90Y microsphere treatment of unresectable liver metastases: changes in 18F-FDG uptake and tumour size on PET/CT

Radioembolization-Induced Changes in Hepatic [18F]FDG Metabolism in Non-Tumorous Liver Parenchyma

Background: [18F]FDG-PET/CT is increasingly used for response assessments after oncologic treatment. The known response criteria for [18F]FDG-PET/CT use healthy liver parenchyma as the reference standard. However, the [18F]FDG liver metabolism results may change as a result of the given therapy. The aim of this study was to assess changes in [18F]FDG liver metabolism after hepatic 90Y resin radioembolization. Methods: [18F]FDG-PET/CT scans prior to radioembolization and one and three months after radioembolization (consistent with the PERCIST comparability criteria), as well as 90Y-PET/CT scans, were analyzed using 3 cm VOIs. The FDG activity concentration and absorbed dose were measured. A linear mixed-effects logistic regression model and logistic mixed-effects model were used to assess the correlation between the FDG-activity concentration, absorbed dose, and biochemical changes. Results: The median SULVOI,liver at baseline was 1.8 (range = 1.2−2.8). The mean change in SULVOI,liver per month with an increase in time was 0.05 (95%CI 0.02−0.09) at p < 0.001. The median absorbed dose per VOI was 31.3 Gy (range = 0.1−82.3 Gy). The mean percent change in ΔSULVOI,liver for every Gy increase in the absorbed dose was −0.04 (95%CI −0.22−0.14) at p = 0.67. The SULblood and SULspleen results showed no increase. Conclusions: The [18F]FDG metabolism in the normal liver parenchyma is significantly but mildly increased after radioembolization, which can interfere with its use as a threshold for therapy response.

Liver metastases

Liver metastases are commonly detected in a range of malignancies including colorectal cancer (CRC), pancreatic cancer, melanoma, lung cancer and breast cancer, although CRC is the most common primary cancer that metastasizes to the liver. Interactions between tumour cells and the tumour microenvironment play an important part in the engraftment, survival and progression of the metastases. Various cells including liver sinusoidal endothelial cells, Kupffer cells, hepatic stellate cells, parenchymal hepatocytes, dendritic cells, resident natural killer cells as well as other immune cells such as monocytes, macrophages and neutrophils are implicated in promoting and sustaining metastases in the liver. Four key phases (microvascular, pre-angiogenic, angiogenic and growth phases) have been identified in the process of liver metastasis. Imaging modalities such as ultrasonography, CT, MRI and PET scans are typically used for the diagnosis of liver metastases. Surgical resection remains the main potentially curative treatment among patients with resectable liver metastases. The role of liver transplantation in the management of liver metastasis remains controversial. Systemic therapies, newer biologic agents (for example, bevacizumab and cetuximab) and immunotherapeutic agents have revolutionized the treatment options for liver metastases. Moving forward, incorporation of genetic tests can provide more accurate information to guide clinical decision-making and predict prognosis among patients with liver metastases.

Prognostic value of ADC measurements in predicting overall survival in patients undergoing 90Y radioembolization for colorectal cancer liver metastases

AIM

To assess the ability of diffusion-weighted imaging (DWI) in predicting the overall survival in patients who underwent Yttrium 90 radioembolization (⁹⁰Y-RE) for colorectal liver metastases (CLM) with other well-established clinical and imaging parameters by comparing the pre- and post-treatment apparent diffusion coefficient (ADC) values of the lesions.

METHODS

A total of 81 metastatic lesions of 27 consecutive patients who underwent DWI before and after the ⁹⁰Y-RE session were enrolled in the study. ADC values were calculated from the entire (ADC_e) and peripheral (ADC_p) tumor on pre- and post-treatment DWI, and any relative increase in ADC >0% accepted as a functional imaging response. The impact of functional imaging response in addition to other well-known parameters including Response Evaluation Criteria in Solid Tumors (RECIST), hepatic tumor burden, Eastern Cooperative Oncology Group performance status (ECOG-PS) and the presence of extrahepatic metastases in predicting overall survival (OS) was assessed using Kaplan-Meier curves and Cox-regression analyses.

RESULTS

The median OS of the patients was 10 months (range, 6-20 months) while the median OS of the responders being significantly longer than the non-responders for ADC_e and ADC_p (median 11 vs 7 months, P = 0.003; median 12 vs. 7 months, P < 0.0001, respectively). The RECIST score was also significantly affected the OS (progressive or stable disease median 8 months vs. partial response 15 indent months, P = 0.019). The other parameters including hepatic tumor burden, gender, ECOG score, the involvement of the liver lobes, and the presence of extrahepatic metastases were not associated with the OS. In multivariate analysis, only ADC_p remained as an independent predictor of OS (P = 0.003, HR = 19.878).

CONCLUSION

Any increase in relative ADC_p or ADC_e values after Y90-RE treatment was associated with longer OS in CLM patients, and DWI seems to be valuable imaging biomarker in predicting OS in CLM patients during the early post-interventional period after ⁹⁰Y-RE.

Diffusion-weighted MRI Is Superior to PET/CT in Predicting Survival of Patients Undergoing 90Y Radioembolization of Hepatic Metastases

Purpose To determine the relationship between diffusion-weighted (DW) liver MR images obtained 4-6 weeks after lobar yttrium 90 (⁹⁰Y) treatment and overall survival in comparison with PET/CT or established oncologic factors known to affect survival. Materials and Methods The institutional review board approved this prospective intraindividual comparative study in 36 consecutive patients (25 women) with liver-dominant metastases (20 colorectal, 14 breast, two other) (mean age, 60 years ± 10 [standard deviation]) who underwent fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET/CT and DW MRI before and 4-6 weeks after ⁹⁰Y radioembolization. DW MRI response was defined as a mean minimal apparent diffusion coefficient increase of more than 30%; PET/CT response was defined as a mean maximal standardized uptake value decrease of more than 30%. Kaplan-Meier curves, log-rank test, and multivariable Cox regression analyses were used to compare patient survival as a function of imaging and Response Evaluation Criteria in Solid Tumors (RECIST) response, pretreatment Eastern Cooperative Oncology Group (ECOG) performance status (PS) (0 vs 1), hepatic tumor load (<25% vs ≥25%), and presence versus absence of extrahepatic disease. Results Thirty-five of the 36 patients were observed until death (median survival, 36 weeks). Response was observed with PET/CT in 18 of 36 patients (50%). Median survival was 39 weeks in patients who responded to PET/CT versus 27 weeks in those who did not (P = .60). Response was observed with DW MRI in 24 of 36 patients (67%). Median survival was 53 weeks in DW MRI responders versus 20 weeks in nonresponders (P = .01). At multivariable analysis, DW MRI response was the only independent predictor of survival (P < .01). Response based on RECIST parameters, ECOG PS, hepatic tumor load, and presence of extrahepatic metastases did not correlate with survival. Conclusion In patients with hepatic metastases undergoing ⁹⁰Y radioembolization, prediction of response to therapy with DW MRI was superior to that with PET/CT and established oncologic factors.

