Minimally Invasive Treatment of Malignant Hepatic Tumors: At the Threshold of a Major Breakthrough1
Gerald D. Dodd, III, MD,
Michael C. Soulen, MD ,
Robert A. Kane, MD ,
Tito Livraghi, MD ,
William R. Lees, MB BS, FRCR ,
Yasuyuki Yamashita, MD ,
Alison R. Gillams, MBChB, MRCP, FRCR ,
Okkes I. Karahan, MD and
Hyunchul Rhim, MD, PhD
1 From the Departments of Radiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr, San Antonio, TX 78284-7800 (G.D.D., O.I.K., H.R.); University of Pennsylvania, Philadelphia (M.C.S); Beth Israel Deaconess Medical Center, Boston, Mass (R.A.K.); Ospedale Civile, Vimercate, Milan, Italy (T.L.); University College London, Middlesex Hospital, London, England (W.R.L., A.R.G.); Kumamoto University, Kumamoto, Japan (Y.Y); Erciyes University, Kayseri, Turkey (O.I.K); and Hanyang University, Seoul, South Korea (H.R). Recipient of a Summa Cum Laude award and an Excellence in Design award at the 1998 RSNA scientific assembly. Received May 17, 1999; revisions requested July 22 and received August 24; accepted August 25. Address reprint requests to G.D.D.
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Figure 1. Computer-generated image depicts the essential elements of US-guided percutaneous ablation of liver tumors as well as representative pre- and postablation CT scans.
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Figure 2a. Mechanism of radio-frequency ablation. (a) Schematic depicts a four-prong needle electrode in which an alternating electric current at 460 KHz has caused ionic agitation around the electrode tip. (b) Schematic illustrates the ionic agitation, which causes frictional heat immediately around the needle. (c) Schematic shows how the heat caused by the agitation expands by conduction into the surrounding tissues to form a roughly spherical thermal injury.
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Figure 2b. Mechanism of radio-frequency ablation. (a) Schematic depicts a four-prong needle electrode in which an alternating electric current at 460 KHz has caused ionic agitation around the electrode tip. (b) Schematic illustrates the ionic agitation, which causes frictional heat immediately around the needle. (c) Schematic shows how the heat caused by the agitation expands by conduction into the surrounding tissues to form a roughly spherical thermal injury.
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Figure 2c. Mechanism of radio-frequency ablation. (a) Schematic depicts a four-prong needle electrode in which an alternating electric current at 460 KHz has caused ionic agitation around the electrode tip. (b) Schematic illustrates the ionic agitation, which causes frictional heat immediately around the needle. (c) Schematic shows how the heat caused by the agitation expands by conduction into the surrounding tissues to form a roughly spherical thermal injury.
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Figure 3a. Photographs show radio-frequency ablation needle electrodes in use today, including a 15-gauge needle electrode with four retractable prongs (Rita Medical Systems) (a), a 14-gauge needle electrode with 10 retractable prongs (Radiotherapeutics) (b), and a 17-gauge internally cooled-tip needle in a three-needle cluster (Radionics) (c).
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Figure 3b. Photographs show radio-frequency ablation needle electrodes in use today, including a 15-gauge needle electrode with four retractable prongs (Rita Medical Systems) (a), a 14-gauge needle electrode with 10 retractable prongs (Radiotherapeutics) (b), and a 17-gauge internally cooled-tip needle in a three-needle cluster (Radionics) (c).
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Figure 3c. Photographs show radio-frequency ablation needle electrodes in use today, including a 15-gauge needle electrode with four retractable prongs (Rita Medical Systems) (a), a 14-gauge needle electrode with 10 retractable prongs (Radiotherapeutics) (b), and a 17-gauge internally cooled-tip needle in a three-needle cluster (Radionics) (c).
