Quantitative comparison of pre-therapy 99mTc-macroaggregated albumin SPECT/CT and post-therapy PET/MR studies of patients who have received intra-arterial radioembolization therapy with 90Y microspheres

Voxel-based dosimetry with integrated Y-90 PET/MRI and prediction of response of primary and metastatic liver tumors to radioembolization with Y-90 glass microspheres

PURPOSE

In this study, we aimed to evaluate the response of the primary and metastatic liver tumors to radioembolization with 90Y glass microspheres and investigate its correlations with dosimetric variables calculated with 90Y PET/MRI.

METHODS

In this ambispective study, 44 patients treated with 90Y glass microspheres and imaged with 90Y PET/MRI were included for analysis. Dosimetric analysis was performed for every perfused lesion using dose-volume histograms. Response was assessed by comparing pre-treatment and follow-up total lesion glycolysis (TLG) values derived from 18F-FDG PET imaging. The relationship between ΔTLG and log-transformed dosimetric variables was analyzed with linear mixed effects regression models. ROC analyses were performed to compare discriminatory power of the variables in predicting response and complete response.

RESULTS

Regression and ROC analyses demonstrated that mean tumor dose and almost all D values were statistically significant predictors of treatment response and complete treatment response. Specifically, D60, D70 and D80 values exhibited significantly higher discriminatory power for predicting treatment response compared to the mean dose (Dmean) delivered to tumor. High specificity cut-off values to predict response were determined as 160.75 Gy for Dmean, 95.50 Gy for D60, 89 Gy for D70, and 59.50 Gy for D80. Similarly, high-specificity cut-off values to predict complete response were 262.75 Gy for Dmean, 173 Gy for D70, 140.5 Gy for D80, and 100 Gy for D90.

CONCLUSION

In this study, we demonstrated that voxel-based dosimetry with post-treatment 90Y PET/MRI can predict response to treatment. D60, D70 and D80 variables also did have greater discriminatory power compared to Dmean in prediction of response. In addition, we present high-specificity cut-offs to predict response (CR + PR) and complete response (CR) for both Dmean and several D variables derived from dose-volume histograms.

Voxel-S-Value based 3D treatment planning methods for Y-90 microspheres radioembolization based on Tc-99m-macroaggregated albumin SPECT/CT

Partition model (PM) for Y-90 microsphere radioembolization is limited in providing 3D dosimetrics. Voxel-S-Values (VSV) method has good agreement with Monte Carlo (MC) simulations for 3D absorbed dose conversion. We propose a new VSV method and compare its performance along with PM, MC and other VSV methods for Y-90 RE treatment planning based on Tc-99m MAA SPECT/CT. Twenty Tc-99m-MAA SPECT/CT patient data are retrospectively analyzed. Seven VSV methods are implemented: (1) local energy deposition; (2) liver kernel; (3) liver kernel and lung kernel; (4) liver kernel with density correction (LiKD); (5) liver kernel with center voxel scaling (LiCK); (6) liver kernel and lung kernel with density correction (LiLuKD); (7) proposed liver kernel with center voxel scaling and lung kernel with density correction (LiCKLuKD). Mean absorbed dose and maximum injected activity (MIA) obtained by PM and VSV are evaluated against MC results, and 3D dosimetrics generated by VSV are compared with MC. LiKD, LiCK, LiLuKD and LiCKLuKD have the smallest deviation in normal liver and tumors. LiLuKD and LiCKLuKD have the best performance in lungs. MIAs are similar by all methods. LiCKLuKD could provide MIA consistent with PM, and precise 3D dosimetrics for Y-90 RE treatment planning.

Dosimetric impact of 3D motion-compensated SPECT reconstruction for SIRT planning

BACKGROUND

In selective internal radiation therapy, ^99mTc SPECT images are used to optimize patient treatment planning, but they are affected by respiratory motion. In this study, we evaluated on patient data the dosimetric impact of motion-compensated SPECT reconstruction on several volumes of interest (VOI), on the tumor-to-normal liver (TN) ratio and on the activity to be injected.

