DOI: 10.1148/rg.273065036
RadioGraphics 2007;27:687-705
© RSNA, 2007
Inferior Phrenic Artery: Anatomy, Variations, Pathologic Conditions, and Interventional Management1
Dong Il Gwon, MD,
Gi-Young Ko, MD,
Hyun-Ki Yoon, MD,
Kyu-Bo Sung, MD,
Jae Moung Lee, MD,
Seok Jong Ryu, MD,
Myong Hee Seo, MD,
Jae-Chan Shim, MD,
Ghi Jai Lee, MD, and
Ho Kyun Kim, MD
1 From the Department of Radiology, Seoul Paik Hospital, University of Inje College of Medicine, Seoul, Korea (D.I.G., J.M.L., S.J.R., M.H.S., J.C.S., G.J.L., H.K.K.); and the Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-Dong, Songpa-Ku, Seoul 138-736, Korea (G.Y.K., H.K.Y., K.B.S.). Recipient of a Cum Laude award for an education exhibit at the 2005 RSNA Annual Meeting. Received March 22, 2006; revision requested June 12; final revision received January 18, 2007; accepted January 26. All authors have no financial relationships to disclose.
Address correspondence to G.Y.K. (e-mail: kogy{at}amc.seoul.kr).
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Abstract
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The inferior phrenic artery (IPA) is the most common source of extra-hepatic collateral blood supply for hepatocellular carcinoma (HCC) and frequently supplies HCCs located in the bare area of the liver. Other pathologic conditions including hemoptysis, diaphragmatic or hepatic bleeding due to trauma or surgery, and bleeding caused by gastroesophageal problems (eg, Mallory-Weiss tear or gastroesophageal cancer) may be related to the IPA. Over a 4-year period, the authors performed 383 interventional procedures related to the IPA. The right and left IPAs originate with almost equal frequency from the aorta and celiac axis and with lesser frequency from the renal arteries. Various other sites of origin—such as the left gastric, hepatic, superior mesenteric, spermatic, and adrenal arteries—are also seen. Radiologists must be familiar with the normal spectrum of IPA anatomy so that detection and adequate interventional management can be achieved when pathologic conditions related to the IPA are present.
© RSNA, 2007
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Introduction
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There are many pathologic conditions related to the inferior phrenic artery (IPA), the most common of which is extrahepatic collateral supply of hepatocellular carcinoma (HCC) (1–3). The development of extrahepatic collateral arteries that supply HCC interferes with effective control of the HCC by means of transcatheter arterial chemoembolization (TACE). To detect involvement of the IPA at an early stage, radiologists should be familiar with the spectrum of possible extrahepatic collateral supply by the IPA. The IPA can contribute to hemoptysis, especially when the pulmonary abnormality involves the lung base (4,5). Other pathologic conditions, such as diaphragmatic or hepatic bleeding due to trauma or surgery and bleeding resulting from gastroesophageal problems (eg, Mallory-Weiss tear and gastroesophageal cancer) may also be related to the IPA (6–9). In these cases, interventional management of the IPA should be attempted to increase therapeutic efficacy.
To effectively treat pathologic conditions related to the IPA, radiologists should be familiar both with the anatomy and variations of the normal IPA and with its imaging appearance at computed tomographic (CT) and conventional angiography. In this article, we discuss the anatomy and variations of the IPA, pathologic conditions related to the IPA, and interventional management of those conditions.
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Imaging Techniques and Interventional Methods
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From March 2001 to February 2005, 383 interventional procedures related to the IPA were performed at Seoul Paik Hospital and Asan Medical Center. All triple-phase dynamic CT scans were obtained with a multi–detector row helical CT unit (HiSpeed Advantage [GE Medical Systems, Milwaukee, Wis] or Somatom Plus [Siemens, Erlangen, Germany]). A 19–21-gauge intravenous catheter was placed in the patient’s antecubital vein, and 100 mL of nonionic contrast material was injected intravenously at a rate of 2.5 mL/sec by using a power injector. Triple-phase dynamic CT was performed at 30 seconds for the arterial phase, 60 seconds for the portal venous phase, and 180 seconds for the equilibrium phase. The images were obtained in a craniocaudal direction during a single breath-hold acquisition of 20–30 seconds, depending on the liver size, by using the following settings: 7-mm collimation, 10 mm/sec table speed, and 7–8-mm reconstruction interval.
CT during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) were used for preoperative evaluation of candidates for hepatic resection. For CTAP and CTHA, arterial vascular access was obtained through two separate punctures in the same femoral artery by using the Seldinger technique. Two 5-F Rösch hepatic catheters (Cook, Bloomington, Ind) were selectively placed, one in the superior mesenteric artery and the other in the common hepatic artery. Before CTAP and CTHA, celiac and superior mesenteric angiographic examinations were performed to evaluate tumor vascularity and the vascular anatomy. For CTAP, 80 mL of contrast material was injected through the superior mesenteric artery with a power injector at a rate of 2.5 mL/sec, and CT was performed 35 seconds after the start of injection. For CTHA, 36 mL of contrast material was injected through the common hepatic artery at a rate of 1.8 mL/sec, and CT was performed 6 seconds after the start of injection. The images were obtained in a craniocaudal direction during a single breath-hold acquisition of 20–30 seconds, depending on the liver size. The scanning parameters were the same as for triple-phase dynamic CT.
For TACE in patients with a hepatic tumor, superior mesenteric arterial portography and celiac angiography were performed first, followed by selective angiography of the proper hepatic, right hepatic, and left hepatic arteries; a digital subtraction angiography unit was used (V-3000 [Philips Medical Systems, Best, the Netherlands] or Multistar TOP [Siemens Medical Solutions, Forchheim, Germany]). IPA collateral supply of a hepatic tumor was suspected after analysis of the findings demonstrated a hepatic tumor abutting the bare area of the liver at initial CT, visualization of a hypertrophied IPA, a peripheral defect of iodized oil retention within the tumor at follow-up CT that was indicated by the previous TACE, a local recurrence at the peripheral portion of the treated tumor during follow-up, no definitive tumor staining or occlusion of the celiac or hepatic artery at routine angiography, and injury to the hepatic artery after multiple previous sessions of TACE.
In most cases, the IPA angiograms were obtained through a 5-F Rösch hepatic catheter with manual injection of 5–10 mL of contrast material. If adequate angiograms were not obtained through the 5-F catheter due to IPA orifice stenosis, superselective IPA angiograms were obtained through a 3-F microcatheter (SP [Terumo, Tokyo, Japan] or Microferret-18 [Cook]); 4–8 mL of contrast material was injected with a power injector at a rate of 2 mL/sec. Because the IPA orifice was previously identified with arterial phase dynamic CT, abdominal aortography was not performed. Although the IPA orifice was unclear at CT, the probable site of IPA origin can be deduced, so there was no need for abdominal aortography.
