In vivo bistatic dual-aperture ultrasound imaging and elastography of the abdominal aorta.

Introduction: In this paper we introduce in vivo multi-aperture ultrasound imaging and elastography of the abdominal aorta. Monitoring of the geometry and growth of abdominal aortic aneurysms (AAA) is paramount for risk stratification and intervention planning. However, such an assessment is limited by the lateral lumen-wall contrast and resolution of conventional ultrasound. Here, an in vivo dual-aperture bistatic imaging approach is shown to improve abdominal ultrasound and strain imaging quality significantly. By scanning the aorta from different directions, a larger part of the vessel circumference can be visualized. Methods: In this first-in-man volunteer study, the performance of multi-aperture ultrasound imaging and elastography of the abdominal aortic wall was assessed in 20 healthy volunteers. Dual-probe acquisition was performed in which two curved array transducers were aligned in the same imaging plane. The transducers alternately transmit and both probes receive simultaneously on each transmit event, which allows for the reconstruction of four ultrasound signals. Automatic probe localization was achieved by optimizing the coherence of the trans-probe data, using a gradient descent algorithm. Speckle-tracking was performed on the four individual bistatic signals, after which the respective axial displacements were compounded and strains were calculated. Results: Using bistatic multi-aperture ultrasound imaging, the image quality of the ultrasound images, i.e., the angular coverage of the wall, was improved which enables accurate estimation of local motion dynamics and strain in the abdominal aortic wall. The motion tracking error was reduced from 1.3 mm ± 0.63 mm to 0.16 mm ± 0.076 mm, which increased the circumferential elastographic signal-to-noise ratio (SNRe) by 12.3 dB ± 8.3 dB on average, revealing more accurate and homogeneous strain estimates compared to single-perspective ultrasound. Conclusion: Multi-aperture ultrasound imaging and elastography is feasible in vivo and can provide the clinician with vital information about the anatomical and mechanical state of AAAs in the future.

Enabling strain imaging in realistic Eulerian ultrasound simulation methods.

Cardiovascular strain imaging is continually improving due to ongoing advances in ultrasound acquisition and data processing techniques. The phantoms used for validation of new methods are often burdensome to make and lack flexibility to vary mechanical and acoustic properties. Simulations of US imaging provide an alternative with the required flexibility and ground truth strain data. However, the current Lagrangian US strain imaging models cannot simulate heterogeneous speed of sound distributions and higher-order scattering, which limits the realism of the simulations. More realistic Eulerian modelling techniques exist but have so far not been used for strain imaging. In this research, a novel sampling scheme was developed based on a band-limited interpolation of the medium, which enables accurate strain simulation in Eulerian methods. The scheme was validated in k-Wave using various numerical phantoms and by a comparison with Field II. The method allows for simulations with a large range in strain values and was accurate with errors smaller than -60 dB. Furthermore, an excellent agreement with the Fourier theory of US scattering was found. The ability to perform simulations with heterogeneous speed of sound distributions was demonstrated using a pulsating artery model. The developed sampling scheme contributes to more realistic strain imaging simulations, in which the effect of heterogenous acoustic properties can be taken into account.

Performance of the BioIntegral Bovine Pericardial Graft in Vascular Infections: VASCular No-REact Graft Against INfection Study.

BACKGROUND: Vascular graft and endograft infections (VGEI) and native vessel infections (NVI) remain considerable challenges in vascular surgery, leading to high mortality and morbidity rates. Although in situ reconstruction is the preferred treatment, the material of choice is still a source of debate. Autologous veins are considered the first choice; however, xenografts may be an acceptable alternative. The performance of a biomodified bovine pericardial graft is assessed when implemented in an infected vascular area. METHODS: This is a prospective multicenter cohort study. Patients who underwent reconstruction for VGEI or NVI with a biomodified bovine pericardial bifurcated or straight tube graft were included from December 2017 until June 2021. The primary outcome measure was reinfection at mid-term follow-up. Secondary outcome measures included mortality, patency, and amputation rate. RESULTS: Thirty-four patients with vascular infections were included, of which 23 (68%) had an infected Dacron prosthesis after primary open repair and 8 (24%) had an infected endovascular graft. The remaining 3 (9%) had infected native vessels. At secondary repair, 3 (7%) patients had an in situ aortic tube reconstruction, 29 (66%) had an aortic bifurcated reconstruction, and 2 (5%) had an iliac-femoral reconstruction. At 1-year follow-up after the BioIntegral bovine pericardial graft reconstruction, the reinfection rate was 9%. The 1-year infection-related and procedure-related mortality rate was 16%. The occlusion rate was 6% and in total 3 patients underwent a lower limb amputation during the 1-year follow-up period. CONCLUSIONS: In situ reconstruction as treatment of (endo)graft and native vessel infections remains a challenge and reinfection looms as a potential consequence. In cases where time is of essence or when autologous venous repair is not feasible, a swift available solution is needed. The BioIntegral biomodified bovine pericardial graft may be an option as it shows reasonable results in terms of reinfection, in aortic tube and bifurcated grafts.

