Differences In Perfusion Parameters Research Articles

A Novel Self-Supervised Learning-Based Method for Dynamic CT Brain Perfusion Imaging.

Dynamic computed tomography (CT)-based brain perfusion imaging is a non-invasive technique that can provide quantitative measurements of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). However, due to high radiation dose, dynamic CT scan with a low tube voltage and current protocol is commonly used. Because of this reason, the increased noise degrades the quality and reliability of perfusion maps. In this study, we aim to propose and investigate the feasibility of utilizing a convolutional neural network and a bi-directional long short-term memory model with an attention mechanism to self-supervisedly yield the impulse residue function (IRF) from dynamic CT images. Then, the predicted IRF can be used to compute the perfusion parameters. We evaluated the performance of the proposed method using both simulated and real brain perfusion data and compared the results with those obtained from two existing methods: singular value decomposition and tensor total-variation. The simulation results showed that the overall performance of parameter estimation obtained from the proposed method was superior to that obtained from the other two methods. The experimental results showed that the perfusion maps calculated from the three studied methods were visually similar, but small and significant differences in perfusion parameters between the proposed method and the other two methods were found. We also observed that there were several low-CBF and low-CBV lesions (i.e., suspected infarct core) found by all comparing methods, but only the proposed method revealed longer MTT. The proposed method has the potential to self-supervisedly yield reliable perfusion maps from dynamic CT images.

Evaluation of utero-placental vascularization using contrast-enhanced ultrasound: Early first trimester maternal perfusion of the intervillous space is confirmed

IntroductionThe objective was to confirm and semiquantify the maternal perfusion of the intervillous space between 8 and 13 + 6 gestational weeks (GW). MethodsWe conducted a prospective, multicenter, and nonrandomized open study. Women undergoing voluntary termination of pregnancy at three different gestational ages (Group 8 GW: 8 to 8 + 6 GW, Group 11GW: 11 to 11 + 6 GW and Group 13GW: 13 to 13 + 6 GW) were included, with 14 subjects per group. Women presenting with a personal risk of preeclampsia and/or intrauterine growth restriction were excluded. Contrast-enhanced ultrasound (CEUS) was performed with an intravenous bolus administration of 2.4 mL of microbubbles. The region of interest (ROI) was the entire placenta. The perfusion curves and kinetic parameters, including wash-in perfusion index, peak enhancement and mean transit time, were calculated. ResultsOf the 42 women initially included, interpretable perfusion curves could be obtained for 33. Regardless of the gestational age, contrast was observed in the entire placenta. No significant difference in perfusion parameters was observed between groups. There was an association between signal intensity and both maternal heart frequency and placental location. Signal intensity was decreased when the heart frequency increased (p < 0.05) and when the placenta was in a nonanterior position (p > 0.005). DiscussionWe confirmed the presence of maternal perfusion of the intervillous space as early as 8 GW. No significant increase in perfusion parameters was observed between 8 and 13 + 6 GW. Our observations, in accordance with the previous experiment published by Roberts et al.1, strongly challenge the classic trophoblastic plug theory.

Prediction of post transarterial chemoembolization MR images of hepatocellular carcinoma using spatio-temporal graph convolutional networks.

Magnetic resonance imaging (MRI) plays a critical role in the planning and monitoring of hepatocellular carcinomas (HCC) treated with locoregional therapies, in order to assess disease progression or recurrence. Dynamic contrast-enhanced (DCE)-MRI sequences offer temporal data on tumor enhancement characteristics which has strong prognostic value. Yet, predicting follow-up DCE-MR images from which tumor enhancement and viability can be measured, before treatment of HCC actually begins, remains an unsolved problem given the complexity of spatial and temporal information. We propose an approach to predict future DCE-MRI examinations following transarterial chemoembolization (TACE) by learning the spatio-temporal features related to HCC response from pre-TACE images. A novel Spatial-Temporal Discriminant Graph Neural Network (STDGNN) based on graph convolutional networks is presented. First, embeddings of viable, equivocal and non-viable HCCs are separated within a joint low-dimensional latent space, which is created using a discriminant neural network representing tumor-specific features. Spatial tumoral features from independent MRI volumes are then extracted with a structural branch, while dynamic features are extracted from the multi-phase sequence with a separate temporal branch. The model extracts spatio-temporal features by a joint minimization of the network branches. At testing, a pre-TACE diagnostic DCE-MRI is embedded on the discriminant spatio-temporal latent space, which is then translated to the follow-up domain space, thus allowing to predict the post-TACE DCE-MRI describing HCC treatment response. A dataset of 366 HCC's from liver cancer patients was used to train and test the model using DCE-MRI examinations with associated pathological outcomes, with the spatio-temporal framework yielding 93.5% classification accuracy in response identification, and generating follow-up images yielding insignificant differences in perfusion parameters compared to ground-truth post-TACE examinations.