When an IPA angiogram showed tumor staining, treatment by way of the IPA was performed. A 3-F microcatheter was selectively inserted into the branches of the IPA supplying the liver tumor, and IPA embolization was performed. Because tissue toxic effects due to chemotherapeutic agents have the potential to cause complications, only a single use of chemotherapeutic agents for TACE through the IPA was avoided. Approximately 2–5 mL of iodized oil mixed with 4–10 mL of cis-diaminedichloroplatinum (cisplatin; Dong A, Seoul, Korea) or 5–10 mg of doxorubicin hydrochloride (Adriamycin; Dong A) was carefully injected until near stasis was observed, with careful observation for reflux into nontarget branches. A small amount of gelatin sponge (Spongostan; Johnson & Johnson, Skipton, England) was also used to achieve complete embolization of the IPA.
For all patients with hemoptysis, contrast-enhanced CT was performed because it is useful in diagnosing the underlying disease, localizing the bleeding site, and demonstrating the presence of nonbronchial systemic collateral vessels, which can be a significant source of recurrent hemoptysis after successful bronchial artery embolization. When treating patients with hemoptysis, the bronchial arteries were addressed first. In patients with lower lung pathologic conditions related to hemoptysis, an IPA angiogram was obtained (a) when CT or thoracic aortography after bronchial artery embolization revealed pleural thickening and a hypertrophied IPA within hypertrophied extrapleural fat or (b) when hemoptysis recurred after the previous bronchial artery embolization. These angiograms were obtained through a 5-F visceral catheter (Cobra; Cook). After the selective angiography, if the bronchial arteries and IPA were thought to be the source of hemoptysis, they were superselectively catheterized by using a 3-F microcatheter and then carefully embolized with 355–510-µm polyvinyl alcohol particles (Contour; Boston Scientific, Cork, Ireland), gelatin sponge, or microcoils (Tornado; Cook).
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Anatomy of the IPA and Variations
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The IPA usually originates between the middle of the 12th thoracic and second lumbar vertebrae (10). The right IPA and left IPA originate with almost equal frequency from the aorta (Figs 1, 2) and celiac axis (Fig 3c), either as a common trunk or independently. They arise with less frequency from the renal arteries (Fig 4c) and in rare cases from the left gastric (Fig 5), hepatic (Fig 6), superior mesenteric (Fig 7), and spermatic arteries (10–12). Occasionally, they arise from the contralateral IPA (Fig 8). The locations of IPA origin in our patient series and their frequency are listed in the Table.
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Figure 1a. Normal anatomy of a right IPA originating from the aorta in a 55-year-old man with a recurrent HCC in the right posterior superior hepatic lobe. (a) Arterial phase dynamic CT scan obtained after two sessions of TACE shows the right IPA (arrow) originating from the aorta. A recurrent HCC was seen in liver segment 7. (b) Selective right inferior phrenic angiogram obtained for treatment of the recurrent HCC by means of a 5-F Rösch hepatic catheter shows the normal anatomy of the right IPA, which originates from the aorta, as well as no definitive tumor staining. There was no tumor staining on a hepatic angiogram, and the viable portion of the HCC was supplied by the right 10th and 11th intercostal arteries. 1 = ascending (anterior) branch, 2 = descending (posterior) branch, 3 = inferior vena caval branch, 4 = superior adrenal branch, 5 = diaphragmatic branch.
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Figure 1b. Normal anatomy of a right IPA originating from the aorta in a 55-year-old man with a recurrent HCC in the right posterior superior hepatic lobe. (a) Arterial phase dynamic CT scan obtained after two sessions of TACE shows the right IPA (arrow) originating from the aorta. A recurrent HCC was seen in liver segment 7. (b) Selective right inferior phrenic angiogram obtained for treatment of the recurrent HCC by means of a 5-F Rösch hepatic catheter shows the normal anatomy of the right IPA, which originates from the aorta, as well as no definitive tumor staining. There was no tumor staining on a hepatic angiogram, and the viable portion of the HCC was supplied by the right 10th and 11th intercostal arteries. 1 = ascending (anterior) branch, 2 = descending (posterior) branch, 3 = inferior vena caval branch, 4 = superior adrenal branch, 5 = diaphragmatic branch.
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Figure 2a. Aortic origin of the replaced right hepatic artery and IPA as a common trunk in a 45-year-old man with an HCC in the right anterior hepatic lobe. (a) Arterial phase dynamic CT scan shows the common trunk (arrow) of the replaced right hepatic artery and IPAs originating from the aorta. At celiac angiography, the right hepatic artery was not seen and there was no definitive tumor staining. (b) Selective right hepatic arteriogram from the first session of TACE shows the common trunk (arrow) of the replaced right hepatic artery and IPAs. Note the tumor staining (*) from the replaced right hepatic artery. TACE of the tumor was successfully performed by superselectively inserting a 3-F microcatheter into the tumor feeding branches of the right anterior superior hepatic artery. 1 = anterior trunk of ascending branch, 2 = posterior trunk of ascending branch, 3 = gastric branch.
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Figure 2b. Aortic origin of the replaced right hepatic artery and IPA as a common trunk in a 45-year-old man with an HCC in the right anterior hepatic lobe. (a) Arterial phase dynamic CT scan shows the common trunk (arrow) of the replaced right hepatic artery and IPAs originating from the aorta. At celiac angiography, the right hepatic artery was not seen and there was no definitive tumor staining. (b) Selective right hepatic arteriogram from the first session of TACE shows the common trunk (arrow) of the replaced right hepatic artery and IPAs. Note the tumor staining (*) from the replaced right hepatic artery. TACE of the tumor was successfully performed by superselectively inserting a 3-F microcatheter into the tumor feeding branches of the right anterior superior hepatic artery. 1 = anterior trunk of ascending branch, 2 = posterior trunk of ascending branch, 3 = gastric branch.
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Figure 3a. HCC supplied by the right IPA in a 44-year-old man. (a) Arterial phase dynamic CT scan shows a huge mass (*) at the dome of the right hepatic lobe. (b) Selective common hepatic angiogram from the first session of TACE shows extensive hypervascular tumor staining. Note the wedge-shaped area without tumor staining (arrowhead) at the dome of the right hepatic lobe. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the celiac trunk, shows hypervascular tumor staining (arrowhead) that corresponds to the nonstained area on the common hepatic angiogram (b). (d) Radiograph obtained after embolization of the right hepatic artery and right IPA shows the HCC (*) compactly laden with Lipiodol (iodized oil; Guerbet, Roissy, France).
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Figure 3b. HCC supplied by the right IPA in a 44-year-old man. (a) Arterial phase dynamic CT scan shows a huge mass (*) at the dome of the right hepatic lobe. (b) Selective common hepatic angiogram from the first session of TACE shows extensive hypervascular tumor staining. Note the wedge-shaped area without tumor staining (arrowhead) at the dome of the right hepatic lobe. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the celiac trunk, shows hypervascular tumor staining (arrowhead) that corresponds to the nonstained area on the common hepatic angiogram (b). (d) Radiograph obtained after embolization of the right hepatic artery and right IPA shows the HCC (*) compactly laden with Lipiodol (iodized oil; Guerbet, Roissy, France).