Predictors and prognosticators for survival with Yttrium-90 radioembolization therapy for unresectable colorectal cancer liver metastasis

This critical review aims to explore predictive and prognostic biomarkers of Yttrium-90 (Y90) radioembolization therapy of colorectal liver metastases. A brief overview of established predictive and prognostic molecular and genetic biomarkers in colorectal cancer therapies will be discussed. A review of the literature on imaging modalities, genetic, metabolic and other molecular markers and the subsequent outcomes in post-Y90 treatment will be presented. How these biomarkers and future biomarker research can inform locoregional treatment decisions in the clinical setting of metastatic colorectal cancer lesions of the liver will be explored. There are opportunities for personalized cancer treatment in the setting of Y90 radioembolization. The ability to predict tumor response after Ytrium-90 radioembolization therapy can greatly impact clinical decision making and enhance treatment outcomes, therefore further research into the field is needed.

Radiotherapy response evaluation using FDG PET-CT-established and emerging applications

Radiation therapy is a common component of curative cancer treatment. However, there is a significant incidence of treatment failure. In these cases, salvage surgical options are sometimes appropriate. Accurate assessment of response and early recognition of treatment success or failure is therefore critical to guide treatment decisions and impacts on survival and the morbidity of treatment. Traditionally, treatment response has depended upon the anatomical measurement of disease. However, this may not correlate well with the presence of disease, especially after radiotherapy. Combined positron emission tomography (PET) and CT imaging employs radioactive tracers to identify molecular characteristics of tissues. PET imaging exploits the fact that malignancies have characteristic molecular profiles which differ compared with surrounding tissues. The complementary anatomical and functional information facilitates accurate non-invasive assessment of surrogate biomarkers of disease activity.

The value of intravoxel incoherent motion model-based diffusion-weighted imaging for outcome prediction in resin-based radioembolization of breast cancer liver metastases

Purpose

To evaluate prognostic values of clinical and diffusion-weighted magnetic resonance imaging-derived intravoxel incoherent motion (IVIM) parameters in patients undergoing primary radioembolization for metastatic breast cancer liver metastases.

Subjects and methods

A total of 21 females (mean age 54 years, range 43–72 years) with liver-dominant metastatic breast cancer underwent standard liver magnetic resonance imaging (1.5 T, diffusion-weighted imaging with b-values of 0, 50, and 800 s/mm²) before and 4–6 weeks after radioembolization. The IVIM model-derived estimated diffusion coefficient D’ and the perfusion fraction f’ were evaluated by averaging the values of the two largest treated metastases in each patient. Kaplan–Meier and Cox regression analyses for overall survival (OS) were performed. Investigated parameters were changes in f’- and D’-values after therapy, age, sex, Eastern Cooperative Oncology Group (ECOG) status, grading of primary tumor, hepatic tumor burden, presence of extrahepatic disease, baseline bilirubin, previous bevacizumab therapy, early stasis during radioembolization, chemotherapy after radioembolization, repeated radioembolization and Response Evaluation Criteria in Solid Tumors (RECIST) response at 6-week follow-up.

Results

Median OS after radioembolization was 6 (range 1.5–54.9) months. In patients with therapy-induced decreasing or stable f’-values, median OS was significantly longer than in those with increased f’-values (7.6 [range 2.6–54.9] vs 2.6 [range 1.5–17.4] months, P<0.0001). Longer median OS was also seen in patients with increased D’-values (6 [range 1.6–54.9] vs 2.8 [range 1.5–17.4] months, P=0.008). Patients with remission or stable disease (responders) according to RECIST survived longer than nonresponders (7.2 [range 2.6–54.9] vs 2.6 [range 1.5–17.4] months, P<0.0001). An ECOG status ≤1 resulted in longer median OS than >1 (7.6 [range 2.6–54.9] vs 1.7 [range 1.5–4.5] months, P<0.0001). Pretreatment IVIM parameters and the other clinical characteristics were not associated with OS. Classification by f’-value changes and ECOG status remained as independent predictors of OS on multivariate analysis, while RECIST response and D’-value changes did not predict survival.

Conclusion

Following radioembolization of breast cancer liver metastases, early changes in the IVIM model-derived perfusion fraction f’ and baseline ECOG score were predictive of patient outcome, and may thus help to guide treatment strategy.

Evaluation of a Simplified Intravoxel Incoherent Motion (IVIM) Analysis of Diffusion-Weighted Imaging for Prediction of Tumor Size Changes and Imaging Response in Breast Cancer Liver Metastases Undergoing Radioembolization: A Retrospective Single Center Analysis

To investigate the value of a simplified intravoxel incoherent motion (IVIM) analysis for evaluation of therapy-induced tumor changes and response of breast cancer liver metastases (mBRC) undergoing radioembolization.In 21 females (mean age 54 years, range 43-72) with mBRC tumor size changes and response evaluation criteria in solid tumors (RECIST) response to 26 primary radioembolization procedures were analyzed. Standard 1.5-T liver magnetic resonance imaging including respiratory-gated diffusion-weighted imaging (DWI) with b0 = 0 s/mm, b1 = 50 s/mm, b2 = 800 s/mm before and 6 weeks after each treatment was performed. In addition to the apparent diffusion coefficient (ADC)(0,800), the estimated diffusion coefficient D' and the perfusion fraction f' were determined using a simplified IVIM approach. For each radioembolization, the 2 largest treated metastases (if available) were analyzed. Lesions were categorized according to size changes into group A (reduction of longest diameter [LD]) and group B (LD increase) after 3 months. Radioembolization procedures were further categorized into "response" (partial response and stable disease) and "nonresponse" (progressive disease) according to RECIST after 3 months. ADC and D' are given in 10 mm/s.Forty-five metastases were analyzed. Thirty-two lesions were categorized as A; 13 as B. Before therapy, group A lesions showed significantly larger f'-values than B (P = 0.001), but ADC(0,800) and D' did not differ. After therapy, in group A lesions the ADC(0,800)- and D'-values increased and f' decreased (P < 0.0001); in contrast in group B lesions f' increased (P = 0.001). Groups could be differentiated by preinterventional f' and by changes of D' and f' between pre and postinterventional imaging (area under the curve [AUC] of 0.903, 0.747 and 1.0, respectively).Preinterventional parameters did not differ between responders and nonresponders according to RECIST. ADC(0,800)- and D'-values showed a larger increase in responders compared with nonresponders (P = 0.013 and P = 0.001, respectively). After therapy f'-values decreased significantly in responders (P = 0.001). Good to excellent prediction of long-term RECIST response was possible by therapy-induced changes in LD, D', and f' (AUC 0.903, 0.879, and 0.867, respectively).A simplified IVIM model-based analysis of early post-treatment DWI can deliver additional information on tumor size changes and long-term RECIST response after radioembolization of mBRC. The estimated perfusion fraction f' is better suited for response assessment than the conventional ADC(0,800) or D'. This can be useful to guide further treatment strategy.

