Microsphere Localization and Dose Quantification Using Positron Emission Tomography/CT following Hepatic Intraarterial Radioembolization with Yttrium-90 in Patients with Advanced Hepatocellular Carcinoma

PurposeTo characterize the distribution of absorbed radiation dose after glass microsphere radioembolization for hepatocellular carcinoma (HCC) using yttrium-90 (⁹⁰Y) positron emission tomography/computed tomography (PET/CT).Materials and MethodsIn this retrospective study, 64 ⁹⁰Y PET/CT scans performed after treatment were evaluated following ⁹⁰Y glass-bead radioembolization in patients with advanced HCC. The intended dose to the target volume ranged from 83–129 Gy. Three-dimensional “dose maps” were created from reconstructed PET images using a voxel-based S-value transformation. Liver parenchyma and liver tumors were contoured on cross-sectional imaging and aligned with the created dose maps.ResultsThere were 113 tumors examined as part of 64 lobar treatments. The average tumor size was 4.8 cm ± 4.0 with an average tumor dose of 173 Gy ± 109. The average dose to the nontumor parenchyma within the target volume was 93.4 Gy ± 32.6, with on average 50% of the parenchymal voxels receiving > 79 Gy ± 23 and 10% receiving > 173 Gy ± 55. The average and median tumor-to-parenchymal weighted dose ratios were 2.2 and 1.9, respectively.ConclusionsUsing recommended dosimetry and administration techniques for lobar glass microsphere radioembolization, high doses to target tumors as well as background parenchyma were achieved on average with modest preferential uptake within tumors. There was wide variation in measured tumor and parenchymal doses after hepatic radioembolization for HCC, suggesting the need for continued development of patient-specific dosimetry.     

Comparison of Positron Emission Tomography and Bremsstrahlung Imaging to Detect Particle Distribution in Patients Undergoing Yttrium-90 Radioembolization for Large Hepatocellular Carcinomas or Associated Portal Vein Thrombosis

PurposeTo compare positron emission tomography/computed tomography (PET/CT) imaging with bremsstrahlung single photon emission computed tomography (SPECT) in patients after yttrium-90 (⁹⁰Y) microsphere radioembolization to assess particle uptake.Materials and MethodsThis prospective study comprised patients with large (> 5 cm) hepatocellular carcinoma (HCC) or tumor-associated portal vein thrombus (PVT), or both. After radioembolization for HCC, patients underwent bremsstrahlung SPECT/CT and time-of-flight PET/CT imaging of ⁹⁰Y without additional tracer administration. Follow-up imaging and toxicity was analyzed. Imaging analyses of PET/CT and bremsstrahlung SPECT/CT were independently performed.ResultsThere were 13 patients enrolled in the study, including 7 with PVT. Median tumor diameter was 7 cm. PET/CT demonstrated precise localization of ⁹⁰Y particles in the liver, with specific patterns of uptake in large tumors. In cases of PVT, PET/CT showed activity within the PVT. When correlated to short-term follow-up imaging, areas of necrosis correlated with regions of uptake seen on PET/CT. Compared with bremsstrahlung imaging, PET/CT demonstrated at least comparable spatial resolution with less scatter. Quantitative uptake in nontreated regions of interest showed significantly reduced scatter with PET/CT versus SPECT/CT (1% vs 14%, P < .001).ConclusionsEvaluation of ⁹⁰Y particle uptake with PET/CT potentially demonstrates high spatial resolution and low scatter compared with bremsstrahlung SPECT/CT. Confirmation of particles within PVT on PET/CT correlates with response on follow-up imaging and may account for the efficacy of radioembolization in patients with PVT.     

A Simple Method for Estimating Dose Delivered to Hepatocellular Carcinoma after Yttrium-90 Glass-Based Radioembolization Therapy: Preliminary Results of a Proof of Concept Study

