Mean Transit Time Values Research Articles

Brain perfusion alterations in tick-borne encephalitis—preliminary report

BackgroundMagnetic resonance imaging (MRI) changes in tick-borne encephalitis (TBE) are non-specific and the pathophysiological mechanisms leading to their formation remain unclear. This study investigated brain perfusion in TBE patients using dynamic susceptibility-weighted contrast-enhanced magnetic resonance perfusion imaging (DSC-MRI perfusion). MethodsMRI scans were performed for 12 patients in the acute phase, 3–5days after the diagnosis of TBE. Conventional MRI and DSC-MRI perfusion studies were performed. Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) parametric maps were created. The bilateral frontal, parietal, and temporal subcortical regions and thalamus were selected as regions of interest. Perfusion parameters of TBE patients were compared to those of a control group. ResultsThere was a slight increase in CBF and CBV, with significant prolongation of TTP in subcortical areas in the study subjects, while MTT values were comparable to those of the control group. A significant increase in thalamic CBF (p<0.001) and increased CBV (p<0.05) were observed. Increased TTP and a slight reduction in MTT were also observed within this area. ConclusionsThe DSC-MRI perfusion study showed that TBE patients had brain perfusion disturbances, expressed mainly in the thalami. These results suggest that DSC-MRI perfusion may provide important information regarding the areas affected in TBE patients.

Orbital hemangiomas: capabilities of modern neuroradiological diagnostics

In the period from 2010 to 2016. 14 patients with cavernous hemangioma (CH) and 2 patients with capillary hemangioma (CapH) of the orbit were examined. The age of CH patients varied from 17 to 67 years (median, 53 years); 8 females and 6 males. The age of CapH patients was 35 and 54 years. All patients underwent surgery with subsequent histological verification. CT-perfusion was performed in 10 CH patients and 2 CapH patients according to a developed low-dose protocol (80 kV, 200 mAs, tscan=40 s) with allowance for a target localizer (80 kV, 120 mAs) and at a maximum radiation dose of not more than 4.0 mZv. Neoplasm microcirculation was quantitatively assessed by calculating hemodynamic parameters: blood flow velocity (BFV), blood volume (BV), and mean transit time (MTT). MRI without and with contrast enhancement was performed in 11 CH patients and 2 CapH patients according to the ophthalmologic protocol (Signa GE, 3.0 T) accepted at the Institute: without contrast enhancement - T1, T2, and T2-FLAIR modes, T1 and T2 with a Fat Sat technique at a scan thickness of 3 mm, and DWI MRI; contrast enhancement - T1 (three projections) mode, including the Fat Sat technique. SWAN (n=2) and non-contrast MR perfusion ASL (n=3) were also used. Diffusion-weighted images (DWI) were processed with calculation of the apparent diffusion coefficient (ACD). In all CH patients, CT-perfusion revealed low perfusion parameters of blood flow: BVCH=0.86±0.37 mL/100 g, BFVCH= 4.89±2.01 mL/100 g/min with a high mean transit time MTTCH=10.13±3.05 s compared to the same parameters of blood flow in the normal white matter: CBVNormWM=1.63±2.22 mL/100 g, CBFVNormWM=9.72±3.13 mL/100 g/min, and MTTNormWM=6.76±2.78 s. In CapH cases, significantly increased blood flow velocity and volume values and a low MTT value in the tumor were observed: BVCapH=10.30±4.10 mL/100 g, BFVCapH=119.72±53.13 mL/100 g/min, and MTTCapH=4.35±1.79 s. In the case of orbital hemangiomas, optimal MRI modes were T1 and T2 with the Fat Sat technique, a scan thickness of 3 mm, and intravenous contrast enhancement. The revealed pattern of contrast agent accumulation by CH, initially in the central part and then in the periphery, may be a useful radiographic sign in the differential diagnosis with other orbital tumors. Modern CT- and MRI-based diagnostics of orbital hemangiomas provides not only the exact location, size, and spread of the lesion but also reveals the characteristic structural features of these tumors, and the use of perfusion techniques visualizes hemodynamics of the tumors. CT-perfusion-based hemodynamic parameters of cavernous hemangiomas typical of this type of hemangiomas may be used in the differential diagnosis with other tumors of this location. The use of contrast enhancement and the Fat Sat technique with a scan thickness of not more than 3 mm is optimal for MRI diagnostics of orbital hemangiomas.

