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

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.

Diffusion kurtosis imaging in patients with locally advanced rectal cancer: current status and future perspectives

“…1 The standard of care for patients with locally advanced rectal cancer (LARC) is preoperative chemoradiotherapy (pCRT) followed by total mesorectal excision. 2–4 In addition, for patients with a complete response to pCRT, there has been a surge of conservative management and the “wait-and-see” strategy. 5 The benefit of this policy is a decreased morbidity rate and the opportunity to administer “true” organ-sparing therapy.…”

Assessing response to neo-adjuvant therapy in locally advanced rectal cancer using Intra-voxel Incoherent Motion modelling by DWI data and Standardized Index of Shape from DCE-MRI

“… 11 – 16 , 39 , 40 We demonstrated the ability of SIS to detect complete and significant response after pCRT in LARC 15 and the strength of SIS compared with fluorodeoxyglucose positron-emission tomography ( 18 F-FDG-PET) examination. 41 Some studies demonstrated the role of DWI in LARC for assessing therapy response 39 , 40 and several studies evaluated the use of the IVIM model for extracting DWI data by both perfusion and diffusion parameters in different types of tumours. 32 , 33 , 42 In our previous study, 10 we compared SIS with diffusion parameters and their combination after short-course radiotherapy in LARC, demonstrating that no accuracy increase was obtained combining linearly each possible perfusion and diffusion parameter couple extracted by DCE-MRI and DWI or combining all functional MR-derived parameters with respect to SIS alone.…”

Magnetic resonance tumor regression grade (MR-TRG) to assess pathological complete response following neoadjuvant radiochemotherapy in locally advanced rectal cancer

“…Several studies investigated the accuracy of DCE-MRI reporting variable results. However, the evaluation of standardized index of shape (SIS), demonstrated to be the most accurate and reproducible method to identify CRs with a sensitivity higher than 90% and a specificity higher than 80% [ 27 , 28 ].…”