Dataset Information

Inter-observer variability of 90Y PET/CT dosimetry in hepatocellular carcinoma after glass microspheres transarterial radioembolization.

ABSTRACT: INTRODUCTION:Strong correlation has been demonstrated between tumor dose and response and between healthy liver dose and side effects. Individualized dosimetry is increasingly recommended in the current clinical routine. However, hepatic and tumor segmentations could be complex in some cases. The aim of this study is to assess the reproducibility of the tumoral and non-tumoral liver dosimetry in selective internal radiation therapy (SIRT). MATERIAL AND METHODS:Twenty-three patients with hepatocellular carcinoma (HCC) who underwent SIRT with glass microspheres were retrospectively included in the study. Tumor (TV) and total liver volumes (TLV), and mean absorbed doses in tumoral liver (TD) and non-tumoral liver (THLD) were determined on the 90Y PET/CT studies using Simplicit90YTM software, by three independent observers. Dosimetry datasets were obtained by a medical physicist helped by a nuclear medicine (NM) physician with 10?years of experience (A), by a NM physician with 4-year experience (B), and by a resident who first performed 10 dosimetry assessments as a training (C). Inter-observer agreement was evaluated using intra-class correlation coefficients (ICC), coefficients of variation (CV), Bland-Altman plots, and reproducibility coefficient (RDC). RESULTS:A strong agreement was observed between all three readers for estimating TLV (ICC 0.98) and THLD (ICC 0.97). Agreement was lower for TV delineation (ICC 0.94) and particularly for TD (ICC 0.73), especially for the highest values. Regarding TD, the CV (%) was 26.5, 26.9, and 20.2 between observers A and B, A and C, and B and C, respectively, and the RDC was 1.5. Regarding THLD, it was 8.5, 12.7, and 9.4, and the RDC was 1.3. CONCLUSION:Using a standardized methodology, and regardless of the different experiences of the observers, the estimation of THLD is highly reproducible. Although the reproducibility of the assessment of tumor irradiation is overall quite high, large variations may be observed in a limited number of patients.

SUBMITTER: Meyers N

PROVIDER: S-EPMC7218042 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Inter-observer variability of <sup>90</sup>Y PET/CT dosimetry in hepatocellular carcinoma after glass microspheres transarterial radioembolization.

Meyers Nicolas N Jadoul Alexandre A Bernard Claire C Delwaide Jean J Lamproye Anne A Detry Olivier O Honoré Pierre P Gerard Laurent L Hustinx Roland R

EJNMMI physics 20200512 1

<h4>Introduction</h4>Strong correlation has been demonstrated between tumor dose and response and between healthy liver dose and side effects. Individualized dosimetry is increasingly recommended in the current clinical routine. However, hepatic and tumor segmentations could be complex in some cases. The aim of this study is to assess the reproducibility of the tumoral and non-tumoral liver dosimetry in selective internal radiation therapy (SIRT).<h4>Material and methods</h4>Twenty-three patient ...[more]

PMID: 32399636

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Project description:Transarterial radioembolization (TARE) effectively treats unresectable primary and metastatic liver tumors through intra-arterial injection of Yttrium-90 (90 Y) beta particle emitting microspheres which implant around the tumor. Current dosimetry models are highly simplistic and there is a large need for an image-based dosimetry post-TARE, which would improve treatment safety and efficacy. Current post-TARE imaging is 90 Y bremsstrahlung SPECT/CT and we study the use of these images for dosimetry. Retrospective image review of ten patients having a Philips HealthcareTM SPECT/CT following TARE SIR-Spheres® implantation. Emission series with attenuation correction were resampled to 3 mm resolution and used to create image-based dose distributions. Dose distributions and analysis were performed in MIM Software SurePlanTM utilizing SurePlanTM Local Deposition Method (LDM) and a dose convolution method (WFBH). We sought to implement a patient-specific background subtraction prior to dose calculation to make these noisy bremsstrahlung SPECT images suitable for post-TARE dosimetry. On average the percentage of mean background counts to maximum count in the image across all patients was 9.4 ± 4.9% (maximum = 7.6%, minimum = 2.3%). Absolute dose increased and profile line width decreased as background subtraction value increased. The average value of the LDM and WFBH dose methods was statistically the same. As background subtraction value increased, the DVH curves become unrealistic and distorted. Background subtraction on bremsstrahlung SPECT image has a large effect on post-TARE dosimetry. The background contour defined provides a systematic estimate to the activity background that accounts for the scanner and patient conditions at the time of the image study and is easily implemented using commercially available software. Using the mean count in the background contour as a subtraction across the entire image gave the most realistic dose distributions. This methodology is independent of microsphere and software manufacturer allowing for use with any available products or tools.

