- Email: [email protected]
Balloon-Assisted Flow Diversion and Selective Catheterization of Target Vessels for Hepatic Transarterial Embolization
Volume 27
’
Number 2
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February
’
2016
possible that these residents were more likely to complete the survey, introducing response bias, which may have been related to the subject of the email distributed or the title of the electronic survey. Also, a number of residents did not answer all the survey questions, which could contribute to inaccurate results. Another limitation of the study is that the survey respondents were asked to recall their thoughts and intentions from when they were medical students several years earlier. It is certainly possible that the recollections of the senior radiology residents are not entirely accurate. Currently, most medical students are not prepared to make the fellowship and career decision between DR and IR. Most have entered radiology residency considering IR and DR subspecialties and needed resident IR rotations to decide for or against IR as a subspecialty. Most medical students will soon have to decide between IR and DR specialization before participating in IR rotations, which risks applicants making uninformed choices. It is therefore important that medical students are exposed to IR as a career encompassing DR, imageguided procedures, and patient care. Medical school mentors, as well as IR and DR physicians, must improve efforts to educate medical students and create opportunities for extensive exposure to these newly distinct specialties and training programs. DR and IR residency programs should anticipate requests for transfers between these programs within the same institution.
REFERENCES 1. Kaufman JA. The interventional radiology/diagnostic radiology certificate and interventional radiology residency. Radiology 2014; 273:318–321. 2. Heitkamp DE, Gunderman RB. The interventional radiology/diagnostic radiology certificate: asking the hard questions. Radiology 2014; 273:322–325. 3. National Resident Matching Program. Results and Data: Specialties Matching Service 2014 Appointment Year. Washington, DC: National Resident Matching Program; 2014, Available at: http://www.nrmp.org/ wp-content/uploads/2013/08/National-Resident-Matching-Program-NRM P-Results-and-Data-SMS-2014-Final.pdf. Accessed October 2, 2015. 4. National Resident Matching Program. Charting Outcomes in the Match: Characteristics of Applicants Who Matched to Their Preferred Specialty in the 2009 Main Residency Match. Washington, DC: National Resident Matching Program; 2009, Available at: https://www.med.wayne.edu/ aesculapians/documents/Year%20Four/2009%20Match.pdf. Accessed October 2, 2015.
283
Bruno C. Odisio, MD Department of Interventional Radiology The University of Texas M.D. Anderson Cancer Center 1515 Holcombe Blvd Unit 1471 Houston, TX 77030-4009
Editor: Selective transarterial embolization for liver neoplasms is performed with the aim to improve treatment efficacy and minimize adverse events. Selective catheterization of the hepatic arteries supplying the target tumor is sometimes challenging or even impossible. Temporary balloon occlusion techniques have been used successfully to redirect the flow of blood and embolic material during transarterial procedures (1–4). We describe a balloon occlusion technique applied to facilitate selective catheterization of the small left and middle hepatic arteries during bland embolization in a patient with a gastrointestinal stromal tumor hepatic metastasis. This case report was compliant with the Health Insurance Portability and Accountability Act and approved by the institutional review board with a waiver of informed consent. A 42-year-old woman with recurrent metastatic gastrointestinal stromal tumor to the liver, status post partial gastrectomy and partial hepatectomy, underwent three sessions of bland embolization over a 9-month period with partial response and subsequent tumor progression. Because of the proximity of the lesion to the stomach and colon and history of hepatic resection, percutaneous ablation was not considered to be a safe option, and repeat embolization was recommended. Via a femoral arterial approach, a 5-F SOS Omni 2 catheter (AngioDynamics, Latham, New York) was used to select the celiac artery (Fig 1). A 2.8-F microcatheter
Balloon-Assisted Flow Diversion and Selective Catheterization of Target Vessels for Hepatic Transarterial Embolization From: Mohamed E. Abdelsalam, MD Armeen Mahvash, MD Rony Avritscher, MD Stephen E. McRae, MD
None of the authors have identified a conflict of interest. http://dx.doi.org/10.1016/j.jvir.2015.10.022
Figure 1. Celiac axis digital subtraction angiography using a 5-F SOS Omni 2. Dotted circle indicates a hypervascular area representing the residual tumor.
