Imaging post liver thermal ablation: what you need to know

Transcription

1 Imaging post liver thermal ablation: what you need to know Poster No.: C-1376 Congress: ECR 2013 Type: Educational Exhibit Authors: D. K. Filippiadis, M. Mademli, A. Mazioti, N. Oikonomopoulos, S. Argentos, A. D. Kelekis, N. L. Kelekis; Athens/GR Keywords: Neoplasia, Metastases, Cancer, Imaging sequences, Contrast agent-intravenous, Ablation procedures, MR-Functional imaging, MR, CT, Liver, Interventional non-vascular, Abdomen DOI: /ecr2013/C-1376 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 22

2 Learning objectives To describe state-of-the art imaging post liver thermal ablation and response criteria, To analyze optimal imaging timing in relation to therapeutic and follow-up strategies, To illustrate future imaging potential and developments Page 2 of 22

3 Fig. 1 References: 2nd Radiology Dpt, University General Hospital "ATTIKON" Page 3 of 22

4 Images for this section: Fig. 1 Page 4 of 22

5 Background Hepatocellular carcinoma is the sixth most common cancer type and the third most common cause of cancer-related death. Hepatic metastases are the most common liver tumors; liver is the most common site of metastasis, second only to lymph nodes. Due to the hepatic anatomy and perfusion, metastasis can originate from any primary tumor; however most common sites of origin include colon, breast, lung and pancreas. Image-guided tumor ablation provides curative treatment in properly selected patients or appropriate therapeutic options whenever surgical techniques are precluded. Whenever liver is concerned the two most common thermal ablation techniques used are radiofrequency (RFA) and microwave (MWA) ablation. During MWA, tissues are heated faster than with radiofrequencies due to the more efficient transfer of heat. In contrast to radiofrequencies the circulation of which is hindered by high tissue impedance, microwaves can penetrate and thus heat any kind of tissue. Furthermore, microwaves are confined close to the antenna as opposed to radiofrequency which during ablation flows through the body to reach the grounding pads. Microwaves are governed by higher heating efficiency than radiofrequency which renders them unaffected by "heat sink" effect and blood vessels resulting in larger ablation volumes achieved in less time. Page 5 of 22

6 Fig. 2: CT-guided RFA of HCC. Both foci were ablated by means of an umbrellashaped radiofrequency electrode in the same session. References: 2nd Radiology Dpt, University General Hospital "ATTIKON" Page 6 of 22

7 Fig. 3: CT-guided MWA of two metastatic foci in the liver from bronchogenic carcinoma. MPR images (both parallel and perpendicular to the needle axis) provide valuable information upon penetration depth, exact position of the antenna in relation to the target and its margins and to essential close by anatomic structures. References: 2nd Radiology Dpt, University General Hospital "ATTIKON" Tumor response assessment post ablation is important in determining treatment success and future therapy. Initially, tumor response was assessed on the basis of the World Health Organization (WHO) criteria and the Response Evaluation Criteria in Solid Tumors (RECIST). Both WHO and RECIST criteria appreciate tumor response on the basis of determining changes in tumor and its anatomic size therefore they address tumor response on the basis of tumor shrinkage. Recently mrecist criteria were proposed for which image acquisition protocols optimization and consistency in the same protocol throughout follow-up examinations are requisites. Similarly to RECIST assessment of overall response with mrecist includes evaluation of the response of both target and nontarget lesions as well as potential new lesions. However, concerning the assessment of target lesion's response, mrecist appreciate apart from size reduction, the intratumoral arterial enhancement as viable tumor tissue. Images for this section: Page 7 of 22

8 Fig. 2: CT-guided RFA of HCC. Both foci were ablated by means of an umbrella-shaped radiofrequency electrode in the same session. Page 8 of 22

9 Fig. 3: CT-guided MWA of two metastatic foci in the liver from bronchogenic carcinoma. MPR images (both parallel and perpendicular to the needle axis) provide valuable information upon penetration depth, exact position of the antenna in relation to the target and its margins and to essential close by anatomic structures. Page 9 of 22

10 Imaging findings OR Procedure details Immediately post ablation session, a Computed Tomography scan including (noncontrast, arterial and portal phase) of the upper abdomen (from lung base to right kidney level) should be performed in order to identify (and possibly treat) any potential complications (eg pneumothorax, hemorrhage etc.) After patient's discharge from the hospital a common follow-up strategy for assessment of tumor response includes contrast enhanced multiphasic (non-contrast, arterial, portal, delayed phases) imaging with Computed Tomography or Magnetic Resonance at 1st and then every 3 months post ablation session. Total ablation of a hepatic lesion appears in CT as a homogeneous non-enhancing attenuation at the site of the ablated volume. Usually gas can be seen in the immediate post-session scan which in most cases resolves until the 1 month follow-up scan. Evidence of tumor remnants or recurrence include residual or new areas of contrast enhancement either marginal or internally to the ablation zone. KEEP IN MIND: Fibrous tissue due to scarring enhances with a slow and persistent mode throughout arterial, portal and delayed phase as opposed to tumor remnants or recurences which illustrate arterial enhancement and portal/delayed wash-out. Page 10 of 22