METHODS

Twenty-nine patients with liver cancer or hepatic metastases treated by radioembolization were included in this study. The biodistribution of ⁹⁰Y is assumed to be the same as that of ^99mTc when predictive dosimetry is implemented. A total of 31 ^99mTc SPECT images were acquired and reconstructed with two methods: conventional OSEM (3D) and motion-compensated OSEM (3Dcomp). Seven VOI (liver, lungs, tumors, perfused liver, hepatic reserve, healthy perfused liver and healthy liver) were delineated on the CT or obtained by thresholding SPECT images followed by Boolean operations. Absorbed doses were calculated for each reconstruction using Monte Carlo simulations. Percentages of dose difference (PDD) between 3Dcomp and 3D reconstructions were estimated as well as the relative differences for TN ratio and activities to be injected. The amplitude of movement was determined with local rigid registration of the liver between the 3Dcomp reconstructions of the extreme phases of breathing.

RESULTS

The mean amplitude of the liver was 9.5 ± 2.7 mm. Medians of PDD were closed to zero for all VOI except for lungs (6.4%) which means that the motion compensation overestimates the absorbed dose to the lungs compared to the 3D reconstruction. The smallest lesions had higher PDD than the largest ones. Between 3D and 3Dcomp reconstructions, means of differences in lung dose and TN ratio were not statistically significant, but in some cases these differences exceed 1 Gy (4/31) and 8% (2/31). The absolute differences in activity were on average 3.1% ± 5.1% and can reach 22.8%.

CONCLUSION

The correction of respiratory motion mainly impacts the lung and tumor doses but only for some patients. The largest dose differences are observed for the smallest lesions.

Radioembolization, Principles and indications

Radioembolization is the selective application of radionuclide-loaded microspheres into liver arteries for the therapy of liver tumours and metastases. In this review, we focused on therapy planning and dosimetry, as well as the main indications of 90Y-glass and resin microspheres and 166Ho-microspheres.

Magnetic Resonance Imaging and Serum AFP-L3 and GP-73 in the Diagnosis of Primary Liver Cancer

Objective

To investigate the combined application value of magnetic resonance imaging (MRI) combined with serum alpha-fetoprotein (AFP)-L3 and Golgi protein (GP)-73 in the diagnosis of primary liver cancer.

Methods

The data of 200 patients with suspected liver cancer admitted to our hospital from February 2020 to February 2021 were retrospectively analyzed, and they were randomly divided into an experimental group and a control group, with 100 cases in each group. The experimental group received a combined detection of MRI with serum AFP-L3 and GP-73, and the control group adopted traditional diagnostic methods (spiral computed tomography and serum AFP). The diagnostic yields of the two groups were compared. Surgical resection was performed after the diagnosis of primary liver cancer, and the correlation between the efficacy and combined detection of MRI with serum AFP-L3 and GP-73 levels was analyzed.

Results

The two groups presented comparable general information (P >0.05). The surgical results showed 160 cases of primary liver cancer, including 75 cases in the experimental group and 85 cases in the control group, and 40 cases of benign liver lesions. The diagnostic accuracy of the experimental group (73/75, 95%) was significantly higher than that of the control group (76/85, 86%) (P < 0.05). The serum levels of AFP-L3, GP-73, and AFP in patients with primary liver cancer were remarkably decreased after surgery (P < 0.001). The preoperative and postoperative AFP-L3, GP-73, and AFP levels of patients with primary liver cancer were significantly higher than those of patients with benign liver lesions. The AUC (95% CI) for the combined detection of MRI and serum AFP-L3 and GP-73 levels in patients with surgically confirmed primary liver cancer was 0.747 (0.619-0.874).

Conclusion

MRI combined with serum AFP-L3 and GP-73 presents favorable diagnostic efficiency in the diagnosis of primary liver cancer, which is worthy of clinical application.

Antireflux catheter improves tumor targeting in liver radioembolization with resin microspheres

PURPOSE

We aimed to determine whether antireflux (ARC) catheter may result in better tumor targeting in liver radioembolization using 90Y-resin microspheres.