X-ray angiography perfusion imaging with an intra-arterial injection: comparative study with 15O-gas/water positron emission tomography

BackgroundX-ray angiography perfusion (XAP) is a perfusion imaging technique based on conventional DSA.ObjectiveIn this study, we aimed to validate parameters derived from XAP by comparing them with 15O-gas/water positron emission...

Slice-accelerated gradient-echo echo planar imaging dynamic susceptibility contrast-enhanced MRI with blipped CAIPI: effect of increasing temporal resolution.

To assess the influence of high temporal resolution on the perfusion measurements and image quality of perfusion maps, by applying simultaneous-multi-slice acquisition (SMS) dynamic susceptibility contrast-enhanced (DSC) magnetic resonance imaging (MRI). DSC-MRI data using SMS gradient-echo echo planar imaging sequences in 10 subjects with no intracranial abnormalities were retrospectively analyzed. Three additional data sets with temporal resolution of 1.0, 1.5, and 2.0s were created from the raw data sets of 0.5s. Cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), time to peak (TTP), and time to maximum tissue residue function (T max) measurements were performed, as was visual perfusion map analysis. The perfusion parameter for temporal resolution of 0.5s (reference) was compared with each synthesized perfusion parameter. CBF, MTT, and TTP values at temporal resolutions of 1.5 and 2.0s differed significantly from the reference. The image quality of MTT, TTP, and T max maps deteriorated with decreasing temporal resolution. The temporal resolution of DSC-MRI influences perfusion parameters and SMS DSC-MRI provides better image quality for MTT, TTP, and T max maps.

Characteristics of cerebral hemodynamics assessed by CT perfusion in moyamoya disease

Due to the recent development of multidetector row computed tomography (CT), hemodynamic parameters can now be conveniently obtained with CT perfusion. The purpose of this study is to characterize the hemodynamic parameters of CT perfusion in moyamoya disease, and to discuss the differences in collateral circulation between moyamoya disease and atherosclerotic disease. A total of 16 hemispheric sides of 15 patients with moyamoya disease and 10 hemispheric sides of 9 patients with atherosclerotic disease who underwent bypass surgery were included. CT perfusion was performed with 123I-IMP SPECT. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) values obtained by CT perfusion using standard singular value decomposition as the deconvolution algorithm in moyamoya disease were calculated. Preoperative values of these parameters were compared with those of atherosclerotic disease. Then, the postoperative changes of these parameters were analyzed. In the impaired side, CBF as measured by CT perfusion was correlated with that measured by 123I-IMP SPECT. In moyamoya disease, CBV as measured by CT perfusion was significantly increased compared to in atherosclerotic disease, yet CBF was significantly decreased in atherosclerotic disease. Postoperatively, the asymmetry ratios of MTT were significantly improved, especially in atherosclerotic disease compared with moyamoya disease. On CT perfusion, the parameters included transit time and arrival time. CBV increase in moyamoya disease and postoperative improvement of MTT, especially in atherosclerotic disease, were unique characteristics in each. This might be due to the difference of collateral circulation and compensatory mechanisms between moyamoya disease and atherosclerotic disease.

The effect of scan interval and bolus length on the quantitative accuracy of cerebral computed tomography perfusion analysis using a hollow-fiber phantom.

