- Email: [email protected]
Abstract No. 355: Early CT appearance of hepatic ablation zones following irreversible electroporation
Poster Sessions 䡲 JVIR
S142
- To highlight advantages and disadvantages of IRE in treating liver tumors - To illustrate post procedural imaging characteristics - To draw attention to post procedural complications Background: IRE is based on the theory that applied voltage gradients across cells increase membrane permeability. Subsequent cell death arises from an inability to maintain membrane integrity and a voltage gradient. IRE has minimal temperature effects on tissues compared with thermal ablation. IRE of liver tumors can cause cell death in adjacent bowel, biliary duct and vessels. However, the process does not damage collagen and elastin fibers in these tissues. Post-procedural complications specific to IRE include liver trauma (laceration, probe dislodgement), cardiac arrhythmias, and an autoimmune response. Currently, immediate post-procedural imaging is limited in that CT overestimates the ablation zone and MR is incompatible with current ablation equipment. Subsequent follow-up imaging is useful in determining treatment response. Clinical Findings/Procedure Details: - Biopsy of lesion (when appropriate) - Hydrodissection or gas dissection of the area (if needed) - Positioning of electrodes around the area of interest [minimum of 2 probes required with parallel spacing of 1.5 cm to 1.9 cm apart (with current design); electric field mapped] - Electrode test and delivery of voltage gradient - Post-procedure scan to evaluate for bleeding and other complications Conclusion and/or Teaching Points: IRE is a promising, unique, nonthermal ablation technique for treating tumors that preserves collagen/elastin structure and is not susceptible to a heat sink. Preservation of protein structure has the advantage of maintaining structures near the ablation site (gallbladder/bile ducts/ nerve sheaths). The procedure is not without cardiac, traumatic, and autoimmune responses. Additionally, there are currently no effective imaging modalities to monitor ablation immediately post-procedure. IRE efficacy, long term results, and complication rates need to be further evaluated in a multicenter randomized study.
Abstract No. 354 The impact of variation in portal venous blood flow on the size of radiofrequency and microwave ablation lesions in in-vitro blood perfused bovine livers
Poster Sessions
G.D. Dodd, III, N.A. Dodd, A.C. Lanctot; Radiology, University of Colorado Denver HSC SOM, Aurora, CO Purpose: To assess the impact of variation in portal venous flow on the size of radiofrequency (RF) and microwave (MW) ablation lesions in in-vitro blood perfused bovine livers. Materials and Methods: 60 ablations (2 MW and 2 RF ablations/liver) were performed in 15 bovine livers perfused with autologous blood via the portal vein at 60, 70, 80, 90, and 100 ml/min/100g liver (3 livers/flow rate). Length, width, and volume were measured/calculated for each ablation lesion.
Results: The mean ablation volumes for the 5 flow rates (low to high) were 12.54, 8.00, 5.41, 5.31, and 3.72 for RF, and 22.00, 21.30, 22.37, 22.61, and 21.66 for MW, respectively. The slopes were ⫺0.204 ⫾ 0.03 (Sy.x ⫽ 2.23, F ⫽ 50.54, p ⬍ 0.0001) for RF, and 0.006⫾ 0.018 (Sy.x ⫽ 1.397, F⫽0.11, p ⫽ 0.75) for MW. Conclusion: The size of RF ablation lesions is highly variable with a statistically significant inverse relationship to the rate of portal venous blood flow; conversely, the size of MW ablation lesions is unperturbed by changes in portal venous blood flow. The consistency of the size of MW ablation lesions could translate into a higher local tumor eradication rate than reported with RF ablation.
