Improving duplex ultrasound methods for diagnosing functional popliteal artery entrapment syndrome.

OBJECTIVES: Popliteal artery entrapment syndrome (PAES) is a rare condition where musculoskeletal structures compress the popliteal artery (POPA) leading to vascular compromise. This study investigates the effect of dynamic plantar- and dorsi-flexion loading on POPA hemodynamic parameters to develop a robust diagnostic ultrasound-based protocol for diagnosing functional PAES. METHODS: Healthy individuals (n = 20), recreational athletes (n = 20), and symptomatic (n = 20) PAES patients were consented. Triplex ultrasound imaging of lower limb arteries was performed (n = 120 limbs). Proximal and distal POPA's in dorsi-/plantar-flexion, in prone and erect positions, were imaged at rest and flexion. Peak systolic velocities (cm/s) and vessel diameter (antero-posterior, cm) was measured. RESULTS: Distal vessel occlusion was noted across all three groups whilst prone during plantar-flexion (62.7%). POPA occlusion was only noted in the proximal vessel within the patient group (15.8%). When prone, 50% of control (n = 40 limbs), 70% of athletes (n = 40 limbs), and 65% of patients (n = 40 limbs) had distal POPA occlusion in plantar-flexion. When prone, recreational athletes (5%), and patients (12.5%) had distal POPA compression under dorsi-flexion. POPA occlusions with the patient in erect position were only noted in the symptomatic patient group under both dorsi-flexion (15.8%) and plantar-flexion (23.7%). CONCLUSION: Compression of the POPA on ultrasound should not be the sole diagnostic criteria for PAES. POPA compression exists in asymptomatic individuals, primarily under prone plantar-flexion. To reduce false positives, ultrasound-based protocols should focus on scanning patients in the erect position only to diagnose PAES, rather than asymptomatic POPA compression. A distinction should be made between the two.

Accelerated Measurement of Carotid Plaque Volume Using Artificial Intelligence Enhanced 3D Ultrasound.

BACKGROUND: Carotid plaque volume (CPV) can be measured by 3D ultrasound and may be a better predictor of stroke than stenosis, but analysis time limits clinical utility. This study tested the accuracy, reproducibility, and time saved of using an artificial intelligence (AI) derived semiautomatic software to measure CPV ("auto-CPV"). METHODS: Three-dimensional (3D) ultrasound images for 121 individuals were analyzed by 2 blinded operators to measure auto-CPV. Corresponding endarterectomy specimen volumes were calculated by the validated saline suspension technique. Inter-rater and intrarater agreement plus accuracy compared with the volume of the endarterectomized plaque were calculated. Measurement times were compared with previous manual CPV measurement. RESULTS: The mean difference between auto-CPV and surgical volume was small at (±s.d.) [95% confidence interval [CI]] 0.06 (0.24) [-0.41 to 0.54] cm3. The intraclass correlation (ICC) was strong at 0.91; 95% CI 0.86-0.94. Interobserver and intraobserver error was low with mean difference (±s.d.) [95%CI] 0.01 (0.26) [-0.5 to 0.5] cm3 and 0.03 (0.19) [-0.35 to 0.40] cm3 respectively. Both showed excellent ICC with narrow confidence intervals, ICC = 0.90; 95% CI (0.85-0.94) and ICC = 0.95; 95% CI (0.92-0.96). Auto-CPV measurement took 43% the time of manual planimetry; median (IQR) 05:39 (01:58) minutes compared to 13:05 (04:15) minutes, Wilcoxon rank-sum test, P < 0.01. CONCLUSIONS: Auto-CPV assessment is accurate, reproducible, and significantly faster than manual planimetry. Improved feasibility means that the utility of CPV can be assessed in large population studies to stratify risk in asymptomatic carotid disease or assess response to medical treatment.

Aneurysm Geometry Analyzed by the Novel Three-Dimensional Tomographic Ultrasound Relates to Abdominal Aortic Aneurysm Growth.