The shuttle scan technique is expected to extend scan range in cerebral computed tomography (CT) perfusion by 16- or 64-row multidetector CT (MDCT), but it may affect quantitative accuracy. This study aims to evaluate the effect of long scan interval and bolus length on the quantitative accuracy of perfusion indices using an innovative hollow-fiber phantom.We used an originally developed hollow-fiber hemodialyzer covered with polyurethane resin as a perfusion phantom. We scanned the phantom during various scan intervals (1-13s) and bolus injection lengths (5, 10, 15, and 20s), and evaluated cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP). We verified the influence on measured values using a two-way analysis of variance (ANOVA). All measured CBF values were smaller than the theoretical CBF values, and all the measured MTT values were larger that the theoretical MTT values (95% confidence interval). Extended scan intervals resulted in more overestimation of MTT and more underestimation of CBF (p<0.001). CBV is not affected by the change in scan interval (p<0.001), and a longer bolus length improved the underestimation of CBV (p<0.001). Extended scan intervals resulted in the loss of quantitative accuracy in MTT, even with longer bolus injection length, while quantitative CBF values were underestimated and TTP values overestimated. The CBV measurement was not affected by the change in scan interval, and a longer bolus injection improved the accuracy of these measurements.

CT Perfusion evaluation of gastric cancer: correlation with histologic type

To prospectively evaluate if the perfusion parameters of gastric cancer can provide information on histologic subtypes of gastric cancer. We performed preoperative perfusion CT (PCT) and curative gastrectomy in 46 patients. PCT data were analysed using a dedicated software program. Perfusion parameters were obtained by two independent radiologists and were compared according to histologic type using Kruskal-Wallis, Mann-Whitney U test and receiver operating characteristic analysis. To assess inter-reader agreement, we used intraclass correlation coefficient (ICC). Inter-reader agreement for perfusion parameters was moderate to substantial (ICC = 0.585-0.678). Permeability surface value of poorly cohesive carcinoma (PCC) was significantly higher than other histologic types (47.3ml/100g/min in PCC vs 26.5ml/100g/min in non-PCC, P < 0.001). Mean transit time (MTT) of PCC was also significantly longer than non-PCC (13.0s in PCC vs 10.3s in non-PCC, P = 0.032). The area under the curve to predict PCC was 0.891 (P < 0.001) for permeability surface and 0.697 (P = 0.015) for MTT. Obtaining perfusion parameters from PCT was feasible in gastric cancer patients and can aid in the preoperative imaging diagnosis of PCC-type gastric cancer as the permeability surface and MTT value of PCC type gastric cancer were significantly higher than those of non-PCC. • Obtaining perfusion parameters from PCT was feasible in patients with gastric cancer. • Permeability surface and MTT were significantly higher in poorly cohesive carcinoma (PCC). • Permeability surface, MTT can aid in the preoperative imaging diagnosis of PCC.

Correlation between Clinical Presentations and Hemodynamic Parameters Measured by Dynamic Susceptibility Contrast Magnetic Resonance Imaging in Adult Patients with Moyamoya Disease

The examination of cerebral hemodynamics is indispensable for the clinical management of patients with moyamoya disease (MMD). In this study, we examined the correlation between clinical presentations and hemodynamic parameters measured by dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) in adult patients with MMD. One hundred fifty-seven hemispheres in 122 adult patients with MMD were examined by DSC-MRI to measure the regional relative cerebral blood volume (CBV) and relative mean transit time (MTT). The patients were divided into 4 groups based on their clinical presentations: a nonsymptomatic (NS), hemorrhagic (H), infarction (I), and transient ischemic attack (T) group. The regional CBV and MTT values were compared among the 4 groups. The relative value of CBV was significantly higher in groups T and I than in the NS group (P < .01). The CBV of group H was higher than that of the NS group only in the frontal lobe cortex. There were no significant statistical differences among the 3 symptomatic groups. Prolongation of the MTT in comparison with the cerebellum (MTT delay) was significantly higher in groups T and I than in the NS group in all regions of the cerebral cortex (P < .05). The MTT delay was significantly lower in group H than in group T in the frontal lobe and the Rolandic area (P < .05). Hemodynamic factors measured by DSC-MRI reflected the variable clinical presentations of patients with MMD. DSC-MRI is a useful modality for evaluating the clinical conditions of individual adult patients with MMD.