General Overview and Diagnostic (Imaging) Techniques for Neurogenic Thoracic Outlet Syndrome.

Thoracic outlet syndrome is an uncommon and controversial syndrome. Three different diagnoses can be made based on the compressed structure, arterial TOS, venous TOS, and neurogenic TOS, though combinations do exist as well. Diagnosing NTOS is difficult since no specific objective diagnostic modalities exist. This has resulted in a lot of controversy in recent decades. NTOS remains a clinical diagnosis and is mostly diagnosed based on the exclusion of an extensive list of differential diagnoses. To guide the diagnosis and treatment of TOS, a group of experts published the reporting standards for TOS in 2016. However, a consensus was not reached regarding a blueprint for a daily care pathway in this document. Therefore, we constructed a care pathway based on the reporting standards for both the diagnosis and treatment of NTOS patients. This care pathway includes a multidisciplinary approach in which different diagnostic tests and additional imaging techniques are combined to diagnose NTOS or guide patients in their treatment for differential diagnoses. The aim of the present work is to discuss and explain the diagnostic part of this care pathway.

An aberration correction approach for single and dual aperture ultrasound imaging of the abdomen.

Abdominal ultrasound image quality is hampered by phase aberration, that is mainly caused by the large speed-of-sound (SoS) differences between fat and muscle tissue in the abdominal wall. The mismatch between the assumed and actual SoS distribution introduces general blurring of the ultrasound images, and acoustic refraction can lead to geometric distortion of the imaged features. Large aperture imaging or dual-transducer imaging can improve abdominal imaging at deep locations by providing increased contrast and resolution. However, aberration effects for large aperture imaging can be even more severe, which limits its full potential. In this study, a model-based aberration correction method for arbitrary acquisition schemes is introduced for delay-and-sum (DAS) beamforming and its performance was analyzed for both single- and dual-transducer ultrasound imaging. The method employs aberration corrected wavefront arrival times, using manually assigned local SoS values. Two wavefront models were compared. The first model is based on a straight ray approximation, and the second model on the Eikonal equation, which is solved by a multi-stencils fast marching method. Their accuracy for abdominal imaging was evaluated in acoustic simulations and phantom experiments involving tissue-mimicking and porcine material with large SoS contrast (∼100 m/s). The lateral resolution was improved by up to 90% in simulations and up to 65% in experiments compared to standard DAS, in which the use of Eikonal beamforming generally outperformed straight ray beamforming. Moreover, geometric distortions were mitigated in multi-aperture imaging, leading to a reduction in position error of around 80%. A study on the sensitivity of the aberration correction to shape and SoS of aberrating layers was performed, showing that even with imperfect segmentations or SoS values, aberration correction still outperforms standard DAS.

A Statistical Shape Model of Infrarenal Aortic Necks in Patients With and Without Late Type Ia Endoleak After Endovascular Aneurysm Repair.