Diagnostic accuracy of diffusion-weighted magnetic resonance imaging versus positron emission tomography/computed tomography for early response assessment of liver metastases to Y90-radioembolization

Objectives

Patients with hepatic metastases who are candidates for Y90-radioembolization (Y90-RE) usually have advanced tumor stages with involvement of both liver lobes. Per current guidelines, these patients have usually undergone several cycles of potentially hepatotoxic systemic chemotherapy before Y90-RE is at all considered, requiring split (lobar) treatment sessions to reduce hepatic toxicity. Assessing response to Y90-RE early, that is, already after the first lobar session, would be helpful to avoid an ineffective and potentially hepatotoxic second lobar treatment. We investigated the accuracy with which diffusion- weighted magnetic resonance imaging (DWI-MRI) and positron emission tomography/computed tomography (PET/CT) can provide this information.

Methods

An institutional review board–approved prospective intraindividual comparison trial on 35 patients who underwent fluorodeoxyglucose PET/CT and DWI-MRI within 6 weeks before and 6 weeks after Y90-RE to treat secondary-progressive liver metastases from solid cancers (20 colorectal, 13 breast, 2 other) was performed. An increase of minimal apparent diffusion coefficient (ADCmin) or decrease of maximum standard uptake value (SUVmax) by at least 30% was regarded as positive response. Long-term clinical and imaging follow-up was used to distinguish true- from false-response classifications.

Results

On the basis of long-term follow-up, 23 (66%) of 35 patients responded to the Y90 treatment. No significant changes of metastases size or contrast enhancement were observable on pretreatment versus posttreatment CT or magnetic resonance images.However, overall SUVmax decreased from 8.0 ± 3.9 to 5.5 ± 2.2 (P < 0.0001), and ADCmin increased from 0.53 ± 0.13 × 10⁻³ mm²/s to 0.77 ± 0.26 × 10⁻³ mm²/s (P < 0.0001). Pretherapeutic versus posttherapeutic changes of ADCmin and SUVmax correlated moderately (r = −0.53). In 4 of the 35 patients (11%), metastases were fluorodeoxyglucose-negative such that no response assessment was possible by PET. In 25 (71%) of the 35 patients, response classification by PET and DWI-MRI was concordant; in 6 (17%) of the 35, it was discordant. In 5 of the 6 patients with discordant classifications, follow-up confirmed diagnoses made by DWI. The positive predictive value to predict response was 22 (96%) of 23 for MRI and 15 (88%) of 17 for PET. The negative predictive value to predict absence was 11 (92%) of 12 for MRI and 10 (56%) of 18 for PET. Sensitivity for detecting response was significantly higher for MRI (96%; 22/23) than for PET (65%; 15/23) (P < 0.02).

Conclusions

Diffusion-weighted magnetic resonance imaging appears superior to PET/CT for early response assessment in patients with hepatic metastases of common solid tumors. It may be used in between lobar treatment sessions to guide further management of patients who undergo Y90-RE for hepatic metastases.

A systematic review on the safety and effectiveness of yttrium-90 radioembolization for hepatocellular carcinoma with portal vein tumor thrombosis

BACKGROUND/AIM

Over the past two decades, several advances have been made in the management of patients with hepatocellular carcinoma (HCC) and portal vein tumor thrombosis (PVTT). Yttrium-90 ( 90 Y) radioembolization has recently been made a treatment option for patients with HCC and PVTT. However, there is still a need to systematicly evaluate the outcomes of 90 Y radioembolization for HCC and PVTT. We aimed to assess the safety and effectiveness of 90 Y radioembolization for HCC and PVTT. We performed a systematic review of clinical trials, clinical studies, and abstracts from conferences that qualified for analysis.

MATERIALS AND METHODS

PubMed, EMBASE, Cochrane Database of Systematic Review, CINAHL, and the "gray" literature (Google Scholar) were searched for all reports (1991-2016) related to 90 Y radioembolization for HCC and PVTT.

RESULTS

A total of 14 clinical studies and three abstracts from conferences including 722 patients qualified for the analysis. The median length of follow-up was 7.2 months; the median time to progression was 5.6 months, and median disease control rate was 74.3%. Radiological response data were reported in five studies, and the median reported value of patients with complete response, partial response, stable disease, and progressive disease were 3.2%, 16.5%, 31.3%, and 28%, respectively. The median survival was 9.7 months for all patients, including the median overall survival (OS) were 12.1, 6.1 months of Child-Pugh class A and B patients, and the median OS were 6.1, 13.4 months of main and branch PVTT patients, respectively. The common toxicities were fatigue, nausea/vomiting, abdominal pain, mostly not requiring medical intervention needed no medication intervention.

CONCLUSIONS

90 Y radioembolization is a safe and effective treatment for HCC and PVTT.

Y90 radioembolization of colorectal cancer liver metastases: response assessment by contrast-enhanced computed tomography with or without PET-CT guidance

PURPOSE

To compare various computed tomography (CT) parameters to the positron emission tomography with computed tomography (PET-CT) response, with or without PET guidance for the response assessment of colorectal cancer (CRC) metastases treated by Y90 radioembolization.

METHODS

Thirty-six CRC metastases were retrospectively evaluated on 18F-Fluoro-Deoxy-Glucose PET-CT and contrast-enhanced computed tomography (CECT) performed at baseline and 2-3 months after Y90 radioembolization.

