Low Perfusion Research Articles

Impact of the inversion time on regional brain perfusion estimation with clinical arterial spin labeling protocols

ObjectiveEvaluating the impact of the Inversion Time (TI) on regional perfusion estimation in a pediatric cohort using Arterial Spin Labeling (ASL).Materials and methodsPulsed ASL (PASL) was acquired at 3 T both at TI 1500 ms and 2020 ms from twelve MRI-negative patients (age range 9–17 years). A volume of interest (VOIs) and a voxel-wise approach were employed to evaluate subject-specific TI-dependent Cerebral Blood Flow (CBF) differences, and grey matter CBF Z-score differences. A visual evaluation was also performed.ResultsCBF was higher for TI 1500 ms in the proximal territories of the arteries (PTAs) (e.g. insular cortex and basal ganglia — P < 0.01 and P < 0.05 from the VOI analysis, respectively), and for TI 2020 ms in the distal territories of the arteries (DTAs), including the watershed areas (e.g. posterior parietal and occipital cortex — P < 0.001 and P < 0.01 from the VOI analysis, respectively). Similar differences were also evident when analyzing patient-specific CBF Z-scores and at a visual inspection.ConclusionsTI influences ASL perfusion estimates with a region-dependent effect. The presence of intraluminal arterial signal in PTAs and the longer arterial transit time in the DTAs (including watershed areas) may account for the TI-dependent differences. Watershed areas exhibiting a lower perfusion signal at short TIs (~ 1500 ms) should not be misinterpreted as focal hypoperfused areas.

Relationship between venous congestion and systemic hypoperfusion in cardiorenal syndrome

Abstract Background Renal impairment takes a relevant role in worsening clinical outcomes and increasing mortality risk in patients with heart failure (HF). In this context, the interplay between venous congestion and systemic perfusion in the pathogenesis of cardiorenal syndrome is currently a matter of extensive debate1. Purpose To investigate the relationship between renal function and hemodynamic variables, as the cardiac index and right atrial pressure, in a broad spectrum of HF patients undergoing right heart catheterization, as part of their pulmonary hypertension (PH) diagnostic work-up. Patients and methods From 1st September 2005 until 31st October 2019, hemodynamic data from 286 consecutive patients were collected, of whom 267 had available plasmatic creatinine values. The estimated glomerular filtration rate (eGFR) was calculated by using the Chronic Kidney Disease Epidemiology Collaboration formula. The overall study population was stratified in no PH group, pre-capillary PH group and post-capillary PH group, on the basis of the available hemodynamic values of mean pulmonary arterial pressure and pulmonary artery wedge pressure. Results Of the overall population, 46.1% of them were male, the mean age at the right heart catheterization was 65.5±13.7 years, and the mean eGFR value was 70.0±0.2 mL/min/1.73 m2. On the basis of hemodynamic parameters, 71 patients constituted the no PH group, 107 the pre-capillary PH group, and 63 the post-capillary PH group. Post-capillary PH patients were significantly older than both no PH and pre-capillary PH subjects (69.4±11.7 years; 61.2±16.7 years and 65.7±12.9 years respectively, p=0.003). eGFR was significantly lower in the post-capillary PH group, compared to both no PH group (63.1±22.8 mL/min/1.73 m2 vs. 73.0±23.9 mL/min/1.73 m2, p=0.029) and pre-capillary PH group (63.1±22.8 mL/min/1.73 m2 vs. 71.6±26.6 mL/min/1.73 m2, p=0.041). In post-capillary PH group, multivariate logistic regression analysis showed a significant correlation between eGFR &amp;lt;60 mL/min/1.73 m2 and both reduced cardiac index (Odds ratio [OR] 0.05, 95% confidence interval [CI] 0.00 to 0.72, p=0.027) and right atrial pressure (OR 0.75, 95% CI 0.57 to 0.99, p=0.039), compared to no PH group and pre-capillary PH group. Conclusions A significant association between renal impairment and both low systemic perfusion and venous congestion, was found in patients with post-capillary PH, rather than in other hemodynamic subsets. Further investigations are needed to disentangle the impact of the both sides of circulation on renal function, in different hemodynamic phenotypes. Funding Acknowledgement Type of funding sources: None.