Abstract No. 355 Early CT appearance of hepatic ablation zones following irreversible electroporation L. Findeiss1,2, L. Dansby1; 1Radiological Sciences, University of California at Irvine, Orange, CA; 2Surgery, University of California at Irvine, Orange, CA Purpose: To evaluate the natural progression of imaging findings following irreversible electroporation in the liver, specifically focusing on the early CT appearance of ablation zones. Materials and Methods: We performed retrospective review of eight consecutive patients with 9 liver tumors treated with irreversible electroporation. Review was under an existing IRB. Probe placement was governed by lesion size and prescribed by the ablation device computer algorithm (Nanoknife, AngioDynamics). Expected ablation size was calculated based on interprobe distance. All patients underwent CT with IV contrast on POD #1 or 2. Pre-ablation lesion sizes and post-procedure ablation zones were measured in three dimensions and volumes calculated using the formula for an ellipse. Ablation zones were also characterized qualitatively. Results: After the review, 2 tumors were discarded. Mean calculated ablation zone size was 24.7 cm 3, and mean volumes of hypodense and surrounding hyperemic ablation zones on early postoperative CT were 26.1 cm 3 and 42.1 cm 3, respectively. On late postablation imaging, mean volumes were 11.9 cm 3 and 15.2 cm 3, respectively. Three distinct post-ablation contrast enhancement patterns were observed, and one distinct pattern was associated with failure of ablation. Conclusion: In our retrospective series, we have observed an apparent ablation zone on early post-ablation imaging that can be variable in appearance. When hypodense and hyperemic zones are taken together, these ablation zones are larger than the ablation zones predicted by the device computer algorithm. This observation contradicts the nearly 1:1 correlation of imaging:histology ablation zone sizes observed in animal studies. It appears that the qualitative appearance of ablation zones on early post-operative imaging may predict success.
JVIR 䡲 Poster Sessions
S143
Ablation Zone Predicted and Actual
Lesion Size
Lesion Type
Calculated Ablation Zone Volume
1.4 x 1.0 x 1.3 cm 2.4 x 1.3 x 3.0 cm
Rectal Metastasis Colon Metastasis
28.7 cm 3 58.9 cm 3
1600 V/cm 1600 V/cm
1 1
17.0 cm 3 / 25.8 cm 3 20.9 cm 3 / 38.9 cm 3
2.0 x 0.8 x 0.5 cm 1.2 x 1.3 x 0.6 cm
HCC HCC
4.8 cm 3 5.6 cm 3
1824 V/cm 1972 V/cm
1 1
13.3 cm 3 / 0 10.3 cm 3 / 0
2.1 x 1.8 x 2.3 cm
Colon Metastasis
15.0 cm 3
1900 V/cm
1
2.1 x 2.2 x 1.7 cm
Colon Metastasis
35.0 cm 3
2000 V/cm
2
Power Delivered
Time to CT 1 (Days)
Ablation Zone Size Hypo/Hyper
Time to CT 2 (Days)
Ablation Zone Size Hypo/Hyper
9 6
23.7 cm 3 / 0 21.6 cm 3 / 33.2 cm 3 0.3 cm 3/ 0 1.5 cm 3 / 4.1 cm 3 3.7 cm 3 / 9.7 cm 3 20.7 cm 3 / 0
Abstract No. 356 Subxyphoid liver biopsy risk of pericardial tamponade: a CT anatomic study R.S. Florek1, F. Kushner2; 1Radiology, Lourdes Regional Medical Center, Lafayette, LA; 2Cardiology, West Jefferson Medical Center, Marrero, LA Purpose: Subxyphoid liver biopsy entails the risk of pericardial injury and tamponade. A review of 1127 therapeutic pericardiocenteses shows the risk of pericardial tamponade is increasing with the increasing number of thoracic interventions (1, 2). Pericardiocentesis can be performed if this complication is recognized (3). A PIAA review (4) of eleven cases of subxyphoid liver biopsy induced tamponade found one successful recognition and emergent pericardiocentesis, the patient survived and is doing well 3 yrs. later. The other 10 died. Awareness of this complication risk should increase the successful salvage rate. Materials and Methods: The level of the pericardium (PC) relative to the xyphoid tip was assessed in 100 sequential CT scans. Midline sagittal images were used to measure the location of the pericardium (PC) in the supine (biopsy) position to the lower tip of the xyphoid. CT scans were