BACKGROUND: Abdominal aortic aneurysms (AAAs) are increasingly screen-detected and many small aneurysms enter surveillance. Computed tomography identifies characteristics that can predict subsequent AAA growth but ionizing radiation and nephrotoxic contrast disadvantage its use in surveillance. We investigated whether duplex and 3-dimensional tomographic ultrasound identified features associated with AAA growth in patients on AAA surveillance. METHODS: Duplex and three-dimensional tomographic ultrasound imaging was performed independently by 2 vascular scientists in 128 AAA surveillance patients who all had AAA growth measured over at least 2 years. Diameter, cross-sectional area, length, volume, wall thickness/volume, and intraluminal thrombus were measured. Pulsatility using maximum systolic and minimum diastolic diameters corrected for diameter and distensibility (consisting of strain and stiffness) were also calculated. RESULTS: AAA growth rate correlated with AAA diameter (r 0.43), volume (r 0.46), and cross-sectional area (r 0.42) (P < 0.01). Measuring wall thickness was inaccurate, but wall volume (corrected for AAA volume) inversely related to growth rate (r -0.43, P < 0.01). On a multivariate analysis, diameter and wall volume (r2adjusted 0.22, P < 0.01) improved prediction of growth rate compared with diameter alone (r2adjusted 0.18, P < 0.01). Intraluminal thrombus volume, strain distensibility, and elastic distensibility were not significantly associated with AAA growth. CONCLUSIONS: AAA growth most strongly related to AAA volume and inversely to wall volume. AAA volume and wall volume may prove useful in the prediction of AAA growth rates.

Evaluating Potential Autologous Bypass Grafts with Tomographic Three-Dimensional Ultrasound Compared with Standard Color Duplex.

BACKGROUND: Vein mapping using duplex ultrasound (DUS) is a routine in selecting optimal autologous bypass grafts (aBG) but is time consuming and operator-dependent. Tomographic three-dimensional (3D) ultrasound (tUS), using free-hand electromagnetic tracking, allows cardiac and vascular surgeons to view 3D images of the entire length of the potential bypass graft. This study compares tUS with DUS in the evaluation of potential autologous grafts for coronary and lower limb bypass. METHODS: Both DUS and tUS imaging of 434 potential autologous grafts (364 long, 22 short saphenous veins, and 48 radial artery) immediately before bypass surgery were compared. The time in minutes to evaluate each aBG was recorded. Surgeons scored the quality of the aBG at operation. A score of 5 was in complete agreement with preoperative imaging with scores of 4 considered "good". RESULTS: Most operating surgeons (113, 57%) preferred interpreting the tUS images and felt that this technology could replace DUS completely. The choice of aBG would have been changed as a result of tUS images in 64 (32%) cases. DUS imaging took a mean (+/-sd) of 08:26 ± 04:44 minutes compared with only 01:00 ± 00:25 minutes for tUS (P < 0.001). However, processing the tUS images, which is currently done manually by the vascular scientist, took significantly longer at 19:31 ± 12:41 minutes compared with 09:03 ± 09:12 minutes for reporting DUS (P < 0.001). CONCLUSIONS: Surgeons preferred to see tUS images of the potential aBG themselves rather than relying on DUS reports. tUS images were significantly quicker than DUS to acquire but needed more processing time.

Comparison Between Below Knee Contrast Enhanced Tomographic 3D Ultrasound and CT, MR or Catheter Angiography for Peripheral Artery Imaging.

OBJECTIVE: Clear imaging of below knee and foot arteries is essential to plan distal reconstructions. Contrast enhanced tomographic 3D ultrasound (CEtUS) is novel and entirely safe with no exposure to ionising radiation or nephrotoxic contrast. In the present study, inter- and intra-observer agreement of CEtUS was calculated, and compared with below knee angiography. METHODS: In the same week as computed tomography, magnetic resonance or catheter angiography, CEtUS was performed using intravenous 1.2 mL bolus injections of Sonovue with a maximum of 5 mL administered per patient. CEtUS was reported by a vascular scientist blinded to the angiograms reported by a consultant radiologist. Images were compared using a modified Society of Vascular Surgery (SVS) runoff score. RESULTS: Of the 181 patients recruited with peripheral arterial disease, 20 were excluded from analysis as they withdrew consent, could not be cannulated, or their images were non-diagnostic. In the remaining 161 patients, there were 175 comparative patient images split into two groups: 81 had calf imaging and 94 had pedal imaging representing 405 and 198 imaged arteries, respectively. Weighted quadratic kappa/ICC values for intra- and inter-observer agreement were excellent (κ/ICC = 0.83 to 0.95) and had narrow confidence intervals in both groups. When comparing angiography and CEtUS, weighted quadratic κ/ICC agreement was moderate with acceptable confidence intervals in both groups (Calf κ/ICC = 0.54; Pedal κ/ICC = 0.53). Agreement decreased from popliteal to pedal vessels as diameter decreased. Agreement between CEtUS and digital subtraction angiography was best, and computed tomography angiography the weakest. CONCLUSION: CEtUS is a novel imaging modality with strong observer agreement that achieves clear peripheral and foot images without ionising radiation exposure or nephrotoxic X-ray contrast media. CEtUS enhances visualisation of runoff vessels, which may play a role in planning of limb salvage or targeted assessment.