RESULTS

Median SUVmax values decreased from 11.39 to 6.71 after radioembolization (P<.001), and 23/36 (64%) metastases were categorized metabolic responses according to European Organisation for Research and Treatment of Cancer criteria. Only a decrease of the mean attenuation in the structural (P<.001) and metabolic active volume (P<.001) was observed. The change in these criteria was correlated with the change of SUVmax.

Survival in patients with hepatocellular carcinoma treated with 90Y-microsphere radioembolization. Prediction by 18F-FDG PET

AIM

This retrospective study aims to evaluate the predictive value of FDG PET/CT in patients with unresectable hepatocellular carcinoma (HCC) undergoing radioembolization with yttrium-90 labeled microspheres (RE).

PATIENTS, METHODS

The study cohort comprised 33 patients who were treated with RE at our institution and underwent FDG PET/CT at baseline and four weeks after radioembolization. According to the baseline FDG metabolic status of the HCC lesions, patients were divided into two groups: FDG-negative (n = 12) and FDG-positive (n = 21) HCC. FDG-positive patients were further divided into early metabolic responders and non-responders according to the relative change in SUVmax of the treated lesions. Survival analyses were performed with the Kaplan-Meier method (log-rank test, p < 0.05). Multivariate analysis was performed to assess the influence of prognostic factors on overall survival (OS).

RESULTS

FDG-negative patients had a significantly longer OS (13 months, 95%CI 7-19) than FDG-positive patients (9 months, 95%CI 7-11; p = 0.010). Among FDG-positive patients, metabolic responders survived significantly longer than metabolic non-responders (10 months, 95%CI 8-12 vs. 5 months, 95%CI 4-6; p = 0.003). From the other baseline factors (including performance status, hepatic tumour burden, presence of extra-hepatic disease, administered activity) only the BCLC stage had a significant impact on OS (p = 0.028).

CONCLUSION

Pre- and post-therapeutic FDG PET independently predicts overall survival in patients with HCC undergoing radioembolization. Interestingly, early metabolic response seems to be assessable as early as four weeks post-treatment.

Imaging tumor response following liver-directed intra-arterial therapy

Liver-directed intra-arterial therapies are palliative treatment options for patients with unresectable liver cancer; their use has also resulted in patients being downstaged leading to curative resection and transplantation. These intra-arterial therapies include transarterial embolization, conventional transarterial chemoembolization (TACE), drug-eluting bead TACE and radioembolization. Assessment of imaging response following these liver-directed intra-arterial therapies is challenging but pivotal for patient management. Size measurements based on computed tomography or magnetic resonance imaging (MRI) have been traditionally used to assess tumor response to therapy. However, these anatomic changes lag behind functional changes and may require months to occur. Further, these intra-arterial therapies cause acute tumor necrosis, which may result in a paradoxical increase in tumor size on early follow-up imaging despite complete cell death or necrosis. This concept is unique comparing to changes seen following systemic chemotherapy. The recent development of functional imaging techniques including diffusion-weighted MRI (DW MRI) and positron emission tomography (PET) allow for early assessment of treatment response and even prediction of overall tumor response to intra-arterial therapies. Although the results of DW MRI and PET studies are promising, the impact of these imaging modalities to assess treatment response has been limited without standardized protocols. The aim of this review article is to delineate the best practice for assessing tumor response in patients with primary or secondary hepatic malignancies undergoing intra-arterial therapies.

Prognostic importance of 18F-FDG uptake pattern of hepatocellular cancer patients who received SIRT

PURPOSE

The aim of the study was to evaluate the effect of 18F-FDG uptake pattern of liver lesions to treatment response of patients who received yttrium-90 (Y-90) selective internal radiation therapy (SIRT) for hepatocellular cancer (HCC).

PATIENTS AND METHODS

Nineteen patients (5F, 14M, mean age: 64.5 ± 14.7 years old, range: 57-73 years) who received SIRT treatment in our department for HCC between June 2008 and May 2011 were included in the study. All patients underwent 18F-FDG PET/CT before SIRT for evaluation of disease stage and metabolic activity of liver lesions. Patients were divided into 3 groups according to FDG uptake patterns of primary liver lesions (hypoactive, nonhomogenous, and focal intense). Progression-free survival (PFS) times of each group and patients with hepatic only and hepatic with extrahepatic disease were analyzed. Disease progression criteria were increase in tumor volume, progressive elevation of serum alpha-fetoprotein levels, and detection of extrahepatic metastases. Kaplan-Meier analysis was used for comparison of PFS times.

RESULTS

The mean treatment dose was calculated as 1.4 ± 1.0 GBq. While liver lesions of 4 patients were hypoactive in pretreatment 18F-FDG PET/CT, liver lesions of 6 and 9 patients had nonhomogenous and intense FDG uptake, respectively. Mean PFS time of patients who had hypoactive liver lesions was 5.25 ± 1.52 months. In patients who had liver lesions with nonhomogenous uptake, mean PFS time was 12.3 ± 2.6 months. Lastly, in patients with intense uptake in liver lesions, PFS time was calculated as 19.8 ± 5.0 months. Difference between each group was statistically significant (P = 0.017). There was no significant difference in the PFS of the patients with limited hepatic disease and patients with extrahepatic involvement.

CONCLUSION

In patients with unresectable HCC, higher SUVmax lesions unexpectedly had better PFS rates after SIRT, suggesting SIRT has a treatment advantage over other therapeutic options in these patients.

Fractionated radioimmunotherapy with ⁹⁰Y-labeled fully human anti-CEA antibody

Carcinoembryonic antigen (CEA) is an attractive target molecule of radioimmunotherapy (RIT). To enhance RIT's therapeutic efficacy, the fractionation of radiolabeled antibody doses is an attractive strategy. In this study, a fully human anti-CEA monoclonal antibody (mAb) C2-45 was selected by virtue of its lack of immunogenicity, and the effectiveness of fractionated RIT with yttrium-90 (⁹⁰Y)-labeled mAb C2-45 was evaluated. In LS180 tumor-bearing mice, indium-111 (¹¹¹In)-labeled mAb C2-45 showed high and persistent tumor accumulation. Therapeutic studies were performed with single doses of ⁹⁰Y-mAb C2-45 (100 or 200 μCi) or double doses of 100 μCi ⁹⁰Y-mAb C2-45 at different intervals (5, 10, and 15 days). All ⁹⁰Y-mAb C2-45-treated mice showed inhibition of tumor progression, while the time to tumor progression was much longer in both the 200-μCi-treated group and the double 100-μCi-treated group than in the single 100-μCi-treated group. The therapeutic effect of the double 100 μCi administration at days 0 and 15 lasted significantly longer than that in the other treatment groups. These findings indicate that ⁹⁰Y-mAb C2-45 may be a promising agent for the treatment of CEA-positive cancer and that the fractionation of ⁹⁰Y-labeled antibody doses could enhance the therapeutic effect if performed according to an appropriate protocol.