Histogram analysis of arterial spin labeling perfusion data to determine the human papillomavirus status of oropharyngeal squamous cell carcinomas.

To evaluate the correlation between histogram parameters derived from pseudo-continuous arterial spin labeling (PCASL) and human papillomavirus (HPV) status in patients with oropharyngeal squamous cell carcinoma (OPSCC). This study included a total of 58 patients (HPV-positive: n = 45; -negative: n = 13) from a prospective cohort of consecutive patients aged ≥ 18years, who were newly diagnosed with oropharyngeal squamous cell carcinoma. All patients were required to have undergone pre-treatment MRI with PCASL to measure regional perfusion. The region of interest was drawn by two radiologists, encompassing the entire tumor volume on all corresponding slices. Differences in the histogram parameters derived from tumor blood flow (TBF) in ASL were assessed for HPV-positive and -negative patients. Receiver operating characteristic curve analysis was performed to determine the best differentiating parameters, and a leave-one-out cross-validation was used. Patients with HPV-positive OPSCC showed a significantly lower overall standard deviation and 95th percentile value of tumor blood flow (P < .007). The standard deviation of TBF was the single best predictive parameter. Leave-one-out cross-validation tests revealed that the area under the receiver operating characteristic curve, accuracy, sensitivity, and specificity were 0.745, 75.9%, 75.6%, and 76.9%, respectively. PCASL revealed differences in perfusion parameters according to HPV status in patients with OPSCC, reflecting their distinct histopathology.

Combined treatment of sorafenib and doxorubicin-loaded microbubble-albumin nanoparticle complex for hepatocellular carcinoma: A feasibility study.

PurposeTo assess the feasibility of the combined sorafenib (SOR) and doxorubicin-loaded microbubble-albumin nanoparticle complex (DOX-MAC) treatment effect in an orthotopic rat model of hepatocellular carcinoma (HCC).Materials and methodsSixty-two rats with N1-S1 hepatoma were divided into four groups according to the treatment methods, i.e. G1 (SOR and DOX-MAC; n = 12), G2 (SOR; n = 15), G3 (DOX-MAC; n = 12), G4 (DOX; n = 11), and G5 (normal saline; n = 12). We performed the theragnostic, contrast-enhanced ultrasound examination and treatment at the baseline, one-week, and two-weeks. Tumor volume and perfusion parameters were compared at each time point and the differences between all of the groups over time were analyzed using repeated measures ANOVA. We also analyzed the apoptotic index and microvessel density (MVD) per each tumor specimen in all of the groups.ResultsThe tumors increased from the beginning in all of the groups to the final follow-up, whereas the tumor growth in the G1 group and the G2 group was inhibited during the treatment period compared to the baseline tumor volume (P = 0.016 and P = 0.031). The G1 group resulted in tumor growth inhibition compared to the control group (P = 0.008). The G1 group showed that the peak enhancement and wash-in area under the curve were lower than that of the G4 group (P = 0.010 and 0.022). However, there was no difference in perfusion parameters in the other treated group compared to control group. The MVD of the G1 group tumor was lower than that of the G4 group (P = .016).ConclusionOur results suggest that the combination therapy of SOR and DOX-MAC can cause inhibition of tumor growth after treatment and that this therapy can be adequately monitored using the theragnostic DOX-MAC agent.

CTNI-14. A 3-ARM, PHASE IIA TRIAL OF SAFETY &amp; EFFICACY OF OLINVACIMAB, A MONOCLONAL ANTIBODY TO VEGFR2 IN PATIENTS WITH RECURRENT GLIOBLASTOMA MULTIFORME WITH IMAGING AND PK/PD ASSESSMENTS: FINAL REPORT

