Perfusion-weighted MR Imaging Research Articles

Magnetic Resonance Perfusion-Weighted Imaging in Predicting Hemorrhagic Transformation of Acute Ischemic Stroke: A Retrospective Study.

Hemorrhagic transformation (HT) is one of the common complications in patients with acute ischemic stroke (AIS). This study aims to investigate the value of different thresholds of Tmax generated from perfusion-weighted MR imaging (PWI) and the apparent diffusion coefficient (ADC) value in the prediction of HT in AIS. A total of 156 AIS patients were enrolled in this study, with 55 patients in the HT group and 101 patients in non-HT group. The clinical baseline data and multi-parametric MRI findings were compared between HT and non-HT groups to identify indicators related to HT. The optimal parameters for predicting HT and the corresponding cutoff values were obtained using the receiver operating characteristic curve analysis of the volumes of ADC < 620 × 10-6 mm2/s and Tmax > 6 s, 8 s, and 10 s. The results showed that the volumes of ADC < 620 × 10-6 mm2/s and Tmax > 6 s, 8 s, and 10 s in the HT group were all significantly larger than that in the non-HT group and were all independent risk factors for HT. Early measurement of the volume of Tmax > 10 s had the highest value, with a cutoff lesion volume of 10.5 mL.

NI-3 FEASIBILITY OF MRI PERFUSION IN DISCRIMINATING BETWEEN EDEMA AND INFILTRATIVE AREAS IN THE PERI-GBM NON-CONTRAST T2 WEIGHTED HIGH AREA

Abstract Background Glioblastomas are highly infiltrative tumors, and differentiating between infiltrating tumors and vasogenic edema occurring in the non-enhancing T2-weighted hyperintense area is challenging. Here, we differentiated between infiltrating tumors and edemas in glioblastomas using dynamic perfusion-weighted MR imaging. Methods Data were collected from 33 patients with glioblastomas and 15 with meningioma as controls, who underwent resection at our institution between January 2019 and March 2022. The MRI data included T2 weighted images and contrast-enhanced T1 weighted images, and dynamic perfusion-weighted MR imaging. Two neurosurgeons manually assigned regions of interest (ROIs) to infiltrating tumors and vasogenic edema based on a previous report using conventional MRI features. The ratio of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) in the ROIs to that contralateral normal regions were calculated. We also histological analysis using histological specimens obtained by stereotactic biopsy in each ROI. Results CBF and MTT ratios of infiltrating tumors and edemas differed significantly (p&amp;lt;0.01), while CBF and MTT ratios of edemas and controls showed similarities. MTT values of controls and infiltrating tumors differed significantly (p=0.02). Receiver operating characteristic curve analysis revealed that CBF (area under the curve [AUC]=0.81) and MTT(AUC=0.95) were effective in distinguishing between infiltrating tumors and edemas. Pathological analysis revealed that cell density, MIB1-index, and microvessel density were higher in infiltrating tumors than in edemas. Conclusions Using dynamic perfusion-weighted MR imaging may prove useful in differentiating infiltrating tumors from edemas in the non-contrast T2 hyperintensity region of glioblastomas.

MR‐based follow‐up after brachytherapy and proton beam therapy in uveal melanoma

AbstractPurpose: Comparison of Magnetic Resonance Imaging (MRI) with conventional ultrasound for the follow‐up in Uveal Melanoma (UM) patients treated with brachytherapy or proton beam therapy (PBT).Methods: 26 UM patients were scanned before, 3, 6 and 12 months after ruthenium brachytherapy (n = 13) or PBT (n = 13) at 3Tesla MRI. Tumour prominence measurements were compared between MRI and ultrasound. On Perfusion weighted MR‐imaging (PWI), the relative enhancement and outflow at 2 min after peak were assessed. Treatment response was defined as a reduction of ≥0.6 mm prominence and/or ≥5% perfusion outflow was achieved.Results: Pretreatment prominences were comparable on MR and ultrasound (mean absolute difference 0.49 ± 0.46 mm), larger differences were observed at 3 and 6 months post treatment (0.88 ± 0.86 mm and 0.74 ± 0.72 mm, respectively). At 12 months post treatment, the difference was reduced to 0.55 ± 0.33 mm. Pretreatment, 76% of the UM showed a washout perfusion curve. The pretreatment average enhancement and outflow were 98% (SD:49%) and 31% (SD: 25%) respectively. At 3 months post treatment tumours showed 41% less outflow on average with more favourable perfusion curves (e.g. 68% showed a persistent or plateau curve). At 6 and 12 months post treatment, tumours continued to show less outflow (respectively, −47% and −38%) and more favourable perfusion curves (respectively, 79% and 76% with either persistent or plateau curves). These, generally favourable, perfusion changes were also observed when no reduction in prominence was yet apparent, which is why treatment response was more frequently detected on MRI as opposed to ultrasound. For example, at 3 months post treatment &gt;80% of patients were already detected on MRI versus 46% on ultrasound.Conclusions: MRI is beneficial for the follow‐up of UM patients, especially for PBT treated patients as these generally take longer before a reduction in prominence can be observed.