284
’
Letters to the Editor
(PROGREAT; Terumo Medical Corporation, Somerset, New Jersey) and 0.021-inch guide wire (Terumo Medical Corporation) were used to select the common hepatic artery. Common hepatic artery angiography and cone-beam computed tomography (CT) angiography revealed small left and middle hepatic arteries supplying the persistent residual tumor. After several unsuccessful attempts to catheterize the left and middle hepatic arteries with 2.8-F and 1.9-F microcatheters (PROWLER; Codman & Shurtleff, Inc, Raynham, Massachusetts) and a 0.014-inch guide wire (Transend; Boston Scientific, Marlborough, Massachusetts), the 5-F femoral sheath was exchanged for an 8-F guiding sheath (Flexor Ansel; Cook, Inc, Bloomington, Indiana) to select the celiac artery. A 3-F balloon catheter (Fogarty; Edwards Lifesciences, Irvine, California) was advanced over an 0.018-inch guide wire (Transend) into the proximal right hepatic artery distal to the left and middle hepatic artery origins (Fig 2a). Contrast agent (0.15 mL) was used to inflate the balloon after intravenous administration of heparin (2,000 IU). Subsequently, the 1.9-F microcatheter and 0.014-inch guide wire were advanced in parallel to the balloon catheter and were used for easy selection on the first attempt of the left and middle hepatic arteries, respectively (Fig 2b, c). Once each vessel was selected, the occlusion balloon catheter was deflated to reduce the possibility of arterial thrombosis and nontarget embolization via cross-filling branches originating from the middle and left hepatic arteries. Bland embolization was performed with 40-mm particles until near-stasis was achieved. Noncontrast cone-beam CT performed at the end of the procedure showed deposition of contrast agent at the target lesion (Fig 3). The procedure was completed uneventfully. The successful use of balloon occlusion techniques during transarterial hepatic chemoembolization has been described elsewhere (1–3). Todoroki et al (2) described the use of a new double-lumen microballoon catheter
Abdelsalam et al
’
JVIR
with a side hole. After occluding the parent artery distally, the end hole of the catheter was occluded by a specific wire, and the chemoembolic agent was delivered through the side hole into the target artery, which was initially difficult to select with a microcatheter. We used a balloon occlusion technique not only to alter temporarily the intrahepatic arterial hemodynamics but also, owing to the diminutive size and acute angulation of the feeding vessels, to facilitate selective catheterization of two challenging vessels. We hypothesize that temporarily occluding the right hepatic artery redirected blood flow into the small left and middle hepatic arteries, facilitating their catheterization. In addition, introducing the occlusion balloon may have straightened the hepatic artery and
Figure 3. Non–contrast-enhanced cone-beam CT image showing a hyperdense area of contrast and embolic material deposition within the target lesion (arrows).
Figure 2. (a) Digital subtraction angiography through the Ansel sheath (arrow) in the celiac axis after balloon catheter placement and inflation at the right hepatic artery (arrowhead). Note some spasm of the common and proper hepatic arteries. (b) Selective digital subtraction angiography of the left hepatic artery using a 1.9-F microcatheter (arrow) after balloon inflation at the right hepatic artery (arrowhead). (c) Selective digital subtraction angiography of the middle hepatic artery using a 1.9-F microcatheter (arrow) after balloon inflation at the right hepatic artery (arrowhead). Note tumor enhancement (asterisk).
Volume 27
’
Number 2
’
February
’
2016
eliminated the vessel tortuosity, which may have also facilitated the selection of the target vessels. Differences in the caliber and pressures of the selected arteries were not measured because of their diminutive calibers. The following should be considered while choosing the balloon-assisted flow diversion technique for catheterization. Currently available peripheral balloon catheters are relatively inflexible, increasing risk of vascular spasm or dissection, particularly in patients with tortuous vessels and patients receiving antiangiogenesis therapy. Also, stasis associated with balloon inflation could cause thrombosis in the parent vessel. Intravenous heparin administration and reduction of the balloon inflation time reduce the risk of thrombosis. Finally, the balloon cost may be balanced by the cost of using additional catheters and wires. In conclusion, temporary distal balloon occlusion might be a useful alternative technique for the catheterization and subsequent embolization of small, challenging vessels, making it a potentially valuable tool in cases of challenging selective catheterization.
