Radiographic Response to Yttrium-90 Radioembolization in Anterior Versus Posterior Liver Segments

The purpose of our study was to determine if preferential radiographic tumor response occurs in tumors located in posterior versus anterior liver segments following radioembolization with yttrium-90 glass microspheres. One hundred thirty-seven patients with chemorefractory liver metastases of various primaries were treated with yttrium-90 glass microspheres. Of these, a subset analysis was performed on 89 patients who underwent 101 whole-right-lobe infusions to liver segments V, VI, VII, and VIII. Pre- and posttreatment imaging included either triphasic contrast material-enhanced CT or gadolinium-enhanced MRI. Responses to treatment were compared in anterior versus posterior right lobe lesions using both RECIST and WHO criteria. Statistical comparative studies were conducted in 42 patients with both anterior and posterior segment lesions using the paired-sample t-test. Pearson correlation was used to determine the relationship between pretreatment tumor size and posttreatment tumor response. Median administered activity, delivered radiation dose, and treatment volume were 2.3 GBq, 118.2 Gy, and 1,072 cm³, respectively. Differences between the pretreatment tumor size of anterior and posterior liver segments were not statistically significant (p = 0.7981). Differences in tumor response between anterior and posterior liver segments were not statistically significant using WHO criteria (p = 0.8557). A statistically significant correlation did not exist between pretreatment tumor size and posttreatment tumor response (r = 0.0554, p = 0.4434). On imaging follow-up using WHO criteria, for anterior and posterior regions of the liver, (1) response rates were 50% (PR = 50%) and 45% (CR = 9%, PR = 36%), and (2) mean changes in tumor size were −41% and −40%. In conclusion, this study did not find evidence of preferential radiographic tumor response in posterior versus anterior liver segments treated with yttrium-90 glass microspheres. Disclosure: R.S. is a consultant for MDS Nordion and has disclosed a potential conflict of interest. None of the other authors have disclosed a conflict. The data were controlled by all authors. No industry support for this study was provided.     

Radioembolization with Yttrium-90 resin microspheres in treatment of HCC with or without PVT: Initial Egyptian experience

Background/Aim

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver. Radioembolization with yttrium-90 (Y-90) microspheres is a new concept in radiation therapy for HCC. The aim of this study is to evaluate efficacy, side effects, and future direction of Y-90 therapy, using TheraSphere®, in patients with HCC with or without PVT.

Patients and methods

Forty patients were presented by hepatocellular carcinoma most of them with portal vein thrombosis and were treated with Y-90 resin microspheres (SIR-TeX®).

Results

At one month after treatment the overall response (complete or partial response) was exhibited by 9% of patients, stable disease exhibited by 80% of patients, progressive disease seen in 11% of patients.

Conclusion

Radioembolization with Y-90 resin microspheres offers a favorable risk/benefit profile for patients presenting with locally advanced unresectable HCC with or without PVT and good liver function.     

Radioembolization with 90Y Microspheres: Angiographic and Technical Considerations

The anatomy of the mesenteric system and the hepatic arterial bed has been demonstrated to have a high degree of variation. This is important when considering pre-surgical planning, catheterization, and trans-arterial hepatic therapies. Although anatomical variants have been well described, the characterization and understanding of regional hepatic perfusion in the context of radioembolization have not been studied with great depth. The purpose of this review is to provide a thorough discussion and detailed presentation of the angiographic and technical aspects of radioembolization. Normal vascular anatomy, commonly encountered variants, and factors involved in changes to regional perfusion in the presence of liver tumors are discussed. Furthermore, the principles described here apply to all liver-directed transarterial therapies. R.S. and J.-F.G. are consultants for MDS Nordion. R.M., D.L., L.B., and J.I.B. are proctors for Sirtex Medical. A.S.K. has received honoraria from MDS Nordion and Sirtex Medical. This work was not funded.     