PurposeTo investigate a simple semiquantitative method to estimate yttrium-90 (⁹⁰Y) dose delivered with radioembolization to infiltrative hepatocellular carcinoma (HCC).Materials and MethodsIn a prospective study, patients with infiltrative HCC and portal vein thrombosis (PVT) underwent glass-based ⁹⁰Y radioembolization including technetium-99m macroaggregated albumin (^99mTc-MAA) hepatopulmonary shunt study before therapy and bremsstrahlung single photon emission computed tomography (SPECT)/computed tomography (CT) after ⁹⁰Y radioembolization. Baseline magnetic resonance imaging was coregistered with ^99mTc-MAA and bremsstrahlung SPECT/CT imaging separately. Unit tumor activity (⁹⁰Y radioactivity delivered to each cubic centimeter of tumor) was estimated based on a lobar infusion approach. Correlation between proportions of ^99mTc-MAA and ⁹⁰Y delivered to the tumor was investigated. Survival analysis was performed using Kaplan-Meier estimations.Results⁹⁰Y therapy was administered in 18 consecutive patients (median age, 55.3 y; mean tumor volume, 588 cm³). Higher intratumoral ⁹⁰Y dose predicted prolonged survival, with 13.2-month median survival in patients with HCC and mean ⁹⁰Y dose of ≥ 100 Gy versus 4.6-month median survival for other patients (P < .001). Of administered ⁹⁰Y dose, 51.9% was delivered to the targeted tumors compared with 74.1% of ^99mTc-MAA with linear correlation between biodistribution of ^99mTc-MAA and ⁹⁰Y observed (Pearson r = 0.774, P < .001).ConclusionsThe findings in this study suggest that approximately 50% of administered ⁹⁰Y dose is taken up by targeted infiltrative HCC with PVT. Intratumoral ⁹⁰Y dose ≥ 100 Gy in unresectable infiltrative HCC via a lobar intraarterial approach is a positive prognostic factor for survival.     

Outpatient Single-Session Yttrium-90 Glass Microsphere Radioembolization

PurposeTo investigate the feasibility of yttrium-90 (⁹⁰Y) glass microsphere radioembolization (including angiography, lung shunt assessment, and treatment) as a single-session, outpatient procedure.Materials and MethodsBetween January 2008 and June 2013, 14 patients underwent outpatient, single-session radioembolization with ⁹⁰Y glass microspheres. As part of the routine diagnostic work-up, all patients underwent either computed tomography (CT) or magnetic resonance imaging of the liver with three-dimensional analysis and had laboratory results forwarded to our center for confirmation of candidacy before treatment. On treatment day, all patients underwent planning mesenteric angiography with flat panel cone-beam CT imaging. Patients were administered 33–85 MBq of technetium-99m macroaggregated albumin (^99mTc-MAA) via a microcatheter positioned in a hepatic artery supplying the tumor of interest. Planar scintigraphy was initiated within 2 hours after the administration of ^99mTc-MAA and lung shunt fraction was determined. Final dosimetry calculations were performed while the patient was being transferred back from nuclear medicine to interventional radiology.ResultsAll patients successfully underwent planning angiography with administration of ^99mTc-MAA and ⁹⁰Y radioembolization as a single-session treatment. There were no reportable or recordable medical events; treatment was carried out to the desired dose in all cases. The mean total procedure time was 2.70 hours ± 0.72 (range, 1.63–3.97 h).ConclusionsThis study reports a novel proof of concept for performing radioembolization in a single-session setting. By using the described method, time between initial clinical assessments and radioembolization treatment is decreased, and costs are minimized.     

Superselective Yttrium-90 Radioembolization for Hepatocellular Carcinoma Yields High Response Rates with Minimal Toxicity

PurposeTo assess the safety and efficacy of yttrium-90 (⁹⁰Y) radioembolization when performed in a superselective fashion for patients with unresectable hepatocellular carcinoma (HCC).Materials and MethodsThis retrospective study included 20 patients with unresectable HCC. Median Model for End-Stage Liver Disease score was 10.5 (range, 6–25), with 8 of 20 patients (40%) classified Child-Pugh class B and 1 of 20 patients (5%) classified class C cirrhosis. Segmental tumor-associated portal vein thrombus was present in 12 patients (60%), and a transjugular intrahepatic portosystemic shunt was present in 4 patients (20%). Median tumor diameter was 3.9 cm (range, 2.5–7.1 cm). All patients underwent superselective ⁹⁰Y radioembolization targeted to a single liver segment using glass microspheres.ResultsMedian dose to the treated segment was 254 Gy, and median dose to the tumor was 536 Gy. No grade 3–4 hepatotoxicity occurred. The most common clinical toxicities were fatigue (30%), abdominal pain (10%), and postembolization syndrome (10%). Follow-up imaging demonstrated complete European Association for the Study of the Liver response of the index tumor in 19 of 20 patients (95%) and stable disease in 1 of 20 patients (5%). In patients with complete response, local tumor recurrence rate was 5.3% (1 of 19 patients). Median time to progression was 319 days. Overall survival was 90% (18 of 20 patients) with a median follow-up period of 275 days (range, 32–677 d).ConclusionsWhen performed in a segmental fashion, ⁹⁰Y radioembolization demonstrates high response rates and low local tumor recurrence rates. Complete imaging response can be achieved in patients with locally aggressive disease. This study demonstrates no clinically significant hepatotoxicity, despite moderate liver dysfunction in many patients.     

