Radioembolization offers a novel way to treat the nonresectable, liver predominant hepatic malignancies with better tumor response and overall progression-free survival rates. Transarterial catheter-based radioembolization procedure involves the hepatic arterial administration of glass- or resin-based beta emitting Yttirum-90 microspheres. Safe delivery of the tumoricidal radiation dose requires careful angiogram planning and coil embolization to quantify lung shunting and prevent systemic toxicity, respectively. Diagnostic pretreatment angiogram also serves to identify the hepatic arterial variant anatomy and other coexisting pathologies that might require a different or alternative approach. We describe a complex case of celiac artery stenosis with tortuous pancreaticoduodenal arterial arcade precluding access to the right hepatic artery for performing radioembolization. Celiac artery stenting of the stenosis was performed to facilitate subsequent safe and successful Yttrium-90 microsphere radioembolization.
A 74-year-old female with metastatic colorectal carcinoma to the right hepatic lobe (T4 N2 M1 at presentation) is status post colon and segment VI hepatic resection, and chemotherapy. She was referred for Yttrium-90 (90Y) radioembolization procedure for treatment of unresectable stable right hepatic lobe metastatic lesions (Figure
Contrast enhanced CT scan images demonstrate low attenuation right hepatic lobe lesions consistent with known metastatic disease (white arrows, (a) and (b)). Patient is status post partial segmental resection of the right hepatic lobe (black arrow, (c)).
A planning or mapping angiogram was performed. The aortogram demonstrated a tight (approximately >90%) stenosis of the proximal celiac axis with mild poststenotic dilatation (Figure
(a) Aortogram demonstrates a tight stenosis of the proximal celiac axis (white arrow) with mild poststenotic dilatation. In this case, the celiac artery stenosis was assumed to be related to atherosclerosis. The stenosis limits the access of the hepatic arterial branches for radioembolization purposes. Prior surgical clips related to partial right hepatic resection are noted (black arrow). (b) Superior mesenteric artery angiogram demonstrates significant hypertrophy and enlargement of the inferior pancreaticoduodenal arcade with opacification of gastroduodenal artery, and hepatic branches in a retrograde fashion (white arrows). There was a small collateral vessel which traveled from the superior mesenteric artery in a superior direction and opacified the very distal celiac axis and splenic artery (black arrow) likely representing the Arc of Buhler. (c) The right hepatic artery was not accessible through the tortuous pancreaticoduodenal collateral arcade (white arrow).
Treatment phase right hepatic angiogram images (a, b) demonstrate celiac artery stenting (6 × 15 mm Cordis chromium balloon expandable stent, white arrows) resulting in widely patent celiac axis with accessibility to the hepatic arteries. Coil embolization of gastroduodenal artery (two 10 mm × 10 cm tornado coils and two 8 mm × 4 cm coils, black arrows) prevents abnormal extrahepatic distribution. Additionally, a small accessory right hepatic branch was also coil embolized (two 3 × 2 mm platinum coils, white line arrows on (b)) to allow safer dose delivery and probable intrahepatic vascular flow redistribution [
During the mapping angiogram phase, 5 mCi of technetium-99m labeled macroaggregated albumin was injected within the right hepatic artery to quantify the liver-lung shunt. The planar scintigraphic images demonstrate distribution of the radiotracer within the right lobe of the liver without any abnormal extrahepatic distribution. Regions of interest were drawn within the lungs and liver resulting in an estimated maximum lung shunting of 3%.
Approximately 27.8 mCi (1029 MBq) of 90Y microspheres (110% of calculated dose) was administered within the right hepatic artery through the stented celiac artery approach during the treatment phase utilizing the standard protocol till the end point. Bremsstrahlung images obtained after the 90Y radioembolization confirm proper delivery of microspheres to the targeted region without any abnormal extratumoral distribution (Figure
Posttherapy Bremsstrahlung image of the abdomen confirms proper delivery of microspheres to the targeted region of the right hepatic lobe (white arrow) without any abnormal extratumoral distribution. Safe and effective microsphere radioembolization with minimal to no radiotoxicity requires careful planning and preparation.
Microsphere radioembolization therapy is currently approved for unresectable hepatic metastatic disease from colorectal cancer (SIR-Spheres, Sirtex Medical, Lane Cove, NSW, Australia) and unresectable hepatocellular carcinoma as a humanitarian device exemption (TheraSphere, MDS Nordion, Ottawa, ON, Canada) within the United States. 90Y microspheres are permanent biocompatible and non-biodegradable medical devices with a 90Y beta emitter within glass spheres or adsorbed onto resin spheres. Tumor cells receive the blood supply predominantly through the arterial system compared to the normal liver tissue which receives supply from the portal venous system. This preferential flow facilitates selective delivery of the radioactive microspheres to the tumor during transcatheter arterial therapies [
The first step in the multidisciplinary approach is the planning or mapping angiogram phase that serves to confirm the normal or variant hepatic arterial anatomy and to coil embolize the GDA. Subsequently, Tc-99m MAA is injected to confirm lack of extrahepatic distribution and quantify the intrinsic tumoral lung shunting, which is used in conjunction with anatomical imaging volume and laboratory data for dose calculation. The treatment phase angiogram serves to reconfirm the arterial anatomy of the tumor, after which the 90Y microspheres are administered selectively up to the calculated dose or until flow stasis is achieved. A posttreatment Bremsstrahlung scan confirms dose delivery to tumor and absence of extrahepatic activity. These technical details and guidelines have been meticulously described previously [
Arterial variants and abnormalities in the mesenteric and hepatic circulations might require alternate techniques for safe and effective radioembolization [
Up to date, there have been a few case reports demonstrating the utilization of the SMA-inferior PDA approach for 90Y microsphere therapy in cases of celiac artery stenosis [
90Y microspheres radioembolization offers a unique opportunity to treat nonresectable, liver predominant hepatic malignancies with good tumor response, and overall progression free survival rates. Hepatic arterial variants and abnormalities such as arterial stenosis might limit access to the hepatic arterial branches supplying the tumor, and therefore, require alternate approaches or additional minimally invasive endovascular interventions. We report the use of stenting procedure in a case of celiac artery stenosis to facilitate hepatic 90Y microsphere radioembolization. This technique can be performed as a first line approach or in cases where the hepatic branches are not technically accessible through the conventional SMA-PDA arcade approach. Although the use of celiac axis stenting for 90Y microspheres radioembolization has been successful in our case, this approach should be evaluated further in a larger study population.
Technetium-99m macroaggregated albumin
Yttrium-90
Gastroduodenal artery
Superior mesenteric artery
Pancreaticoduodenal artery.