Abstract The VEGF pathway remains an important target in GBM given its vascularity and autocrine VEGF signalling. Olinvacimab (TTAC-0001) is a fully humanised VEGFR2 Mab that binds and inhibits the receptor. This report assesses the safety, dosing schedules and efficacy of Olinvacimab in recurrent GBM. We conducted a two-site, 3 arm, open-label study of Olinvacimab in recurrent GBM. Eligible patients were ≥18 years with RANO-measurable lesion, KPS ≥ 80, and had completed chemoradiotherapy without prior bevacizumab therapy. We assessed three arms, 8 mg/kg and 12mg/kg weekly for 3 of every 4 weeks, and 12 mg/kg weekly. Three patients were treated in arms 1 and 2 and 6 in arm 3. Safety assessments were performed prior to dose escalation. The main toxicity was development of grade 1 (67%) and 2 (8%%) cutaneous haemangiomas. Common toxicities seen with other VEGF directed therapies, including hypertension, impaired wound healing, and proteinuria were not seen in this cohort. Efficacy was assessed by MRI using RANO criteria. 6 month PFS was 17%, with disease control in 25%, with steroid dose reduction. The longest response was 15 months. On DCE MRI, there was no significant difference in perfusion parameters between baseline and 1st follow-up MRI comparing those with SD and PD. However, 6 of 12 patients showed decreased Ktrans &amp;gt; 20 % of baseline, consistent with an anti-angiogenic effect of Olinvacimab. Pharmacokinetics showed a decreased clearance rate and increased half-life of Olinvacimab compared to the prior Phase I study. Pharmacodynamic studies showed significantly higher levels of angiogenic markers, particularly VEGF-A in those treated at 12mg/kg vs arm 1. VEGF-A, C and D levels were elevated in patients with SD compared to those with PD. Conclusion: Olinvacimab was well tolerated with a different toxicity profile to other VEGFR directed therapies. There were promising responses in 25% of patients.

Magnetic resonance enterography perfusion parameters reveal complex changes in affected and unaffected segments in Crohn’s disease

Objectives To compare dynamic contrast-enhanced (DCE)-MRI parameters in affected and unaffected segments of CD patients with those of a control group, and to assess the correlation between DCE-MRI parameters and clinical index of activity (HBI) as well as biomarkers (CRP and faecal calprotectin). Methods We performed a single-center prospective study of CD patients and control subjects who underwent DCE-MRI. Regions of interest were drawn in segments and the program (Olea Medical – Canon) provided values for transfer constant (Ktrans), fractional volume of extravascular-extracellular space (Ve), slope of enhancement (SoE), time to maximum enhancement (TME), maximum enhancement (ME) and enhancement ratio (ER) which were determined and compared. Results Fifteen CD patients (mean age 42 years; 10 women) and 7 healthy subjects (mean age 40.4 years; 6 women) were included. Paired comparisons of affected and unaffected segments in CD showed a significant increase of all parameters in affected segments, except for ER and TME. When comparing to controls, the affected segments did not show any significant difference, while a significant decrease in most of the parameters (except for ER and TME) was observed when comparing unaffected segments of CD patients to controls. In CD, significant correlations between DCE-MRI parameters and biomarkers (CRP, faecal calprotectin) were more frequent in unaffected segments than in affected segments. Conclusions Significant differences in perfusion parameters were observed between affected and unaffected segments of CD patients and between unaffected segments and those of control subjects. This suggests complex perfusion changes in both unaffected and affected intestinal segments in CD.

Role of dynamic perfusion magnetic resonance imaging in patients with local advanced rectal cancer.

