Comparative study of pulsed-continuous arterial spin labeling and dynamic susceptibility contrast imaging by histogram analysis in evaluation of glial tumors

Comparison of ASL and DSC perfusion methods in the evaluation of response to treatment in patients with a history of treatment for malignant brain tumor

OBJECTIVE

Perfusion MRI is of great benefit in the post-treatment evaluation of brain tumors. Interestingly, dynamic susceptibility contrast-enhanced (DSC) perfusion has taken its place in routine examination for this purpose. The use of arterial spin labeling (ASL), a perfusion technique that does not require exogenous contrast material injection, has gained popularity in recent years. The aim of the study was to compare two different perfusion techniques, ASL and DSC, using qualitative and quantitative measurements and to investigate the diagnostic effectiveness of both. The fact that the number of patients is higher than in studies conducted with 3D pseudo-continious ASL (pCASL), the study group is heterogeneous as it consists of patients with both metastases and glial tumors, the use of 3D Turbo Gradient Spin Echo (TGSE), and the inclusion of visual (qualitative) assessment make our study unique.

METHODS

Ninety patients, who were treated for malignant brain tumor, were enrolled in the retrospective study. DSC Cerebral Blood Volume (CBV), Cerebral Blood Flow (CBF) and ASL CBF maps of each case were obtained. In qualitative analysis, the lesions of the cases were visually classified as treatment-related changes (TRC) and relapse/residual mass (RRT). In the quantitative analysis, three regions of interest (ROI) measurements were taken from each case. The average of these measurements was compared with the ROI taken from the contralateral white matter and normalized values (n) were obtained. These normalized values were compared across events.

RESULTS

Uncorrected DSC normalized CBV (nCBV), DSC normalized CBF (nCBF) and ASL nCBF values of RRT cases were higher than those of TRC cases (p < 0.001). DSC nCBV values were correlated with DSC nCBF (r: 0.94, p < 0.001) and correlated with ASL nCBF (r: 0.75, p < 0.001). Similarly, ASL nCBF was positively correlated with DSC nCBF (r: 0.79 p < 0.01). When the ROC curve parameters were evaluated, the cut-off values were determined as 1.211 for DSC nCBV (AUC: 0.95, 93% sensitivity, 82% specificity), 0.896 for DSC nCBF (AUC; 0.95, 93% sensitivity, 82% specificity), and 0.829 for ASL nCBF (AUC: 0.84, 78% sensitivity, 75% specificity). For qualitative evaluation (visual evaluation), inter-observer agreement was found to be good for ASL CBF (0.714), good for DSC CBF (0.790), and excellent for DSC CBV (0.822). Intra-observer agreement was also evaluated. For the first observer, good agreement was found in ASL CBF (0.626, 70% sensitive, 93% specific), in DSC CBF (0.713, 76% sensitive, 95% specific), and in DSC CBV (0.755, 87% sensitive - 88% specific). In the second observer, moderate agreement was found in ASL CBF (0.584, 61% sensitive, 97% specific) and DSC CBF (0.649, 65% sensitive, 100% specific), and excellent agreement in DSC CBV (0.800, 89% sensitive, 90% specific).

CONCLUSION

It was observed that uncorrected DSC nCBV, DSC nCBF and ASL nCBF values were well correlated with each other. In qualitative evaluation, inter-observer and intra-observer agreement was higher in DSC CBV than DSC CBF and ASL CBF. In addition, DSC CBV is found more sensitive, ASL CBF and DSC CBF are found more specific for both observers. From a diagnostic perspective, all three parameters DSC CBV, DSC CBF and ASL CBF can be used, but it was observed that the highest rate belonged to DSC CBV.

3D pCASL-perfusion in preoperative assessment of brain gliomas in large cohort of patients

The aim of the study was to evaluate the role of pseudocontinuous arterial spin labeling perfusion (pCASL-perfusion) in preoperative assessment of cerebral glioma grades. The study group consisted of 253 patients, aged 7-78 years with supratentorial gliomas (65 low-grade gliomas (LGG), 188 high-grade gliomas (HGG)). We used 3D pCASL-perfusion for each patient in order to calculate the tumor blood flow (TBF). We obtained maximal tumor blood flow (maxTBF) in small regions of interest (30 ± 10 mm²) and then normalized absolute maximum tumor blood flow (nTBF) to that of the contralateral normal-appearing white matter of the centrum semiovale. MaxTBF and nTBF values significantly differed between HGG and LGG groups (p < 0.001), as well as between patient groups separated by the grades (grade II vs. grade III) (p < 0.001). Moreover, we performed ROC-analysis which demonstrated high sensitivity and specificity in differentiating between HGG and LGG. We found significant differences for maxTBF and nTBF between grade III and IV gliomas, however, ROC-analysis showed low sensitivity and specificity. We did not observe a significant difference in TBF for astrocytomas and oligodendrogliomas. Our study demonstrates that 3D pCASL-perfusion as an effective diagnostic tool for preoperative differentiation of glioma grades.