Thyroid Status and Brain Circulation: The Rotterdam Study.

ContextWhether thyroid dysfunction is related to altered brain circulation in the general population remains unknown.ObjectiveWe determined the association of thyroid hormones with different markers of brain circulation within community-dwelling elderly people.MethodsThis was a population-based study of 3 subcohorts of the Rotterdam Study, starting in 1989, 2000, and 2006. A total of 5142 participants (mean age, 63.8 years; 55.4% women), underwent venipuncture to measure serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4). Between 2005 and 2015, all participants underwent phase-contrast brain magnetic resonance imaging to assess global brain perfusion (mL of blood flow/100 mL of brain/minute). Arteriolar retinal calibers were assessed using digitized images of stereoscopic fundus color transparencies in 3105 participants as markers of microcirculation. We investigated associations of TSH, FT4 with brain circulation measures using (non)linear regression models.ResultsFT4 (in pmol/L) levels had an inverse U-shaped association with global brain perfusion, such that high and low levels of FT4 were associated with lower global brain perfusion than middle levels of FT4. The difference in global brain perfusion between high FT4 levels (25 pmol/L) and middle FT4 levels (FT4 = 15 pmol/L; P nonlinearity = .002) was up to –2.44 mL (95% CI –4.31; –0.56). Higher and lower levels of FT4, compared with middle FT4 levels, were associated with arteriolar retinal vessels (mean difference up to –2.46 µm, 95% CI –4.98; 0.05 for lower FT4).ConclusionThese results suggest that thyroid dysfunction could lead to brain diseases such as stroke or dementia through suboptimal brain circulation that is potentially modifiable.

Predicting Overall Survival Time in Glioblastoma Patients Using Gradient Boosting Machines Algorithm and Recursive Feature Elimination Technique.

Simple SummaryDespite the highly aggressive nature of glioblastoma multiforme (GBM), survival time is in practice highly variable, and some of the patients remain stable for several years after treatment. The aim of this study was to develop a machine learning method that could precisely predict survival time of GBM patients. To do so, we integrated multi-modal MRI with non-supervised and supervised machines. We first identified compartments of the tumor then extracted their features. Then relevant useful features were selected by Random Forest-Recursive Feature Elimination (RF-RFE) to feed into Gradient Boosting Machine Algorithm with the aim of classifying GBM patients. By selecting the most relevant features, multi-modality MRI with tumor segmentation provided valuable independent and complete features to feed a machine learning model. Additionally, advanced machine-learning methods such as RF-RFE and GBoost are powerful tools for data mining. Hand-crafted feature-based methods have shown promising results, but there is no systematic way to determine survival-related hand-crafted features and existing methods mostly rely on experience.Despite advances in tumor treatment, the inconsistent response is a major challenge among glioblastoma multiform (GBM) that lead to different survival time. Our aim was to integrate multimodal MRI with non-supervised and supervised machine learning methods to predict GBM patients’ survival time. To this end, we identified different compartments of the tumor and extracted their features. Next, we applied Random Forest-Recursive Feature Elimination (RF-RFE) to identify the most relevant features to feed into a GBoost machine. This study included 29 GBM patients with known survival time. RF-RFE GBoost model was evaluated to assess the survival prediction performance using optimal features. Furthermore, overall survival (OS) was analyzed using univariate and multivariate Cox regression analyses, to evaluate the effect of ROIs and their features on survival. The results showed that a RF-RFE Gboost machine was able to predict survival time with 75% accuracy. The results also revealed that the rCBV in the low perfusion area was significantly different between groups and had the greatest effect size in terms of the rate of change of the response variable (survival time). In conclusion, not only integration of multi-modality MRI but also feature selection method can enhance the classifier performance.

