Perfusion-weighted Imaging Parameters Research Articles

Differentiation Between High-Grade Glioma and Brain Metastasis Using Cerebral Perfusion-Related Parameters (Cerebral Blood Volume and Cerebral Blood Flow): A Systematic Review and Meta-Analysis of Perfusion-weighted MRI Techniques.

Distinguishing high-grade gliomas (HGGs) from brain metastases (BMs) using perfusion-weighted imaging (PWI) remains challenging. PWI offers quantitative measurements of cerebral blood flow (CBF) and cerebral blood volume (CBV), but optimal PWI parameters for differentiation are unclear. To compare CBF and CBV derived from PWIs in HGGs and BMs, and to identify the most effective PWI parameters and techniques for differentiation. Systematic review and meta-analysis. Twenty-four studies compared CBF and CBV between HGGs (n = 704) and BMs (n = 488). Arterial spin labeling (ASL), dynamic susceptibility contrast (DSC), dynamic contrast-enhanced (DCE), and dynamic susceptibility contrast-enhanced (DSCE) sequences at 1.5 T and 3.0 T. Following the PRISMA guidelines, four major databases were searched from 2000 to 2024 for studies evaluating CBF or CBV using PWI in HGGs and BMs. Standardized mean difference (SMD) with 95% CIs was used. Risk of bias (ROB) and publication bias were assessed, and I2 statistic was used to assess statistical heterogeneity. A P-value<0.05 was considered significant. HGGs showed a significant modest increase in CBF (SMD = 0.37, 95% CI: 0.05-0.69) and CBV (SMD = 0.26, 95% CI: 0.01-0.51) compared with BMs. Subgroup analysis based on region, sequence, ROB, and field strength for CBF (HGGs: 375 and BMs: 222) and CBV (HGGs: 493 and BMs: 378) values were conducted. ASL showed a considerable moderate increase (50% overlapping CI) in CBF for HGGs compared with BMs. However, no significant difference was found between ASL and DSC (P = 0.08). ASL-derived CBF may be more useful than DSC-derived CBF in differentiating HGGs from BMs. This suggests that ASL may be used as an alternative to DSC when contrast medium is contraindicated or when intravenous injection is not feasible. Stage 2.

Predictive value of perfusion weighted imaging for early new lesions after stroke patients receive endovascular treatment.

Previous studies have focused on early new lesion-associated factors, but the differences in the perfusion status between the at-risk hypoperfusion areas with new lesions and the other hypoperfusion areas in stroke patients before thrombectomy is not clear. We investigated the value of perfusion-weighted imaging (PWI) in predicting early new lesions in patients after stroke. Fifty-five acute stroke patients who underwent diffusion-weighted imaging (DWI) and PWI before and after thrombectomy within 24 h were eligible. The PWI parameters of the core infarct areas (high signal tissue on the DWI), the at-risk hypoperfusion areas (hypoperfusion area with new lesions at follow-up PWI) and the other hypoperfusion areas of patients with new lesions were collected. Statistical analysis was performed to predict new lesions after stroke. The differences in the PWI parameters of the core infarct areas, the at-risk hypoperfusion areas and the other hypoperfusion areas were compared. Receiver operating characteristic (ROC) curve analysis was used to assess the predictive value of the PWI parameters (P<0.05) for the occurrence of new lesions in patients with acute stroke after thrombectomy. Fifty-five stroke patients were analyzed, including forty patients (72.73%) with new lesions and fifteen patients (27.27%) without new lesions. Acute stroke patients with new lesions had a longer mean transit time (MTT) and time to peak (TTP) in the at-risk hypoperfusion areas (11.95±3.29; 38.30±11.39) than in the other hypoperfusion areas (8.68±2.08; 29.76±6.86), both of which were significantly different (P<0.0001; P<0.0001, respectively). The ROC analysis showed that the sensitivity and specificity of MTT for predicting the occurrence of new lesions after stroke were 70.00% and 87.50%, respectively; the sensitivity and specificity of TTP were 70.00% and 80.00%, respectively. MTT and TTP may be useful in predicting early new lesions in acute stroke patients after thrombectomy.

