Ultrasound Could Improve Vascular Disease Detection.

By AuntMinnie.com staff writers

August 21, 2018 -- Ultrasound could improve the early detection of vascular disease, perhaps even before patients develop symptoms, according to a preclinical study published August 7 in the journal Ultrasound.

Researchers from the University of Leicester in the U.K. used ultrasound and semiautomatic image processing in mice to investigate the progression of abdominal aortic aneurysm and atherosclerosis. Ultrasound is used for a wide range of diseases and offers real-time information on the ability of arteries to expand and contract.

First author Dr. Justyna Janus and colleagues found changes in the ability of the mice's blood vessels to pulsate as the disease state worsened, suggesting that ultrasound could help in the early detection of reduced vascular function.

"Our study ... suggests that the ultrasound methods we employed can detect early changes in blood vessel function that can serve as a marker for detection of disease," co-author Dr. Mike Kelly said in a statement released by the university.

Ultrasound Imaging Gauges Muscle Tightness after Stroke

By Kate Madden Yee, AuntMinnie.com staff writer

August 22, 2018 -- Ultrasound strain imaging can be an effective tool for assessing poststroke muscle spasticity or tightness, a condition that affect two-thirds of stroke survivors, according to a study published in the August issue of the Journal of Ultrasound in Medicine.

The effects of spasticity on muscle after a stroke can include contractures, limited range of joint motion, and pain. Spasticity manifests most often around the elbow, the wrist, and the ankle, but it can also affect other parts of the body, including the biceps brachii muscle, or elbow flexors.

There hasn't been an effective way to measure spasticity to determine which interventions are best for patients after a stroke, wrote a team led by Dr. Jing Gao of Weill Cornell Medicine in New York City.

"To date, this process [of measuring spasticity] remains challenging because of the lack of a reference standard. ... It would be ideal to have a noninvasive imaging technique to quantify the mechanical properties and dynamic movement of spastic muscle to assist clinicians in the diagnosis of spasticity, monitoring of disease progression, and evaluation of treatment response in stroke rehabilitation," the group wrote.

Ultrasound strain imaging has been shown to be useful for assessing the stiffness of skeletal muscle, but little is known about using the technique to assess skeletal muscle dynamic motion. Gao and colleagues sought to evaluate the feasibility of strain imaging for assessing spasticity in the biceps of stroke survivors (J Ultrasound Med, August 2018, Vol. 37:8, pp. 2043-2052).

The study included eight healthy volunteers and seven stroke survivors recruited between February and July 2017; the investigators gathered ultrasound strain imaging data from all participants.

They found a significant increase in muscle stiffness, represented by a decrease in muscle axial strain in the spastic biceps brachii muscles compared with the nonspastic muscles. The researchers also found decreased lengthening and shortening capability (i.e., longitudinal strain ratio) and tissue velocity in the spastic muscles versus the nonspastic ones.

Ultrasound strain imaging measures for biceps brachii muscle
Measure	Nonspastic biceps	Spastic biceps
Axial strain ratio (90°)	4.87	3.13
Axial strain ratio (0°)	4.02	2.65
Longitudinal strain ratio (90° to 0°)	5.79	3.12
Longitudinal strain ratio (0° to 90°)	6.56	3.25
Tissue velocity (90° to 0°)	2.16	1.33
Tissue velocity (0° to 90°)	-2.09	-0.95

The study suggests that ultrasound strain imaging could help clinicians better assess a patient's poststroke spasticity and perhaps better manage the condition, Gao and colleagues concluded.

"Ultrasound strain imaging is a useful imaging tool for determining increased stiffness and decreased dynamic displacement in spastic biceps brachii muscles by assessing the axial strain, longitudinal strain, and tissue velocity of the muscle," they wrote. "These noninvasive strain imaging markers may have potential in improving the point-of-care management of chronic poststroke spasticity."

SIÊU ÂM CÁC ĐỘNG MẠCH CẢNH

https://pubs.rsna.org/doi/10.1148/rg.25604501

Conclusions

Carotid US offers a noninvasive evaluation of the extracranial neck portions of the carotid and vertebral arteries for atherosclerotic disease. Standardized technical parameters, scanning methods, Doppler analysis, and interpretation enhance the accuracy and reproducibility of the results.

Abstract

Ultrasonography (US) of the carotid arteries is a common imaging study performed for diagnosis of carotid artery disease. In the United States, carotid US may be the only diagnostic imaging modality performed before carotid endarterectomy. Therefore, the information obtained with carotid US must be reliable and reproducible. Technical parameters that can affect the accuracy of carotid US results include the Doppler angle, sample volume box, color Doppler sampling window, color velocity scale, and color gain. Important factors in diagnosis of atherosclerotic disease of the extracranial carotid arteries are the intima-media thickness, plaque morphology, criteria for grading stenosis, limiting factors such as the presence of dissection or cardiac abnormalities, distinction between near occlusion and total occlusion, and the presence of a subclavian steal. Challenges to the consistency of carotid US results may include lack of a standard protocol, poor Doppler technique, inexperience in interpretation of hemodynamic changes reflected in the Doppler waveform, artifacts, and physical challenges. Hindrances in the classification of problematic carotid artery stenoses may be overcome by following a standard protocol and optimizing scanning techniques and Doppler settings.

