Multimodality imaging following 90Y radioembolization: a comprehensive review and pictorial essay

A case-based approach to common embolization agents used in vascular interventional radiology

OBJECTIVE

The objective of this article is to familiarize the reader with the most commonly used embolic agents in interventional radiology and discuss an approach for selecting among the different embolic agents. This article reviews their properties and uses a case-based approach to explain how to select one.

CONCLUSION

A wide variety of embolic agents are available. Familiarity with the available embolic agents and selection of the most appropriate embolic agent is critical in interventional radiology to achieve optimum therapeutic response and avoid undesired, potentially disastrous complications such as nontarget embolization.

Update on the role of imaging in management of metastatic colorectal cancer

Evolution in the treatment of metastatic colorectal cancer (mCRC) has led to significant improvement in the survival of these patients. Surgery is useful in patients with resectable disease. Liver-directed therapies such as hepatic arterial infusion, transarterial radio- and chemoembolization, and percutaneous ablation are sometimes used by oncologists when the liver is the only site of metastatic disease. Unresectable mCRC is typically treated with systemic chemotherapy. First-line systemic chemotherapeutic regimens for mCRC are FOLFOX (combination of 5-fluorouracil/leucovorin [5-FU/LV] and oxaliplatin) and FOLFIRI (combination of 5-FU/LV and irinotecan) combined with molecular targeted drugs. Molecular targeted therapies that are effective in treating mCRC include antiangiogenic agents such as bevacizumab-an antibody against vascular endothelial growth factor-and antibodies directed against epidermal growth factor receptor (EGFR). EGFR-directed antibodies such as cetuximab and panitumumab have been shown to produce activity only in wild-type KRAS tumors. Imaging modalities such as multidetector computed tomography (CT), magnetic resonance imaging, and positron emission tomography/CT play a major role in the selection of appropriate treatment strategies. Assessment of treatment response in patients who undergo liver-directed and systemic therapy requires imaging at regular intervals. Recent studies have shown that alternative treatment response criteria may be more predictive of pathologic response in mCRC than conventional criteria such as Response Evaluation Criteria in Solid Tumors. Awareness of unusual response patterns, as well as of complications and toxicities, is helpful in guiding patient management.

SIR-Spheres yttrium-90 radioembolization for the treatment of unresectable liver cancers

Transarterial radioembolization with yttrium-90 resin microspheres (SIR-Spheres; Sirtex Medical Limited, Sydney, Australia) is a liver-directed therapy that is gaining recognition as a treatment option for liver-dominant primary and metastatic cancers. The incidence of complications is low and can be further reduced by patient selection and rigorous pretreatment assessment. Ideal candidates for radioembolization have preserved liver function without ascites or encephalopathy, Child-Pugh score <7 and limited lung shunting. Phase III randomized controlled trials (RCTs) against other liver-directed therapies are lacking for intermediate-stage hepatocellular carcinoma. However, preliminary data from a recent RCT has suggested that radioembolization has a similar time-to-progression and comparable toxicity to selective chemoembolization. Phase II/III RCTs are now ongoing to evaluate the combination of radioembolization with systemic therapies in advanced-stage hepatocellular carcinoma and metastatic liver-dominant colorectal cancer in order to expand the treatment opportunities for patients with cancers in the liver.

Radioembolization for colorectal cancer liver metastases: current role and future opportunities – the medical oncologist’s perspective

SUMMARY 

The liver is the most common and often the only site of metastatic disease in patients with metastatic colorectal cancer. For patients who do not have resectable disease, a number of liver-directed therapies are increasingly being used in routine clinical practice, including yttrium-90 radioembolization. The challenge for the medical oncologist is how best to integrate this promising new option into routine practice in the setting of ever-evolving standard systemic therapy options. Here we review the most recent data on the efficacy and safety of yttrium-90, considerations when selecting patients for treatment and we examine the potential impact of current clinical trials.

