Quantitative T2*-Weighted Imaging and Reduced Field-of-View Diffusion-Weighted Imaging of Rectal Cancer: Correlation of R2* and Apparent Diffusion Coefficient With Histopathological Prognostic Factors

Abstract

PurposeTo assess T2*-weighted imaging (T2*WI) and reduced field-of-view diffusion-weighted Imaging (rDWI) derived parameters and their relationships with histopathological factors in patients with rectal cancer.MethodsFifty-four patients with pathologically-proven rectal cancer underwent preoperative T2*-weighted imaging and rDWI in this retrospective study. R2* values from T2*-weighted imaging and apparent diffusion coefficient (ADC) values from rDWI were compared in terms of different histopathological prognostic factors using student’s t-test or Mann-Whitney U-test. The correlations of R2* and ADC with prognostic factors were assessed by Spearman correlation analysis. The diagnostic performances of R2* and ADC were analyzed by receiver operating characteristic curves (ROC) separately and jointly.ResultsSignificant positive correlation was found between R2* values and T stage, lymph node involvement, histological grades, CEA level, the presence of EMVI and tumor deposit (r = 0.374 ~ 0.673, p = 0.000–0.006), with the exception of CA19-9 level, CRM status and tumor involvement in the circumference lumen (TIL). Meanwhile, ADC values negatively correlated with almost all the prognostic factors (r = −0.588 to −0.299, p = 0.000–0.030), except CA19-9 level. The AUC range was 0.724–0.907 for R2* and 0.674–0.887 for ADC in discrimination of different prognostic factors. While showing the highest AUC of 0.913 (0.803–1.000) in differentiation of T stage, combination of R2* and ADC with reference to different prognostic factors did not significantly improve the diagnostic performance in comparison with individual R2*/ADC parameter.ConclusionsR2* and ADC were associated with important histopathological prognostic factors of rectal cancer. R2* might act as additional quantitative imaging marker for tumor characterization of rectal cancer.

Diagnostic performance of synthetic magnetic resonance imaging in the prognostic evaluation of rectal cancer

“…The quantitative T2 relaxation time is widely used in the brain, breast, kidney, and prostate (16,(25)(26)(27). The R2* value was also closely related to histopathological prognostic factors in RC by T2*-weighted imaging (28), which was consistent with the present result. Previous results on the association between T2 value and prognosis factors in other diseases have been consistent (24,27,29).…”

Assessing the histopathological features of rectal adenocarcinoma with chemical shift–encoded sequence (CSE)-MRI and diffusion-weighted imaging (DWI)

“…R2* has been found to reflect the liver iron content and tumor hypoxia of breast cancer ( 33 , 34 ). Previous reported ( 14 , 15 ) demonstrated that R2* correlated with the status of deoxyhemoglobin and blood oxygenation, with the increased level of blood deoxyhemoglobin could potentially leading to elevated R2* ( 35 ). Tumors with advanced stage lead to a more hypoxic microenvironment due to the rapid proliferation of tumor cells and tumor development ( 36 , 37 ), resulting in increased content of deoxyhemoglobin and R2* values.…”

“…Furthermore, diffusion-weighted imaging (DWI) is often used for the preoperative assessment of TNM (Tumor Node Metastasis) staging of rectal adenocarcinoma and is helpful for the discrimination of histological prognostic factors. However, DWI often fails to distinguish some histological features (15,16). Furthermore, previous studies suggest that apparent diffusion coefficient (ADC) measurements from DWI are not consistent with the utility of different b values (17)(18)(19).…”

“…Furthermore, the reconstruction of water-only, fat-only, and R2* images are also produced simultaneously with fat fraction images in a single acquisition. CSE-MRI R2* values have been used to measure liver iron content ( 13 ) and tumor hypoxia of breast cancer ( 14 ), and R2* values have been previously reported to reflect the status of deoxyhemoglobin and blood oxygenation ( 15 , 16 ). However, to date, no investigation has been performed that uses the CSE-MRI technique to quantify intratumoral fat content and R2*-related biochemical changes of rectal adenocarcinoma.…”

Semi-automatic tumor segmentation of rectal cancer based on functional magnetic resonance imaging

“…Multi echo T2*w imaging is a method that visualizes endogenous paramagnetic deoxyhemoglobin, which in breast cancer has been shown to correlate to tumor hypoxia [14] . In rectal cancer, the method has recently shown potential to provide a useful quantitative biomarker [15] .…”