scored into 3 groups: Group A pc ⬎2cm above tip of the xyphoid; Group B 0 –2cm above; and Group C below the xyphoid. Results: Of the CT scans reviewed, 68% showed the pc to be greater than 2cm above the xyphoid tip; 20% were 0 –2 cm above the xyphoid tip; and in 12% the heart was below the tip of the xyphoid, indicating greatest risk of pericardial perforation. Conclusion: The risk of pericardial perforation during a subxyphoid liver biopsy increases with lower position of the heart. Assessment of the subxyphoid access window will be helpful in planning risk of the subxyphoid liver biopsy. References
Educational Exhibit
Abstract No. 357
Effective targeting of hepatic dome lesions during CT guided ablation procedures
88.4 cm 3 / 0
26 33
G.A. Franco, R.S. Williams, D.D. Kies, T.M. Fahrbach, J.F. Hart, J. Martin, M.K. Ford, H.S. Kim; Interventional Radiology, Emory Healthcare, Atlanta, GA Learning Objectives: To illustrate with the aid of diagrams and cross sectional imaging, a fast and effective approach to probe placement by using the “safe plane approach” method to historically difficult hepatic dome lesions. Background: Ablative technologies have advanced significantly over the past 2 decades. While there are many imaging modalities, CT and US remain the most commonly used. CT has numerous advantages over US. However, certain lesions remain difficult to target by CT. One such lesion is the hepatic dome lesion. Historically, hepatic dome lesions were accessed via a transthoracic approach, with ultrasound assistance or worse, deemed nonablatable. At our institution, we have implemented a fast and effective method to accurately place ablation probes within these difficult to treat hepatic dome lesion. Clinical Findings/Procedure Details: Initial evaluation: Review prior cross sectional imaging assessing lesion proximity to adjacent structures including vessel, Gleason’s capsule and the diaphragm. Evaluate for ascites and understand the background liver parenchyma. Procedure: The patient is placed supine/head first on the gantry and an initial CT is obtained through the liver with cutaneous markers in quiet respiration. The hepatic dome lesion is localized in the axial plane and 25 g needle is placed in the anterior abdominal wall corresponding to the axial and sagittal coordinates. A second needle is placed in the lateral abdominal wall corresponding to the coronal plane at the ablation probe skin entry site (usually 9th through 11th ribs). Skin entry site is chosen based on the safest/most effective probe course. The skin to lesion distance is measured and the ablation probe is advanced in the direction of the anterior abdominal needle from the skin entry site always being held parallel to the floor. This procedure limits the amount of repeat imaging saving time and radiation. A limited CT or CT fluoroscopy is used to make subtle adjustments in probe position. Once the probe is well position, the ablation is performed. Conclusion and/or Teaching Points: Effective CT guided ablation of historically difficult hepatic dome lesions can be achieved using the “safe plane approach”.
Abstract No. 358 Safety and tolerability of two dosing regimens of sorafenib in combination with locoregional therapy in patients with hepatocellular carcinoma
Poster Sessions
1. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical outcomes spanning 21 years. Tsang TS, Enriquez-Sarano M. Mayo Clin Proc. 2002 May;77(5):429-36. 2. Iatrogenic pericardial effusion and tamponade in the percutaneous intracardiac intervention era. Holmes DR, Nishimura R. JACC Cardiovasc Interv. 2009 Aug:2(8):705-17. 3. Rescue echocardiographically guided pericardiocentesis for cardiac perforation complicating catheter-based procedures. The Mayo Clinic Experience. Tsang TS, Freeman WK. J Am Coll Cardiol. 1998 Nov;32(5): 1345-50. 4. PIAA: Physicians Insurance Association of America: 2009 Review. United States. Pericardial tamponade from subxyphoid liver biopsy.
