New Clinical Indications for Embolization Procedures
Hildegard Kaulen, PhD | Thu Jul 06 00:00:00 CEST 2017
Transarterial embolization procedures are a recognized therapy option for hepatocellular carcinoma (HCC), which is a type of liver cancer. University Hospital Frankfurt is increasingly combining these procedures with new angiographic technology to also treat benign prostatic hyperplasia and uterine fibroids.
You can tell that Thomas Vogl, MD, is a successful interventional radiologist just by looking at his desk, on which dozens of little glass trophies are lined up, given to him partly by grateful patients. For the last 18 years, Vogl has been director of the Institute for Diagnostic and Interventional Radiology at University Hospital Frankfurt, where he has set up one of the biggest transarterial chemoembolization (TACE) centers in Germany. With its reputation, the center attracts worldwide attention among cancer patients, who come to Frankfurt to receive interventional treatment. Vogl has performed TACE for hepatocellular carcinoma over 5,000 times, and every year he and his internist and surgeon colleagues see around 250 new patients. Vogl treats half of these new patients with chemoembolization. In this procedure, chemotherapeutic drugs and embolic agents are injected directly into the tumor via the hepatic artery. Besides this, Vogl also performs a whole range of vascular procedures, which regularly accrue in a large German university hospital and for which he needs good image quality, low dose, and short intervention times. For a while now, he has also been exploring new indications for embolization procedures using ARTIS pheno, a novel, robotic angiographic technology.
Vogl likes the new system because the image quality he demands for his procedures can now be obtained at considerably lower doses. Furthermore the system gives him the opportunity to choose: In critical situations he is able to invest in superior image quality, still without exceeding the dose levels he was used to in the past. “We’re now increasingly addressing indications that we couldn’t do previously, because we weren’t able to resolve certain anatomic structures or inflict such high doses on the patient,” explains Vogl. He uses the improved image quality in the embolization of the prostate in cases of benign prostatic hyperplasia. The lower dose helps when it comes to embolizing uterine fibroids. “The half-dose is a powerful argument for young women who still want to have children.”
Shorter intervention time for greater safety
For Vogl, short intervention times are also important, because they affect the safety of the procedure. “Thanks to the good image quality, we can now reach the tumor more quickly because we can navigate our way faster through complex organs like the prostate when doing interventions. This means there’s less risk of complications, mainly due to reduced procedure time,” explains Vogl. “I would gain nothing if I were to use equipment with a low dose and low resolution but took twenty minutes instead of ten,” he continues. Using ARTIS pheno, Vogl can embolize both the liver and the prostate faster than before.
To protect himself and his team from unnecessary radiation, Vogl recently requested the X-ray dose required for all organ programs in the new system to be further reduced. Now Vogl only resorts to the previous programs with the original dose if the image quality is not sufficient. Hence, for each intervention he decides what matters more: better image quality or lower dose. “I always start out without the extra dose,” he says. “I’ll only use the button to switch to a higher dose if I notice that it’s taking longer to probe the vessels or if I encounter difficulties.” A member of Vogl’s team is currently evaluating all the examination reports to identify the clinical situations in which he switches to the higher dose. Vogl and his team hope this will produce interesting insights into precisely what is required in procedures of this sort.
Vogl also sees it as a great advantage that he can display earlier CT and MRI images on one of the two monitors and view them with the real-time image. This enables him to use information from preoperative examinations, such as the excellent soft tissue contrast displayed in MRI images. “This extra visual information helps me set the C-arm to always give me the best possible view of the vessels. Then I can see very precisely where and using which angulation I can get the best view of the vascular junctions,” says Vogl.
Perfusion and prognosis
Vogl begins the TACE for hepatocellular carcinoma with a syngo DynaCT run. He does two 3-second scans with a rotation of 200o each. A native scan, known as a mask run, is followed by a contrast run involving the injection of contrast agent. Vogl then uses the syngo DynaPBV Body application to evaluate the volume of blood in the parenchyma of the tumors. These DynaCT data provide information about the localization and blood volume of the liver tumors, and can give a prognosis on response to treatment. “On the basis of our experience and a large number of examinations we know that well-perfused tumors respond better to chemotherapeutic drugs than those with a poor supply of blood,” explains Vogl. “The rule of thumb in oncology says that if it grows quickly, it can also go away quickly. For this reason it is easier to treat a fast-growing tumor than a slow-growing one.” He adds that no matter how much cytostatic agent you pour on resting cells, nothing will happen.
On the basis of the derived perfusion, Vogl also decides what kind of cytostatics he is going to use and in what dose. “Prognosis is difficult for blood volume values of less than 80 ml. In these cases you have to chemoembolize very aggressively,” says Vogl. “You can expect good results with blood volume values between 80 and 120 ml. For values of more than 120 ml, chemoembolization is going to work extremely well.”
So how successful is TACE in cases of hepatocellular carcinoma? “That depends on how well we select patients. If perfusion imaging shows poor blood flow, we’ll opt for a different therapy rather than repeating the chemoembolization,” continues Vogl. For every fifth patient with HCC who he treats using TACE, the intervention is the bridge to a curative therapy. “If, for example, we have a patient with six to eight lesions in their liver, the surgeon can remove a hepatic lobe, and we’ll do the rest with chemoembolization.”
Application to probe tumor feeders
The new system was also equipped with a new application called syngo Embolization Guidance for probing the tumor feeding vessels. The application uses color coding to show the anatomy of the arteries. Vogl mainly uses the software for probing the prostate. “syngo Embolization Guidance is so exciting with this organ because I need scans at extreme angles and have to see very clearly where the arteries are going,” he explains. When embolizing the liver, Vogl relies on the experience he has gathered in the course of more than 5,000 procedures. “My staff also uses syngo Embolization Guidance for the liver,” he explains. “The application is a great help for anyone with lesser experience.”
The system’s low acquisition dose allows Vogl to end the TACE procedure with another DynaCT run: “From this scan, I can see immediately how the embolic agent has dispersed, whether it has reached the right place, whether there’s bleeding, and whether anything has been displaced.” Vogl also likes the new hygiene approach of the imaging system. The growing number of hospital infections and multi-resistant pathogens pose a major threat, particularly for patients with serious primary diseases. “The new system helps us keep the risk of infection in the angio suite as low as possible,” says Vogl. He knows that he is dealing with a vulnerable group of people.
About the Author
Hildegard Kaulen, PhD, is a molecular biologist. After sojourns at Rockefeller University (New York) and Harvard Medical School, since the mid-1990s she has worked as a freelance scientific journalist writing for prestigious daily newspapers and science magazines.
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