Predicting locally advanced rectal cancer response to neoadjuvant therapy with 18F-FDG PET and MRI radiomics features

Eur J Nucl Med Mol Imaging. 2019 Apr;46(4):878-888. doi: 10.1007/s00259-018-4250-6. Epub 2019 Jan 13.

Abstract

Purpose: Pathological complete response (pCR) following neoadjuvant chemoradiotherapy or radiotherapy in locally advanced rectal cancer (LARC) is reached in approximately 15-30% of cases, therefore it would be useful to assess if pretreatment of 18F-FDG PET/CT and/or MRI texture features can reliably predict response to neoadjuvant therapy in LARC.

Methods: Fifty-two patients were dichotomized as responder (pR+) or non-responder (pR-) according to their pathological tumor regression grade (TRG) as follows: 22 as pR+ (nine with TRG = 1, 13 with TRG = 2) and 30 as pR- (16 with TRG = 3, 13 with TRG = 4 and 1 with TRG = 5). First-order parameters and 21 second-order texture parameters derived from the Gray-Level Co-Occurrence matrix were extracted from semi-automatically segmented tumors on T2w MRI, ADC maps, and PET/CT acquisitions. The role of each texture feature in predicting pR+ was assessed with monoparametric and multiparametric models.

Results: In the mono-parametric approach, PET homogeneity reached the maximum AUC (0.77; sensitivity = 72.7% and specificity = 76.7%), while PET glycolytic volume and ADC dissimilarity reached the highest sensitivity (both 90.9%). In the multiparametric analysis, a logistic regression model containing six second-order texture features (five from PET and one from T2w MRI) yields the highest predictivity in distinguish between pR+ and pR- patients (AUC = 0.86; sensitivity = 86%, and specificity = 83% at the Youden index).

Conclusions: If preliminary results of this study are confirmed, pretreatment PET and MRI could be useful to personalize patient treatment, e.g., avoiding toxicity of neoadjuvant therapy in patients predicted pR-.

Keywords: 18F-FDG PET/CT imaging; Locally advanced rectal cancer; Magnetic resonance imaging; Prediction of treatment response; Radiomics; Texture features.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Female
  • Fluorodeoxyglucose F18*
  • Humans
  • Image Processing, Computer-Assisted*
  • Magnetic Resonance Imaging*
  • Male
  • Multimodal Imaging*
  • Neoadjuvant Therapy*
  • Positron-Emission Tomography*
  • Rectal Neoplasms / diagnostic imaging*
  • Rectal Neoplasms / pathology
  • Rectal Neoplasms / therapy*

Substances

  • Fluorodeoxyglucose F18