6.6 cm 3 / 76.2 cm 3
69 69
S142
- To highlight advantages and disadvantages of IRE in treating liver tumors - To illustrate post procedural imaging characteristics - To draw attention to post procedural complications Background: IRE is based on the theory that applied voltage gradients across cells increase membrane permeability. Subsequent cell death arises from an inability to maintain membrane integrity and a voltage gradient. IRE has minimal temperature effects on tissues compared with thermal ablation. IRE of liver tumors can cause cell death in adjacent bowel, biliary duct and vessels. However, the process does not damage collagen and elastin fibers in these tissues. Post-procedural complications specific to IRE include liver trauma (laceration, probe dislodgement), cardiac arrhythmias, and an autoimmune response. Currently, immediate post-procedural imaging is limited in that CT overestimates the ablation zone and MR is incompatible with current ablation equipment. Subsequent follow-up imaging is useful in determining treatment response. Clinical Findings/Procedure Details: - Biopsy of lesion (when appropriate) - Hydrodissection or gas dissection of the area (if needed) - Positioning of electrodes around the area of interest [minimum of 2 probes required with parallel spacing of 1.5 cm to 1.9 cm apart (with current design); electric field mapped] - Electrode test and delivery of voltage gradient - Post-procedure scan to evaluate for bleeding and other complications Conclusion and/or Teaching Points: IRE is a promising, unique, nonthermal ablation technique for treating tumors that preserves collagen/elastin structure and is not susceptible to a heat sink. Preservation of protein structure has the advantage of maintaining structures near the ablation site (gallbladder/bile ducts/ nerve sheaths). The procedure is not without cardiac, traumatic, and autoimmune responses. Additionally, there are currently no effective imaging modalities to monitor ablation immediately post-procedure. IRE efficacy, long term results, and complication rates need to be further evaluated in a multicenter randomized study.
Abstract No. 354 The impact of variation in portal venous blood flow on the size of radiofrequency and microwave ablation lesions in in-vitro blood perfused bovine livers
Poster Sessions
G.D. Dodd, III, N.A. Dodd, A.C. Lanctot; Radiology, University of Colorado Denver HSC SOM, Aurora, CO Purpose: To assess the impact of variation in portal venous flow on the size of radiofrequency (RF) and microwave (MW) ablation lesions in in-vitro blood perfused bovine livers. Materials and Methods: 60 ablations (2 MW and 2 RF ablations/liver) were performed in 15 bovine livers perfused with autologous blood via the portal vein at 60, 70, 80, 90, and 100 ml/min/100g liver (3 livers/flow rate). Length, width, and volume were measured/calculated for each ablation lesion.
Results: The mean ablation volumes for the 5 flow rates (low to high) were 12.54, 8.00, 5.41, 5.31, and 3.72 for RF, and 22.00, 21.30, 22.37, 22.61, and 21.66 for MW, respectively. The slopes were ⫺0.204 ⫾ 0.03 (Sy.x ⫽ 2.23, F ⫽ 50.54, p ⬍ 0.0001) for RF, and 0.006⫾ 0.018 (Sy.x ⫽ 1.397, F⫽0.11, p ⫽ 0.75) for MW. Conclusion: The size of RF ablation lesions is highly variable with a statistically significant inverse relationship to the rate of portal venous blood flow; conversely, the size of MW ablation lesions is unperturbed by changes in portal venous blood flow. The consistency of the size of MW ablation lesions could translate into a higher local tumor eradication rate than reported with RF ablation.