Radiation doses of yttrium-90 citrate and yttrium-90 EDTMP as determined via analogous yttrium-86 complexes and positron emission tomography

Yttrium-90 is used for palliative therapy for the treatment of skeletal metastases, but because it is a pure - emitter, data on the pharmacokinetics and radiation doses to metastases and unaffected organs are lacking. To obtain such data, the present study employed yttrium-86 as a substitute for⁹⁰Y, with detection by positron emission tomography (PET). The study compared the properties of two different⁸⁶Y complexes —⁸⁶y-citrate and⁸⁶Y -ethylene diamine tetramethylene phosphonate (EDTMP) — in ten patients with prostatic cancer who had developed multiple bone metastases (the ten patients being divided into two groups of five). Early dynamics were measured up to 1 h post injection (p.i.) over the liver region, followed by subsequent whole-body PET scans up to 3 days p.i. Absolute uptake data were determined for normal bone, bone metastases, liver and kidney. Radiation doses were calculated according to the MIRD recommendations. Based on the pharmacokinetic measurements of the distribution of the⁸⁶Y complexes, it was possible to calculate radiation doses for the bone metastases and the red bone marrow delivered by complexes containing⁹⁰Y. In 1 cm³ of bone metastasis, doses of 26±11 mGy/MBq and 18±2 mGy/MBq were determined per MBq of injected⁹⁰Y- citrate and⁹⁰Y- EDTMP, respectively. The doses to the bone marrow were 2.5±0.4 mGy/MBq for⁹⁰Y- citrate and 1.8±0.6 mGy/MBq for⁹⁰Y-EDTMP.⁸⁶Y and PET provide quantitative information applicable to the clinical use of⁹⁰Y. This method may also be useful for the design of other⁹⁰Y radiopharmaceuticals and for planning radiotherapy dosages.     

Treatment of Unresectable Primary and Metastatic Liver Cancer with Yttrium-90 Microspheres (TheraSphere®): Assessment of Hepatic Arterial Embolization

In Canada and Europe, yttrium-90 microspheres (TheraSphere); MDS Nordion, Ottawa, Canada) are a primary treatment option for primary and secondary hepatic malignancies. We present data from 30 patients with hepatocellular carcinoma (HCC) and metastatic liver disease treated with TheraSphere from a single academic institution to evaluate the angiographically evident embolization that follows treatment. Seven interventional radiologists from one treatment center compared pretreatment and posttreatment angiograms. The reviewers were blinded to the timing of the studies. The incidence of postembolization syndrome (PES) was determined as well as objective tumor response rates by the World Health Organization (WHO), Response Evaluation Criteria in Solid Tumors (RECIST), and European Association for the Study of the Liver (EASL) criteria. There were 420 independent angiographic observations that were assessed using the chi-squared statistic. The pretreatment and posttreatment angiograms could not be correctly identified on average more than 43% of the time (p = 0.0004). The postprocedure arterial patency rate was 100%. The objective tumor response rates for all patients were 24%, 31%, and 72% for WHO, RECIST, and EASL criteria, respectively. All of the patients tolerated the procedure without complications and were treated on an outpatient basis, and four patients had evidence of PES. This treatment method does not result in macroscopic embolization of the hepatic arteries, thereby maintaining hepatic tissue perfusion. These data support the principle that the favorable response rates reported with TheraSphere are likely due to radiation and microscopic embolization rather than flow-related macroscopic embolization and ischemia.     

ACR–ABS–ACNM–ASTRO–SIR–SNMMI practice parameter for selective internal radiation therapy or radioembolization for treatment of liver malignancies

PurposeThe American College of Radiology (ACR), American Brachytherapy Society (ABS), American College of Nuclear Medicine (ACNM), American Society for Radiation Oncology (ASTRO), Society of Interventional Radiology (SIR), and Society of Nuclear Medicine and Molecular Imaging (SNMMI) have jointly developed a practice parameter on selective internal radiation therapy (SIRT) or radioembolization for treatment of liver malignancies. Radioembolization is the embolization of the hepatic arterial supply of hepatic primary tumors or metastases with a microsphere yttrium-90 brachytherapy device.Materials and MethodsThe ACR -ABS -ACNM -ASTRO -SIR -SNMMI practice parameter for SIRT or radioembolization for treatment of liver malignancies was revised in accordance with the process described on the ACR website (https://www.acr.org/ClinicalResources/Practice-Parameters-and-Technical-Standards) by the Committee on Practice Parameters—Interventional and Cardiovascular Radiology of the ACR Commission on Interventional and Cardiovascular, Committee on Practice Parameters and Technical Standards—Nuclear Medicine and Molecular Imaging of the ACR Commission on Nuclear Medicine and Molecular Imaging and the Committee on Practice Parameters—Radiation Oncology of the ACR Commission on Radiation Oncology in collaboration with ABS, ACNM, ASTRO, SIR, and SNMMI.ResultsThis practice parameter is developed to serve as a tool in the appropriate application of radioembolization in the care of patients with conditions where indicated. It addresses clinical implementation of radioembolization including personnel qualifications, quality assurance standards, indications, and suggested documentation.ConclusionsThis practice parameter is a tool to guide clinical use of radioembolization. It focuses on the best practices and principles to consider when using radioemboliozation effectively. The clinical benefit and medical necessity of the treatment should be tailored to each individual patient.     