Project description:BackgroundCoincidence imaging of low-abundance yttrium-90 (90Y) internal pair production by positron emission tomography with integrated computed tomography (PET/CT) achieves high-resolution imaging of post-radioembolization microsphere biodistribution. Part 2 analyzes tumor and non-target tissue dose-response by 90Y PET quantification and evaluates the accuracy of tumor 99mTc macroaggregated albumin (MAA) single-photon emission computed tomography with integrated CT (SPECT/CT) predictive dosimetry.MethodsRetrospective dose quantification of 90Y resin microspheres was performed on the same 23-patient data set in part 1. Phantom studies were performed to assure quantitative accuracy of our time-of-flight lutetium-yttrium-oxyorthosilicate system. Dose-responses were analyzed using 90Y dose-volume histograms (DVHs) by PET voxel dosimetry or mean absorbed doses by Medical Internal Radiation Dose macrodosimetry, correlated to follow-up imaging or clinical findings. Intended tumor mean doses by predictive dosimetry were compared to doses by 90Y PET.ResultsPhantom studies demonstrated near-perfect detector linearity and high tumor quantitative accuracy. For hepatocellular carcinomas, complete responses were generally achieved at D70 > 100 Gy (D70, minimum dose to 70% tumor volume), whereas incomplete responses were generally at D70 < 100 Gy; smaller tumors (<80 cm3) achieved D70 > 100 Gy more easily than larger tumors. There was complete response in a cholangiocarcinoma at D70 90 Gy and partial response in an adrenal gastrointestinal stromal tumor metastasis at D70 53 Gy. In two patients, a mean dose of 18 Gy to the stomach was asymptomatic, 49 Gy caused gastritis, 65 Gy caused ulceration, and 53 Gy caused duodenitis. In one patient, a bilateral kidney mean dose of 9 Gy (V20 8%) did not cause clinically relevant nephrotoxicity. Under near-ideal dosimetric conditions, there was excellent correlation between intended tumor mean doses by predictive dosimetry and those by 90Y PET, with a low median relative error of +3.8% (95% confidence interval, -1.2% to +13.2%).ConclusionsTumor and non-target tissue absorbed dose quantification by 90Y PET is accurate and yields radiobiologically meaningful dose-response information to guide adjuvant or mitigative action. Tumor 99mTc MAA SPECT/CT predictive dosimetry is feasible. 90Y DVHs may guide future techniques in predictive dosimetry.

Project description:PurposeTransarterial radioembolization (TARE) is a treatment for liver tumours based on injection of radioactive microspheres in the hepatic arterial system. It is crucial to achieve a maximum tumour dose for an optimal treatment response, while minimizing healthy liver dose to prevent toxicity. There is, however, no intraprocedural feedback on the dose distribution, as nuclear imaging can only be performed after treatment. As holmium-166 (166Ho) microspheres can be quantified with MRI, we investigate the feasibility and safety of performing 166Ho TARE within an MRI scanner and explore the potential of intraprocedural MRI-based dosimetry.MethodsSix patients were treated with 166Ho TARE in a hybrid operating room. Per injection position, a microcatheter was placed under angiography guidance, after which patients were transported to an adjacent 3-T MRI system. After MRI confirmation of unchanged catheter location, 166Ho microspheres were injected in four fractions, consisting of 10%, 30%, 30% and 30% of the planned activity, alternated with holmium-sensitive MRI acquisition to assess the microsphere distribution. After the procedures, MRI-based dose maps were calculated from each intraprocedural image series using a dedicated dosimetry software package for 166Ho TARE.ResultsAdministration of 166Ho microspheres within the MRI scanner was feasible in 9/11 (82%) injection positions. Intraprocedural holmium-sensitive MRI allowed for tumour dosimetry in 18/19 (95%) of treated tumours. Two CTCAE grade 3-4 toxicities were observed, and no adverse events were attributed to treatment in the MRI. Towards the last fraction, 4/18 tumours exhibited signs of saturation, while in 14/18 tumours, the microsphere uptake patterns did not deviate from the linear trend.ConclusionThis study demonstrated feasibility and preliminary safety of a first in-human application of TARE within a clinical MRI system. Intraprocedural MRI-based dosimetry enabled dynamic insight in the microsphere distribution during TARE. This proof of concept yields unique possibilities to better understand microsphere distribution in vivo and to potentially optimize treatment efficacy through treatment personalization.RegistrationClinicaltrials.gov, identifier NCT04269499, registered on February 13, 2020 (retrospectively registered).

Dataset Information

Inter-observer variability of 90Y PET/CT dosimetry in hepatocellular carcinoma after glass microspheres transarterial radioembolization.

Publications

Inter-observer variability of <sup>90</sup>Y PET/CT dosimetry in hepatocellular carcinoma after glass microspheres transarterial radioembolization.

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