Quantitative Characterization of Tumoural Leakage Phenomena Using Dynamic Susceptibility Contrast Perfusion Imaging

Purpose:Microvascular Leakiness varies between tumours. Extravascular leakage, hitherto the Achilles heel of Dynamic-Susceptibility-Contrast-Perfusion-Weighted-Imaging (DSC-PWI), has lately been quantified by leakage coefficient “K2”. To evaluate K2's diagnostic potential for differentiation of PCNSL, GBM and Mets and assess its relationships with other DSC-PWI metrics.Methods:Retrospective analysis of T2*-weighted DSC-PWI of PCNSL, Mets (n=10 each )and GBM n=16) was performed using a “Leakage Correction” model to generate K2 , uncorrected relative CBV (rCBVucor) and corrected rCBV (rCBVcor). Peak Signal Recovery (PSR) was calculated. Group-level statistical comparisons was made.Results:All PCNSL showed high-magnitude-positive K2 value with mean [SD] 846.1[462] while Mets showed high-magnitude-negative K2 value with mean [SD] -754[546]. In contrast, GBM showed varied values (overall with lower magnitude and positive) of K2 with mean [SD] 391.9[294.1]. The intergroup differences in K2 were statistically different (P 0.000). Lesion K2 (magnitude) exhibited a significant strong positive correlation with the magnitude of CBV correction (ρ 0.63) and with PSR (ρ 0.70). Conclusion:PCNSL had greater high-magnitude-positive-K2 compared with other tumour groups, while Mets were notable for a high-magnitude-negative-K2. K2 parameter obtained from T2*-weighted DSC technique characterizes and quantifies microvascular leakage of contrast and thus provides an alternative means of measuring permeability in tumours. K2 quantification adds adjunctive value to pre-operative discrimination of intra-axial neoplasms. Given the widespread acceptance that DSC-PWI has, K2 holds promise as an attractive alternative to (the methodologically challenging) DCE-PWI-derived permeability metric, Ktrans.

Global Impairment of Cerebral Perfusion Measured using Dynamic Susceptibility Contrast Perfusion-Weighted Imaging in Out-of-Hospital Cardiac Arrest Survivors: A Prospectively Preliminary Study

Background: Dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI) is useful for measuring cerebral perfusion (CP). This study aimed to assess global impairment and the prognostic performance of CP parameters measured by DSC-PWI in out-of-hospital cardiac arrest (OHCA) survivors.Methods: This is a single-centre, prospective observational study. OHCA survivors who underwent DSC-PWI within 6 h after restoration of spontaneous circulation were enrolled. CP parameters (cerebral blood volume [CBV], cerebral blood flow [CBF], mean transit time [MTT], time to peak [TTP], and time to the maximum of the residue function [Tmax]) were quantified by normalisation + leakage correction (LC) or by arterial input function (AIF) + LC. The primary outcome was survival to discharge; subjects who died due to withdrawal of life-sustaining therapy or who were diagnosed with brain death (BD) were included in non-survival. The secondary outcome was 6-months neurological outcome. CP parameters were compared across groups, and receiver operating characteristic (ROC) curves were constructed to assess prognostic performances.Results: Thirty-one subjects (male, 20; 64.5%) participated. Relative CBV (rCBV) and CBF (rCBF) quantified by normalisation + LC were significantly higher in the non-survival group (p=0.02 and p=0.03, respectively). The area under the ROC curves (AUROCs) and 100% specific sensitivities for non-survival were 0.75/31.3% and 0.73/25.0%, respectively. MTT and Tmax quantified by AIF + LC were significantly higher in non-survival (p=0.01 and p=0.01, respectively). Their AUROCs and 100% specific sensitivities were 0.77/56.3% and 0.76/43.8%, respectively. rCBV and rCBF quantified by normalisation + LC were significantly higher in the poor neurological outcome group (p<0.01 and p=0.02, respectively). The AUROCs and 100% specific sensitivities for poor neurological outcome were 0.81/23.8% and 0.77/19.1%, respectively. Tmax quantified by AIF + LC was significantly higher in poor neurological outcome (p=0.04). Its AUROC and 100% specific sensitivity were 0.74/33.3%.Conclusion: Hyperaemia and delayed CP were present in the non-survival and poor neurological outcome groups. MTT quantified by AIF + LC could be the most powerful parameter for predicting mortality or BD in OHCA survivors at an early stage of post cardiac arrest care. AIF may be more appropriate as quantifying method for CP in OHCA survivors than normalisation.