Effects of "Tongdu Tiaoshen" acupuncture on cerebral blood flow in patients with high risk of cerebral ischemic stroke based on ASL and PWI technique

To observe the effects of "Tongdu Tiaoshen" acupuncture on cerebral blood flow in high-risk patients of cerebral ischemic stroke based on arterial spin labeling (ASL) and perfusion-weighted imaging (PWI), and to evaluate the clinical efficacy. A total of 180 patients with transient ischemic attacks (TIA) / minor ischemic stroke (MIS) were randomly divided into an acupuncture A group, an acupuncture B group and a medication group, 60 cases in each group. The patients in the acupuncture A group were treated with "Tongdu Tiaoshen" acupuncture at Baihui (GV 20), Fengfu (GV 16), Yamen (GV 15), Dazhui (GV 14), Shenzhu (GV 12), Zhiyang (GV 9), Mingmen (GV 4), Yaoyangguan (GV 3) and Jingjiaji (EX-B 2), once a day; the patients in the acupuncture B group were treated with identical acupoints but was given once every other day; the patients in the medication group were treated with oral administration of nimodipine tablets, 30 mg, three times daily. All the three groups were treated for four weeks. ASL and PWI, including relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), relative mean transit time (rMTT) and relative time to peak (rTTP), were conducted before and after treatment; the changes of the test indexes were compared before and after treatment. The clinical efficacy of the three groups was compared. Compared before treatment, the numbers of ASL normal perfusion in the 3 groups were significantly increased after treatment (all P<0.01); the number of ASL normal perfusion in the acupuncture A group was higher than that in the acupuncture B group (P<0.05), but was not significantly different from that in the medication group (P>0.05). Compared before treatment, rCBV and rCBF in the 3 groups were significantly increased after treatment (all P<0.01), and rMTT and rTTP were significantly reduced (all P<0.01). After treatment, rCBV and rCBF in the acupuncture A group were higher than those in the acupuncture B group (all P<0.05); the rMTT and rTTP in the acupuncture A group were lower than those in the acupuncture B group (all P<0.05); the differences of PWI parameters after treatment were not statistically significant between the acupuncture A group and medication group (all P>0.05). The total effective rate was 88.3% (53/60) in the acupuncture A group, 73.3% (44/60) in the acupuncture B group and 90.0% (54/60) in the medication group; the total effective rate in the acupuncture A group was superior to that in the acupuncture B group (P<0.05), but was not significantly different from that in the medication group (P>0.05). "Tongdu Tiaoshen" acupuncture could effectively improve the hypoperfusion of cerebral blood flow in patients with high risk of cerebral ischemic stroke, reduce the incidence of severe CIS; acupuncture for once a day is better than once every other day.

Intraoperative perfusion-weighted imaging in non-enhanced glioma surgery.

The objective of the present study was to observe and analyze the significance of perfusion-weighted imaging for guiding the operation implementation for non-enhanced glioma, and analyze the estimation of the histopathological grade of the non-enhanced glioma and the accuracy of the degree of malignancy degree before surgery. Fifty-six patients diagnosed with non-enhanced glioma through conventional magnetic resonance scanning were selected. Before surgery, conventional magnetic resonance scanning and perfusion-weighted imaging were performed on all patients. The property classification was performed with the perfusion-weighted imaging parameters: cerebral blood volume (CBV) and cerebral blood flow (CBF) before surgery. Surgery was performed on the 56 patients. Tumors were excised and processed for histopathological classification and semi-quantitative immunohistochemical analysis of vascular endothelial growth factor (VEGF) levels. Histology was compared after surgery and the classification accuracy rate was analyzed before surgery. Additionally, conventional magnetic resonance scanning and perfusion-weighted imaging were performed on 15 patients during surgery. We compared and analyzed the reference value of perfusion-weighted imaging before and during surgery. Residual diseased tissues were excised; histopathological examination was performed, and semi-quantitative immunohistochemical analysis of VEGF was performed. Regarding maximal magnetic resonance perfusion-weighted imaging measured before surgery, the CBV, CBF, and expression level of VEGF were positively correlated with the pathological grade of tumors. If the CBV and CBF values of the non-enhanced glioma were higher, the grade of malignancy was higher (P<0.01), and the positive expression rate of VEGF was higher (P<0.01). Magnetic resonance perfusion-weighted imaging can display vessel growth and distribution within non-enhanced gliomas before surgery, and effectively evaluate the histopathological grade and grade of malignancy, and provide accurate guidance for tumor resection during surgery.

Relative cerebral blood volume is a potential biomarker in late delayed radiation-induced brain injury.

