Yan Tan

Combined value of susceptibility-weighted and perfusion-weighted imaging in assessing WHO grade for brain astrocytomas

To assess the value of combining susceptibility‐weighted imaging (SWI) and dynamic susceptibility‐weighted contrast‐enhanced (DSC) perfusion‐weighted MRI (PWI) in assessing World Health Organization (WHO) grade for brain astrocytoma.

Differentiation of high-grade-astrocytomas from solitary-brain-metastases: Comparing diffusion kurtosis imaging and diffusion tensor imaging

OBJECTIVE To compare the value of MRI diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) in differentiating high-grade-astrocytomas from solitary-brain-metastases. METHODS Thirty-one high-grade-astrocytomas and twenty solitary-brain-metastases were retrospectively identified. DKI parameters [mean kurtosis (MK), radial kurtosis (Kr), and axial kurtosis (Ka)] and DTI parameters [fractional anisotropy (FA) and mean diffusivity (MD)] values with and without correction by contralateral normal-appearing white matter (NAWM) in the tumoral solid part and peritumoral edema, were compared using the t-test. Receiver operating characteristic (ROC) curves were used to test for the best parameters. RESULTS The DKI values (MK, Kr, and Ka) and DTI values (FA and MD) in tumoral solid parts did not show significant differences between the two groups. Corrected and uncorrected MK, Kr, and Ka values in peritumoral edema were significantly higher in high-grade-astrocytomas than solitary-brain-metastases, and MD values without correction were lower in high-grade astrocytomas than solitary-brain-metastases. The areas under curve (AUC) of corrected Ka (1.000), MK (0.889), and Kr (0.880) values were significantly higher than those of MD (0.793) and FA (0.472) values. The optimal thresholds for corrected MK, Kr, Ka, and MD were 0.369, 0.405, 0.483, and 2.067, respectively. CONCLUSION DKI and directional analysis could lead to improved differentiation with better sensitivity and directional specificity than DTI.

Comparison of the values of MRI diffusion kurtosis imaging and diffusion tensor imaging in cerebral astrocytoma grading and their association with aquaporin-4

OBJECTIVE To compare the value of MRI diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) in grading cerebral astrocytomas and to analyze the correlation of respective parameters with aquaporin-4 (AQP4) expression. METHODS Sixty patients with cerebral astrocytoma, including low-grade astrocytomas (LGA, n = 25) and high-grade astrocytomas (HGA, n = 35), were studied. The values of DKI parameters (mean kurtosis [MK], radial kurtosis [Kr], and axial kurtosis [Ka]) and DTI parameters (fractional anisotropy, mean diffusivity [MD]) corrected by contralateral normal-appearing white matter in the solid parts of the tumors and peritumoral edema were compared. Receiver operating characteristic curves were used to identify the best parameters. Spearman correlation analysis was conducted to assess the correlation of AQP4 expression with each parameter value. RESULTS MK, Ka, and Krvalues were significantly higher whereas MD values were significantly lower in the solid parts of HGA, as compared to those of LGA. MK value in peritumoral edematous tissue was significantly higher in HGA as compared to that in LGA. Ka (0.889) had the largest area under the curve (AUC), followed by MK (0.840), Kr (0.750), and MD (0.764). The AUC of Kaand MK was significantly higher than that of MD. Optimal thresholds for MK, Ka, Kr, and MD for differentiating the two groups were 0.490, 0.525, 0.432, and 1.493, respectively. The AQP4 expression in the solid parts of the tumors was significantly higher in HGAs. MK, Kr, Kavalues positively correlated with the AQP4 expression, whereas MD showed a slight negative correlation with AQP4. CONCLUSION Use of DKI improved grading of cerebral astrocytomas when compared with DTI. DKI parameters appeared to reflect the level of AQP4 expression in astrocytomas.

Susceptibility-weighted imaging: the value in cerebral astrocytomas grading.