REFERENCES 1. Nakamura H, Tanaka M, Oi H. Hepatic embolization from the common hepatic artery using balloon occlusion technique. AJR Am J Roentgenol 1985; 145:115–116. 2. Todoroki W, Hirakawa M, Nagao E, Soeda H, Tsuruta S, Honda H. Transarterial chemoembolization for hepatocellular carcinoma using a new double-lumen microballoon catheter with a side hole. J Vasc Interv Radiol 2014; 25:1485–1486. 3. Matsumoto T, Endo J, Hashida K, et al. Balloon-occluded transarterial chemoembolization using a 1.8-French tip coaxial microballoon catheter for hepatocellular carcinoma: technical and safety considerations. Minim Invasive Ther Allied Technol 2015; 24:94–100. 4. Pierot L, Cognard C, Spelle L, Moret J. Safety and efficacy of balloon remodeling technique during endovascular treatment of intracranial aneurysms: critical review of the literature. AJNR Am J Neuroradiol 2012; 33: 12–15.
Blood Flow Redistribution Using the AMPLATZER Vascular Plug 4 before Distal Pancreatectomy with en-Bloc Celiac Axis Resection From: Masaki Ishikawa, MD, PhD Kenji Kajiwara, MD Wataru Fukumoto, MD Yoshiaki Murakami, MD, PhD Kazuo Awai, MD, PhD Department of Diagnostic Radiology, Hiroshima University Hospital (M.I.); Department of Diagnostic Radiology, Graduate School of Biomedical and Health Sciences (K.K., W.F.);
K.A. is a paid medical advisor for Eizai (Tokyo, Japan) and Daiichi Sankyo (Tokyo, Japan) and received grants from Toshiba Medical Systems (Otawara, Japan), Bayer Yakuhin (Osaka, Japan), Eizai, and Daiichi Sankyo. None of the other authors have identified a conflict of interest. http://dx.doi.org/10.1016/j.jvir.2015.09.012
285
Department of Surgery, Applied Life Sciences Institute of Biomedical & Health Sciences (Y.M.); and Department of Diagnostic Radiology, Institute and Graduate School of Biomedical and Health Sciences (K.A.) Hiroshima University 1-2-3, Kasumi, Minami-ku Hiroshima, Hiroshima 734-8551, Japan
Editor: Locally advanced cancer of the pancreatic body often involves the common hepatic artery (CHA) and/or celiac axis with perineural invasion into the surrounding nerve plexus, which predicts a poor prognosis after distal pancreatectomy (DP) if performed alone. DP with en bloc celiac axis resection (CAR) improves the survival rate and the quality of postoperative life, but morbidity rates associated with ischemic complications are high. In published reports, after DP with CAR (DP-CAR), one of six patients experienced hepatic ischemia requiring artery reconstruction after CHA clamping (1), and three of nine patients manifested ischemic gastropathy (2). However, preoperative embolization of the CHA for DP with CAR lowered the incidence of complications after DP-CAR (3). We present a patient without ischemic complications after DP-CAR and preoperative embolization with an AMPLATZER Vascular Plug (AVP) 4 (St. Jude Medical, St. Paul, Minnesota). Our institutional review board did not require approval for this retrospective case report. Chest radiography during a periodic medical check-up detected a lesion in a 79-year-old man. Computed tomography (CT) revealed a tumor on the pancreatic body but no chest lesions. Positron emission tomography/CT showed high intensity in the area of the pancreatic body (maximum standardized uptake value, 12.8) but no other high-intensity lesions, and he was referred to our institution. Brush cytology during endoscopic retrograde cholangiopancreatography disclosed invasive ductal carcinoma. The diagnosis was locally advanced pancreatic cancer without metastasis. He underwent three courses of chemotherapy before embolization of the CHA and subsequent DP-CAR. Celiac and three-dimensional angiograms were acquired via the right femoral artery with a 4-F catheter (Excellent EN catheter; Hanaco Medical, Saitama, Japan) and a 4-F sheath. Celiac arteriography revealed encasement of the proximal portion of the splenic artery by the tumor (Fig a). The catheter was advanced over a guide wire (Radifocus; Terumo, Tokyo, Japan) into the gastroduodenal artery. The detector was adjusted to facilitate observation of as long a stretch of the CHA as possible with reference to three-dimensional images. An 8-mm-diameter AVP 4 was advanced to the tip of the catheter; the catheter was retracted to the target position of the AVP 4, which was then expanded without releasing it. An angiogram obtained via a 3.5-F catheter (Excellent EN catheter) through another 3.5-F sheath
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Number 2
’
February
’
2016
possible that these residents were more likely to complete the survey, introducing response bias, which may have been related to the subject of the email distributed or the title of the electronic survey. Also, a number of residents did not answer all the survey questions, which could contribute to inaccurate results. Another limitation of the study is that the survey respondents were asked to recall their thoughts and intentions from when they were medical students several years earlier. It is certainly possible that the recollections of the senior radiology residents are not entirely accurate. Currently, most medical students are not prepared to make the fellowship and career decision between DR and IR. Most have entered radiology residency considering IR and DR subspecialties and needed resident IR rotations to decide for or against IR as a subspecialty. Most medical students will soon have to decide between IR and DR specialization before participating in IR rotations, which risks applicants making uninformed choices. It is therefore important that medical students are exposed to IR as a career encompassing DR, imageguided procedures, and patient care. Medical school mentors, as well as IR and DR physicians, must improve efforts to educate medical students and create opportunities for extensive exposure to these newly distinct specialties and training programs. DR and IR residency programs should anticipate requests for transfers between these programs within the same institution.