Clinical practice in radioembolization of hepatic malignancies: a survey among interventional centers in Europe

Objectives

A survey was conducted to give an overview about the practice of radioembolization in malignant liver tumors by European centers.

Methods

A questionnaire of 23 questions about the interventional center, preinterventional patient evaluation, the radioembolization procedure and aftercare were sent to 45 European centers.

Results

The response rate was 62.2% (28/45). The centers performed 1000 (median = 26) radioembolizations in 2009 and 1292 (median = 40) in 2010. Most centers perform preinterventional evaluation and radioembolization on an inpatient basis. An arterioportal shunt not amendable to preinterventional embolization is considered a contraindication. During preinterventional angiography, the gastroduodenal artery is embolized by 71%, the right gastric artery by 59%, and the cystic artery by 41%. In case of bilobar disease, yttrium-90 microspheres are infused into the common hepatic artery (14%) or separately into left and right hepatic artery (86%). 33% prefer a time interval between right and left liver lobe radioembolization to prevent radiation induced liver disease. 43% of the respondents do not prescribe prophylactic medication after radioembolization. In case of iatrogenic manipulation to the biliary duct system most centers perform radioembolization with prophylactic antibiotics.

Conclusions

Despite standardization of the procedure, there are some differences in how radioembolization of liver tumors is performed in Europe.     

Usefulness of Bremsstrahlung Images after Intra-arterial Y-90 Resin Microphere Radioembolization for Hepatic Tumors

Purpose

Y-90 resin microsphere radioembolization is used to treat inoperable hepatic tumors. After injection of Y-90 resin microsphere, the only method to visualize the distribution of Y-90 is the scintigraphic imaging of bremsstrahlung radiation. The purpose of this study was to evaluate the characteristics and usefulness of bremsstrahlung imaging in Y-90 resin microsphere treatment.

Methods

Twenty patients (22 administrations) underwent intra-arterial Y-90 resin microsphere treatment. For pre-treatment planning, images of Tc-99m albumin macroaggregate (MAA) arterial injection and hepatic contrast angiography were obtained. Post-treatment bremsstrahlung images were taken and compared with pre-treatment images. The extrahepatic activity was evaluated on bremsstrahlung images. To correlate the size and vascularity of the tumors with tumor visualization on bremsstrahlung images, the individual tumors were grouped according to visualization on each image and compared with one another by size and tumor-to-normal ratio.

Results

All post-therapeutic bremsstrahlung images showed similar contours of the liver with pre-treatment angiography. No extrahepatic activity was seen in all cases. The visualized tumors on bremsstrahlung images were significantly larger than the non-visualized tumors. Tumor-to-normal ratios of the visualized tumors on bremsstrahlung images were significantly higher than those of the non-visualized tumors.

Conclusions

Bremsstrahlung images after intra-arterial Y-90 resin microsphere treatment are useful in evaluating the intrahepatic distribution of radioisotope and detecting possible extrahepatic activity.     

Palonosetron—A Single-Dose Antiemetic Adjunct for Hepatic Artery Radioembolization: A Feasibility Study

Nausea and vomiting may occur in a significant minority of patients following hepatic artery embolization with yttrium-90 spheres (K. T. Sato et al. Radiology 247:507–515, 2008). This encumbers human and economic resources and undercuts the assertion that it is as a well-tolerated outpatient treatment. A single intravenous dose of palonosetron HCl was administered before hepatic artery embolization with yttrium-90 spheres to ameliorate posttreatment nausea and vomiting, in 23 consecutive patients. The patients were discharged the day of procedure on oral antiemetics, steroids, and blockers of gastric acid release. All patients had clinical and laboratory evaluation at 2 weeks after the procedure. The data were gathered and reviewed retrospectively. At 2-week follow-up, none reported significant nausea, vomiting, additional antiemetic use, need for parenteral therapy, hospital readmission, or palonosetron-related side effects. All patients recovered from postembolization symptoms within a week after treatment. In conclusion, this retrospective study suggests that single-dose palonosetron is feasible, safe, and effective for acute and delayed nausea and vomiting in this group of patients. The added cost may be offset by benefits.     

