Relationship between quantitative cardiac neuronal imaging with 123I-meta-iodobenzylguanidine and hospitalization in patients with heart failure

Iodine-123 Metaiodobenzylguanidine (I-123 MIBG) in Clinical Applications: A Comprehensive Review

Iodine-123 metaiodobenzylguanidine (I-123 MIBG) is a crucial radiopharmaceutical widely used in nuclear medicine for its diagnostic capabilities in both cardiology and oncology. This review aims to present a comprehensive evaluation of the clinical applications of I-123 MIBG, focusing on its use in diagnosing and managing various diseases. In cardiology, I-123 MIBG has proven invaluable in assessing cardiac sympathetic innervation, particularly in patients with heart failure, where it provides prognostic information that guides treatment strategies. In oncology, I-123 MIBG is primarily utilized for imaging neuroendocrine tumors, such as neuroblastoma and pheochromocytoma, where it offers high specificity and sensitivity in the detection of adrenergic tissue. Additionally, its role in neurology, specifically in differentiating between Parkinson's disease, dementia, and Lewy body dementia, has become increasingly significant due to its ability to identify postganglionic sympathetic dysfunction. Despite its established clinical utility, the use of I-123 MIBG is not without limitations, including variability in imaging protocols and interpretation challenges. This review will explore these issues and discuss emerging alternatives, while also highlighting areas where I-123 MIBG continues to be a gold standard. By synthesizing the current research, this article aims to provide a clear understanding of the strengths, limitations, and prospects of I-123 MIBG in clinical practice.

Usefulness of the 2-year iodine-123 metaiodobenzylguanidine-based risk model for post-discharge risk stratification of patients with acute decompensated heart failure

PURPOSE

A four-parameter risk model that included cardiac iodine-123 metaiodobenzylguanidine (MIBG) imaging and readily available clinical parameters was recently developed for prediction of 2-year cardiac mortality risk in patients with chronic heart failure. We sought to validate the ability of this risk model to predict post-discharge clinical outcomes in patients with acute decompensated heart failure (ADHF) and to compare its prognostic value with that of the Acute Decompensated Heart Failure National Registry (ADHERE) and Get With The Guidelines-Heart Failure (GWTG-HF) risk scores.

METHODS

We studied 407 consecutive patients who were admitted for ADHF and survived to discharge, with definitive 2-year outcomes (death or survival). Cardiac MIBG imaging was performed just before discharge. The 2-year cardiac mortality risk was calculated using four parameters, namely age, left ventricular ejection fraction, New York Heart Association functional class, and cardiac MIBG heart-to-mediastinum ratio on delayed images. Patients were stratified into three groups based on the 2-year cardiac mortality risk: low- (< 4%), intermediate- (4-12%), and high-risk (> 12%) groups. The ADHERE and GWTG-HF risk scores were also calculated.

RESULTS

There was a significant difference in the incidence of cardiac death among the three groups stratified using the 2-year cardiac mortality risk model (p < 0.0001). The 2-year cardiac mortality risk model had a higher C-statistic (0.732) for the prediction of cardiac mortality than the ADHERE and GWTG-HF risk scores.

CONCLUSION

The 2-year MIBG-based cardiac mortality risk model is useful for predicting post-discharge clinical outcomes in patients with ADHF.

TRIAL REGISTRATION NUMBER

UMIN000015246, 25 September 2014.

Usefulness of 5 Minutes ¹²³I-mIBG Scan in Parkinson's Disease and Heart Failure

BACKGROUND

The use of 123I-mIBG has been approved for decades for Parkinson's disease (PD) diagnosis and as a predictor of mortality and potentially fatal events in patients with Heart Failure (HF). The standardized technique includes an early acquisition (15 minutes from injection), and a late acquisition (240 minutes). Early images mainly represent interstitial uptake, whereas delayed images represent actual neuronal uptake, however, it is reasonable to affirm that different pathological situations, such as PD and HF, imply a different meaning for early and late imaging.

OBJECTIVE

This prospective study aims to investigate the clinical usefulness of an immediate planar 123I-mIBG image acquisition (5 minutes) both in patients with PD and in patients with HF.

METHODS

115 patients referred to 123I-mIBG cardiac imaging in Nuclear Medicine Center have been enrolled (60 patients with PD, absence of diabetes and/or cardiologic pathology, Hoehn e Yahr classification ≤ 1.5; 55 patients with cardiomyopathy, diagnosis of HF, NYHA class I-III). 123I-mIBG planar anterior thoracic acquisitions were performed after 5 (immediate), 15 (early) and 240 (late) minutes from injection and H/M ratios were calculated.