Intraprocedural Yttrium-90 Positron Emission Tomography/CT for Treatment Optimization of Yttrium-90 Radioembolization

Radioembolization with yttrium-90 (⁹⁰Y) microspheres relies on delivery of appropriate treatment activity to ensure patient safety and optimize treatment efficacy. We report a case in which ⁹⁰Y positron emission tomography (PET)/computed tomography (CT) was performed to optimize treatment planning during a same-day, three-part treatment session. This treatment consisted of (i) an initial ⁹⁰Y infusion with a dosage determined using an empiric treatment planning model, (ii) quantitative ⁹⁰Y PET/CT imaging, and (iii) a secondary infusion with treatment planning based on quantitative imaging data with the goal of delivering a specific total tumor absorbed dose.     

Yttrium-90 Radioembolization Stops Progression of Targeted Breast Cancer Liver Metastases after Failed Chemotherapy

PurposeTo determine, in an open-label, retrospective report, the safety and effectiveness of locoregional therapy with yttrium-90 (⁹⁰Y) radioembolization for patients with progressing breast cancer liver metastases (BCLMs) despite multi-agent chemotherapy.Materials and MethodsSeventy-five patients with progressing BCLMs and stable extrahepatic disease were treated with radioembolization at a single institution. Retrospective review of a prospectively collected database was performed to evaluate clinical and biochemical toxicities, tumor response, overall survival (OS), and time to progression. Radiologic response assessments included Response Evaluation Criteria In Solid Tumors in primary index lesions and metabolic activity on positron emission tomography (PET). Univariate and multivariate analyses were performed.ResultsThe mortality rate at 30 days was 4% (n = 3). Clinical toxicity and hyperbilirubinemia of grade 3 or worse occurred in 7.6% (n = 5) and 5.9% of patients (n = 4), respectively. Partial response (PR) was seen in 35.3% of patients (n = 24), stable disease (SD) in 63.2% (n = 43), and progressive disease in 1.5% (n = 1). PET imaging was available in 25 patients, and 21 (84%) had a complete response, PR, or SD. The median OS was 6.6 months (95% confidence interval [CI], 5.0–9.2 mo). The hazard ratio (HR) for OS on multivariate analysis was 0.39 (95% CI, 0.23–0.66) for tumor burden less than 25% compared with greater burden. Elevated bilirubin levels were shown to reduce OS. The HR for hepatic progression was 0.22 (95% CI, 0.05–0.98) for solitary versus multifocal disease.ConclusionsLocoregional therapy with ⁹⁰Y radioembolization is safe and stops or delays the progression of targeted chemorefractory BCLMs. Adverse prognosticators were identified.     

Early Treatment Response Evaluation after Yttrium-90 Radioembolization of Liver Malignancy with CT Perfusion

PurposeTo evaluate computed tomography (CT) perfusion for assessment of early treatment response after transarterial radioembolization of patients with liver malignancy.Materials and MethodsDynamic contrast-enhanced CT liver perfusion was performed before and 4 weeks after transarterial radioembolization in 40 patients (25 men and 15 women; mean age, 64 y ± 11; range, 35–80 y) with liver metastases (n = 27) or hepatocellular carcinoma (HCC) (n = 13). Arterial perfusion (AP) of tumors derived from CT perfusion and tumor diameters were measured on CT perfusion before and after transarterial radioembolization. Success of transarterial radioembolization was evaluated on morphologic follow-up imaging (median follow-up time, 4 mo) based on Response Evaluation Criteria in Solid Tumors (Version 1.1). CT perfusion parameters before and after transarterial radioembolization for different response groups were compared. Kaplan-Meier curves were plotted to illustrate overall 1-year survival rates.ResultsLiver metastases showed significant differences in AP before and after transarterial radioembolization in responders (P < .05) but not in nonresponders (P = .164). In HCC, AP values before and after transarterial radioembolization were not significantly different in responders and nonresponders (P = .180 and P = .052). Tumor diameters were not significantly different on CT perfusion before and after transarterial radioembolization in responders and nonresponders with liver metastases and HCC (P = .654, P = .968, P = .148, P = .164). In patients with significant decrease of AP in liver metastases after transarterial radioembolization, 1-year overall survival was significantly higher than in patients showing no reduction of AP.ConclusionsCT perfusion showed early reduction of AP in liver metastases responding to transarterial radioembolization; tumor diameter remained unchanged early after treatment. No significant early treatment response to transarterial radioembolization was found in patients with HCC. In patients with liver metastases, a decrease of AP after transarterial radioembolization was associated with a higher 1-year overall survival rate.     

