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Objective:
Glioma classification and characterization may be facilitated by a multiparametric approach of perfusion metrics, which could not be achieved by conventional MRI alone. Our aim is to explore the potential of relative percentage signal intensity recovery (rPSR) values, in addition to relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) of first-pass T2* dynamic susceptibility contrast (DSC) perfusion MRI, in differentiating high- and low-grade glioma.Methods:
This prospective study included 39 patients with low-grade and 25 patients with high-grade glioma. rPSR, rCBV and rCBF were calculated from the first-pass T2* DSC perfusion MRI. rPSR was calculated using standard software and validated with dedicated perfusion metrics analysis software. The statistical analysis was performed using analysis of variance and receiver operating characteristic (ROC) curves.Results:
Variation in rPSR, rCBV and rCBF values between low- and high-grade gliomas were statistically significant (p < 0.005). The ROC curve analysis for each of them yielded 96% sensitivity and 71.8% specificity; 88% sensitivity and 69.2% specificity; and 72% sensitivity and 66.7% specificity. The area under the curve (AUC) from the ROC curve analysis yielded 0.893, 0.852 and 0.702 for rPSR, rCBV and rCBF, respectively. The rPSR calculation with the validation software yielded 92.3% sensitivity and 72% specificity with an AUC of 0.864.Conclusion:
rPSR inversely correlates while rCBV and rCBF values directly correlate with the tumour grade. Furthermore, the overall diagnostic performance of rPSR is better than rCBV and rCBF values.Advances in knowledge:
rPSR of T2* DSC perfusion is an indicator of blood–brain barrier status and lesion leakiness, which has not been explored yet compared with the usual haemodynamic parameters, rCBV and rCBF.Gliomas, the most common primary brain tumour of the brain, are heterogeneous, showing highly varied histopathological features during malignant transformation of the tumour reflecting alterations in the tumour vasculature.1 The broad category of glioma represents approximately 30% of all the tumours. Low-grade astrocytomas (60–70%) and oligodendrogliomas (10–30%) are two common subtypes of low-grade gliomas. Among them, glioblastoma and astrocytoma account for 75% of gliomas.2 With the advent of advanced imaging technologies, heterogeneity in gliomas such as neovascularization, angiogenesis, loss of blood–brain barrier (BBB) integrity, tortuousness, disorganized and highly permeable vessels may be non-invasively measured with the help of perfusion imaging.3–5 Dynamic susceptibility contrast (DSC) perfusion MRI is a widely accepted tool for evaluating the haemodynamic characteristics of the brain, which are of great interest since it helps in assessing the malignancy of the tumour. The common haemodynamic parameters assessed using perfusion MRI are relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF).6–8 In this study, we use a comparatively newer parameter, relative percentage signal intensity recovery (rPSR), whose potential has not been exploited to its best for haemodynamic calculations, even though this parameter has shown promise in the differentiation of brain tumours.9–11 PSR is the percentage of the signal intensity recovered at the end of the first pass of the contrast agent with respect to the pre-contrast baseline signal intensity. After the administration of the contrast agent, there is a sudden decrease in the signal intensity owing to the variation in the local magnetic field leading to T2* decay, which is seen as a dip in the mean signal intensity–time curve, and then the signal returns towards the baseline.9–11The tumour rCBV provides information about the tumour blood levels and degree of angiogenesis but fails to provide information regarding capillary permeability. This drawback of DSC-MR perfusion imaging can be addressed by evaluating the rPSR obtained from the signal intensity–time curve formed at the end of the first pass of contrast agent in DSC-MR perfusion imaging.9,10 Previous studies have observed that the contrast agent leakage, size of the extravascular space and the rate of blood flow that reflects the alterations in capillary permeability are related to rPSR.10,11 There are reports which state that information regarding capillary permeability and lesion leakiness can be gathered from the signal intensity–time curve obtained from the first-pass T2* DSC perfusion. Usually, this is performed using dynamic contrast-enhanced perfusion MRI, which involves additional scan time and also post-processing assumptions and extrapolations.9–11Lupo et al4 was the first to report the characterization of high-grade gliomas using the PSR and peak height. rPSR is the only parameter among the different perfusion metrics which takes into account the leakage factor for the characterization of heterogeneity of brain tissues, compared with the other two parameters rCBV and rCBF where the leakage is neglected during the evaluation. The rPSR values of lower grade gliomas have not been explored, and hence an effort to differentiate between high- and low-grade gliomas using this new parameter will be advantageous. Hence, in the present study, we have evaluated all the parameters rPSR, rCBV and rCBF of low- and high-grade gliomas to find the potential of rPSR to differentiate different grades of glioma over the other two conventionally used parameters rCBV and rCBF. rPSR values were evaluated using two different standard software programs. Furthermore, we have performed a test for correlation between these parameters. 相似文献Idiopathic junctional ectopic tachycardia (JET) is typically refractory to antiarrhythmic agents. Catheter ablation for JET is feasible but is associated with high risk of unintended atrioventricular (AV) block. There is limited data on the appropriate procedural technique and clinical outcomes with catheter ablation for idiopathic JET in adults.
MethodsThis is a multicenter, retrospective study of all adult patients (age?≥?18 years) who underwent catheter ablation for idiopathic JET. Patient, procedural characteristics, and long-term outcomes were evaluated.
ResultsFifteen patients [radiofrequency ablation (RF)?=?14 and cryoablation?=?1) were treated with catheter ablation. The median age was 58 years with 67% males. All patients underwent mapping of the right atrium and the aortic cusps prior to energy delivery. The location of earliest activation in relation to the atrioventricular (AV) node was postero-superior in 73% (11/15), posterior in 13% (2/15), and superior in 13% (2/15) respectively. Acute success was 100%. Arrhythmia recurrence occurred in 53% (8/15) all of whom underwent a repeat ablation. High-grade AV block requiring permanent pacemaker occurred in 20% (3/15). At 12-month follow-up in the redo-ablation group, 37.5% (3/8) had recurrence of the arrhythmia two of which underwent a third ablation procedure.
ConclusionCatheter ablation of idiopathic JET in adults is associated with a high rate of recurrence requiring multiple procedures and high risk of AV block requiring a permanent pacemaker. Mapping and ablation of the non-coronary cusp can be considered as the arrhythmia was controlled in 3 patients with no inadvertent AV block.
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