Detection of visual and frontoparietal network perfusion deficits in Parkinson’s disease dementia

Mild cognitive impairment of Parkinson's disease (PD) may be an early manifestation that may progressively worsen to dementia. Cognitive decline has been associated with changes in the brain perfusion pattern. This study aimed to evaluate cerebral blood flow (CBF) deficits specific to different stages of cognitive decline.Seventeen patients with cognitively normal PD (PD-CN), 18 patients with PD with mild cognitive impairment (PD-MCI), and 16 patients with PD with dementia (PDD) were included in this study. The participants were scanned using a 3 T Philips MRI scanner. Arterial spin labelling magnetic resonance (ASL-MR) images were acquired, followed by calculation of the CBF maps, and registration onto the MNI152 brain atlas. A whole-brain voxel-based CBF comparison was performed among the patient groups using age as a covariate. The mean age of patients with PDD was significantly higher than that of patients with PD-MCI (P = 0.015) and PD-CN (P = 0.001). The CBF values of the three groups were significantly different in the left cuneus of the visual network (VN), left inferior frontal gyrus of the frontoparietal network (FPN), and left dorsomedial nucleus of the thalamus. PDD had lower perfusion values than PD-MCI group in the same regions detected in the main group analysis. Additionally, comparison of PDD with PD-CN and non-demented groups revealed that the perfusion reduction extended into the bilateral cuneus of the VN, bilateral thalami, and left inferior frontal gyrus of the FPN.PDD could be separated from PD-MCI and PD-CN stages with CBF deficits in non-dopaminergically mediated posterior and dopaminergically mediated frontal networks.

Visceral Fat Accumulation Is Related to Impaired Pancreatic Blood Perfusion and Beta-Cell Dysfunction in Obese Women

Aims/Hypothesis: Beta-cell failure plays a fundamental role in type 2 diabetes mellitus (T2DM) development. It has been shown that the beta-cells are among the most sensitive to hypoxia. We aimed to analyze whether decrease in pancreatic perfusion relates to 1/decline in beta-cell function and 2/visceral fat accumulation in patients with T2DM. Methods: Fifteen women with T2DM on metformin therapy alone and fifteen women of comparable age and BMI without prediabetes/diabetes were cross-sectionally examined: clinical and anthropometric examination, fast sampled intravenous glucose tolerance test (FSIVGTT), dynamic contrast-enhanced magnetic resonance imaging to assess pancreatic perfusion (area under the curve of postcontrast saturation, AUC_TSIC), and visceral adiposity (VAT, calculated from transverse sections at the level L2–L5 vertebrae). Results: Pancreatic blood perfusion (AUC_TSIC) did not differ between groups (p = 0.273), but it negatively correlated with BMI (r = −0.434, p = 0.017), WHR (r = −0.411, p = 0.024), and VAT (r = −0.436, p = 0.016) in both groups. Moreover, AUC_TSIC in the head of the pancreas negatively correlated with the level of fasting glycemia (r = −0.401, p = 0.028) and HOMA-IR (r = −0.376, p = 0.041). Discussion/Conclusion: We showed that decreased pancreatic perfusion did not relate to beta-cell dysfunction in early stages of T2DM development, but it was related to VAT, insulin resistance, and higher fasting glycemia. Furthermore, lower pancreatic perfusion was related to VAT, insulin resistance, and higher fasting glycemia.

Perfusion and Permeability MRI Predicts Future Cavernous Angioma Hemorrhage and Growth.

Cerebral cavernous angioma (CA) is a capillary vasculopathy affecting more than a million Americans with a small fraction of cases demonstrating lesional bleed or growth with major clinical sequelae. Perfusion and permeability are fundamental features of CA pathophysiology, but their role as prognostic biomarkers is unclear. To investigate whether perfusion or permeability lesional descriptors derived from dynamic contrast-enhanced quantitative perfusion (DCEQP) magnetic resonance imaging (MRI) can predict subsequent lesional bleed/growth in the year following imaging. Single-site case-controlled study. Two hundred and five consecutively enrolled patients (63.4% female). Three-Tesla/T1 -mapping with contrast-enhanced dynamic two-dimensional (2D) spoiled gradient recalled acquisition (SPGR) sequences. Prognostic associations with bleed/growth (present or absent) in the following year were assessed in 745 CA lesions evaluated by DCEQP in the 205 patients in relation to lesional descriptors calculated from permeability and perfusion maps. A subgroup of 30 cases also underwent peripheral blood collection at the time of DCEQP scans and assays of plasma levels of soluble CD14, IL-1β, VEGF, and soluble ROBO4 proteins, whose weighted combination had been previously reported in association with future CA bleeding. Mann-Whitney U-test for univariate analyses. Logistic regression models minimizing the Bayesian information criterion (BIC), testing sensitivity and specificity (receiver operating characteristic curves) of weighted combinations of parameters. The best prognostic biomarker for lesional bleed or growth included brainstem lesion location, mean lesional permeability, and low-value perfusion cluster mean (BIC=201.5, sensitivity=77%, specificity=72%, P < 0.05). Adding a previously published prognostic plasma protein biomarker improved the performance of the imaging model (sensitivity=100%, specificity=88%, P < 0.05). A combination of MRI-based descriptors reflecting higher lesional permeability and lower perfusion cluster may potentially predict future bleed/growth in CAs. The sensitivity and specificity of the prognostic imaging biomarker can be enhanced when combined with brainstem lesion location and a plasma protein biomarker of CA hemorrhage. 2 TECHNICAL EFFICACY: Stage 5.