Parameters of MR perfusion-weighted imaging predict the response and prognosis to high-dose methotrexate-based chemotherapy in immunocompetent patients with primary central nervous system lymphoma

To investigate the effectiveness of dynamic susceptibility contrast-perfusion weighted imaging (DSCPWI) in predicting the progression-free survival (PFS) and chemotherapeutic responsiveness of primary central nervous system lymphoma (PCNSL) before high-dose methotrexate-based chemotherapy. DSCPWI was used to analyze 35 patients who had pathology-confirmed PCNSL. Relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), relative mean transit time (rMTT) and relative time to peak (rTTP) were measured on parameter maps. The 5th, 50th and 95th percentile values of every parameter were recorded for enhanced tumors and compared with the parameters of the normally contralateral hemisphere. The ratio of each PWI parameter (rrCBV, rrCBF, rrMTT, rrTTP) was obtained. The influence of parameters on responsiveness and PFS was investigated by univariate Kaplan–Meier analysis and logistic regression and Cox regression for multivariate analysis with a stepwise method. Differences in PWI parameters between the higher and lower vascular endothelial growth factor (VEGF) groups were assessed by the Mann–Whitney U test. Eighteen patients achieved a complete response (CRi) after four initial cycles of chemotherapy. Patients with lower age (p = 0.011), higher VEGF (p < 0.001), higher Karnofsky Performance Status (KPS) (p < 0.001), higher rrCBV95% (p < 0.001), higher rrCBV50% (p = 0.016), higher rrCBF95% (p < 0.001), higher rrCBF50% (p = 0.002) showed better PFS; there was difference on age(p = 0.044), KPS (p < 0.001), VEGF (p < 0.001), rrCBV95% (p = 0.018), rrCBF95% (p = 0.018), rrCBF50% (p = 0.007) between CRi and nonCRi. Multivariate analysis demonstrated that rrCBF95% (p = 0.037, 95% confidence interval: 1.065–7.206) was significantly associated with PFS. rCBV and rCBF may be used to assess the responsiveness and prognosis of PCNSL, and rCBF95% may be a better predictor.

Dynamic susceptibility MR perfusion imaging of the brain: not a question of contrast agent molarity

Dynamic susceptibility contrast (DSC) perfusion-weighted MR imaging (PWI) is increasingly used in clinical neuroimaging for a range of conditions. More highly concentrated GBCAs (e.g., gadobutrol) are often preferred for DSC imaging because it is thought that more Gd is present in the volume of interest during first pass for a given equivalent injection rate. However, faster injection of a less viscous GBCA (e.g., gadoteridol) might generate a more compact and narrower contrast bolus thus obviating any perceived benefit of higher Gd concentration. This preliminary study aimed to analyze and compare DSC examinations in the healthy brain hemisphere of patients with brain tumors using gadobutrol and gadoteridol administered at injection rates of 4 and 6mL/s. Thirty-nine brain tumor patients studied with DSC-PWI were evaluated. A simplified gamma-variate model function was applied to calculate the mean peak, area under the curve (AUC), and full-width at half-maximum (FHWM) of concentration-time curves derived from ΔR2* signals at four different regions-of-interest (ROIs). Qualitative assessment of the derived CBV maps was also performed independently by 2 neuroradiologists. No qualitative or quantitative differences between the two GBCAs were observed when administered at a flow rate of 4mL/s. At a flow rate of 6mL/s, gadoteridol showed lower FWHM values. Gadobutrol and gadoteridol are equivalent for clinical assessment of qualitative CBV maps and quantitative perfusion parameters (FHWM) at a flow rate of 4mL/s. At 6mL/s, gadoteridol produces a narrower bolus shape and potentially improves quantitative assessment of perfusion parameters.