Postradiation changes in tissues: evaluation by imaging studies with emphasis on fluorodeoxyglucose-PET/computed tomography and correlation with histopathologic findings

Efforts have been made to minimize the damage to adjacent normal tissues during radiotherapy, primarily by shifting from the use of conventional radiotherapy to more advanced techniques. Reviewing the overall pattern on combined anatomic and functional imaging can enhance diagnostic accuracy. Several radiotracers can be used; [(18)F]fluorodeoxyglucose is the most common. Familiarity with the type and timing of previous radiation therapy, the spectrum of imaging findings after radiation injury, and the appropriate use of the different radiotracers can be crucial. This article summarizes postradiation histologic findings and multimodality imaging findings, with emphasis on PET/computed tomography.

Yttrium-90 radioembolization of liver tumors: what do the images tell us?

Transarterial radioembolization (TARE) with yttrium 90 microspheres is an increasingly popular therapy for both primary and secondary liver malignancies. TARE entails delivery of β-particle brachytherapy and embolization of the tumor vasculature. The consequent biological sequelae are distinct from those of other transarterial therapies for liver tumors, as reflected in the often baffling post-treatment imaging features. As the clinical use of TARE is increasing, more diverse post-treatment radiological findings are encountered with variable overlap among treatment response, residual disease, reactionary changes and complications. Thus, post-TARE image interpretation is challenging. This review provides a comprehensive description of the different findings seen in post-treatment scans, with the aim of facilitating appropriate radiological interpretation of post-TARE pathologic changes, notwithstanding their existing limitations.

Imaging appearance of treated hepatocellular carcinoma

Surgical resection and imaging guided treatments play a crucial role in the management of hepatocellular carcinoma (HCC). Although the primary end point of treatment of HCC is survival, radiological response could be a surrogate end point of survival, and has a key role in HCC decision-making process. However, radiological assessment of HCC treatment efficacy is often controversial. There are few doubts on the evaluation of surgical resection; in fact, all known tumor sites should be removed. However, an unenhancing partial linear peripheral halo, in most cases, surrounding a fluid collection reducing in size during follow-up is demonstrated in successfully resected tumor with bipolar radiofrequency electrosurgical device. Efficacy assessment of locoregional therapies is more controversial and differs between percutaneous ablation (e.g., radiofrequency ablation and percutaneous ethanol injection) and transarterial treatments (e.g., conventional transarterial chemoembolization, transarterial chemoembolization with drug eluting beads and radioembolization). Finally, a different approach should be used for new systemic agent that, though not reducing tumor mass, could have a benefit on survival by delaying tumor progression and death. The purpose of this brief article is to review HCC imaging appearance after treatment.

Unresectable hepatocellular carcinoma: MR imaging after intraarterial therapy. Part I. Identification and validation of volumetric functional response criteria

PURPOSE

To identify and validate the optimal thresholds for volumetric functional MR imaging response criteria to predict overall survival after intraarterial treatment (IAT) in patients with unresectable hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Institutional review board approval and waiver of informed consent were obtained. A total of 143 patients who had undergone MR imaging before and 3-4 weeks after the first cycle of IAT were included. MR imaging analysis of one representative HCC index lesion was performed with proprietary software after initial treatment. Subjects were randomly divided into training (n = 114 [79.7%]) and validation (n = 29 [20.3%]) data sets. Uni- and multivariate Cox models were used to determine the best cutoffs, as well as survival differences, between response groups in the validation data set.

RESULTS

Optimal cutoffs in the training data set were 23% increase in apparent diffusion coefficient (ADC) and 65% decrease in volumetric enhancement in the portal venous phase (VE). Subsequently, 25% increase in ADC and 65% decrease in VE were used to stratify patients in the validation data set. Comparison of ADC responders (n = 12 [58.6%]) with nonresponders (n = 17 [34.5%]) showed significant differences in survival (25th percentile survival, 11.2 vs 4.9 months, respectively; P = .008), as did VE responders (n = 9 [31.0%]) compared with nonresponders (n = 20 [69.0%]; 25th percentile survival, 11.5 vs 5.1 months, respectively; P = .01). Stratification of patients with a combination of the criteria resulted in significant differences in survival between patients with lesions that fulfilled both criteria (n = 6 [20.7%]; too few cases to determine 25th percentile), one criterion (n = 9 [31.0%]; 25th percentile survival, 6.0 months), and neither criterion (n = 14 [48.3%]; 25th percentile survival, 5.1 months; P = .01). The association between the two criteria and overall survival remained significant in a multivariate analysis that included age, sex, Barcelona Clinic for Liver Cancer stage, and number of follow-up treatments.