Total arch replacement in octogenarians.

OBJECTIVESWe investigated the effect of a preoperative age ≥80 years on postoperative outcomes in patients who underwent isolated elective total arch replacement using mild hypothermic lower body circulatory arrest with bilateral antegrade selective cerebral perfusion.METHODSA total of 140 patients who had undergone isolated elective total arch replacement between January 2007 and December 2020 were enrolled in the present study. We compared postoperative outcomes between 30 octogenarian patients (≥80 years old; Octogenarian group) and 110 non-octogenarian patients (≤79 years old; Non-Octogenarian group).RESULTSOverall 30-day mortality and hospital mortality were 0% in both groups, and there was no significant difference in overall survival between the 2 groups (log-rank test, P = 0.108). Univariable Cox proportional hazard analysis showed that age as continuous variable was only the predictor of mid-term all-cause death (hazard ratio 1.08, 95% confidence interval 1.01–1.16; P = 0.037), but not in the Octogenarians subgroup (P = 0.119).CONCLUSIONSPreoperative age ≥80 years is not associated with worse outcomes postoperatively after isolated elective total arch replacement with mild hypothermic lower body circulatory arrest and bilateral antegrade selective cerebral perfusion.

Effects of ulinastatin on renal perfusion evaluated by Doppler ultrasonography in a porcine model of septic shock.

The present study aimed to evaluate the effect of ulinastatin (UTI) on renal perfusion using Doppler ultrasonography in a porcine model of septic shock induced by smoking inhalation and live methicillin-resistant Staphylococcus aureus instillation. A total of 32 healthy Landrace pigs were randomly assigned into the following four groups: Sham group (SH; n=5), septic shock group (SS; n=9), septic shock treated with vancomycin (15 mg/kg) group (VAN; n=9) and septic shock treated with UTI (50,000 U/kg) + vancomycin (UTI; n=9) group. Renal perfusion was evaluated by contrast-enhanced ultrasound (CEUS) at baseline and at the end of the protocol (24 h). The spectrum of interlobar or arcuate artery was selected to calculate the corrected resistive index (cRI). Sulphur hexafluoride microbubbles were bolus injected via a venous catheter. The peak intensity (Pi) and area under curve (AUC) were calculated using a time-intensity curve. Compared with the baseline group, cRI was increased significantly at the end of the protocol, except for that in the SH group, whereas Pi decreased significantly after injury in all experimental groups but was higher in the UTI group compared with that in the SS and VAN groups (both P<0.001). Linear correlation was found between the cardiac output (CO) and Pi (R2=0.752; P<0.001). The AUC was significantly decreased after injury in the SS and VAN groups compared with the baseline group. All parameters detected by CEUS were improved in the UTI group, and significant differences were found between the UTI and SS or VAN group (all P<0.05). In conclusion, acute renal injury, which occasionally occurs during septic shock, is accompanied with a significantly lower perfusion rate in the renal microcirculation. By contrast, UTI can significantly improve renal perfusion, which can be reliably evaluated using CEUS.