Intracranial dolichoectasia in patients with symptomatic intracranial atherosclerotic disease: Results from the MYRIAD study.

It is unknown whether intracranial atherosclerotic disease (ICAD), in addition to causing stenosis, also associates with abnormal arterial enlargement, a condition known as intracranial dolichoectasia (IDE). Across symptomatic ICAD patients, we aim to determine IDE prevalence and IDE impact on cerebral hemodynamics and recurrent cerebral ischemia. We analyzed 98 participants (mean age 63.8 11.9 years, 56.1% men) of the prospective observational study MYRIAD. Participants were enrolled within 21 days of an ischemic stroke or transient ischemic attack caused by moderate-to-severe ICAD. Semi-automatic vessel segmentation was used to determine diameters, length, and tortuosity-index of proximal intracranial arteries. Either ectasia (increased diameter) or dolichosis (increased length or TI) defined IDE. We assessed IDE association with new infarcts during 12-month follow-up, and IDE correlation with cerebral hemodynamics determined by quantitative MR-angiography (QMRA), MR-perfusion weighted-imaging, and transcranial Doppler breath-holding index. IDE was present in 35.7% of patients and 10.2% of symptomatic arteries. Basilar stenosis was associated with higher IDE prevalence (27.8% vs. 8.8%, p = 0.04), whereas other symptomatic arteries showed no association with IDE. Symptomatic arteries with IDE had lower hypoperfusion prevalence on MR-PWI (11.1% vs. 28.4%, p = 0.03). Increased diameter (r = 0.33, p<0.01) and tortuosity-index (r = 0.29, p = 0.01) showed positive correlation with QMRA flow rate. IDE was not associated with new infarcts during follow-up. IDE was common among symptomatic ICAD patients. IDE was not associated with stroke recurrence. Instead, increased diameter and tortuosity correlated with improved blood flow across the stenotic artery, suggesting that IDE may originate as an adaptive mechanism in ICAD.

Detecting non-germinomatous germ cell tumor component by arterial spin labeling perfusion-weighted MR imaging in central nervous system germ cell tumor

PurposeDifferentiating between germinoma and non-germinomatous germ cell tumor (NGGCT) is important because sensitivity to chemotherapy and/or radiotherapy is quite different between these two subgroups. In this study, we evaluated whether the arterial spin labeling (ASL) based perfusion-weighted imaging (PWI) could provide additional information for the differential diagnosis between germinoma and NGGCT. MethodBetween 2011 and 2018, 20 patients with central nervous system (CNS) germ cell tumor (GCT) who underwent preoperative MR imaging including ASL-PWI were enrolled in this study. Relative tumor blood flow (rTBF) was evaluated on ASL-PWI by manually placing regions of interest at gadolinium enhanced part of the tumors and normal subcortical white matter. Presence of intratumoral T1 hyperintense foci and apparent diffusion coefficient (ADC) were also evaluated. The final diagnosis was made by the combination of tumor markers and the histological diagnosis. ResultsAmong 20 patients of CNS-GCT, 11 were diagnosed as germinoma and 9 were diagnosed as NGGCT. In the germinoma subgroup, the rTBF ranged from 0.90 to 1.71 (mean 1.21, median 1.09), while it ranged from 1.14 to 5.75 (mean 3.91, median 3.31) in NGGCT subgroup. The receiver operating characteristic (ROC) curve showed that calculating rTBF is useful for differentiating between germinoma and NGGCT (area under the curve (AUC) 0.929, P = 0.0012) compared to intratumoral T1 hyperintense foci (AUC 0.788, P = 0.0304) and ADC (AUC 0.919, P = 0.0016). ConclusionsHigh rTBF obtained by ASL-PWI implied the presence of NGGCT component. This information might help in deciding the chemotherapy/radiotherapy intensity.

