Tag Archives: Vascular ultrasound

The Expanding Scope and Diagnostic Capabilities of Vascular Ultrasound

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Peripheral Vascular Disease (PVD) in the United States affects approximately 8 million to 12 million patients a year; some experts in the field believe this number may be underestimated. The disease is associated with significant cardiovascular morbidity and mortality, with a high rate of fatal and non-fatal cardiovascular events, such as myocardial infarction, stroke, renal failure, limb amputations, abdominal aortic aneurysms, pulmonary embolus, and progressive ischemic end-organ dysfunction. The reduction in quality of life from global vasculopathy in many patients can thus be significant.

George Berdejo

George Berdejo, BA, RVT, FSVU

Prompt and accurate diagnosis of these disease processes is of utmost importance and high-quality vascular ultrasound plays an essential role. In fact, vascular ultrasound and the role of the vascular ultrasound professional has evolved and expanded rapidly and is at the core of modern vascular disease care in the United States and is emerging around the world.

Vascular ultrasound can be seen at the intersection of imaging, physiology, physiopathology, interventional medicine, and surgery and is utilized widely by healthcare providers from many specialties, including but not limited to vascular technologists and other subspecialty sonographers, vascular surgeons, vascular interventional radiologists, vascular medicine physicians, cardiologists, radiologists, and other vascular specialists with an interest in vascular disease.

At the core of any thriving vascular surgery practice is high-quality vascular ultrasound imaging. Duplex vascular ultrasound (DU) is used to evaluate all of the major vascular beds outside of the heart. The use of duplex ultrasonography for the study of vascular disease is firmly established but is also rapidly expanding. Thanks to continued improvements in the performance of ultrasound devices, vascular ultrasound can be used to perform a greater range of assessments in a noninvasive manner in some cases excluding the need for more invasive, expensive, contrast-based imaging modalities.

The recent proliferation of “less and minimally invasive” endovascular options currently available and offered to patients with various vascular disease processes has mandated better, less invasive, preferably noninvasive methods, to diagnose the disease that is being treated. Advances in technology have increased the diagnostic capabilities of vascular ultrasound and its role not only in diagnosis but also in planning and performing interventions and in patient follow-up and surveillance after intervention. Indeed, vascular ultrasound has become the standard “go-to” diagnostic imaging technique prior to most vascular interventions and has certainly emerged as the imaging technique of choice for following patients after most vascular interventions.

Endograft Evaluation. Duplex vascular ultrasound has emerged as the standard of care for surveillance after endovascular repair of abdominal aortic aneurysms. A major complication of this procedure is endoleak (persistent or recurrent flow within and pressurization of the residual aneurysm sac). This results in persistent risk of aneurysm rupture and potential death. Ultrasound assessment allows imaging and Doppler interrogation of deep structures and low-flow detection capabilities needed in patients with low-volume/low-velocity endoleak. Duplex vascular ultrasound, in good hands, has supplanted computed tomographic angiography as the primary surveillance technique in these patients. In addition, DU allows for the ability to resolve the deep structures of the abdomen to measure aneurysm sac size.

Hemodialysis Access Mapping and Surveillance. Higher frequency, better resolution, smaller footprint transducers that are currently available provide the high-resolution images that are needed to assess the veins and arteries of the upper extremity in order to plan the optimal access sites and also to provide the surveillance often needed postoperatively in order to maximize the life of the access and the quality of life for the dialysis patient.

Lower Extremity Vein Reflux Testing. Chronic venous insufficiency (CVI) is a condition that occurs when the venous wall and/or valves in the leg veins are not working effectively, making it difficult for blood to return to the heart from the legs. An estimated 40 percent of people in the United States have CVI. The seriousness of CVI, along with the complexities of treatment, increase as the disease progresses. Duplex ultrasound is integral in the evaluation, treatment and follow-up of these patients. Absent the appropriate equipment, the initial duplex reflux scan is among the most physically challenging, labor-intensive scans performed in vascular ultrasound. These exams account for 20%–25% of all the ultrasound scans performed in our practice.

