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Hepatocellular Carcinoma Treated with Radio-frequency Ablation: Spectrum of Imaging Findings¹

¹ From the Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, South Korea. Presented as an education exhibit at the 2001 RSNA scientific assembly. Received March 13, 2002; revision requested April 25 and received June 10; accepted June 10. Address correspondence to H.K.L. (e-mail: hklim@smc.samsung.co.kr).

View larger version (160K): [in a new window]   Figure 1.  Variable echogenicity at US performed in a 45-year-old man who had undergone RF ablation for HCC. Oblique gray-scale US image of the right hepatic lobe obtained 18 hours after treatment shows a large mass with mixed echogenicity (arrows). Variable echogenicity of a mass following treatment makes it difficult to differentiate residual tumor from the necrotic portion.

View larger version (144K): [in a new window]   Figure 2a.  Successful RF ablation in a 48-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows a 1.7-cm HCC with partial contrast enhancement in segment VI of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 hour after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. (c) Contrast-enhanced power Doppler US image shows no flow signals within the ablated area, a finding that is consistent with complete tumor necrosis.

View larger version (132K): [in a new window]   Figure 2b.  Successful RF ablation in a 48-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows a 1.7-cm HCC with partial contrast enhancement in segment VI of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 hour after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. (c) Contrast-enhanced power Doppler US image shows no flow signals within the ablated area, a finding that is consistent with complete tumor necrosis.

View larger version (162K): [in a new window]   Figure 2c.  Successful RF ablation in a 48-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows a 1.7-cm HCC with partial contrast enhancement in segment VI of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 hour after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. (c) Contrast-enhanced power Doppler US image shows no flow signals within the ablated area, a finding that is consistent with complete tumor necrosis.

View larger version (142K): [in a new window]   Figure 3a.  Residual tumor in a 72-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC in segment VI of the liver (arrows). (b) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 2 hours after RF ablation, most of the ablated area (arrows) has low attenuation, but a focal crescentic enhancing portion (arrowheads) is noted at the medial aspect of the ablated area. Nodular enhancement representing residual viable tumor is also noted. (c) Contrast-enhanced power Doppler US image obtained 18 hours after RF ablation shows focal flow signals (arrowheads) that represent residual tumor vessels within the ablated area (arrows). The residual tumor was treated with repeat RF ablation later the same day.

View larger version (126K): [in a new window]   Figure 3b.  Residual tumor in a 72-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC in segment VI of the liver (arrows). (b) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 2 hours after RF ablation, most of the ablated area (arrows) has low attenuation, but a focal crescentic enhancing portion (arrowheads) is noted at the medial aspect of the ablated area. Nodular enhancement representing residual viable tumor is also noted. (c) Contrast-enhanced power Doppler US image obtained 18 hours after RF ablation shows focal flow signals (arrowheads) that represent residual tumor vessels within the ablated area (arrows). The residual tumor was treated with repeat RF ablation later the same day.

View larger version (189K): [in a new window]   Figure 3c.  Residual tumor in a 72-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC in segment VI of the liver (arrows). (b) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 2 hours after RF ablation, most of the ablated area (arrows) has low attenuation, but a focal crescentic enhancing portion (arrowheads) is noted at the medial aspect of the ablated area. Nodular enhancement representing residual viable tumor is also noted. (c) Contrast-enhanced power Doppler US image obtained 18 hours after RF ablation shows focal flow signals (arrowheads) that represent residual tumor vessels within the ablated area (arrows). The residual tumor was treated with repeat RF ablation later the same day.