Consideration of the Intracranial Pressure Threshold Value for the Initiation of Traumatic Brain Injury Treatment: A Xenon CT and Perfusion CT Study.

Monitoring of intracranial pressure (ICP) is considered to be fundamental for the care of patients with severe traumatic brain injury (TBI) and is routinely used to direct medical and surgical therapy. Accordingly, some guidelines for the management of severe TBI recommend that treatment be initiated for ICP values >20mmHg. However, it remained to be accounted whether there is a scientific basis to this instruction. The purpose of the present study was to clarify whether the basis of ICP values >20mmHg is appropriate. We retrospectively reviewed 25 patients with severe TBI who underwent neuroimaging during ICP monitoring within the first 7days. We measured cerebral blood flow (CBF), mean transit time (MTT), cerebral blood volume (CBV), and ICP 71 times within the first 7days. Although the CBF, MTT, and CBV values were not correlated with the ICP value at ICP values ≤20mmHg, the CBF value was significantly negatively correlated with the ICP value (r=-0.381, P<0.05) at ICP values >20mmHg. The MTT value was also significantly positively correlated with the ICP value (r=0.638, P<0.05) at ICP values >20mmHg. The cerebral circulation disturbance increased with the ICP value. We demonstrated the cerebral circulation disturbance at ICP values >20mmHg. This study suggests that an ICP>20mmHg is the threshold to initiate treatments. An active treatment intervention would be required for severe TBI when the ICP was >20mmHg.

Quantitative accuracy of computed tomography perfusion under low-dose conditions, measured using a hollow-fiber phantom.

The purpose of this study was to investigate the quantitative accuracy under low-dose conditions on computed tomography (CT) perfusion using a hollow-fiber phantom that had the theoretical absolute values of perfusion indices. Our phantom comprised two components, i.e., a hollow-fiber hemodialyzer to pump the diluted contrast material and a surrounding syringe-shaped X-ray-absorbing body to simulate the absorption of X-rays by a brain and cranium. We performed CTP scans on the phantom under various dose conditions ranging from 20 to 140mA using a 64-row CT scanner, measuring experimental cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) values using a deconvolution algorithm. The theoretical value of the CBV was within the 95% confidence interval of CBV values measured under 80mA. The CBV measured under low-dose settings and all CBF values measured were smaller than the theoretically calculated ones, and all MTT values measured were larger. All measured values of the CBV, CBF, MTT, and TTP decreased with an increase in image noise under lower dose conditions. It is difficult to define a low-dose limit in clinical scan conditions because of the complex characteristics of perfusion indices.

Impact of aberrant cerebral perfusion on resting-state functional MRI: A preliminary investigation of Moyamoya disease

The impact of chronic cerebral hypoperfusion on resting-state blood oxygen level-dependent signal fluctuations remains unknown. We aimed to determine whether chronic ischemia induces changes in amplitude of low-frequency fluctuations (ALFF) and to investigate the correlation between ALFF and perfusion-weighted magnetic resonance imaging (PWI) parameters in patients with moyamoya disease (MMD). Thirty patients with pre- and postoperative resting-state functional magnetic resonance imaging and PWI were included, and thirty normal controls underwent resting-state functional magnetic resonance imaging. A decrease in preoperative frontal lobe ALFF was observed in patients with MMD. Postoperative frontal lobe ALFF showed moderate improvement but still remained lower than those in normal controls. The values of mean transit time and time-to-peak, but not cerebral blood volume and cerebral blood flow, correlated significantly with frontal lobe ALFF. Moreover, there were significant negative correlations between changes in frontal lobe PWI parameters and changes in frontal lobe ALFF on both operated side and contralateral side after the unilateral revascularization surgery. Our results demonstrate that reduced ALFF are closely related to the abnormal PWI parameters and vary with the alteration of cerebral perfusion in patients with MMD.