CONCLUSION

After IAT for unresectable HCC, patients can be stratified into significantly different survival categories based on responder versus nonresponder status according to MR imaging ADC and VE cutoffs.

Evaluation of cancer treatment in the abdomen: Trends and advances

Response evaluation in Oncology has relied primarily on change in tumor size. Inconsistent results in the prediction of clinical outcome when size based criteria are used and the increasing role of targeted and loco-regional therapies have led to the development of new methods of response evaluation that are unrelated to change in tumor size. The goals of this review are to expose briefly the size based criteria and to present the non-size based approaches that are currently applicable in the clinical setting. Other paths that are still being explored are not discussed in details.

Immunogenic cell death biomarkers HMGB1, RAGE, and DNAse indicate response to radioembolization therapy and prognosis in colorectal cancer patients

Radioembolization therapy (RE) is an efficient locoregional treatment for liver metastases from colorectal cancer. Serum biomarkers involved in immunogenic cell death are potentially valuable for early predicting therapy response and estimating prognosis. In a prospective observation study, blood samples were taken from 49 consecutive colorectal cancer patients with extensive hepatic metastases before, 24 and 48 hr after RE. Serum levels of high mobility group box 1 (HMGB1), receptor of glycation end products (RAGE) and activity of desoxyribonuclease were compared with response to therapy regularly determined radiologically 3 months after therapy and with overall survival. Serum levels of HMGB1 were increased already 24 hr after RE, while RAGE levels were decreased and DNAse remained unchanged. In radiological staging, 35 patients demonstrated disease progression while 14 patients had stable disease or remission. Serum HMGB1 levels 24 hr after RE were significantly higher in progressive than in nonprogressive patients while for RAGE and DNAse no difference was observed between the response groups. Concerning overall survival, high pretherapeutic (0 hr) and 24 hr levels of HMGB1 were associated with poor outcome. Multivariate analysis including HMGB1, tumor, liver and inflammation markers revealed HMGB1 and CRP as independent prognostic parameters. HMGB1 is a valuable serum biomarker for early estimation of therapy response and prognosis in colorectal cancer patients with liver metastases undergoing RE therapy.

Circulating tumor cells: personalized medicine in interventional oncology?

Innovative technologic advancements have expanded the ability of interventional radiologists to capture and visualize directly tumor cells that have intravasated into the circulation. The detection of these circulating tumor cells (CTCs) is revolutionizing the understanding of the pathogenesis of metastasis and is paving the way for exquisitely sensitive techniques to detect malignancy, monitor recurrence, and prognosticate outcomes. In this review, the prevailing theories on the pathobiology of metastasis and the tools that have been developed to investigate CTCs are summarized. The tremendous impact CTCs are likely to have in oncology is discussed, with particular emphasis on their relevance to interventional oncology.

Hepatic radioembolization complicated by abscess

Hepatic abscess is a rare complication of yttrium-90 radioembolization of hepatic tumors that most commonly occurs in patients with a history of biliary intervention. Patients usually present several weeks after therapy with pain, nausea, vomiting, and fever. Cross-sectional imaging is necessary in cases of suspected abscess to ensure prompt diagnosis and to help plan treatment, which involves antibiotics and percutaneous drainage.

Embolization of parasitized extrahepatic arteries to reestablish intrahepatic arterial supply to tumors before yttrium-90 radioembolization

PURPOSE

To perform embolization of parasitized extrahepatic arteries (EHAs) before radioembolization to reestablish intrahepatic arterial supply to large, peripheral tumors, and to evaluate the technical and clinical outcomes of this intervention.