Peripheral perfusion index and diagnostic accuracy of the post-ROSC electrocardiogram in patients with medical out-of-hospital cardiac arrest

AimA 12-lead electrocardiogram (ECG) after the return of spontaneous circulation (ROSC) is recommended to diagnose a ST-segment elevation myocardial infarction (STEMI). In the early post-ROSC phase, the ECG can show signs of ischemia not necessarily of coronary origin and post-ROSC hypoperfusion could affect ECG reliability. We sought for an association between peripheral perfusion index (PI) values after ROSC and the percentage of false-positive ECG for STEMI. MethodsWe considered all the consecutive patients with sustained ROSC after OHCA, admitted to the Fondazione IRCCS Policlinico San Matteo (Pavia) between January 1st, 2015 and December 31st, 2020. ECGs were defined false-positive if meeting the STEMI criteria but without a critical obstructive coronary artery disease worthy of treatment. The mean value of PI over 30 min-monitoring (MPI30) were calculated. ResultsAmong 351 eligible patients post-ROSC ECG, PI monitoring and an invasive coronary angiography (ICA) were available in 84 cases. The rate of false positive was 16/54 (29.6%) and it differed significantly in the three MPI30 tertiles [T1 (0.2–1): 28.6%; T2 (1.1–2.5): 24.1%; T3 (2.6–6.9): 3.7%, p = 0.04; p for trend = 0.02]. Cardiac arrest duration [OR 1.06 (95 %CI 1–1.1), p = 0.007] and MPI30 [T3 vs T1: OR 0.09 (95 %CI 0.01–0.8), p = 0.03] were significantly associated with the probability of acquiring a false-positive ECG. This association was also confirmed when MPI30 was adjusted for cardiac arrest duration [OR 0.2 (95 %CI 0.1–0.6), p=<0.001]. ConclusionsThe rate of false-positive ECG for STEMI after ROSC is related with low perfusion. Our results could help to identify the adequate candidates for an immediate ICA.

Radiology- and gene-based risk stratification in small renal cell carcinoma: A preliminary study.

PurposeMost small renal cell carcinomas (small RCCs) will remain indolent after detection, but some stage I RCCs still metastasize. There are no risk-stratification imaging factors that could be used to identify poor-prognosis patients based on genomic profiling. Here, we evaluated the relationships between imaging parameters and RNA expressions in small RCC and attempted to identify imaging factors that could be used as effective biomarkers.MethodsWe acquired biopsy specimens of 18 clear cell carcinomas that had undergone perfusion CT (pCT) and MRI between April 2018 and March 2019. We performed RNA sequencing, assessed RNA expressions, and calculated each tumor’s cell-cycle progression (CCP) score, which has prognostic value in predicting metastatic progression. We classified the tumors into two groups: clear cell type A (ccA) and type B (ccB). CcA has better survival compared to ccB. We evaluated the following characteristics of each tumor: tumor size, presence of pseudocapsule, and fat. We used the pCT and MRI to measure each tumor’s volume transfer constant (Ktrans), rate constant (Kep), extracellular extravascular volume fraction (VE), fractional plasma volume (VP), and apparent diffusion coefficient (ADC). The correlations between these small RCC imaging parameters and the tumor size and RNA expressions were determined.ResultsThe tumor size was significantly correlated with Kep and inversely correlated with VE, VP, ADC, and hallmark angiogenesis. The CCP score was significantly inversely correlated with Ktrans and Kep. The ccA tumors tended to show a pseudocapsule on MRI.ConclusionTumor size was correlated with low perfusion, but not with prognostic factors based on genomic profiling. Imaging parameters (e.g., Ktrans and Kep) and tumor characteristics (e.g., pseudocapsule) may enable gene-based risk stratification in small RCC.

Laboratory evaluation of performance of pulse oximeters from six different manufacturers during motion artifacts produced by Fluke 2XL SpO2 simulator.

We performed laboratory evaluation of six pulse oximeters from different manufacturers using the Fluke 2XL SpO2 simulator. The pulse oximeter probes were labeled 1 through 6 and tested using the two pre-programed preset functions of the Fluke 2XL SpO2 simulator, level 01 and level 02, for their performance in the presence of motion artifacts. The pulse oximeters were also tested at low perfusion index (PI) settings. The accuracy of the individual probes was ranked as good, mediocre, or poor based on the degree of deviation of the measured SpO2 and pulse rate (PR) by the probes from that generated by the simulator in both the presence and absence of motion artifacts and at lower PI. In preset level 01, probes numbered 1, 2, and 6 performed flawlessly, probes numbered 3, 4, and 5 performed poorly. In preset level 02, all probes performed well in the absence of motion artifacts. When probes were attached in the absence of motion, but readings were recorded after the emergence of motion artifacts, probes 1, 2, and 6 continued to perform well. However, the performance of probes 3, 4, and 5 deteriorated. When probes were attached directly in the presence of motion artifacts, probes 2 and 6 performed well, whereas all other probes performed poorly. Successively lowering the PI degraded performance of probes 3, 4, and 5 at extremely low PI. It is observed that during motion and/or low PI conditions, multiple probes see deterioration in performance.