BACKGROUNDThe management of rectal cancer patients is mainly based on the use of the magnetic resonance imaging (MRI) technique as a diagnostic tool for both staging and restaging. After treatment, to date, the evaluation of complete response is based on the histopathology assessment by using different tumor regression grade (TRG) features (e.g., Dworak or Mandard classifications). While from the radiological point of view, the main attention for the prediction of a complete response after chemotherapy treatment focuses on MRI and the potential role of diffusion-weighted images and perfusion imaging represented by dynamic-contrast enhanced MRI. The main aim is to find a reliable tool to predict tumor response in comparison to histopathologic findings.AIMTo investigate the value of dynamic contrast-enhanced perfusion-MRI parameters in the evaluation of the healthy rectal wall and tumor response to chemo-radiation therapy in patients with local advanced rectal cancer with histopathologic correlation.METHODSTwenty-eight patients with biopsy-proven rectal adenocarcinoma who underwent a dynamic contrast-enhanced MR study performed on a 1.5T MRI system (Achieva, Philips), before (MR1) and after chemoradiation therapy (MR2), were enrolled in this study. The protocol included T1 gadolinium enhanced THRIVE sequences acquired on axial planes. A dedicated workstation was used to generate color permeability maps. Region of interest was manually drawn on tumor tissue and normal rectal wall, hence the following parameters were calculated and statistically analyzed: Relative arterial enhancement (RAE), relative venous enhancement (RVE), relative late enhancement (RLE), maximum enhancement (ME), time to peak and area under the curve (AUC). Perfusion parameters were related to pathologic TRG (Mandard's criteria; TRG1 = complete regression, TRG5 = no regression).RESULTSTen tumors (36%) showed complete or subtotal regression (TRG1-2) at histology and classified as responders; 18 tumors (64%) were classified as non-responders (TRG3-5). Perfusion MRI parameters were significantly higher in the tumor tissue than in the healthy tissue in MR1 (P < 0.05). At baseline (MR1), no significant difference in perfusion parameters was found between responders and non-responders. After chemo-radiation therapy, at MR2, responders showed significantly (P < 0.05) lower perfusion values [RAE (%) 54 ± 20; RVE (%) 73 ± 24; RLE (%): 82 ± 29; ME (%): 904 ± 429] compared to non-responders [RAE (%): 129 ± 45; RVE (%): 154 ± 39; RLE (%): 164 ± 35; ME (%): 1714 ± 427]. Moreover, in responders group perfusion values decreased significantly at MR2 [RAE (%): 54 ± 20; RVE (%): 73 ± 24; RLE (%): 82 ± 29; ME (%): 904 ± 429] compared to the corresponding perfusion values at MR1 [RAE (%): 115 ± 21; RVE (%): 119 ± 21; RLE (%): 111 ± 74; ME (%): 1060 ± 325]; (P < 0.05). Concerning the time-intensity curves, the AUC at MR2 showed significant difference (P = 0.03) between responders and non-responders [AUC (mm2 × 10-3) 121 ± 50 vs 258 ± 86], with lower AUC values of the tumor tissue in responders compared to non-responders. In non-responders, there were no significant differences between perfusion values at MR1 and MR2.CONCLUSIONDynamic contrast perfusion-MRI analysis represents a complementary diagnostic tool for identifying vascularity characteristics of tumor tissue in local advanced rectal cancer, useful in the assessment of treatment response.

Difference in Perfusion Parameters Between Gastric Cancer and Gastric Stromal Tumors: Evaluation With Oral Contrast Plus Contrast-Enhanced Ultrasonography.

Objective: To explore the difference of perfusion parameters between gastric cancer (GC) and gastric stromal tumors (GSTs) by using oral contrast plus contrast-enhanced ultrasonography (OC+CEUS).Methods: We retrospectively reviewed 149 patients with histologically confirmed gastric lesions (80 patients with GC and 69 patients with GST). OC+CEUS was performed in all patients in the GC group and the GST group before surgery. The cine loops of OC+CEUS of all cases were analyzed. The perfusion parameters including arrival time (AT), time to peak (TTP), basal intensity (BI), and peak intensity (PI) were obtained via a program designed for autotracking contrast quantification (ACQ). The between-group differences in these parameters were compared.Results: According to time-intensity curve (TIC) analysis, high-risk GST had higher PI than low-risk GST (P < 0.05). GC had faster AT and higher PI than normal gastric wall (P < 0.05); GST had higher PI than normal gastric wall (P < 0.05). Furthermore, the GC group had faster AT and higher PI than the GST group (P < 0.05). In contrast, the difference in BI and peak time (TTP) between the groups was not significant (P > 0.05).Conclusion: AT and PI differ significantly between the GC group and the GST group. As a new method, OC+CEUS has value for the differential diagnosis of GC and GST.

The Value of Whole-Brain Perfusion Parameters Combined with Multiphase Computed Tomography Angiography in Predicting Hemorrhagic Transformation in Ischemic Stroke

Objective: To explore the value of whole-brain perfusion parameters combined with multiphase computed tomography angiography (MP-CTA) in predicting the hemorrhagic transformation (HT) of ischemic stroke. Methods: A total of 64 patients with ischemic stroke who underwent noncontrast computed tomography, computed tomography perfusion imaging, and computed tomography angiography before treatment from August 2017 to June 2019 were included retrospectively. The perfusion parameters cerebral blood volume (CBV), cerebral blood flow (CBF), time to peak (TTP), mean transit time (MTT), time to maximum (Tmax), and permeability surface (PS) were measured by postprocessing software (Advantage Workstation 4.7 (Revolution, GE Healthcare, USA)), and their ratios between the healthy and affect side relative CBV, relative CBF, relative time to peak (rTTP), relative mean transit time (rMTT), relative Tmax, and relative permeability surface (rPS) were calculated. The differences in perfusion parameters between the HT group and the non-HT group were evaluated. The collateral circulation scores and HT rates were assessed by MP-CTA. Receiver operating characteristic curves were drawn to analyze the diagnostic efficiency of valuable parameters and their correlations with HT. The rate of HT in different treatments were compared. Results: The CBV values in the HT group were lower than those in the non-HT group (P < .05), while the TTP, MTT, Tmax, PS, rTTP, rMTT, and rPS values in the HT group were higher than those in the non-HT group (P < .05). PS (r = .63, area under curve = .881) and rPS (r = .52, area under curve = .814) were significantly correlated with HT. The combination of perfusion parameters and the MP-CTA scores can improve the diagnostic efficiency (area under curve = .891). The HT rate in the group with poor collateral (64.29%) was higher than that in the group with good collateral (11.11%). Conclusions: Whole-brain perfusion parameters and MP-CTA scores have important application value in assessing the HT risk of ischemic stroke patients before treatment.