[Consistency analysis between 3D arterial spin labeling and dynamic susceptibility contrast perfusion magnetic resonance imaging in perfusion imaging of brain tumor]

OBJECTIVE

To analyze the consistency between cerebral blood flow (CBF) of 3D arterial spin labeling (3D ASL) and dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-PWI) in the measurement of brain tumors.

METHODS

Nineteen patients with pathologically confirmed brain tumors were enrolled in this study.The brain tumors included glioma (n=9), meningioma (n=5), hemangioblastoma (n=2), cerebral metastasis (n=2) and cavernous hemangioma (n=1).Both ASL and DSC MRI were performed in all the 19 patients (57 regions of interest), and CBF was quantitatively determined.

RESULTS

A significant consistency was found between CBF measured by 3D ASL and the relative CBF (rCBF) determined by DSC (P=0.005).

CONCLUSION

3D ASL and DSC PWI are consistent in evaluating blood flow in brain tumors and can accurately evaluate brain tumors perfusion.

Using arterial spin labeling blood flow and its histogram analysis to distinguish early-stage nasopharyngeal carcinoma from lymphoid hyperplasia

To investigate the feasibility of arterial spin labeling (ASL) blood flow (BF) and its histogram analysis to distinguish early-stage nasopharyngeal carcinoma (NPC) from nasopharyngeal lymphoid hyperplasia (NPLH).Sixty-three stage T1 NPC patients and benign NPLH patients underwent ASL on a 3.0-T magnetic resonance imaging system. BF histogram parameters were derived automatically, including the mean, median, maximum, minimum, kurtosis, skewness, and variance. Absolute values were obtained for skewness and kurtosis (absolute value of skewness [AVS] and absolute value of kurtosis [AVK], respectively). The Mann-Whitney U test, receiver operating characteristic curve, and multiple logistic regression models were used for statistical analysis.The mean, maximum, and variance of ASL BF values were significantly higher in early-stage NPC than in NPLH (all P < 0.0001), while the median and AVK values of early-stage NPC were also significantly higher than those of NPLH (all P < 0.001). No significant difference was found between the minimum and AVS values in early-stage NPC compared with NPLH (P = 0.125 and P = 0.084, respectively). The area under the curve (AUC) of the maximum was significantly higher than those of the mean and median (P < 0.05). The AUC of variance was significantly higher than those of the other parameters (all P < 0.05). Multivariate analysis showed that variance was the only independent predictor of outcome (P < 0.05).ASL BF and its histogram analysis could distinguish early-stage NPC from NPLH, and the variance value was a unique independent predictor.

The diagnostic value of quantitative analysis of ASL, DSC-MRI and DKI in the grading of cerebral gliomas: a meta-analysis

OBJECTIVE

To perform quantitative analysis on the efficacy of using relative cerebral blood flow (rCBF) in arterial spin labeling (ASL), relative cerebral blood volume (rCBV) in dynamic magnetic sensitivity contrast-enhanced magnetic resonance imaging (DSC-MRI), and mean kurtosis (MK) in diffusion kurtosis imaging (DKI) to grade cerebral gliomas.

METHODS

Literature regarding ASL, DSC-MRI, or DKI in cerebral gliomas grading in both English and Chinese were searched from PubMed, Embase, Web of Science, CBM, China National Knowledge Infrastructure (CNKI), and Wanfang Database as of 2019. A meta-analysis was performed to evaluate the efficacy of ASL, DSC-MRI, and DKI in the grading of cerebral gliomas.

RESULT

A total of 54 articles (11 in Chinese and 43 in English) were included. Three quantitative parameters in the grading of cerebral gliomas, rCBF in ASL, rCBV in DSC-MRI, and MK in DKI had the pooled sensitivity of 0.88 [95% CI (0.83,0.92)], 0.92 [95% CI (0.83,0.96)], 0.88 [95% CI (0.82,0.92)], and the pooled specificity of 0.91 [95% CI (0.84,0.94)], 0.81 [95% CI (0.73,0.88)], 0.86 [95% CI (0.78,0.91)] respectively. The pooled area under the curve (AUC) were 0.95 [95% CI (0.93,0.97)], 0.91 [95% CI (0.89,0.94)], 0.93 [95% CI (0.91,0.95)] respectively.

CONCLUSION

Quantitative parameters rCBF, rCBV and MK have high diagnostic accuracy for preoperative grading of cerebral gliomas.