68Ga-PSMA-11 PET-CT vs. 18F-FDG PET-CT and MR perfusion-weighted imaging in preoperative cerebral gliomas diagnostics and histological grade prediction

68Ga-PSMA-11 PET-CT vs. 18F-FDG PET-CT and MR perfusion-weighted imaging in preoperative cerebral gliomas diagnostics and histological grade prediction

The role of imaging for the management of newly diagnosed glioblastoma in adults: a systematic review and evidence-based clinical practice guideline update.

These recommendations apply to adults with a newly diagnosed lesion with a suspected or histopathologically proven glioblastoma (GBM). What are the optimal imaging techniques to be used in the management of a suspected glioblastoma (GBM), specifically: which imaging sequences are critical for most accurately identifying or diagnosing a GBM and distinguishing this tumor from other tumor types? Critical Imaging for the Identification and Diagnosis of Glioblastoma Level II: In patients with a suspected GBM, it is recommended that the minimum magnetic resonance imaging (MRI) exam should be an anatomic exam with both T2 weighted, FLAIR and pre- and post-gadolinium contrast enhanced T1 weighted imaging. The addition of diffusion and perfusion weighted MR imaging can assist in the assessment of suspected GBM for the purposes of distinguishing GBM from other tumor types. Computed tomography (CT) can provide additional information regarding calcification or hemorrhage and also can be useful for subjects who are unable to undergo MR imaging. At a minimum, these anatomic sequences can help identify a lesion as well as its location, and potential for surgical intervention. Improvement of diagnostic specificity with the addition of non-anatomic (physiologic imaging) to anatomic imaging Level II: One blinded prospective study and a significant number of case series support the addition of diffusion and perfusion weighted MR imaging in the assessment of suspected GBM, for the purposes of distinguishing GBM from other tumor types (e.g., primary CNS lymphoma or metastases). Level III: It is suggested that magnetic resonance spectroscopy (MRS) and nuclear medicine imaging (PET 18F-FDG and 11C-MET) be used to provide additional support for the diagnosis of GBM.

Multimodal MR Features of 8 Cases of Epithelioid Glioblastoma.

Purpose The MRI features of epithelioid glioblastoma (eGBM) were analyzed. The apparent diffusion coefficient (ADC), MR perfusion-weighted imaging (PWI), and magnetic resonance spectroscopy (MRS) findings were quantitatively analyzed.Methods The MRI images of 8 cases of eGBM were analyzed retrospectively. The location and edge, signal, peritumoral edema, adjacent meningeal invasion, and enhancement of the lesions were observed. The ADC value, relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and N-acetylaspartate/acetylcholine (NAA/Cho) value were analyzed.Results Among the 8 patients, the tumors were mainly located in the temporal lobe (n = 3), frontal lobe (n = 3), and parietal lobe (n = 2). The lesion boundary was clear in 6 cases and unclear in 2. The lesions were superficial in 5 cases and in the deep white matter in 3. Internal hemorrhage was observed in 4 cases. There was cystic necrosis in 7 cases, and only 1 case was solid without cystic necrosis. There was no edema around the lesion in 1 case, severe edema in 5, and moderate edema in 2. In 4 cases, the adjacent meninges were involved, and in 1 case, the ependyma was involved. Two patients developed leptomeningeal metastasis within 2 months after the operation. The average ADC value of the tumor parenchyma among all 8 patients was7.15 × 10−4 mm2/s,which was 17.6% lower than that of the contralateral side. The Cho/NAA metabolite ratio was 5.27 and 0.81 in the lesions of 2 patients. The rCBV was 3.51 ml/100 g and 3.32 ml/100 g of lesions in 2 patients; these values were 36% and 29% higher, respectively, than those of the contralateral side. The rCBF was 31.5 ml/100 g/min and 82.1 ml/100 g/min of lesions in two patients; these values were 49% and 203% higher, respectively, than those of the contralateral side.Conclusion eGBM characteristics include a superficial location, easy cyst degeneration, easy necrosis and hemorrhage, and clear boundaries. It easily invades adjacent meninges and shows cerebrospinal fluid dissemination and metastasis. Combining new MR techniques, such as ADC values, PWI, and MRS, could be helpful for improving diagnostic accuracy.