Radioembolization as locoregional therapy of hepatic metastases in uveal melanoma patients

PURPOSE

To retrospectively evaluate the overall survival, safety, and efficacy of metastatic uveal melanoma patients after radioembolization as salvage therapy.

MATERIALS AND METHODS

Thirteen patients were treated with radioembolization of branches of the hepatic artery with resin-based yttrium-90 ((90)Y)-labelled microspheres. Twelve patients underwent a single application, and 1 patient underwent 4 interventions. Dosages from 644 to 2,450 MBq (mean activity 1,780) were applied. Treatment response was evaluated by way of liver magnetic resonance imaging and computed tomography (CT) as well as whole-body fluorodeoxyglucose positron emission tomography (PET)/CT with evaluation of percentage changes in SUV(max) before and at 2-3 months after therapy. Kaplan-Meier analysis was calculated to determine overall survival.

RESULTS

Partial remission (PR) was observed in 8 (62 %), stable disease (SD) in 2 (15 %), and progressive disease (PD) in 3 (23 %) patients under terms of standard criteria and PR in 3 (23 %), SD in 3 (23 %), and PD in 7 (54 %) patients according to PET criteria. Neither RECIST nor PET criteria showed a significant difference in predicting overall survival (P = 0.12 and 0.11, respectively). Median survival time after radioembolization was 7 months. No acute toxicity with in-hospital morbidity was observed. One patient developed hepatomegaly, and 1 patient developed gastric ulceration. Throughout follow-up, progression of extrahepatic metastases was observed.

CONCLUSION

Radioembolization may be a promising therapy in uveal melanoma patients with predominant hepatic metastases. At first follow-up, we observed PR or SD in 77 % patients under terms of standard criteria with an acceptable toxicity profile.

18F-FDG PET/CT predicts survival after radioembolization of hepatic metastases from breast cancer

(90)Y radioembolization (selective internal radiation therapy [SIRT]) has emerged as a valuable therapeutic option in unresectable, chemotherapy-refractory hepatic metastases from breast cancer. The objective of the present study was to evaluate (18)F-FDG PET/CT for predicting survival in these patients.

METHODS

Fifty-eight consecutive patients with hepatic metastases from breast cancer were treated with SIRT. Before therapy, all patients underwent MRI of the liver. (18)F-FDG PET/CT was performed at baseline and 3 mo after SIRT to calculate percentage changes in maximum (18)F-FDG standardized uptake value (SUV(max)) relative to baseline. A decrease of more than 30% in the follow-up scan, compared with the baseline examination, indicated therapy response. Treatment response at 3 mo was also assessed in 43 patients using contrast-enhanced MRI and CT on the basis of the Response Evaluation Criteria in Solid Tumors. All patients were followed to complete survival data.

RESULTS

Overall median survival after SIRT was 47 wk. Response as assessed with SUV(max) correlated significantly with survival after radioembolization, with responders having significantly longer survival (65 wk) than nonresponders (43 wk; P < 0.05). In multivariate analysis the change in SUV(max) was identified as the only independent predictor of survival (hazard ratio, 0.23; P < 0.005). Furthermore, a high pretherapeutic SUV(max) (>20) was associated with a significantly shorter median survival than was an SUV(max) of 20 or less (21 vs. 52 wk; P < 0.005). The presence of extrahepatic metastases (mean survival in both groups, 47 wk; P = 0.92), hormone receptor status (estrogen, P = 0.53; progesterone, P = 0.79; Her-2/neu, P = 0.49), and MRI/CT response (P = 0.91) did not predict survival.

CONCLUSION

The change in SUV(max) as assessed by (18)F-FDG PET/CT before and 3 mo after SIRT was identified as the only independent predictor of survival in patients with hepatic metastases of breast cancer.

Selective intraarterial radionuclide therapy with Yttrium-90 (Y-90) microspheres for unresectable primary and metastatic liver tumors

Background

The aim of this study was to evaluate the success of selective intraarterial radionuclide therapy (SIRT) with Yttrium-90 (Y-90) microspheres in liver metastases of different tumors. We also interpreted the contribution of SIRT to survival times according to responder- non responder and hepatic- extra hepatic disease.

Methods

The clinical and follow-up data of 124 patients who were referred to our department for SIRT between June 2006 and October 2010 were evaluated retrospectively. SIRT has been applied to 78 patients who were suitable for treatment. All the patients had primary liver tumor or unresectable liver metastasis of different malignancies. The treatment was repeated at least one more time in 5 patients to the same or other lobes. Metabolic treatment response evaluated by fluorine-18 fluorodeoxyglucose (F18-FDG) positron emission tomography/computed tomography (PET/CT) in the 6^th week after treatment. F18-FDG PET/CT was repeated in per six weeks periods. The response criterion had been described as at least 20% decrease of SUV value. Also in patients with neuroendocrine tumor serial Gallium-68 (Ga-68) PET/CT was used for evaluation of response. Patients were divided into 2 groups according to their treatment response.

Results

68 patients received treatment for the right lobe, seven patients received treatment for the left lobe and 3 patients for both lobes. The mean treatment dose was estimated at 1.62 GBq. In the evaluation of treatment response; 43(55%) patients were responder (R) and 35 (45%) patients were non-responder (NR) in the sixth week F18-FDG PET/CT. Mean pretreatment SUVmax value of R group was 11.6 and NR group was 10.7. While only 11 (31%) out of 35 NR patients had H disease, 30 (69%) out of 43 R patients had H disease (p < 0.05). The mean overall survival time of R group was calculated as 25.63 ± 1.52 months and NR group's 20.45 ± 2.11 (p = 0.04). The mean overall survival time of H group was computed as 25.66 ± 1.52 months and EH group's 20.76 ± 1.97 (p = 0.09).

Conclusions

SIRT is a useful treatment method which can contribute to the lengthening of survival times in patients with primary or metastatic unresectable liver malignancies. Also F18-FDG PET/CT is seen to be a successful imaging method in evaluating treatment response for predicting survival times in this patient group.