Modified Response Evaluation Criteria in Solid Tumors and European Association for the Study of the Liver Criteria Using Delayed-Phase Imaging at an Early Time Point Predict Survival in Patients with Unresectable Intrahepatic Cholangiocarcinoma following Yttrium-90 Radioembolization

PurposeTo investigate early imaging prognostic factors in unresectable intrahepatic cholangiocarcinoma (ICC) refractory to standard chemotherapy after yttrium-90 (⁹⁰Y) radioembolization therapy.Materials and MethodsIn an institutional review board–approved prospective correlative study, 21 consecutive patients with ICC refractory to standard chemotherapy underwent ⁹⁰Y radioembolization therapy. Target and overall Response Evaluation Criteria In Solid Tumors (RECIST), modified RECIST (mRECIST), and European Association for the Study of the Liver (EASL) treatment responses were assessed. The mRECIST and EASL criteria were modified for application on delayed phases of dynamic contrast-enhanced cross-sectional imaging studies. Conventional definitions for complete and partial response were applied; these responses comprised objective response. Restaging imaging was obtained at 1- and 3-month intervals until patient death. Survival analyses by Kaplan–Meier and log-rank proportional models including application of the landmark method to avoid lead-time bias were performed from the day of treatment. Significance was set at P < .05.ResultsMedian overall survival (OS) from the time of ⁹⁰Y therapy was 16.3 months (95% confidence interval, 7.2–25.4 mo). Significant differences between mRECIST and EASL versus RECIST were found when categorizing patients into responders and nonresponders (P < .001). Significantly prolonged OS was observed for patients with targeted objective response based on modified mRECIST and EASL criteria (P = .005 and P = .001, respectively) at 3 months. RECIST was not found to correlate with survival at 1- or 3-month follow-up.ConclusionsModified target mRECIST and EASL criteria that employ delayed-phase contrast enhancement at 3 months after ⁹⁰Y radioembolization therapy for ICC predicted OS. RECIST did not correlate with survival.     

Comparative Study of Staging Systems for Hepatocellular Carcinoma in 428 Patients Treated with Radioembolization

PurposeTo compare the utility of different staging systems and analyze independent predictors of survival in patients with hepatocellular carcinoma (HCC) treated with yttrium-90 (⁹⁰Y) radioembolization.Materials and MethodsDuring the period 2004–2011, 428 patients with HCC were treated with ⁹⁰Y radioembolization. All patients were staged prospectively by the following staging systems: Child-Turcotte-Pugh (CTP), United Network for Organ Sharing, Barcelona Clinic Liver Cancer (BCLC), Okuda classification, Cancer of the Liver Italian Program (CLIP), Groupe d’Etude et de Traitement du Carcinome Hepatocellulaire, Chinese University Prognostic Index, and Japan Integrated Staging. The ability of the staging systems to predict survival was assessed. The staging systems were compared using Cox proportional hazards regression model, linear regression, Akaike information criterion (AIC), and concordance index (C-index). Univariate and multivariate analyses were employed to assess independent predictors of survival.ResultsWhen tested independently, all staging systems exhibited significant ability to discriminate early (long survival) from advanced (worse survival) disease. CLIP provided the most accurate information in predicting survival outcomes (AIC = 2,993, C-index = 0.8503); CTP was least informative (AIC = 3,074, C-index = 0.6445). Independent predictors of survival included Eastern Cooperative Oncology Group performance status grade 0 (hazard ration [HR], 0.56; confidence interval [CI], 0.34–0.93), noninfiltrative tumors (HR, 0.62; CI, 0.44–0.89), absence of portal venous thrombosis (HR, 0.60; CI, 0.40–0.89), absence of ascites (HR, 0.56; CI, 0.40–0.76), albumin ≥ 2.8 g/dL (HR, 0.72; CI, 0.55–0.94), alkaline phosphatase ≤ 200 U/L (HR, 0.68; CI, 0.50–0.92), and α-fetoprotein ≤ 200 ng/mL (HR, 0.67; CI, 0.51–0.86).ConclusionsCLIP was most accurate in predicting survival in patients with HCC. Given that not all patients receive the recommended BCLC treatment strategy, this information is relevant for clinical trial design and predicting long-term outcomes after ⁹⁰Y radioembolization.     