Lower Extremity Arterial Mapping. Our philosophy regarding the practical evaluation of patients with known peripheral arterial disease who require intervention includes the use of duplex ultrasound as the primary first-line imaging modality precluding the use of more expensive, invasive, and nephrotoxic diagnostic arteriography in most patients.

Vascular ultrasound is now being used by increasing numbers of specialists who are employing both traditional and newer cutting-edge methods and techniques to improve patient care and management and who are dedicated to the delivery of quality care to their patients.

The future is bright for both vascular ultrasound and the vascular sonography professional!

 

Do you have any tips for performing vascular ultrasound? Comment below, or, AIUM members, continue the conversation on Connect, the AIUM’s online community to share your experience.

 

 

George Berdejo, BA, RVT, FSVU, is Director of Vascular Ultrasound Outpatient Services at White Plains Hospital in White Plains, New York. He is the Chair of the AVIDsymposium (www.AVIDsymposium.org) and is the current Chair of the Cardiovascular Community of the AIUM.

Ultrasound in Orthopedic Practice

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Point-of-care ultrasound brings great value to patient care in orthopedic practice, especially for soft tissue problems. It offers safe, cost-effective, and real-time evaluation for soft tissue pathologies and helps narrow down the differential diagnosis.Pic1

There are a variety of soft tissue lesions in orthopedic practice with a classic clinical presentation that may not necessitate ultrasound examination for confirmation of diagnosis, for example, ganglion cyst. However, there is value in performing an ultrasound scan for these common soft tissue lesions.

Ganglion cyst on the dorsum of the wrist or radial-volar aspect of the wrist are confirmed based on clinical examination and presentation. Adding ultrasound examination can help differentiate classic ganglion cyst from some rare findings like Lipoma, anomalous muscles, or soft tissue tumors. Ultrasound examination may also be helpful in finding the source of the ganglion cyst or the stalk of the ganglion cyst. This can help pre-surgical planning if resection of the ganglion cyst is desired by the patient and recommended by the surgeon, because arthroscopic or traditional surgical approach may be needed based on the location of the stalk or neck of the cyst.

Images 1 and 2 show examples of two different patients with a similar presentation of slow-growing mass on the digit. Image 1 from patient 1 shows a solid tumor overlying the flexor tendons of the digit, where the mass was palpated. Image 2 from patient 2, shows a cystic mass overlying the tendons of the digit. In both of the cases, masses were painless and slow growing with minimal to no discomfort. Ultrasound is a great tool in differentiating solid vs cystic lesions and can help avoid attempted aspiration of a solid mass when the mass is presented in an area of classic ganglion cyst’s usual presentation.

Another soft tissue problem, where ultrasound is a superior imaging tool is tendon pathology. Ultrasound can help differentiate tendinosis, tenosynovitis, or tendon tears.

In tenosynovitis, tendon by itself shows normal echotexture and uniform appearance but the tenosynovium that surrounds the tendon gets inflamed and appears as hypoechoic halo around the tendon, for example, in image 3, tendons of the first dorsal compartment of the wrist show uniform thickness and fibrillar echotexture, however there is hypoechoic swelling around the tendons, this is an example of tenosynovitis of first dorsal compartment of the wrist.

In tendinosis, tendon loses its fibrillar pattern and appears swollen and may show vascularity on color ultrasound, which is suggestive of neoangiogenesis or angiofibroblastic proliferation. For example, in Image 4, the tendons of the first dorsal compartment of the wrist show focal enlargement, hypoechoic swelling, and loss of normal fibrillar echotexture and tendon appears disorganized with evidence of increased vascularity on color ultrasound. This is an example of tendinopathy or tendinosis.

Focal tendon tears appear as anechoic or hypoechoic focal defects in tendon substance. Image 5 shows a partial tear of the triceps tendon from the olecranon process. The partial tear appears as a focal hypoechoic defect in the tendon, which is confirmed in the long and short axis scan of the tendon.

In full-thickness tears, the tendon is seen retracted proximally with no fiber attachment at the tendon footprint. Image 6 shows an example of a full thickness complete tear of the supraspinatus tendon from its bony attachment at the greater tubercle. The tendon has retracted proximally and the retracted stump is not visible on ultrasound examination.