PURPOSE: Hostile aortic neck characteristics, including short length, severe suprarenal and infrarenal angulation, conicity, and large diameter, have been associated with increased risk for type Ia endoleak (T1aEL) after endovascular aneurysm repair (EVAR). This study investigates the mid-term discriminative ability of a statistical shape model (SSM) of the infrarenal aortic neck morphology compared with or in combination with conventional measurements in patients who developed T1aEL post-EVAR. MATERIALS AND METHODS: The dataset composed of EVAR patients who developed a T1aEL during follow-up and a control group without T1aEL. Principal component (PC) analysis was performed using a parametrization to create an SSM. Three logistic regression models were created. To discriminate between patients with and without T1aEL, sensitivity, specificity, and the area under the receiver operating characteristic (ROC) curve (AUC) were calculated. RESULTS: In total, 126 patients (84% male) were included. Median follow-up time in T1aEl group and control group was 52 (31, 78.5) and 51 (40, 62.5) months, respectively. Median follow-up time was not statistically different between the groups (p=0.72). A statistically significant difference between the median PC scores of the T1aEL and control groups was found for the first, eighth, and ninth PC. Sensitivity, specificity, and AUC values for the SSM-based versus the conventional measurements-based logistic regression models were 79%, 70%, and 0.82 versus 74%, 73%, and 0.85, respectively. The model of the SSM and conventional measurements combined resulted in sensitivity, specificity, and AUC of 81%, 81%, and 0.92. CONCLUSION: An SSM of the infrarenal aortic neck determines its 3-dimensional geometry. The SSM is a potential valuable tool for risk stratification and T1aEL prediction in EVAR. The SSM complements the conventional measurements of the individual preoperative infrarenal aortic neck geometry by increasing the predictive value for late type Ia endoleak after standard EVAR. CLINICAL IMPACT: A statistical shape model (SSM) determines the 3-dimensional geometry of the infrarenal aortic neck. The SSM complements the conventional measurements of the individual pre-operative infrarenal aortic neck geometry by increasing the predictive value for late type Ia endoleaks post-EVAR. The SSM is a potential valuable tool for risk stratification and late T1aEL prediction in EVAR and it is a first step toward implementation of a treatment planning support tool in daily clinical practice.

Spatiotemporal Registration of 3-D Multi-perspective Ultrasound Images of Abdominal Aortic Aneurysms.

Methods for patient-specific abdominal aortic aneurysm (AAA) progression monitoring and rupture risk assessment are widely investigated. Three-dimensional ultrasound can visualize the AAA's complex geometry and displacement fields. However, ultrasound has a limited field of view and low frame rate (i.e., 3-8 Hz). This article describes an approach to enhance the temporal resolution and the field of view. First, the frame rate was increased for each data set by sequencing multiple blood pulse cycles into one cycle. The sequencing method uses the original frame rate and the estimated pulse wave rate obtained from AAA distension curves. Second, the temporal registration was applied to multi-perspective acquisitions of the same AAA. Third, the field of view was increased through spatial registration and fusion using an image feature-based phase-only correlation method and a wavelet transform, respectively. Temporal sequencing was fully correct in aortic phantoms and was successful in 51 of 62 AAA patients, yielding a factor 5 frame rate increase. Spatial registration of proximal and distal ultrasound acquisitions was successful in 32 of 37 different AAA patients, based on the comparison between the fused ultrasound and computed tomography segmentation (95th percentile Haussdorf distances and similarity indices of 4.2 ± 1.7 mm and 0.92 ± 0.02 mm, respectively). Furthermore, the field of view was enlarged by 9%-49%.

Multiperspective Photoacoustic Imaging Using Spatially Diverse CMUTs.

Photoacoustic imaging (PAI) is a promising technique to assess different constituents in tissue. In PAI, the propagating waves are low-amplitude, isotropic, and broadband. A common approach in PAI is the use of a single linear or curved piezoelectric transducer array to perform both PA and ultrasound imaging. These systems provide freedom, agility, and versatility for performing imaging, but have limited field of view (FOV) and directivity that degrade the final image quality. Capacitive micromachined ultrasonic transducers (CMUTs) have a great potential to be used for PAI since they provide larger bandwidth and better cost efficiency. In this study, to improve the FOV, resolution, and contrast, we propose a multiperspective PAI (MP-PAI) approach using multiple CMUTs on a flexible array with shared channels. The designed array was used to perform MP-PAI in an in vitro experiment using a plaque mimicking phantom where the images were compounded both incoherently and coherently. The MP-PAI approach showed a significant improvement in overall image quality. Using only three CMUTs led to about 20% increase in generalized-contrast-to-noise ratio (gCNR), 2-dB improvement in peak signal-to-noise ratio (PSNR), and double the structural coverage in comparison to a single CMUT setup. In numerical studies, the MP-PAI was thoroughly evaluated for both the coherent and incoherent compounding methods. The assessments showed that the image quality further improved for increased number of transducers and angular coverage. For 15 transducers, the improvement for resolution and contrast could be up to three times the amount in a single-perspective image. Nonetheless, the most prominent improvement of MP-PAI was its ability to resolve the structural information of the phantoms.

Modeling toolchain for realistic simulation of photoacoustic data acquisition.