Yttrium-90 Radioembolization as a Bridge to Liver Transplantation: A Single-Institution Experience

PurposeTo evaluate our experience with the use of yttrium-90 (⁹⁰Y) radioembolization in maintaining potential candidacy and, in some instances, downstaging hepatocellular carcinoma (HCC) that does not meet Milan criteria for liver transplantation.Materials and MethodsA retrospective review of 20 consecutive patients with HCC who were listed to receive a liver transplant and were treated with ⁹⁰Y radioembolization as a sole modality for locoregional “bridge” therapy was performed. Demographics, radiographic and pathologic response, survival, and recurrences were examined.ResultsTwenty-two ⁹⁰Y treatments were performed in 20 patients before transplantation. Median time from first treatment to transplantation was 3.5 months. HCC in 14 patients met the Milan criteria at the time of the first ⁹⁰Y treatment, and HCC in six did not. All cases that originally met the Milan criteria remained within the criteria before transplantation, and two of six patients whose disease did not meet the criteria (33%) had their disease successfully downstaged to meet the criteria. Overall, nine patients (45%) had complete or partial radiologic response to ⁹⁰Y radioembolization according to modified Response Evaluation Criteria In Solid Tumors. Complete necrosis of tumor with no evidence of viable tumor on pathologic examination was observed in five patients (36%) whose disease met the Milan criteria.ConclusionsParticularly in regions with long wait list times, ⁹⁰Y treatment is effective in maintaining tumor size in potential liver transplantation candidates with HCC. In addition, it can also be considered as a downstaging therapy in select patients before transplantation.     

High-Frequency Jet Ventilation under General Anesthesia Facilitates CT-Guided Lung Tumor Thermal Ablation Compared with Normal Respiration under Conscious Analgesic Sedation

PurposeTo determine whether technical difficulty of computed tomography (CT)–guided percutaneous lung tumor thermal ablations is altered with the use of high-frequency jet ventilation (HFJV) under general anesthesia (GA) compared with procedures performed with normal respiration (NR) under conscious sedation (CS).Materials and MethodsThermal ablation treatment sessions performed with NR under CS or HFJV under GA with available anesthesia records and CT fluoroscopic images were retrospectively reviewed; 13 and 33 treatment sessions, respectively, were identified. One anesthesiologist determined the choice of anesthesiologic technique independently. Surrogate measures of procedure technical difficulty—time duration, number of CT fluoroscopic acquisitions, and radiation dose required for applicator placement for each tumor—were compared between anesthesiologic techniques. The anesthesiologist time and complications were also compared. Parametric and nonparametric data were compared by Student independent-samples t test and χ² test, respectively.ResultsPatients treated with HFJV under GA had higher American Society of Anesthesiologists classifications (mean, 2.66 vs 2.23; P = .009) and smaller lung tumors (16.09 mm vs 27.38 mm; P = .001). The time duration (220.30 s vs 393.94 s; P = .008), number of CT fluoroscopic acquisitions (10.31 vs 19.13; P = .023), and radiation dose (60.22 mGy·cm vs 127.68 mGy·cm; P = .012) required for applicator placement were significantly lower in treatment sessions performed with HFJV under GA. There was no significant differences in anesthesiologist time (P = .20), rate of pneumothorax (P = .62), or number of pneumothoraces requiring active treatment (P = .19).ConclusionsHFJV under GA appears to reduce technical difficulty of CT-guided percutaneous applicator placement for lung tumor thermal ablations, with similar complication rates compared with treatment sessions performed with NR under CS. The technique is safe and may facilitate treatment of technically challenging tumors.     

Comparative study of post-transplant outcomes in hepatocellular carcinoma patients treated with chemoembolization or radioembolization