Bedrock geology controls on catchment storage, mixing, and release: A comparative analysis of 16 nested catchments

AbstractThe bedrock controls on catchment mixing, storage, and release have been actively studied in recent years. However, it has been difficult to find neighbouring catchments with sufficiently different and clean expressions of geology to do comparative analysis. Here, we present new data for 16 nested catchments (0.45 to 410 km2) in the Alzette River basin (Luxembourg) that span a range of clean and mixed expressions of schists, phyllites, sandstones, and quartzites to quantify the relationships between bedrock permeability and metrics of water storage and release. We examined 9 years' worth of precipitation and discharge data, and 6 years of fortnightly stable isotope data in streamflow, to explore how bedrock permeability controls (a) streamflow regime metrics, (b) catchment storage, and (c) isotope response and catchment mean transit time (MTT). We used annual and winter precipitation–run‐off ratios, as well as average summer and winter precipitation–run‐off ratios to characterise the streamflow regime in our 16 study catchments. Catchment storage was then used as a metric for catchment comparison. Water mixing potential of 11 catchments was quantified via the standard deviation in streamflow δD (σδD) and the amplitude ratio (AS/AP) of annual cycles of δ18O in streamflow and precipitation. Catchment MTT values were estimated via both stable isotope signature damping and hydraulic turnover calculations. In our 16 nested catchments, the variance in ratios of summer versus winter average run‐off was best explained by bedrock permeability. Whereas active storage (defined here as a measure of the observed maximum interannual variability in catchment storage) ranged from 107 to 373 mm, total catchment storage (defined as the maximum catchment storage connected to the stream network) extended up to ~1700 mm (±200 mm). Catchment bedrock permeability was strongly correlated with mixing proxies of σδD in streamflow and δ18O AS/AP ratios. Catchment MTT values ranged from 0.5 to 2 years, based on stable isotope signature damping, and from 0.5 to 10 years, based on hydraulic turnover.

Study on CT perfusion surface permeability of cerebral hemorrhage in the basal ganglia region in subacute stage

Objective To investigate alterations of permeability of surface (PS) in subacute stage patients with intracerebral hemorrhage (ICH) using computed tomography perfusion imaging (CTPI), and analyze relationships between PS and other factors. Methods CTPI was performed in 35 patients in subacute stage (4 days-2 weeks) after onset of ICH, who were recruited in the Department of Neurology, the First Affiliated Hospital of Wenzhou Medical University from November 2015 to June 2016. Hematoma and edema volumes were measured, and perfusion parameters of perihematoma and mirror hemisphere side of marginal zone and outer zone of hematoma, including cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), PS, and relative value (ipsilateral/contralateral) of CBF (rCBF), CBV (rCBV), MTT (rMTT) and PS (rPS), were calculated. Relationships between volumes of hematoma and edema, time from onset to CTPI performance, NIHSS scores and PS of perihematoma zone were analyzed by Pearson correlation analysis. Results The perihematoma PS ((1.87±0.48) ml·100 g-1·min-1) was higher than that in contralateral regions ((1.28±0.34) ml·100 g-1·min-1;t=-12.407, P 0.05). There were 20 patients with hematoma volume less than 10 ml and 15 patients with hematoma volume more than 10 ml, while the mean value of perihematoma PS of them showed no statistically significant difference (P>0.05). And there were no statistically significant correlations between perihematoma PS and NIHSS scores at the time of admission, CTPI examination and discharge (all P>0.05). Conclusions In subacute stage of ICH, the blood brain barrier permeability of perihematoma area is still abnormal, manifested as PS increases. The perihematoma PS positively correlates with the time of ICH onset. CTPI can accurately reflect this change, and potentially provide valuable information for evaluation and individual treatment of patients. Key words: Intracerebral hemorrhage; Tomography, X-ray computed; Perfusion; Capillary permeability; Subacute stage

Analysis of arterial dynamic micro-vascularization with contrast-enhanced ultrasound (CEUS) inthyroid lesions using external perfusionsoftware: First results.