Value of Diffusion-Weighted and Perfusion-Weighted MR Imaging in Differentiation of Recurrent Tongue Carcinoma from Post-Treatment Changes

Abstract Background: Tongue carcinoma is characterized by high recurrence rate. Thus, post-treatment follow-up imaging is critically important. Advanced Magnetic Resonance Imaging (MRI) techniques can be employed for this purpose due to the limited accuracy of conventional MRI. Aim of Study: Evaluation of the value of Diffusion Weight-ed (DW) and perfusion weighted MRI implementation in the post-treatment follow-up of tongue carcinoma. Patients and Methods: This study was conducted on 23 patients on post-treatment follow-up of tongue carcinoma. They underwent DW-MRI and Dynamic Contrast Enhanced (DCE) perfusion T1-weighted MRI to differentiate between recurrent tumor and post-treatment changes. Apparent Diffu-sion Coefficient (ADC) was estimated, perfusion MR quali-tative and semiquantitative assessment was performed. Re-sulting data were compared to histopathologic characterization (n=18) and further clinical and radiological follow-up (n=5) which were considered as the reference standards. Results: The mean ADC value of recurrent tongue carci-noma (1.029±0.207 X 10–3mm2/s) was significantly lower (p < 0.001) than the mean ADC value of post-treatment changes (1.425±0.238 X 10–3mm2/s). The ADC threshold used for differentiating recurrent tumor from post-treatment changes was 1.175 X 10–3mm2/s with Area Under the Curve (AUC) of 0.938 and diagnostic accuracy of 82.6%. Among the DCE perfusion weighted MR parameters, the wash in rate and Area Under Gadolinium Curve (AUGC) displayed the highest diagnostic accuracy (73.9%) with thresholds of 18.65a.u/s and 126826.7m.M.s respectively. The combined use of both DW-MRI and perfusion weighted MRI showed the highest diagnostic accuracy. Conclusion: The DW MRI is a non-invasive technique providing accurate post-treatment follow-up assessment of tongue carcinoma. The perfusion weighted MRI provides lower diagnostic accuracy than DWI. The combined use of both techniques provides superior differentiation of tumor recurrence from post-treatment changes.

Assessment of Interhemispheric Cerebral Perfusion Deficit in Carotid Artery Stenosis.

Asymptomatic carotid stenosis patients manifest compromised cognitive performance compared to controls. Cerebral perfusion deficit could be an important contributor to cognitive impairment. The relationship between carotid stenosis and cerebral perfusion deficit is not established. If established, this could lead to a more informed selection of ACS patients likely to benefit from carotid revascularization. Perfusion-weighted MR imaging (PWI) is a clinically viable non-invasive technique to quantify cerebral perfusion. However, its impact is limited due to lack of efficient clinical tools to analyze PWI data in different brain regions for characterizing interhemispheric perfusion asymmetry. Development of automated approaches to characterize clinically relevant perfusion deficits is therefore required. Moreover, there is no established evidence of association between perfusion deficit and stenosis severity. In this paper, we propose an approach to quantify interhemispheric perfusion differences in different brain regions using clinical data. Our proposed metrics, based on the PWI mean transit time, for characterizing difference between ipsilateral and contralateral hemispheres demonstrate a very strong relationship with Doppler ultrasound based peak systolic velocity measured at stenosis. Our approach also highlights dependence of perfusion asymmetry on effective collateralization through the cerebral vasculature. In future studies, we plan to extend this method to a larger cohort and refine the methods for validating novel biomarker for risk-stratification of carotid stenosis.

Radiomics prognostication model in glioblastoma using diffusion- and perfusion-weighted MRI

We aimed to develop and validate a multiparametric MR radiomics model using conventional, diffusion-, and perfusion-weighted MR imaging for better prognostication in patients with newly diagnosed glioblastoma. A total of 216 patients with newly diagnosed glioblastoma were enrolled from two tertiary medical centers and divided into training (n = 158) and external validation sets (n = 58). Radiomic features were extracted from contrast-enhanced T1-weighted imaging, fluid-attenuated inversion recovery, diffusion-weighted imaging, and dynamic susceptibility contrast imaging. After radiomic feature selection using LASSO regression, an individualized radiomic score was calculated. A multiparametric MR prognostic model was built using the radiomic score and clinical predictors. The results showed that the multiparametric MR prognostic model (radiomics score + clinical predictors) exhibited good discrimination (C-index, 0.74) and performed better than a conventional MR radiomics model (C-index, 0.65, P < 0.0001) or clinical predictors (C-index, 0.66; P < 0.0001). The multiparametric MR prognostic model also showed robustness in external validation (C-index, 0.70). Our results indicate that the incorporation of diffusion- and perfusion-weighted MR imaging into an MR radiomics model to improve prognostication in glioblastoma patients improved its performance over that achievable using clinical predictors alone.