Evaluation of total liver perfusion imaging of CT for efficacy of transcatheter arterial chemoembolization combined with apatinib on rabbit VX2 liver tumors

To investigate the value of the total liver CT perfusion imaging in the evaluation of rabbit VX2 liver tumors treated with TACE and apatinib. Methods: Thirty-six rabbit VX2 liver cancer models were established and randomly divided into 4 groups. Group A: simple TACE group; Group B: simple oral administration of apatinib mesylate; Group C: TACE + oral apatinib mesylate; Group D: control group, administration of saline. CT perfusion imaging (CTPI) was performed before treatment and on the 7 and 14 days after the treatment to acquire perfusion parameters including blood flow (BF), blood volume (BV), MTT (mean transit time), surface permeability (PS), and hepatic artery fraction (HAF). One tumor rabbit was sacrificed in each group after the first perfusion scan, and the remaining tumor rabbits were sacrificed after the last perfusion scan on the 14th day of the treatment. The borders of the tumors were stained immunohistochemically, and microvascular density (MVD) was measured by anti-CD34. The differences of perfusion parameters were compared to evaluate the liver hemodynamic changes, and statistical repeated measurement variance analysist correlation analysis were performed. Results: There were no significant differences in CTPI parameters of BF, BV, MTT, HAF and PS between the 4 groups before treatment (P>0.05). After the treatment, HB, HAF and PS were decreased significantly in Group A, B, and C and slightly increased in the Group D. The value of MVD after 14 d treatment was 80.1±16.4 in Group A, 50.2±11.2 in Group B, 27.4±9.7 in Group C, 68.7±12.7 in Group D, respectively. The value of MVD in the Group C were significantly lower than that in Group A, B, and D. It showed positive correlation between BF, HAF, PS and MVD in Group B, C, and D, and there was no significant correlation between BV, MTT and MVD. It showed no significant correlation between MVD and each CTPI parameter in Group A. Conclusion: Total liver CT perfusion can quantitatively evaluate the blood perfusion information of rabbit liver VX2 tumor after TACE. TACE combined with oral apatinib can effectively inhibit tumor growth and improve the therapeutic effect of VX2 tumor.

MpMRI of the prostate: is there a role for semi-quantitative analysis of DCE-MRI and late gadolinium enhancement in the characterisation of prostate cancer?

To assess whether there is a significant difference in perfusion parameters between benign and malignant prostatic lesions, focusing on semi-quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and presence of late gadolinium enhancement (LGE). Three hundred and thirteen patients who underwent multiparametric MRI (mpMRI) of the prostate and with available corresponding histology (prostatectomy or biopsy) were selected retrospectively for this study. The MRI protocol consisted of multiplanar T2-and diffusion-weighted imaging, DCE and delayed axial T1 images. Images were reviewed independently by two radiologists for LGE assessment and Prostate Imaging - Reporting and Data System (PI-RADS) scoring. For each lesion, semi-quantitative analysis of DCE-MRI was performed and the following data were evaluated: time to peak, wash-in rate, wash-out rate, brevity of enhancement, and area under the curve. The presence or absence of LGE in delayed axial T1 images was assessed qualitatively. MRI results were compared to histology. The presence of significant prostate cancer was based both on Epstein criteria (SPC) and Gleason score (GS ≥7). SPC and Gleason score ≥7 tumours showed significant lower time to peak and brevity of enhancement (p<0.001) with higher wash-in rate (p=0.001). LGE was observed in 152/313 (49%) cases; among them 103/152 (68%) did not show SPC whereas 49/152 (32%) had SPC (p<0.001). The presence of LGE determined a risk reduction of SPC resulting as an independent predictor at multivariate analysis (logOR=-0.78, SE 0.33, p=0.02). Semi-quantitative perfusion analysis and LGE may help to predict the presence/absence of a significant prostate tumour and represent a promising tool to improve mpMRI diagnostic performance.

Commentary on: mpMRI of the prostate: is there a role for semi-quantitative analysis of DCE-MRI and late gadolinium enhancement in the characterisation of prostate cancer?

