Predictive role of diffusion-weighted MRI in the assessment of response to total neoadjuvant therapy in locally advanced rectal cancer

Franco Iafrate; Fabio Ciccarelli; Giorgio Maria Masci; Damiano Grasso; Francesco Marruzzo; Francesca De Felice; Vincenzo Tombolini; Giancarlo D'Ambrosio; Fabio Massimo Magliocca; Enrico Cortesi; Carlo Catalano

doi:10.1007/s00330-022-09086-7

Predictive role of diffusion-weighted MRI in the assessment of response to total neoadjuvant therapy in locally advanced rectal cancer

Eur Radiol. 2023 Feb;33(2):854-862. doi: 10.1007/s00330-022-09086-7. Epub 2022 Aug 18.

Affiliations

¹ Department of Radiological, Oncological and Pathological Sciences, Policlinico Umberto I, Sapienza University of Rome, Viale Regina Elena 324, 00161, Rome, Italy. francoiafrate@gmail.com.
² Department of Radiological, Oncological and Pathological Sciences, Policlinico Umberto I, Sapienza University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
³ Department of Radiotherapy, Policlinico Umberto I, Sapienza University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
⁴ Department of General Surgery, Surgical Specialties and Organ Transplantation, Policlinico Umberto I, Sapienza University of Rome, Viale del Policlinico 155, 00161, Rome, Italy.

PMID: 35980431
DOI: 10.1007/s00330-022-09086-7

Abstract

Objective: To investigate the predictive role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the assessment of response to total neoadjuvant therapy (TNT) in patients with locally advanced rectal cancer (LARC).

Methods: In this single-center retrospective study, patients with LARC who underwent staging MRI and TNT were enrolled. MRI-based staging, tumor volume, and DWI-ADC values were analyzed. Patients were classified as complete responders (pCR) and non-complete responders (non-pCR), according to post-surgical outcome. Pre-treatment ADC values were compared to pathological outcome, post-treatment downstaging, and reduction of tumor volume. The diagnostic accuracy of DWI-ADC in differentiating between pCR and non-pCR groups was calculated with receiver operating characteristic (ROC) analysis.

Results: A total of 36 patients were evaluated (pCR, n = 20; non-pCR, n = 16). Pre-treatment ADC values were significantly different between the two groups (p = 0.034), while no association was found between pre-TNT tumor volume and pathological response. ADC values showed significant correlations with loco-regional downstaging after therapy (r = -0.537, p = 0.022), and with the reduction of tumor volume (r = -0.480, p = 0.044). ADC values were able to differentiate pCR from non-pCR patients with a sensitivity of 75% and specificity of 70%.

Conclusions: ADC values on pre-treatment MRI were strongly associated with the outcome in patients with LARC, both in terms of pathological response and in loco-regional downstaging after TNT, suggesting the use of DW-MRI as a potential predictive tool of response to therapy.

Key points: • ADC values of pre-TNT MRI examinations of patients with LARC were significantly associated with a pathological complete response (pCR) and with post-treatment regression of TNM staging. • An ADC value of 1.042 ×10^-3 mm²/s was found to be the optimal cutoff value for discriminating between pCR and non-pCR patients, with a sensitivity of 75% and specificity of 70%. • DW-MRI proved to have a potential predictive role in the assessment of response to therapy in patients with LARC, throughout the analysis of ADC map values.

Keywords: Diffusion magnetic resonance imaging; Neoadjuvant therapy; Rectal neoplasms.

MeSH terms

Chemoradiotherapy
Diffusion Magnetic Resonance Imaging* / methods
Humans
Magnetic Resonance Imaging
Neoadjuvant Therapy
Rectal Neoplasms* / drug therapy
Rectal Neoplasms* / therapy
Retrospective Studies
Treatment Outcome