Enhanced perfusion of elliptical wound closures using a novel adhesive suture retention device.

Background and AimsThe purpose of this investigation was to test the hypothesis that a novel adhesive retention suture device (ARSD) can increase perfusion at elliptical wound closures by distributing stress away from the suture site.MethodsStress in the skin around a suture both with and without support from an ARSD was evaluated using a finite element model. A single‐center, randomized split‐scar comparison trial using laser speckle contrast analysis was used to quantify the perfusion at elliptical wound closures in human patients both with and without an ARSD.ResultsThe finite element model revealed that the ARSD promoted load transfer to the skin over a larger area, thus reducing the local stress and deformation in the skin around the suture site. Results from the split‐scar study showed a mean improvement of 25% perfusion units with the ARSD, and the improvement was statistically significant (p = 0.002).ConclusionThe reduction in local stress and enhanced perfusion around the suture site reveals the potential benefit of using an ARSD to enable more efficient healing by avoiding complications associated with both low perfusion and skin tearing, such as dehiscence, infection, and cheese wiring.

A-85 Differences in Cerebral Blood Perfusion with Individuals Diagnosed with Cluster B Personality Disorders

Abstract Objective To identify regional cerebral blood flow (rCBF) differences between individuals with DSM-IV diagnosis of Cluster B Personality Disorders (PDB) and healthy controls. Method Healthy controls (n = 81, Mage = 41.9, 53.0% female, 42.0% Caucasian) and persons diagnosed by psychiatric examination with PDB (n=, Mage = 34.12, 71.5% female, 69.8% Caucasian) were selected from a deidentified adult clinical outpatient database. Those with comorbid diagnoses were included. Significant differences (alpha = 0.005) were found for age [t(195) = −3.62], gender [χ2(2) = 7.1], and race [χ2(12) = 23.82] between groups. Mean age [t(523) = 2.09, p = 0.037) and gender [t(532) = −2.653, p = 0.008] different significantly between groups. No significant mean difference was found for education [t(523) = 0.832, p = 0.406]. Results Significant rCBF differences were noted in the cerebellum [left:F(1,192) = 10.5; right:F(1,192) = 4.6], limbic system [left:F(1,192) = 7.8; right:F(1,192) = 5.0], and basal ganglia [left:F(1,192) = 12.3; right:F(1,192) = 6.7]. Group means comparisons indicated higher perfusion in the cerebellum for the PDB group. Lower perfusion was found in the limbic system and basal ganglia in the PDB group. Conclusion Results observed in this study are concurrent with previous literature. PDB demonstrates higher activity in the cerebellum which contains inhibitory neurotransmitters, like Purkinje cells. The increased blood flow to cerebellar circuits may be related to the explicit self-recognition of negative emotion reported in PDB. Hypoperfusion found in the limbic system could be linked to impaired emotional responses. Apathy experienced in PDB may be accounted for by the low perfusion in the highly dopaminergic pathway in the basal ganglia. Further research should assess how different comorbidities with PDB affect perfusion.

