Abstract
BackgroundTo evaluate the diagnostic performance of diffusion kurtosis imaging (DKI) for distinguishing different histopathological subtypes and grades of rectal carcinoma and to compare DKI with conventional diffusion-weighted imaging (DWI).MethodsThis prospective study involved 132 patients with rectal carcinoma, comprising 116 with adenocarcinoma not otherwise specified (AC) and 16 with mucinous carcinoma (MC). High spatial resolution magnetic resonance (MR) and DKI sequences (b values of 0, 600, 1000, 1500 and 2000 s/mm2) were performed for pretreatment evaluation. The mean kurtosis (MK) and mean diffusivity (MD) from DKI and the apparent diffusion coefficient (ADC) from DWI were measured by two experienced radiologists. The Mann-Whitney U test was used to evaluate different histopathological subtypes and grades. Receiver operating characteristic (ROC) curve analyses were performed to compare the diagnostic ability of different quantitative parameters.ResultsThe MD and ADC values were significantly higher for MC than for AC (1.94 ± 0.51 vs. 1.33 ± 0.02 and 1.26 ± 0.64 vs. 0.92 ± 0.01, respectively; P < 0.001). The MK values were significantly lower for MC than for AC (0.66 ± 0.02 vs. 0.93 ± 0.09, P < 0.001). The MK and MD values demonstrated higher sensitivity (94%, both) and specificity (96, 93%, respectively) than the ADC values. However, all the parameters derived from both DKI and DWI showed no significant differences between different histological grades.Conclusions DKI is a more valuable imaging biomarker than conventional DWI for differentiating MC from AC. However, it is still debatable whether DKI is useful for distinguishing different histological grades.
Highlights
To evaluate the diagnostic performance of diffusion kurtosis imaging (DKI) for distinguishing different histopathological subtypes and grades of rectal carcinoma and to compare DKI with conventional diffusionweighted imaging (DWI)
148 patients were included in the study at the first. 16 patients were excluded for satisfying one of the following exclusion criteria: (1) pathological diagnosis other than rectal carcinoma; (2) neoadjuvant therapy administered before magnetic resonance (MR) examination; (3) insufficiently large parenchymal area in the tumor to select regions of interest (ROIs); and (4) unsatisfactory image quality with serious artifact
Comparison between adenocarcinoma not otherwise specified (AC) and unaffected rectal wall The mean diffusivity (MD) and apparent diffusion coefficient (ADC) values were significantly lower in AC than in unaffected rectal wall (1.33 ± 0.02 vs. 2.20 ± 0.34, P < 0.001 for MD; 0.92 ± 0.01 vs. 1.59 ± 0.03, P < 0.001 for ADC)
Summary
To evaluate the diagnostic performance of diffusion kurtosis imaging (DKI) for distinguishing different histopathological subtypes and grades of rectal carcinoma and to compare DKI with conventional diffusionweighted imaging (DWI). Functional MR imaging, such as diffusion-weighted imaging (DWI), has been widely regarded as a promising tool for preoperative assessment of rectal carcinoma. This imaging modality can provide information on a molecular level in addition to anatomical information [11,12,13,14]. There are few studies on DKI for differentiating histopathological subtypes and grades of rectal carcinoma, especially for MC
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