Comparison of reduced field-of-view diffusion-weighted imaging (DWI) and conventional DWI techniques in the assessment of rectal carcinoma at 3.0T: Image quality and histological T staging

J Magn Reson Imaging. 2018 Apr;47(4):967-975. doi: 10.1002/jmri.25814. Epub 2017 Jul 10.

Abstract

Purpose: To compare image quality (IQ) of reduced field-of-view (rFOV) and full FOV (fFOV) diffusion-weighted imaging (DWI) sequences at 3T, with histological T staging of rectal cancer as a reference standard.

Materials and methods: In all, 81 patients with rectal cancer received magnetic resonance (MR) scans (3.0T), including both rFOV and fFOV DWI sequences. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantitatively evaluated using the paired t-test. Two radiologists independently assessed subjective IQ parameters, including image sharpness, distortion, artifacts, lesion conspicuity, and overall subjective IQ of both sequences. The Wilcoxon signed rank test was used to compare subjective IQ scores and tumor apparent diffusion coefficients (ADCs) between DWI sequences. Spearman correlation analysis was used to correlate ADC values and corresponding T staging of rectal cancer.

Results: CNR was significantly higher in rFOV DWI than in fFOV DWI (7.15 ± 2.77 vs. 5.39 ± 2.08, P < 0.001). SNR was significantly higher in rFOV DWI than in fFOV DWI (44.17 ± 11.01 vs. 34.76 ± 13.30, P < 0.001). The subjective IQ parameters of rFOV DWI sequence were rated superior to those of fFOV DWI sequence by both readers (P < 0.001). No significant differences between mean tumor ADC values of both sequences (0.991 ± 0.121 vs. 0.100 ± 0.126 × 10-3 mm2 /s, P = 0.617) were noted. Apart from T1 stage, T staging of rectal cancer was inversely correlated with ADC values of rFOV DWI (r = -0.688, P < 0.001) and fFOV DWI sequences (r = -0.641, P < 0.001).

Conclusion: The rFOV DWI sequence provided significantly better IQ and lesion conspicuity than the fFOV DWI sequence. In addition, rFOV and fFOV DWI sequences can be used in evaluation of histological T staging of rectal cancer.

Level of evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:967-975.

Keywords: diffusion-weighted imaging; field-of-view; histological T staging; magnetic resonance imaging; rectal cancer.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Diffusion Magnetic Resonance Imaging / methods*
  • Female
  • Humans
  • Image Interpretation, Computer-Assisted / methods*
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Rectal Neoplasms / diagnostic imaging*
  • Rectal Neoplasms / pathology*
  • Rectum / diagnostic imaging
  • Rectum / pathology
  • Reproducibility of Results
  • Retrospective Studies
  • Sensitivity and Specificity
  • Young Adult