MATERIALS AND METHODS

Among 201 patients retrospectively analyzed, embolization of 73 parasitized EHAs in 35 patients was performed. Most embolization procedures were performed during preparatory angiography using large particles and coils. Digital subtraction angiography (DSA), C-arm computed tomography (CT), and technetium-99m macroaggregated albumin ((99m)TcMAA) scintigraphy were used to evaluate the immediate perfusion via intrahepatic collateral channels of target tumor areas previously supplied by parasitized EHAs. Follow-up imaging of differential regional tumor response was used to evaluate microsphere distribution and clinical outcome.

RESULTS

After embolization, reestablishment of intrahepatic arterial supply was confirmed by both DSA and C-arm CT in 94% of territories and by scintigraphy in 96%. In 32% of patients, the differential response of treatment could not be evaluated because of uniform disease progression. However, symmetric regional tumor response in 94% of evaluable patients indicated successful delivery of microspheres to the territories previously supplied by parasitized EHAs.

CONCLUSIONS

Reestablishment of intrahepatic arterial inflow to hepatic tumors by embolization of parasitized EHAs is safe and effective and results in successful delivery of yttrium-90 microspheres to tumors previously perfused by parasitized EHAs.

Yttrium-90 radioembolization as salvage therapy for colorectal cancer with liver metastases

BACKGROUND

Few patients with metastatic colorectal cancer (mCRC) are candidates for resection of their hepatic disease. Yttrium-90 ((90)Y) radioembolization has promise in the treatment of unresectable mCRC. We conducted a retrospective study to assess the efficacy in patients with refractory mCRC who underwent (90)Y radioembolization.

MATERIALS AND METHODS

Patients with unresectable mCRC with liver metastases treated at The Ohio State University were included in this analysis. Demographic data, carcinoembryonic antigen (CEA) values, observed toxicities, and information on prior therapies were collected. Response was assessed by RECIST (Response Evaluation Criteria in Solid Tumors) 1.1 criteria. Overall survival (OS) and progression-free survival (PFS) were estimated by the Kaplan-Meier method.

RESULTS

Twenty-four patients (median age, 63 years) were included. Of the patients, 54% had extrahepatic disease; 67% had bilobar involvement. The patients had received a median of 3 prior therapies. No objective responses were observed. Five patients had a CEA response. Median PFS and OS were 3.9 months (95% CI, 2.4-4.8 months) and 8.9 months (95% CI, 4.2-16.7 months), respectively. Patients older than 65 years had improved PFS (4.6 vs. 2.4 months) and OS (14 vs. 5.5 months) vs. younger patients, likely due to receipt of (90)Y treatment earlier in their disease course. The presence of extrahepatic disease and the absence of CEA response appeared negatively predictive of efficacy. Toxicities were expected and manageable.

CONCLUSION

(90)Y radioembolization is active in select patients with refractory mCRC and with liver metastases, and is safe and well tolerated in the elderly. In patients with extensive extrahepatic disease, (90)Y should be used in combination with chemotherapy. CEA may be a predictor of efficacy.

Predictive and prognostic value of circulating nucleosomes and serum biomarkers in patients with metastasized colorectal cancer undergoing Selective Internal Radiation Therapy

Background

Selective Internal Radiation Therapy (SIRT) is a new and effective locoregional anticancer therapy for colorectal cancer patients with liver metastases. Markers for prediction of therapy response and prognosis are needed for the individual management of those patients undergoing SIRT.

Methods

Blood samples were prospectively and consecutively taken from 49 colorectal cancer patients with extensive hepatic metastases before, three, six, 24 and 48 h after SIRT to analyze the concentrations of nucleosomes and further laboratory parameters, and to compare them with the response to therapy regularly determined 3 months after therapy and with overall survival.

Results

Circulating nucleosomes, cytokeratin-19 fragments (CYFRA 21-1), carcinoembryonic antigen (CEA), C-reactive protein (CRP) and various liver markers increased already 24 h after SIRT. Pretherapeutical levels of CYFRA 21-1, CEA, cancer antigen 19-9 (CA 19-9), asparate-aminotransferase (AST) and lactate dehydrogenase (LDH) as well as 24 h values of nucleosomes were significantly higher in patients suffering from disease progression (N = 35) than in non-progressive patients (N = 14). Concerning overall survival, CEA, CA 19-9, CYFRA 21-1, CRP, LDH, AST, choline esterase (CHE), gamma-glutamyl-transferase, alkaline phosphatase, and amylase (all 0 h, 24 h) and nucleosomes (24 h) were found to be prognostic relevant markers in univariate analyses. In multivariate Cox-Regression analysis, the best prognostic model was obtained for the combination of CRP and AST. When 24 h values were additionally included, nucleosomes (24 h) further improved the existing model.