Uptake kinetics of the somatostatin receptor ligand [86Y]DOTA-dPhe1-Tyr3-octreotide ([86Y]SMT487) using positron emission tomography in non-human primates and calculation of radiation doses of the 90Y-labelled analogue

[⁹⁰Y]DOTA-dPhe¹-Tyr³-octreotide ([⁹⁰Y]-SMT487) has been suggested as a promising radiotherapeutic agent for somatostatin receptor-expressing tumours. In order to quantify the in vivo parameters of this compound and the radiation doses delivered to healthy organs, the analogue [⁸⁶Y]DOTA-dPhe¹-Tyr³-octreotide was synthesised and its uptake measured in baboons using positron emission tomography (PET). [⁸⁶Y]DOTA-dPhe¹-Tyr³-octreotide was administered at two different peptide concentrations, namely 2 and 100 μg peptide per m² body surface. The latter concentration corresponded to a radiotherapeutic dose. In a third protocol [⁸⁶Y]DOTA-dPhe¹-Tyr³-octreotide was injected in conjunction with a simultaneous infusion of an amino acid solution that was high in l-lysine in order to lower the renal uptake of radioyttrium. Quantitative whole-body PET scans were recorded to measure the uptake kinetics for kidneys, liver, lung and bone. The individual absolute uptake kinetics were used to calculate the radiation doses for [⁹⁰Y]DOTA-dPhe¹-Tyr³-octreotide according to the MIRD recommendations extrapolated to a 70-kg human. The highest radiation dose was received by the kidneys, with 2.1–3.3 mGy per MBq [⁹⁰Y]DOTA-dPhe¹-Tyr³-octreotide injected. For the 100 μg/m² SMT487 protocol with amino acid co-infusion this dose was about 20%–40% lower than for the other two treatment protocols. The liver and the red bone marrow received doses ranging from 0.32 to 0.53 mGy and 0.03 to 0.07 mGy per MBq [⁹⁰Y]DOTA-dPhe¹-Tyr³-octreotide, respectively. The average effective dose equivalent amounted to 0.23–0.32 mSv/MBq. The comparatively low estimated radiation doses to normal organs support the initiation of clinical phase I trials with [⁹⁰Y]DOTA-dPhe¹-Tyr³-octreotide in patients with somatostatin receptor-expressing tumours. Received 26 September and in revised form 18 November 1998     

Can imaging patterns of neuroendocrine hepatic metastases predict response yttruim-90 radioembolotherapy?

AIM:To evaluate the response to treatment in patients with neuroendocrine tumor liver metastases following yttrium-90 ( 90 Y) radioembolotherapy, as a function of image patterns at presentation for 90 Y radioembolotherapy. METHODS: The study cohort consisted of patients with hepatic metastatic neuroendocrine tumors treated with 90 Y at our institution during a two-year time period. Hepatic metastases were evaluated on a pretherapy study assessing relative arterial enhancement compared to liver, lesion size, necrosis of the lesion, and associated tumor burden in the liver. We used six response criteria: Response Evaluation Criteria in Solid Tumors (RECIST) size, World Health Organization (WHO) size, European Association for the Study of the Liver (EASL) necrosis guidelines, Choi size, Choi necrosis and combination of Choi size and necrosis. RESULTS: About 65 lesions in 17 patients met study criteria and formed the cohort. Statistically significant response was found for lesions < 5 cm vs those ≥5 cm with RECIST (P = 0.04), WHO (P = 0.002) and combined Choi criteria (P = 0.02). Hyperenhancing lesions demonstrated greater response only with the Choi size criteria (P = 0.04). Lesions with ≤ 50% necrosis on the pre-scan had statistically significant greater response with the Choi necrosis criteria (P = 0.01). There was no statistical significance for response comparing lesions < 2 cm vs ≥ 2 cm or in comparing the degrees of tumor burden. CONCLUSION: Based on our findings in this study, it is suggested that initial imaging findings, as listed above, are not a good predictor of response to 90 Y radioembolization.     