To assess whether relative cerebral blood volume (rCBV) can provide information to reliably evaluate the stages of late delayed radiation-induced brain injury. Forty patients diagnosed with late delayed radiation-induced brain injury were enrolled. The patients were examined using a 1.5T magnetic resonance imaging (MRI) system equipped with an 8-channel head coil. An echo planar imaging (EPI) sequence was used in perfusion-weighted imaging (PWI). The location of 1H-MR spectroscopy scanning was acquired by a point-resolved spectroscopy sequence. Lesions of the temporal lobe were divided into one of two groups according to rCBV value: rCBV<1 (low rCBV [group 1; n = 45]); and rCBV>1 (elevated rCBV [group 2; n = 14]). PWI and MRS parameters, as well as morphological lesion types, in these two groups were compared. Morphological severity was assessed independently and agreed on by two imaging specialists (J.L. and H.X.S., with 16 and 24 years' experience, respectively). If necessary, a third imaging professor (Z.M.H.) with 30 years' experience resolved disagreement(s). Standards for evaluating morphological lesion types were based on previously published criteria. After testing the skewness of data, the Mann-Whitney U-test or Student's t-test was used, as appropriate. rCBV, relative cerebral blood flow (rCBF), and relative mean transit time (rMTT) in group 2 (n = 14) were significantly higher than in group 1 (n = 45) (rCBV: 1.21 ± 0.38 vs. 0.72 ± 0.32, respectively; P < 0.001; rCBF: 1.13 ± 0.02 vs. 0.74 ± 0.04, respectively; P < 0.001; rMTT: 1.10 ± 0.26 vs. 0.96 ± 0.20, P < 0.001). The levels of choline-containing compounds (CHO) / creatine (Cr) and CHO/N-acetylaspartate (NAA) in group 1 were significantly greater than in group 2 (CHO/Cr: 1.89 ± 1.83 vs. 1.22 ± 1.31, respectively; P = 0.016; CHO/NAA: 1.85 ± 3.50 vs. 1.17 ± 0.75, respectively; P = 0.022). More severe morphological lesions were present in lesions with low rCBV compared with elevated rCBV (overall severity: 7.00 ± 4.25 vs. 5.00 ± 5.13, respectively; P = 0.029). Elevated rCBV accompanied by a more conservative metabolic pattern and milder lesion(s) may represent a less advanced stage in the development of late delayed radiation-induced brain injury. 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1112-1118.

An evaluation of morphological and functional multi-parametric MRI sequences in classifying non-muscle and muscle invasive bladder cancer.

Our goal is to determine the ability of multi-parametric magnetic resonance imaging (mpMRI) to differentiate muscle invasive bladder cancer (MIBC) from non-muscle invasive bladder cancer (NMIBC). Patients underwent mpMRI before tumour resection. Four MRI sets, i.e. T2-weighted (T2W) + perfusion-weighted imaging (PWI), T2W plus diffusion-weighted imaging (DWI), T2W + DWI + PWI, and T2W + DWI + PWI + dif-fusion tensor imaging (DTI) were interpreted qualitatively by two radiologists, blinded to histology results. PWI, DWI and DTI were also analysed quantitatively. Accuracy was determined using histopathology as the reference standard. A total of 82 tumours were analysed. Ninety-six percent of T1-labeled tumours by the T2W + DWI + PWI image set were confirmed to be NMIBC at histopathology. Overall accuracy of the complete mpMRI protocol was 94% in differentiating NMIBC from MIBC. PWI, DWI and DTI quantitative parameters were shown to be significantly different in cancerous versus non-cancerous areas within the bladder wall in T2-labelled lesions. MpMRI with DWI and DTI appears a reliable staging tool for bladder cancer. If our data are validated, then mpMRI could precede cystoscopic resection to allow a faster recognition of MIBC and accelerated treatment pathways. • A critical step in BCa staging is to differentiate NMIBC from MIBC. • Morphological and functional sequences are reliable techniques in differentiating NMIBC from MIBC. • Diffusion tensor imaging could be an additional tool in BCa staging.

Predictive values of diffusion-weighted imaging and perfusion-weighted imaging in evaluating the efficacy of transcatheter arterial chemoembolization for hepatocellular carcinoma.