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Figure 3c. HCC supplied by the right IPA in a 44-year-old man. (a) Arterial phase dynamic CT scan shows a huge mass (*) at the dome of the right hepatic lobe. (b) Selective common hepatic angiogram from the first session of TACE shows extensive hypervascular tumor staining. Note the wedge-shaped area without tumor staining (arrowhead) at the dome of the right hepatic lobe. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the celiac trunk, shows hypervascular tumor staining (arrowhead) that corresponds to the nonstained area on the common hepatic angiogram (b). (d) Radiograph obtained after embolization of the right hepatic artery and right IPA shows the HCC (*) compactly laden with Lipiodol (iodized oil; Guerbet, Roissy, France).
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Figure 3d. HCC supplied by the right IPA in a 44-year-old man. (a) Arterial phase dynamic CT scan shows a huge mass (*) at the dome of the right hepatic lobe. (b) Selective common hepatic angiogram from the first session of TACE shows extensive hypervascular tumor staining. Note the wedge-shaped area without tumor staining (arrowhead) at the dome of the right hepatic lobe. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the celiac trunk, shows hypervascular tumor staining (arrowhead) that corresponds to the nonstained area on the common hepatic angiogram (b). (d) Radiograph obtained after embolization of the right hepatic artery and right IPA shows the HCC (*) compactly laden with Lipiodol (iodized oil; Guerbet, Roissy, France).
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Figure 4a. HCC exclusively supplied by the right IPA in a 58-year-old man. (a) Arterial phase dynamic CT scan shows a hypervascular mass (*) in the posterior portion of the right hepatic lobe. Note the hypertrophied ascending portion of the right IPA (arrow). (b) Selective celiac angiogram from the first session of TACE shows no definitive tumor staining. We concluded that the feeding vessel might be the right IPA because of the tumor location directly adjacent to the posterior diaphragm, the hypertrophied right IPA, and the absence of tumor staining at celiac angiography. Dynamic CT showed that the right IPA originated from the right renal artery; therefore, aortography for detection of the right IPA was not performed. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the right renal artery, shows hypervascular tumor staining (*). The intercostal artery (arrowhead) arising from the right IPA is the feeding vessel for the HCC. (d) Radiograph obtained after embolization of the right IPA shows the compact HCC (*) laden with iodized oil.
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Figure 4b. HCC exclusively supplied by the right IPA in a 58-year-old man. (a) Arterial phase dynamic CT scan shows a hypervascular mass (*) in the posterior portion of the right hepatic lobe. Note the hypertrophied ascending portion of the right IPA (arrow). (b) Selective celiac angiogram from the first session of TACE shows no definitive tumor staining. We concluded that the feeding vessel might be the right IPA because of the tumor location directly adjacent to the posterior diaphragm, the hypertrophied right IPA, and the absence of tumor staining at celiac angiography. Dynamic CT showed that the right IPA originated from the right renal artery; therefore, aortography for detection of the right IPA was not performed. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the right renal artery, shows hypervascular tumor staining (*). The intercostal artery (arrowhead) arising from the right IPA is the feeding vessel for the HCC. (d) Radiograph obtained after embolization of the right IPA shows the compact HCC (*) laden with iodized oil.
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Figure 4c. HCC exclusively supplied by the right IPA in a 58-year-old man. (a) Arterial phase dynamic CT scan shows a hypervascular mass (*) in the posterior portion of the right hepatic lobe. Note the hypertrophied ascending portion of the right IPA (arrow). (b) Selective celiac angiogram from the first session of TACE shows no definitive tumor staining. We concluded that the feeding vessel might be the right IPA because of the tumor location directly adjacent to the posterior diaphragm, the hypertrophied right IPA, and the absence of tumor staining at celiac angiography. Dynamic CT showed that the right IPA originated from the right renal artery; therefore, aortography for detection of the right IPA was not performed. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the right renal artery, shows hypervascular tumor staining (*). The intercostal artery (arrowhead) arising from the right IPA is the feeding vessel for the HCC. (d) Radiograph obtained after embolization of the right IPA shows the compact HCC (*) laden with iodized oil.
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Figure 4d. HCC exclusively supplied by the right IPA in a 58-year-old man. (a) Arterial phase dynamic CT scan shows a hypervascular mass (*) in the posterior portion of the right hepatic lobe. Note the hypertrophied ascending portion of the right IPA (arrow). (b) Selective celiac angiogram from the first session of TACE shows no definitive tumor staining. We concluded that the feeding vessel might be the right IPA because of the tumor location directly adjacent to the posterior diaphragm, the hypertrophied right IPA, and the absence of tumor staining at celiac angiography. Dynamic CT showed that the right IPA originated from the right renal artery; therefore, aortography for detection of the right IPA was not performed. (c) Selective angiogram obtained via the right IPA (arrow), which originates from the right renal artery, shows hypervascular tumor staining (*). The intercostal artery (arrowhead) arising from the right IPA is the feeding vessel for the HCC. (d) Radiograph obtained after embolization of the right IPA shows the compact HCC (*) laden with iodized oil.
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Figure 5a. Right IPA originating from the left gastric artery in a 47-year-old woman. (a) Arterial phase dynamic CT scan shows the right IPA (arrow) originating from the left gastrohepatic trunk (arrowhead). (b) Selective angiogram obtained via the gastrohepatic trunk (arrowhead) shows the right IPA (black arrow) and the replaced left hepatic artery (white arrow). Note the tumor staining (*) from the replaced left hepatic artery.
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Figure 5b. Right IPA originating from the left gastric artery in a 47-year-old woman. (a) Arterial phase dynamic CT scan shows the right IPA (arrow) originating from the left gastrohepatic trunk (arrowhead). (b) Selective angiogram obtained via the gastrohepatic trunk (arrowhead) shows the right IPA (black arrow) and the replaced left hepatic artery (white arrow). Note the tumor staining (*) from the replaced left hepatic artery.
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Figure 6a. Left IPA originating from the proper hepatic artery in a 42-year-old woman with a dysplastic nodule in the right anterior inferior hepatic lobe. (a) Selective common hepatic angiogram shows the left IPA (arrow) originating from the proper hepatic artery and no definitive tumor staining. Note the accessory left gastric artery (arrowhead) arising from the left IPA and the gastric staining (*). 1 = anterior trunk of ascending branch of the left IPA, 2 = posterior trunk of ascending branch of the left IPA. (b) CTHA image obtained for evaluation of the dysplastic nodule shows the left IPA (arrow) and accessory left gastric artery (arrowhead). Note the gastric staining (*).