© RSNA, 2005

Deep Vein Thrombosis [D V T]

Deep vein thrombosis

Dr Yuranga Weerakkody◉ and A.Prof Frank Gaillard◉◈ et al.

https://radiopaedia.org/articles/deep-vein-thrombosis

The term deep vein thrombosis (DVT) is practically a synonym for those that occur in the lower limbs. However, it can also be used for those that occur in the upper limbs and neck veins. Other types of venous thrombosis, such as intra-abdominal and intracranial, are discussed in separate articles.

The majority of deep venous thromboses occur in the lower extremities and begin in the soleal veins of the calf. Doppler compression sonography is the imaging modality of choice.

Features include:

• non-compressible venous segment
• increased venous diameter: acute thrombus
• decreased venous diameter: chronic thrombus
• loss of phasic flow on Valsalva manoeuvre
• absent colour flow: if completely occlusive
• increased flow in superficial veins
• lack of flow augmentation with calf squeeze
• anechoic thrombus: acute thrombus
• echogenic thrombus: chronic thrombus

  Key Points

© Springer International Publishing AG 2018

A. Creditt et al., Clinical Ultrasound,  

https://doi.org/10.1007/978-3-319-68634-9_14

•  Using point-of-care ultrasound to evaluate patients  in the emergency department has been shown to decrease length of stay when compared with patients who receive studies performed by the radiology department [4].

•  Classically the femoral vein lies medial to the femoral artery; however, a common anatomic variant is for the femoral artery to travel anterior to the femoral vein [1].

•  Veins collapse easily with pressure. If you cannot visualize a vein, apply less pressure with the transducer.

•  Apply direct and even pressure over the vein to assess its compressibility:

  – A false-positive DVT can be diagnosed if uneven pressure is applied, therefore, resulting in an inability to completely compress the vein.

  – This can also occur with patients who have larger body habitus as it is harder to apply direct and even pressure.

•  Noncompressible veins can also be seen with chronic DVTs:

  – When a DVT re-cannulates, it can cause the walls of the vein to become stiffer and less responsive to compression.

•  Do not rely on visualization of the clot for diagnosis of a DVT as the appearance changes with maturation:

  – If a vein does not completely compress, this is diagnostic of a DVT even if no thrombus is visualized within the lumen [2].

•  While a chronic DVT may appear more echogenic with thickened irregular walls, these findings may not be present and it may not be possible to distinguish an acute from a chronic thrombus [3].

•  Point-of-care ultrasound for DVT without the use of color Doppler can be less reliable in patients with recurrent DVT:

  – Approximately 50% of ultrasounds can be abnormal 1 year after initial diagnosis of a DVT [5].

Doppler Ultrasonography of the Lower Extremity Arteries

https://www.e-ultrasonography.org/upload/usg-16054.pdf

Doppler ultrasonography of the lower extremity arteries is a valuable technique, although it is less frequently indicated for peripheral arterial disease than for deep vein thrombosis or varicose veins. Ultrasonography can diagnose stenosis through the direct visualization of plaques and through the analysis of the Doppler waveforms in stenotic and poststenotic arteries. To perform Doppler ultrasonography of the lower extremity arteries, the operator should be familiar with the arterial anatomy of the lower extremities, basic scanning techniques, and the parameters used in color and pulsed-wave Doppler ultrasonography.

Doppler US is the only noninvasive technique that does not require contrast enhancement, preparation of the patient before the study, or radiation exposure [1,2]. Doppler US is a good method for screening and follow-up, as well as for the definitive diagnosis of peripheral arterial disease [3-7]. Color Doppler US can easily identify arteries by finding round objects with regular pulsation and can be used to detect stenotic or occluded segments [4,8]. Pulsed-wave Doppler US can show the exact flow velocity of each arterial segment and determine the degree of severity of the stenosis based on an analysis of the pulsed-wave Doppler spectral waveform [9]. Knowledge of the ultrasonographic anatomy of the lower extremity arteries and the corresponding anatomical landmarks is essential for performing Doppler US. In this article, we review the basic scanning techniques of color and pulsed-wave Doppler US for the lower extremity arteries and the spectral analysis of normal and stenotic arteries on pulsed-wave Doppler US.

Conclusion 

Doppler US has been found to distinguish between stenosis with a diameter reduction greater than or less than 50% (corresponding to an area reduction of 70%) with a sensitivity of 77%-82% and a specificity of 92%-98% [18,20-24]. Complete scanning of both lower extremities may require up to 2 hours depending on the operator’s experience [18]. However, if the operator is familiar with the US anatomy of the lower extremity arteries and understands the parameters and Doppler waveforms of Doppler US, accurate diagnostic results can be produced with less scanning time.