Right Gastric Artery Embolization Prior to Treatment with Yttrium-90 Microspheres

Purpose Intra-arterial infusion of yttrium-90 microspheres is a form of radiation treatment for unresectable hepatic neoplasms. Misdeposition of particles in the gastroduodenal area such as the right gastric artery (RGA) may occur with serious consequences. We present a series of patients who underwent a detailed vascular study followed by RGA embolization. Special emphasis is placed on anatomic variations and technical considerations. Methods In a 1 year period, 27 patients were treated. Initial vascular evaluation was performed, with careful attention to anatomic variants or extrahepatic arterial supply, especially to the gastroduodenal area. Embolization of such arteries was planned if needed. RGA embolization was performed antegradely from the hepatic artery or retrogradely via the left gastric artery (LGA). Postprocedural follow-up included clinical interview and gastroscopy if necessary. Results RGA embolization was performed in 9 patients presenting with primary (n = 3) or metastatic liver tumors (n = 6). Six patients underwent antegrade RGA embolization and 3 had embolization done retrogradely via the LGA. Retrograde access was chosen for anatomic reasons. None of the patients complained of gastroduodenal symptoms. Conclusion RGA embolization can help minimize the gastroduodenal deposition of radioactive particles. RGA embolization should routinely be carried out. The procedure can be performed, with similar technical success, by both anterograde and retrograde approaches.     

Evaluation of several multiple diglycolamide-functionalized calix[4]arene ligands for the isolation of carrier free 90Y from 90Sr

Several diglycolamide-functionalized calix[4]arenes containing four and eight diglycolamide (DGA) moieties were evaluated for their relative extraction efficiencies towards Y(III) and Sr(II). Ligands containing four DGA units with n-propyl, iso-pentyl, and n-octyl groups at the amidic N atom adjacent to the calix[4]arene skeleton showed efficient extraction of Y(III) from 3 M HNO₃. The extraction of Sr(II) was poor in all cases in the entire acidity range (0.1–6 M HNO₃) studied. The ligands with a hydrogen atom and an n-propyl group at the concerning amidic N atom showed a very high separation efficiency as reflected in separation factor (S.F.=D_Y/D_Sr) values in the range of 10⁵–10⁶. A method was developed for the separation of carrier-free ⁹⁰Y from a ⁹⁰Y-⁹⁰Sr mixture involving consecutive extraction–stripping cycles. The product purity was checked using half-life measurements. Two consecutive cycles of extraction and stripping were found to be sufficient for obtaining pure ⁹⁰Y. The results obtained in the present studies were compared with those obtained previously using analogous ligands such as TODGA (N,N,N',N'-tetraoctyl diglycolamide), T2EHDGA (N,N,N',N'-tetra-2-ethylhexyl diglycolamide), and PC-88A (bis(2-ethylhexyl) phosphonic acid).     

Role of diluent on the separation of Y from Sr by solvent extraction and supported liquid membrane using T2EHDGA as the extractant

The separation behaviour of ⁹⁰Y from ⁹⁰Sr was investigated by diluent variation using solvent extraction and supported liquid membrane techniques employing N,N,N′,N′-tetra-2-ethylhexyldiglycolamide (T2EHDGA) as the extractant. Both D_Y (distribution ratio of Y(III)) and S.F. (separation factor) were found to be high in the solvent extraction studies when chloroform was used as the diluent. Subsequent supported liquid membrane (SLM) studies using PTFE flat sheet membranes containing 0.2 M T2EHDGA in various diluents indicated the trend of Y transport as xylene>hexone>chloroform>carbon tetrachloride>n-dodecane+30% iso-decanol mixture. However, the Sr(II) transport rates were also high with xylene, hexone, and carbon tetrachloride as the diluents which led us to carry out subsequent studies using chloroform and n-dodecane+30% iso-decanol mixture. Acid variation studies in chloroform system indicated an interesting phenomena of increasing Y(III) transport and decreasing Sr(II) transport with increasing acid concentration. Separation of ⁹⁰Y from a mixture of ⁹⁰Sr and ⁹⁰Y was also attempted.     