View larger version (135K): [in a new window]   Figure 4a.  Successful RF ablation in a 63-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.3-cm HCC in the subcapsular portion of segment VII of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique before RF ablation shows the tumor with homogeneous enhancement (arrows). Note also the feeding hepatic artery (arrowheads). (c) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows that the ablated lesion has become avascular (arrows). (d) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (161K): [in a new window]   Figure 4b.  Successful RF ablation in a 63-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.3-cm HCC in the subcapsular portion of segment VII of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique before RF ablation shows the tumor with homogeneous enhancement (arrows). Note also the feeding hepatic artery (arrowheads). (c) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows that the ablated lesion has become avascular (arrows). (d) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (156K): [in a new window]   Figure 4c.  Successful RF ablation in a 63-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.3-cm HCC in the subcapsular portion of segment VII of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique before RF ablation shows the tumor with homogeneous enhancement (arrows). Note also the feeding hepatic artery (arrowheads). (c) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows that the ablated lesion has become avascular (arrows). (d) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (135K): [in a new window]   Figure 4d.  Successful RF ablation in a 63-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.3-cm HCC in the subcapsular portion of segment VII of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique before RF ablation shows the tumor with homogeneous enhancement (arrows). Note also the feeding hepatic artery (arrowheads). (c) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows that the ablated lesion has become avascular (arrows). (d) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (153K): [in a new window]   Figure 5a.  Residual tumor in a 78-year-old woman with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.1-cm HCC in segment III of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows nodular enhancement (arrowheads) that represents untreated residual tumor at the posterior aspect of the ablated area (arrows). (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation also demonstrates nodular enhancement (arrowheads) at the posterior aspect of the ablated area (arrows). The residual tumor was treated with repeat RF ablation.

View larger version (163K): [in a new window]   Figure 5b.  Residual tumor in a 78-year-old woman with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.1-cm HCC in segment III of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows nodular enhancement (arrowheads) that represents untreated residual tumor at the posterior aspect of the ablated area (arrows). (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation also demonstrates nodular enhancement (arrowheads) at the posterior aspect of the ablated area (arrows). The residual tumor was treated with repeat RF ablation.

View larger version (149K): [in a new window]   Figure 5c.  Residual tumor in a 78-year-old woman with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.1-cm HCC in segment III of the liver (arrows). (b) Contrast-enhanced gray-scale US image obtained with a coded harmonic angiographic technique 19 hours after RF ablation shows nodular enhancement (arrowheads) that represents untreated residual tumor at the posterior aspect of the ablated area (arrows). (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation also demonstrates nodular enhancement (arrowheads) at the posterior aspect of the ablated area (arrows). The residual tumor was treated with repeat RF ablation.

View larger version (133K): [in a new window]   Figure 6a.  Successful RF ablation in a 70-year-old woman with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows a partially enhancing 3.1-cm HCC in segment VIII of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase CT scan obtained immediately after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete necrosis of the tumor. Note also the hyperemia surrounding the tumor (arrowheads). (c) On an axial follow-up CT scan obtained 17 months later, the ablated lesion (arrows) remains unenhanced and shows an interval decrease in size.

View larger version (135K): [in a new window]   Figure 6b.  Successful RF ablation in a 70-year-old woman with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows a partially enhancing 3.1-cm HCC in segment VIII of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase CT scan obtained immediately after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete necrosis of the tumor. Note also the hyperemia surrounding the tumor (arrowheads). (c) On an axial follow-up CT scan obtained 17 months later, the ablated lesion (arrows) remains unenhanced and shows an interval decrease in size.

View larger version (123K): [in a new window]   Figure 6c.  Successful RF ablation in a 70-year-old woman with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows a partially enhancing 3.1-cm HCC in segment VIII of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase CT scan obtained immediately after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete necrosis of the tumor. Note also the hyperemia surrounding the tumor (arrowheads). (c) On an axial follow-up CT scan obtained 17 months later, the ablated lesion (arrows) remains unenhanced and shows an interval decrease in size.

View larger version (118K): [in a new window]   Figure 7a.  Successful RF ablation in a 64-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 1.5-cm HCC in segment V of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. Note that the ablated lesion is much larger than the enhancing tumor (cf a), which indicates that there is a sufficient safety margin.

View larger version (108K): [in a new window]   Figure 7b.  Successful RF ablation in a 64-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 1.5-cm HCC in segment V of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. Note that the ablated lesion is much larger than the enhancing tumor (cf a), which indicates that there is a sufficient safety margin.

View larger version (116K): [in a new window]   Figure 8a.  Residual tumor in a 59-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 2-cm HCC in segment VII of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows nodular enhancement (arrowheads) at the posterior aspect of the ablated lesion (arrows). The enhancing nodule was thought to represent residual viable tumor and was treated with repeat RF ablation. (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after repeat RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete necrosis of the tumor.