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Figure 6b. Left IPA originating from the proper hepatic artery in a 42-year-old woman with a dysplastic nodule in the right anterior inferior hepatic lobe. (a) Selective common hepatic angiogram shows the left IPA (arrow) originating from the proper hepatic artery and no definitive tumor staining. Note the accessory left gastric artery (arrowhead) arising from the left IPA and the gastric staining (*). 1 = anterior trunk of ascending branch of the left IPA, 2 = posterior trunk of ascending branch of the left IPA. (b) CTHA image obtained for evaluation of the dysplastic nodule shows the left IPA (arrow) and accessory left gastric artery (arrowhead). Note the gastric staining (*).
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Figure 7a. Right IPA originating from the superior mesenteric artery and supplying a huge HCC in a 49-year-old woman. (a) Arterial phase dynamic CT scan shows the right IPA (arrow) originating from the superior mesenteric artery (arrowhead). (b) Arterial phase dynamic CT scan obtained at a higher level shows a huge HCC (*) at the dome of the right hepatic lobe. Note the hypertrophied right IPA (arrow). (c) Selective superior mesenteric angiogram from the first session of TACE shows hypervascular tumor staining (*) from the right IPA (arrow), which originates from the superior mesenteric artery (arrowhead). Celiac angiography showed the huge hypervascular tumor with faint tumor staining, which corresponded to the hypervascular tumor staining seen on the superior mesenteric angiogram, in the right superior portion of the liver.
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Figure 7b. Right IPA originating from the superior mesenteric artery and supplying a huge HCC in a 49-year-old woman. (a) Arterial phase dynamic CT scan shows the right IPA (arrow) originating from the superior mesenteric artery (arrowhead). (b) Arterial phase dynamic CT scan obtained at a higher level shows a huge HCC (*) at the dome of the right hepatic lobe. Note the hypertrophied right IPA (arrow). (c) Selective superior mesenteric angiogram from the first session of TACE shows hypervascular tumor staining (*) from the right IPA (arrow), which originates from the superior mesenteric artery (arrowhead). Celiac angiography showed the huge hypervascular tumor with faint tumor staining, which corresponded to the hypervascular tumor staining seen on the superior mesenteric angiogram, in the right superior portion of the liver.
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Figure 7c. Right IPA originating from the superior mesenteric artery and supplying a huge HCC in a 49-year-old woman. (a) Arterial phase dynamic CT scan shows the right IPA (arrow) originating from the superior mesenteric artery (arrowhead). (b) Arterial phase dynamic CT scan obtained at a higher level shows a huge HCC (*) at the dome of the right hepatic lobe. Note the hypertrophied right IPA (arrow). (c) Selective superior mesenteric angiogram from the first session of TACE shows hypervascular tumor staining (*) from the right IPA (arrow), which originates from the superior mesenteric artery (arrowhead). Celiac angiography showed the huge hypervascular tumor with faint tumor staining, which corresponded to the hypervascular tumor staining seen on the superior mesenteric angiogram, in the right superior portion of the liver.
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Figure 8a. Left IPA originating from the right IPA in a 49-year-old woman who had undergone S6 segmentectomy. (a) Arterial phase dynamic CT scan obtained after the second session of postoperative TACE shows a recurrent tumor (*) at the resection margin. Note the right IPA (arrow), which originates from the celiac axis. (b) Selective angiogram obtained via the right IPA (black arrow) shows the left IPA (arrowhead) originating from the right IPA. Note the esophageal branch (white arrow) of the left IPA and the tumor staining (*).
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Figure 8b. Left IPA originating from the right IPA in a 49-year-old woman who had undergone S6 segmentectomy. (a) Arterial phase dynamic CT scan obtained after the second session of postoperative TACE shows a recurrent tumor (*) at the resection margin. Note the right IPA (arrow), which originates from the celiac axis. (b) Selective angiogram obtained via the right IPA (black arrow) shows the left IPA (arrowhead) originating from the right IPA. Note the esophageal branch (white arrow) of the left IPA and the tumor staining (*).
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The IPA is easily recognized on dynamic CT scans because it ascends through abundant retroperitoneal fat on a diaphragmatic crus (Fig 4a), with a course vertical to the axial planes of CT images (12,13). The origin of the IPA can be ascertained easily in most cases, but occasionally determination of the origin of the IPA is difficult when it runs parallel to the axial CT plane at that point. Atherosclerotic change can contribute to this difficulty because calcified plaques can overlap the origin of the IPA (12).
The right and left IPAs give rise to ascending (anterior), descending (posterior), superior suprarenal, and middle suprarenal branches. The ascending branch of the right IPA gives rise to inferior vena caval and diaphragmatic branches, and the ascending branch of the left IPA gives rise to esophageal and accessory splenic branches (Figs 1b, 2b, 6a, 8b) (11). The angiographic appearance of the IPA is peculiar. It branches into several superior adrenal arteries during its cranial ascent along the spine, then divides into ascending and descending branches under the diaphragm (12,14,15).
The ascending branch is usually located cranially and contacts the bare area of the liver, where no parietal peritoneum covers the diaphragm. Liver segments 1, 2, and 7 make up the bare area (1,2,12,14). As the ascending branch passes behind the inferior vena cava, it shoots off the inferior vena caval and diaphragmatic hiatal branches (Fig 1b) (11). Potentially, the IPA can communicate with the internal mammary artery, intercostal artery (Fig 4c), musculophrenic artery, pericardiophrenic artery (Fig 9c), and other systemic vessels of the thorax (10,14). The descending branch courses toward the lateral crus and anastomoses with the lower posterior intercostal arteries and musculophrenic artery.
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Figure 9a. Hemoptysis due to right middle lobe collapse with bronchiectasis in a 66-year-old woman. (a) Contrast-enhanced chest CT scan obtained at the level of the celiac trunk shows the right IPA (arrows) originating from the aorta. (b) Contrast-enhanced chest CT scan obtained at a higher level shows collapse of the right middle lobe (*). Note the hypertrophied vascular structure (arrow) near the right atrium. (c) Selective right inferior phrenic angiogram shows pulmonary arterial shunts (arrowheads) supplied by the hypertrophied pericardiophrenic artery (white arrow), which originates from the right IPA (black arrow).
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Figure 9b. Hemoptysis due to right middle lobe collapse with bronchiectasis in a 66-year-old woman. (a) Contrast-enhanced chest CT scan obtained at the level of the celiac trunk shows the right IPA (arrows) originating from the aorta. (b) Contrast-enhanced chest CT scan obtained at a higher level shows collapse of the right middle lobe (*). Note the hypertrophied vascular structure (arrow) near the right atrium. (c) Selective right inferior phrenic angiogram shows pulmonary arterial shunts (arrowheads) supplied by the hypertrophied pericardiophrenic artery (white arrow), which originates from the right IPA (black arrow).
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Figure 9c. Hemoptysis due to right middle lobe collapse with bronchiectasis in a 66-year-old woman. (a) Contrast-enhanced chest CT scan obtained at the level of the celiac trunk shows the right IPA (arrows) originating from the aorta. (b) Contrast-enhanced chest CT scan obtained at a higher level shows collapse of the right middle lobe (*). Note the hypertrophied vascular structure (arrow) near the right atrium. (c) Selective right inferior phrenic angiogram shows pulmonary arterial shunts (arrowheads) supplied by the hypertrophied pericardiophrenic artery (white arrow), which originates from the right IPA (black arrow).
