Diffusion-Weighted Imaging Reflects Tumor Grading and Microvascular Invasion in Hepatocellular Carcinoma

Abstract

<b><i>Background:</i></b> To date, there are inconsistent data about relationships between diffusion-weighted imaging (DWI) and tumor grading/microvascular invasion (MVI) in hepatocellular carcinoma (HCC). Our purpose was to systematize the reported results regarding the role of DWI in prediction of tumor grading/MVI in HCC. <b><i>Method:</i></b> MEDLINE library, Scopus, and Embase data bases were screened up to December 2019. Overall, 29 studies with 2,715 tumors were included into the analysis. There were 20 studies regarding DWI and tumor grading, 8 studies about DWI and MVI, and 1 study investigated DWI, tumor grading, and MVI in HCC. <b><i>Results:</i></b> In 21 studies (1,799 tumors), mean apparent diffusion coefficient (ADC) values (ADC<sub>mean</sub>) were used for distinguishing HCCs. ADC<sub>mean</sub> of G1–3 lesions overlapped significantly. In 4 studies (461 lesions), minimum ADC (ADC<sub>min</sub>) was used. ADC<sub>min</sub> values in G1/2 lesions were over 0.80 × 10<sup>−3</sup> mm<sup>2</sup>/s and in G3 tumors below 0.80 × 10<sup>−3</sup> mm<sup>2</sup>/s. In 4 studies (241 tumors), true diffusion (<i>D</i>) was reported. A significant overlapping of <i>D</i> values between G1, G2, and G3 groups was found. ADC<sub>mean</sub> and MVI were analyzed in 9 studies (1,059 HCCs). ADC<sub>mean</sub> values of MIV+/MVI− lesions overlapped significantly. ADC<sub>min</sub> was used in 4 studies (672 lesions). ADC<sub>min</sub> values of MVI+ tumors were in the area under 1.00 × 10<sup>−3</sup> mm<sup>2</sup>/s. In 3 studies (227 tumors), <i>D</i> was used. Also, <i>D</i> values of MVI+ lesions were predominantly in the area under 1.00 × 10<sup>−3</sup> mm<sup>2</sup>/s. <b><i>Conclusion:</i></b> ADC<sub>min</sub> reflects tumor grading, and ADC<sub>min</sub> and <i>D</i> predict MVI in HCC. Therefore, these DWI parameters should be estimated for every HCC lesion for pretreatment tumor stratification. ADC<sub>mean</sub> cannot predict tumor grading/MVI in HCC.

Revisiting Surgical Strategies for Hepatocellular Carcinoma With Microvascular Invasion

“…However, with increasing recognition of MVI and its prognostic value on surgical outcomes of HCC, preoperative MVI prediction systems for surgical decision making have become a hot topic in recent researches. In recent years, some studies have reported the possibility of imaging findings to predict the MVI of HCC (24)(25)(26)(27). However, it still has a limited capacity to detect MVI and the precise detection of MVI needs further histological identification (28).…”

The Role of Non-Gaussian Models of Diffusion Weighted MRI in Hepatocellular Carcinoma: A Systematic Review

“…To our knowledge, this is the first systematic review aiming at summarizing the role of non-Gaussian diffusion MRI models in HCC. To date, systematic studies were performed on conventional diffusion metrics for HCC detection and prognosis [15,90,91]. Surov et al performed a meta-analysis to assess the role of DWI in prediction of tumor grading and MVI in HCC, also including D in the investigated metrics [15].…”

“…To date, systematic studies were performed on conventional diffusion metrics for HCC detection and prognosis [15,90,91]. Surov et al performed a meta-analysis to assess the role of DWI in prediction of tumor grading and MVI in HCC, also including D in the investigated metrics [15]. Wu et al performed a metaanalysis evaluating the IVIM model in differentiating focal liver lesions, also including HCC [78].…”

“…Although several studies used the mono-exponential DWI model in HCC [12][13][14][15][16][17], this model is based on assumptions that are often inaccurate since in vivo water diffusion is more complex, may be anisotropic, and often presents non-Gaussian behavior. Given the above, ADC value may not be associated with the true tissue characteristics.…”

68Ga-DOTATATE PET/CT and MRI with Diffusion-Weighted Imaging (DWI) in Short- and Long-Term Assessment of Tumor Response of Neuroendocrine Liver Metastases (NELM) Following Transarterial Radioembolization (TARE)

“…Attention was paid to excluding structures close to the rim of the lesion to avoid partial volume effects. These ROIs were transferred to the same slice of the ADCmap to calculate intralesional ADC values including minimal (ADCmin) and mean (ADCmean) ADC (below noted as 10 −3 mm 2 /s), as these reflect the most commonly assessed ADC values in current literature [23]. In addition, ADC mean values of tumor-free liver were assessed by drawing circular ROIs, as large as possible.…”