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Figure 4a. Radio-frequency ablation treatment strategies. On the basis of a 3-cm-diameter spherical thermal injury created by a single ablation, the following three ablation strategies can be used to treat most tumors. (a) Schematic illustrates how tumors less than 2 cm can easily be treated with one ablation. The active elements of the ablation needle are centered across the tumor. (b) Schematic shows how tumors 2-3 cm in diameter are treated by six overlapping ablations. Four ablations are performed in the x-y plane, and two are performed along the z axis. All ablations are positioned to touch the center of the tumor. If placed correctly, the ablations create an inner spherical injury that measures 3.7 cm in diameter. (c) Schematic depicts systematically overlapped "thermal cylinders," which are a more effective way to ablate large tumors, rather than creating random overlapping ablations (such as seen in b). Each cylinder is created by overlapping individual ablations along a single needle tract from the deepest to the most superficial portions of a tumor. Each ablation and thermal cylinder is overlapped by 50%.
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Figure 4b. Radio-frequency ablation treatment strategies. On the basis of a 3-cm-diameter spherical thermal injury created by a single ablation, the following three ablation strategies can be used to treat most tumors. (a) Schematic illustrates how tumors less than 2 cm can easily be treated with one ablation. The active elements of the ablation needle are centered across the tumor. (b) Schematic shows how tumors 2-3 cm in diameter are treated by six overlapping ablations. Four ablations are performed in the x-y plane, and two are performed along the z axis. All ablations are positioned to touch the center of the tumor. If placed correctly, the ablations create an inner spherical injury that measures 3.7 cm in diameter. (c) Schematic depicts systematically overlapped "thermal cylinders," which are a more effective way to ablate large tumors, rather than creating random overlapping ablations (such as seen in b). Each cylinder is created by overlapping individual ablations along a single needle tract from the deepest to the most superficial portions of a tumor. Each ablation and thermal cylinder is overlapped by 50%.
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Figure 4c. Radio-frequency ablation treatment strategies. On the basis of a 3-cm-diameter spherical thermal injury created by a single ablation, the following three ablation strategies can be used to treat most tumors. (a) Schematic illustrates how tumors less than 2 cm can easily be treated with one ablation. The active elements of the ablation needle are centered across the tumor. (b) Schematic shows how tumors 2-3 cm in diameter are treated by six overlapping ablations. Four ablations are performed in the x-y plane, and two are performed along the z axis. All ablations are positioned to touch the center of the tumor. If placed correctly, the ablations create an inner spherical injury that measures 3.7 cm in diameter. (c) Schematic depicts systematically overlapped "thermal cylinders," which are a more effective way to ablate large tumors, rather than creating random overlapping ablations (such as seen in b). Each cylinder is created by overlapping individual ablations along a single needle tract from the deepest to the most superficial portions of a tumor. Each ablation and thermal cylinder is overlapped by 50%.
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Figure 5a. CT evaluation of radio-frequency thermal ablation. (a) CT scan obtained before ablation shows a hypervascular hepatocellular carcinoma (arrow). (b) CT scan obtained after ablation shows that the tumor has become avascular. Note the prominent peritumoral hyperemia around the treated tumor (arrowheads) that is caused by the ablation process.
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Figure 5b. CT evaluation of radio-frequency thermal ablation. (a) CT scan obtained before ablation shows a hypervascular hepatocellular carcinoma (arrow). (b) CT scan obtained after ablation shows that the tumor has become avascular. Note the prominent peritumoral hyperemia around the treated tumor (arrowheads) that is caused by the ablation process.
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Figure 6. Microwave ablation physics. Drawing shows how microwaves heat biologic tissue by causing rotation of water molecules.
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Figure 7. Photograph shows microwave ablation equipment, including a 150-W, 2,450-MHz microwave generator (Microtaze; Heiwa, Osaka, Japan) (left) and needle electrodes (right).
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Figure 8. Microwave ablation of swine liver. Photograph of the cut surface of the liver shows an elliptical ablation (yellow arrowheads) around the distal shaft (arrow) of the monopolar electrode. Note the tip of the electrode (asterisk).