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Behind the esophagus, the ascending branch of the left IPA divides into a larger anterior trunk and smaller posterior trunk (Figs 2b, 6a). The anterior trunk supplies the dome of the diaphragm and the region of the esophagogastric junction. The left IPA may give rise to a small number of branches that serve to supply the superior pole of the spleen and the proximal portion of the stomach (Figs 2b, 6a, 8b) (11).
The right IPA potentially communicates with the intrahepatic arteries. Among the various collateral pathways, one of the most common sources of extrahepatic blood supply to the liver is the right IPA (15,16). All liver segments have the potential for such communication, but it typically occurs with the caudate lobe and posterior segment, whereas the frequency of communication with the other segments is lower (16). In cases of occlusion or severe stenosis of hepatic arteries after repeated TACE, the hepatic arteries are mainly reconstituted through the right IPA (Fig 10).
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Figure 10a. HCCs supplied by the right hepatic artery, right IPA, and reconstituted right posterior hepatic artery through the right IPA in a 63-year-old woman who had undergone six sessions of TACE. (a) Selective celiac angiogram from the seventh session of TACE shows severe injury to the proper hepatic artery and intra-hepatic arteries (arrowheads) due to previous TACE. Note the tumor staining (*) in the right hepatic lobe. (b) Selective right inferior phrenic angiogram shows that the right posterior hepatic artery (arrow) is reconstituted through the right IPA. Note the HCCs (*) supplied by the right IPA and reconstituted right posterior hepatic artery.
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Figure 10b. HCCs supplied by the right hepatic artery, right IPA, and reconstituted right posterior hepatic artery through the right IPA in a 63-year-old woman who had undergone six sessions of TACE. (a) Selective celiac angiogram from the seventh session of TACE shows severe injury to the proper hepatic artery and intra-hepatic arteries (arrowheads) due to previous TACE. Note the tumor staining (*) in the right hepatic lobe. (b) Selective right inferior phrenic angiogram shows that the right posterior hepatic artery (arrow) is reconstituted through the right IPA. Note the HCCs (*) supplied by the right IPA and reconstituted right posterior hepatic artery.
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The left IPA has the potential to communicate with intrahepatic arteries of the lateral segment (15). When the IPA is occluded, it is likely to be reconstituted through retroperitoneal branches derived from the dorsal pancreatic artery, adrenal arteries (Fig 11), left gastric artery, and patent contralateral IPA (17). Possible collateral pathways are sometimes missed in cases of occlusion or stenosis of the hepatic arteries or IPA. Therefore, potential collateral pathways of the IPA and hepatic artery should be kept in mind in order to accomplish effective interventional management.
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Figure 11a. IPA reconstituted through the right middle adrenal artery in a 47-year-old man with celiac artery occlusion. (a) Arterial phase dynamic CT scan shows a hypertrophied median arcuate ligament of the right diaphragmatic crus (arrowhead) and resultant occlusion of the celiac artery (arrow). (b) Selective angiogram obtained via the right middle adrenal artery (white arrow) shows the reconstituted IPA (black arrow), which is supplied by middle-superior adrenal collateral vessels (arrowheads).
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Figure 11b. IPA reconstituted through the right middle adrenal artery in a 47-year-old man with celiac artery occlusion. (a) Arterial phase dynamic CT scan shows a hypertrophied median arcuate ligament of the right diaphragmatic crus (arrowhead) and resultant occlusion of the celiac artery (arrow). (b) Selective angiogram obtained via the right middle adrenal artery (white arrow) shows the reconstituted IPA (black arrow), which is supplied by middle-superior adrenal collateral vessels (arrowheads).
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Pathologic Conditions Related to the IPA
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In 383 interventional procedures we performed related to the IPA, we observed 346 HCCs, which had extrahepatic collateral supplies from the IPA. Adrenal metastases and retroperitoneal seeding metastases related to the IPA were found and embolized in five cases. The importance of the IPA is not limited to treatment of HCC, however, as many other pathologic conditions may involve blood supply from the IPA. Other pathologic conditions related to the IPA that we treated included 19 cases of hemoptysis, 12 of postoperative bleeding, and one of trauma. In addition, there have been reports of gastric hemorrhage and Mallory-Weiss tear due to bleeding from the left IPA (7).
Extrahepatic Collateral Supply of HCC
TACE is an accepted method of treatment for patients considered to have unresectable disease. Recognition of the presence of extrahepatic collateral arteries is crucial for effective TACE because adequate embolization of both collateral arteries and the hepatic arteries is equally important. Among the collateral arteries, the IPA is the most frequently encountered (1–3). The IPA supplies most of the diaphragm along the course of its undersurface. Because the liver is suspended from the diaphragm by the coronary and triangular ligaments and because there is close contact between the posterior portion of the liver and the diaphragm at the bare area, the branches of the IPA may communicate with those of the hepatic arteries (1,2). When an HCC is located in liver segment 1 (Fig 12), 2, or 7 (Fig 3) and is in contact with the right hemidiaphragm, selective angiography of the right IPA is mandatory.
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Figure 12a. HCC in liver segment 1 supplied by the right IPA in a 56-year-old man with multinodular HCC in the entire liver. (a) Arterial phase dynamic CT scan shows multiple HCCs in the entire liver. Note the large HCC in liver segment 1 (*). (b) Arterial phase dynamic CT scan obtained after one session of TACE shows a recurrent tumor (arrowhead) in liver segment 1. Note the hypertrophied right IPA (arrow). (c) Selective angiogram obtained via the right IPA (arrow) shows hypervascular tumor staining (arrowhead) that corresponds to the recurrent tumor. (d) Precontrast CT scan obtained after two sessions of TACE shows the atrophied HCC (arrowhead) laden with iodized oil in liver segment 1.
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Figure 12b. HCC in liver segment 1 supplied by the right IPA in a 56-year-old man with multinodular HCC in the entire liver. (a) Arterial phase dynamic CT scan shows multiple HCCs in the entire liver. Note the large HCC in liver segment 1 (*). (b) Arterial phase dynamic CT scan obtained after one session of TACE shows a recurrent tumor (arrowhead) in liver segment 1. Note the hypertrophied right IPA (arrow). (c) Selective angiogram obtained via the right IPA (arrow) shows hypervascular tumor staining (arrowhead) that corresponds to the recurrent tumor. (d) Precontrast CT scan obtained after two sessions of TACE shows the atrophied HCC (arrowhead) laden with iodized oil in liver segment 1.
