Reliability of diffusion-weighted imaging and perfusion parameters in the differential diagnosis of malignant and considered benign intracranial tumors: a single-center study
Authors: Talybov R. S. , Trofimova T. N. , Tamrazov R. I. , Shvetsov I. V. , Mochalov V. V. , Spasennikov V. V. , Duboshinsky R. I. 
Published: July 2023

INTRODUCTION: Intracranial meningiomas are the most common considered benign tumors of the central nervous system with clinically aggressive behavior. Meningiomas account for up to 36% of all brain tumors. Metastases, are highly malignant brain lesions with an undetermined incidence of World Health Organization. It is believed that up to 30% of adult patients with cancer of one localization or another suffer from secondary tumors of the brain. The vast majority of meningiomas originate from the coverings of the brain, and more than 90% are solitary. Intracranial meningeal metastases occur in 8–9%, and in 10% the brain is the only secondary tumor site, and in 50% of cases metastases are solitary. Usually, the task of distinguishing between meningioma and a dural metastasis does not cause difficulties. In some cases differential diagnosis between these tumors is ambiguous, since meningiomas and dural solitary metastases (dMTS) may have similar characteristics: a cavityless solid appearance, restricted diffusion of water molecules, presence of extensive peritumoral edema, and an identical contrast enhancement pattern.

OBJECTIVE: To determine the significance of multiparametric mapping (MR-perfusion and apparent diffusion coefficient) for the differential diagnosis of meningioma and solitary dural metastasis.

MATERIALS AND METHODS: This study included 100 patients with newly diagnosed CNS tumors, who subsequently underwent examination at the Meditsinskii gorod (Tyumen, Russia) with histological verification in the period from 2017 to 2022. The mean age of the patients was 54 years, the median was 58 years. Depending on the histological data, 2 groups of patients were distinguished: 1–50 cases with meningiomas, 2–50 cases with solitary meningeal metastatic lesions. The examination was performed with a General Electric Signa Voyager 1.5Т MRI machine before and after contrast enhancement.

Statistics. Statistical analysis was performed using IBM SPSS (version 24.0). Gender, age, presence of dislocation of midline structures, bone invasion, and severity of perifocal edema were compared for both groups of patients using Pearson’s Chi-square test. ADC, CBV, rCBV, CBF, rCBF, MTT values were compared for both groups of patients using the Mann-Whitney U test. The optimal cut-off value for sensitivity and specificity was determined by analysis of ROC curves. For all tests, the alpha level was set to p*≤0.05, p**≤0.01, p***≤0.001.

RESULTS: In the meningioma group, the mean ADC was 912.14×10−6 mm2/s (SD: ±102.7×10−6 mm2/s). Median CBV was 19.25 ml/100g (CI: 18.08–28.96 ml/100g), median increase in rCBV was 4.1-fold (SD: 4.09–5.46). Median CBF was 155 ml/100g/min (SD: 157.48–206.65 ml/100g/min), median increase in rCBF was 3.85-fold (SD: 3.98–5.28). Median MTT was 11 seconds (SD: 10.18–11.29 seconds). In the metastasis group, the mean ADC was 867.67×10−6 mm2/s (SD: ±138.6×10−6 mm2/s). Median CBV was 39.85 ml/100g SDI: 36.50–46.83 ml/100g), median increase in rCBV was 7.15-fold (SD: 6.64–7.80). Median CBF was 293 ml/100g/min SDI: 261.65–306.12 ml/100g/min), median increase in rCBF was 6.7-fold (SD: 5.97–6.93). Median MTT is 10.85 seconds (SD: 10.15–10.86 seconds).

The cut-off value for CBV was 28.25 ml/100g. The sensitivity and specificity of the method are 76.5% and 78%, respectively. The cut-off value for rCBV was 5.4. The sensitivity and specificity of the method are 74.5% and 82%, respectively.

The threshold value of the CBF was 217.9 ml/100g/min. The sensitivity and specificity of the method are 80.4% and 86%, respectively.

The cut-off value for rCBF was 5.6. The sensitivity and specificity of the method are 82.4% and 76%, respectively.

DISCUSSION: Based on the results of the study, it was found that the use of mpMRI in the differential diagnosis of meningiomas and dural SMTS is limited by the similarity of the apparent diffusion coefficient values. The assumption, previously put forward in the literature, about the presence of a statistically significant difference in ADC values that allow to differentiate these tumors, was not confirmed. When analyzing perfusion data, dural SMTS showed higher CBF values compared to meningiomas (p<0.001). A threshold value of the CBF was determined, which amounted to 217.9 ml/100 g/min, above which it is possible to predict dural SMTS with a sensitivity and specificity of 80 and 86%.

CONCLUSION: Diffusion-weighted images are not reliable criteria for differentiating meningiomas from dural SMTS and should not influence the diagnosis suggested by imaging. The meningeal lesion perfusion technique predicts metastasis with a sensitivity and specificity close to 80–90% and deserves attention in making a diagnosis. Since dural MTS differ from meningiomas in the severity of neoangiogenesis and, accordingly, in greater vascular permeability, the technique for assessing vascular permeability (the wash-in parameter with dynamic contrast enhancement) can potentially be a clarifying criterion for distinguishing between dural lesions.