An Ex Vivo Evaluation of Tomographic 3-D Ultrasound, B-Mode Ultrasound, CT And MR Imaging to Measure Artery Diameter, Length and Wall Volume.

Precise measurement of luminal diameter in arteries is important when planning interventional vascular procedures in patients. Measuring wall volume may be important in detecting early artery disease and in the assessment of treatments to prevent atherosclerosis. An ex vivo phantom using porcine arteries was used to evaluate the accuracy with which (i) B-mode ultrasound, (ii) 3-D tomographic ultrasound (tUS), (iii) computed tomography (CT) and (iv) magnetic resonance imaging (MRI) measured length, diameters and volume. The mean error in inner-to-inner diameter measurements by B mode, tUS, CT and MRI were 0.08 ± 0.26, -0.73 ± 0.96 mm, 0.09 ± 0.55 and 0.60 ± 1.01 mm, respectively. The mean error in outer-to-outer diameter measurements by B mode, tUS, CT and MRI were -1.33 ± 0.61, -1.03 ± 0.35, 0.02 ± 1.00 and -0.47 ± 1.32 mm, respectively. The mean error in volume measurements by B mode, tUS, CT and MRI were -0.54 ± 0.62, -0.06 ± 0.09, 0.01 ± 0.18 and -0.20 ± 0.32 cm3, respectively. Errors in length and diameters remain within clinically acceptable thresholds where MRI was the least accurate. tUS was the most accurate method of volume measurement.

Comparison of Contrast-Enhanced Tomographic 3-D Ultrasound Against Rotational Angiography Imaging Immediately After Endovascular Aneurysm Repair.

This proof of principle study assesses the utility of contrast-enhance ultrasound (CEUS) and contrast-enhanced tomographic 3-D ultrasound (CEtUS), as an intra-procedural imaging tool after endovascular-aneurysm repair (EVAR), compared with rotational angiography. A total of 20 consecutive patients undergoing infra-renal EVAR underwent immediate post-deployment rotational angiography, followed by CEUS and CEtUS scans. Outcomes were presence of endoleak, renal artery patency and endograft deformity. CEUS and CEtUS detected 12 endoleaks, 8 of which were not detected by rotational angiography. CEUS and CEtUS classify 7 or 8 type IIb endoleaks not detected by rotational angiography. CEUS/CEtUS could not identify 12 and 13 renal arteries, respectively, detected by rotational angiography. Rotational angiography and CEtUS both identified 1 endograft limb deformity, corrected immediately. CEUS and CEtUS are more sensitive to type II endoleak than rotational angiography, although there is a lower detection of renal arteries. CEUS or CEtUS has the utility for immediate post-EVAR endoleak detection where reduction of contrast agent is indicated.

Altered expression of dopaminergic cell fate regulating genes prior to manifestation of symptoms in a transgenic rat model of Huntington's disease.