Signal variance-based collateral index in DSC perfusion: A novel method to assess leptomeningeal collateralization in acute ischaemic stroke

As a determinant of the progression rate of the ischaemic process in acute large-vessel stroke, the degree of collateralization is a strong predictor of the clinical outcome after reperfusion therapy and may influence clinical decision-making. Therefore, the assessment of leptomeningeal collateralization is of major importance. The purpose of this study was to develop and evaluate a quantitative and observer-independent method for assessing leptomeningeal collateralization in acute large-vessel stroke based on signal variance characteristics in T2*-weighted dynamic susceptibility contrast (DSC) perfusion-weighted MR imaging (PWI). Voxels representing leptomeningeal collateral vessels were extracted according to the magnitude of signal variance in the PWI raw data time series in 55 patients with proximal large-artery occlusion and an intra-individual collateral vessel index (CVIPWI) was calculated. CVIPWI correlated significantly with the initial ischaemic core volume (rho = −0.459, p = 0.0001) and the PWI/DWI mismatch ratio (rho = 0.494, p = 0.0001) as an indicator of the amount of salvageable tissue. Furthermore, CVIPWI was significantly negatively correlated with NIHSS and mRS at discharge (rho = −0.341, p = 0.015 and rho = −0.305, p = 0.023). In multivariate logistic regression, CVIPWI was an independent predictor of favourable functional outcome (mRS 0–2) (OR = 16.39, 95% CI 1.42–188.7, p = 0.025). CVIPWI provides useful rater-independent information on the leptomeningeal collateral supply in acute stroke.

Utility of Dynamic Susceptibility Contrast Perfusion-Weighted MR Imaging and 11C-Methionine PET/CT for Differentiation of Tumor Recurrence from Radiation Injury in Patients with High-Grade Gliomas.

Both 11C-methionine PET/CT and DSC-PWI could be used to differentiate radiation injury from recurrent brain tumors. Our aim was to assess the performance of MET PET/CT and DSC-PWI for differentiation of recurrence and radiation injury in patients with high-grade gliomas and to quantitatively analyze the diagnostic values of PET and PWI parameters. Forty-two patients with high-grade gliomas were enrolled in this study. The final diagnosis was determined by histopathologic analysis or clinical follow-up. PWI and PET parameters were recorded and compared between patients with recurrence and those with radiation injury using Student t tests. Receiver operating characteristic and logistic regression analyses were used to determine the diagnostic performance of each parameter. The final diagnosis was recurrence in 33 patients and radiation injury in 9. PET/CT showed a patient-based sensitivity and specificity of 0.909 and 0.556, respectively, while PWI showed values of 0.667 and 0.778, respectively. The maximum standardized uptake value, mean standardized uptake value, tumor-to-background maximum standardized uptake value, and mean relative CBV were significantly higher for patients with recurrence than for patients with radiation injury. All these parameters showed a high discriminative power in receiver operating characteristic analysis. The optimal cutoff values for the tumor-to-background maximum standardized uptake value and mean relative CBV were 1.85 and 1.83, respectively, and corresponding sensitivities and specificities for the diagnosis of recurrence were 0.97 and 0.667 and 0.788 and 0.88, respectively. Areas under the curve for the tumor-to-background maximum standardized uptake value and mean relative CBV were 0.847 ± 0.077 and 0.845 ± 0.078, respectively. Combined assessment of the tumor-to-background maximum standardized uptake value and mean relative CBV showed the largest area under the curve (0.953 ± 0.031), with corresponding sensitivity and specificity of 0.848 and 1.0, respectively. Both 11C-methionine PET/CT and PWI are equally accurate in the differentiation of recurrence from radiation injury in patients with high-grade gliomas, and a combination of the 2 modalities could result in increased diagnostic accuracy.