Three-step radioimmunotherapy with yttrium-90 biotin: dosimetry and pharmacokinetics in cancer patients

. A three-step avidin-biotin approach has been applied as a pretargeting system in radioimmunotherapy (RIT) as an alternative to conventional RIT with directly labelled monoclonal antibodies (MoAbs). Although dosimetric and toxicity studies following conventional RIT have been reported, these aspects have not previously been evaluated in a three-step RIT protocol. This report presents the results of pharmacokinetic and dosimetric studies performed in 24 patients with different tumours. Special consideration was given to the dose delivered to the red marrow and to the haematological toxicity. The possible additive dose to red marrow due to the release of unbound yttrium-90 was investigated. The protocol consisted in the injection of biotinylated MoAbs (first step) followed 1 day later by the combined administration of avidin and streptavidin (second step). After 24 h, biotin radiolabelled with 1.85–2.97 GBq/m² of ⁹⁰Y was injected (third step). Two different chelating agents, DTPA and DOTA, coupled to biotin, were used in these studies. Indium-111 biotin was used as a tracer of ⁹⁰Y to follow the biodistribution during therapy. Serial blood samples and complete urine collection were obtained over 3 days. Whole-body and single-photon emission tomography images were acquired at 1, 16, 24 and 40 h after injection. The sequence of images was used to extrapolate ⁹⁰Y-biotin time-activity curves. Numerical fitting and compartmental modelling were used to calculate the residence time values (τ) for critical organs and tumour, and results were compared; the absorbed doses were estimated using the MIRDOSE3.1 software. The residence times obtained by the numerical and compartmental models showed no relevant differences (<10%); the compartmental model seemed to be more appropriate, giving a more accurate representation of the exchange between organs. The mean value for the τ in blood was 2.0±1.1 h; the mean urinary excretion in the first 24 h was 82.5%±10.8%. Without considering any contribution of free ⁹⁰Y, kidneys, liver, bladder and red marrow mean absorbed doses were 1.62±1.14, 0.27±0.23, 3.61±0.70 and 0.11±0.05 mGy/MBq, respectively; the effective dose was 0.32±0.06 mSv/MBq, while the dose to the tumour ranged from 0.62 to 15.05 mGy/MBq. The amount of free ⁹⁰Y released after the injection proved to be negligible in the case of ⁹⁰Y-DOTA-biotin, but noteworthy in the case of ⁹⁰Y-DTPA-biotin (mean value: 5.6%±2.5% of injected dose), giving an additive dose to red marrow of 0.18±0.08 mGy per MBq of injected ⁹⁰Y-DTPA-biotin. Small fractions of free ⁹⁰Y originating from incomplete radiolabelling can contribute significantly to the red marrow dose (3.26 mGy per MBq of free ⁹⁰Y) and may explain some of the high levels of haematological toxicity observed. These results indicate that pretargeted three-step RIT allows the administraton of high ⁹⁰Y activities capable of delivering a high dose to the tumour and sparing red marrow and other normal organs. Although ⁹⁰Y-biotin clears rapidly from circulation, the use of DOTA-biotin conjugate for a stable chelation of ⁹⁰Y is strongly recommended, considering that small amounts of free ⁹⁰Y contribute significantly in increasing the red marrow dose. Received 6 June and in revised form 19 September 1998     

黑色素瘤脑转移的低场MRI表现

目的 总结黑色素瘤脑转移的低场MRI表现,以提高对该病的认识. 资料与方法 回顾分析8例经手术病理证实的黑色素瘤脑转移患者的MRI表现. 结果 黑色素瘤脑转移患者的MRI表现分为3种:(1)脑内多发大小不等、球状、结节状病灶,T1WI高信号,T2WI上为低信号,灶周水肿明显,增强扫描病灶呈均一高信号,共4例;(2)肿瘤内可有出血而致信号不均匀,增强后多呈不规则、花环状强化影,共3例;(3)在前两种表现基础上合并脑膜转移,共1例. 结论 黑色素瘤脑转移的瘤体易出血和富含黑色素颗粒这两个特征,决定其MRI表现的特性.     

Cherenkov counting of yttrium-90 in the dry state; correlations with phosphorus-32 Cherenkov counting data

We present data that illustrate some advantages of Cherenkov counting for the radioassay of ⁹⁰Y in the dry state and provide recommendations concerning sample counting geometry. Slightly higher detection efficiencies and figures-of-merit were obtained when counting ⁹⁰Y in the dry state in polyethylene plastic counting vials compared to the counting of ⁹⁰Y in 20 ml of water in borosilicate glass vials. The effects of polyethylene plastic counting vials and sample counting geometry are compared to similar data obtained in the Cherenkov counting of ³²P. Data are presented to interpret the effects of polyethylene plastic and borosilicate glass on Cherenkov counting efficiency and background counts. Applications of the Cherenkov counting of ⁹⁰Y and ³²P in the dry state in the biological and radiopharmaceutical sciences are foreseen as well as applications in the analysis of ⁹⁰Sr(⁹⁰Y) and ³²P in health physics and environmental monitoring.     