View larger version (119K): [in a new window]   Figure 8b.  Residual tumor in a 59-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 2-cm HCC in segment VII of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows nodular enhancement (arrowheads) at the posterior aspect of the ablated lesion (arrows). The enhancing nodule was thought to represent residual viable tumor and was treated with repeat RF ablation. (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after repeat RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete necrosis of the tumor.

View larger version (135K): [in a new window]   Figure 8c.  Residual tumor in a 59-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 2-cm HCC in segment VII of the liver (arrows). (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows nodular enhancement (arrowheads) at the posterior aspect of the ablated lesion (arrows). The enhancing nodule was thought to represent residual viable tumor and was treated with repeat RF ablation. (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after repeat RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete necrosis of the tumor.

View larger version (126K): [in a new window]   Figure 9a.  Residual tumor in a 49-year-old man with a 3-cm HCC in segment VIII of the liver. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 4 months after RF ablation shows nodular enhancement (arrowheads) at the lateral aspect of the ablated lesion (arrows). (b) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 6 months after RF ablation, the enhancing nodule (arrowheads) demonstrates an interval increase in size (cf a). The nodule was thought to represent residual viable tumor and was treated with repeat RF ablation. Arrows indicate the ablated lesion. (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 3 months after repeat RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (132K): [in a new window]   Figure 9b.  Residual tumor in a 49-year-old man with a 3-cm HCC in segment VIII of the liver. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 4 months after RF ablation shows nodular enhancement (arrowheads) at the lateral aspect of the ablated lesion (arrows). (b) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 6 months after RF ablation, the enhancing nodule (arrowheads) demonstrates an interval increase in size (cf a). The nodule was thought to represent residual viable tumor and was treated with repeat RF ablation. Arrows indicate the ablated lesion. (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 3 months after repeat RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (133K): [in a new window]   Figure 9c.  Residual tumor in a 49-year-old man with a 3-cm HCC in segment VIII of the liver. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 4 months after RF ablation shows nodular enhancement (arrowheads) at the lateral aspect of the ablated lesion (arrows). (b) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 6 months after RF ablation, the enhancing nodule (arrowheads) demonstrates an interval increase in size (cf a). The nodule was thought to represent residual viable tumor and was treated with repeat RF ablation. Arrows indicate the ablated lesion. (c) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 3 months after repeat RF ablation shows an unenhanced oval ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis.

View larger version (111K): [in a new window]   Figure 10a.  Reactive hyperemia in a 76-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC with central uptake of iodized oil (Lipiodol; Guerbet, Roissy, France) in segment VIII of the liver (arrows). (b, c) Axial contrast-enhanced hepatic arterial phase (b) and portal venous phase (c) helical CT scans obtained 20 minutes after RF ablation demonstrate uniform rim enhancement (arrows) surrounding the ablated lesion. (d) On an axial equilibrium phase helical CT scan, the rim enhancement is isoattenuating (arrows). (e) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation, the rim enhancement is no longer seen, a finding that helps confirm the diagnosis of reactive hyperemia.

View larger version (117K): [in a new window]   Figure 10b.  Reactive hyperemia in a 76-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC with central uptake of iodized oil (Lipiodol; Guerbet, Roissy, France) in segment VIII of the liver (arrows). (b, c) Axial contrast-enhanced hepatic arterial phase (b) and portal venous phase (c) helical CT scans obtained 20 minutes after RF ablation demonstrate uniform rim enhancement (arrows) surrounding the ablated lesion. (d) On an axial equilibrium phase helical CT scan, the rim enhancement is isoattenuating (arrows). (e) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation, the rim enhancement is no longer seen, a finding that helps confirm the diagnosis of reactive hyperemia.

View larger version (122K): [in a new window]   Figure 10c.  Reactive hyperemia in a 76-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC with central uptake of iodized oil (Lipiodol; Guerbet, Roissy, France) in segment VIII of the liver (arrows). (b, c) Axial contrast-enhanced hepatic arterial phase (b) and portal venous phase (c) helical CT scans obtained 20 minutes after RF ablation demonstrate uniform rim enhancement (arrows) surrounding the ablated lesion. (d) On an axial equilibrium phase helical CT scan, the rim enhancement is isoattenuating (arrows). (e) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation, the rim enhancement is no longer seen, a finding that helps confirm the diagnosis of reactive hyperemia.