This study explored the predictive values of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) in evaluating the efficacy of transcatheter arterial chemoembolization (TACE) for patients with hepatocellular carcinoma (HCC). A total of 118 HCC patients treated with TACE were selected from April 2013 to November 2015. T1-weighted imaging (T1WI)/T2-weighted imaging (T2WI), DWI, and PWI were performed on all patients before and after TACE. Efficacy was evaluated according to modified Response Evaluation Criteria in Solid Tumors 1.1. Receiver operating characteristic curve was used to evaluate the diagnostic power of quantitative DWI and PWI parameters in evaluating the efficacy of TACE for HCC patients. Among the 118 HCC patients, there were 17 cases (14.4%) with complete response, 50 cases (42.4%) with partial response, 28 cases (23.7%) with stable disease, and 23 cases (19.5%) with progressive disease. There were 67 patients in the effective group (complete response + partial response) and 51 patients in the ineffective group (stable disease + progressive disease). Before TACE, there were significant differences in maximum tumor diameter (MTD), apparent diffusion coefficient (ADC), slow ADC (Dslow), fast ADC (Dfast), transfer constant of vessel at the maximum level (Ktrans), and rate constant of backflux (Kep) between the effective and ineffective groups (all P<0.05). After TACE, the effective group exhibited lower MTD, Dfast, and Kep and higher ADC and Dslow than the ineffective group (all P<0.05). Tumor regression rate negatively correlated with MTD, Ktrans, Kep, and Dfast but positively correlated with ADC and Dslow. Receiver operating characteristic curve analysis suggested that the area under the curve of ADC, Dslow, Dfast, Ktrans, and Kep were 0.869, 0.833, 0.812, 0.802, and 0.809, respectively. In conclusion, these results suggest that quantitative DWI and PWI parameters might be useful in evaluating the efficacy of TACE in the treatment of HCC patients.

The Role of Bolus Delay and Dispersion in Predictor Models for Stroke

In combination with diffusion-weighted imaging, perfusion-weighted imaging parameters are hypothesized to detect tissue at risk of infarction in patients with acute stroke. Recent studies have suggested that in addition to perfusion deficits, vascular flow parameters indicating bolus delay and/or dispersion may also contain important predictive information. This work investigates the infarct risk associated with delay/dispersion using multiparametric predictor models. Predictor models were developed using specific combinations of perfusion parameters calculated using global arterial input function deconvolution (where perfusion is biased by dispersion), local arterial input function deconvolution (where perfusion has minimal dispersion bias), and parameters approximating bolus delay/dispersion. We also compare predictor models formed using summary parameters (which primarily reflect delay/dispersion). The models were trained on 15 patients with acute stroke imaged at 3 to 6 hours. The global arterial input function models performed significantly better than their local arterial input function counterparts. Furthermore, in a paired comparison, the models including the delay/dispersion parameter performed significantly better than those without. There was no significant difference between the best deconvolution model and the best summary parameter model. Delay and dispersion information is important to achieve accurate infarct prediction in the acute time window.

PWI-MRI and contrast extravasation in brain AVM help to estimate angiogenic activity

The aim of this study is to investigate perfusion characteristics of brain arteriovenous malformation (AVM) by means of MRI perfusion-weighted imaging (PWI). Forty-three patients with brain AVM were prospectively included and investigated by PWI-MRI. Diagnosis of type of disease was made by angiogram. According to angiographic features, the study group was classified in three groups: two groups of patients with classical AVM (group 1 with few or no angiogenic feature (13 patients) and group 2 with many angiogenic features (18 patients)) and one group (group 3) which included patients with cerebral proliferative angiopathy (CPA; 12 patients). Twenty-one patients had never been treated endovascularly for their AVM and 22 patients received partial treatment by endovascular embolisation. Through PWI, corrected cerebral blood volume (CBVc), mean transit time (MTT), and percentage of microvascular leakage (MVL) as an indirect measure of permeability were assessed. The three patient groups did not differ significantly in baseline and clinical parameters. CBVc, MTT, and MVL differed significantly between the three groups (p = 0.003, p = 0.04, p = 0.01, respectively), with the lowest mean values found in group 1 and the highest in group 3. Mean MVL was 11.4 in group 1, 18.6 in group 2, and 21.9 in group 3. MRI can demonstrate differences in PWI parameters among patients with classical AVM and CPA, which are related to angiographic features of these AVMs. Through PWI, the level of angiogenic activity in AVMs may be monitored.