REFERENCES 1. Kaufman JA. The interventional radiology/diagnostic radiology certificate and interventional radiology residency. Radiology 2014; 273:318–321. 2. Heitkamp DE, Gunderman RB. The interventional radiology/diagnostic radiology certificate: asking the hard questions. Radiology 2014; 273:322–325. 3. National Resident Matching Program. Results and Data: Specialties Matching Service 2014 Appointment Year. Washington, DC: National Resident Matching Program; 2014, Available at: http://www.nrmp.org/ wp-content/uploads/2013/08/National-Resident-Matching-Program-NRM P-Results-and-Data-SMS-2014-Final.pdf. Accessed October 2, 2015. 4. National Resident Matching Program. Charting Outcomes in the Match: Characteristics of Applicants Who Matched to Their Preferred Specialty in the 2009 Main Residency Match. Washington, DC: National Resident Matching Program; 2009, Available at: https://www.med.wayne.edu/ aesculapians/documents/Year%20Four/2009%20Match.pdf. Accessed October 2, 2015.
283
Bruno C. Odisio, MD Department of Interventional Radiology The University of Texas M.D. Anderson Cancer Center 1515 Holcombe Blvd Unit 1471 Houston, TX 77030-4009
Editor: Selective transarterial embolization for liver neoplasms is performed with the aim to improve treatment efficacy and minimize adverse events. Selective catheterization of the hepatic arteries supplying the target tumor is sometimes challenging or even impossible. Temporary balloon occlusion techniques have been used successfully to redirect the flow of blood and embolic material during transarterial procedures (1–4). We describe a balloon occlusion technique applied to facilitate selective catheterization of the small left and middle hepatic arteries during bland embolization in a patient with a gastrointestinal stromal tumor hepatic metastasis. This case report was compliant with the Health Insurance Portability and Accountability Act and approved by the institutional review board with a waiver of informed consent. A 42-year-old woman with recurrent metastatic gastrointestinal stromal tumor to the liver, status post partial gastrectomy and partial hepatectomy, underwent three sessions of bland embolization over a 9-month period with partial response and subsequent tumor progression. Because of the proximity of the lesion to the stomach and colon and history of hepatic resection, percutaneous ablation was not considered to be a safe option, and repeat embolization was recommended. Via a femoral arterial approach, a 5-F SOS Omni 2 catheter (AngioDynamics, Latham, New York) was used to select the celiac artery (Fig 1). A 2.8-F microcatheter
Balloon-Assisted Flow Diversion and Selective Catheterization of Target Vessels for Hepatic Transarterial Embolization From: Mohamed E. Abdelsalam, MD Armeen Mahvash, MD Rony Avritscher, MD Stephen E. McRae, MD
None of the authors have identified a conflict of interest. http://dx.doi.org/10.1016/j.jvir.2015.10.022
Figure 1. Celiac axis digital subtraction angiography using a 5-F SOS Omni 2. Dotted circle indicates a hypervascular area representing the residual tumor.