To determine different perfusion characteristics of histo-pathologically proven adenomas and carcinomas of the thyroid gland with CEUS and perfusion software. Retrospective perfusion analysis of 25 patients with carcinomas and 41 cases of adenomas of the thyroid gland (30 males, 36 females; aged 18 - 85 years, mean 56 years). All cases were histologically analyzed. Perfusion analysis was independently performed using external perfusion software (VueBox®). TTP, mTT, Peak and Rise time were calculated. Lesions' sizes ranged from 0.2 to 10.2 cm in carcinomas (mean 2.18 cm), and from 0.6 to 5.0 cm in adenomas (mean 2.25 cm). In 20 out of 25 carcinomas that were evaluated with CEUS, a complete wash-out in the late venous phase was found. Adenomas showed wash-out at the border.Perfusion analysis in VueBox® revealed some parameters which tend to show differences between adenomas and carcinomas, however did not reach the level of significance.Median Peak in carcinomas was highest at the margins (2945 rU), and lowest in the surroundings (1110 rU). Mean Transit Time (mTT) values showed no differences between center, margin and surrounding.In adenomas healthy tissue showed higher mTT values compared to the center (24.6 vs. 20.7 sec). Median Peak was highest in the surrounding tissue and lowest in the margins (1999 vs. 1129 rU). No statistical differences could be found in the comparisons. CEUS with perfusion analysis offers new possibilities for the dynamic evaluation of micro-vascularization in thyroid adenomas and carcinomas. Using VueBox® the perfusion analysis of the arterial phase provides new parameters that help determine a lesion's malignancy or benignity. However a final assessment regarding malignancy and benignity of thyroid lesions using only CEUS and perfusion analysis of the arterial phase is not yet possible.

Large decompressive craniectomy combined with vascular reconstruction in patients with severe craniocerebral injury

Aim: This study aims to compare the effect of large decompressive craniectomy combined with vascular reconstruction and traditional decompressive craniectomy in the treatment of severe craniocerebral injury. Methods: Forty-eight cases of severe craniocerebral injury were collected from March 2012 to March 2015 in Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology. Patients undergoing large decompressive craniectomy combined with vascular reconstruction or traditional decompressive craniectomy were randomly divided into two groups: the experimental group and the control group. The hemodynamic changes were observed by computed tomography perfusion, and the postoperative Glasgow Outcome Score (GOS) was analyzed. Results: The cerebral blood flow (CBF) and cerebral blood volume (CBV) scores in experimental group were higher than that in the control group at 1 week and 1 month after the operation (P < 0.05). The mean transit time (MTT) and time to peak (TTP) scores in experimental group were lower than that in the control group at 1 week and 1 month after the operation (P < 0.05). The relative CBF and relative CBV values of the control group in 1 week were higher than that in 1 month, while the relative MTT and relative TTP values in 1 week were lower than that in 1 month. The rate of good recovery (including good and residual cases) in experimental group was higher than that in the control group whereas the rate of poor recovery (including severe disability, vegetative state, and death) in experimental group was lower than that in the control group (P < 0.05). Conclusion: The large decompressive craniectomy combined with vascular reconstruction can not only decrease intracranial pressure but also recover the blood supply of the brain. It deserves the clinical promotion.