PurposeTo analyze long-term outcomes in patients bridged/downstaged to orthotopic liver transplantation (OLT) by transarterial chemoembolization (TACE) or yttrium-90 radioembolization (Y90) for hepatocellular carcinoma (HCC).Methods172 HCC patients who underwent OLT after being treated with transarterial liver-directed therapies (LDTs) (Y90: 93; TACE: 79) were identified. Pre-LDT and pre-OLT clinical/imaging/laboratory characteristics including United Network for Organ Sharing (UNOS) staging and alpha-fetoprotein values (AFP) were tabulated. Post-OLT HCC recurrence was assessed by imaging follow-up per standard of care. Recurrence-free (RFS) and overall survival (OS) were calculated. Uni/multivariate and sub-stratification analyses were performed.ResultsTime-to-OLT was longer in the Y90 group (Y90: 6.5 months; TACE: 4.8 months; p = 0.02). With a median post-OLT follow-up of 26.1 months (IQR: 11.1–49.7), tumor recurrence was found in 6/79 (8%) TACE and 8/93 (9%) Y90 patients. Time-to-recurrence was 26.6 (CI: 7.0–49.5) and 15.9 months (CI: 7.8–46.8) for TACE and Y90, respectively (p = 0.48). RFS (Y90: 79 months; TACE: 77 months; p = 0.84) and OS (Y90: 57% alive at 100 months; TACE: 84.2 months; p = 0.57) were similar. 54/155 patients (Y90: 29; TACE: 25) were downstaged to UNOS T2 or less. RFS hazard ratios for patients downstaged to ≤T2 versus those that were not were 0.6 (CI: 0.33–1.1) and 1.7 (CI: 0.9–3.1) respectively (p = 0.13). 17/155 patients (Y90: 8; TACE: 9) that were >T2 were downstaged to UNOS T2 or less (within transplant criteria). Distribution (unilobar/bilobar), AFP, and pre-transplant UNOS stage affected RFS on univariate analyses.ConclusionDespite longer time-to-OLT for Y90 patients, post-OLT outcomes were similar between patients bridged or downstaged by TACE or Y90. A trend towards improved RFS for downstaged patients was identified.     

Predictive Value of Pattern Classification 24 Hours after Radiofrequency Ablation of Liver Metastases on CT and Positron Emission Tomography/CT

PurposeTo assess a classification scheme for predicting local tumor progression (LTP) after radiofrequency (RF) ablation of liver metastases, using predefined patterns on contrast-enhanced computed tomography (CT) and positron emission tomography (PET) combined with CT (PET/CT) acquired 24 hours after RF ablation.Materials and MethodsThere were 45 metastases in 20 patients treated. After 24 hours, imaging of the ablation zones was performed with contrast-enhanced PET/CT. Three independent radiologists prospectively assessed contrast-enhanced CT and combined PET/CT images to identify three patterns: pattern I, no tissue enhancement or fluorodeoxyglucose uptake between the ablation zone and the liver parenchyma; pattern II, a rimlike pattern; and pattern III, a peripheral nodule. PET/CT images obtained after 8–10 weeks were evaluated for LTP. The patterns were analyzed for their sensitivity, specificity, positive predictive value, and negative predictive value for predicting LTP.ResultsPattern I was most frequently observed (81% for contrast-enhanced CT and 61% for PET/CT) as well as for ablation zones that showed LTP (52% and 37%, respectively). Conversely, pattern II was observed for tumors that were completely ablated (6% and 29%, respectively). Patterns II and III together had the highest sensitivity for predicting LTP (48% and 63%, respectively); pattern III had the highest specificity (94% and 95%, respectively). For nodular patterns, test characteristics were better for PET/CT compared with contrast-enhanced CT, but the difference was not significant. Nodular patterns > 1 cm achieved high positive predictive value (both 100%).ConclusionsInflammation and hyperemia can hinder interpretation on imaging 24 hours after RF ablation, especially on PET/CT. Nodular patterns around the ablation zone on early contrast-enhanced CT and PET/CT have a high predictive value for LTP and should be taken into account for disease management.     

Quantitative Assessment of Lipiodol Deposition after Chemoembolization: Comparison between Cone-Beam CT and Multidetector CT

PurposeTo evaluate the ability of cone-beam computed tomography (CBCT) performed directly after transarterial chemoembolization to assess ethiodized oil (Lipiodol) deposition in hepatocellular carcinoma (HCC) and compare it with unenhanced multidetector computed tomography (CT).Materials and MethodsConventional transarterial chemoembolization was used to treat 15 patients with HCC, and CBCT was performed to assess Lipiodol deposition directly after transarterial chemoembolization. Unenhanced multidetector CT was performed 24 hours after transarterial chemoembolization. Four patients were excluded because the margin of tumor or area of Lipiodol deposition was unclear. The image enhancement density of the entire tumor and liver parenchyma was measured by ImageJ software, and tumor-to-liver contrast (TLC) was calculated. In addition, volumetric measurement of tumor and Lipiodol was performed by semiautomatic three-dimensional volume segmentation and compared using linear regression to evaluate consistency between the two imaging modalities.ResultsThe mean value of TLC on CBCT was not significantly different from TLC on multidetector CT (337.7 HU ± 233.5 vs 283.0 HU ± 152.1, P = .103).The average volume of the whole tumor and of only the regions with Lipiodol deposition and the calculated average percentage of Lipiodol retention on CBCT were not significantly different compared with multidetector CT (tumor volume, 9.6 cm³ ± 11.8 vs 10.8 cm³ ± 14.2, P = .142; Lipiodol volume, 6.3 cm³ ± 7.7 vs 7.0 cm³ ± 8.1, P = .214; percentage of Lipiodol retention, 68.9% ± 24.0% vs 72.2% ± 23.1%, P = .578). Additionally, there was a high correlation in the volume of tumor and Lipiodol between CBCT and multidetector CT (R² = 0.919 and 0.903).ConclusionsThe quantitative image enhancement and volume analyses demonstrate that CBCT is similar to multidetector CT in assessing Lipiodol deposition in HCC after transarterial chemoembolization.     

