Ultrasound News: Launching Pad
By Ronald Hidalgo, MD
Vol. 20 No. 10 P. 8
Improved ultrasound technology benefits hemodynamic imaging.
When a patient enters a health care facility, they do so hoping that they will leave with an explanation for their symptoms and a way to get better. In this regard, it’s a very exciting time to be in the field of radiology, as rapid advancements are providing clearer and safer ways to diagnose a patient.
Ultrasound, which is often a first-line diagnostic modality, has come a particularly long way since it was first used for medical reasons in the 1920s and 1930s. In addition to advancements that allow the device to be smaller and, therefore, more portable, there have been significant improvements in the quality of the image it delivers.
Improved image quality increases the chance that sonographers can capture not only a picture but also physiologic information that is more likely to lead to the radiologist making an accurate diagnosis. One way this is accomplished is by improving the ability to capture hemodynamics. Better images and physiologic information also expand the number of instances where ultrasound can be used, instead of higher modalities such as CT, which is more expensive, can require premedication, produces more anxiety, and exposes patients to radiation. Today, my practice uses the Samsung RS85 ultrasound system.
An example of improved ultrasound imaging as it relates to hemodynamics was demonstrated in a case of a 34-year-old woman who presented in the emergency department (ED) complaining of two to three days of a burning sensation while urinating, intermittent hematuria, and right-side flank and back pain. She had a history of prior pyelonephritis, but imaging was needed to make a diagnosis.
The ED doctor ordered a noncontrast CT scan of her abdomen, which came back with nonspecific results. The doctor then ordered a renal ultrasound and, during the exam, we were able to find a very subtle area using grayscale Doppler that showed a hyperechoic region along the cortex on the inferior right kidney. We added both color Doppler and a technology called MV-Flow, which helps view microvascular vessels, and were able to identify that the small vessels were indeed compressed by edema, resulting in ischemia and altered blood flow.
We were able to diagnose the patient with pyelonephritis and treat her accordingly. In the end, the improved image quality and advanced capabilities of the ultrasound technology allowed us to avoid exposing the patient to additional radiation with a contrast CT scan; in younger patients, we try to minimize dose exposure as much as we can. While this finding is considered a hallmark finding in ultrasound, it is often difficult to obtain; with the improved technology, it became clearer.
Expanding Clinical Uses
There are times when ultrasound is the clear first-line modality for evaluations. Patients who present in the ED with nonspecific leg pain are often sent directly to ultrasound. The concern is typically deep vein thrombosis, which is fairly common and affects about 1 in 1,000 people each year; it can lead to a pulmonary embolism. Ultrasound is used to identify a clot that may be affecting patency in the thigh and calf veins; however, getting clear images of calf veins can be challenging because the calf has small vessels and, at times, its blood flow is very slow. Complicating matters is the fact that many ED patients present with comorbidities such as obesity, which present additional imaging challenges.
As a sonographer performs the ultrasound, it is common when using color Doppler to compress the leg more distally to visualize flow. When augmentation is needed, it becomes harder to discern what is being seen because the process can cause blooming that impacts clarity. Advances in vascular analysis are now allowing ultrasound to visualize hemodynamics in smaller and slower vessels. Along with improved resolution, this has reduced the number of instances where the calf veins are suboptimally evaluated.
Other areas where improved image quality can help assess or study hemodynamics include the following:
• Prebiopsy for thyroid nodules. Small vessels can help identify the vascularity of the nodules and the possibility of targeting components of a nodule for biopsy. Research can also be performed to determine whether microvascularity can further risk-stratify nodules where normal color Doppler has been unreliable.
• Identifying portal vein thrombosis. A consequence of liver disease is that the portal vein can become clotted. Typically, ultrasound is the first modality used for vascular assessment, but there are times when it’s not possible to obtain a clear enough picture, so the patient is sent for a CT scan. With improved technology and contrast, it may be possible to prevent patients from needing a CT or MRI because we will be able to identify whether the vein is patent or not.
• Identifying ovarian torsion. Ultrasound is also the front-line modality to assess for ovarian torsion because it can show whether there is a lack of patency to the ovary. Advanced imaging of vasculature will help increase the confidence of this important diagnosis.
• Imaging the carotid. The use of volume probe-assisted ultrasound imaging is allowing sonographers to transform 2D sound waves into 3D images. This is helping to capture images of the carotid artery in a new way. Through volume imaging and AI, we can produce 3D maps for risk analysis and uniform analysis of stenosis.
As medical technology continues to rocket into the future, the uses of ultrasound will only continue to expand. In a medical field that continually searches for less expensive, less invasive, and safer ways to diagnose and treat patients, ultrasound will no doubt continue to increase as the first-line modality to diagnose a growing list of conditions.
— Ronald Hidalgo, MD, is a member of Clinical Radiologists in Springfield, Illinois.