METHODS

Patients treated with resin microspheres for hepatocellular carcinoma (HCC) and secondary liver malignancies were retrospectively analyzed. All patients underwent a 99mTc-macroaggregated albumin (99mTc-MAA) single photon emission computed tomography (SPECT) following the planning arteriography with a conventional end-hole catheter. For 90Y-microspheres injection, two groups were defined depending on the type of catheter used: an ARC group (n=38) and a control group treated with a conventional end-hole catheter (n=23). 90Y positron emission tomography computed tomography (PET/CT) was performed after the therapeutic arteriography. The choice of the catheter was not randomized, but left to the choice of the interventional radiologist. 99mTc-MAA SPECT and 90Y PET/CT were co-registered with the baseline imaging to determine a tumor to normal liver ratio (T/NL[MAA or 90Y]) and tumor dose (TD[MAA or 90Y]) for the planning and therapy.

RESULTS

Overall, 38 patients (115 lesions) and 23 patients (75 lesions) were analyzed in the ARC and control groups, respectively. In the ARC group, T/NL90Y and TD90Y were significantly higher than T/NLMAA and TDMAA. Median (IQR) T/NL90Y was 2.16 (2.15) versus 1.74 (1.43) for T/NLMAA (p < 0.001). Median (IQR) TD90Y was 90.96 Gy (98.31 Gy) versus 73.72 Gy (63.82 Gy) for TDMAA (p < 0.001). In this group, the differences were highly significant for neuroendocrine metastases (NEM) and HCC and less significant for colorectal metastases (CRM). In the control group, no significant differences were demonstrated.

CONCLUSION

The use of an ARC significantly improves tumor deposition in liver radioembolization with resin microspheres.

Analysis of differences between 99mTc-MAA SPECT- and 90Y-microsphere PET-based dosimetry for hepatocellular carcinoma selective internal radiation therapy

Background

The aim of this study was to compare predictive and post-treatment dosimetry and analyze the differences, investigating factors related to activity preparation and delivery, imaging modality used, and interventional radiology.

Methods

Twenty-three HCC patients treated by selective internal radiation therapy with ⁹⁰Y glass microspheres were included in this study. Predictive and post-treatment dosimetry were calculated at the voxel level based on ^99mTc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT respectively. Dose distribution was analyzed through mean dose, metrics extracted from dose-volume histograms, and Dice similarity coefficients applied on isodoses. Reproducibility of the radiological gesture and its influence on dose deviation was evaluated.

Results

⁹⁰Y delivered activity was lower than expected in 67% (16/24) of the cases mainly due to the residual activity. A mean deviation of − 6 ± 11% was observed between the delivered activity and the ⁹⁰Y PET’s FOV activity. In addition, a substantial difference of − 20 ± 8% was measured on ⁹⁰Y PET images between the activity in the liver and in the whole FOV. After normalization, ^99mTc-MAA SPECT dosimetry was highly correlated and concordant with ⁹⁰Y-microsphere PET dosimetry for all dose metrics evaluated (ρ = 0.87, ρ_c = 0.86, P = 3.10⁻⁸ and ρ = 0.91, ρ_c = 0.90, P = 7.10⁻¹⁰ for tumor and normal liver mean dose respectively for example). Besides, mean tumor dose deviation was lower when the catheter position was identical than when it differed (16 Gy vs. 37 Gy, P = 0.007). Concordance between predictive and post-treatment dosimetry, evaluated with Dice similarity coefficients applied on isodoses, significantly correlated with the distance of the catheter position from artery bifurcation (P = 0.04, 0.0004, and 0.05, for 50 Gy, 100 Gy, and 150 Gy isodoses respectively).

Conclusions

Discrepancies between planned activity and activity measured on ⁹⁰Y PET images were observed and seemed to be mainly related to clinical hazards and equipment issues. Predictive vs. post-treatment comparison of relative dose distributions between tumor and normal liver showed a good correlation and no significant difference highlighting the predictive value of ^99mTc MAA SPECT/CT-based dosimetry. Besides, the reproducibility of catheter tip position appears critical in the agreement between predictive and actual dose distribution.