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Figure 9a. CT evaluation of microwave ablation performed in a 68-year-old man with hepatocellular carcinoma who had previously been treated with arterial chemoembolization with iodized oil. (a) Enhanced CT scan obtained before embolization shows a hypervascular tumor nodule (arrowheads). (b) Unenhanced CT scan obtained 7 days after embolization shows incomplete accumulation of iodized oil in the tumor (arrow). (c) Sonogram obtained before microwave ablation (left) shows a 35-mm hypoechoic nodule in the anterior segment of the right hepatic lobe (arrows). Sonogram obtained immediately after treatment (two emissions) (right) shows a markedly echogenic region of coagulation (arrow) that has replaced the tumor. (d) Enhanced CT scan obtained 4 days after microwave ablation shows ablated tissue as unenhanced areas within and around the tumor (arrows). (e) Dynamic CT scan obtained 9 months after treatment shows that the lesion (arrow) has decreased in size, without evidence of new tumor growth.
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Figure 9b. CT evaluation of microwave ablation performed in a 68-year-old man with hepatocellular carcinoma who had previously been treated with arterial chemoembolization with iodized oil. (a) Enhanced CT scan obtained before embolization shows a hypervascular tumor nodule (arrowheads). (b) Unenhanced CT scan obtained 7 days after embolization shows incomplete accumulation of iodized oil in the tumor (arrow). (c) Sonogram obtained before microwave ablation (left) shows a 35-mm hypoechoic nodule in the anterior segment of the right hepatic lobe (arrows). Sonogram obtained immediately after treatment (two emissions) (right) shows a markedly echogenic region of coagulation (arrow) that has replaced the tumor. (d) Enhanced CT scan obtained 4 days after microwave ablation shows ablated tissue as unenhanced areas within and around the tumor (arrows). (e) Dynamic CT scan obtained 9 months after treatment shows that the lesion (arrow) has decreased in size, without evidence of new tumor growth.
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Figure 9c. CT evaluation of microwave ablation performed in a 68-year-old man with hepatocellular carcinoma who had previously been treated with arterial chemoembolization with iodized oil. (a) Enhanced CT scan obtained before embolization shows a hypervascular tumor nodule (arrowheads). (b) Unenhanced CT scan obtained 7 days after embolization shows incomplete accumulation of iodized oil in the tumor (arrow). (c) Sonogram obtained before microwave ablation (left) shows a 35-mm hypoechoic nodule in the anterior segment of the right hepatic lobe (arrows). Sonogram obtained immediately after treatment (two emissions) (right) shows a markedly echogenic region of coagulation (arrow) that has replaced the tumor. (d) Enhanced CT scan obtained 4 days after microwave ablation shows ablated tissue as unenhanced areas within and around the tumor (arrows). (e) Dynamic CT scan obtained 9 months after treatment shows that the lesion (arrow) has decreased in size, without evidence of new tumor growth.
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Figure 9d. CT evaluation of microwave ablation performed in a 68-year-old man with hepatocellular carcinoma who had previously been treated with arterial chemoembolization with iodized oil. (a) Enhanced CT scan obtained before embolization shows a hypervascular tumor nodule (arrowheads). (b) Unenhanced CT scan obtained 7 days after embolization shows incomplete accumulation of iodized oil in the tumor (arrow). (c) Sonogram obtained before microwave ablation (left) shows a 35-mm hypoechoic nodule in the anterior segment of the right hepatic lobe (arrows). Sonogram obtained immediately after treatment (two emissions) (right) shows a markedly echogenic region of coagulation (arrow) that has replaced the tumor. (d) Enhanced CT scan obtained 4 days after microwave ablation shows ablated tissue as unenhanced areas within and around the tumor (arrows). (e) Dynamic CT scan obtained 9 months after treatment shows that the lesion (arrow) has decreased in size, without evidence of new tumor growth.
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Figure 9e. CT evaluation of microwave ablation performed in a 68-year-old man with hepatocellular carcinoma who had previously been treated with arterial chemoembolization with iodized oil. (a) Enhanced CT scan obtained before embolization shows a hypervascular tumor nodule (arrowheads). (b) Unenhanced CT scan obtained 7 days after embolization shows incomplete accumulation of iodized oil in the tumor (arrow). (c) Sonogram obtained before microwave ablation (left) shows a 35-mm hypoechoic nodule in the anterior segment of the right hepatic lobe (arrows). Sonogram obtained immediately after treatment (two emissions) (right) shows a markedly echogenic region of coagulation (arrow) that has replaced the tumor. (d) Enhanced CT scan obtained 4 days after microwave ablation shows ablated tissue as unenhanced areas within and around the tumor (arrows). (e) Dynamic CT scan obtained 9 months after treatment shows that the lesion (arrow) has decreased in size, without evidence of new tumor growth.