Positron emission tomography and colorectal cancer

Colorectal cancer (CRC) is a major cause of cancer-related morbidity and mortality. Molecular imaging using positron emission tomography (PET) is now an integral part of multidisciplinary cancer care. In this review, we discuss the role of PET in CRC including well established indications in the assessment of recurrent disease and emerging applications such as initial staging, monitoring therapy efficacy and using PET for radiotherapy planning. With rapid advancement in imaging technology, we also discuss the future potential of combining PET and magnetic resonance imaging and the use of novel radiotracers.

Radioembolization of liver tumors with yttrium-90 microspheres

Radioembolization (RE), also termed selective internal radiation therapy (SIRT), has been gradually introduced to the clinical arsenal of cytoreductive modalities in recent years. There is growing evidence for efficiency in liver tumors of various entities, with the most prominent ones being hepatocellular carcinoma, colorectal cancer, and neuroendocrine tumors. Hepatic metastases of numerous other tumor entities including breast cancer, cholangiocarcinoma, and pancreatic cancer are treatment-sensitive, even when being refractory to other treatment modalities such as bland-embolization, regional, or systemic chemotherapy. The antitumor effect of SIRT is related to radiation rather than embolization, with extraordinary high local radiation doses obtained selectively at the site of viable tumor and little affection of the surrounding normal liver tissue. Morphologic changes after RE may pose difficulties for interpretation in conventional restaging with regard to tumor viability and true response to treatment. Therefore, functional imaging, that is, metabolic imaging with (18)F fluorodeoxyglucose positron emission tomography (computed tomography) in the majority of treated tumors, is regarded the gold standard in this respect and should be included for pre- and post-SIRT assessment. To prevent serious toxicity to be associated with the potent antitumor efficacy, meticulous pretreatment evaluation is of particular importance. Improvements in predicting dosimetry will help optimize treatment and patient selection. Nuclear medicine procedures are essential for planning, performing, and monitoring of RE. However, the interdisciplinary aspect of patient management has to be emphasized for this particular treatment form. As SIRT is moving forward from the salvage setting indication to the use in earlier stages of hepatic tumor disease and with the advent of new treatment protocols and targeted therapies, embedding SIRT into a multidisciplinary approach will become even more important. This article focuses on procedural and technical aspects for selection, preparation, and performance of treatment as well as post-therapeutic monitoring and response assessment.

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.

Direct in vivo injection of 131I-GMS and its distribution and excretion in rabbit

AIM: To explore the distribution and metabolism of ¹³¹I-gelatin microspheres (¹³¹I-GMSs) in rabbits after direct injection into rabbits’ livers.

METHODS: Twenty-eight healthy New Zealand rabbits were divided into seven groups, with four rabbits per group. Each rabbit’s hepatic lobes were directly injected with 41.336 ± 5.106 MBq ¹³¹I-GMSs. Each day after ¹³¹I-GMSs administration, 4 rabbits were randomly selected, and 250 μL of serum was collected for γ count. Hepatic and thyroid functions were tested on days 1, 4, 8, 16, 24, 32, 48 and 64 after ¹³¹I-GMSs administration. Single-photon emission computed tomography (SPECT) was taken for each group on days 0, 1, 4, 8, 16, 24, 32, 48, 64 after ¹³¹I-GMSs administration. A group of rabbits were sacrificed respectively on days 1, 4, 16, 24, 32, 48, 64 after ¹³¹I-GMSs administration. Their livers were taken out for histological examination.

RESULTS: After ¹³¹I-GMSs administration, the nuclide was collected in the hepatic area with microspheres. The radiation could be detected on day 48 after ¹³¹I-GMSs administration, and radiography could be seen in thyroid areas in SPECT on days 4, 8, 16 and 24. One day after ¹³¹I-GMSs administration, the liver function was damaged but recovered 4 d later. Eight days after ¹³¹I-GMSs administration, the levels of free triiodothyronine and free thyroxin were reduced, which restored to normal levels on day 16. Histological examination showed that the microspheres were degraded to different degrees at 24, 32 and 48 d after ¹³¹I-GMSs administration. The surrounding parts of injection points were in fibrous sheathing. No microspheres were detected in histological examination on day 64 after ¹³¹I-GMSs administration.

CONCLUSION: Direct in vivo injection of ¹³¹I-GMSs is safe in rabbits. It may be a promising method for treatment of malignant tumors.

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.

Selective internal radiation therapy with SIR-spheres for the treatment of unresectable colorectal hepatic metastases

The purpose of this study was to evaluate the effectiveness of colorectal cancer (CRC) liver metastasis radioembolization with yttrium-90 (Y90), assessing toxicity and survival rates in patients with no response to chemotherapy through our 3-year experience. From February 2005 to January 2008, we treated 41 patients affected by CRC from a cohort of selective internal radiation therapy patients treated at our institution. All patients examined showed disease progression and arrived for our observation with an abdominal CT, a body PET, and a hepatic angiography followed by gastroduodenal artery coiling previously performed by us. We excluded patients with a bilirubin level>1.8 mg/dl and pulmonary shunt>20% but not patients with minor extrahepatic metastases. On treatment day, under fluoroscopic guidance, we implanted a dose of Y90 microspheres calculated on the basis of liver tumoral involvement and the body surface area formula. All patients were discharged the day after treatment. We obtained, according to Response Evaluation Criteria on Solid Tumors, a complete response in 2 patients, a partial response in 17 patients, stable disease in 14 patients, and progressive disease in 8 patients. In all cases, we obtained a carcinoembryonic antigen level decrease, especially in the week 8 evaluation. Technical success rate was 98% and technical effectiveness estimated at 3 months after treatment was 80.5%. Side effects graded by Common Terminology Criteria on Adverse Events were represented by one grade 4 hepatic failure, two grade 2 gastritis, and one grade 2 cholecystitis. The median survival and the progression-free survival calculated by Kaplan-Meier analysis were 354 and 279 days, respectively. In conclusion, according to our 3-year experience, Y90 SIR-Spheres radioembolization is a feasible and safe method to treat CRC liver metastases, with an acceptable level of complications and a good response rate.