Hyperactivity of the dopaminergic pathway is thought to contribute to clinical symptoms in the early stages of Huntington's disease (HD). It is suggested to be result of a reduced dopaminergic inhibition by degeneration of medium spiny neurons in the striatum. Previously, we have shown that the number of dopaminergic cells is increased in the dorsal raphe nucleus (DRN) of HD patients and transgenic HD (tgHD) rats during the manifestation phase of the disease; as well as in the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) of tgHD rats. To address whether these changes are secondary to neurodegeneration or take place in the pre-manifest phase of the disease, we examined the expression of genes controlling neuronal cell fate and genes that define dopaminergic cell phenotype. In the SNc-VTA of tgHD rats, Msx1 was upregulated, which correlated with an altered expression of transcription factors Zbtb16 and Tcf12. Zbtb16 was upregulated in the DRN and it was the only gene that showed a correlated expression in the tgHD rats between SNc-VTA and DRN. Zbtb16 may be a candidate for regionally tuning its cell populations, resulting in the increase in dopaminergic cells observed in our previous studies. Here, we demonstrated an altered expression of genes related to dopaminergic cell fate regulation in the brainstem of 6 months-old tgHD rats. This suggests that changes in dopaminergic system in HD precede the manifestation of clinical symptoms, contradicting the theory that hyperdopaminergic status in HD is a consequence of neurodegeneration in the striatum.

Intracerebroventricular Administration of a 2'-O-Methyl Phosphorothioate Antisense Oligonucleotide Results in Activation of the Innate Immune System in Mouse Brain.

Antisense oligonucleotides (AONs) are versatile molecules that can be used to modulate gene expression by binding to RNA. The therapeutic potential of AONs appears particularly high in the central nervous system, due to excellent distribution and uptake in brain cells, as well as good tolerability in clinical trials thus far. Nonetheless, immune stimulation in response to AON treatment in the brain remains a concern. For this reason we performed RNA sequencing analysis of brain tissue from mice treated intracerebroventricularly with phosphorothioate, 2'-O-methyl modified AONs. A significant upregulation of immune system associated genes was observed in brains of AON treated mice, with the striatum showing largest transcriptional changes. Strongest upregulation was seen for the antiviral enzyme 2'-5'-oligoadenylate synthase-like protein 2 (Oasl2) and Bone marrow stromal antigen 2 (Bst2). Histological analysis confirmed activation of microglia and astrocytes in striatum. The upregulation of immune system associated genes was detectable for at least 2 months after the last AON administration, consistent with a continuous immune response to the AON.

Transependymal Cerebrospinal Fluid Flow: Opportunity for Drug Delivery?

Drug delivery to the central nervous system (CNS) is complicated by the blood-brain barrier. As a result, many agents that are found to be potentially effective at their site of action cannot be sufficiently or effectively delivered to the CNS and therefore have been discarded and not developed further for clinical use, leaving many CNS diseases untreated. One way to overcome this obstacle is intracerebroventricular (ICV) delivery of the therapeutics directly to cerebrospinal fluid (CSF). Recent experimental and clinical findings reveal that CSF flows from the ventricles throughout the parenchyma towards the subarachnoid space also named minor CSF pathway, while earlier, it was suggested that only in pathological conditions such as hydrocephalus this form of CSF flow occurs. This transependymal flow of CSF provides a route to distribute ICV-infused drugs throughout the brain. More insight on transependymal CSF flow will direct more rational to ICV drug delivery and broaden its clinical indications in managing CNS diseases.

Learning Category-Specific Deformable 3D Models for Object Reconstruction.

We address the problem of fully automatic object localization and reconstruction from a single image. This is both a very challenging and very important problem which has, until recently, received limited attention due to difficulties in segmenting objects and predicting their poses. Here we leverage recent advances in learning convolutional networks for object detection and segmentation and introduce a complementary network for the task of camera viewpoint prediction. These predictors are very powerful, but still not perfect given the stringent requirements of shape reconstruction. Our main contribution is a new class of deformable 3D models that can be robustly fitted to images based on noisy pose and silhouette estimates computed upstream and that can be learned directly from 2D annotations available in object detection datasets. Our models capture top-down information about the main global modes of shape variation within a class providing a "low-frequency" shape. In order to capture fine instance-specific shape details, we fuse it with a high-frequency component recovered from shading cues. A comprehensive quantitative analysis and ablation study on the PASCAL 3D+ dataset validates the approach as we show fully automatic reconstructions on PASCAL VOC as well as large improvements on the task of viewpoint prediction.

Distribution and Penetration of Intracerebroventricularly Administered 2'OMePS Oligonucleotide in the Mouse Brain.