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Figure 10. Photograph shows a typical solid-state laser generator.
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Figure 11a. MR imaging-guided laser ablation. (a) Photograph shows a patient positioned in an MR imaging unit (0.2-T Viva [Siemens Medical Systems, Iselin, NJ]) with the radiologist performing the procedure. (b) Sagittal MR image obtained after administration of ferumoxide contrast material shows the high-signal-intensity tumor (arrow) into which two needles (arrowheads) have been inserted.
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Figure 11b. MR imaging-guided laser ablation. (a) Photograph shows a patient positioned in an MR imaging unit (0.2-T Viva [Siemens Medical Systems, Iselin, NJ]) with the radiologist performing the procedure. (b) Sagittal MR image obtained after administration of ferumoxide contrast material shows the high-signal-intensity tumor (arrow) into which two needles (arrowheads) have been inserted.
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Figure 12a. Laser ablation of colorectal metastases. (a) MR image shows needles (arrows) positioned in a high-signal-intensity tumor (arrowheads) prior to treatment. (b) MR image shows low signal intensity (arrow) within the lesion caused by laser coagulation of the tumor.
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Figure 12b. Laser ablation of colorectal metastases. (a) MR image shows needles (arrows) positioned in a high-signal-intensity tumor (arrowheads) prior to treatment. (b) MR image shows low signal intensity (arrow) within the lesion caused by laser coagulation of the tumor.
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Figure 13a. Imaging evaluation of laser ablation of hepatocellular carcinoma. (a) Arterial-phase CT scan obtained before ablation shows a hypervascular hepatocellular carcinoma (arrow) in the right hepatic lobe. (b) Axial T2-weighted MR image obtained immediately after laser ablation shows the low-signal-intensity tumor with a high-signal-intensity rim (arrows) caused by acute peritumoral hyperemia. (c) Portal-phase CT scan obtained 24 hours after ablation shows the avascular tumor (arrow), indicating 98% ablation.
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Figure 13b. Imaging evaluation of laser ablation of hepatocellular carcinoma. (a) Arterial-phase CT scan obtained before ablation shows a hypervascular hepatocellular carcinoma (arrow) in the right hepatic lobe. (b) Axial T2-weighted MR image obtained immediately after laser ablation shows the low-signal-intensity tumor with a high-signal-intensity rim (arrows) caused by acute peritumoral hyperemia. (c) Portal-phase CT scan obtained 24 hours after ablation shows the avascular tumor (arrow), indicating 98% ablation.
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Figure 13c. Imaging evaluation of laser ablation of hepatocellular carcinoma. (a) Arterial-phase CT scan obtained before ablation shows a hypervascular hepatocellular carcinoma (arrow) in the right hepatic lobe. (b) Axial T2-weighted MR image obtained immediately after laser ablation shows the low-signal-intensity tumor with a high-signal-intensity rim (arrows) caused by acute peritumoral hyperemia. (c) Portal-phase CT scan obtained 24 hours after ablation shows the avascular tumor (arrow), indicating 98% ablation.
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Figure 14. Photograph shows a 3-cm-long, oval ice ball developing around the conductive tip of a 5-mm cryoprobe. Note that the propagation of ice is maximal perpendicular to the probe, with very little forward propagation. This necessitates that the probe tip must reach the deep edge of the lesion for optimal treatment.
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Figure 15. Photograph shows 5-mm and 10-mm penetrating cryoprobes, as well as a surface disc-type cryoprobe.
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Figure 16. Intraoperative photograph of cryoablation of a large liver tumor shows two penetrating cryoprobes (open arrows) as well as a surface disc probe
(solid straight arrow) on the opposing surface. A small intraoperative US transducer (arrowhead) and a flexible rubber "fish" (curved arrow) used to protect vital structures adjacent to the frozen liver are also seen.