Effect of CYP2D6 polymorphisms on the pharmacokinetics of propafenone and its two main metabolites

Propafenone (PPF) is an antiarrhythmic drug, metabolized mainly by CYP2D6 to 5-hydroxypropafenone (5OH-PPF) and by CYP3A4 to norpropafenone (NOR-PPF). CYP2D6 shows a high degree of genetic polymorphism which is associated with diminished antiarrhythmic efficacy or cardiac seizures/cardiotoxicity. This study aimed to investigate the effect of the CYP2D6 polymorphism on the pharmacokinetics of PPF and its two main metabolites. The usefulness of PPF/5OH-PPF ratio for CYP2D6 phenotyping in healthy adults was also evaluated. Twelve healthy volunteers, 3 poor metabolizers (PM), 2 intermediate metabolizers (IM) and seven extensive metabolizers (EM) received an oral dose of PPF. Concentrations of PPF and its metabolites were analyzed in serum samples over 27h. The PPF/5OH-PPF ratio distinguished EMs from PMs, but not from IMs. In PMs, the mean transit time (MTT) values were almost the same for PPF and NOR-PPF and much higher than those of EMs and IMs. 5OH-PPF was not detected in EMs. Mean MTT values of 5OH-PPF and NOR-PPF in IMs were 5.27- and 1.52-fold higher than those of EMs. A single time point serum PPF-MR approach is a useful tool to identify PMs. CYP2D6 polymorphism significantly affects the pharmacokinetics of PPF and its two metabolites.

Contrast-enhanced transrectal ultrasound for prediction of prostate cancer aggressiveness: The role of normal peripheral zone time-intensity curves.

To assess the role of time-intensity curves (TICs) of the normal peripheral zone (PZ) in the identification of biopsy-proven prostate nodules using contrast-enhanced transrectal ultrasound (CETRUS). This study included 132 patients with 134 prostate PZ nodules. Arrival time (AT), peak intensity (PI), mean transit time (MTT), area under the curve (AUC), time from peak to one half (TPH), wash in slope (WIS) and time to peak (TTP) were analyzed using multivariate linear logistic regression and receiver operating characteristic (ROC) curves to assess whether combining nodule TICs with normal PZ TICs improved the prediction of prostate cancer (PCa) aggressiveness. The PI, AUC (p < 0.001 for both), MTT and TPH (p = 0.011 and 0.040 respectively) values of the malignant nodules were significantly higher than those of the benign nodules. Incorporating the PI and AUC values (both, p < 0.001) of the normal PZ TIC, but not the MTT and TPH values (p = 0.076 and 0.159 respectively), significantly improved the AUC for prediction of malignancy (PI: 0.784–0.923; AUC: 0.758–0.891) and assessment of cancer aggressiveness (p < 0.001). Thus, all these findings indicate that incorporating normal PZ TICs with nodule TICs in CETRUS readings can improve the diagnostic accuracy for PCa and cancer aggressiveness assessment.

Preliminary study on assessment of lexiscan-induced blood-brain barrier opening and its level by CT perfusion imaging

Objective: To evaluate the level of lexiscan-induced blood-brain barrier opening of healthy rabbits via CT perfusion weighted imaging (PWI) scan. Methods: Between November 2014 and May 2015, thirty New Zealand white rabbits were randomly assigned into three groups: the experimental group A1 which received one injection of lexiscan(1 ml/kg); the experimental group A2 which received three times injection of lexiscan(total dose: 1.5 ml/kg), finished within 15 minutes; the control group B which was injected the same volume normal saline(1 ml/kg), after 30 minutes, CT PWI scan was performed. Then cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and permeability surface(PS) of the region of interest of each group were acquired and compared statistically. Five cases of each group were injected with 2% Evans blue intravenously posterior to imaging. After one hour of infusion, all the animals were killed. Their brains were examined for the determination of Evans blue distribution. Results: Both the values of CBF and CBV and the staining with Evans blue of the group A1(CBF: (89.88±2.21), (81.42±4.28) ml·(100 g)-1·min-1; CBV: (3.97±0.43), (3.66±0.16) ml/g)and group A2 (CBF: (75.16±0.84), (63.66±7.21) ml·(100 g)-1·min-1; CBV: (4.07±0.01), (3.75±0.05) ml/g) were higher than those of the group B(CBF: (20.08±5.08), (14.58±8.62) ml·(100 g)-1·min-1; CBV: (0.85±0.04), (0.65±0.17) ml/g), the differences were all statistically significant (all P<0.01). While there was no statistically difference between group A1 and group A2(P>0.05). The value of PS of the group A2((22.43±8.09), (20.20±7.01)ml·(100 g)-1·min-1 )was higher than that of group A1((13.82±4.44), (10.12±2.44)ml·(100 g)-1·min-1) and group B(0.00, 0.00)(the lowest one), the differences were all statistically significant(all P<0.01). The value of MTT of the group A1((2.50±0.82, 2.47±0.10) s) had no statistical difference with group A2 and group B, while the value of group A2((4.50±0.17), (4.72±0.15) s) was higher than that of group B((1.88±0.09), (1.99±0.00) s), the differences were all statistically significant (P<0.05). Conclusion: Changes in hemodynamics of lexiscan-induced blood-brain barrier opening can be monitored by CT PWI scan. When the total dose of lexiscan increasing, the level of the BBB opening is higher with significantly increased CBF, CBV, PS and MTT.