Antisense oligonucleotide (AON) therapy is emerging as a potential treatment strategy for neurodegenerative diseases, such as spinal muscular atrophy, Huntington's disease, and amyotrophic lateral sclerosis. AONs function at the cellular level by, for example, direct interference with the expression of gene products or the molecular activation of neuroprotective pathways. However, AON therapy faces a major obstacle limiting its clinical application for central nervous system (CNS) disorders: the blood-brain barrier. Systemic administration of AONs leads to rapid clearance and breakdown of its molecules in the periphery. One way to overcome this obstacle is intracerebroventricular (ICV) delivery of the therapeutics directly to cerebrospinal fluid (CSF). Given the particular molecular structure of oligonucleotides, the (pharmaco) kinetic and distribution pattern of these compounds in the brain are yet to be clarified. In this study, 2'OMePS oligonucleotide delivered through ICV into CSF reached the most key structures in the brain. The distribution of this oligonucleotide differed when comparing specific brain structures and cell groups. After 48 h post-infusion, the distribution of the oligonucleotide reached its maximum and was found intracellularly in many key brain structures. These findings help understanding the kinetic and distribution pattern of 2'OMePS oligonucleotide in the brain and will direct more rational and effective use of ICV drug delivery and unleash its full therapeutic potential in managing CNS diseases.

In vivo proof-of-concept of removal of the huntingtin caspase cleavage motif-encoding exon 12 approach in the YAC128 mouse model of Huntington's disease.

Huntington's disease (HD) is a progressive autosomal dominant disease, caused by a CAG repeat expansion in the HTT gene, resulting in an expanded polyglutamine stretch at the N-terminal of the huntingtin protein. An important event in HD pathogenesis appears to be the proteolysis of the mutant protein, which forms N-terminal huntingtin fragments. These fragments form insoluble aggregates and are found in nuclei and cytoplasm of affected neurons where they interfere with normal cell functioning. Important cleavage sites are encoded by exon 12 of HTT. A novel approach is Htt protein modification through exon skipping, which has recently been proven effective both in vitro and in vivo. Here we report proof-of-concept of AON 12.1 in vivo using the YAC128 mouse model of HD. Our results support and encourage future longitudinal studies exploring the therapeutic effects of sustained infusions in the YAC128 mouse model.

Lifting Object Detection Datasets into 3D.

While data has certainly taken the center stage in computer vision in recent years, it can still be difficult to obtain in certain scenarios. In particular, acquiring ground truth 3D shapes of objects pictured in 2D images remains a challenging feat and this has hampered progress in recognition-based object reconstruction from a single image. Here we propose to bypass previous solutions such as 3D scanning or manual design, that scale poorly, and instead populate object category detection datasets semi-automatically with dense, per-object 3D reconstructions, bootstrapped from:(i) class labels, (ii) ground truth figure-ground segmentations and (iii) a small set of keypoint annotations. Our proposed algorithm first estimates camera viewpoint using rigid structure-from-motion and then reconstructs object shapes by optimizing over visual hull proposals guided by loose within-class shape similarity assumptions. The visual hull sampling process attempts to intersect an object's projection cone with the cones of minimal subsets of other similar objects among those pictured from certain vantage points. We show that our method is able to produce convincing per-object 3D reconstructions and to accurately estimate cameras viewpoints on one of the most challenging existing object-category detection datasets, PASCAL VOC. We hope that our results will re-stimulate interest on joint object recognition and 3D reconstruction from a single image.

Free-Form Region Description with Second-Order Pooling.

Semantic segmentation and object detection are nowadays dominated by methods operating on regions obtained as a result of a bottom-up grouping process (segmentation) but use feature extractors developed for recognition on fixed-form (e.g. rectangular) patches, with full images as a special case. This is most likely suboptimal. In this paper we focus on feature extraction and description over free-form regions and study the relationship with their fixed-form counterparts. Our main contributions are novel pooling techniques that capture the second-order statistics of local descriptors inside such free-form regions. We introduce second-order generalizations of average and max-pooling that together with appropriate non-linearities, derived from the mathematical structure of their embedding space, lead to state-of-the-art recognition performance in semantic segmentation experiments without any type of local feature coding. In contrast, we show that codebook-based local feature coding is more important when feature extraction is constrained to operate over regions that include both foreground and large portions of the background, as typical in image classification settings, whereas for high-accuracy localization setups, second-order pooling over free-form regions produces results superior to those of the winning systems in the contemporary semantic segmentation challenges, with models that are much faster in both training and testing.