Aim To assess whether there is a significant difference in perfusion parameters between benign and malignant prostatic lesions, focusing on semi-quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and presence of late gadolinium enhancement (LGE). Material and methods Three hundred and thirteen patients who underwent multiparametric MRI (mpMRI) of the prostate and with available corresponding histology (prostatectomy or biopsy) were selected retrospectively for this study. The MRI protocol consisted of multiplanar T2-and diffusion-weighted imaging, DCE and delayed axial T1 images. Images were reviewed independently by two radiologists for LGE assessment and Prostate Imaging – Reporting and Data System (PI-RADS) scoring. For each lesion, semi-quantitative analysis of DCE-MRI was performed and the following data were evaluated: time to peak, wash-in rate, wash-out rate, brevity of enhancement, and area under the curve. The presence or absence of LGE in delayed axial T1 images was assessed qualitatively. MRI results were compared to histology. The presence of significant prostate cancer was based both on Epstein criteria (SPC) and Gleason score (GS ≥7). Results SPC and Gleason score ≥7 tumours showed significant lower time to peak and brevity of enhancement (p Conclusion Semi-quantitative perfusion analysis and LGE may help to predict the presence/absence of a significant prostate tumour and represent a promising tool to improve mpMRI diagnostic performance.

Myocardial perfusion assessed with cardiac computed tomography in women without coronary heart disease

Combined coronary CT angiography and CT perfusion (CTP) is a novel, non-invasive, 'one-stop' diagnostic tool to rule out ischaemia in patients suspected for coronary artery disease (CAD). However, the normal myocardial perfusion pattern by static CTP in humans is poorly described. We aimed to investigate global and regional myocardial perfusion during rest and adenosine-induced hyperaemia in asymptomatic women without history of coronary heart disease (CHD). Using a 320-row CT scanner with a static protocol, semi-quantitative assessment of rest and stress CTP was performed in 34 asymptomatic middle-aged women without obstructive CAD (<50% stenosis) or history of CHD, and with normal exercise stress test and left ventricular (LV) function. Using a 16-segment model, we assessed global and regional values of LV myocardial perfusion reserve (MPR) and transmural perfusion ratio (TPR). Mean±SD age was 56±13years. Resting and hyperaemic myocardial perfusion was heterogeneously distributed throughout the LV myocardium. During hyperaemia, global MPR increased by median (IQR) 158% (144-176) with the highest increase in the right coronary artery territory (171%; P<0.02). Rest and stress segmental TPR values ranged between 0.93-1.26 and 0.99-1.13, respectively, with the lowest values detected in the inferoseptal segments. No differences in perfusion parameters were found between participants with normal epicardial arteries and participants with non-significant epicardial atheromatosis (all P>0.05). Global perfusion parameters were not associated with age or menopausal status (all P>0.05). This descriptive study presents data on global and regional myocardial perfusion in a cohort of healthy middle-aged women.

Assessment of Myocardial Perfusion at Rest and During Stress Using Dynamic First-Pass Contrast-Enhanced Magnetic Resonance Imaging in Healthy Dogs.

Objective: To assess the feasibility of myocardial perfusion analysis in healthy dogs using dynamic contrast-enhanced cardiac magnetic resonance (DCE-MR) imaging at rest and during simulated stress with two doses of adenosine.Animals: Ten healthy beagle dogs.Procedures: Dogs were anesthetized and positioned in dorsal recumbency in a 3.0 Tesla MR scanner. Electrocardiogram-triggered dynamic T1-weighted ultrafast gradient echo images of three slices in short-axis orientation of the heart were acquired during breath holds and the first pass of gadolinium contrast. Image acquisition was performed after 4 min infusion of 140 μg/kg/min and 280 μg/kg/min adenosine and, after a washout period, without adenosine, respectively. Images were processed by dividing each slice into 6 radial segments and perfusion analysis was performed from signal intensity-time data.Results: No differences in perfusion parameters were found between segments within any of the slices, but significant differences were found between slices for peak enhancement, accumulated enhancement, and the maximum upslope. In addition, significant differences were found within each slice between data at rest and during adenosine-induced stress for the relative and absolute maximum upslope, relative peak enhancement, time to peak, and accumulated enhancement although inter-individual variation was large and no difference was found between the two stress tests for some parameters.Conclusion and Clinical Relevance: Results of this study showed that rest and stress myocardial perfusion can be assessed using DCE-CMR in dogs using the methods described. Both, adenosine dose and slice appear to affect perfusion parameters in healthy dogs and individual response to adenosine was variable.