Perfusion computed tomography: 4 cm versus 8 cm coverage size in subjects with chronic carotid artery stenosis.

The impact of coverage size on global cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP) parameters has not been investigated in patients with chronic carotid artery stenosis. 63 patients with stenosis of >70% within a single internal carotid artery and neurological symptoms were randomly assigned to two well-matched groups. Differences in CT perfusion scan over a 4 cm or 8 cm range of the brain were compared between the two groups. The CBF and CBV values were higher in the 4 cm coverage size than in the 8 cm coverage size (by 14.7 and 10.7% on the ipsilateral side and 17.2 and 7.8% on the contralateral side, respectively; all p < 0.001). The MTT value was higher in the 4 cm coverage size than in the 8 cm coverage size on the ipsilateral side (9.6%; p < 0.001). There was no difference between MTT values in the contralateral size. There were no differences between TTP values on the ipsilateral and contralateral sides. The relative indices rMTT and rTTP were higher in the 4 cm coverage size than in the 8 cm coverage size (8.2%, p < 0.001, and 1.1%, p < 0.005, respectively). Absolute CBF and CBV values and relative rMTT and rTTP indices in patients with low CBF and low CBV are highly dependent on coverage size. We recommend using a 4 cm coverage size to assess global cerebral perfusion parameters owing to better accuracy and quicker post-processing. To the best of our knowledge, this is the first article to compare the influence of 4 cm vs 8 cm coverage size on cerebral perfusion parameters such as CBF, CBV, MTT and TTP in subjects with chronic carotid artery stenosis.

Indicative mean transit time estimation from δ18O values as groundwater vulnerability indicator in karst-fissure aquifers

Ideally, groundwater vulnerability assessment should take into account potential contaminant breakthrough curve, characterized by transit time, relative change of contamination concentration (input/output) and duration of overstepped concentration. Still, a majority of groundwater vulnerability assessment methods that tend to be more physically based count only with the value of mean transit time (MTT), the elapsed time when groundwater can exit the aquifer after its recharge. In this paper, indicative values of MTT derived from single δ18O sampling values were used to estimate intrinsic vulnerability of individual springs occurring on the Muranska planina Plateau (Slovakia). For 295 springs sampled within 10 days, δ18O was found in the range between −10.90 and −7.32 ‰, without signs of altitudinal effect. According to International Atomic Energy Agency (IAEA) Global Network of Isotopes in Precipitation (GNIP) stations, significant contrast in precipitation δ18O values was found several weeks before sampling. Indicative MTT value, e maxMTT (estimated longest possible mean transit time), was calculated from sine wave course of monitored precipitation isotopic composition, δ18O value in the spring groundwater sample and altitudes of sampled point and precipitation station. Estimated e maxMTT values suggest that heavier oxygen isotopes in samples probably reflect quick circulation and a more vulnerable environment as influenced by enriched summer precipitation. Depleted δ18O suggests lower vulnerability represented by higher e maxMTT values.