View larger version (120K): [in a new window]   Figure 10d.  Reactive hyperemia in a 76-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC with central uptake of iodized oil (Lipiodol; Guerbet, Roissy, France) in segment VIII of the liver (arrows). (b, c) Axial contrast-enhanced hepatic arterial phase (b) and portal venous phase (c) helical CT scans obtained 20 minutes after RF ablation demonstrate uniform rim enhancement (arrows) surrounding the ablated lesion. (d) On an axial equilibrium phase helical CT scan, the rim enhancement is isoattenuating (arrows). (e) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation, the rim enhancement is no longer seen, a finding that helps confirm the diagnosis of reactive hyperemia.

View larger version (110K): [in a new window]   Figure 10e.  Reactive hyperemia in a 76-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained before RF ablation shows an enhancing 3.5-cm HCC with central uptake of iodized oil (Lipiodol; Guerbet, Roissy, France) in segment VIII of the liver (arrows). (b, c) Axial contrast-enhanced hepatic arterial phase (b) and portal venous phase (c) helical CT scans obtained 20 minutes after RF ablation demonstrate uniform rim enhancement (arrows) surrounding the ablated lesion. (d) On an axial equilibrium phase helical CT scan, the rim enhancement is isoattenuating (arrows). (e) On an axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation, the rim enhancement is no longer seen, a finding that helps confirm the diagnosis of reactive hyperemia.

View larger version (131K): [in a new window]   Figure 11a.  Iatrogenic arteriovenous shunting in a 36-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 15 minutes after RF ablation shows two unenhanced oval ablated areas with low attenuation (arrows). (b) Axial contrast-enhanced helical CT scan obtained caudad to a shows a wedge-shaped area of enhancement (arrows) that represents iatrogenic arteriovenous shunting at the posterolateral aspect of the ablated lesion. Note the early visualization of the portal vein branch (arrowheads).

View larger version (121K): [in a new window]   Figure 11b.  Iatrogenic arteriovenous shunting in a 36-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 15 minutes after RF ablation shows two unenhanced oval ablated areas with low attenuation (arrows). (b) Axial contrast-enhanced helical CT scan obtained caudad to a shows a wedge-shaped area of enhancement (arrows) that represents iatrogenic arteriovenous shunting at the posterolateral aspect of the ablated lesion. Note the early visualization of the portal vein branch (arrowheads).

View larger version (157K): [in a new window]   Figure 12a.  Air formation in a 55-year-old man with HCC. (a) Axial contrast-enhanced helical CT scan obtained 15 minutes after RF ablation shows an ablated lesion (arrows) that contains small air pockets (arrowheads). (b) Axial follow-up helical CT scan shows resolution of the air pockets.

View larger version (148K): [in a new window]   Figure 12b.  Air formation in a 55-year-old man with HCC. (a) Axial contrast-enhanced helical CT scan obtained 15 minutes after RF ablation shows an ablated lesion (arrows) that contains small air pockets (arrowheads). (b) Axial follow-up helical CT scan shows resolution of the air pockets.

View larger version (107K): [in a new window]   Figure 13a.  Successful RF ablation in a 49-year-old man with HCC. (a) Axial spin-echo T1-weighted MR image obtained 1 month after RF ablation shows an oval ablated area (arrows) that is isointense relative to the surrounding liver parenchyma. (b) Axial spin-echo T2-weighted MR image again shows the oval ablated area (arrows) as isointense relative to the surrounding liver parenchyma. Note the high-signal-intensity rim, a finding that represents reactive change. (c) Axial gradient-echo T1-weighted MR image obtained immediately after the administration of gadolinium chelates shows an unenhanced oval ablated area (arrows) that is isointense relative to the surrounding liver parenchyma, a finding that suggests complete tumor necrosis.