SIGNIFICANCE: Physics-based simulations of photoacoustic (PA) signals are used to validate new methods, to characterize PA setups and to generate training datasets for machine learning. However, a thoroughly validated PA simulation toolchain that can simulate realistic images is still lacking. AIM: A quantitative toolchain was developed to model PA image acquisition in complex tissues, by simulating both the optical fluence and the acoustic wave propagation. APPROACH: Sampling techniques were developed to decrease artifacts in acoustic simulations. The performance of the simulations was analyzed by measuring the point spread function (PSF) and using a rotatable three-channel phantom, filled with cholesterol, a human carotid plaque sample, and porcine blood. Ex vivo human plaque samples were simulated to validate the methods in more complex tissues. RESULTS: The sampling techniques could enhance the quality of the simulated PA images effectively. The resolution and intensity of the PSF in the turbid medium matched the experimental data well. Overall, the appearance, signal-to-noise ratio and speckle of the images could be simulated accurately. CONCLUSIONS: A PA toolchain was developed and validated, and the results indicate a great potential of PA simulations in more complex and heterogeneous media.

Editor's Choice - Endurant Stent Graft in Patients with Challenging Neck Anatomy "One Step Outside Instructions for Use": Early and Midterm Results from the EAGLE Registry.

OBJECTIVE: The aim of the Endurant for Challenging Anatomy: Global Experience (EAGLE) registry is to evaluate prospectively the technical and clinical success rate of a stentgraft used in patients with challenging neck anatomy outside the instructions for use (IFU) but within objective anatomical limits. METHODS: This was a prospective, international, multicentre, observational study. From 1 February 2012 to 1 September 2017, patients with an abdominal aortic aneurysm with a challenging infrarenal neck that were deemed suitable for endovascular aneurysm repair were included prospectively at 23 European centres. Patients were distributed by anatomy into three groups: short neck (SN; infrarenal neck 5 - 10 mm in combination with suprarenal angulation [α] ≤ 45° and infrarenal angulation [ß] ≤ 60°); medium neck (MN; infrarenal neck 10 - 15 mm with α ≤ 60° and ß 60° - 75° or α 45°- 60° and ß ≤ 75°; and long angulated neck (LN; infrarenal neck ≥ 15 mm with α ≤ 75° and ß 75°- 90° or α 60°- 75° and ß ≤ 90°. All computed tomography scans were reviewed by an independent core laboratory. Primary outcomes were technical and clinical success. Secondary endpoints were peri-operative major adverse events, all cause mortality, aneurysm related mortality, endoleaks, migration, and secondary intervention. RESULTS: One hundred and fifty patients (81.3% male) were included (SN = 55, MN = 16, LN = 79). The median follow up was 36 ± 12.6 months. In the overall cohort, the technical success rate was 93.3%. Estimated freedom from aneurysm related death was 97.3% at three years. Freedom from secondary interventions was 84.7% at three years. Estimated clinical success was 96.0%, 90.8%, and 83.2% at 30 days, one year, and three years, respectively. Estimated freedom from all cause mortality, late type IA endoleak, and migration at three years was 75.1%, 93.7%, and 99.3%, respectively. CONCLUSION: The early and midterm results of the EAGLE registry show that endovascular repair with the Endurant stentgraft in selected patients with challenging infrarenal neck anatomy yields results in line with large "real world" registries. Long term results are awaited for more definitive conclusions.

Surgery Versus Continued Conservative Treatment for Neurogenic Thoracic Outlet Syndrome: the First Randomised Clinical Trial (STOPNTOS Trial).

OBJECTIVE: Neurogenic thoracic outlet syndrome (NTOS) is one of the most controversial clinical entities in medicine. Several major case series have shown promising results of surgery; however, solid scientific evidence is lacking. The aim of this trial was to objectify the effect of thoracic outlet decompression (TOD). METHODS: A single centre (high volume, tertiary TOS centre), non-blinded, randomised controlled trial was conducted with parallel group design. Patients with a diagnosis of NTOS refractory to conservative therapy were randomised to one of two intervention arms, receiving either a transaxillary thoracic outlet decompression (TA-TOD) or continued conservative treatment. After three months, the conservative treated group was also offered a TA-TOD. The primary outcome was change in Disability of the Arm, Shoulder and Hand (DASH) questionnaire score. Secondary outcomes were changes in Cervical Brachial Symptoms Questionnaire (CBSQ), TOS disability scale, and quality of life scores. Outcomes were assessed at baseline, three, six, and 12 months after inclusion. RESULTS: Fifty patients were enrolled in this trial: 25 in the TA-TOD group and 25 in the continued conservative treatment group. Follow up was completed in 24 and 22 patients, respectively. At three months, there was a statistically significant difference in DASH scores (TA-TOD: mean 45.15, 95% confidence interval [CI] 38.08 - 52.21; conservative treatment: mean 64.92, 95% CI 57.54 - 72.30; p < .001). All patients in the conservative treatment group applied for surgery three months after randomisation. After surgery of the conservative treatment group, there was no statistically significant difference between the groups for all primary and secondary outcome measures. CONCLUSIONS: TA-TOD for NTOS is effective in patients who do not respond to conservative treatment. Trial register number: NL63986.100.17.

