 80% and accuracy of 89% to differentiate responders by non responders, sensitivity of 93%, specificity of 69% and accuracy of 79% to identify pathological complete response
We investigated a semiquantitative analysis with Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI) [14,15,16,17,18,19,20], finding the best combination, denominated Standardized Index of Shape (SIS), that identifies the linear classifier of the percentage differences Δ of Maximum Signal Difference (MSD) and of Wash-Out Slope (WOS) [7], with a sensitivity and specificity of 93.5% and 82.1% in discrimination of responder by non responder patients after pCRT [13]

Summary

Introduction

Forty thousand new cases of rectal cancer are accounting in the USA in 2015 [1]. TME is linked to morbidity and complications, in clinical practise there is an increase of conservative treatment strategies application for patients with substantial tumor regression after pCRT and “wait and see” policy for patients with complete pathological regression. The advantage of this strategy is the reduction of morbidity and the possibility to provide a “true” organ-sparing approach. It is difficult to discriminate between post treatment fibrosis and residual viable tumor using morphological approach To overcome this limitation, functional approaches that aim to assess tissue “viability” through different imaging modalities such as Position Emission Tomography, Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI), Diffusion Weighted Magnetic Resonance Imaging (DWI) are being actively investigated. Among data reported in literature [7,8, 10], late PET scans, performed before surgery, showed lower accuracy in pathologic response assessment

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