Conclusion

Panels of biochemical markers are helpful to stratify pretherapeutically colorectal cancer patients for SIR-therapy and to early estimate the response to SIR-therapy.

Arterially directed therapies for hepatocellular carcinoma

OBJECTIVE

Arterially directed therapies for hepatocellular carcinoma are used for patients who are not candidates for surgery or ablation and for those who need a bridge or down-staging to liver transplantation. These therapies seem to prolong the overall survival when compared with supportive care.

CONCLUSION

Chemoembolization, particle embolization, drug-eluting beads, and radioembolization have been used for locoregional control. This review discusses patient selection, techniques, safety, clinical outcomes, and imaging findings related to these therapies.

Assessment of the treatment response of HCC

Surgical hepatectomy or liver transplantation are considered as curative treatment modalities for hepatocellular carcinoma (HCC). However, many patients are not surgical candidates at the time of diagnosis. Great improvements in locoregional therapies including local ablative therapy [radiofrequency (RF) ablation or ethanol ablation] and transarterial techniques (transarterial embolization or transarterial radioembolization) have made possible local control of HCC. For unresectable HCC, a targeted therapy with sorafenib may improve survival. Unlike treatment of other oncologic tumor, the locoregional therapies are mainstay in the treatment of HCC. Therefore, the application of classical criteria such as the World Health Organization (WHO) guideline may not be suitable for accurate treatment response assessment of locoregional therapies or targeted therapy of HCC. An understanding of the imaging features of post-treatment imaging after various treatment modalities for HCC is crucial for treatment response assessment and for determining further therapy. In this article, we review the role of various imaging modalities in assessing treatment response of locoregional therapies and the targeted molecular therapy.

Response to treatment series: part 2, tumor response assessment--using new and conventional criteria

OBJECTIVE

Conventional anatomic imaging biomarkers, including World Health Organization (WHO) criteria and Response Evaluation Criteria in Solid Tumors (RECIST), although effective, have limitations. This article will discuss the conventional and newer morphologic imaging biomarkers for the assessment of tumor response to therapy.

CONCLUSION

Applying established methods of assessing tumor response to therapy allows consistency in image interpretation and facilitates communication with oncologists. Because of the new methods of treatment, assessment of necrosis and volumetric information will need to be incorporated into size-based criteria.

Toxicities after radioembolization with yttrium-90 SIR-spheres: incidence and contributing risk factors at a single center

PURPOSE

To report the incidence of liver function test (LFT) toxicities after radioembolization with yttrium-90 ((90)Y) SIR-Spheres and review potential risk factors.

MATERIALS AND METHODS

Patients receiving (90)Y for radioembolization of primary or metastatic liver tumors had follow-up LFTs 29-571 days after treatment. The incidence and duration of bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) toxicities were documented using common terminology criteria. Factors that were assessed included previous intra-arterial (IA) therapy, systemic chemotherapy, low tumor-to-normal liver tissue ratio at mapping angiography, vascular stasis, and higher prescribed (90)Y doses.

RESULTS

There were 81 patients who underwent 122 infusions and had follow-up LFTs. Of 122 infusions, 71 (58%) were associated with toxicity. One patient died with radiation-induced liver disease. Grade 3 or greater toxicities occurred in seven (7%) patients after nine procedures. The median durations of laboratory elevations for bilirubin, AST, and ALT were 29 days, 29 days, and 20 days. Toxicity developed after 51 (71%) of 72 infusions with previous IA therapy versus 20 (40%) of 50 infusions in treatment-naïve areas (P = .0006). Absence of previous systemic therapy was associated with greater risk of toxicity versus previous chemotherapy (47% vs 66%, P = .03). Other factors were not associated with increased toxicity.

