Impact of age on myocardial uptake of 123I-mIBG in older adult subjects without coronary heart disease

Background

The purpose of this study was to examine the relationship between myocardial uptake of ¹²³I-mIBG and age in older normal adult subjects.

Methods

94 subjects (age 29-82, mean 58.5) without coronary heart disease were studied. All subjects underwent early and delayed planar and 4-hour SPECT ¹²³I-mIBG imaging. ¹²³I-mIBG uptake was quantified as heart/mediastinum ratio on planar images (H/M _p) and on SPECT images (H/M _s) reconstructed by filtered backprojection, ordered subsets-expectation maximization (OSEM), and OSEM with compensation for collimator septal penetration (DSP). Relationships between age and ¹²³I-mIBG uptake were examined by correlation analysis, t-tests, and analysis of variance.

Results

There was no significant correlation between age and H/M _p, reflecting comparable increases in activity in the two regions of interest with age. Results on SPECT analyses were comparable, with no significant correlation between age and H/M _s. Using DSP, ¹²³I-mIBG H/M _s was significantly higher in subjects ≥70 of age compared with younger subjects.

Conclusions

Both cardiac and background uptake of ¹²³I-mIBG increase with age in older subjects without coronary heart disease, resulting in stability of H/M results (planar and SPECT). This study suggests that prognostic analyses of quantitative ¹²³I-mIBG uptake in patients with heart disease do not require adjustment for patient age.     

The utility of ADMIRE-HF risk score in predicting serious arrhythmic events in heart failure patients: Incremental prognostic benefit of cardiac 123I-mIBG scintigraphy

Background

A minority of heart failure (HF) patients who undergo implantable cardioverter defibrillator (ICD) implantation for primary prevention of sudden cardiac death (SCD) receive device therapy. Whether the addition of mIBG scintigraphy to conventional markers of arrhythmic risk can provide incremental risk stratification in HF patients has not been investigated.

Methods

We identified 778 patients from the ADMIRE-HF study with LVEF < 35% and class II or III HF symptoms who did not have an ICD at the time of enrollment. Patients were followed up prospectively (median = 17 months) for occurrence of arrhythmic events (ArE). Heart-to-mediastinum ratio (HMR) was determined as a measure of relative myocardial sympathetic nerve activity at baseline using ¹²³I-mIBG. The primary endpoint was the first occurrence of ArE: a composite of SCD, appropriate ICD therapy, resuscitated cardiac arrest or sustained ventricular tachycardia. Multivariate regression was used to determine independent predictors of ArE and to derive a risk score for ArE prediction. The score was used to group patients according to their risk for ArE. Integrated discrimination improvement (IDI) was used to quantify improvement in risk assessment with addition of HMR.

Results

ArE occurred in 54 patients (6.9%). ArE predictors were: HMR < 1.6 (HR 3.5, 95% CI [1.52-8], P = .02), LVEF < 25% (HR 2.0, 95% CI [1.28-3.05], P = .04) and SBP < 120 (HR 1.2, 95% CI [1.03-1.39], P = .02). Event rates in the low-, intermediate-, and high risk groups were 2, 10 and 16%, respectively (P = .001). The score significantly improved risk prediction (IDI = 45%, P 0.03).

Conclusion

¹²³I-mIBG significantly provides incremental risk stratification for ArE in HF patients.     

Influence of myocardial region of interest definition on quantitative analysis of planar 123I-mIBG images

Purpose

In planar ¹²³I-mIBG myocardial imaging, definition of the heart region of interest (ROI) is a critical step in quantifying uptake. The present study evaluated the impact of changes in heart ROI size on quantitative results in subjects with good and poor uptake.

Methods

Reference irregular whole-heart and square upper mediastinum ROIs were defined visually on 531 planar ¹²³I-mIBG images. Based on the reference heart ROI, an automated program created two other ROIs: one larger (+1 pixel) and one smaller (?1 pixel), the stated numbers representing the spacing intervals between each epicardial boundary pixel. Two additional smaller ROIs (?2 and ?3 pixels) were drawn for the 100 images (19 %) with a heart/mediastinum (H/M) ratio ≤1.30. The number of pixels, the counts per pixel, and the H/M ratio for each heart ROI were calculated and compared to that in the reference ROI. Washout rate and changes as a function of ROI size were also calculated for 110 subjects who had both early and late images.