Functional imaging of colorectal cancer: positron emission tomography, magnetic resonance imaging, and computed tomography

In the past 10 years, overall survival and disease-free survival of patients with colorectal cancer (CRC) has improved substantially because of a combination of factors: (1) more accurate staging as a result of advances in imaging technology; (2) refinements in surgical technique; (3) 'curative' metastasectomy for patients with limited metastatic disease; (4) improvements in radiation therapy planning and greater precision of radiation therapy delivery; and (5) increasing chemotherapeutic options, including antiangiogenic and vascular targeting drugs. In this era of 'personalized medicine,' the increasingly individualized treatment of patients with CRC has highlighted the need for functional imaging techniques in addition to conventional anatomic-based imaging. This review discusses the contribution of positron emission tomography to the clinical management of CRC. In addition, evolving techniques such as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), DCE computed tomography (perfusion CT), diffusion-weighted MRI, and blood oxygenation level-dependent MRI that might have a future role will be covered.

Yttrium-90 microsphere radioembolization for the treatment of liver malignancies: a structured meta-analysis

Radioembolization with yttrium-90 microspheres ((90)Y-RE), either glass- or resin-based, is increasingly applied in patients with unresectable liver malignancies. Clinical results are promising but overall response and survival are not yet known. Therefore a meta-analysis on tumor response and survival in patients who underwent (90)Y-RE was conducted. Based on an extensive literature search, six groups were formed. Determinants were cancer type, microsphere type, chemotherapy protocol used, and stage (deployment in first-line or as salvage therapy). For colorectal liver metastases (mCRC), in a salvage setting, response was 79% for (90)Y-RE combined with 5-fluorouracil/leucovorin (5-FU/LV), and 79% when combined with 5-FU/LV/oxaliplatin or 5-FU/LV/irinotecan, and in a first-line setting 91% and 91%, respectively. For hepatocellular carcinoma (HCC), response was 89% for resin microspheres and 78% for glass microspheres. No statistical method is available to assess median survival based on data presented in the literature. In mCRC, (90)Y-RE delivers high response rates, especially if used neoadjuvant to chemotherapy. In HCC, (90)Y-RE with resin microspheres is significantly more effective than (90)Y-RE with glass microspheres. The impact on survival will become known only when the results of phase III studies are published.

Multimodality imaging can predict the metabolic response of unresectable colorectal liver metastases to radioembolization therapy with Yttrium-90 labeled resin microspheres

Selective internal radiotherapy (SIRT) using Yttrium-90 labeled resin microspheres is increasingly used for the radioembolization of unresectable liver metastases of colorectal cancer (CRC). The treatment can be simulated by scintigraphy with Tc(99m)-labeled macroaggregates of albumin (MAA). The aim of the study was to develop a predictive dosimetric model for SIRT and to validate it by correlating results with the metabolic treatment response. The simulation of the dosimetry was performed by mathematically converting all liver voxel MAA-SPECT uptake values to the absolute Y(90) activity. The voxel values were then converted to a simulated absorbed dose (Gy) using simple MIRD formalism. The metabolic response was defined as the change in total lesion glycolysis (TLG) on FDG-PET. A total of 39 metastatic liver lesions were studied in eight evaluable patients. The mean administered Y(90) activity was 1.69 GBq (range: 1.33-2.04 GBq). The median (95% CI) simulated absorbed dose (Gy) was 29 Gy (1–98 Gy) and 66 Gy(32–159 Gy) in the poor (<50% TLG change) and the good responders (TLG change > 50%),respectively [DOSAGE ERROR CORRECTED].Using a simple cut-off value of 1 for the MAA-tumor-to-normal uptake ratio, a significant metabolic response was predicted with a sensitivity of 89% (17/19), a specificity of 65% (13/20), a positive predictive value of 71% (17/24) and a negative predictive value of 87% (13/15). Integrated multimodality imaging allows prediction of metabolic response post radioembolization using Y(90)-resin microspheres, and should be used for patient selection.

An uncommon cause of gastro-duodenal ulceration

Gastrointestinal ulcers occur frequently and are mainly caused by H pylori infection. In this report, we present a rare case of gastro-duodenal ulcer following selective internal radiation therapy (SIRT). SIRT is a palliative treatment for unresectable liver tumours. During SIRT, ⁹⁰Y-microspheres are infused into the hepatic artery. Pre-treatment evaluation for the presence of arterial shunts to neighbouring organs should be determined in order to avoid complications of SIRT.

Surgical therapy for colorectal metastases to the liver

Colorectal cancer is the fourth most common type of cancer in the West and the second leading cause of cancer-related deaths in the United States. Approximately 35 to 55% of patients with colorectal cancer develop hepatic metastases during the course of their disease. Surgical resection of colorectal liver metastases represents the only chance at potential cure, and long-term survival can be achieved in 35 to 58% of patients after resection. The goal of hepatic resection should be to resect all metastases with negative histologic margins while preserving sufficient functional hepatic parenchyma. In patients with extensive metastatic disease who would otherwise be unresectable, ablative approaches can be used instead of or combined with hepatic resection. The use of portal vein embolization and preoperative chemotherapy may also expand the population of patients who are candidates for surgical treatment. Despite these advances, many patients still experience a recurrence after hepatic resection. More active systemic chemotherapy agents are now available and are being increasingly employed as adjuvant therapy either before or after surgery. Modern treatment of colorectal liver metastasis requires a multidisciplinary approach in an effort to increase the number of patients who may benefit from surgical treatment of colorectal cancer liver metastasis.

Clinical and imaging experience with yttrium-90 microspheres in the management of unresectable liver tumours

INTRODUCTION

Selective internal radiation therapy (SIRT) is emerging as a new therapeutic modality in recent years for management of non-resectable hepatic malignancies. Our experience in clinical application of this treatment is reported here.

MATERIAL AND METHODS

From June 2004, patients whose liver tumours were no longer amenable for any conventional treatment with either chemotherapy or surgery were considered for yttrium-90 microspheres treatment after discussion at our multidisciplinary meeting. A pre-treatment planning was carried out with visceral angiography and technetium-99m macroaggregated albumin (MAA) for assessment of both tumour volume and extrahepatic shunting in addition to a baseline PET and CT scans, respectively. Two weeks later, a second visceral angiogram was performed to deliver the calculated dosage of microspheres into the arterial system supplying the tumour. Patients were then followed up with tumour markers, repeat PET and CT scans of abdomen at 6 weeks and 3 monthly thereafter.