11 Fig. 4: Upper row: noncontrast (1A), arterial (1B) and portal (1C)phase of enhancement immediate post microwave ablation of a metastatic hepatic lesion (colon adenocarcinoma). Lower row (same patient): noncontrast (2A), arterial (2B) and portal (2C)phase of enhancement 1 month post microwave ablation. Immediately post ablation there inner enhancement in the ablated zone. One month post ablation there is a significant decrease of the surrounding reactive inflammation and still there is no inner enhancement in the ablated zone. These findings constitute with successful outcome of the interventional procedure. References: 2nd Radiology Dpt, University General Hospital "ATTIKON" MRI (conventional T1WI, T2WI, dynamic contrast-enhanced imaging), for tumor response assessment post liver thermal ablation, is considered the most accurate method in early detection of residual/recurrent tumors. In MRI, total ablation of a hepatic lesion appears as an area of high signal intensity in T1-weighted sequences with homogeneous lack of Gadolinium enhancement. Residual or reccurent tumor is governed by imaging findings similar to the tumor appearance prior to the ablation. One disadvantage of MRI is its incapability to distinguish viable cells from reactive granulation tissue. KEEP IN MIND: Page 11 of 22

12 Functional imaging, including diffusion MR imaging and apparent diffusion coefficient (ADC) mapping, has the ability to provide unique insight about molecular water distribution within a tumor, and therefore indicate tumor viability degree at cellular level. Fig. 5: Metastatic lesion from bronchogenic carcinoma. MRI showing restricted diffusion on DWI and ADC map (1a,b) and early enhancement of the lesion in arterial phase of the dynamic study after subtraction (1c). Follow-up MRI one month after treatment with RadioFrequency Ablation(RFA): high signal in DWI corresponds to T2 "sign through" effect and not in restricted diffussion(2a,b). Also there is no enhancement of the lesion, with only faint linear perilesional enhancement due to post RF hyperemia in arterial phase of the dynamic study after subtraction (2c). These findings constitute with successful outcome of the interventional procedure. References: 2nd Radiology Dpt, University General Hospital "ATTIKON" Page 12 of 22

13 Fig. 6: Follow-up MRI of the same patient 17 months post RF ablation showing increased SI in T2WI (1a), restricted diffusion (1b,c), low SI in THRIVE(2a), early contrast enhancement in arterial phase (2b) and wash out in delayed enhancement phase(10min)(2c). These findings constitute with local recurrence. References: 2nd Radiology Dpt, University General Hospital "ATTIKON" Page 13 of 22

14 Fig. 7: HCC after MW ablation demonstrates residual tumor as high signal intensity lesion in T2WI(1a) low SI in THRIVE, early enhancement in arterial phase of the dynamic study after subtraction (1c) and wash out in delayed enhancement phase(1h) (1d). in contrast to the above findings the successfully ablated area shows high SI in THRIVE(1b) and no enhancement in arterial phase of the dynamic study after subtraction (1c). References: 2nd Radiology Dpt, University General Hospital "ATTIKON" Contrast-enhanced ultrasound (CEUS) can provide valuable information and assess tumor response faster and at lower cost than computed tomography or magnetic resonance imaging. KEEP IN MIND: One disadvantage is that CEUS cannot be used in order to examine the total liver parenchyma for disease progression as CT and MR imaging can. Page 14 of 22

15 Fig. 8: A: HCC post RFA. Contrast enhanced ultrasound one month post ablation session illustrates enhancement of the residual tumor at arterial (A) phase and washout at delayed (B) phase. On the other hand, the ablated tumor illustrates no contrast uptake in both arterial and delayed phase. References: K. Chatzimixail, Lecturer of Diagnostic Radiology, 2nd Radiology Dpt, University General Hospital Recently, fluorodeoxyglucose positron emission tomography - computed tomography (PET-CT) imaging is increasingly used for tumor response and therapy appreciation post ablation. Residual or recurrent tumor demonstrates significantly higher standardizied values of uptake than the ones of reactive inflammation at the ablation margin. PET-CT uses a functional agent for tumor assessment with potentially earlier detection of residual or recurrent tumor. KEEP IN MIND: False-negative results of PET-CT have been reported in lesions with a diameter < 1cm due to partial volume effects and in patients suffering from diabetes. False-positive results of PET-CT have been reported in patients suffering from hepatic abscess. Images for this section: Page 15 of 22