A-87 Regional Cerebral Blood Flow in Self-Reported Somatic Anxiety

Abstract Objective To identify regional cerebral blood flow (rCBF) differences between individuals who self-reported either low or high symptoms of somatic anxiety. Method Individuals who reported low levels of somatic anxiety (0-20th percentile;n = 8962,Mage = 39.2,39.2% female,62.6% Caucasian) and individuals who reported high levels of somatic anxiety (80-100th percentile;n = 6427,Mage = 40.9,39.0% female,69.5% Caucasian) were selected from a deidentified adult clinical outpatient database. Those with comorbid diagnoses were included. Significant differences (alpha = 0.001) were found for age [t(15387) = 6.3], and race [χ2(15) = 119.4] between groups and therefore were controlled. Results Significant rCBF differences were noted bilaterally in the frontal lobe [left: F(1,15,384) = 16.4; right: F(1,15,384) = 13.2] and motor-sensory strip [left: F(1,15,384) = 4.3; right: F(1,15,384) = 5.1]. Group means comparisons indicated higher perfusion in the frontal lobe of the high levels of somatic anxiety group. Lower perfusion was found in the motor sensory strip of the high levels of somatic anxiety group. No significant differences were found bilaterally in the cerebellum, limbic system, basal ganglia, vermis, or occipital, parietal, or temporal lobes. Conclusion Results indicated that individuals who report higher levels of somatic anxiety have higher perfusion in the frontal lobes and lower perfusion motor-sensory strip. Previous literature SPECT studies have found a link between individuals with panic disorder and increased activity in the right medial and superior frontal lobes. No research was found for anxiety in the motor-sensory strip. Limitations included the reliance on self-report measures of anxiety in place of clinical measures and the potential mediating effect of medication on somatic symptoms. Future research should examine perfusion in the motor-sensory strip, use clinical measures of anxiety, and control for mediation use.

A-67 Measuring Regional Cerebral Blood Flow with Single-Photon Emission Computed Tomography (SPECT) in Obsessive–Compulsive Disorder

Abstract Objective To identify regional cerebral blood flow (rCBF) differences between individuals with Obsessive–Compulsive Disorder (OCD) and healthy controls. Mehtods: Healthy controls (n = 81, Mage = 41.9, 53.0% female, 42.0% Caucasian) and persons diagnosed by psychiatric examination with OCD (n = 1020, Mage = 34.8, 33.6% female, 66.3% Caucasian) were selected from a deidentified adult clinical outpatient database. Those with comorbid diagnoses were included. Significant differences (alpha = 0.001) were found for age [t(1099) = −4.4], gender [χ2(2) = 25.7], and race [χ2(12) = 30.1] between groups and therefore were controlled for. Significant rCBF differences were noted in the cerebellum [left:F(1,1096) = 21.6; right:F(1,1096) = 18.3], limbic system [left:F(1,1096) = 12.2; right:F(1,1096) = 10.4], and basal ganglia [left:F(1,1096) = 18.6; right:F(1,1096) = 18.3]. Results Group means comparisons indicated higher perfusion in the cerebellum for the OCD group. Lower perfusion was found in the limbic system and basal ganglia in the OCD group. This study found higher perfusion in the cerebellum among the OCD group. Previous research found increased rCBF in the left cerebellum in OCD before pharmacotherapy. In the right cerebellum, increased rCBF was found among participants with early-onset OCD. Conclusion Overall, there is limited research on the cerebellum because of its use as a reference point. No research was found regarding the limbic system in OCD using SPECT; however, other neuroimaging found increased amygdala reactivity to emotional face stimuli. This study found lower perfusion in the basal ganglia among the OCD group. Previous research found hypoperfusion in the right; however, hypoperfusion in the left was not significant. Updated OCD and rCBF research with SPECT are needed. Limitations included the inclusion of comorbidities and use of DSM-IV-TR rather than DSM-5 diagnosis criteria.

Endovascular repair of aortic perforation and type B aortic dissection after axillary intra-aortic balloon pump insertion

We present the successful endovascular repair of an iatrogenic aortic dissection in a 57-year-old woman with decompensated heart failure. An intra-aortic balloon pump was inserted in the patient via a percutaneous axillary approach for circulatory support. Six days later, she developed symptoms of abdominal pain and lower extremity malperfusion. Computed tomography angiography demonstrated a type B aortic dissection with associated retroperitoneal hematoma secondary to aortic perforation. The patient underwent emergent endovascular aortic repair and intra-aortic balloon pump removal with return of lower extremity perfusion. She recovered well and underwent heart and kidney transplant less than 2 months postoperatively.

A Reperfusion BOLD-MRI Tissue Perfusion Protocol Reliably Differentiate Patients with Peripheral Arterial Occlusive Disease from Healthy Controls.