RESULT

Twenty-one patients (F=11, M=10; age range 40-75 years, mean=58 years) received yttrium-90 microspheres consisting of liver metastases from colorectal primary (n=10) and non-colorectal primaries (n=8), and primary liver tumours (n=3). One patient received 2 treatments. The mean administered activity of microspheres delivered was 1.9 GBq (range 1.2-2.5 GBq). Injection of microspheres had no immediate effect on either clinical haematology or liver function tests. At follow-up, 86% of patients showed decreased activity on PET scan at 6 weeks (p=0.01). The mean pre-treatment SUV was 12.2+/-3.7 and the mean post-treatment SUV was 9.3+/-3.7, indicating a significant improvement measured with PET activity. Only 13% showed a reduction in the size of tumour on CT scan. For patients with colorectal liver metastases, there was no significant reduction in CEA level (127+/-115 vs 75+/-72 micro/l, p=0.39). Complications were seen in 4 patients (19%) including radiation hepatitis (n=2), cholecystitis (n=1) and duodenal ulceration (n=1). All resolved without surgical intervention. Seven patients died at follow-up from progressive extrahepatic disease (33%).

CONCLUSION

SIRT should be considered for patients with advanced liver cancer. It has a significant effect on liver disease in the absence of extrahepatic disease. PET imaging has an integral role in the assessment of patients treated with yttrium-90 SIR-Spheres.

Response of liver metastases after treatment with yttrium-90 microspheres: role of size, necrosis, and PET

OBJECTIVE

Yttrium-90 radioembolization is an emerging treatment for liver malignancies. The purpose of this study was to evaluate the imaging response of liver metastases to 90Y microspheres based on size and necrosis criteria using CT and comparing the results to PET and to describe imaging features related to 90Y therapy.

MATERIALS AND METHODS

We reviewed the imaging studies of 42 patients with unresectable liver metastases treated with lobar radioembolization with 90Y. CT response was determined using traditional size criteria (World Health Organization [WHO] and Response Evaluation Criteria in Solid Tumors [RECIST]), necrosis criteria, and combined criteria (RECIST and necrosis). We compared the response on CT with the response on PET. Complications of treatment were assessed.

RESULTS

The response rate was 19% (8/42) by WHO criteria, 24% (10/42) by RECIST, 45% (19/42) by necrosis criteria, and 50% (21/42) by combined criteria. Stabilization of lesion size occurred in 50% of patients. Necrosis and combined criteria identified responders earlier than RECIST and WHO criteria. Seven responders by combined criteria had an increase in lesion size on initial follow-up and would have been considered nonresponders. PET scans were obtained in 23 patients (33 treated lobes). PET detected significantly more responses to treatment (21/33, 63%) than CT using RECIST (2/33, 6%) or combined criteria (8/33, 24%) (p < 0.05, McNemar test). Complications of treatment included radiation cholecystitis (10 patients, 23%) and liver edema (18 patients, 42%).

CONCLUSION

The use of necrosis and size criteria on CT and correlation with PET may improve the accuracy of assessment of response to 90Y treatment in patients with liver metastases and detect response earlier than standard size criteria.

Assessment of response to treatment of unresectable liver tumours with 90Y microspheres: value of FDG PET versus computed tomography

INTRODUCTION

Selective internal radiation therapy (SIRT) with SIR spheres (90Y microspheres) is a treatment option for liver tumours in patients in whom other therapies are inappropriate or have failed. This study aims to assess the value of FDG PET in assessing the response to SIRT as compared to computed tomography (CT).

MATERIAL AND METHODS

Twenty-one patients (11 F, 10 M; age range 40-75 years, mean, 58 years) received SIR spheres at the Hammersmith Hospital. One patient received two treatments. Most patients had colorectal metastases (n=10), while the others (n=11) had liver metastasis from different primaries. The mean administered dose was 1.9 GBq (range, 1.2-2.5 GBq). Follow-up was done with FDG PET and CT at 6 weeks, and 6-monthly thereafter. Pre-therapy and post-therapy CT and PET scans were assessed visually (RECIST criteria for CT) and semi-quantitative for PET using the standardized uptake value (SUV).

RESULT

Eighty-six percent of patients showed decreased PET activity at 6 weeks while only 13% showed a partial response in the size of tumour on CT scan. The mean pre-treatment SUV was 12.2+/-3.7 and the mean post-treatment SUV was 9.3+/-3.7 (P=0.01). CT imaging showed progressive disease in 27% patients and stable liver disease in 60% patients. Based on FDG PET results one patient had surgery for down-staged tumour.

CONCLUSION

FDG PET imaging is more sensitive than CT in the assessment of early response to SIR spheres, allowing clinicians to proceed with further therapeutic options.

Gastrointestinal tract malignancies and positron emission tomography: an overview

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is highly accurate in restaging colorectal cancer, esophageal cancer, and gastrointestinal stromal tumors. Overall, it compares favorably with anatomical imaging in the evaluation of tumor recurrence because metabolic abnormalities usually precede a structural change. Initial staging of these malignancies with PET is best used in patients with locally advanced disease who may benefit from curative resection if distant metastases are not found. It also appears to have great potential in predicting histopathologic response to neoadjuvant therapy and in monitoring the success of radiofrequency ablation and (90)Y microspheres radioembolization soon after intervention. FDG-PET can be used in other gastrointestinal malignancies as a prognostic tool and to detect distant disease but its role has not yet been well defined.

Radioembolization with 90Yttrium Microspheres: A State-of-the-Art Brachytherapy Treatment for Primary and Secondary Liver Malignancies

Yttrium-90 microspheres are increasingly being used as a treatment modality for primary and secondary liver tumors. As these therapies continue to be accepted, it is natural that their application in more complex clinical scenarios will become more common. This article is meant to introduce these controversies and to generate interest and dialogue by the interventional oncology community. This discussion is based on more than 900 (90)Y radioembolization procedures performed over a 5-year period.

Localized internal radiotherapy with 90Y particles embedded in a new thermosetting alginate gel: A feasibility study in pigs

BACKGROUND

Internal radiotherapy requires the localization of the radionuclide to the site of action. A new injectable alginate gel formulation intended to undergo immediate gelation in tissues and capable of encapsulating radioactive particles containing 90Y was investigated.

METHODS

The formulation was injected intramuscularly, into the bone marrow compartment of the femur and intravenously, respectively, in pigs. The distribution of radioactivity in various tissues was determined.

RESULTS

Following intramuscular injection, more than 90% of the radioactivity was found at the site of injection. Following injection into bone marrow, 30-40% of the radioactivity was retained at the site of injection, but a considerable amount of radioactivity was also detected in the lungs (35-45%) and the liver (5-18%). Following intravenous injection, 80-90% of the radioactivity was found in the lungs.

CONCLUSION

The present formulation appears suitable for localized radiotherapy in organs and tissues having low perfusion.