Transcatheter CT Arterial Portography and CT Hepatic Arteriography for Liver Tumor Visualization during Percutaneous Ablation

PurposeTo evaluate the feasibility of combining transcatheter computed tomography (CT) arterial portography or transcatheter CT hepatic arteriography with percutaneous liver ablation for optimized and repeated tumor exposure.Materials and MethodsStudy participants were 20 patients (13 men and 7 women; mean age, 59.4 y; range, 40–76 y) with unresectable liver-only malignancies—14 with colorectal liver metastases (29 lesions), 5 with hepatocellular carcinoma (7 lesions), and 1 with intrahepatic cholangiocarcinoma (2 lesions)—that were obscure on nonenhanced CT. A catheter was placed within the superior mesenteric artery (CT arterial portography) or in the hepatic artery (CT hepatic arteriography). CT arterial portography or CT hepatic arteriography was repeatedly performed after injecting 30–60 mL 1:2 diluted contrast material to plan, guide, and evaluate ablation. The operator confidence levels and the liver-to-lesion attenuation differences were assessed as well as needle-to-target mismatch distance, technical success, and technique effectiveness after 3 months.ResultsTechnical success rate was 100%; there were no major complications. Compared with conventional unenhanced CT, operator confidence increased significantly for CT arterial portography or CT hepatic arteriography cases (P < .001). The liver-to-lesion attenuation differences between unenhanced CT, contrast-enhanced CT, and CT arterial portography or CT hepatic arteriography were statistically significant (mean attenuation difference, 5 HU vs 28 HU vs 70 HU; P < .001). Mean needle-to-target mismatch distance was 2.4 mm ± 1.2 (range, 0–12.0 mm). Primary technique effectiveness at 3 months was 87% (33 of 38 lesions).ConclusionsIn patients with technically unresectable liver-only malignancies, single-session CT arterial portography–guided or CT hepatic arteriography–guided percutaneous tumor ablation enables repeated contrast-enhanced imaging and real-time contrast-enhanced CT fluoroscopy and improves lesion conspicuity.     

Hepatic Blood Volume Imaging with the Use of Flat-Detector CT Perfusion in the Angiography Suite: Comparison with Results of Conventional Multislice CT Perfusion

PurposeTo prospectively determine the feasibility of flat-detector (FD) computed tomography (CT) perfusion to measure hepatic blood volume (BV) in the angiography suite in patients with hepatocellular carcinoma (HCC).Materials and MethodsTwenty patients with HCC were investigated with conventional multislice and FD CT perfusion. CT perfusion was carried out on a multislice CT scanner, and FD CT perfusion was performed on a C-arm angiographic system, before transarterial chemoembolization procedures. BV values of conventional and FD CT perfusion were measured within tumors and liver parenchyma. The arterial perfusion portion of CT perfusion BV was extracted from CT perfusion BV by multiplying it by a hepatic perfusion index. Relative values (RVs) for CT perfusion arterial BV and FD CT perfusion BV (FD BV) were defined by dividing BV of tumor by BV of parenchyma. Relationships between BV and RV values of these two techniques were analyzed.ResultsIn all patients, both perfusion procedures were technically successful, and all 33 HCCs larger than 10 mm were identified with both imaging methods. There were strong correlations between the absolute values of FD BV and CT perfusion arterial BV (tumor, r = 0.903; parenchyma, r = 0.920; both P < .001). Bland–Altman analysis showed a mean difference of −0.15 ± 0.24 between RVs for CT perfusion arterial BV and FD BV.ConclusionsThe feasibility of FD CT perfusion to assess BV values of liver tumor and surrounding parenchyma in the angiographic suite was demonstrated.     