CONCLUSIONS

Mild hepatotoxicity developed frequently after infusion of SIR-Spheres using the body surface area method, with normalization of LFTs in most patients. Grade 3 or greater toxicities were seen in < 10% of infusions. Toxicity was strongly associated with previous IA therapy.

MR imaging of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy typically associated with chronic liver disease and is a leading cause of mortality among these patients. Prognosis is improved when detected early. MRI is the best imaging examination for accurate diagnosis. Although arterial enhancement with delayed washout, increased T2-weighted signal intensity, delayed capsular enhancement, restricted diffusion, and tumor thrombus are typical features, not all lesions demonstrate these findings. The radiologist must be familiar with these typical imaging characteristics, and less common appearances and associated findings of HCC, and must be able to differentiate them from those of lesions that mimic HCC. Knowledge of therapeutic options and how those are related to imaging findings is imperative to assist clinicians in managing these patients.

Imaging in interventional oncology

Medical imaging in interventional oncology is used differently than in diagnostic radiology and prioritizes different imaging features. Whereas diagnostic imaging prioritizes the highest-quality imaging, interventional imaging prioritizes real-time imaging with lower radiation dose in addition to high-quality imaging. In general, medical imaging plays five key roles in image-guided therapy, and interventional oncology, in particular. These roles are (a) preprocedure planning, (b) intraprocedural targeting, (c) intraprocedural monitoring, (d) intraprocedural control, and (e) postprocedure assessment. Although many of these roles are still relatively basic in interventional oncology, as research and development in medical imaging focuses on interventional needs, it is likely that the role of medical imaging in intervention will become even more integral and more widely applied. In this review, the current status of medical imaging for intervention in oncology will be described and directions for future development will be examined.

Embolization of hepatic arterial branches to simplify hepatic blood flow before yttrium 90 radioembolization: a useful technique in the presence of challenging anatomy

PURPOSE

In the presence of variant hepatic arterial anatomy, obtaining whole-liver coverage with yttrium 90 (Y90) radioembolization may be challenging. The purpose of this study was to determine whether a technique whereby variant hepatic arterial branches are embolized and then Y90 is administered selectively into one remaining hepatic arterial branch results in whole-liver coverage and effective therapy. A retrospective comparison of treatment response was made between a group of patients who underwent this technique before Y90 administration and a group of patients who received standard Y90 administration as a single dose into the proper hepatic artery or in divided doses into the immediate hepatic artery branches. The rest of the workup and treatment were identical in both groups, including routine embolization of potential nonhepatic, nontarget vessels (e.g., the gastroduodenal artery).

METHODS

A total of 32 patients (mean age 56.9 years, range 39-77 years) treated with Y90 between June 2004 and March 2008 were analyzed. The primary malignancy was colorectal in 29, breast in 2, and cholangiocarcinoma in 1. Group 1 comprised 20 patients who had no alterations to their hepatic arterial supply. Group 2 comprised 12 cases who had undergone prior embolization of hepatic arterial branches before administration of Y90. The response to treatment was assessed by comparing standardized uptake value (SUV) on the pre- and postprocedure fludeoxyglucose positron emission tomographic studies of representative lesions within the right and left lobes of the liver.

RESULTS

In group 1, significant response (P < 0.001) was seen among right lobe lesions but not among left lobe lesions (P = 0.549). In group 2, there was a significant response among both right (P = 0.028) and left (P = 0.014) lobe lesions. No difference was found in the response of right lobe lesions (P = 0.726) between groups 1 and 2; a significantly greater response was found in group 2 compared to group 1 (P = 0.004) for left lobe lesions.

CONCLUSION

Selective Y90 radioembolization after manipulation of hepatic arterial blood supply leads to an even distribution within the entire liver. When variations in hepatic arterial anatomy exist, this technique allows effective whole-liver radioembolization therapy from a single selective arterial injection.

