Value of diffusion-weighted MRI and apparent diffusion coefficient measurements for predicting the response of locally advanced rectal cancer to neoadjuvant chemoradiotherapy

Abstract

DW-MRI may have a significant role in the restaging and in the evaluation of post-CRT response of locally advanced rectal cancer. Quantitative analysis of DWI through ADC map may result in a promising noninvasive tool to evaluate the response to therapy.

Response of locally advanced rectal cancer (LARC) to radiochemotherapy: DW-MRI and multiparametric PET/CT in correlation with histopathology

“…Although our results are concordant with those reported by Kim et al [32], previous studies could determine an optimal cutoff value for postRCT ADCmean to predict good re sponders with a sensitivity of 77.3-88.4 %, specificity of 66.7 % and accuracy of 80.7-87 % [13,17,18,[20][21][22][23]36]. The ∆ADCmean showed a sensitivity of 63.4-72 % and specificity of 66.7-82 % to predict complete response [13,21,36]. Several methodological issues could explain these discrepancies [37].…”

Diffusion-weighted imaging in rectal cancer: current applications and future perspectives

“…Regardless of the definition of response used in these reports (i.e. good or complete response), all studies reported an increase in mean tumour ADC after CRT, 36,39,42,49,[51][52][53][54][55][56][57][58] which is thought to be due to radiation-induced cellular damage and necrosis. 91,92 The disruption of cell membranes reduces the diffusion restriction and therefore increases the ADC.…”

“…Both the final post-CRT ADC and the relative increase in ADC (∆ADC%) were typically higher in the favourable response groups, with statistically significant results in the majority of studies . 36,42,[52][53][54][55][57][58][59][60][61][62][63][64][65][66][67][68][69][70][78][79][80][82][83][84] In addition, several studies found significantly higher pre-CRT ADC values in the unfavourable response groups, 42,[53][54][55][56][63][64][65][66][72][73][74]77,78 although a similar number of studies did not find a significant difference in pre-CRT ADC between response groups. 51,52,58,59,61,62,64,[67][68]…”

“…diffusion coefficient; CRT, chemoradiotherapy. Statistically significant results (p < 0.05) are printed in bold Note: cT = clinical T-stage, ypT = histopathological T-stage, TRG = tumour regression grade, RCRG = rectal cancer regression grade, ypCR/pCR = pathological complete response, ypPR = pathological partial response, ypSD = pathological stable diseaseStudies53,60 used Dworak's TRG54 ; used the Wheeler's RCRG,55 used Ryan's TRG,[56][57][58][59][61][62][63][64][65][66][67][68] used Mandard's TRG a =absolute difference in ADC between pre-and post-treatment scan; *=reported as ADCratio = (ADCpost -ADCpre)/ADCpre; NS = not significant; " " same as above…”

Is it better to include necrosis in apparent diffusion coefficient (ADC) measurements? The necrosis/wall ADC ratio to differentiate malignant and benign necrotic lung lesions: Preliminary results

“…The ADC value offers quantitative examination and provides benign and malignant discrimination. Low ADC values reflect dense cellular structures and aggressiveness of the tumor . Additionally, cellular proliferation rate, size of nucleus, intracellular macromolecules, nucleus‐cytoplasm rate, and size of the extracellular matrix may affect the value of ADC .…”