Wall shear rate and energy loss coefficient measures using conventional Doppler ultrasound do not predict carotid plaque progression.

Background: The rate of carotid plaque progression is believed to be related to blood flow hemodynamics and shear stress. Our objective was to determine if wall shear rate (WSR) and the energy loss coefficient (ELC) measured by Doppler ultrasound could predict atherosclerotic carotid disease progression. Patients and methods: Patients at a large tertiary center with an initial ultrasound between 2016 and 2018 with a significant carotid plaque were included if they had at least one 6 months follow-up comparative study. Stenosis progression was assessed according to the NASCET (The North American Symptomatic Carotid Endarterectomy Trial) percentage criterion. Results: The average annual progression rate for the 74 plaques included was 5.7% NASCET per year. We identified 18 plaques with ≥10% NASCET progression and 56 plaques without significant progression <10% NASCET. Among the plaques with progression, only four plaques had progression greater than 20% NASCET. Median WSR was 6266 s-1 [5813-8974] in plaques with progression and 6564 s-1 [5285-8766] in stable plaques (p=0.643). Median ELC was 3.86 m2 [2.78-5.53] in plaque with progression and 4.32 m2 [3.42-6.81] in stable plaques (p=0.296). Conclusions: Although it is a widely accepted hypothesis that shear stress and hemodynamics of the carotid bifurcation contribute to plaque progression, we found that WSR and ELC estimated by Doppler ultrasound do not reliably predict atherosclerotic plaque progression in the carotid artery. Other ultrasound modalities, such as 3D imaging, may be used to assess the influence of plaque geometry and hemodynamics in plaque progression.

Utility of unilateral versus bilateral venous reflux studies for venous insufficiency.

OBJECTIVE: Duplex ultrasonography is the reference standard for diagnosing chronic venous insufficiency. Bilateral venous reflux ultrasound studies are among the most time-consuming and physically demanding tests for vascular ultrasound technologists to perform. Furthermore, if a venous procedure is required, many insurance policies require that a diagnostic venous ultrasound scan for reflux must be performed within 1 year of the procedure. If the intervention is scheduled for >1 year after the ultrasound scan, the insurance company might require a repeat venous ultrasound scan before granting insurance authorization. Hence, ordering bilateral venous duplex ultrasound scans to evaluate for reflux when an intervention might only be performed on one limb within the year could be a waste of time and resources. The aim of the present study was to determine the utility of ordering bilateral vs unilateral studies to evaluate for reflux in patients with suspected chronic venous insufficiency and to determine whether a resource-saving potential exists for vascular laboratories through optimization of the process of ordering venous duplex ultrasound studies. METHODS: A retrospective review of all patients who had undergone bilateral lower extremity ultrasound scanning to evaluate for reflux from January 1, 2016 to December 31, 2016 at the Massachusetts General Hospital vascular laboratory was performed. The demographics, indications for ultrasound scanning, comorbidities, time required to perform the ultrasound study, and interval to intervention were documented. The data were analyzed using SPSS statistical software (IBM Corp, Armonk, NY). RESULTS: During the study period, 13,854 ultrasound studies had been performed in our vascular laboratory, of which 606 (4.4%) had been bilateral ultrasound scans for venous insufficiency. The time allotted for a bilateral study was 2 hours. Of the 606 studies evaluated, 152 (25.1%) showed no evidence of reflux, 284 (46.9%) showed bilateral lower extremity reflux, and 170 (28.1%) showed only venous insufficiency in one leg. Venous ablation, phlebectomy, and/or sclerotherapy were performed for 28.7% of the patients. However only 6.2% of patients had undergone venous procedures on both legs within 1 year after the ultrasound studies. Ablation was the most common procedure performed (54.6%), followed by phlebectomy (27.%) and sclerotherapy (17.9%). Overall, 94.7% of patients had not undergone a venous procedure on both legs within 1 year after the ultrasound studies and, hence, would have required a repeat duplex ultrasound scan to ensure insurance coverage for future procedures. CONCLUSIONS: Most bilateral ultrasound scans for venous insufficiency will not result in an intervention. Thus, most patients (95%) could have undergone a unilateral scan before the initial intervention instead of bilateral duplex ultrasound scanning.

Deep vein thrombosis protocol optimization to minimize healthcare worker exposure in coronavirus disease-2019.

OBJECTIVE: There are no societal ultrasound (US) guidelines detailing appropriate patient selection for deep vein thrombosis (DVT) imaging in patients with COVID-19, nor are there protocol recommendations aimed at decreasing exposure time for US technologists. We aimed to provide COVID-19-specific protocol optimization recommendations limiting US technologist exposure while optimizing patient selection. METHODS: A novel two-pronged algorithm was implemented to limit the DVT US studies on patients with COVID-19 prospectively, which included direct physician communication with the care team and a COVID-19-specific imaging protocol was instated to reduce US technologist exposure. To assess the pretest risk of DVT, the sensitivity and specificity of serum d-dimer in 500-unit increments from 500 to 8000 ng/mL and a receiver operating characteristic curve to assess performance of serum d-dimer in predicting DVT was generated. Rates of DVT, pulmonary embolism, and scan times were compared using t-test and Fisher's exact test (before and after implementation of the protocol). RESULTS: Direct physician communication resulted in cancellation or deferral of 72% of requested examinations in COVID-19-positive patients. A serum d-dimer of >4000 ng/mL yielded a sensitivity of 80% and a specificity of 70% (95% confidence interval, 0.54-0.86) for venous thromboembolism. Using the COVID-19-specific protocol, there was a significant (50%) decrease in the scan time (P < .0001) in comparison with the conventional protocol. CONCLUSIONS: A direct physician communication policy between imaging physician and referring physician resulted in deferral or cancellation of a majority of requested DVT US examinations. An abbreviated COVID-19-specific imaging protocol significantly decreased exposure time to the US technologist.