Reliability and validity of the elevated arm stress test in the diagnosis of neurogenic thoracic outlet syndrome.

OBJECTIVES: The objective of this retrospective analysis of prospectively collected data was to assess the test-retest reliability and validity of the elevated arm stress test (EAST) as measured by the duration in a cohort of patients with suspected neurogenic thoracic outlet syndrome (NTOS). METHODS: Patients evaluated for NTOS between January 2017 and September 2018 were identified. Test-retest reliability by the intraclass correlation coefficient was determined for duration of the EAST. For the validity analysis, patients were classified in a proven NTOS group or a symptomatic control group without NTOS using the Society for Vascular Surgery reporting standards and the outcome of thoracic outlet decompression surgery. A receiver operating characteristic curve was made for the duration of EAST. The area under the curve, and positive and negative predictive values were calculated for the EAST. RESULTS: In total, 428 patients with suspected NTOS were retrospectively analyzed. Of these patients, 61 were excluded because no EAST data was available. Another 101 patients were excluded because of inconclusive reporting standards, arterial or venous TOS, or because thoracic outlet decompression surgery was not performed or had a negative result. The validity analysis in the remaining 266 patients showed an area under the curve for the duration of the EAST of 0.62 (95% confidence interval, 0.55-0.69). The positive predictive value of the duration ranged between 65% and 66%, and the negative predictive value between 53% and 58%. For the test-retest reliability analysis, 118 patients were excluded because they performed only one measurement in a 100-day time period. Analysis in the remaining 148 patients showed an intraclass correlation coefficient value of 0.65 (95% confidence interval, 0.55-0.74) for duration. CONCLUSIONS: The EAST measured by the duration showed a moderate test-retest reliability, but the discriminative value was low in the diagnosis of NTOS. The outcome of the EAST measured by the duration should be used with caution.

Corrigendum: Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-Stress.

[This corrects the article DOI: 10.3389/fphys.2021.717593.].

Reliability and validity of the standardized elevated arm stress test in the diagnosis of neurogenic thoracic outlet syndrome.

OBJECTIVE: We developed a standardized elevated arm stress test (sEAST) meter to standardize patients' posture and measure additional grip and fatigue parameters. In the present prospective cohort study, we aimed to determine the reliability and validity of the sEAST in the diagnosis of neurogenic thoracic outlet syndrome (NTOS). METHODS: Patients evaluated for NTOS between October 2018 and February 2020 were included and performed the sEAST. The patients were classified into a proven NTOS group or a symptomatic control group using the reporting standards for NTOS and the outcome of thoracic outlet decompression surgery. Healthy persons were recruited as an asymptomatic control group. The test-retest reliability, area under the receiver operating characteristic curve, and positive and negative predictive values were calculated for each sEAST parameter. RESULTS: A total of 426 patients with suspected NTOS and 147 healthy controls had performed the sEAST. The validity analysis was performed with data from 111 patients with proven NTOS, 94 symptomatic controls, and 147 asymptomatic controls. The reporting standards were inconclusive for 116 patients; 77 patients had been excluded because thoracic outlet decompression surgery had not been performed or was unsuccessful, and 28 because they had arterial or venous thoracic outlet syndrome. The area under the receiver operating characteristic curve for the proven NTOS group compared with the asymptomatic control and symptomatic control groups ranged from 0.59 to 0.77 and 0.54 to 0.63, respectively. The positive predictive value ranged from 46% to 65% and the negative predictive value from 51% to 66%. The test-retest reliability analysis for 80 patients with multiple sEAST measurements showed moderate to good (0.52-0.87) intraclass correlation coefficient values for the duration and grip strength parameters. However, the grip fatigue parameters demonstrated poor (0.46-0.16) intraclass correlation coefficient values. CONCLUSIONS: The sEAST showed good test-retest reliability for the duration and grip strength parameters. However, the discriminative value of all sEAST parameters was low for NTOS diagnostics. The good test-retest reliability of the sEAST parameters indicates that they could be valuable outcome measures for comparison in a diagnostic care pathway.