There is no established technique that directly quantifies lower limb tissue perfusion. Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) is an MRI technique that can determine skeletal muscle perfusion. BOLD-MRI relies on magnetic differences of oxygenated and deoxygenated hemoglobin, and regional changes in oxy/deoxyhemoglobin ratio can be recorded by T2* weighted MRI sequences. We aimed to test whether BOLD-MRI can differentiate lower limb tissue perfusion in peripheral arterial occlusive disease (PAOD) patients and healthy controls. Twenty-two PAOD patients and ten healthy elderly volunteers underwent lower limb BOLD-MRI. Reactive hyperemia was provoked by transient cuff compression and images of the gastrocnemius and soleus muscles were continuously acquired at rest, during ischemia and reperfusion. Key BOLD parameters were baseline T2* absolute value and time to T2* peak value after cuff deflation (TTP). Correlations between imaging parameters and ankle-brachial index (ABI) was investigated. The mean TTP was considerably prolonged in PAOD patients compared to healthy controls (m. gastrocnemius: 111 ± 46 versus 48 ± 22 s, p = 0.000253; m. soleus: 100 ± 42 versus 41 ± 30 s, p = 0.000216). Both gastrocnemius and soleus TTP values correlated strongly with ABI (−0.82 and −0.78, p < 0.01). BOLD-MRI during reactive hyperemia differentiated most PAOD patients from healthy controls. TTP was the most decisive parameter and strongly correlated with the ABI.

Intravoxel Incoherent Motion Magnetic Resonance Imaging in Skeletal Muscle: Review and Future Directions.

Throughout the body, muscle structure and function can be interrogated using a variety of noninvasive magnetic resonance imaging (MRI) methods. Recently, intravoxel incoherent motion (IVIM) MRI has gained momentum as a method to evaluate components of blood flow and tissue diffusion simultaneously. Much of the prior research has focused on highly vascularized organs, including the brain, kidney, and liver. Unique aspects of skeletal muscle, including the relatively low perfusion at rest and large dynamic range of perfusion between resting and maximal hyperemic states, may influence the acquisition, postprocessing, and interpretation of IVIM data. Here, we introduce several of those unique features of skeletal muscle; review existing studies of IVIM in skeletal muscle at rest, in response to exercise, and in disease states; and consider possible confounds that should be addressed for muscle-specific evaluations. Most studies used segmented nonlinear least squares fitting with a b-value threshold of 200 sec/mm2 to obtain IVIM parameters of perfusion fraction (f), pseudo-diffusion coefficient (D*), and diffusion coefficient (D). In healthy individuals, across all muscles, the average ± standard deviation of D was 1.46 ± 0.30 × 10-3 mm2 /sec, D* was 29.7 ± 38.1 × 10-3 mm2 /sec, and f was 11.1 ± 6.7%. Comparisons of reported IVIM parameters in muscles of the back, thigh, and leg of healthy individuals showed no significant difference between anatomic locations. Throughout the body, exercise elicited a positive change of all IVIM parameters. Future directions including advanced postprocessing models and potential sequence modifications are discussed. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Segmental mandibular reconstruction in patients with poor lower extremity perfusion, vessel-depleted necks and/or profound medical frailty.

Options for segmental mandibular reconstruction in patients poorly suited to undergo fibula free flap (FFF). Although FFF is the current 'gold standard' for segmental mandibular reconstruction, other reconstructive options must be considered when FFF is contraindicated or disfavoured and/or patient frailty precludes a lengthy anaesthetic. In addition to various nonvascularized and soft tissue only reconstructions, excellent osseous free flap alternatives for functional segmental mandibular reconstruction may be employed. The subscapular system free flaps (SSSFF) may be ideal in frail and/or elderly patients, as SSSFF allows for early mobility and does not alter gait. In extensive and/or symphyseal defects, functional mandibular reconstruction in lieu of a free flap is extremely limited. Pedicled segmental mandibular reconstructions remain reasonable options, but limited contemporary literature highlights unpredictable bone graft perfusion and poor long-term functional outcomes. There are several excellent free flap alternatives to FFF in segmental mandibular reconstruction, assuming adequate cervical recipient vessels are present. On the basis of the current literature, the optimal mandibular reconstruction for the medically frail, elderly and/or patients with extreme vessel-depleted necks is limited and debatable. In qualifying (i.e. limited, lateral) defects, soft tissue only reconstructions should be strongly considered when osseous free flaps are unavailable.