Abstract No. 355 Early CT appearance of hepatic ablation zones following irreversible electroporation L. Findeiss1,2, L. Dansby1; 1Radiological Sciences, University of California at Irvine, Orange, CA; 2Surgery, University of California at Irvine, Orange, CA Purpose: To evaluate the natural progression of imaging findings following irreversible electroporation in the liver, specifically focusing on the early CT appearance of ablation zones. Materials and Methods: We performed retrospective review of eight consecutive patients with 9 liver tumors treated with irreversible electroporation. Review was under an existing IRB. Probe placement was governed by lesion size and prescribed by the ablation device computer algorithm (Nanoknife, AngioDynamics). Expected ablation size was calculated based on interprobe distance. All patients underwent CT with IV contrast on POD #1 or 2. Pre-ablation lesion sizes and post-procedure ablation zones were measured in three dimensions and volumes calculated using the formula for an ellipse. Ablation zones were also characterized qualitatively. Results: After the review, 2 tumors were discarded. Mean calculated ablation zone size was 24.7 cm 3, and mean volumes of hypodense and surrounding hyperemic ablation zones on early postoperative CT were 26.1 cm 3 and 42.1 cm 3, respectively. On late postablation imaging, mean volumes were 11.9 cm 3 and 15.2 cm 3, respectively. Three distinct post-ablation contrast enhancement patterns were observed, and one distinct pattern was associated with failure of ablation. Conclusion: In our retrospective series, we have observed an apparent ablation zone on early post-ablation imaging that can be variable in appearance. When hypodense and hyperemic zones are taken together, these ablation zones are larger than the ablation zones predicted by the device computer algorithm. This observation contradicts the nearly 1:1 correlation of imaging:histology ablation zone sizes observed in animal studies. It appears that the qualitative appearance of ablation zones on early post-operative imaging may predict success.
JVIR 䡲 Poster Sessions
S143
Ablation Zone Predicted and Actual
Lesion Size
Lesion Type
Calculated Ablation Zone Volume
1.4 x 1.0 x 1.3 cm 2.4 x 1.3 x 3.0 cm
Rectal Metastasis Colon Metastasis
28.7 cm 3 58.9 cm 3
1600 V/cm 1600 V/cm
1 1
17.0 cm 3 / 25.8 cm 3 20.9 cm 3 / 38.9 cm 3
2.0 x 0.8 x 0.5 cm 1.2 x 1.3 x 0.6 cm
HCC HCC
4.8 cm 3 5.6 cm 3
1824 V/cm 1972 V/cm
1 1
13.3 cm 3 / 0 10.3 cm 3 / 0
2.1 x 1.8 x 2.3 cm
Colon Metastasis
15.0 cm 3
1900 V/cm
1
2.1 x 2.2 x 1.7 cm
Colon Metastasis
35.0 cm 3
2000 V/cm
2
Power Delivered
Time to CT 1 (Days)
Ablation Zone Size Hypo/Hyper
Time to CT 2 (Days)
Ablation Zone Size Hypo/Hyper
9 6
23.7 cm 3 / 0 21.6 cm 3 / 33.2 cm 3 0.3 cm 3/ 0 1.5 cm 3 / 4.1 cm 3 3.7 cm 3 / 9.7 cm 3 20.7 cm 3 / 0
Abstract No. 356 Subxyphoid liver biopsy risk of pericardial tamponade: a CT anatomic study R.S. Florek1, F. Kushner2; 1Radiology, Lourdes Regional Medical Center, Lafayette, LA; 2Cardiology, West Jefferson Medical Center, Marrero, LA Purpose: Subxyphoid liver biopsy entails the risk of pericardial injury and tamponade. A review of 1127 therapeutic pericardiocenteses shows the risk of pericardial tamponade is increasing with the increasing number of thoracic interventions (1, 2). Pericardiocentesis can be performed if this complication is recognized (3). A PIAA review (4) of eleven cases of subxyphoid liver biopsy induced tamponade found one successful recognition and emergent pericardiocentesis, the patient survived and is doing well 3 yrs. later. The other 10 died. Awareness of this complication risk should increase the successful salvage rate. Materials and Methods: The level of the pericardium (PC) relative to the xyphoid tip was assessed in 100 sequential CT scans. Midline sagittal images were used to measure the location of the pericardium (PC) in the supine (biopsy) position to the lower tip of the xyphoid. CT scans were scored into 3 groups: Group A pc ⬎2cm above tip of the xyphoid; Group B 0 –2cm above; and Group C below the xyphoid. Results: Of the CT scans reviewed, 68% showed the pc to be greater than 2cm above the xyphoid tip; 20% were 0 –2 cm above the xyphoid tip; and in 12% the heart was below the tip of the xyphoid, indicating greatest risk of pericardial perforation. Conclusion: The risk of pericardial perforation during a subxyphoid liver biopsy increases with lower position of the heart. Assessment of the subxyphoid access window will be helpful in planning risk of the subxyphoid liver biopsy. References