Redo surgery for neurogenic thoracic outlet syndrome is useful.

OBJECTIVES: Surgery for neurogenic thoracic outlet syndrome (NTOS) has shown good outcome in numerous case series. However, 5% to 30% of patients will have persistent or recurrent symptoms, caused by incomplete first rib resection, reattachment of residual scalene muscle, fibrous scarring around the brachial plexus, or a wrong NTOS diagnosis. In patients with a sound diagnosis of recurrent or persisting NTOS, not responding to conservative measures, a secondary procedure can be considered. We report the results of redo thoracic outlet decompression surgery through the supraclavicular approach (SC-REDO-TOD) for persistent or recurrent NTOS. METHODS: A retrospective review of a prospective database was performed. Every patient referred from September 2016 until January 2020 was eligible for inclusion. In an SC-REDO-TOD, we perform complete (cartilage-cartilage) resection of the first rib, any bony and fibrous anomalies, complete anterior and middle scalenectomy, and complete neurolysis of the brachial plexus (complete anatomical decompression of the brachial plexus). Clinical outcomes were assessed by questionnaires including the Disability of Arm, Shoulder and Hand (DASH), Cervico-Brachial Symptoms Questionnaire (CBSQ), and TOS (thoracic outlet syndrome) Disability scale. RESULTS: In total, 45 patients had a SC-REDO-TOD. The median duration of hospital admission after SC-REDO-TOD was 1.41 days (interquartile range, 1.00 day). In total, 30 (66.66%) of 45 patients had recurrent NTOS, and 15 (33.33%) of 45 patients had persisting NTOS. Postoperative complications were seen in eight patients (18.18%). One patient had postoperative complications with permanent impairment (Horner syndrome). Seven patients had postoperative complications with full recovery (three patients had a chylous leakage that was treated with a median-chain triglycerides diet for 6 weeks, three patients had transient phrenic nerve palsy with full recovery <6 weeks, and one patient had a discrete Horner syndrome that resolved in 6 weeks). The median time of follow-up was 19.50 months (interquartile range, 14.00 months) and the response rate to the questionnaires was 91.11% at 6 months and 64.44% at 12 months. We found a positive and statistically significant difference for DASH score, CBSQ score, and TOS Disability Scale score comparing scores for all patients. (DASH score: P < .001; CBSQ score: P < .001; TOS Disability Scale: P < .001). Patients with first rib remnants showed a significant better response (lower DASH, CBSQ and TOS Disability Scale scores) compared with patients without first rib remnants (DASH score: P = .004; CBSQ score: P ≤ .014; TOS Disability Scale: P = .009). CONCLUSIONS: SC-REDO-TOD after a previous NTOS surgery shows good results with a low risk of permanent impairment. Patients with NTOS with first rib remnants after primary surgery seem to benefit the most from SC-REDO-TOD surgery.

Thoracic outlet decompression surgery for Gilliatt-Sumner hand as a presentation of neurogenic thoracic outlet syndrome.