Differentiation of High-grade Gliomas from Brain Metastases Using Tissue Similarity Maps (TSMs) Based Relative Cerebral Blood Volume Values

Background: Perfusion Weighted Imaging (PWI) has been used to differentiate the solitary metastases from high-grade glioma. However, the CBV value obtained from classical algorithm can be affected by a number of factors. Tissue Similarity Map (TSM) is a new algorithm depending solely on the signal intensity time course but does not require the use of Concentration Time Curve (CTC), which is different from the classical rCBV algorithm. Objective: The purpose of this study is to investigate the diagnostic utility of TSM based rCBV values in differentiating between high-grade gliomas and solitary metastases. Methods: The preoperative MR PWI studies of 30 patients with a solitary cerebral neoplasm were retrospectively analyzed. All PWI data were calculated for TSM algorithm with MATLAB 7.6 (Math Works, Natick, MA). The TSM based rCBV (rCBVTSM) were measured in the parenchyma of tumor and peritumoral regions. All specimens were histopathologically categorized as high-grade gliomas or metastases and were correlated with corresponding rCBVTSM values. Results: All PWI data could be post-processed by using the TSM post-processing software. The differences in the rCBVTSM-T between high-grade gliomas and metastases were not statistically significant (p=0.299). While the rCBVTSM-P of high-grade gliomas was higher than that of metastases (p=0.040). ROC curve analysis showed significant AUC of rCBVTSM-P for differentiating highgrade gliomas from metastases (p=0.020). The rCBVTSM-P threshold of 1.725 was found to be a significant cutoff value for high-grade glioma/metastases prediction with 0.619 sensitivity and 0.889 specificity. Conclusion: The rCBVTSM-P derived from MR PWI may be helpful in differentiating high-grade gliomas from solitary metastases. Keywords: TSM, perfusion imaging, cerebral blood volume, glioma, neoplasms metastasis, differentiation diagnosis.

Arterial spin labeling perfusion-weighted MR imaging: correlation of tumor blood flow with pathological degree of tumor differentiation, clinical stage and nodal metastasis of head and neck squamous cell carcinoma.

The prognostic parameters of head and neck squamous cell carcinoma (HNSCC) include the pathological degree of tumor differentiation, clinical staging, and presence of metastatic cervical lymph nodes. To correlate tumor blood flow (TBF) acquired from arterial spin labeling (ASL) perfusion-weighted MR imaging with pathological degree of tumor differentiation, clinical stage, and nodal metastasis of HNSCC. Retrospective analysis of 43 patients (31 male, 12 female with a mean age of 65years) with HNSCC that underwent ASL of head and neck and TBF of HNSCC was calculated. Tumor staging and metastatic lymph nodes were determined. The stages of HNSCC were stage 1 (n = 7), stage II (n = 12), stage III (n = 11) and stage IV (n = 13). Metastatic cervical lymph nodes were seen in 24 patients. The degree of tumor differentiation was determined through pathological examination. The mean TBF of poorly and undifferentiated HNSCC (157.4 ± 6.7mL/100g/min) was significantly different (P = 0.001) than that of well-to-moderately differentiated (142.5 ± 5.7mL/100g/min) HNSCC. The cut-off TBF used to differentiate well-moderately differentiated from poorly and undifferentiated HNSCC was 152mL/100g/min with an area under the curve of 0.658 and accuracy of 88.4%. The mean TBF of stages I, II (146.10 ± 9.1mL/100g/min) was significantly different (P = 0.014) than that of stages III, IV (153.33 ± 9.3mL/100g/min) HNSCC. The cut-off TBF used to differentiate stages I, II from stages III and IV was 148mL/100g/min with an area under the curve of 0.701 and accuracy of 69.8%. The TBF was higher in patients with metastatic cervical lymph nodes. The cut-off TBF suspect metastatic node was 147mL/100g/min with an area under the curve of 0.671 and accuracy of 67.4%. TBF is a non-invasive imaging parameter that well correlated with pathological degree of tumor differentiation, clinical stage of tumor and nodal metastasis of HNSCC.

The performance of MR perfusion-weighted imaging for the differentiation of high-grade glioma from primary central nervous system lymphoma: A systematic review and meta-analysis.