284
’
Letters to the Editor
(PROGREAT; Terumo Medical Corporation, Somerset, New Jersey) and 0.021-inch guide wire (Terumo Medical Corporation) were used to select the common hepatic artery. Common hepatic artery angiography and cone-beam computed tomography (CT) angiography revealed small left and middle hepatic arteries supplying the persistent residual tumor. After several unsuccessful attempts to catheterize the left and middle hepatic arteries with 2.8-F and 1.9-F microcatheters (PROWLER; Codman & Shurtleff, Inc, Raynham, Massachusetts) and a 0.014-inch guide wire (Transend; Boston Scientific, Marlborough, Massachusetts), the 5-F femoral sheath was exchanged for an 8-F guiding sheath (Flexor Ansel; Cook, Inc, Bloomington, Indiana) to select the celiac artery. A 3-F balloon catheter (Fogarty; Edwards Lifesciences, Irvine, California) was advanced over an 0.018-inch guide wire (Transend) into the proximal right hepatic artery distal to the left and middle hepatic artery origins (Fig 2a). Contrast agent (0.15 mL) was used to inflate the balloon after intravenous administration of heparin (2,000 IU). Subsequently, the 1.9-F microcatheter and 0.014-inch guide wire were advanced in parallel to the balloon catheter and were used for easy selection on the first attempt of the left and middle hepatic arteries, respectively (Fig 2b, c). Once each vessel was selected, the occlusion balloon catheter was deflated to reduce the possibility of arterial thrombosis and nontarget embolization via cross-filling branches originating from the middle and left hepatic arteries. Bland embolization was performed with 40-mm particles until near-stasis was achieved. Noncontrast cone-beam CT performed at the end of the procedure showed deposition of contrast agent at the target lesion (Fig 3). The procedure was completed uneventfully. The successful use of balloon occlusion techniques during transarterial hepatic chemoembolization has been described elsewhere (1–3). Todoroki et al (2) described the use of a new double-lumen microballoon catheter
Abdelsalam et al
’
JVIR
with a side hole. After occluding the parent artery distally, the end hole of the catheter was occluded by a specific wire, and the chemoembolic agent was delivered through the side hole into the target artery, which was initially difficult to select with a microcatheter. We used a balloon occlusion technique not only to alter temporarily the intrahepatic arterial hemodynamics but also, owing to the diminutive size and acute angulation of the feeding vessels, to facilitate selective catheterization of two challenging vessels. We hypothesize that temporarily occluding the right hepatic artery redirected blood flow into the small left and middle hepatic arteries, facilitating their catheterization. In addition, introducing the occlusion balloon may have straightened the hepatic artery and
Figure 3. Non–contrast-enhanced cone-beam CT image showing a hyperdense area of contrast and embolic material deposition within the target lesion (arrows).
Figure 2. (a) Digital subtraction angiography through the Ansel sheath (arrow) in the celiac axis after balloon catheter placement and inflation at the right hepatic artery (arrowhead). Note some spasm of the common and proper hepatic arteries. (b) Selective digital subtraction angiography of the left hepatic artery using a 1.9-F microcatheter (arrow) after balloon inflation at the right hepatic artery (arrowhead). (c) Selective digital subtraction angiography of the middle hepatic artery using a 1.9-F microcatheter (arrow) after balloon inflation at the right hepatic artery (arrowhead). Note tumor enhancement (asterisk).
Volume 27
’
Number 2
’
February
’
2016
eliminated the vessel tortuosity, which may have also facilitated the selection of the target vessels. Differences in the caliber and pressures of the selected arteries were not measured because of their diminutive calibers. The following should be considered while choosing the balloon-assisted flow diversion technique for catheterization. Currently available peripheral balloon catheters are relatively inflexible, increasing risk of vascular spasm or dissection, particularly in patients with tortuous vessels and patients receiving antiangiogenesis therapy. Also, stasis associated with balloon inflation could cause thrombosis in the parent vessel. Intravenous heparin administration and reduction of the balloon inflation time reduce the risk of thrombosis. Finally, the balloon cost may be balanced by the cost of using additional catheters and wires. In conclusion, temporary distal balloon occlusion might be a useful alternative technique for the catheterization and subsequent embolization of small, challenging vessels, making it a potentially valuable tool in cases of challenging selective catheterization.