BACKGROUND: Chronic compression of the inferior trunk of the brachial plexus can result in severe pain and progressive atrophy and weakness of the musculature of the forearm and hand, known as Gilliatt-Sumner hand (GSH). The objective of treatment for these patients is to stop further atrophy and pain. Restoration of motor function has been thought to be seldom achieved. The aim of the present contemporary case series was to describe the diagnosis, treatment, and outcomes of surgery for GSH. METHODS: All patients referred between January 2017 and May 2021 with visible signs of a GSH were included. Visible GSH signs were defined as muscle atrophy of the abductor digiti minimi, abductor pollicis brevis, and/or interosseous musculature. All the patients had undergone additional electrodiagnostic (ED) assessments and high-resolution ultrasound (HRUS) studies. All the patients with a diagnosis of GSH had undergone thoracic outlet decompression (TOD) surgery using a transaxillary or supraclavicular approach. The outcomes were measured using the thoracic outlet syndrome disability scale, cervical brachial symptom questionnaire, and disability of the arm, shoulder, and hand scale scores and patient-reported outcomes of motor function, measured using a numerical rating scale (NRS). The standardized elevated arm stress test (sEAST) was used to assess the patients' motor function before and after TOD surgery. RESULTS: A total of 20 patients had been referred to our center with visible signs of a GSH. The clinical examination showed atrophy of the abductor digiti minimi, abductor pollicis brevis, and interosseous musculature in all 20 patients. The ED assessments showed plexopathy of the lower brachial plexus in all the patients. HRUS showed an indented inferior trunk of the brachial plexus (so-called wedge-sickle sign) in 18 patients (90%). Of the 20 patients, 17 had undergone TOD surgery (15 transaxillary TOD and 2 supraclavicular TOD). Three patients had refrained from surgery. The median follow-up interval was 15.0 months (interquartile range, 14.0 months). The thoracic outlet syndrome disability scale score had improved significantly (preoperatively: mean, 6.31; 95% confidence interval [CI], 5.49-7.13; postoperatively: mean, 4.25; 95% CI, 2.80-5.70; P = .026). The same improvement was seen for the cervical brachial symptom questionnaire scores (preoperatively: mean, 77.75; 95% CI, 66.63-88.87; postoperatively: mean, 42.65; 95% CI, 24.77-60.77; P = .001) and disability of the arm, shoulder, and hand scale scores (preoperatively: mean, 59.13; 95% CI, 51.49-66.77; postoperatively: mean, 40.96; 95% CI, 24.41-57.51; P = .032). The NRS score for muscle weakness and sEAST score showed no statistically significant differences before and after TOD for the whole group (mean preoperative NRS score for muscle weakness, 6.22; 95% CI, 4.31-8.14; mean postoperative NRS score for muscle weakness, 5.11; 95% CI, 3.25-6.97; P = .269). However, four patients (23.52%) had reported a ≥50% decrease in the NRS score for muscle weakness and a minimum increase of 20% in the total and average force using the sEAST. The NRS for numbness showed a statistically significant decrease for the whole group (preoperatively: mean, 5.67; 95% CI, 4.18-7.16; postoperatively: mean, 3.33; 95% CI, 1.37-5.29; P = .029). CONCLUSIONS: A combination of physical examination, ED assessments, and HRUS studies can differentiate GSH in the differential diagnosis. HRUS appears to have an advantage over ED studies in confirming GSH by visualization of compression of the brachial plexus. TOD surgery will stop the progressive muscle atrophy and significantly reduce neurogenic thoracic outlet syndrome complaints, and, in some patients, motor function will recover.

Local and global distensibility assessment of abdominal aortic aneurysms in vivo from probe tracked 2D ultrasound images.

Rupture risk estimation of abdominal aortic aneurysm (AAA) patients is currently based on the maximum diameter of the AAA. Mechanical properties that characterize the mechanical state of the vessel may serve as a better rupture risk predictor. Non-electrocardiogram-gated (non-ECG-gated) freehand 2D ultrasound imaging is a fast approach from which a reconstructed volumetric image of the aorta can be obtained. From this 3D image, the geometry, volume, and maximum diameter can be obtained. The distortion caused by the pulsatility of the vessel during the acquisition is usually neglected, while it could provide additional quantitative parameters of the vessel wall. In this study, a framework was established to semi-automatically segment probe tracked images of healthy aortas (N = 10) and AAAs (N = 16), after which patient-specific geometries of the vessel at end diastole (ED), end systole (ES), and at the mean arterial pressure (MAP) state were automatically assessed using heart frequency detection and envelope detection. After registration AAA geometries were compared to the gold standard computed tomography (CT). Local mechanical properties, i.e., compliance, distensibility and circumferential strain, were computed from the assessed ED and ES geometries for healthy aortas and AAAs, and by using measured brachial pulse pressure values. Globally, volume, compliance, and distensibility were computed. Geometries were in good agreement with CT geometries, with a median similarity index and interquartile range of 0.91 [0.90-0.92] and mean Hausdorff distance and interquartile range of 4.7 [3.9-5.6] mm. As expected, distensibility (Healthy aortas: 80 ± 15·10-3 kPa-1; AAAs: 29 ± 9.6·10-3 kPa-1) and circumferential strain (Healthy aortas: 0.25 ± 0.03; AAAs: 0.15 ± 0.03) were larger in healthy vessels compared to AAAs. Circumferential strain values were in accordance with literature. Global healthy aorta distensibility was significantly different from AAAs, as was demonstrated with a Wilcoxon test (p-value = 2·10-5). Improved image contrast and lateral resolution could help to further improve segmentation to improve mechanical characterization. The presented work has demonstrated how besides accurate geometrical assessment freehand 2D ultrasound imaging is a promising tool for additional mechanical property characterization of AAAs.

Duplex Ultrasound Studies Are Neither Necessary or Sufficient for the Diagnosis of Neurogenic Thoracic Outlet Syndrome.