It is always a great challenge to distinguish high-grade glioma (HGG) from primary central nervous system lymphoma (PCNSL). We conducted a meta-analysis to assess the performance of MR perfusion-weighted imaging (PWI) in differentiating HGG from PCNSL. The heterogeneity and threshold effect were evaluated, and the sensitivity (SEN), specificity (SPE) and areas under summary receiver operating characteristic curve (SROC) were calculated. Fourteen studies with a total of 598 participants were included in this meta-analysis. The results indicated that PWI had a high level of accuracy (area under the curve (AUC) = 0.9415) for differentiating HGG from PCNSL by using the best parameter from each study. The dynamic susceptibility-contrast (DSC) technique might be an optimal index for distinguishing HGGs from PCNSLs (AUC = 0.9812). Furthermore, the DSC had the best sensitivity 0.963 (95%CI: 0.924, 0.986), whereas the arterial spin-labeling (ASL) displayed the best specificity 0.896 (95% CI: 0.781, 0.963) among those techniques. However, the variability of the optimal thresholds from the included studies suggests that further evaluation and standardization are needed before the techniques can be extensively clinically used.

Early perfusion MRI predicts survival outcome in patients with recurrent glioblastoma treated with bevacizumab and carboplatin.

Bevacizumab, an anti-angiogenic agent, is FDA-approved for use in patients with recurrent glioblastoma multiforme (rGBM). The radiologic evaluation of tumor response to bevacizumab is complex and there is no validated method of monitoring tumor vascularity during therapy. We evaluated perfusion-weighted MR imaging (PWI) in our cohort of patients enrolled in the CABARET trial, which examined the effectiveness of bevacizumab with or without carboplatin in patients with rGBM. Pre-treatment and early follow-up (4- and 8-week) PWI were used to calculate relative cerebral blood volume (rCBV) histogram statistics of the contrast-enhancing and FLAIR hyperintense tumor volumes. A novel rCBV measurement (load) was developed to estimate the total volume of perfused tumor blood vessels. Changes in all rCBV measures were examined for correlations with progression-free (PFS) and overall survival (OS). All of our 15 patients enrolled in the CABARET trial were included. Median PFS and OS were 23 and 45 weeks respectively. Kaplan-Meier analysis of pre-treatment PWI revealed an 18 week reduction in median OS in patients with high tumor rCBV (p = 0.031). Changes in rCBV measures, especially load, correlated significantly with PFS and OS at both follow-up time-points. Patients with the greatest reduction in rCBVload by 8-weeks of therapy had a significantly increased median OS (30 weeks; p = 0.013). PWI may be of significant clinical utility in managing patients with rGBM, particularly those treated with anti-angiogenic agents such as bevacizumab. These findings need to be confirmed prospectively in larger studies.

MR perfusion-weighted imaging in the evaluation of high-grade gliomas after treatment: a systematic review and meta-analysis.

Distinction between tumor and treatment related changes is crucial for clinical management of patients with high-grade gliomas. Our purpose was to evaluate whether dynamic susceptibility contrast-enhanced (DSC) and dynamic contrast enhanced (DCE) perfusion-weighted imaging (PWI) metrics can effectively differentiate between recurrent tumor and posttreatment changes within the enhancing signal abnormality on conventional MRI. A comprehensive literature search was performed for studies evaluating PWI-based differentiation of recurrent tumor and posttreatment changes in patients with high-grade gliomas (World Health Organization grades III and IV). Only studies published in the "temozolomide era" beginning in 2005 were included. Summary estimates of diagnostic accuracy were obtained by using a random-effects model. Of 1581 abstracts screened, 28 articles were included. The pooled sensitivities and specificities of each study's best performing parameter were 90% and 88% (95% CI: 0.85-0.94; 0.83-0.92) and 89% and 85% (95% CI: 0.78-0.96; 0.77-0.91) for DSC and DCE, respectively. The pooled sensitivities and specificities for detecting tumor recurrence using the 2 most commonly evaluated parameters, mean relative cerebral blood volume (rCBV) (threshold range, 0.9-2.15) and maximum rCBV (threshold range, 1.49-3.1), were 88% and 88% (95% CI: 0.81-0.94; 0.78-0.95) and 93% and 76% (95% CI: 0.86-0.98; 0.66-0.85), respectively. PWI-derived thresholds separating viable tumor from treatment changes demonstrate relatively good accuracy in individual studies. However, because of significant variability in optimal reported thresholds and other limitations in the existing body of literature, further investigation and standardization is needed before implementing any particular quantitative PWI strategy across institutions.