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Figure 17a. US guidance of hepatic cryoablation. (a) Sonogram shows an echogenic 5-mm cryoprobe (arrow) placed centrally within a relatively isoechoic colon metastasis (arrowheads). (b) Sonogram obtained at the partial freeze stage (ie, at 3 minutes) demonstrates that the ice ball (arrow) has extended to the lateral margin of the tumor, but the anterior margin (arrowheads) is still visible. (c) Sonogram obtained at the complete freeze stage (ie, at 8 minutes) shows the ice ball (arrow), which now completely encompasses and extends beyond the anterior margin of the tumor, indicating a successful ablation.
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Figure 17b. US guidance of hepatic cryoablation. (a) Sonogram shows an echogenic 5-mm cryoprobe (arrow) placed centrally within a relatively isoechoic colon metastasis (arrowheads). (b) Sonogram obtained at the partial freeze stage (ie, at 3 minutes) demonstrates that the ice ball (arrow) has extended to the lateral margin of the tumor, but the anterior margin (arrowheads) is still visible. (c) Sonogram obtained at the complete freeze stage (ie, at 8 minutes) shows the ice ball (arrow), which now completely encompasses and extends beyond the anterior margin of the tumor, indicating a successful ablation.
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Figure 17c. US guidance of hepatic cryoablation. (a) Sonogram shows an echogenic 5-mm cryoprobe (arrow) placed centrally within a relatively isoechoic colon metastasis (arrowheads). (b) Sonogram obtained at the partial freeze stage (ie, at 3 minutes) demonstrates that the ice ball (arrow) has extended to the lateral margin of the tumor, but the anterior margin (arrowheads) is still visible. (c) Sonogram obtained at the complete freeze stage (ie, at 8 minutes) shows the ice ball (arrow), which now completely encompasses and extends beyond the anterior margin of the tumor, indicating a successful ablation.
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Figure 18a. CT evaluation of hepatic cryoablation. (a) Pretreatment CT scan shows a colorectal metastasis (arrow) in the dome of the liver that measures 3.5 cm. (b) CT scan obtained 4 days after cryoablation shows a low-attenuation cryolesion (arrow) measuring 5 x 6 cm completely encompassing the tumor site. Small gas bubbles are also seen, a finding indicative of necrosis. (c) Follow-up CT scan obtained 8 months after cryoablation shows the residual cryolesion (arrow) markedly decreased in size as a result of healing and fibrosis.
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Figure 18b. CT evaluation of hepatic cryoablation. (a) Pretreatment CT scan shows a colorectal metastasis (arrow) in the dome of the liver that measures 3.5 cm. (b) CT scan obtained 4 days after cryoablation shows a low-attenuation cryolesion (arrow) measuring 5 x 6 cm completely encompassing the tumor site. Small gas bubbles are also seen, a finding indicative of necrosis. (c) Follow-up CT scan obtained 8 months after cryoablation shows the residual cryolesion (arrow) markedly decreased in size as a result of healing and fibrosis.
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Figure 18c. CT evaluation of hepatic cryoablation. (a) Pretreatment CT scan shows a colorectal metastasis (arrow) in the dome of the liver that measures 3.5 cm. (b) CT scan obtained 4 days after cryoablation shows a low-attenuation cryolesion (arrow) measuring 5 x 6 cm completely encompassing the tumor site. Small gas bubbles are also seen, a finding indicative of necrosis. (c) Follow-up CT scan obtained 8 months after cryoablation shows the residual cryolesion (arrow) markedly decreased in size as a result of healing and fibrosis.
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Figure 19. Photograph shows ethanol ablation equipment, which consists of a syringe, sterile 95% ethanol, and a 20-cm-long, 21-gauge needle with a closed conical tip and three terminal holes (Hakko).
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Figure 20a. US guidance of ethanol ablation. (a) Pretreatment sonogram shows a 3.2-cm hepatocellular carcinoma with the tip of the treatment needle (arrow) visible in the tumor. (b) Sonogram obtained after injection of ethanol shows diffuse increase in echogenicity of the tumor (arrow).