Imaging to optimize liver tumor ablation

Surgical resection remains the ideal treatment for hepatocellular carcinoma and metastasis to the liver. Many alternatives are available for treatment of nonsurgical candidates. Regardless of treatment, optimizing imaging in the pretreatment, treatment and post-treatment settings is critical in order to lower the rates of local tumor progression and maximize the effectiveness of treatment that may result in prolonged survival. This article summarizes some basic imaging techniques of primary and metastatic liver tumors with a focus on how to optimize their treatment with ablation.

Multi-centre phase II clinical trial of yttrium-90 resin microspheres alone in unresectable, chemotherapy refractory colorectal liver metastases

BACKGROUND

This multi-centre phase II clinical trial is the first prospective evaluation of radioembolisation of patients with colorectal liver metastases (mCRC) who failed previous oxaliplatin- and irinotecan-based systemic chemotherapy regimens.

METHODS

Eligible patients had adequate hepatic, haemopoietic and renal function, and an absence of major hepatic vascular anomalies and hepato-pulmonary shunting. Gastroduodenal and right gastric arteries were embolised before hepatic arterial administration of yttrium-90 resin microspheres (median activity, 1.7 GBq; range, 0.9-2.2).

RESULTS

Of 50 eligible patients, 38 (76%) had received > or =4 lines of chemotherapy. Most presented with synchronous disease (72%), >4 hepatic metastases (58%), 25-50% replacement of total liver volume (60%) and bilateral spread (70%). Early and intermediate (>48 h) WHO G1-2 adverse events (mostly fever and pain) were observed in 16 and 22% of patients respectively. Two died due to renal failure at 40 days or liver failure at 60 days respectively. By intention-to-treat analysis using Response Evaluation Criteria in Solid Tumours, 1 patient (2%) had a complete response, 11 (22%) partial response, 12 (24%) stable disease, 22 (44%) progressive disease; 4 (8%) were non-evaluable. Median overall survival was 12.6 months (95% CI, 7.0-18.3); 2-year survival was 19.6%.

CONCLUSION

Radioembolisation produced meaningful response and disease stabilisation in patients with advanced, unresectable and chemorefractory mCRC.

State of the art: radiolabeled microspheres treatment for liver malignancies

IMPORTANCE OF THE FIELD

Metastatic tumours of the liver are responsible for significant morbidity and mortality, and only a small percentage is resectable with curative intent. Hepatic artery radioembolization (RE) with yttrium-90 ((90)Y)-loaded microspheres is an alternative treatment for patients with unresectable primary or secondary liver tumours, especially in cases of metastatic colorectal cancer (mCRC) and hepatocellular carcinoma (HCC).

AREAS COVERED IN THIS REVIEW

Data from recent relevant clinical trials with (90)Y-RE are discussed, focusing on response rate assessments and treatment outcome.

WHAT THE READER WILL GAIN

Current data show that (90)Y-RE combined with radiosensitizing chemotherapy is a safe and efficient modality that extends the time to progression in liver mCRC and unresectable HCC, although no survival benefits have been demonstrated. The treatment response after (90)Y-RE seems to be better assessed using metabolic response assessments with serial fluorodeoxyglucose positron emission tomography (FDG-PET) in cases of FDG-avid tumours than with morphological criteria measured on computed tomography or magnetic resonance imaging (RECIST or WHO trials). Predictive models using multimodality imaging approaches (PET-SPECT-CT image fusion algorithms) have been proposed to better select patients for (90)Y-RE. The optimal routine role of radioembolization remains to be defined; the complexity and wide availability of available therapeutic alternatives confuses the role of a locoregional treatment in a generalized disease.

TAKE HOME MESSAGE

(90)Y-RE is a safe and efficient treatment modality in salvage therapy of colorectal cancer metastatic to the liver and in unresectable HCC. However, it has still to find its place as a first- or second-line treatment of mCRC in combination with or as an alternative to available biological agents. The role of (90)Y-RE in other solid tumour types metastatic to the liver is much more uncertain and investigations in clinical situations in which disease is strictly limited to the liver are required. Pretherapeutic work-up, initially developed to explore hepatic vasculature and to assess lung shunting, might be able to predict treatment outcome, allowing a better patient selection.

Does multidetector CT attenuation change in colon cancer liver metastases treated with 90Y help predict metabolic activity at FDG PET?

