Tumour ADC measurements in rectal cancer: effect of ROI methods on ADC values and interobserver variability.

D.M. Lambregts, G.L. Beets, M. Maas, L. Curvo Semedo, A.G. Kessels, T. Thywissen, R.G. Beets Tan

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

OBJECTIVES: To assess the influence of region of interest (ROI) size and positioning on tumour ADC measurements and interobserver variability in patients with locally advanced rectal cancer (LARC). METHODS: Forty-six LARC patients were retrospectively included. Patients underwent MRI including DWI (b0,500,1000) before and 6-8 weeks after chemoradiation (CRT). Two readers measured mean tumour ADCs (pre- and post-CRT) according to three ROI protocols: whole-volume, single-slice or small solid samples. The three protocols were compared for differences in ADC, SD and interobserver variability (measured as the intraclass correlation coefficient; ICC). RESULTS: ICC for the whole-volume ROIs was excellent (0.91) pre-CRT versus good (0.66) post-CRT. ICCs were 0.53 and 0.42 for the single-slice ROIs versus 0.60 and 0.65 for the sample ROIs. Pre-CRT ADCs for the sample ROIs were significantly lower than for the whole-volume or single-slice ROIs. Post-CRT there were no significant differences between the whole-volume ROIs and the single-slice or sample ROIs, respectively. The SDs for the whole-volume and single-slice ROIs were significantly larger than for the sample ROIs. CONCLUSIONS: ROI size and positioning have a considerable influence on tumour ADC values and interobserver variability. Interobserver variability is worse after CRT. ADCs obtained from the whole tumour volume provide the most reproducible results. Key Points * ROI size and positioning influence tumour ADC measurements in rectal cancer * ROI size and positioning influence interobserver variability of tumour ADC measurements * ADC measurements of the whole tumour volume provide the most reproducible results * Tumour ADC measurements are more reproducible before, rather than after, chemoradiation treatment * Variations caused by ROI size and positioning should be taken into account when using ADC as a biomarker for tumour response.
Original languageEnglish
Pages (from-to)2567-2574
Number of pages8
JournalEuropean Radiology
Volume21
Issue number12
DOIs
Publication statusPublished - Dec 2011

Keywords

  • Diffusion magnetic resonance imaging
  • Rectal neoplasms
  • Observer variation
  • Methodology
  • Apparent diffusion coefficient
  • APPARENT DIFFUSION-COEFFICIENT
  • CHEMORADIATION THERAPY
  • IMAGING BIOMARKER
  • RADIATION-THERAPY
  • PREDICTION
  • CARCINOMA
  • MRI
  • CHEMOTHERAPY
  • CHEMORADIOTHERAPY

Cite this

Lambregts, D. M., Beets, G. L., Maas, M., Curvo Semedo, L., Kessels, A. G., Thywissen, T., & Beets Tan, R. G. (2011). Tumour ADC measurements in rectal cancer: effect of ROI methods on ADC values and interobserver variability. European Radiology, 21(12), 2567-2574. https://doi.org/10.1007/s00330-011-2220-5