BACKGROUND: Duplex ultrasound (DU) is used in the diagnosis of neurogenic thoracic outlet syndrome (NTOS) to measure compression of the subclavian artery (SCA) which is thought to strengthen the NTOS diagnosis. However, the value of DU in NTOS remains unclear. METHODS: A retrospective review of a prospectively acquired database from the TOS center of the Catharina Hospital Eindhoven was performed of patients referred between January 2017 and December 2019. Only "proven NTOS" patients, defined as a successful response to thoracic outlet decompression (TOD) surgery based on patient-reported outcomes (NRS pain scale, CBSQ and DASH score) were included to exclude wrongfully diagnosed NTOS patient. The presence of vascular symptoms (defined as discoloration, edema or temperature changes of the hand or fingers), results of provocative maneuvers, and outcome of DU was used for analysis. To assess the link between vascular symptoms and compression on DU, a chi-squared test was performed. Further, we looked for a correlation between vascular symptoms, compression on DU and clinical outcome using a repeated measures analysis of variance (ANOVA). RESULTS: Vascular symptoms were seen in 49 of 133 patients (36.8%). In total, 51 of 133 patients (38.3%) had at least 50% variation in SCA peak systolic velocity (PSV) during DU at the level of SCA stenosis. SCA occlusion was seen in 11 patients (8.3%) during provocative maneuvers. The presence of clinical "arterial symptoms" was not significantly correlated with vascular laboratory findings, neither for alterations in PSV during DU (P = 0.245) nor for positional SCA occlusion (P = 0.540). No statistically significant correlations between the degree of SCA stenosis and postoperative outcomes, as measured with the DASH, CBSQ, or NRS scale for pain were found (P = 0.787). CONCLUSIONS: The role of DU in the work-up of NTOS in patients with vascular complaints is questionable. Changes in flow velocities are seen in NTOS patients and do not correlate with "vascular symptoms" or clinical outcome.

Multiperspective Bistatic Ultrasound Imaging and Elastography of the Ex Vivo Abdominal Aorta.

Knowledge of aneurysm geometry and local mechanical wall parameters using ultrasound (US) can contribute to a better prediction of rupture risk in abdominal aortic aneurysms (AAAs). However, aortic strain imaging using conventional US is limited by the lateral lumen-wall contrast and resolution. In this study, ultrafast multiperspective bistatic (MP BS) imaging is used to improve aortic US, in which two curved array transducers receive simultaneously on each transmit event. The advantage of such bistatic US imaging on both image quality and strain estimations was investigated by comparing it to single-perspective monostatic (SP MS) and MP monostatic (MP MS) imaging, i.e., alternately transmitting and receiving with either transducer. Experimental strain imaging was performed in US simulations and in an experimental study on porcine aortas. Different compounding strategies were tested to retrieve the most useful information from each received US signal. Finally, apart from the conventional sector grid in curved array US imaging, a polar grid with respect to the vessel's local coordinate system is introduced. This new reconstruction method demonstrated improved displacement estimations in aortic US. The US simulations showed increased strain estimation accuracy using MP BS imaging bistatic imaging compared to MP MS imaging, with a decrease in the average relative error between 41% and 84% in vessel wall regions between transducers. In the experimental results, the mean image contrast-to-noise ratio was improved by up to 8 dB in the vessel wall regions between transducers. This resulted in an increased mean elastographic signal-to-noise ratio by about 15 dB in radial strain and 6 dB in circumferential strain.

Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-stress.

Currently, the prediction of rupture risk in abdominal aortic aneurysms (AAAs) solely relies on maximum diameter. However, wall mechanics and hemodynamics have shown to provide better risk indicators. Patient-specific fluid-structure interaction (FSI) simulations based on a non-invasive image modality are required to establish a patient-specific risk indicator. In this study, a robust framework to execute FSI simulations based on time-resolved three-dimensional ultrasound (3D+t US) data was obtained and employed on a data set of 30 AAA patients. Furthermore, the effect of including a pre-stress estimation (PSE) to obtain the stresses present in the measured geometry was evaluated. The established workflow uses the patient-specific 3D+t US-based segmentation and brachial blood pressure as input to generate meshes and boundary conditions for the FSI simulations. The 3D+t US-based FSI framework was successfully employed on an extensive set of AAA patient data. Omitting the pre-stress results in increased displacements, decreased wall stresses, and deviating time-averaged wall shear stress and oscillatory shear index patterns. These results underline the importance of incorporating pre-stress in FSI simulations. After validation, the presented framework provides an important tool for personalized modeling and longitudinal studies on AAA growth and rupture risk.