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Figure 20b. US guidance of ethanol ablation. (a) Pretreatment sonogram shows a 3.2-cm hepatocellular carcinoma with the tip of the treatment needle (arrow) visible in the tumor. (b) Sonogram obtained after injection of ethanol shows diffuse increase in echogenicity of the tumor (arrow).
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Figure 21a. CT evaluation of ethanol ablation of hepatocellular carcinoma. (a) CT scan obtained before ablation shows an encapsulated 7-cm hepatocellular carcinoma (arrow). (b) CT scan obtained 3 years after ethanol ablation shows that the tumor (arrow) has decreased markedly in size and shows no contrast enhancement. The tumor was treated by a single-session injection of 60 mL of ethanol.
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Figure 21b. CT evaluation of ethanol ablation of hepatocellular carcinoma. (a) CT scan obtained before ablation shows an encapsulated 7-cm hepatocellular carcinoma (arrow). (b) CT scan obtained 3 years after ethanol ablation shows that the tumor (arrow) has decreased markedly in size and shows no contrast enhancement. The tumor was treated by a single-session injection of 60 mL of ethanol.
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Figure 22. Drawing shows the blood supply to the liver and hepatic tumor. The tumor derives 95% of its blood supply from the hepatic artery. Normal liver
parenchyma receives only 25% of its blood supply from the artery and the remaining 75% from the portal vein.
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Figures 23. Photograph shows embolic agents used for hepatic chemoembolization, including gelatin sponge powder (Gelfoam; Upjohn, Kalamazoo, Mich), polyvinyl alcohol particles (Interventional Therapeutics, San Francisco, Calif; Biodyne, El Cajon, Calif), and iodized poppy seed oil (Ethiodol; Savage Laboratories, Melville, NY).
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Figure 24. Photograph shows chemotherapeutic drugs used for hepatic chemoembolization, including cisplatin (Platinol), doxorubicin (Rubex), and mitomycin-C (Mutamycin) (all from Bristol-Myers Squibb Oncology, Princeton, NJ).
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Figure 25a. Chemoembolization of hepatic tumor. (a) Right hepatic arteriogram, obtained after a microcatheter has been advanced into the right hepatic artery through a 5.5-F diagnostic catheter parked in the celiac artery, demonstrates a hypervascular tumor in the posterior segment. (b) CT scan obtained before chemoembolization shows a low-attenuation hepatoma (arrow) occupying most of the posterior segment of the right hepatic lobe. (c) Postchemoembolization CT scan demonstrates a 65% reduction in tumor volume (arrow) with dense, persistent uptake and retention of the iodized oil. Oil retention correlates positively with tumor necrosis and helps predict longer survival.
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Figure 25b. Chemoembolization of hepatic tumor. (a) Right hepatic arteriogram, obtained after a microcatheter has been advanced into the right hepatic artery through a 5.5-F diagnostic catheter parked in the celiac artery, demonstrates a hypervascular tumor in the posterior segment. (b) CT scan obtained before chemoembolization shows a low-attenuation hepatoma (arrow) occupying most of the posterior segment of the right hepatic lobe. (c) Postchemoembolization CT scan demonstrates a 65% reduction in tumor volume (arrow) with dense, persistent uptake and retention of the iodized oil. Oil retention correlates positively with tumor necrosis and helps predict longer survival.
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Figure 25c. Chemoembolization of hepatic tumor. (a) Right hepatic arteriogram, obtained after a microcatheter has been advanced into the right hepatic artery through a 5.5-F diagnostic catheter parked in the celiac artery, demonstrates a hypervascular tumor in the posterior segment. (b) CT scan obtained before chemoembolization shows a low-attenuation hepatoma (arrow) occupying most of the posterior segment of the right hepatic lobe. (c) Postchemoembolization CT scan demonstrates a 65% reduction in tumor volume (arrow) with dense, persistent uptake and retention of the iodized oil. Oil retention correlates positively with tumor necrosis and helps predict longer survival.
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Copyright © 2000 by the Radiological Society of North America.