Image 6

Point-of-care ultrasound adds significant value to clinical examination in an orthopedic setting. It enhances the understanding of a patient’s problem, increases confidence in the care provided, and high patient satisfaction is reported.

In what unexpected ways do you find ultrasound to be useful? Do you have additional tips for using ultrasound in orthopedics?  Comment below or let us know on Twitter: @AIUM_Ultrasound.

Mohini Rawat, DPT, MS, ECS, OCS, RMSK, is program director of Fellowship in Musculoskeletal Ultrasonography at Hands On Diagnostics and owner of Acumen Diagnostics. She is ABPTS Board-Certified in Clinical Electrophysiology; ABPTS Board-Certified in Orthopedics; registered in Musculoskeletal Sonography, APCA; and has an added Point-of-Care MSK Soft Tissue Clinical Certificate.

Determining Umbilical Cord Blood Flow

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Umbilical cord blood flow is among the most highly desired parameters for monitoring fetal well-being. This is because cord blood flow directly reflects placental volume flow, which is considered to be as important in the fetus as cardiac output and lung perfusion are in adults.1 Yet, presently employed noninvasive methods, such as umbilical artery Doppler waveform analyses, use surrogate flow evaluation parameters, such as systolic/diastolic ratios, which do not directly reflect placental-fetal blood flow.2,3 Volume flow estimation overcomes this by measuring true flow, and it has been shown that volume flow changes in the umbilical vein occur before umbilical artery flow indices become abnormal.4

Yet, the present volume flow measurement method has severe problems limiting its utility. These include technical difficulties in flow measurement in umbilical cords and faulty assumptions employed in the measurement. The present method using spectral Doppler is

                 Q = V × A                    (1),

where Q is volume flow, V is the mean velocity through the Doppler sample volume, and A is the cross-sectional area of the vessel of interest. This formula assumes that the 2D flow profile is cylindrically symmetric with a circular cross-section, and the line of the Doppler sampling cuts perfectly through the center of the sampled vessel. The velocity estimates require angle correction, and if the vessel is tortuous, as in umbilical cords, the sampling position placement and angle correction are hard to perform. Multiple investigators have warned that small errors in volume flow components can result in large errors in the calculation of volume flow.5-7

A new, easy-to-perform volume flow method overcomes almost all of the limitations of the standard technique. The new method is angle independent, flow profile independent, and vessel geometry independent. It works as follows:

Volume flow is defined as the total flux across any surface, S, intersecting the vessel. This is written as

Eq2

where Q is again volume flow, V is the local velocity through each area element dA, and “∙” is the dot product which projects the local velocity V onto the normal vector for each area element. This is known as Gauss’s theorem. The intersecting surface, known as the “C” surface, is very simple to obtain using 3D ultrasound (Figure8). In order to validate this method, we obtained an AIUM EER-funded research grant.

Fig

Figure: (A) Four-panel view of a single 3D color flow acquisition of the umbilical cord. The four views are as follows: upper-left is axial-lateral, upper-right is axial-elevational, bottom-left is elevational-lateral (ie, the c-surface), and bottom-right is a rendered 3D reconstruction. Arteries are shown in blue and the vein is shown in red. The schematic in (B) illustrates the orientation of the probe and the corresponding c-surface in the elevational-lateral imaging plane. The vessel colors in (B) match the directionality in (A). The entire umbilical cord passes through the c-surface but only the cross-sections of the umbilical arteries and umbilical vein are illustrated in (B). The two arteries are separated in power Doppler (not shown). (Printed with permission from Pinter et al. J Ultrasound Med. 2012;31(12):1927-34. © 2016 by the American Institute of Ultrasound in Medicine)

We had 2 specific aims: 1) Test the reproducibility of the volume flow measurement, and 2) evaluate the relationship of volume flow to clinical outcome in a high-risk patient population.

