Role of Quantitative Dynamic Contrast-Enhanced MRI in Evaluating Regional Lymph Nodes With a Short-Axis Diameter of Less Than 5 mm in Rectal Cancer

AJR Am J Roentgenol. 2019 Jan;212(1):77-83. doi: 10.2214/AJR.18.19866. Epub 2018 Oct 24.

Abstract

Objective: The aim of this study was to discriminate metastatic from nonmetastatic regional lymph nodes (LNs) with short-axis diameters of less than 5 mm in rectal cancer using quantitative parameters derived from dynamic contrast-enhanced (DCE) MRI.

Subjects and methods: Sixty-five LNs from 122 patients were evaluated, including malignant LNs (n = 27) and benign LNs (n = 38). The following parameters were assessed: the forward volume transfer constant (Ktrans), reverse volume transfer constant (kep), fractional extravascular extracellular space volume (Ve), short-axis diameter, long-axis diameter, and short- to long-axis diameter ratio. ROC curves were used to analyze statistically significant parameters.

Results: Metastatic LNs exhibited a lower Ktrans than did nonmetastatic LNs (p < 0.001), but the other parameters were not significantly different between the two groups. The AUC of the Ktrans was 0.732, with a 95% CI of 0.610-0.854, and the diagnostic cutoff value was 0.088 min-1 (sensitivity, 60.5%; specificity, 81.5%).

Conclusion: Ktrans had moderate diagnostic performance in assessing small regional LNs in rectal cancer and appears to be a useful predictor when distinguishing malignant LNs from benign LNs only by morphology is difficult.

Keywords: MRI; lymph node; perfusion; pharmacokinetics; rectal cancer.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biopsy
  • Contrast Media
  • Diagnosis, Differential
  • Gadolinium DTPA
  • Humans
  • Image Interpretation, Computer-Assisted
  • Lymphatic Metastasis / diagnostic imaging*
  • Lymphatic Metastasis / pathology*
  • Magnetic Resonance Imaging / methods*
  • Middle Aged
  • Neoplasm Staging
  • Prospective Studies
  • Rectal Neoplasms / pathology*
  • Sensitivity and Specificity

Substances

  • Contrast Media
  • Gadolinium DTPA