Abstract
PurposeDiffusion-weighted imaging (DWI) plays an important role in the preoperative assessment of gliomas; however, the diagnostic performance of histogram-derived parameters from mono-, bi-, and stretched-exponential DWI models in the grading of gliomas has not been fully investigated. Therefore, we compared these models’ ability to differentiate between high-grade and low-grade gliomas.MethodsThis retrospective study included 22 patients with diffuse gliomas (age, 23–74 years; 12 males; 11 high-grade and 11 low-grade gliomas) who underwent preoperative 3 T-magnetic resonance imaging from October 2014 to August 2019. The apparent diffusion coefficient was calculated from the mono-exponential model. Using 13 b-values, the true-diffusion coefficient, pseudo-diffusion coefficient, and perfusion fraction were obtained from the bi-exponential model, and the distributed-diffusion coefficient and heterogeneity index were obtained from the stretched-exponential model. Region-of-interests were drawn on each imaging parameter map for subsequent histogram analyses.ResultsThe skewness of the apparent diffusion, true-diffusion, and distributed-diffusion coefficients was significantly higher in high-grade than in low-grade gliomas (0.67 ± 0.67 vs. − 0.18 ± 0.63, 0.68 ± 0.74 vs. − 0.08 ± 0.66, 0.63 ± 0.72 vs. − 0.15 ± 0.73; P = 0.0066, 0.0192, and 0.0128, respectively). The 10th percentile of the heterogeneity index was significantly lower (0.77 ± 0.08 vs. 0.88 ± 0.04; P = 0.0004), and the 90th percentile of the perfusion fraction was significantly higher (12.64 ± 3.44 vs. 7.14 ± 1.70%: P < 0.0001), in high-grade than in low-grade gliomas. The combination of the 10th percentile of the true-diffusion coefficient and 90th percentile of the perfusion fraction showed the best area under the receiver operating characteristic curve (0.96).ConclusionThe bi-exponential model exhibited the best diagnostic performance for differentiating high-grade from low-grade gliomas.
Highlights
Gliomas are the most common primary intracranial neoplasms and have various histological grades that reflect malignancy or aggressiveness, according to the World Health Organization (WHO) classification [1]
For diffusion-related parameters, the skewness of apparent diffusion coefficient (ADC) (ADCskw), Dskw, and DDCskw were significantly higher in high-grade gliomas (HGGs) than in low-grade gliomas (LGGs) (0.67 ± 0.67 vs. − 0.18 ± 0.63, 0.68 ± 0.74 vs. − 0.08 ± 0.66, 0.63 ± 0.72 vs. − 0.15 ± 0.73; P = 0.007, 0.002, and 0.01, respectively)
The 90th percentile of the perfusion fraction (f90) was significantly higher in HGGs than that in LGGs (12.64 ± 3.44 vs. 7.14 ± 1.70%; P < 0.001)
Summary
Gliomas are the most common primary intracranial neoplasms and have various histological grades that reflect malignancy or aggressiveness, according to the World Health Organization (WHO) classification [1]. HGGs misdiagnosed as LGGs are treated less aggressively than necessary, and vice versa. Diffusion-weighted imaging (DWI) provides useful imaging biomarkers for grading gliomas, enabling the quantitative assessment of tumor characteristics without tracer injections. The apparent diffusion coefficient (ADC), which is a useful biomarker reflecting cellular density, is conventionally calculated using two b-values (0 and 1000 s/mm2) [3]. It has good diagnostic performance in differentiating HGGs from LGGs [3], but there is substantial overlap [4, 5]. Using the ADC in the differential diagnosis may be an oversimplification; it assumes that the only underlying mechanism of observed signal decay is the diffusive motion of water molecules
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