Assessment of global cardiac I-123 MIBG uptake and washout using volumetric quantification of SPECT acquisitions

Abstract

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.

Quantitative Analysis of Dynamic 123I-mIBG SPECT Imaging Data in Healthy Humans with a Population-Based Metabolite Correction Method

“…However, 2D planar imaging is not fully quantitative, because of the superposition of background structures with the 2D heart region of interest and lack of corrections for attenuation and scatter. Three-dimensional (3D) SPECT 123 I-mIBG imaging has been proposed to overcome this limitation and enable evaluation of regional myocardial tracer uptake (6)(7)(8)(9)(10)(11). However, the HMR and WOR values change with the timing for early and delayed imaging in both 2D planar and 3D SPECT, which are only surrogates of tracer retention and kinetics.…”

123I-MIBG SPECT for Evaluation of Patients with Heart Failure

“…These have included the introduction of iterative reconstruction techniques with compensation for scatter and septal penetration (53,58,59) and the use of volumetric analysis techniques (60). The development of 123 I-MIBG databases for healthy subjects has also provided a more reliable means for quantifying the significance of reduced uptake in HF and other cardiology patients (6).…”

The impact of system matrix dimension on small FOV SPECT reconstruction with truncated projections

“…The uptake ratios between the myocardium and the rest of the organs were varied to simulate realistic 99m Tc-Tetrofosmin myocardial perfusion scans (phantoms 1 and 2) 27 and 123 I-metaiodobenzylguanidine ( 123 I-mIBG) cardiac studies (phantoms 3 and 4). 28 of radioactivity in each organ is shown in Table I. A transmural defect with a 50% reduction of the myocardial radioactivity was also inserted in all the phantoms.…”