A simple model for glioma grading based on texture analysis applied to conventional brain MRI

Accuracy of glioma grading is fundamental for the diagnosis, treatment planning and prognosis of patients. The purpose of this work was to develop a low-cost and easy-to-implement classification model which distinguishes low-grade gliomas (LGGs) from high-grade gliomas (HGGs), through texture analysis applied to conventional brain MRI. Different combinations of MRI contrasts (T1Gd and T2) and one segmented glioma region (necrotic and non-enhancing tumor core, NCR/NET) were studied. Texture features obtained from the gray level size zone matrix (GLSZM) were calculated. An under-sampling method was proposed to divide the data into different training subsets and subsequently extract complementary information for the creation of distinct classification models. The sensitivity, specificity and accuracy of the models were calculated, and the best model explicitly reported. The best model included only three texture features and reached a sensitivity, specificity and accuracy of 94.12%, 88.24% and 91.18%, respectively. According to the features of the model, when the NCR/NET region was studied, HGGs had a more heterogeneous texture than LGGs in the T1Gd images, and LGGs had a more heterogeneous texture than HGGs in the T2 images. These novel results partially contrast with results from the literature. The best model proved to be useful for the classification of gliomas. Complementary results showed that the heterogeneity of gliomas depended on the MRI contrast studied. The chosen model stands out as a simple, low-cost, easy-to-implement, reproducible and highly accurate glioma classifier. Importantly, it should be accessible to populations with reduced economic and scientific resources.

Diagnostic utility of arterial spin labeling in identifying changes in brain perfusion in patients with carbon monoxide poisoning

OBJECTIVE

Carbon monoxide (CO) poisoning is one of the most common poisonings worldwide. The affinity of hemoglobin for CO is significantly higher than that for oxygen, and the formation of carboxy-hemoglobin leads to a decrease in the capacity of blood to transport oxygen to tissues, tissue hypoxia, and early perfusion changes in the affected tissue. This study aimed to investigate the utility of arterial spin labeling perfusion imaging (ASL-PI) in revealing cerebral vascular hemodynamic changes in patients presenting to the emergency room with CO poisoning and to compare findings with those from diffusion-weighted imaging (DWI).

METHOD

This study was conducted between November 2016 and May 2019 and was approved by the local ethics committee. DWI and ASL-PI examinations were performed in 83 patients who presented to the emergency room with CO poisoning. Four regions-the cerebral cortex, basal ganglia, cerebral white matter, and cerebellum-were evaluated for alterations in perfusion and diffusion, and findings from DWI and ASL-PI were compared.

RESULTS

The study group included 39 (50.6%) females and 38 (49.4%) males, with a mean (±SD) age of 40.08 ± 20.41 years (range, 7-86 years). DWI revealed restricted diffusion in 10 regions in 6 (7.8%) patients, including the basal ganglia (n = 2), cerebral white matter (n = 2), cerebral cortex (n = 3), and the cerebellum (n = 3). ASL-PI revealed hypo-perfusion in 64 regions in 36 (46.8%) patients, including the basal ganglia (n = 21), cerebral white matter (n = 12), cerebral cortex (n = 23), and cerebellum (n = 7).

CONCLUSION

ASL-PI provided additional information when used to identify perfusion changes in the brains of individuals who experienced CO poisoning and was superior to DWI as it revealed early changes in the brain. Considering its limitations, ASL-PI can be routinely used with DWI in cases of CO poisoning.

Expression and clinical significance of p73 in Wilms tumor in children

Expression and clinical significance of p73 in children with Wilms tumor (WT) were investigated. A retrospective analysis was carried out on 50 children diagnosed with WT in the People's Hospital of Rizhao, from July 2013 to January 2015 (study group), and 20 healthy children with similar age and sex who received health examinations in the same hospital during the same period (control group). The relative expression of p73 mRNA in the peripheral blood of each group was detected by reverse transcription-quantitative PCR (RT-qPCR) in order to study the association between p73 and the clinicopathological parameters of WT, as well as the impact of p73 on the patient prognosis. The two groups were not statistically different in respect to the clinical data of patients (P>0.05); the expression level of p73 in the blood samples of the study group was significantly higher than that of the control group (t=11.44, P<0.01); the expression of p73 in the study group was associated with factors, including tumor size, pathological type and lymphatic metastasis. Considering the mean value of the expression of p73 (3.32) as the boundary, the patients with expression value of p73 <3.32 were studied as the low-expression group, and patients with expression value of p73 >3.32 comprised the high-expression group. At the end of the follow-up, the median survival time and the survival rate of the patients in the high-expression group were significantly lower than those of the low-expression group (P<0.05). The high expression of p73 in the peripheral blood of children with WT was positively correlated with the clinical stage of the tumor, and was closely related with the low survival rate of patients.