Assessment of baseline hemodynamic parameters within infarct progression areas in acute stroke patients using perfusion-weighted MRI

The value of perfusion MRI for identifying the tissue at risk has been questioned. Our objective was to assess baseline perfusion-weighted imaging parameters within infarct progression areas. Patients with anterior circulation stroke without early reperfusion were included from a prospective MRI database. Sequential MRI examinations were performed on admission, 2-3h (H2), 2-3days (D2), and between 15 and 30days after the initial MRI. Maps of baseline time-to-peak (TTP), mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were calculated. Lesion extension areas were defined as pixels showing de novo lesions between each MRI and were generated by subtracting successive lesion masks: V(0), baseline diffusion-weighted imaging (DWI) lesion; V(1), lesion extension between baseline and H2 DWI; V(2), lesion extension from H2 to D2 DWI; and V(3), lesion extension from D2 DWI to final FLAIR. Repeated measures analysis was used to compare hemodynamic parameters within the baseline diffusion lesion and subsequent lesion extension areas. Thirty-two patients were included. Baseline perfusion parameters were significantly more impaired within the acute DWI lesion compared to lesion extension areas (TTP, p < 0.0001; MTT, p < 0.0001; CBF p < 0.0001; CBV, p < 0.0001). A significant decrease in MTT (p = 0.01) and TTP (p = 0.01) was found within successive lesion growth areas. A decreasing gradient of severity for TTP and MTT was observed within successive infarct growth areas.

Changes in Perfusion-Weighted Magnetic Resonance Imaging after Carotid Angioplasty with Stent

Carotid artery stenosis due to arteriosclerosis increases the risk of cerebral ischemia via embolic phenomena or reduced blood flow. The changes in cerebral perfusion that may occur after treatment are not clearly understood. This study evaluated the changes in cerebral microcirculation following carotid angioplasty with stenting (CAS) under cerebral protection with filters using ultrafast gradient echo (GRE) perfusion weighted imaging (PWI) with magnetic resonance imaging (MRI). Prospectively, 21 cervical carotid stenosis patients, mean age 69.95 years, underwent MRI 12 h before and 72 h after CAS. PWI parameters were collected for statistical analysis: cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP). Statistical analysis was applied to absolute parameters and to values normalized against those from the contralateral parenchyma. The main finding of this study was improved hemodynamics for the normalized data after CAS, shown by reduced MTT (p<0.001) and TTP (p=0.019) in the territory fed by the middle cerebral artery ipsilateral to the CAS. Absolute data showed increased blood volume in the cerebral hemispheres after CAS, which was more accentuated on the stent side (p=0.016) than the contralateral side (p=0.029). Early improvements in cerebral perfusion, mainly seen in the normalized data, were clearly demonstrated in the timing parameters - TTP & MTT - after CAS.

Tumor regrowth between surgery and initiation of adjuvant therapy in patients with newly diagnosed glioblastoma

To assess incidence and degree of regrowth in glioblastoma between surgery and radiation therapy (RT) and to correlate regrowth with presurgical imaging and survival, we examined images of 32 patients with newly diagnosed glioblastoma who underwent MR spectroscopic imaging (MRSI), perfusion-weighted imaging (PWI), and diffusion-weighted imaging (DWI) prior to surgery, after surgery, and prior to RT/temozolomide. Contrast enhancement (CE) in the pre-RT MR image was compared with postsurgical DWI to differentiate tumor growth from postsurgical infarct. MRSI and PWI parameters were analyzed prior to surgery and pre-RT. Postsurgical MRI indicated that 18 patients had gross total and 14 subtotal resections. Twenty-one patients showed reduced diffusion, and 25 patients showed new or increased CE. In eight patients (25%), the new CE was confined to areas of postsurgical reduced diffusion. In the other 17 patients (53%), new CE was found to be indicative of tumor growth or a combination of tumor growth and surgical injury. Higher perfusion and creatine within nonenhancing tumor in the presurgery MR were associated with subsequent tumor growth. High levels of choline and reduced diffusion in pre-RT CE suggested active metabolism and tumor cell proliferation. Median survival was 14.6 months in patients with interim tumor growth and 24 months in patients with no growth. Increased volume or new onset of CE between surgery and RT was attributed to tumor growth in 53% of patients and was associated with shorter survival. This suggests that reducing the time between surgery and adjuvant therapy may be important. The acquisition of metabolic and physiologic imaging data prior to adjuvant therapy may also be valuable in assessing regions of new CE and nonenhancing tumor.