Comparison of cerebral perfusion in perimesencephalic subarachnoid hemorrhage and aneurysmal subarachnoid hemorrhage

Perimesencephalic hemorrhage (PMH) is a benign subtype of nonaneurysmal subarachnoid hemorrhage (SAH). We aimed to investigate if cerebral perfusion in PMH is less affected than in aneurysmal SAH (aSAH). From a prospective cohort of 80 patients with spontaneous SAH, we included PMH patients (n = 15) and selected aSAH patients (n = 39) with similar clinical grade at admission (World Federation of Neurosurgeons Scale-WFNS I/II). Computed tomography (CT) perfusion was performed at < 72h and/or at 8-10days. Cerebral perfusion parameter values were compared between groups with nonparametric tests. Subgroup analyses compared PMH and aSAH patients stratified according to aneurysmal location (anterior or posterior circulation) and blood burden (Fisher grade). At < 72h, no significant differences in perfusion parameters were found between PMH and aSAH patients. At 8-10days, PMH patients had lower MTT than aSAH patients, and a trend for higher CBF. PMH patients had higher CBF and CBV at < 72h when compared to posterior circulation aSAH patients. When compared to aSAH patients with similar blood burden, PMH patients had higher CBF and lower MTT at < 72h, and lower MTT at 8-10days. PMH patients had better cerebral perfusion compared to patients with aSAH, particularly during the vasospasm time window. After stratifying for the amount of blood, PMH patients also had better cerebral perfusion in the first 72h after SAH. These results are in line with the better clinical presentation and prognosis of PMH, and possibly with a different etiology.

Can we predict necrosis intra-operatively? Real-time optical quantitative perfusion imaging in surgery: study protocol for a prospective, observational, in vivo pilot study

BackgroundCompromised perfusion as a result of surgical intervention causes a reduction of oxygen and nutrients in tissue and therefore decreased tissue vitality. Quantitative imaging of tissue perfusion during reconstructive surgery, therefore, may reduce the incidence of complications. Non-invasive optical techniques allow real-time tissue imaging, with high resolution and high contrast. The objectives of this study are, first, to assess the feasibility and accuracy of optical coherence tomography (OCT), sidestream darkfield microscopy (SDF), laser speckle contrast imaging (LSCI), and fluorescence imaging (FI) for quantitative perfusion imaging and, second, to identify/search for criteria that enable risk prediction of necrosis during gastric tube and free flap reconstruction.MethodsThis prospective, multicenter, observational in vivo pilot study will assess tissue perfusion using four optical technologies: OCT, SDF, LSCI, and FI in 40 patients: 20 patients who will undergo gastric tube reconstruction after esophagectomy and 20 patients who will undergo free flap surgery. Intra-operative images of gastric perfusion will be obtained directly after reconstruction at four perfusion areas. Feasibility of perfusion imaging will be analyzed per technique. Quantitative parameters directly related to perfusion will be scored per perfusion area, and differences between biologically good versus reduced perfusion will be tested statistically. Patient outcome will be correlated to images and perfusion parameters. Differences in perfusion parameters before and after a bolus of ephedrine will be tested for significance.DiscussionThis study will identify quantitative perfusion-related parameters for an objective assessment of tissue perfusion during surgery. This will likely allow early risk stratification of necrosis development, which will aid in achieving a reduction of complications in gastric tube reconstruction and free flap transplantation.Trial registrationClinicaltrials.gov registration number NCT02902549. Dutch Central Committee on Research Involving Human Subjects registration number NL52377.018.15.

Quantitative free-breathing dynamic contrast-enhanced MRI in hepatocellular carcinoma using gadoxetic acid: correlations with Ki67 proliferation status, histological grades, and microvascular density.

To validate a free-breathing dynamic contrast-enhanced-MRI (DCE-MRI) in hepatocellular carcinoma (HCC) patients using gadoxetic acid, and to determine the relationship between DCE-MRI parameters and histological results. Thirty-four HCC patients were included in this prospective study. Free-breathing DCE-MRI data was acquired preoperatively on a 3.0 Tesla scanner. Perfusion parameters (K trans, K ep, V e and the semi-quantitative parameter of initial area under the gadolinium concentration-time curve, iAUC) were calculated and compared with tumor enhancement at contrast-enhanced CT. The relationship between DCE-MRI parameters and Ki67 indices, histological grades and microvascular density (MVD) was determined by correlation analysis. Differences of perfusion parameters between different histopathological groups were compared. Receiver operation characteristic (ROC) analysis of discriminating high-grades (grade III and IV) from low-grades (grade I and II) HCC was performed for perfusion parameters. Significant relationship was found between DCE-MRI and CT results. The DCE-MRI derived K trans were significantly negatively correlated with Ki-67 indices (rho=-0.408, P=0.017) and the histological grades (rho=-0.444, P=0.009) of HCC, and K ep and V e were significantly related with tumor MVD (rho=-0.405, P=0.017 for K ep; and rho=0.385, P=0.024 for V e). K trans, K ep, and iAUC demonstrated moderate diagnostic performance (iAUC=0.78, 0.77 and 0.80, respectively) for discriminating high-grades from low-grades HCC without significant differences. The DCE-MRI derived parameters demonstrated weak but significant correlations with tumor proliferation status, histological grades or microvascular density, respectively. This free-breathing DCE-MRI is technically feasible and offers a potential avenue toward non-invasive evaluation of HCC malignancy.