Educational Exhibit
Abstract No. 357
Effective targeting of hepatic dome lesions during CT guided ablation procedures
88.4 cm 3 / 0
26 33
G.A. Franco, R.S. Williams, D.D. Kies, T.M. Fahrbach, J.F. Hart, J. Martin, M.K. Ford, H.S. Kim; Interventional Radiology, Emory Healthcare, Atlanta, GA Learning Objectives: To illustrate with the aid of diagrams and cross sectional imaging, a fast and effective approach to probe placement by using the “safe plane approach” method to historically difficult hepatic dome lesions. Background: Ablative technologies have advanced significantly over the past 2 decades. While there are many imaging modalities, CT and US remain the most commonly used. CT has numerous advantages over US. However, certain lesions remain difficult to target by CT. One such lesion is the hepatic dome lesion. Historically, hepatic dome lesions were accessed via a transthoracic approach, with ultrasound assistance or worse, deemed nonablatable. At our institution, we have implemented a fast and effective method to accurately place ablation probes within these difficult to treat hepatic dome lesion. Clinical Findings/Procedure Details: Initial evaluation: Review prior cross sectional imaging assessing lesion proximity to adjacent structures including vessel, Gleason’s capsule and the diaphragm. Evaluate for ascites and understand the background liver parenchyma. Procedure: The patient is placed supine/head first on the gantry and an initial CT is obtained through the liver with cutaneous markers in quiet respiration. The hepatic dome lesion is localized in the axial plane and 25 g needle is placed in the anterior abdominal wall corresponding to the axial and sagittal coordinates. A second needle is placed in the lateral abdominal wall corresponding to the coronal plane at the ablation probe skin entry site (usually 9th through 11th ribs). Skin entry site is chosen based on the safest/most effective probe course. The skin to lesion distance is measured and the ablation probe is advanced in the direction of the anterior abdominal needle from the skin entry site always being held parallel to the floor. This procedure limits the amount of repeat imaging saving time and radiation. A limited CT or CT fluoroscopy is used to make subtle adjustments in probe position. Once the probe is well position, the ablation is performed. Conclusion and/or Teaching Points: Effective CT guided ablation of historically difficult hepatic dome lesions can be achieved using the “safe plane approach”.
Abstract No. 358 Safety and tolerability of two dosing regimens of sorafenib in combination with locoregional therapy in patients with hepatocellular carcinoma
Poster Sessions
1. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical outcomes spanning 21 years. Tsang TS, Enriquez-Sarano M. Mayo Clin Proc. 2002 May;77(5):429-36. 2. Iatrogenic pericardial effusion and tamponade in the percutaneous intracardiac intervention era. Holmes DR, Nishimura R. JACC Cardiovasc Interv. 2009 Aug:2(8):705-17. 3. Rescue echocardiographically guided pericardiocentesis for cardiac perforation complicating catheter-based procedures. The Mayo Clinic Experience. Tsang TS, Freeman WK. J Am Coll Cardiol. 1998 Nov;32(5): 1345-50. 4. PIAA: Physicians Insurance Association of America: 2009 Review. United States. Pericardial tamponade from subxyphoid liver biopsy.
6.6 cm 3 / 76.2 cm 3
69 69