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Figure 12c. HCC in liver segment 1 supplied by the right IPA in a 56-year-old man with multinodular HCC in the entire liver. (a) Arterial phase dynamic CT scan shows multiple HCCs in the entire liver. Note the large HCC in liver segment 1 (*). (b) Arterial phase dynamic CT scan obtained after one session of TACE shows a recurrent tumor (arrowhead) in liver segment 1. Note the hypertrophied right IPA (arrow). (c) Selective angiogram obtained via the right IPA (arrow) shows hypervascular tumor staining (arrowhead) that corresponds to the recurrent tumor. (d) Precontrast CT scan obtained after two sessions of TACE shows the atrophied HCC (arrowhead) laden with iodized oil in liver segment 1.
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Figure 12d. HCC in liver segment 1 supplied by the right IPA in a 56-year-old man with multinodular HCC in the entire liver. (a) Arterial phase dynamic CT scan shows multiple HCCs in the entire liver. Note the large HCC in liver segment 1 (*). (b) Arterial phase dynamic CT scan obtained after one session of TACE shows a recurrent tumor (arrowhead) in liver segment 1. Note the hypertrophied right IPA (arrow). (c) Selective angiogram obtained via the right IPA (arrow) shows hypervascular tumor staining (arrowhead) that corresponds to the recurrent tumor. (d) Precontrast CT scan obtained after two sessions of TACE shows the atrophied HCC (arrowhead) laden with iodized oil in liver segment 1.
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The hypertrophied ascending portion of the IPA can be easily recognized on arterial phase CT scans (Figs 4a, 7b, 12b, 13a). Visualization of the distal portion of the IPA as it enters the liver surface (Fig 13b), especially in HCCs located on the liver surface, is a predictive CT finding of extra-hepatic collateral supply to the HCC by the IPA (13). The diameter of the right IPA is larger than that of the left IPA in patients with HCCs fed by the right IPA. A right IPA dilated to more than 2.5 mm is predictive of a parasitic supply (11,13). However, previous studies indicated that the normal diameter of the right IPA and left IPA is 2.2 mm (range, 1.4–3.2 mm) and 2.0 mm (range, 1.4–2.8 mm), respectively. Therefore, mere predominance of the right IPA is not a certain predictor of extrahepatic collateral supply because the right IPA can also be predominant in the normal population (13).
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Figure 13a. Huge HCC supplied by the left IPA in a 38-year-old man. (a) Arterial phase dynamic CT scan shows a hypertrophied left IPA (arrow). Note the huge HCC (*) in the left hepatic lobe. (b) Arterial phase dynamic CT scan obtained at the level of the hepatic dome shows the distal portion of the left IPA (arrowheads) supplying the HCC. (c) Selective inferior phrenic angiogram shows the hypertrophied left IPA (arrow) supplying the dome area of the HCC.
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Figure 13b. Huge HCC supplied by the left IPA in a 38-year-old man. (a) Arterial phase dynamic CT scan shows a hypertrophied left IPA (arrow). Note the huge HCC (*) in the left hepatic lobe. (b) Arterial phase dynamic CT scan obtained at the level of the hepatic dome shows the distal portion of the left IPA (arrowheads) supplying the HCC. (c) Selective inferior phrenic angiogram shows the hypertrophied left IPA (arrow) supplying the dome area of the HCC.
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Figure 13c. Huge HCC supplied by the left IPA in a 38-year-old man. (a) Arterial phase dynamic CT scan shows a hypertrophied left IPA (arrow). Note the huge HCC (*) in the left hepatic lobe. (b) Arterial phase dynamic CT scan obtained at the level of the hepatic dome shows the distal portion of the left IPA (arrowheads) supplying the HCC. (c) Selective inferior phrenic angiogram shows the hypertrophied left IPA (arrow) supplying the dome area of the HCC.
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Regardless of the patency of the hepatic artery, when an HCC is located in the left hepatic lobe and abuts the left hemidiaphragm, the possibility of a collateral supply from the left IPA (Figs 13, 14) should be borne in mind (2,3). The left IPA may become a collateral pathway to an HCC at the right dome area if the anterior branch of the right IPA is obstructed, as the IPAs anastomose with each other and provide a common blood supply to the bare areas of the liver and diaphragm (18).
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Figure 14a. HCC supplied by the left IPA in a 41-year-old man. (a) Arterial phase dynamic CT scan shows three enhancing masses in the liver. (b) Selective celiac angiogram shows three areas of tumor staining in the liver. Note the faint tumor staining in the superior portion (arrowheads) of one HCC. (c) Selective inferior phrenic angiogram shows hypervascular tumor staining (arrowheads) from the left IPA (arrows) that corresponds to the faint staining seen on the celiac angiogram.
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Figure 14b. HCC supplied by the left IPA in a 41-year-old man. (a) Arterial phase dynamic CT scan shows three enhancing masses in the liver. (b) Selective celiac angiogram shows three areas of tumor staining in the liver. Note the faint tumor staining in the superior portion (arrowheads) of one HCC. (c) Selective inferior phrenic angiogram shows hypervascular tumor staining (arrowheads) from the left IPA (arrows) that corresponds to the faint staining seen on the celiac angiogram.
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Figure 14c. HCC supplied by the left IPA in a 41-year-old man. (a) Arterial phase dynamic CT scan shows three enhancing masses in the liver. (b) Selective celiac angiogram shows three areas of tumor staining in the liver. Note the faint tumor staining in the superior portion (arrowheads) of one HCC. (c) Selective inferior phrenic angiogram shows hypervascular tumor staining (arrowheads) from the left IPA (arrows) that corresponds to the faint staining seen on the celiac angiogram.
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The IPA can be one of the systemic arteries that contribute to transpleural systemic-pulmonary artery anastomosis, especially when the pulmonary abnormality involves the lung base (4,5,19). Not infrequently, IPA imaging performed for suspected parasitization of the HCC reveals abnormal pulmonary staining that has no relationship to the HCC. This is a vascular blush caused by transpleural systemic-pulmonary arterial anastomosis (5). This pleural and pulmonary staining from the IPA is a benign condition that can be found in patients with chronic pleural and/or pulmonary inflammation, and it is relatively simple to differentiate it from tumor staining because of the characteristic pleural and pulmonary staining with visualization of the lower lung margin and draining pulmonary vein (Figs 15, 16b). If these findings are present, there is no need for IPA embolization, even when the artery is hypertrophied (19).
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Figure 15a. HCC supplied by the right IPA in a 65-year-old man. Pleural and pulmonary staining was noted at initial TACE. (a) Arterial phase image from right inferior phrenic angiography shows pleural and pulmonary staining (arrowheads). (b) Image from the late arterial phase shows the draining pulmonary veins (arrows) running along their courses into the left atrium. HCC staining (*) is also seen.
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Figure 15b. HCC supplied by the right IPA in a 65-year-old man. Pleural and pulmonary staining was noted at initial TACE. (a) Arterial phase image from right inferior phrenic angiography shows pleural and pulmonary staining (arrowheads). (b) Image from the late arterial phase shows the draining pulmonary veins (arrows) running along their courses into the left atrium. HCC staining (*) is also seen.