View larger version (110K): [in a new window]   Figure 13b.  Successful RF ablation in a 49-year-old man with HCC. (a) Axial spin-echo T1-weighted MR image obtained 1 month after RF ablation shows an oval ablated area (arrows) that is isointense relative to the surrounding liver parenchyma. (b) Axial spin-echo T2-weighted MR image again shows the oval ablated area (arrows) as isointense relative to the surrounding liver parenchyma. Note the high-signal-intensity rim, a finding that represents reactive change. (c) Axial gradient-echo T1-weighted MR image obtained immediately after the administration of gadolinium chelates shows an unenhanced oval ablated area (arrows) that is isointense relative to the surrounding liver parenchyma, a finding that suggests complete tumor necrosis.

View larger version (107K): [in a new window]   Figure 13c.  Successful RF ablation in a 49-year-old man with HCC. (a) Axial spin-echo T1-weighted MR image obtained 1 month after RF ablation shows an oval ablated area (arrows) that is isointense relative to the surrounding liver parenchyma. (b) Axial spin-echo T2-weighted MR image again shows the oval ablated area (arrows) as isointense relative to the surrounding liver parenchyma. Note the high-signal-intensity rim, a finding that represents reactive change. (c) Axial gradient-echo T1-weighted MR image obtained immediately after the administration of gadolinium chelates shows an unenhanced oval ablated area (arrows) that is isointense relative to the surrounding liver parenchyma, a finding that suggests complete tumor necrosis.

View larger version (98K): [in a new window]   Figure 14a.  Marginal recurrent tumor in a 49-year-old man with HCC. (a) Axial spin-echo T1-weighted MR image obtained 7 months after RF ablation shows an oval ablated area with slightly increased signal intensity (arrows). (b) Axial spin-echo T2-weighted MR image shows a small nodular lesion with high signal intensity (arrowheads) at the anterior aspect of the low-signal-intensity ablated lesion (arrows). (c) Axial gradient-echo T1-weighted MR image obtained immediately after the administration of gadolinium chelates shows a small enhancing nodule (arrowheads) that represents marginal recurrent tumor at the anterior aspect of the ablated lesion (arrows). The recurrent tumor was treated with repeat RF ablation.

View larger version (130K): [in a new window]   Figure 14b.  Marginal recurrent tumor in a 49-year-old man with HCC. (a) Axial spin-echo T1-weighted MR image obtained 7 months after RF ablation shows an oval ablated area with slightly increased signal intensity (arrows). (b) Axial spin-echo T2-weighted MR image shows a small nodular lesion with high signal intensity (arrowheads) at the anterior aspect of the low-signal-intensity ablated lesion (arrows). (c) Axial gradient-echo T1-weighted MR image obtained immediately after the administration of gadolinium chelates shows a small enhancing nodule (arrowheads) that represents marginal recurrent tumor at the anterior aspect of the ablated lesion (arrows). The recurrent tumor was treated with repeat RF ablation.

View larger version (112K): [in a new window]   Figure 14c.  Marginal recurrent tumor in a 49-year-old man with HCC. (a) Axial spin-echo T1-weighted MR image obtained 7 months after RF ablation shows an oval ablated area with slightly increased signal intensity (arrows). (b) Axial spin-echo T2-weighted MR image shows a small nodular lesion with high signal intensity (arrowheads) at the anterior aspect of the low-signal-intensity ablated lesion (arrows). (c) Axial gradient-echo T1-weighted MR image obtained immediately after the administration of gadolinium chelates shows a small enhancing nodule (arrowheads) that represents marginal recurrent tumor at the anterior aspect of the ablated lesion (arrows). The recurrent tumor was treated with repeat RF ablation.

View larger version (129K): [in a new window]   Figure 15a.  Hepatic abscess in a 69-year-old man with HCC. (a) Axial contrast-enhanced helical CT scan obtained 4 days after RF ablation shows an ablated lesion with an oval, mottled air-containing abscess cavity (arrows). The abscess cavity was treated with percutaneous catheter drainage and antibiotics. (b) Axial follow-up helical CT scan obtained 12 months later shows complete resolution of the abscess cavity.

View larger version (147K): [in a new window]   Figure 15b.  Hepatic abscess in a 69-year-old man with HCC. (a) Axial contrast-enhanced helical CT scan obtained 4 days after RF ablation shows an ablated lesion with an oval, mottled air-containing abscess cavity (arrows). The abscess cavity was treated with percutaneous catheter drainage and antibiotics. (b) Axial follow-up helical CT scan obtained 12 months later shows complete resolution of the abscess cavity.

