A prediction model for 5-year cardiac mortality in patients with chronic heart failure using 123I-metaiodobenzylguanidine imaging

Nakata

2015

J Nucl Med

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Cardiac neuroimaging with 123 I-metaiodobenzylguanidine ( 123 I-MIBG) has been officially used in clinical practice in Japan since 1992. The nuclear cardiology guidelines of the Japanese Circulation Society, revised in 2010, recommended cardiac 123 I-MIBG imaging for the management of heart failure (HF) patients, particularly for the assessment of HF severity and prognosis of HF patients. Consensus in North American and European countries regarding incorporation into clinical practice, however, has not been established yet. This article summarizes 22 y of clinical applications in Japan of 123 I-MIBG imaging in the field of cardiology; these applications are reflected in cardiology guidelines, including recent methodologic advances. A standardized cardiac 123 I-MIBG parameter, the heartto-mediastinum ratio (HMR), is the basis for clinical decision making and enables common use of parameters beyond differences in institutions and studies. Several clinical studies unanimously demonstrated its potent independent roles in prognosis evaluation and risk stratification irrespective of HF etiologies. An HMR of less than 1.6−1.8 and an accelerated washout rate are recognized as high-risk indicators of pump failure death, sudden cardiac death, and fatal arrhythmias and have independent and incremental prognostic values together with known clinical variables, such as left ventricular ejection fraction and brain natriuretic peptide. Another possible use of this imaging technique is the selection of therapeutic strategy, such as pharmacologic treatment and nonpharmacologic treatment with an implantable cardioverter-defibrillator or cardiac resynchronization device; however, this possibility remains to be investigated. Recent multiple-cohort database analyses definitively demonstrated that patients who were at low risk for lethal events and who were defined by an HMR of greater than 2.0 on 123 I-MIBG studies had a good long-term prognosis. Future investigations of cardiac 123 I-MIBG imaging will contribute to better risk stratification of low-risk and high-risk populations, to the establishment of costeffective use of this imaging technique for the management of HF patients, and to worldwide acceptance of this imaging technique in clinical cardiology practice.

Section: Identification Of Low-risk Patients With Hfmentioning

confidence: 92%

Section: Standardization Of Hmr For Prognostic Evaluationmentioning

confidence: 99%

Section: Limitations and Future Directions Of Cardiac 123 I-mibg Imagingmentioning

confidence: 99%

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Cardiac ¹²³I-MIBG Imaging for Clinical Decision Making: 22-Year Experience in Japan

Nakata

2015

J Nucl Med

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“…Standardization is also important for identifying appropriate thresholds to differentiate good and bad prognoses [3][4][5], as well as for incorporating 123I-MIBG HMR into cardiac mortality risk models [8]. This standardization would also help create large databases in Europe, North America and Japan.…”

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confidence: 99%

The time has come to standardize 123I-MIBG heart-to-mediastinum ratios including planar and SPECT methods

Eur J Nucl Med Mol Imaging

Okuda

Matsuo

et al. 2015

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Bellevre et al. used D-SPECT (Spectrum Dynamics, Israel) with a cadmium zinc telluridebased camera for the determination of the heart-to-mediastinum ratio (HMR) of myocardial While the 123 I-MIBG study has been widely used to patients with chronic heart failure and Levy body disease, most studies have used planar HMR [3][4][5]. Whether we can still use the previous numerous stock of data and how we can connect the follow-up data in the same series of patients are important issues. Considering the exchangeability of data between the Anger-type camera and D-SPECT, the authors of this study successfully used an anterior view equivalent planogram and introduced a correction formula to standardize the data between the two systems [1].We have proposed the use of standardized HMR to the condition obtained with the most common ME general purpose collimators for all 123I-MIBG studies irrespective of the collimator used in an individual hospital [6,7]. The conversion coefficient (CC) for the mathematical reference value using the most popular ME collimators was CC = 0.88 [7]. Therefore, an institutional HMR (HMRi) can be converted to the standard HMR (HMRstd) using the following equation: HMRstd = 0.88/CCi × (HMRi − 1) + 1, where CCi is the CC of the institutional camera/collimator system. The CC ranged from 0.5 to 1.0 depending on the collimator type used [1].

“…The varying factors among institutions that affect the stability of results include radiotracer doses administered, image acquisition protocols, ROI settings for processing (4,5), and corrections for camera-collimator differences. Cardiac mortality risk models were also created (6), and these are addressed elsewhere in this article. However, a fluctuating HMR influenced the final prediction of cardiac mortality, which could seriously impact decisions about patient management.…”

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confidence: 99%

<sup>123</sup>I-Meta-Iodobenzylguanidine Imaging

Annals of Nuclear Cardiology

2016

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Abstract123 I-meta-iodobenzylguanidine (MIBG) is a potent prognostic marker of chronic heart failure (CHF). However, inter-institutional variations due to methodological variations required minimization before 123 I-MIBG findings could be universally applied to the diagnosis, treatment and prognosis of CHF. Therefore, protocols including data acquisition, setting regions of interest for calculating heart-to-mediastinum ratios (HMR) and crosscalibration of HMR among institutions required standardization. A cross-calibration phantom was introduced to overcome institutional differences, and a large amount of experimental data were collected, which enabled multicenter comparisons and the creation of large-scale prognostic databases. Thereafter, cardiac mortality risk models to estimate short-and long-term (two and five years, respectively) mortality were created based on a standardized 123 I-MIBG HMR. The ability of these models to accurately determine prognosis is currently Kenichi Nakajima Department of Nuclear Medicine, Kanazawa University Hospital, 13-1 Takara-machi, Kanazawa, Japan 920-8641 E-mail: nakajima@med.kanazawa-u.ac.jp ME general-purpose (MEGP) collimators, but low-energy high-resolution (LEHR), low-energy general-purpose (LEGP), and low-medium-energy (LME) collimators are also popular in Japan. Single-photon emission computed tomography (SPECT) imaging also allows 360º or 180º rotation and it can score defects similar to perfusion defects (7,8). The Japanese Society Nuclear Medicine working group created normal early / late, 180º / 360º and gender-specific databases (9) that work with any software and are applicable to clinical and research purposes. Administration of 123 I-MIBG and data acquisition Heart-to-mediastinum ratio: ROI setting and stabilityThe most popular index of cardiac MIBG uptake is early and late HMR. Although the HMR is a simple average count ratio between the heart and mediastinum, the location, size and (10) and the semiautomatic smartMIBG software used in Japan (5). This software needs only to point towards the center of the heart, and then a circular ROI on the heart and a rectangular ROI on the upper mediastinum are automatically determined. The mediastinal ROI was set at 10% of the body width and 30% of the height from the center of the heart to the upper border of the mediastinum. The optimal mediastinal region was automatically searched vertically to determine the minimal count on the mediastinum. The HMR remains relatively stable for three or four hours, when late images can be acquired (11,12). A washout rate (WR) can also be calculated using the formula:WR (%) = (early heart count-late heart count) / early heart count×100.The mediastinal count in this formula is usually subtracted from the heart count as the background, and a 123 I (half-life, 13 h) decay is corrected using a decay factor at three to four hours after the initial image acquisition (correction factor of ×1.17and ×1.24, respectively). Although ROI settings are generally considered reproducible (13), the sem...