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Figure 16a. Retroperitoneal HCC seeding metastases supplied by the right IPA in a 46-year-old man who had undergone left lobectomy. (a) Arterial phase dynamic CT scan shows multiple seeding metastatic nodules (arrowheads) in the right retroperitoneal area. A left adrenal metastasis is also seen. (b) Selective right inferior phrenic angiogram shows hypervascular seeding metastases (arrowheads). Note the localized pleural and pulmonary staining (arrows) at the lateral aspect of the right lower lung base.
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Figure 16b. Retroperitoneal HCC seeding metastases supplied by the right IPA in a 46-year-old man who had undergone left lobectomy. (a) Arterial phase dynamic CT scan shows multiple seeding metastatic nodules (arrowheads) in the right retroperitoneal area. A left adrenal metastasis is also seen. (b) Selective right inferior phrenic angiogram shows hypervascular seeding metastases (arrowheads). Note the localized pleural and pulmonary staining (arrows) at the lateral aspect of the right lower lung base.
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In 346 cases of extrahepatic collateral supply from the IPA, we found three HCCs that were exclusively supplied by the right IPA (Figs 4, 17). These HCCs were located in liver segments 6 and 7, and two of them had not been previously treated. Recurrent HCCs previously treated with TACE may show delayed enhancement at dynamic CT when the hepatic artery is occluded and when long narrow extrahepatic collaterals other than the right IPA feed the HCC (20). However, in one case we found an HCC exclusively supplied by the IPA that also showed delayed enhancement at dynamic CT (Fig 17a, 17b). At CTHA and CTAP, these masses did not enhance at all (Fig 17c, 17d). Selective common hepatic angiography showed no tumor staining, a finding indicative of extrahepatic collateral supply (Fig 17e). In this case, we suggest that the right IPA had an accessory right hepatic artery that acted as the feeder for the HCC (Fig 17e). Other HCC-related pathologic conditions such as retroperitoneal seeding metastases (Fig 16) and adrenal metastases can also receive a blood supply from the IPA.
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Figure 17a. HCC exclusively supplied by the right IPA in a 40-year-old man. (a) Arterial phase dynamic CT scan shows a mass (*) in the posterior portion of the right hepatic lobe. The mass demonstrates peripheral nodular enhancement. (b) Portal phase dynamic CT scan shows gradual centripetal enhancement. (c, d) CTHA (c) and CTAP (d) images show no tumor enhancement. (e) Selective angiogram obtained via the right IPA shows hypervascular tumor staining (*). There was no tumor staining at hepatic angiography. On the CT scans, a vascular structure (arrowhead in a–d) is seen just posteromedial to the mass. The arrow in e indicates the vascular structure seen on the CT scans.
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Figure 17b. HCC exclusively supplied by the right IPA in a 40-year-old man. (a) Arterial phase dynamic CT scan shows a mass (*) in the posterior portion of the right hepatic lobe. The mass demonstrates peripheral nodular enhancement. (b) Portal phase dynamic CT scan shows gradual centripetal enhancement. (c, d) CTHA (c) and CTAP (d) images show no tumor enhancement. (e) Selective angiogram obtained via the right IPA shows hypervascular tumor staining (*). There was no tumor staining at hepatic angiography. On the CT scans, a vascular structure (arrowhead in a–d) is seen just posteromedial to the mass. The arrow in e indicates the vascular structure seen on the CT scans.
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Figure 17c. HCC exclusively supplied by the right IPA in a 40-year-old man. (a) Arterial phase dynamic CT scan shows a mass (*) in the posterior portion of the right hepatic lobe. The mass demonstrates peripheral nodular enhancement. (b) Portal phase dynamic CT scan shows gradual centripetal enhancement. (c, d) CTHA (c) and CTAP (d) images show no tumor enhancement. (e) Selective angiogram obtained via the right IPA shows hypervascular tumor staining (*). There was no tumor staining at hepatic angiography. On the CT scans, a vascular structure (arrowhead in a–d) is seen just posteromedial to the mass. The arrow in e indicates the vascular structure seen on the CT scans.
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Figure 17d. HCC exclusively supplied by the right IPA in a 40-year-old man. (a) Arterial phase dynamic CT scan shows a mass (*) in the posterior portion of the right hepatic lobe. The mass demonstrates peripheral nodular enhancement. (b) Portal phase dynamic CT scan shows gradual centripetal enhancement. (c, d) CTHA (c) and CTAP (d) images show no tumor enhancement. (e) Selective angiogram obtained via the right IPA shows hypervascular tumor staining (*). There was no tumor staining at hepatic angiography. On the CT scans, a vascular structure (arrowhead in a–d) is seen just posteromedial to the mass. The arrow in e indicates the vascular structure seen on the CT scans.
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Figure 17e. HCC exclusively supplied by the right IPA in a 40-year-old man. (a) Arterial phase dynamic CT scan shows a mass (*) in the posterior portion of the right hepatic lobe. The mass demonstrates peripheral nodular enhancement. (b) Portal phase dynamic CT scan shows gradual centripetal enhancement. (c, d) CTHA (c) and CTAP (d) images show no tumor enhancement. (e) Selective angiogram obtained via the right IPA shows hypervascular tumor staining (*). There was no tumor staining at hepatic angiography. On the CT scans, a vascular structure (arrowhead in a–d) is seen just posteromedial to the mass. The arrow in e indicates the vascular structure seen on the CT scans.
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Other Pathologic Conditions Involving the IPA
In patients with hemoptysis, the bronchial arteries are the primary source of bleeding. Reduced pulmonary circulation in the lesions of inflammatory lung disease leads to systemic-pulmonary arterial anastomosis accompanied by a compensatory increase in systemic circulation, resulting in rupture of systemic arteries. In addition to the bronchial arteries, many systemic arteries—such as the inferior phrenic, intercostal, thyrocervical, internal mammary, thoracodorsal, and lateral thoracic arteries—serve as nonbronchial systemic collaterals that also contribute to hemoptysis (4,5). Diseases associated with pleural fibrosis and decreased pulmonary blood flow, such as bronchiectasis, cystic fibrosis, tuberculosis, sarcoidosis, chronic pneumonia, congenital pulmonary artery stenosis, and in some cases pulmonary embolism, have a tendency to develop this kind of transpleural systemic-pulmonary artery anastomosis (4,19). The IPA and other nonbronchial systemic collaterals are consequently assumed to reduce the therapeutic effect of embolization (5). Therefore, it is important to recognize the IPA during transarterial embolization in patients with hemoptysis, especially when the pulmonary abnormality involves the lung base (Fig 18).
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Figure 18a. Hemoptysis due to cystic bronchiectasis in a 62-year-old man. (a) High-resolution chest CT scan shows cystic bronchiectasis (arrowheads) in the basal segment of the left lower lobe. Ground-glass opacities (*) in the right lower lobe indicate aspirated blood. (b) Contrast-enhanced chest CT scan shows a hypertrophied left IPA (arrow). (c) Selective angiogram obtained via the left IPA (arrow), which originates from the celiac trunk, shows pulmonary staining and draining pulmonary veins (arrowheads). Successful embolization of the bronchial arteries and left IPA with polyvinyl alcohol particles was performed. The patient had no further hemoptysis.