16 Fig. 4: Upper row: noncontrast (1A), arterial (1B) and portal (1C)phase of enhancement immediate post microwave ablation of a metastatic hepatic lesion (colon adenocarcinoma). Lower row (same patient): noncontrast (2A), arterial (2B) and portal (2C)phase of enhancement 1 month post microwave ablation. Immediately post ablation there inner enhancement in the ablated zone. One month post ablation there is a significant decrease of the surrounding reactive inflammation and still there is no inner enhancement in the ablated zone. These findings constitute with successful outcome of the interventional procedure. Page 16 of 22

17 Fig. 5: Metastatic lesion from bronchogenic carcinoma. MRI showing restricted diffusion on DWI and ADC map (1a,b) and early enhancement of the lesion in arterial phase of the dynamic study after subtraction (1c). Follow-up MRI one month after treatment with RadioFrequency Ablation(RFA): high signal in DWI corresponds to T2 "sign through" effect and not in restricted diffussion(2a,b). Also there is no enhancement of the lesion, with only faint linear perilesional enhancement due to post RF hyperemia in arterial phase of the dynamic study after subtraction (2c). These findings constitute with successful outcome of the interventional procedure. Page 17 of 22

18 Fig. 6: Follow-up MRI of the same patient 17 months post RF ablation showing increased SI in T2WI (1a), restricted diffusion (1b,c), low SI in THRIVE(2a), early contrast enhancement in arterial phase (2b) and wash out in delayed enhancement phase(10min) (2c). These findings constitute with local recurrence. Page 18 of 22

19 Fig. 7: HCC after MW ablation demonstrates residual tumor as high signal intensity lesion in T2WI(1a) low SI in THRIVE, early enhancement in arterial phase of the dynamic study after subtraction (1c) and wash out in delayed enhancement phase(1h)(1d). in contrast to the above findings the successfully ablated area shows high SI in THRIVE(1b) and no enhancement in arterial phase of the dynamic study after subtraction (1c). Page 19 of 22

20 Fig. 8: A: HCC post RFA. Contrast enhanced ultrasound one month post ablation session illustrates enhancement of the residual tumor at arterial (A) phase and wash-out at delayed (B) phase. On the other hand, the ablated tumor illustrates no contrast uptake in both arterial and delayed phase. Page 20 of 22

21 Conclusion Accurate interpretation of post-ablation imaging findings is crucial for therapeutic and follow-up strategies. Computed Tomography (CT) can be used for the immediate assessment of the ablation (including efficacy and potential complications) or whenever MRI is not available. Magnetic Resonance Imaging (MRI) plays the most important role in patients' follow-up post liver thermal ablation therapies. DW-MR imaging has proved its promising character for the noninvasive assessment of tumor response to thermal ablation and prediction of tumor response. Contrast Enhanced Ultrasound (CEUS) is a promising imaging modality for tumor response assessment and prediction but further studies are necessary. Furthermore, disease progression cannot be evaluated when CEUS is solely performed. Fluorodeoxyglucose positron emission tomography - computed tomography (PET-CT) imaging is increasingly used for tumor response and therapy appreciation post ablation with potentially earlier detection of residual or recurrent tumor. However, further studies are necessary in order to clarify limitations of the modality and avoid falsenegative or false-positive results. References Lencioni R, Llovet JM. Modified RECIST (mrecist) assessment for hepatocellular carcinoma. Semin Liver Dis. 2010; 30(1): Georgakopoulos A, Pianou N, Kelekis N, Chatziioannou S. Impact of 18FFDG PET/CT on therapeutic decisions in patients with colorectal cancer and liver metastases. Clin Imaging [Epub ahead of print]. Poulou LS, Ziakas PD, Ziogas DC, Doxani C, Xyla V, Vakrinos G, Voulgarelis M, Thanos L. FDG-PET for detecting local tumor recurrence of ablated liver metastases: a diagnostic meta-analysis. Biomarkers. 2012;17(6): Delumeau S, Lebigot J, Ridereau-Zins C, Bouvier A, Boursier J, Aubé C. Imaging features and evaluation of liver lesions after non-surgical therapy. J Radiol. 2011; 92(7-8): Page 21 of 22

22 Schima W, Ba-Ssalamah A, Kurtaran A, Schindl M, Gruenberger T. Posttreatment imaging of liver tumours. Cancer Imaging. 2007; 7 Spec No A:S Vilqrain V. Advancement in HCC imaging: diagnosis, staging and treatment efficacy assessments: hepatocellular carcinoma: imaging in assessing treatment efficacy. J Hepatobiliary Pancreat Sci ;17(4): Personal Information Nikolaos L. Kelekis Professor of Diagnostic and Interventional Radiology 2nd Radiology Dpt, University General Hospital "ATTIKON", Athens/GR kelnik@med.uoa.gr Dimitrios K. Filippiadis Interventional Radiologist - Consultant 2nd Radiology Dpt, University General Hospital "ATTIKON", Athens/GR dfilippiadis@yahoo.gr Maria Mademli Consultant of Radiology 2nd Radiology Dpt, University General Hospital "ATTIKON", Athens/GR mariamademli@yahoo.gr Page 22 of 22