PURPOSE

To evaluate the correlation between change in attenuation and tumor metabolic activity assessed by using fluorodeoxyglucose (FDG) positron emission tomography (PET) in colon cancer liver metastases treated with yttrium 90 ((90)Y) radioembolization.

MATERIALS AND METHODS

This Health Insurance Portability and Accountability Act-compliant retrospective study was approved by the institutional review board; patient informed consent was waived. Unresectable chemorefractory colon cancer liver metastases treated with (90)Y radioembolization in 28 patients were evaluated at pre- and posttreatment multidetector computed tomographic (CT) and FDG PET scans. Maximum cross-sectional diameter, volume, and overall attenuation of target lesions were calculated. The percentage change (%Delta) in these parameters after treatment was calculated and correlated with the standardized uptake value (SUV) analysis at FDG PET. The accuracy of the radiologic parameters in helping predict response to treatment at FDG PET was assessed. Data were analyzed by using the Student t, Wilcoxon matched pair, Mann-Whitney, Spearman rank correlation, and chi(2) tests. The significance level was set at .05.

RESULTS

Seventy-four metastatic lesions in 10 women and 18 men (mean age, 61.5 years +/- 14.3 [standard deviation]) were evaluated. Mean follow-up interval for multidetector CT after treatment was 30 days. A significant reduction in maximum cross-sectional diameter, volume, and attenuation was observed from pre- to posttreatment multidetector CT (P < .05). The %Delta in attenuation had higher correlation with %Delta in SUV (r = 0.61) than diameter (r = 0.39) or volume (r = 0.49) and also predicted the metabolic activity at FDG PET with higher sensitivity (P < .001). By using a threshold level of a reduction in attenuation of 15% or greater, attenuation showed 84.2% sensitivity and 83.3% specificity in predicting response at FDG PET evaluation.

CONCLUSION

Changes in attenuation of colon cancer liver metastases treated with (90)Y radioembolization correlate highly with metabolic activity at FDG PET and may be useful as an early surrogate marker for assessing treatment response.

Radioembolisation using yttrium 90 (Y-90) in patients affected by unresectable hepatic metastases

PURPOSE

This study was done to evaluate the effectiveness of radioembolisation of liver metastases with yttrium 90 (Y-90) in patients with no response to chemotherapy.

MATERIALS AND METHODS

From February 2005 to January 2008, we treated 110 patients affected by liver metastatic disease from colorectal, breast, gastric, pancreatic, pulmonary, oesophageal and pharyngeal cancers and from cholangiocarcinoma and melanoma. We excluded patients with bilirubin level >1.8 mg/dl and pulmonary shunt >20% but not patients with minor extrahepatic metastases.

RESULTS

We obtained a complete /partial response in 45 patients, stable disease in 42 patients and progressive disease in 23 patients. In 90 cases, we obtained a decrease in specific tumour marker level. The technical success rate was 96%, and technical effectiveness estimated at 3 months after treatment was 83.6%. Side effects were grade 4 hepatic failure in one case, grade 2 gastritis in six cases and grade 2 cholecystitis in two cases. The median survival and progression-free survival calculated by Kaplan-Meier analysis were 323 days and 245 days, respectively.

CONCLUSIONS

According to our 3-year experience, Y-90 radioembolisation (SIR-spheres) is a feasible and safe method to treat liver metastases with an acceptable level of complications and a good response rate.

Radiologic findings following Y90 radioembolization for primary liver malignancies

A therapy gaining rapid clinical adoption involves radioembolization with the use of Yttrium-90 (90Y) microspheres. The 20-60 microm-sized microspheres are injected trans-arterially and flow to hepatic tumors given their preferential blood supply from the hepatic artery. Once they lodge in the arterioles, they impart a very intense local radiotherapeutic effect. Given the combined radiation and embolic effect, the imaging findings imparted by this mode of action differ significantly from other treatments. This work represents a comprehensive review of the imaging findings following radioembolization in patients with primary liver tumors. The report discusses imaging response, benign secondary effects, and complications. This should help educate the radiologist on imaging findings that should be expected following radioembolization and therefore aid in the proper image interpretation.