The final study population consisted of 100 patients (female: 45,
male: 55) with a 104 lesions (77 malignant and 27 benign) (Table 1) and with a total 34 hypervascular malignant FLLs and 43 hypovascular malignat FLLs respectively.
Fig. 2
Fig. 2: Table reporting the demographic characteristics of patients and lesions numbers were reported.
References: Department of Radiology Ca'Foncello Regional Hospital (Treviso Italy)
The means of each ADC and IVIM derived quantitative parameters are reported in Table 2 and 3 (Fig 5 and Fig 6),
in Table 4 (Fig 7) are illustrated the results of ROC analysis.
The ADC mean and ADC median were significantly different between benign VS malignant lesions and hypervascular benign VS hypervascular malignant lesions,
with lower values in the malignant group.
In IVIM parameters,
the largest number of statistically significant differences were found in the groups of the benign VS malignant lesions,
but there were also significant differences between hypervascular benign VS hypervascular malignant lesions (D values) and hypovascular malignant VS hypervascular malignant lesions (f values and fDs values).
Among the IVIM parameters,
the mean values of the significantly different D values (mean,
median,
skewness and kurtosis) found between malignant and benign lesions were all lower in the malignant group and the mean values of the significantly different D values (mean and median) were also found lower in the malignant hypervascular lesion than in the hypervascular benign lesion group Fig. 3 .
Fig. 3: Fig 2: example of different D and ADC values between a benign focal liver lesion(FNH) and a malignant focal liver lesion(Lymphoma).
The values of D and ADC are significantly higher in the first group.
References: Department of Radiology Ca'Foncello Regional Hospital (Treviso Italy)
The mean values of the significantly different f values (std,
skewness and kurtosis) found between hypervascular and hypovascular malignant lesions were different: the skewness and kurtosis were lower in the hypovascular group,
the std was lower in the hypervascular group.
Moreover f value (entropy) was lower in the benign group than in the malignant group.
The mean values of the significantly different fDs values (mean,
median,
std and entropy) found between hypervascular and hypovascular malignant lesions were all lower in the malignant group Fig. 4 .
Fig. 4: Fig.3: example of the FDs mean value between a hypervascular (HCC) and a hypovascular malignant lesion (CCC).
The value of the hypovascular lesion is lower than the hypervascular lesion.
References: Department of Radiology Ca'Foncello Regional Hospital (Treviso Italy)
Ds values did not show a significant difference among the different groups except for median and entropy values between hypervascular and hypovascular malignant and here we can see lower value in the malignant group.
Fig. 5
Fig. 5: Table 2. The “p value” for each group comparison is shown. Significant values were in bold.
References: Department of Radiology Ca'Foncello Regional Hospital (Treviso Italy)
Fig. 6
Fig. 6: Table 3. Mean ± standard deviation values for ADC and each IVIM derived quantitative parameter are reported.
References: Department of Radiology Ca'Foncello Regional Hospital (Treviso Italy)
Fig. 7
Fig. 7: Table 4. The results of ROC analysis are reported.
References: Department of Radiology Ca'Foncello Regional Hospital (Treviso Italy)
The present study has found that ADC and D values are useful to differentiate benign Vs malignant FLLs and hypervascular Vs hypovascular FLLs.
The comparison of diagnostic performance between the D parameters and ADC in differentiating malignant tumours from benign lesion showed a slightly higher accuracy of the D values in predicting malignant tumours than ADC.
We found significant differences in cellular density parameters (ADC and true D) and not in the perfusion parameters.
Regarding the perfusion IVIM parameters (f,
Ds and fDs),
we observed significant values in the group of hypervascular vs hypovascular malignant lesions,
with a tendency to lower values in the hypovascular malignant lesions.
According with previous studies we found that Ds is an unstable and fluctuating value with an higher error in calculation,
but despite this,
in our study we also found some significant lower values (median and entropy) in the hypovascular malignant group.
The fDs (mean,
median,
std and entropy) values (the new parameter representing the quantity of blood flowing through a unit tissue for unit time) were significantly lower in hypovascular malignant lesions than in hypervascular malignant lesions.
Therefore,
based on our results,
we may suggest a possible correlation between perfusion parameters of the IVIM model representing microscopic perfusion characteristics of tissue and the classic perfusion pattern on dynamic imaging,
which might represent vascularity and permeability of tissue.
Thus,
IVIM-DWI derived perfusion parameters may reduce the clinical dependence on contrast-enhanced liver imaging,
therefore it can become a valid tool when contrast agent is contraindicated or when timing of the arterial phase imaging is ineffective.
Finally,
there are no significant elements related to the group of benign lesions (FNH vs Adenoma) probably that is due to the limited number of the lesions (only 5 Adenomas).
We utilized an IVIM model using a volumetric approach,
in the characterization of FLLs and to our knowledge there is no study published with this method.
(In the previous liver studies one or more regions of interest (ROI) at the most significant slice of the lesion where drew,
generating unstable and fluctuating values with an higher error in calculation).