Tips for Performing Bland Embolization
Bland embolization, an interventional technique derived from the concept of dual blood supply to the liver, was the subject of a presentation at CIO 2018 by Karen Brown, MD, FSIR. Dr. Brown is an interventional radiologist at Memorial Sloane Kettering Cancer Center in New York. In her presentation, Dr. Brown reviewed the characteristics of the embolizing agents, the pre- and post-procedure protocols she follows, and other key tips for performing the procedure.
The particles used for bland embolization need to penetrate into the tumor and thus should be small, relatively inert/biocompatible, and preferably hydrophilic. “It helps if they’re calibrated so that you have some sense of what size particle you’re delivering,” said Dr. Brown. “The three that I’ve worked with thus far are Embosphere microspheres, Embozene, and BeadBlock. There’s now HydroPearl too, but I have no experience with that at the moment since it’s a recent arrival on the scene.”
Before treatment, Dr. Brown decides what type of particle is optimal for the specific case and then reviews the scan. Colleagues have often talked about ensuring that the portal vein is patent, but her preference is to address that on the CT. She does an SMA run in order to know the direction of flow. “Child-Pugh classification is a blunt instrument for assessing liver disease, and if I see a patient who on the SMA or splenic run has hepatofugal flow, that informs my embolization. It may make me decide to treat the patient in two sessions rather than one, or it just may inform my stopping point,” said Dr. Brown.
Regarding particle size, Dr. Brown uses the smallest particles, less than 100 μm, for small tumors that she is treating selectively. If the tumors are very big and around the diaphragm, she will use bigger particles (100 to 300 μm). However, if a tumor is hypervascular, extends into the hepatic veins, or is fed by a systemic artery such as the phrenic, then “you have to worry about small particles passing into pulmonary circulation. If that happens, it’s almost uniformly fatal,” she said. Thus, she would not use 40 to 120 embospheres or any smaller particles for those patients.
Pre- and Post-Procedure Protocols
Patients receive dronabinol and antibiotic in the PFC prior to the procedure, and they receive 8 mg of dexamethasone and 30 mg of ketorolac intraoperatively. After the procedure, patients stay overnight in the hospital and are given only clear liquids.
Ketorolac is given around the clock instead of on-demand because patients tend to feel better if the treating physician stays ahead of potential pain, nausea, and vomiting. “With this new regimen, about 60% of my patients go home the next afternoon,” Dr. Brown commented. One month after the procedure, patients are followed up with a scan to evaluate the results and then are followed quarterly thereafter with scans.
Dr. Brown used a case example to illustrate some of the techniques important to the procedure. A woman who had lymphoma and a history of HCV had a follow-up scan of her lymphoma that incidentally revealed a new solitary liver lesion that was a little less than 2 cm. With the patient in question, the embolization took 0.5 cc of 40 μm Embozene. “You have to be very patient,” Dr. Brown said. “You have to suspend the 40 μm Embozene well. I actually doubled the amount of contrast that I typically add so that I have about 20 ccs in the syringe, and you have to give it slowly because you don’t want it all to come out like toothpaste and plug up the bigger vessels. You want it well suspended so it flows out into the intratumoral vessels.”
To conclude the presentation, Dr. Brown offered a few further tips. She finds that using anesthesia is helpful, even though she has been against its use in the past. “When we first had anesthesia, I was against it; it seemed to me it was too complicated. But now I believe now that what I can’t see, I can’t treat. I use the combination of cone beam CT, regular CT, and anesthesia. A lot of times I can see what I need to see with anesthesia.” She also finds that anesthesia allows patients to feel more comfortable when cases are particularly long in duration.
She emphasized again the importance of using small, tightly calibrated particles for selective embolization, particularly for solitary lesions. No chemotherapy is necessary in those cases. Additionally, operators must embolize to stasis, which means that the contrast does not go anywhere. Immediately post-embolization, a CT should be performed because it not only shows the uptake, but also correlates with response. Corticosteroids and ketorolac are given intraoperatively and not on demand, and ketorolac is continued around the clock if possible. To evaluate the results of the procedure, the patient is given a follow-up scan after 1 month. Additional scans are conducted quarterly.
Brown K. Craftsmen’s Corner: Techniques in Liver-Directed Therapy. Bland Embolization. Symposium on Clinical Interventional Oncology. Feb 3 2016. Hollywood, Florida.