Yttrium-90 Selective Internal Radiation Therapy with Glass Microspheres for Hepatocellular Carcinoma: Current and Updated Literature Review

Hepatocellular carcinoma is the most common primary liver cancer and it represents the majority of cancer-related deaths in the world. More than 70% of patients present at an advanced stage, beyond potentially curative options. Ytrrium-90 selective internal radiation therapy (Y90-SIRT) with glass microspheres is rapidly gaining acceptance as a potential therapy for intermediate and advanced stage primary hepatocellular carcinoma and liver metastases. The technique involves delivery of Y90 infused glass microspheres via the hepatic arterial blood flow to the appropriate tumor. The liver tumor receives a highly concentrated radiation dose while sparing the healthy liver parenchyma due to its preferential blood supply from portal venous blood. There are two commercially available devices: TheraSphere® and SIR-Spheres®. Although, Y90-SIRT with glass microspheres improves median survival in patients with intermediate and advanced hepatocellular carcinoma and has the potential to downstage hepatocellular carcinoma so that the selected candidates meet the transplantable criteria, it has not gained widespread acceptance due to the lack of large randomized controlled trials. Currently, there are various clinical trials investigating the use of Y90-SIRT with glass microspheres for treatment of hepatocellular carcinoma and the outcomes of these trials may result in the incorporation of Y90-SIRT with glass microspheres into the treatment guidelines as a standard therapy option for patients with intermediate and advanced stage hepatocellular carcinoma.     

Semi-Quantitative Analysis of Post-Transarterial Radioembolization 90Y Microsphere Positron Emission Tomography Combined with Computed Tomography (PET/CT) Images in Advanced Liver Malignancy: Comparison With 99mTc Macroaggregated Albumin (MAA) Single Photon Emission Computed Tomography (SPECT)

Objectives

The purpose of this study is to evaluate the correlation between pretreatment planning technetium-99m (^99mTc) macroaggregated albumin (MAA) SPECT images and posttreatment transarterial radioembolization (TARE) yttirum-90 (⁹⁰Y) PET/CT images by comparing the ratios of tumor-to-normal liver counts.

Methods

Fifty-two patients with advanced hepatic malignancy who underwent ⁹⁰Y microsphere radioembolization from January 2010 to December 2012 were retrospectively reviewed. Patients had undergone ^99mTc MAA intraarterial injection SPECT for a pretreatment evaluation of microsphere distribution and therapy planning. After the administration of ⁹⁰Y microspheres, the patients underwent posttreatment ⁹⁰Y PET/CT within 24 h. For semiquantitative analysis, the tumor-to-normal uptake ratios in ⁹⁰Y PET/CT (TNR-yp) and ^99mTc MAA SPECT (TNR-ms) as well as the tumor volumes measured in angiographic CT were obtained and analyzed. The relationship of TNR-yp and TNR-ms was evaluated by Spearman''s rank correlation and Wilcoxon''s matched pairs test.

Results

In a total of 79 lesions of 52 patients, the distribution of microspheres was well demonstrated in both the SPECT and PET/CT images. A good correlation was observed of between TNR-ms and TNR-yp (rho value = 0.648, p < 0.001). The TNR-yp (median 2.78, interquartile range 2.43) tend to show significantly higher values than TNR-ms (median 2.49, interquartile range of 1.55) (p = 0.012). The TNR-yp showed weak correlation with tumor volume (rho = 0.230, p = 0.041).

Conclusions

The ^99mTc MAA SPECT showed a good correlation with ⁹⁰Y PET/CT in TNR values, suggesting that ^99mTc MAA can be used as an adequate pretreatment evaluation method. However, the ^99mTc MAA SPECT image consistently shows lower TNR values compared to ⁹⁰Y PET/CT, which means the possibility of underestimation of tumorous uptake in the partition dosimetry model using ^99mTc MAA SPECT. Considering that ^99mTc MAA is the only clinically available surrogate marker for distribution of microsphere, we recommend measurement of tumorous uptake using ⁹⁰Y PET/CT should be included routinely in the posttherapeutic evaluation.