In the first aim, we performed studies on 35 subjects between the gestational ages of 22–37 weeks, 26 high risk and 9 normal.9 We attempted to measure umbilical cord blood flow at 3 sites in the cord in each subject, and we averaged 28.3 ± 3.3 (mean ± standard deviation) samples per site. We used a GE LOGIQ E9 ultrasound system with a 2.0–8.0 MHz bandwidth convex array transducer to acquire multiple volume 3D color and power mode data sets. Since we were measuring mean blood flow, we assessed variability using relative standard error (standard error /mean) (RSE). The average RSE for blood flow at each cord position was ±5.6% while the average RSE among the measurements in each subject was ±12.1%.

For the second aim, we compared the volume flow measurements in 5 subjects that developed preeclampsia with the 9 normal subjects. Even with these small numbers, we detected a significant difference between the mean depth-corrected, weight-normalized umbilical vein blood volume flows in the two groups (P = .035). Further, blood flow abnormalities were detected either at the same time or preceded the hypertensive disorder in 4 of the 5 subjects. This is consistent with our prior publication where blood flow changes preceded the onset of pre-eclamptic symptoms in a study subject.8

With the introduction of 2D array transducers, umbilical cord volume flow estimates can be performed in seconds and given the valuable information provided by this method, umbilical cord volume flow will hopefully become a standard component of fetal examinations.

References:

  1. Tchirikov M, Rybadowski C, Huneke B, Schoder V, Schroder HJ. Umbilical vein blood volume flow rate and umbilical artery pulsatility as ‘venous-arterial index’ in the prediction of neonatal compromise. Ultrasound Obstet Gynecol. 2002;20:580-5.
  2. Newnham JP, Patterson LL, James IR, Diepeveen DA, Reid SE. An evaluation of the efficacy of Doppler flow velocity waveform analysis as a screening test in pregnancy. Am J Obstet Gynecol. 1990;162:403-10.
  3. Acharya G, Wilsgaard T, Bernsten GKR, Maltau JM, Kiserud T. Doppler-derived umbilical artery absolute velocities and their relationship to fetoplacental volume blood flow: a longitudinal study. Ultrasound Obstet Gynecol. 2005;25:444-53.
  4. Rigano S, Bozzo M, Ferrazzi E, Bellotti M, Battaglia FC, Galan HL. Early and persistent reduction in umbilical vein blood flow in the growth-restricted fetus: a longitudinal study. Am J Obstet Gynecol. 2001;185:834-8.
  5. Evans DH. On the measurement of the mean velocity of blood flow over the cardiac cycle using Doppler ultrasound. Ultrasound Med Biol. 1985;11(5):735-41.
  6. Gill R. Measurement of blood flow by ultrasound: accuracy and sources of error. Ultrasound Med Biol. 1985;11:625-41.
  7. Lees C, Albaiges G, Deane C, Parra M, Nicolaides KH. Assessment of umbilical arterial and venous flow using color Doppler. Ultrasound Obstet Gynecol. 1999;14:250-5.
  8. Pinter SZ, Rubin JM, Kripfgans OD, Treadwell MC, Romero VC, Richards MS, Zhang M, Hall AL, Fowlkes JB. Three-dimensional sonographic measurement of blood volume flow in the umbilical cord. J Ultrasound Med. 2012;31(12):1927-34.
  9. Pinter SZ, Kripfgans OD, Treadwell MC, Kneitel AW, Fowlkes JB, Rubin JM. Evaluation of umbilical vein blood volume flow in preeclampsia by angle-independent 3D sonography [published online ahead of print December 15, 2017]. J Ultrasound Med. doi:10.1002/jum.14507.

How do you determine umbilical cord blood flow? What problems have you encountered using the traditional method? Comment below or let us know on Twitter: @AIUM_Ultrasound.

Jonathan Rubin, MD, PhD, FAIUM, is Professor Emeritus of Radiology at University of Michigan.

Vascular Access for Fiona

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Life as a vascular access nurse can be very challenging and diverse in a pediatric hospital. A typical day is fast-paced and includes neonatal, pediatric, and adult patients. Veins may be small, tortuous and often found in unusual locations, eg an extremity or scalp vein. For many patients, imaging tools such as ultrasound are essential for successful placement of IVs, midline catheters, and PICCs. The Vascular Access Team sees patients in both the inpatient and outpatient settings. While many of our procedures are routine, a phone call in February 2017 forever changed the way we view our specialty of vascular access.

