This house believes multiparametric MRI is the holy grail for organ preservation in rectal cancer. Against the motion.

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1 This house believes multiparametric MRI is the holy grail for organ preservation in rectal cancer Against the motion Karin Haustermans

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3 A high sensitivity means very few false negatives: no ccr but a pcr A high specificity means very few false positives: ccr but no pcr

4 Conventional MRI for restaging of locally advanced rectal cancer Zhao et al. Dis Colon Rectum Mar;57(3): Meta-analysis 24 studies 739 patients Very low sensitivity to predict pcr! Identifying pt0 rectal cancer by MRI is not reliable

5 DCE MRI for restaging of locally advanced rectal cancer Dijkhoff et al. Eur J Radiol Oct;95: Systematic review: 19 studies, 367 patients High Ktrans pre-crt correlates with complete/good response BUT The pre-crt Ktrans reported varied substantially ( ) between studies A reduction in Ktrans after CRT is associated with response

6 DW MRI for restaging of locally advanced rectal cancer Joye et al. Radiother Oncol 2014;113(2): Systematic review: 14 studies, 856 patients Parameter N pcr Sens Spec PPV NPV Accuracy DWI ADC pre VDWI pre ADC post ΔADC post (%) VDWI post ΔVDWI post (%) qualitative QUOTE FROM THE DISCUSSION: Unfortunately, MRI lacks the specificity and PPV needed to safely select patients for a wait and see policy

7 Radiomics: the Holy Grail? T2, DWI, DCE 48 patients Single center No validation set T2 and DWI 152 and 70 patients Single center Low pcr T2 114 patients Single center No validation set AUC = 0.93 Nie et al. Clin Cancer Res Nov 1;22(21): Liu et al. Clin Cancer Res. 2017; 23(23): Horvat et al. Radiol. 2018; 287(3):

8 Joye et al. Radiother Oncol Jul;124(1): patients ypt0-1n0: 22 patients

9 Joye et al. Radiother Oncol Jul;124(1): PET DWI blood tissue Adapted threshold SUV, volume, TLG Correction for BGL 6 b-values: s/mm² ROI on b0 ADC and T2-volumetry Multiplex ELISA Inflammatory markers Micro-array analysis

10 Legend CI=Combo imaging EL=ELISA MA=Microarray 12=T1 and T2 only 13=T1 and T3 only Joye et al. Radiother Oncol Jul;124(1):

11 Joye et al. Radiother Oncol Jul;124(1): AUC 0.81 ± 0.03 AUC 0.83 ± 0.03 Using a minimum PPV of 80% resulted in prediction of ypt0-1n0 with 75% sensitivity, 94% specificity and a NPV of 92% Model CI13 selected for the Leuven Organ Preservation Trial

12 Validated MR-based model for the prediction of the response to chemoradiotherapy Bulens et al. Radiother Oncol Mar;126(3): AUC 0,88 Model based on 4 parameters: T2: Volume% & Sphere_post DWI: ADC_avg_post & ADCratio_avg Development cohort (Leuven, n = 85) Validation cohort (Utrecht, n = 55) AUC 0,88 At a positive predictive value of at least 80%, this model showed a sensitivity of 68% and a specificity of 94%.

13 Validated MR-based model for the prediction of the response to chemoradiotherapy Bulens et al. Radiother Oncol Mar;126(3): AUC 0,88 EXPERTISE! Model based on 4 parameters: T2: Volume% & Sphere_post DWI: ADC_avg_post & ADCratio_avg AUC 0,88 Development cohort (Leuven, n = 85) Validation cohort (Utrecht, n = 55) At a positive predictive value of at least 80%, this model showed a sensitivity of 68% and a specificity of 94%.

14 The biological probe

15 Maas et al. Ann Surg Oncol Nov;22(12): patients Clinical assessment: AUC 0,88 All: AUC 0,89 Clinical assessment: sens 53%; spec 97% All: sens 71%; spec 97%

16 Habr-Gama et al. Dis Col Rect ;53(12): ccr = absence of positive signs of residual disease 1. Positive sign of incomplete clinical response: Residual deep ulceration +/- necrotic center (A) Superficial ulcer, irregularity (B) 2. To be considered as incomplete clinical response: Any palpable nodule, defined by DRE, even in presence of mucosal integrity (C) Any significant stenosis impeding the rigid proctoscope from sliding through A B C

17 This house believes multiparametric MRI is the holy grail for organ preservation in rectal cancer Against the motion The low specificity means residual tumor while MRI predicted a pcr The high sensitivity means a potential valuable tool to deselect patients for organ preservation strategies

18 The story of Lohengrin, son of Parcival, knight of the Round Table and guard of the holy grail He came to save his princess! Opera by Wagner, 1848

19 And married her so that she became Regina, the Queen of MRI!

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