View larger version (136K): [in a new window]   Figure 16a.  Needle track seeding in a 54-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 16 months after RF ablation shows a 3-cm soft-tissue lesion (arrowheads) abutting the falciform ligament at the anterior aspect of the ablated lesion (arrows). The lesion was surgically confirmed to represent needle track seeding in the perihepatic space resulting from RF ablation.

View larger version (140K): [in a new window]   Figure 16b.  Needle track seeding in a 54-year-old man with HCC. (a) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 1 month after RF ablation shows an unenhanced round ablated area with low attenuation (arrows), a finding that suggests complete tumor necrosis. (b) Axial contrast-enhanced hepatic arterial phase helical CT scan obtained 16 months after RF ablation shows a 3-cm soft-tissue lesion (arrowheads) abutting the falciform ligament at the anterior aspect of the ablated lesion (arrows). The lesion was surgically confirmed to represent needle track seeding in the perihepatic space resulting from RF ablation.

View larger version (129K): [in a new window]   Figure 17a.  Biloma in a 54-year-old man with HCC. (a) Axial unenhanced helical CT scan obtained 1 month after RF ablation shows an ablated tumor (arrow) with slightly increased attenuation and surrounded by a fluid collection (arrowheads). (b) US image obtained the same day also shows the fluid collection (arrowheads) surrounding the ablated tissue (arrow). (c) Endoscopic retrograde cholangiopancreatogram obtained the same day shows contrast material within the ablated area (arrows), a finding that represents communication with the bile duct and biloma formation. (d) On an axial unenhanced helical CT scan obtained immediately after endoscopic retrograde cholangiopancreatography, the ablated lesion contains a collection of contrast material (arrows) and is surrounded by air pockets (arrowheads). The lesion was treated conservatively.

View larger version (119K): [in a new window]   Figure 17b.  Biloma in a 54-year-old man with HCC. (a) Axial unenhanced helical CT scan obtained 1 month after RF ablation shows an ablated tumor (arrow) with slightly increased attenuation and surrounded by a fluid collection (arrowheads). (b) US image obtained the same day also shows the fluid collection (arrowheads) surrounding the ablated tissue (arrow). (c) Endoscopic retrograde cholangiopancreatogram obtained the same day shows contrast material within the ablated area (arrows), a finding that represents communication with the bile duct and biloma formation. (d) On an axial unenhanced helical CT scan obtained immediately after endoscopic retrograde cholangiopancreatography, the ablated lesion contains a collection of contrast material (arrows) and is surrounded by air pockets (arrowheads). The lesion was treated conservatively.

View larger version (116K): [in a new window]   Figure 17c.  Biloma in a 54-year-old man with HCC. (a) Axial unenhanced helical CT scan obtained 1 month after RF ablation shows an ablated tumor (arrow) with slightly increased attenuation and surrounded by a fluid collection (arrowheads). (b) US image obtained the same day also shows the fluid collection (arrowheads) surrounding the ablated tissue (arrow). (c) Endoscopic retrograde cholangiopancreatogram obtained the same day shows contrast material within the ablated area (arrows), a finding that represents communication with the bile duct and biloma formation. (d) On an axial unenhanced helical CT scan obtained immediately after endoscopic retrograde cholangiopancreatography, the ablated lesion contains a collection of contrast material (arrows) and is surrounded by air pockets (arrowheads). The lesion was treated conservatively.

View larger version (110K): [in a new window]   Figure 17d.  Biloma in a 54-year-old man with HCC. (a) Axial unenhanced helical CT scan obtained 1 month after RF ablation shows an ablated tumor (arrow) with slightly increased attenuation and surrounded by a fluid collection (arrowheads). (b) US image obtained the same day also shows the fluid collection (arrowheads) surrounding the ablated tissue (arrow). (c) Endoscopic retrograde cholangiopancreatogram obtained the same day shows contrast material within the ablated area (arrows), a finding that represents communication with the bile duct and biloma formation. (d) On an axial unenhanced helical CT scan obtained immediately after endoscopic retrograde cholangiopancreatography, the ablated lesion contains a collection of contrast material (arrows) and is surrounded by air pockets (arrowheads). The lesion was treated conservatively.