The caller on the phone was Amy from the Cincinnati Zoo Marketing Department. She described an urgent clinical situation with Fiona, a 3-week-old premature hippo who was dehydrated and needed IV access. The Zoo staff was desperate as Fiona was not taking any bottles and her IVs were only lasting 8–12 hours. Amy had previous experience with the Vascular Access Team when her daughter had surgery at our institution. She referred to our team as the “Vein Whisperer.” Amy wanted to know if we would be able to use the same tools we used on her daughter to gain IV access with Fiona.pic 8

Fiona was already a star in the eyes of the Cincinnati community. Fiona was born on January 24, 2017, the first premature hippo on record to survive. Fiona was small, around 30 pounds, and was being cared for by a specialized team of experts at the Zoo. Her day-to-day progress was being reported on social media and the local news.

My answer to Amy was, “Of course we can help Fiona!” In my mind, I was thinking of all the things we would need to bring to the Zoo. Supplies included an ultrasound machine, probe cover, ultrasound gel, skin antisepsis, varying sizes and lengths of IV and midline catheters, dressings, etc. I kept thinking…this is a premature hippo, what will we need to insert and maintain the catheter? I asked my colleague Blake to accompany me to the Zoo. Blake is an experienced vascular access nurse and is always up for a challenge! We gathered all our supplies and began our journey to the Zoo.

We arrived in the Hippo Cove area of the Cincinnati Zoo. We met two of the veterinarians who updated us on her condition. Fiona was dehydrated, on oxygen, and extremely weak. They described her condition as critical. We put on special scrubs and removed our shoes. As we were led into the small room where Fiona was, the room temperature was very warm as an effort to maintain Fiona’s body temperature. Fiona was on the floor, laying on a blanket.

Fiona was surrounded by 2–3 Hippo team specialists. Amid their worried looks, they quickly reviewed Fiona’s history, IV access issues, and her inability to take a bottle. Fiona was receiving nutrition through an intermittent naso-gastric tube.

Time was of the essence; we began setting up the 2D ultrasound machine and the necessary supplies. Initially, I scanned her head to assess for any scalp veins, there were no visible veins identified. Blake began scanning her hind leg; she was able to locate a viable vein, about 0.2 cm below the skin. The vein easily compressed and had a straight pathway. Based on her assessment and fluid requirements, we decided to use a 3Fr 8cm midline catheter.

The vein was accessed under ultrasound guidance, using a transverse approach. The midline catheter initially threaded with ease but we were unable to advance it fully. Fluids were connected to the catheter but it only lasted 20 minutes before leaking. The midline catheter was discontinued. Another vein was visualized under ultrasound guidance on the hind leg; the midline catheter was trimmed to 7 cm and threaded with ease. The midline catheter flushed and aspirated with ease.

pic1

Due to Fiona’s occasional activity of standing up, we really wanted a secure catheter. The midline catheter was sutured to her skin and a dressing was applied. We discussed the care and maintenance with the veterinary staff, and the decision was made to infuse continuous fluids through her midline catheter to maintain patency.

Over the next 2 days, Fiona gradually began to regain her strength. She began slowly taking her bottles and standing up. Fiona received 5 liters of fluids over 6 days through her midline catheter. The catheter was discontinued on day 6.

Fast forward and now Fiona has celebrated her 1st birthday. She did so with the Hippo team that provided the delicate care that she needed. The Vascular Access Team is so proud to have been part of her care. On that cold February day, we were able to use our 20+ years of experience and knowledge to provide the right catheter under imaging to provide her with the lifesaving fluids she needed.

Have you performed ultrasound in an unusual situation? Tell us your story by commenting below or letting us know on Twitter: @AIUM_Ultrasound.

Darcy Doellman MSN, RN, CRNI, VA-BC, is Clinical Manager of the Vascular Access Team at Cincinnati Children’s Hospital.