This study investigated the feasibility of quantitative accuracy and harmonized image quality in 89 Zr-PET/CT multicenter studies. Methods: Five PET/CT scanners from 3 vendors were included. 89 Zr activity was measured in a central dose calibrator before delivery. Local activity assays were based on volume as well as on the local dose calibrator. Accuracy and image noise were determined from a cross calibration experiment. Image quality was assessed from recovery coefficients derived from different volume-of-interest (VOI) methods (VOI A50% , based on a 3-dimensional isocontour at 50% of the maximum voxel value with local background correction; VOI Max , based on the voxel with the highest uptake; and VOI 3Dpeak , based on a spheric VOI of 1.2-cm diameter positioned so as to maximize the enclosed average). PET images were analyzed before and after postreconstruction smoothing, applied to match image noise. Results: PET/CT accuracy and image noise ranged from 23% to 10% and from 13% to 22%, respectively. VOI 3Dpeak produced the most reproducible recovery coefficients. After calibration of the local dose calibrator to the central dose calibrator, differences between the local activity assays were within 6%. Conclusion: This study showed that quantitative accuracy and harmonized image quality can be reached in 89 Zr PET/CT multicenter studies. PET using labeled monoclonal antibodies, also known as immuno-PET, shows promise as a tool to predict the outcome of cancer treatment based on monoclonal antibodies (1). Their kinetics dictate the need for a positron label with a long half-life. An ideal radionuclide is 89 Zr (half-life, 78.41 h) because its physical half-life matches the biologic half-life of most antibodies. Additionally, it can easily and stably be coupled to monoclonal antibodies (2). To date, all 89 Zr-monoclonal antibody PET/CT studies that have been reported were performed within a single center (3-5). More recently, several multicenter studies have been initiated. Multicenter studies with 18 F-labeled tracers have shown the need for standardization of image acquisition, reconstruction, and analysis procedures, such as outlined in the European Association of Nuclear Medicine guidelines for tumor imaging (6) and implemented in the form of an accreditation (EANM Research Ltd.[EARL]). For 89 Zr, there are several additional factors that need to be considered: nonprompt emission of 909-keV g rays after each positron emission may influence cross calibration between the local dose calibrator and the PET/CT camera, and low counting rates (due to both low positron abundance and low injected activity) may potentially lead to poorer image quality. The aim of this study was therefore to investigate the feasibility of quantitative accuracy and harmonized image quality in 89 Zr-PET/CT multicenter studies. MATERIALS AND METHODS ScannersThree Gemini TF PET/CT scanners (Philips Healthcare) (7), a Biograph mCT PET/CT scanner (Siemens Medical Solutions) (8), and a Discovery-690 PET/CT scanner (GE Healthcare) (9) were us...

BackgroundAssessment of cardiac innervation using single-photon emission computer tomography (SPECT) is less established than planar imaging, but may be more suitable for quantification. Therefore, a volumetric quantification of I-123 MIBG SPECT acquisitions was performed. Reproducibility, the effects of extra cardiac I-123 MIBG uptake and the relation with conventional planar indices were evaluated.Methods54 patients referred for planar and SPECT I-123 MIBG acquisitions were included. Ellipsoidal or box-shaped volumes of interest were placed on the left ventricle, cardiac lumen, mediastinum, lung and liver. SPECT segmentation was performed twice in all patients. Indices were determined based on the heart-to-mediastinum (HM), myocardial wall-to-mediastinum and myocardial wall-to-lumen regions. HM ratios and washout rates were also determined based on anterior planar images.ResultsCardiac count densities were highly reproducible (CV 1.5-5.4, ICC 0.96-0.99) and inter-rater variability was low (CV 1.8-6.8, ICC 0.94-0.99). Mediastinal uptake was an important explanatory variable of uptake in the entire heart (early R2 = 0.36; delayed R2 =0.43) and myocardial wall (early R2 = 0.28; delayed R2 = 0.37). Lung washout was an explanatory variable of organ washout of the heart (heart R2 = 0.38; myocardial wall R2 = 0.33). In general, SPECT indices showed moderate-to-good correlations with the planar uptake (PCC 0.497-0.851).ConclusionBy applying a volumetric segmentation method we were able to segment the heart in all patients. SPECT I-123 MIBG quantification was found to be highly reproducible and had a moderate to good correlation with the planar indices.

In an exercise stressed population, TID is determined by both the degree of ischemia and the heart-rate difference between the two acquisition moments. TID within the adenosine population was found to be highly proportional with the HR, rather than with the degree of ischemia.

PurposeSemiquantitative analysis of myocardial perfusion scintigraphy (MPS) has reduced inter- and intraobserver variability, and enables researchers to compare parameters in the same patient over time, or between groups of patients. There are several software packages available that are designed to process MPS data and quantify parameters. In this study the performances of two systems, quantitative gated SPECT (QGS) and 4D-MSPECT, in the processing of clinical patient data and phantom data were compared.MethodsThe clinical MPS data of 148 consecutive patients were analysed using QGS and 4D-MSPECT to determine the end-diastolic volume, end-systolic volume and left ventricular ejection fraction. Patients were divided into groups based on gender, body mass index, heart size, stressor type and defect type. The AGATE dynamic heart phantom was used to provide reference values for the left ventricular ejection fraction.ResultsAlthough the correlations were excellent (correlation coefficients 0.886 to 0.980) for all parameters, significant differences (p < 0.001) were found between the systems. Bland-Altman plots indicated that 4D-MSPECT provided overall higher values of all parameters than QGS. These differences between the systems were not significant in patients with a small heart (end-diastolic volume <70 ml). Other clinical factors had no direct influence on the relationship. Additionally, the phantom data indicated good linear responses of both systems.ConclusionThe discrepancies between these software packages were clinically relevant, and influenced by heart size. The possibility of such discrepancies should be taken into account when a new quantitative software system is introduced, or when multiple software systems are used in the same institution.

PurposeLeft ventricular dyssynchrony may predict response to cardiac resynchronization therapy and may well predict adverse cardiac events. Recently, a geometrical approach for dyssynchrony analysis of myocardial perfusion scintigraphy (MPS) was introduced. In this study the feasibility of this geometrical method to detect dyssynchrony was assessed in a population with a normal MPS and in patients with documented ventricular dyssynchrony.MethodsFor the normal population 80 patients (40 men and 40 women) with normal perfusion (summed stress score ≤2 and summed rest score ≤2) and function (left ventricular ejection fraction 55–80%) on MPS were selected; 24 heart failure patients with proven dyssynchrony on MRI were selected for comparison. All patients underwent a 2-day stress/rest MPS protocol. Perfusion, function and dyssynchrony parameters were obtained by the Corridor4DM software package (Version 6.1).ResultsFor the normal population time to peak motion was 42.8 ± 5.1% RR cycle, SD of time to peak motion was 3.5 ± 1.4% RR cycle and bandwidth was 18.2 ± 6.0% RR cycle. No significant gender-related differences or differences between rest and post-stress acquisition were found for the dyssynchrony parameters. Discrepancies between the normal and abnormal populations were most profound for the mean wall motion (p value <0.001), SD of time to peak motion (p value <0.001) and bandwidth (p value <0.001).ConclusionIt is feasible to quantify ventricular dyssynchrony in MPS using the geometrical approach as implemented by Corridor4DM.