Diffusion‐weighted imaging: Apparent diffusion coefficient histogram analysis for detecting pathologic complete response to chemoradiotherapy in locally advanced rectal cancer

Abstract

Purpose: To investigate the usefulness of apparent diffusion coefficient (ADC) values derived from histogram analysis of the whole rectal cancer as a quantitative parameter to evaluate pathologic complete response (pCR) on preoperative magnetic resonance imaging (MRI). Materials and Methods: We enrolled a total of 86 consecutive patients who had undergone surgery for rectal cancer after neoadjuvant chemoradiotherapy (CRT) at our institution between July 2012 and November 2014. Two radiologists who were blinded to the final pathological results reviewed post-CRT MRI to evaluate tumor stage. Quantitative image analysis was performed using T 2 -weighted and diffusion-weighted images independently by two radiologists using dedicated software that performed histogram analysis to assess the distribution of ADC in the whole tumor. Results: After surgery, 16 patients were confirmed to have achieved pCR (18.6%). All parameters from pre-and post-CRT ADC histogram showed good or excellent agreement between two readers. The minimum, 10th, 25th, 50th, and 75th percentile and mean ADC from post-CRT ADC histogram were significantly higher in the pCR group than in the non-pCR group for both readers. The 25th percentile value from ADC histogram in post-CRT MRI had the best diagnostic performance for detecting pCR, with an area under the receiver operating characteristic curve of 0.796. Conclusion: Low percentile values derived from the ADC histogram analysis of rectal cancer on MRI after CRT showed a significant difference between pCR and non-pCR groups, demonstrating the utility of the ADC value as a quantitative and objective marker to evaluate complete pathologic response to preoperative CRT in rectal cancer.

Measuring the apparent diffusion coefficient in primary rectal tumors: is there a benefit in performing histogram analyses?

“…This was confirmed in another study by Cho et al who reported significantly different 10th and 25th percentile values between responders and non-responders with better diagnostic performance compared to mean ADC [9]. However, similar to the findings of our current study, Choi et al find no benefit in any of the ADC or histogram metrics for pre-treatment prediction of response [10]. …”

“…In addition, adding histogram analysis provides information about the distribution of ADC values within the tumor, which can potentially offer valuable additional insights into tumor structure and heterogeneity. This information could be of added benefit to predict response and prognosis, as has been suggested by previous authors [9, 10]. …”

“…Nougaret et al reported that histogram metrics did not add to median ADC values for the assessment of rectal tumor response after CRT [19]. Choi et al found some promising results after CRT, with significant differences between poor and good responders after CRT for several histogram parameters (minimum ADC, 10th, 25th, 50th, and 75th percentiles) [10]. This was confirmed in another study by Cho et al who reported significantly different 10th and 25th percentile values between responders and non-responders with better diagnostic performance compared to mean ADC [9].…”

Deep Learning for Fully-Automated Localization and Segmentation of Rectal Cancer on Multiparametric MR

“…Furthermore ADC and histogram features derived from DWI-MRI have shown promise as quantitative imaging biomarkers for therapeutic outcome 4,5,9,10 . Most of these measures are calculated from regions of interest (ROI) of the tumour that are typically obtained after manual tumour segmentation by experienced readers.…”

Imaging in pleural mesothelioma: A review of the 12th International Conference of the International Mesothelioma Interest Group

“…Histogram analysis demonstrates tumor heterogeneity and is the foundation for DWI as a biomarker [36][37]. Moreover, these findings suggest that DWI could be a useful tool for personalized care in mesothelioma patients; when a second-line option becomes clinically available (currently a highly unmet need), this type of therapy response evaluation will become especially crucial.…”