REFERENCES 1. Nakamura H, Tanaka M, Oi H. Hepatic embolization from the common hepatic artery using balloon occlusion technique. AJR Am J Roentgenol 1985; 145:115–116. 2. Todoroki W, Hirakawa M, Nagao E, Soeda H, Tsuruta S, Honda H. Transarterial chemoembolization for hepatocellular carcinoma using a new double-lumen microballoon catheter with a side hole. J Vasc Interv Radiol 2014; 25:1485–1486. 3. Matsumoto T, Endo J, Hashida K, et al. Balloon-occluded transarterial chemoembolization using a 1.8-French tip coaxial microballoon catheter for hepatocellular carcinoma: technical and safety considerations. Minim Invasive Ther Allied Technol 2015; 24:94–100. 4. Pierot L, Cognard C, Spelle L, Moret J. Safety and efficacy of balloon remodeling technique during endovascular treatment of intracranial aneurysms: critical review of the literature. AJNR Am J Neuroradiol 2012; 33: 12–15.
Blood Flow Redistribution Using the AMPLATZER Vascular Plug 4 before Distal Pancreatectomy with en-Bloc Celiac Axis Resection From: Masaki Ishikawa, MD, PhD Kenji Kajiwara, MD Wataru Fukumoto, MD Yoshiaki Murakami, MD, PhD Kazuo Awai, MD, PhD Department of Diagnostic Radiology, Hiroshima University Hospital (M.I.); Department of Diagnostic Radiology, Graduate School of Biomedical and Health Sciences (K.K., W.F.);
K.A. is a paid medical advisor for Eizai (Tokyo, Japan) and Daiichi Sankyo (Tokyo, Japan) and received grants from Toshiba Medical Systems (Otawara, Japan), Bayer Yakuhin (Osaka, Japan), Eizai, and Daiichi Sankyo. None of the other authors have identified a conflict of interest. http://dx.doi.org/10.1016/j.jvir.2015.09.012
285
Department of Surgery, Applied Life Sciences Institute of Biomedical & Health Sciences (Y.M.); and Department of Diagnostic Radiology, Institute and Graduate School of Biomedical and Health Sciences (K.A.) Hiroshima University 1-2-3, Kasumi, Minami-ku Hiroshima, Hiroshima 734-8551, Japan
Editor: Locally advanced cancer of the pancreatic body often involves the common hepatic artery (CHA) and/or celiac axis with perineural invasion into the surrounding nerve plexus, which predicts a poor prognosis after distal pancreatectomy (DP) if performed alone. DP with en bloc celiac axis resection (CAR) improves the survival rate and the quality of postoperative life, but morbidity rates associated with ischemic complications are high. In published reports, after DP with CAR (DP-CAR), one of six patients experienced hepatic ischemia requiring artery reconstruction after CHA clamping (1), and three of nine patients manifested ischemic gastropathy (2). However, preoperative embolization of the CHA for DP with CAR lowered the incidence of complications after DP-CAR (3). We present a patient without ischemic complications after DP-CAR and preoperative embolization with an AMPLATZER Vascular Plug (AVP) 4 (St. Jude Medical, St. Paul, Minnesota). Our institutional review board did not require approval for this retrospective case report. Chest radiography during a periodic medical check-up detected a lesion in a 79-year-old man. Computed tomography (CT) revealed a tumor on the pancreatic body but no chest lesions. Positron emission tomography/CT showed high intensity in the area of the pancreatic body (maximum standardized uptake value, 12.8) but no other high-intensity lesions, and he was referred to our institution. Brush cytology during endoscopic retrograde cholangiopancreatography disclosed invasive ductal carcinoma. The diagnosis was locally advanced pancreatic cancer without metastasis. He underwent three courses of chemotherapy before embolization of the CHA and subsequent DP-CAR. Celiac and three-dimensional angiograms were acquired via the right femoral artery with a 4-F catheter (Excellent EN catheter; Hanaco Medical, Saitama, Japan) and a 4-F sheath. Celiac arteriography revealed encasement of the proximal portion of the splenic artery by the tumor (Fig a). The catheter was advanced over a guide wire (Radifocus; Terumo, Tokyo, Japan) into the gastroduodenal artery. The detector was adjusted to facilitate observation of as long a stretch of the CHA as possible with reference to three-dimensional images. An 8-mm-diameter AVP 4 was advanced to the tip of the catheter; the catheter was retracted to the target position of the AVP 4, which was then expanded without releasing it. An angiogram obtained via a 3.5-F catheter (Excellent EN catheter) through another 3.5-F sheath