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Figure 18b. Hemoptysis due to cystic bronchiectasis in a 62-year-old man. (a) High-resolution chest CT scan shows cystic bronchiectasis (arrowheads) in the basal segment of the left lower lobe. Ground-glass opacities (*) in the right lower lobe indicate aspirated blood. (b) Contrast-enhanced chest CT scan shows a hypertrophied left IPA (arrow). (c) Selective angiogram obtained via the left IPA (arrow), which originates from the celiac trunk, shows pulmonary staining and draining pulmonary veins (arrowheads). Successful embolization of the bronchial arteries and left IPA with polyvinyl alcohol particles was performed. The patient had no further hemoptysis.
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Figure 18c. Hemoptysis due to cystic bronchiectasis in a 62-year-old man. (a) High-resolution chest CT scan shows cystic bronchiectasis (arrowheads) in the basal segment of the left lower lobe. Ground-glass opacities (*) in the right lower lobe indicate aspirated blood. (b) Contrast-enhanced chest CT scan shows a hypertrophied left IPA (arrow). (c) Selective angiogram obtained via the left IPA (arrow), which originates from the celiac trunk, shows pulmonary staining and draining pulmonary veins (arrowheads). Successful embolization of the bronchial arteries and left IPA with polyvinyl alcohol particles was performed. The patient had no further hemoptysis.
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Other pathologic conditions, such as diaphragmatic or hepatic bleeding due to trauma or surgery (Fig 19), may be related to the IPA (6,9). During liver transplantation, ligation of the right IPA is necessary for hepatectomy in the recipient and for right hepatic lobectomy in a living donor. If the ligation of this artery is not maintained adequately, bleeding from the IPA can occur after liver transplantation. Right IPA bleeding frequently occurs within the first 2 weeks after liver transplantation, especially in recipients who undergo living donor transplantation because of liver cirrhosis or HCC (9). In such cases, it is important to keep in mind the possibility of IPA bleeding, and careful evaluation of CT scans may be helpful in locating the origin of the IPA and active bleeding foci.
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Figure 19a. Bleeding after living donor liver transplantation in a 44-year-old woman. (a) Portal phase dynamic CT scan shows a perihepatic hematoma and two highly enhancing nodules (arrows) along the course of the right IPA. (b) Selective angiogram obtained via the right IPA shows a pseudoaneurysm with extravasation (arrow). Successful embolization of the right IPA with microcoils was performed.
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Figure 19b. Bleeding after living donor liver transplantation in a 44-year-old woman. (a) Portal phase dynamic CT scan shows a perihepatic hematoma and two highly enhancing nodules (arrows) along the course of the right IPA. (b) Selective angiogram obtained via the right IPA shows a pseudoaneurysm with extravasation (arrow). Successful embolization of the right IPA with microcoils was performed.
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In addition, there have been reports of gastro-esophageal hemorrhage and Mallory-Weiss tear due to bleeding from the left IPA (7,8). In cases of upper gastrointestinal bleeding, the IPA should be studied if no bleeding source is seen at routine angiography—such as the left gastric, celiac, or splenic artery—especially if a distal esophageal or proximal gastric lesion is suspected. These are good examples that highlight the necessity for a thorough knowledge of the blood supply to the gastroesophageal junction as supplied by the left IPA.
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Complications from IPA Interventions
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When the IPA is embolized, there is a risk of embolizing nontarget branches, which can lead to a variety of complications. Shoulder pain can develop during and immediately after IPA embolization, usually within a few days (1,2). Generally, neurons that supply the area in which the pain is felt enter the same segment of the spinal cord as do the neurons that actually conduct the pain stimuli from the visceral structure. After interventional management of the IPA, consequent irritation of the diaphragm returns a stimulus to the C3–C5 spinal levels, presumably via the phrenic nerve. The C3–C5 spinal level is the ancestral level of origin of the diaphragm muscle, and its segmental nervous innervation originates from there. Thus, the perceived shoulder pain could be due to stimulation of (a) the supraclavicular nerves of the cervical plexus (C3–C4), which innervate the skin over the shoulder, or (b) C5 articular nerves to the shoulder joint, such as the axillary or suprascapular nerves (21).
In order to reduce mild to moderate shoulder pain, it is recommended that gelatin sponge particles be soaked with a small amount (1–2 mL) of 1% lidocaine. In the event of severe shoulder pain during the procedure, lidocaine can be injected intraarterially in order to relieve the pain immediately (1).
TACE through the IPA frequently results in lung CT changes including iodized oil accumulation in the lung field, consolidation, pleural effusion, and atelectasis (1–3,22). Most patients with pulmonary complications are asymptomatic, but symptomatic pulmonary embolism and hydro-pneumothorax secondary to pulmonary infarction occur in some cases, likely because of the large volume of chemotherapeutic agents used passing through an IPA–pulmonary vasculature shunt (23). Angiographic abnormalities such as arteriovenous shunts, dilated anastomotic branches, and dense pleural staining are important risk factors for pulmonary complications of TACE through the IPA (22).
In patients with parasitic supply from the IPA in whom pleural and pulmonary staining are detected on IPA angiograms, pulmonary complications of IPA embolization may be reduced if these areas of staining can be completely embolized before the injection of iodine oil and chemotherapeutic agents. This can be accomplished with the use of large gelatin sponge particles inserted through a 3-F microcatheter with its tip located just proximal to the stained region.
In TACE through the IPA, chemoembolization agents can also be directed into accessory gastric branches or gastroesophageal branches. If these branches are not recognized before the IPA embolization and appropriate protective measures are not taken, gastroesophageal complications—such as gastritis, esophagitis, or ulcer—are unavoidable. Preventive measures that can be taken are superselective chemoembolization of tumor-feeding vessels and embolization of the accessory gastric branches with microcoils and/or n-butyl cyanoacrylate (24,25).
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Conclusions
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The IPA is the most frequently encountered of the extrahepatic collateral arteries that supply HCCs. Regardless of the patency of the hepatic artery, angiographic study of the IPA may be routinely recommended when HCCs are located in the bare area of the liver. Moreover, other pathologic conditions related to the IPA should be borne in mind. Because variation frequently exists in the origin of the IPA, it may at times be difficult for the angiographer to thoroughly study the IPA. However, careful analysis of arterial phase CT scans may be significantly helpful in evaluating the IPA. Careful interpretation of the angiographic findings of the IPA is also important, as a thorough knowledge of the vascular anatomy and variations of the IPA is critical to effective interventional treatment of the pathologic conditions related to the IPA.
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Footnotes
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Abbreviations: CTAP = CT during arterial portography, CTHA = CT during hepatic arteriography, HCC = hepatocellular carcinoma, IPA = inferior phrenic artery, TACE = transcatheter arterial chemoembolization
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References
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Abstract
Introduction