Total liver CT perfusion imaging for evaluation on rabbit liver VX2 tumor perfusion and comparative analysis through immunohistochemisty

To investigate the correlations among total liver CT perfusion parameters, unpaired arteries (UAs) and microvessel area (MVA) in a rabbit liver VX2 tumor model, and to learn the tumoral angiogenesis condition and the mechanisms for perfusion imaging. Methods: Rabbits with or without the inoculated VX2 tumor in the liver underwent total liver CT perfusion imaging 2 weeks after the operation. Perfusion parameters included blood flow (BF), blood volume (BV), arterial liver perfusion (ALP), portal liver perfusion (PVP), hepatic perfusion index (HPI) for the tumor rim and the surrounding liver tissue. After the examination, the UAs and MVA of tumor tissues were obtained by immunohistochemical staining. The differences of perfusion parameters between the vital tumor rim and the surrounding liver tissue were compared. The correlations among perfusion parameters, UAs and MVA were analyzed. Results: There was significant difference between the CT perfusion parameters at the tumor rim and the surrounding liver tissue or liver tissue of the control group (P<0.05), but there was no significant difference between the perfusion parameters at the surrounding liver tissues of the experimental group and the control (P>0.05). There was positive correlation between UAs and MVA. UAs and MVA were positively correlated with BF, ALP and BV at the tumor rim. UAs and MVA were negatively correlated with PVP. HPI positively correlated with UAs, but it was not correlated with MVA. Conclusion: Total liver CT perfusion can provide quantitative information to evaluate the artery and portal vein perfusion of liver VX2 tumor, and to assess the degree of tumor angiogenesis.

Dynamic CT myocardial perfusion imaging identifies early perfusion abnormalities in diabetes and hypertension: Insights from a multicenter registry

BackgroundTo identify patients with early signs of myocardial perfusion reduction, a reference base for perfusion measures is needed. ObjectiveTo analyze perfusion parameters derived from dynamic computed tomography perfusion imaging (CTPI) in patients with suspected coronary artery disease (CAD), and relationship with risk factors. MethodsIn this multicenter study, coronary CT angiography (cCTA) and dynamic CTPI were performed by second-generation dual-source CT in patients suspected of CAD. Risk factors were collected from hospital records. Patients with visual perfusion defects on CTPI, previous coronary intervention, or missing risk factor details were excluded. This analysis included 98 patients (mean age ± standard deviation [SD], 59.0 ± 8.6yrs; 73 male). Global measures of left ventricular myocardial blood flow (MBF), myocardial blood volume (MBV) and volume transfer constant (Ktrans) were calculated. ResultsMean MBF was 139.3 ± 31.4 mL/100 mL/min, MBV 19.1 ± 2.7 mL/100 mL, and Ktrans 85.0 ± 17.5 mL/100 mL/min. No significant differences in perfusion parameters were found by gender or age category. Hypertension and diabetes mellitus resulted in lower perfusion parameters (hypertension vs normotension: MBV 18.5 ± 3.0 vs 19.7 ± 2.3 mL/100 mL and Ktrans 82.0 ± 18.0 vs 89.0 ± 16.0, p < 0.05; diabetes vs no diabetes: MBF 128.5 ± 31.5 vs 144.0 ± 30.5 mL/100 mL/min and MBV 17.9 ± 2.4 vs 19.4 ± 2.8 mL/100 mL, p < 0.05). In patients with hyperlipidemia, MBF was higher (146.8 ± 34.4 vs 130.7 ± 24.3 mL/100 mL/min, p < 0.05). Smoking and family history did not show perfusion parameter differences. ConclusionsDynamic CTPI identifies early perfusion disturbances in conditions like diabetes and hypertension. With further standardization, absolute perfusion measures may improve CAD risk stratification in patients without visual perfusion defects.