Coexistence of Gait Disturbances and Chorea in Experimental Huntington's Disease.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by an expanded CAG repeat. The clinical features are progressive motor dysfunction, cognitive deterioration, and psychiatric disturbances. Unpredictable choreic movements, among the most characteristic hallmarks, may contribute to gait disturbances and loss of balance in HD individuals. In this study, we aimed to investigate and characterize the gait abnormalities and choreic movements in a transgenic rat model of HD (tgHD). TgHD presents typical neuropathological, neurophysiological, and behavioral aspects mimicking some of the key features of human HD and is the only described experimental model for HD that exhibits choreiform movements. We used the Catwalk, with emphasis on static and dynamic gait parameters, to test the hypothesis that at symptomatic age (9 months) the dynamic measures of gait in HD are altered and coexist with choreiform movements. Our results showed that the dynamic parameters seem to be more affected than static parameters at this age in tgHD rats. The number of steps and step cycles and swing speed of the paws were increased in tgHD rat in comparison to wild-type controls. Our study demonstrates that gait abnormalities coexist with chorea rather than being caused by it. These symptoms may originate from distinct networks in the basal ganglia and downstream connections.

Mapping of the environmental contamination of Toxoplasma gondii by georeferencing isolates from chickens in an endemic area in Southeast Rio de Janeiro State, Brazil.

The environmental contamination of Toxoplasma gondii in an endemic area in Brazil was mapped by georeferencing isolates from chickens in farms in the Southeast of the state of Rio de Janeiro. Tissue samples obtained from 153 adult chickens were analyzed by the mouse bioassay for T. gondii infection. These animals were reared free-range on 51 farms in the municipalities of Rio Bonito and Maricá. The ArcGIS kernel density estimator based on the frequency of T. gondii-positive chickens was used to map the environmental contamination with this parasite. A questionnaire was applied to obtain data on the presence and management of cats and the type of water consumed. Of the farms studied, 64.7% were found to be located in areas of low to medium presence of T. gondii, 27.5% in areas with a high or very high contamination level and 7.8% in non-contaminated areas. Additionally, 70.6% kept cats, 66.7% were near water sources and 45.0% were in or near dense vegetation. Humans used untreated water for drinking on 41.2% of the farms, while all animals were given untreated water. The intensity of environmental T. gondii contamination was significantly higher on farms situated at a distance >500 m from water sources (P=0.007) and near (≤500 m) dense vegetation (P=0.003). Taken together, the results indicate a high probability of T. gondii infection of humans and animals living on the farms studied. The kernel density estimator obtained based on the frequency of chickens testing positive for T. gondii in the mouse bioassay was useful to map environmental contamination with this parasite.

Transgenic Rat Models of Huntington's Disease.

Several animal models for Huntington's disease (HD) have been created in order to investigate mechanisms of disease, and to evaluate the potency of novel therapies. Here, we describe the characteristics of the two transgenic rat models: transgenic rat model of HD (fragment model) and the Bacterial Artificial Chromosome HD model (full-length model). We discuss their genetic, behavioural, neuropathological and neurophysiological features.

A neuroanatomical analysis of the effects of a memory impairing dose of scopolamine in the rat brain using cytochrome c oxidase as principle marker.

Acetylcholine plays a role in mnemonic and attentional processes, but also in locomotor and anxiety-related behavior. Receptor blockage by scopolamine can therefore induce cognitive as well as motor deficits and increase anxiety levels. Here we show that scopolamine, at a dose that has previously been found to affect learning and memory performance (0.1 mg/kg i.p.), has a widespread effect on cytochrome c oxidase histochemistry in various regions of the rat brain. We found a down-regulation of cytochrome c oxidase in the nucleus basalis, in movement-related structures such as the primary motor cortex and the globus pallidus, memory-related structures such as the CA1 subfield of the hippocampus and perirhinal cortex and in anxiety-related structures like the amygdala, which also plays a role in memory. However choline acetyltransferase levels were only affected in the CA1 subfield of the hippocampus and both, choline acetyltransferase and c-Fos expression levels were decreased in the amygdala. These findings corroborate strong cognitive behavioral effects of this drug, but also suggest possible anxiety- and locomotor-related changes in subjects. Moreover, they present histochemical evidence that the effects of scopolamine are not ultimately restricted to cognitive parameters.