OBJECTIVE To investigate the value of susceptibility weighted imaging (SWI) in evaluating the histopathologic grade of cerebral astrocytomas and compare the relative value of SWI and conventional magnetic resonance imaging (MRI) sequences. MATERIALS AND METHODS This is an analysis of 26 untreated patients with pathologically confirmed astrocytomas. The tumors were classified as low grade (grade I-II: 12 cases) or high grade (grade III-IV: 14 cases). Imaging was performed with a 3.0 T MRI scanner. Conventional sequences [T1-weighted imaging (T1WI), contrast enhanced T1WI (CE-T1WI), T2-weighted imaging (T2WI), and T2 FLuid Attenuated Inversion Recovery (T2FLAIR)] and SWI sequence (including CE-SWI) were done. The number of small vessels and the amount of blood products in the tumors were determined for each sequence. Differences between the two groups were analyzed statistically. RESULTS SWI was more sensitive than conventional sequences (T1WI, CE-T1WI, T2WI, and T2FLAIR) in visualizing small vessels and microhemorrhages in cerebral astrocytomas (P < 0.01). CE-SWI was better than CE-T1WI sequences for visualizing tumor small vessels and microhemorrhages. SWI visualized greater numbers of small vessels and areas of microhemorrhages in high-grade tumors than in low-grade tumors (P < 0.01). This was especially true after contrast administration (P < 0.01). CONCLUSION SWI plays an important role in astrocytoma grading, especially for enhanced astrocytomas after contrast injection. CE-SWI was better than CE-T1WI in visualizing tumor architecture.

Clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres.

Clear cell myomelanocytic tumors (CCMTs) of the falciform ligament/ligamentum teres are extremely rare. CCMTs are a variant of perivascular epithelioid cell tumors. We present a case of hepatic CCMT in a 54-year-old woman with abdominal pain. The patient had an 8.8 cm well-demarcated tumor in the right lobe of the liver. Contrast-enhanced computed tomography showed a heterogeneous mass that enhanced significantly in the arterial and portal venous phases, and was less enhanced in the delayed phase. The patient underwent a right hemihepatectomy and cholecystectomy. The tumor cells had clear to slightly eosinophilic cytoplasm, vesicular nuclei, and were positive for HMB-45 and smooth muscle actin. The patient had no recurrence after 36 months follow-up. A review of the literature identified 10 hepatic CCMTs. Hepatic CCMTs are usually benign tumors of young women that present as large masses located in the right lobe of the liver.

Grading of Gliomas by Using Radiomic Features on Multiple Magnetic Resonance Imaging (MRI) Sequences

Background Gliomas are the most common primary brain neoplasms. Misdiagnosis occurs in glioma grading due to an overlap in conventional MRI manifestations. The aim of the present study was to evaluate the power of radiomic features based on multiple MRI sequences – T2-Weighted-Imaging-FLAIR (FLAIR), T1-Weighted-Imaging-Contrast-Enhanced (T1-CE), and Apparent Diffusion Coefficient (ADC) map – in glioma grading, and to improve the power of glioma grading by combining features. Material/Methods Sixty-six patients with histopathologically proven gliomas underwent T2-FLAIR and T1WI-CE sequence scanning with some patients (n=63) also undergoing DWI scanning. A total of 114 radiomic features were derived with radiomic methods by using in-house software. All radiomic features were compared between high-grade gliomas (HGGs) and low-grade gliomas (LGGs). Features with significant statistical differences were selected for receiver operating characteristic (ROC) curve analysis. The relationships between significantly different radiomic features and glial fibrillary acidic protein (GFAP) expression were evaluated. Results A total of 8 radiomic features from 3 MRI sequences displayed significant differences between LGGs and HGGs. FLAIR GLCM Cluster Shade, T1-CE GLCM Entropy, and ADC GLCM Homogeneity were the best features to use in differentiating LGGs and HGGs in each MRI sequence. The combined feature was best able to differentiate LGGs and HGGs, which improved the accuracy of glioma grading compared to the above features in each MRI sequence. A significant correlation was found between GFAP and T1-CE GLCM Entropy, as well as between GFAP and ADC GLCM Homogeneity. Conclusions The combined radiomic feature had the highest efficacy in distinguishing LGGs from HGGs.

