Dataset Information

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in ¹²³I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.

ABSTRACT:

Background

Septal penetration causes collimator-dependent differences in the heart-to-mediastinum (H/M) ratio in ¹²³I-metaiodobenzylguanidine (MIBG) cardiac imaging. We investigated generally applicable methods to correct such differences.

Methods and results

Four hours after ¹²³I-MIBG injection, 40 patients underwent anterior chest imaging successively with medium-energy (ME) and various non-ME collimators. The H/M ratios obtained with the non-ME collimators before and after ¹²³I-dual-window penetration correction were compared with the ME-derived standard values to determine patient-based conversion equations for empiric and combined corrections, respectively. A ¹²³I point source was imaged with various collimators, and the central ratio, the ratio of count in a small central region of interest to count in a large one, was calculated. The method of predicting the conversion equations from the central ratios was determined. Correction using the patient-based conversion equations removed systematic underestimation of the H/M ratios obtained with the non-ME collimators, and combined correction depressed residual random errors to some degree. Point-source-based equations yielded results comparable to the patient-based equations.

Conclusions

Empiric and combined corrections effectively reduce collimator-dependent differences in the H/M ratio. The conversion equations can be predicted from simple point-source imaging, which would allow to apply these corrections to data obtained with various collimators.

SUBMITTER: Inoue Y

PROVIDER: S-EPMC5629249 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Publications

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in <sup>123</sup>I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.

Inoue Yusuke Y Abe Yutaka Y Kikuchi Kei K Matsunaga Keiji K Masuda Ray R Nishiyama Kazutoshi K

Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 20160601 5

<h4>Background</h4>Septal penetration causes collimator-dependent differences in the heart-to-mediastinum (H/M) ratio in <sup>123</sup>I-metaiodobenzylguanidine (MIBG) cardiac imaging. We investigated generally applicable methods to correct such differences.<h4>Methods and results</h4>Four hours after <sup>123</sup>I-MIBG injection, 40 patients underwent anterior chest imaging successively with medium-energy (ME) and various non-ME collimators. The H/M ratios obtained with the non-ME collimators ...[more]

PMID: 27251143

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Project description:BackgroundSince three-dimensional segmentation of cardiac region in 123I-metaiodobenzylguanidine (MIBG) study has not been established, this study aimed to achieve organ segmentation using a convolutional neural network (CNN) with 123I-MIBG single photon emission computed tomography (SPECT) imaging, to calculate heart counts and washout rates (WR) automatically and to compare with conventional quantitation based on planar imaging.MethodsWe assessed 48 patients (aged 68.4 ± 11.7 years) with heart and neurological diseases, including chronic heart failure, dementia with Lewy bodies, and Parkinson's disease. All patients were assessed by early and late 123I-MIBG planar and SPECT imaging. The CNN was initially trained to individually segment the lungs and liver on early and late SPECT images. The segmentation masks were aligned, and then, the CNN was trained to directly segment the heart, and all models were evaluated using fourfold cross-validation. The CNN-based average heart counts and WR were calculated and compared with those determined using planar parameters. The CNN-based SPECT and conventional planar heart counts were corrected by physical time decay, injected dose of 123I-MIBG, and body weight. We also divided WR into normal and abnormal groups from linear regression lines determined by the relationship between planar WR and CNN-based WR and then analyzed agreement between them.ResultsThe CNN segmented the cardiac region in patients with normal and reduced uptake. The CNN-based SPECT heart counts significantly correlated with conventional planar heart counts with and without background correction and a planar heart-to-mediastinum ratio (R2 = 0.862, 0.827, and 0.729, p < 0.0001, respectively). The CNN-based and planar WRs also correlated with and without background correction and WR based on heart-to-mediastinum ratios of R2 = 0.584, 0.568 and 0.507, respectively (p < 0.0001). Contingency table findings of high and low WR (cutoffs: 34% and 30% for planar and SPECT studies, respectively) showed 87.2% agreement between CNN-based and planar methods.ConclusionsThe CNN could create segmentation from SPECT images, and average heart counts and WR were reliably calculated three-dimensionally, which might be a novel approach to quantifying SPECT images of innervation.

Project description:BackgroundPatient radioprotection in myocardial perfusion imaging (MPI)-SPECT is important but difficult to optimize. The aim of this study was to adjust injected activity according to patient size-weight or BMI-by using a cardiofocal collimator camera.MethodsThe correlation equation between size and observed counts in image was determined in patients who underwent stress Tc-99m-sestamibi MPI-SPECT/CT with a cardiofocal collimator-equipped conventional Anger SPECT/CT system. Image quality analyses by seven nuclear physicians were conducted to determine the minimum patient size-independent observed count threshold that yielded sufficient image quality for perfusion-defect diagnosis. These data generated an equation that can be used to calculate personalized activity for patients according to their size.ResultsAnalysis of consecutive patients (n = 294) showed that weight correlated with observed counts better than body mass index. The correlation equation was used to generate the equation that expressed the relationship between observed counts, patient weight, and injected activity. Image quality analysis with 50 images yielded an observed count threshold of 22,000 counts. Using this threshold means that the injected activity in patients with < 100 kg would be reduced (e.g., by 67% in 45-kg patients). Patients who are heavier than 100 kg would also benefit from the use of the threshold because although the injected activity would be higher (up to 78% for 150-kg patients), good image quality would be obtained.ConclusionsThis study provided a method for determining the optimal injected activity according to patient weight without compromising the image quality of conventional Anger SPECT/CT systems equipped with a cardiofocal collimator. Personalized injected activities for each patient weight ranging from 45 to 150 kg were generated, to standardize the resulting image quality independently of patient attenuation. This approach improves patient/staff radioprotection because it reduces the injected activity for < 100-kg patients (the majority of patients).

Dataset Information

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in ¹²³I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.

Background

Methods and results

Conclusions

Publications

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in <sup>123</sup>I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in 123I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.

Background

Methods and results

Conclusions

Publications

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in <sup>123</sup>I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Correction of collimator-dependent differences in the heart-to-mediastinum ratio in ¹²³I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging.