MRI Evaluation of Rectal Cancer Lymph Node Staging Using Apparent Diffusion Coefficient

Ingrida Pikūnienė; Žilvinas Saladžinskas; Algidas Basevičius; Vestina Strakšytė; Justas Žilinskas; Rita Ambrazienė

doi:10.7759/cureus.45002

MRI Evaluation of Rectal Cancer Lymph Node Staging Using Apparent Diffusion Coefficient

Cureus. 2023 Sep 10;15(9):e45002. doi: 10.7759/cureus.45002. eCollection 2023 Sep.

Authors

Ingrida Pikūnienė¹, Žilvinas Saladžinskas², Algidas Basevičius¹, Vestina Strakšytė¹, Justas Žilinskas², Rita Ambrazienė³

Affiliations

¹ Department of Radiology, Hospital of Lithuanian University of Health Sciences Kauno Klinikos, Kaunas, LTU.
² Department of Surgery, Hospital of Lithuanian University of Health Sciences Kauno Klinikos, Kaunas, LTU.
³ Department of Oncology, Hospital of Lithuanian University of Health Sciences Kauno Klinikos, Kaunas, LTU.

Abstract

Introduction Colorectal cancer is the third most diagnosed cancer globally. Lymph node metastases significantly affect prognosis, emphasizing the importance of early detection and management. Despite significant advances in conventional MRI's role in staging, improvements in advanced functional imaging such as diffusion-weighted imaging (DWI) in identifying lymph node metastases persist. Objectives The aim is to evaluate the effectiveness of apparent diffusion coefficient (ADC) MRI in evaluating lymph node staging in rectal cancer. Patients and methods In a prospective study, 89 patients with stage II-III rectal cancer were grouped into two treatments: pre-operative FOLFOX4 chemotherapy and standard pre-operative chemoradiotherapy. All underwent 1.5T MRI, with T2-weighted and DWI sequences. A radiologist defined regions of interest on the tumor, lymph nodes, and intact rectal wall to calculate ADC values. Results Rectal cancer ADC's receiver operating characteristic curve had an area under the curve (AUC) of 0.688 (P < 0.001), with optimal ADC cutoff at 0.99 x 10-3 mm2/s (sensitivity: 75%, specificity: 83%). For lymph nodes, AUC was 0.508 (P < 0.001), with a cutoff of 0.9 x 10-3 mm2/s (sensitivity: 78%, specificity: 67%). No correlation between tumor and lymph node ADC values was observed. In chemotherapy patients, "healthy" inguinal lymph nodes had higher ADC values than affected ones pre-treatment (P = 0.001), a disparity fading post-treatment (P = 0.313). For chemoradiotherapy patients, the ADC difference persisted pre and post-treatment (P = 0.001). Conclusion The study of ADC-MRI showed different ADC values between tumors and lymph nodes and highlighted ADC differences between treatment groups. Notably, no correlation was observed between tumor and lymph node ADC values. However, differences were apparent when comparing "healthy" inguinal nodes with lymph nodes affected by cancer.

Keywords: apparent diffusion coefficient; diffusion-weighted imaging; lymph nodes; magnetic resonance imaging; rectal cancer.