RESULTS

In PD group H/M mean values resulted in 1.58±0.22 for immediate (5 min), 1.61±0.26 for early (15 min) and 1.59±0.37 for late (240 min) acquisitions. In the HF group, H/M mean values resulted in 1.63±0.24 for immediate (5 min), 1.65±0.22 for early (15 min) and 1.57±0.17 for late (240 min) acquisitions, respectively. H/M values obtained at 5 min and 15 min are provided similar results, with no statistical difference (p = ns) regardless of the pathology examined (PD or HF groups). The statistical analyses validated the diagnostic role of immediate acquisition (5 min) and early acquisition (15 min) in PD group as compared to the standardized late acquisition (240 min). On the contrary, in HF group, immediate and early acquisition, as compared to late acquisition (240 min), is not validated as a major cardiac events predictor.

CONCLUSION

Our results indicate the potential role of immediate (5 min) or early (15 min) acquisition in replacement of standardized 240 minutes acquisition in PD patients, but this result is not confirmed in HF patients, in which the acquisition at 240 min is confirmed as the most affordable timing for image interpretation, emphasizing the different pathophysiology that underlies these two pathologies.

Abdominal obesity, and not general obesity, is associated with a lower 123I MIBG heart-to-mediastinum ratio in heart failure patients with preserved ejection fraction

BACKGROUND

The relationship between general obesity or abdominal obesity (abdominal circumference of ≥85 cm in men and ≥ 90 cm in women) and the heart-to-mediastinum ratio (HMR), a measure of cardiac sympathetic innervation, on cardiac iodine-123-metaiodobenzylguanidine scintigraphy (MIBG) in patients with heart failure with preserved ejection fraction (HFpEF) has not been clarified.

METHODS

A total of 239 HFpEF patients with both MIBG and abdominal circumference data were examined. We divided these patients into those with abdominal obesity and those without it. In the cardiac MIBG study, early phase image was acquired 15-20 min after injection, and late phase image was acquired 3 h after the early phase. A HMR obtained from a low-energy type collimator was converted to that obtained by a medium-energy type collimator.

RESULTS

Early and late HMRs were significantly lower in those with abdominal obesity, although washout rates were not significantly different. The incidence of patients with early and late HMRs <2.2 was significantly higher in those with abdominal obesity. Multivariate linear regression analysis revealed that abdominal obesity was independently associated with early HMR (standardized β = -0.253, P = 0.003) and late HMR (standardized β = -0.222, P = 0.010). Multivariate logistic regression analysis revealed that abdominal obesity was independently associated with early (odds ratio [OR] [95% confidence interval {CI}] = 4.25 [2.13, 8.47], P < 0.001) and late HMR < 2.2 (OR [95% CI] = 2.06 [1.11, 3.83], P = 0.022). Elevated BMI was not significantly associated with low early and late HMR. The presence of abdominal obesity was significantly associated with low early and late HMR even in patients without elevated BMI values.

CONCLUSION

Abdominal obesity, but not general obesity, in HFpEF patients was independently associated with low HMR, suggesting that visceral fat may contribute to decreased cardiac sympathetic activity in patients with HFpEF.

TRIAL REGISTRATION

UMIN000021831.

Cardiac sympathetic nervous system imaging with 123I-meta-iodobenzylguanidine: Perspectives from Japan and Europe

Cardiac sympathetic nervous system dysfunction is closely associated with risk of serious cardiac events in patients with heart failure (HF), including HF progression, pump-failure death, and sudden cardiac death by lethal ventricular arrhythmia. For cardiac sympathetic nervous system imaging, 123I-meta-iodobenzylguanidine (123I-MIBG) was approved by the Japanese Ministry of Health, Labour and Welfare in 1992 and has therefore been widely used since in clinical settings. 123I-MIBG was also later approved by the Food and Drug Administration (FDA) in the United States of America (USA) and it was expected to achieve broad acceptance. In Europe, 123I-MIBG is currently used only for clinical research. This review article is based on a joint symposium of the Japanese Society of Nuclear Cardiology (JSNC) and the American Society of Nuclear Cardiology (ASNC), which was held in the annual meeting of JSNC in July 2016. JSNC members and a member of ASNC discussed the standardization of 123I-MIBG parameters, and clinical aspects of 123I-MIBG with a view to further promoting 123I-MIBG imaging in Asia, the USA, Europe, and the rest of the world.