Brainstem Congestion Due to Dural Arteriovenous Fistula at the Craniocervical Junction: Case Report and Review of the Literature

BACKGROUND Dural arteriovenous fistulas (DAVFs) at the craniocervical junction are rare. Clinical manifestations range from acute or chronic myelopathy to subarachnoid hemorrhage to brainstem dysfunction. We encountered 4 cases of DAVFs at the craniocervical junction with progressive brainstem dysfunction and investigated the typical magnetic resonance imaging (MRI) features using T2-weighting imaging, susceptibility-weighted imaging, diffusion-weighted imaging, and contrast-enhanced imaging. Literature review revealed 10 case reports of DAVFs at the craniocervical junction manifesting with brainstem dysfunction. CASE DESCRIPTION Four patients presented with DAVFs at the craniocervical junction with progressive brainstem dysfunction. Two patients underwent midline suboccipital craniotomy and C1 laminectomy, and 1 patient underwent transarterial endovascular embolization with Onyx 18 under general anesthesia. All neurologic deficits gradually improved after the operation. In the fourth case, the patient received conservative treatment and did not undergo any surgical procedure. MRI showed high signal intensity on T2-weighted imaging, magnetic resonance angiography, and magnetic resonance venography. Abnormal dilated vessels and flow-void signs around the lesions were detected on susceptibility-weighted imaging and contrast-enhanced images. Two cases revealed no abnormalities and had improved neurological deficits than those showed on diffusion-weighted imaging. CONCLUSIONS Susceptibility-weighted imaging, diffusion-weighted imaging, or contrast-enhanced scanning should be used during MRI examination of patients with progressive brainstem dysfunction to differentiate DAVFs at the craniocervical junction from other diseases, such as glioma or infection. Prompt diagnosis using MRI is of great significance in producing good functional outcomes of the patients.

A multi-sequence and habitat-based MRI radiomics signature for preoperative prediction of MGMT promoter methylation in astrocytomas with prognostic implication

ObjectivesOxygen 6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is a significant prognostic biomarker in astrocytomas, especially for temozolomide (TMZ) chemotherapy. This study aimed to preoperatively predict MGMT methylation status based on magnetic resonance imaging (MRI) radiomics and validate its value for evaluation of TMZ chemotherapy effect.MethodsWe retrospectively reviewed a cohort of 105 patients with grade II-IV astrocytomas. Radiomic features were extracted from the tumour and peritumoral oedema habitats on contrast-enhanced T1-weighted images, T2-weighted fluid-attenuated inversion recovery images and apparent diffusion coefficient (ADC) maps. The following radiomics analysis was structured in three phases: feature reduction, signature construction and discrimination statistics. A fusion radiomics signature was finally developed using logistic regression modelling. Predictive performance was compared between the radiomics signature, previously reported clinical factors and ADC parameters. Validation was additionally performed on a time-independent cohort (n = 31). The prognostic value of the signature on overall survival for TMZ chemotherapy was explored using Kaplan Meier estimation.ResultsThe fusion radiomics signature exhibited supreme power for predicting MGMT promoter methylation, with area under the curve values of 0.925 in the training cohort and 0.902 in the validation cohort. Performance of the radiomics signature surpassed that of clinical factors and ADC parameters. Moreover, the radiomics approach successfully divided patients into high-risk and low-risk groups for overall survival after TMZ chemotherapy (p = 0.03).ConclusionsThe proposed radiomics signature accurately predicted MGMT promoter methylation in patients with astrocytomas, and achieved survival stratification for TMZ chemotherapy, thus providing a preoperative basis for individualised treatment planning.Key Points• Radiomics using magnetic resonance imaging can preoperatively perform satisfactory prediction of MGMT methylation in grade II-IV astrocytomas.• Habitat-based radiomics can improve efficacy in predicting MGMT methylation status.• Multi-sequence radiomics signature has the power to evaluate TMZ chemotherapy effect.