Limitations of Body Surface Area–Based Activity Calculation for Radioembolization of Hepatic Metastases in Colorectal Cancer

PurposeTo calculate absorbed radiation doses in patients treated with resin microspheres prescribed by the body surface area (BSA) method and to analyze dose-response and toxicity relationships.Materials and MethodsA retrospective review was performed of 45 patients with colorectal carcinoma metastases who received single-session whole-liver resin microsphere radioembolization. Prescribed treatment activity was calculated using the BSA method. Liver volumes and whole-liver absorbed doses (D_WL) were calculated. D_WL was correlated with toxicity and radiographic and biochemical response.ResultsThe standard BSA-based administered activity (range, 0.85–2.58 GBq) did not correlate with D_WL (mean, 50.4 Gy; range, 29.8–74.7 Gy; r = −0.037; P = .809) because liver weight was highly variable (mean, 1.89 kg; range, 0.94–3.42 kg) and strongly correlated with D_WL (r = −0.724; P < .001) but was not accounted for in the BSA method. Patients with larger livers were relatively underdosed, and patients with smaller livers were relatively overdosed. Patients who received D_WL > 50 Gy experienced more toxicity and adverse events (> grade 2 liver toxicity, 46% vs 17%; P < .05) but also responded better to the treatment than patients who received D_WL< 50 Gy (disease control, 88% vs 24%; P < .01).ConclusionsUsing the standard BSA formula, the administered activity did not correlate with D_WL. Based on this short-term follow-up after salvage therapy in patients with late stage metastatic colorectal carcinoma, dose-response and dose-toxicity relationships support using a protocol based on liver volume rather than BSA to prescribe the administered activity.     

Prospective,Randomized Study of Coil Embolization versus Surefire Infusion System during Yttrium-90 Radioembolization with Resin Microspheres

PurposeTo compare standard coil embolization versus the use of an antireflux microcatheter (ARM) in patients undergoing planning angiography before selective internal radiation therapy (SIRT).Materials and MethodsA prospective, single-center trial was performed in which 30 patients were randomly assigned to undergo SIRT with coil embolization or the use of an ARM. The coil group underwent detachable coil embolization of nontarget vessels, and the ARM group underwent infusion of macroaggregated albumin with use of an ARM system, without coil embolization. Single-photon emission computed tomography (CT)/CT was then performed to assess for nontarget distribution. The primary endpoint was fluoroscopy time during planning angiography. Secondary endpoints included deployment time, total procedure time, radiation dose–area product, contrast agent used, and adverse events. Endpoints were evaluated during planning angiography and SIRT.ResultsOver a 9-month period, 30 consecutive patients were randomized at a 1:1 ratio between coil embolization and ARM groups. Technical success rates were 100% in both groups. Mean fluoroscopy time was significantly reduced in the ARM group versus the coil embolization group (1.8 min [range, 0.4–4.9 min] vs 6.0 min [range, 1.9–15.7 min]; P = .002). The planning procedure time (P < .001), deployment time (P < .001), dose–area product (P = .04), and amount of contrast agent used (P < .001) were also significantly less in the ARM group than in the coil embolization group. No nontarget distribution was detected in either group. There was no difference between groups in dose delivered on the day of SIRT (P = .71). There were no major or minor adverse events at 30 days.ConclusionsThe use of an ARM during planning angiography can significantly reduce fluoroscopy time, procedure time, and radiation dose.     

Radiation Emission from Patients Treated with Holmium-166 Radioembolization

PurposeTo assess the radiation exposure to individuals coming from patients after treatment with holmium-166 (¹⁶⁶Ho) microspheres.Materials and MethodsHolmium-166 radioembolization (RE) with escalating whole-liver doses of 20 Gy, 40 Gy, 60 Gy, and 80 Gy was administered to 15 patients. Exposure rates (μSv/h) from patients were measured at 1.0 m distance from a lateral and frontal position at 0, 3, 6, 24, and 48 hours after infusion. The total effective dose equivalent (TEDE) to a maximally exposed contact was calculated in accordance with guidelines of the U.S. Nuclear Regulatory Commission (NRC). Results were extrapolated to a whole-liver dose of 60 Gy used in future treatments.ResultsThe median exposure rate at discharge, 48 hours after infusion, measured from a lateral position was 26 μSv/h (range, 7–45 μSv/h). Extrapolated to a whole-liver dose of 60 Gy, none of the exposure rates for the NRC contact scenario, at any time, frontal or lateral, would lead to a TEDE > 5 mSv; all patients may be released directly after treatment. Release after 6 hours is possible without contact restrictions for patients who received up to 7 GBq.ConclusionsThe TEDE to a contact of patients treated with ¹⁶⁶Ho RE would not exceed the NRC limit of 5 mSv. Contact restrictions 6 hours after treatment are unnecessary for infused activities < 7 GBq.