Results

The mean changes in heart ROI size ranged from +19.0 % for the +1 pixel to ?44.4 % for the ?3 pixels ROI. For the +1 and ?1 pixel ROIs, mean relative counts per pixel changes were ?1.2 % and +0.7 %, respectively, with corresponding ranges of change in the H/M ratio of ?0.12 to +0.05 and ?0.05 to +0.11. For scans with H/M ratio ≤1.30, mean relative counts per pixel changes were 0, 0, ?0.7 %, and ?1.4 % for the four ROIs, with range of change in the H/M ratio from ?0.13 to +0.05. Mean washout rates were almost identical for the reference ROIs (45.0 %) and the +1 pixel and ?1 pixel heart ROIs (44.9 % and 45.1 %, respectively).

Conclusion

Significant changes in the size of the best visually defined heart ROI produce minimal, clinically inconsequential changes in the H/M ratio and washout rate, even in subjects with significantly reduced myocardial uptake of ¹²³I-mIBG.     

123I-mIBG Scintigraphy to predict risk for adverse cardiac outcomes in heart failure patients: Design of two prospective multicenter international trials

Background  ADMIRE-HF (AdreView Myocardial Imaging for Risk Evaluation in Heart Failure) consists of two identical prospective open-label, multicenter, phase 3 studies (MBG311 and MBG312) evaluating the prognostic usefulness of ¹²³I-mIBG scintigraphy for identifying subjects with heart failure who will experience a major adverse cardiac event. Methods  Subjects with NYHA class II and III heart failure and left ventricular ejection fraction ≤35% were eligible for the trials. Subjects underwent planar and SPECT ¹²³I-mIBG myocardial imaging, as well as echocardiography and gated SPECT ^99mTc-tetrofosmin myocardial perfusion imaging. Subjects are then monitored on a regular basis for 2 years. Time to first occurrence of one of the following—NYHA class progression; potentially life-threatening arrhythmic event (including ICD discharge); or cardiac death, as verified by an independent adjudication panel—will be analyzed in comparison to quantitative parameters derived from ¹²³I-mIBG imaging. The primary efficacy analysis will employ the heart/mediastinum ratio on 4-hour delayed planar imaging, while secondary efficacy analyses will examine quantitative results from both planar and SPECT ¹²³I-mIBG images, as well as from ^99mTc-tetrofosmin SPECT and echocardiography. Conclusion  The results of the ADMIRE-HF trials will provide prospective validation of the potential role of ¹²³I-mIBG scintigraphy in assessing prognosis and developing management strategies for patients with heart failure. Funding Source: GE Healthcare.     

Association between left ventricular regional sympathetic denervation and mechanical dyssynchrony in phase analysis: a cardiac CZT study

Purpose

To evaluate the relationships among myocardial sympathetic innervation, perfusion and mechanical synchronicity assessed with cardiac cadmium-zinc-telluride (CZT) scintigraphy.

Methods

A group of 29 patients underwent an evaluation of myocardial perfusion with ^99mTc-tetrofosmin CZT scintigraphy and adrenergic innervation with ¹²³I-metaiodobenzylguanidine (MIBG) CZT scintigraphy. The summed rest score (SRS), motion score (SMS) and thickening score (STS), as well as the summed ¹²³I-MIBG defect score (SS-MIBG), were determined. Regional tracer uptake for both ^99mTc-tetrofosmin and ¹²³I-MIBG was also calculated. Finally, the presence of significant myocardial mechanical dyssynchrony was evaluated in phase analysis on gated CZT images and the region of latest mechanical activation identified.

Results

Significant mechanical dyssynchrony was present in 17 patients (59 %) and associated with higher SRS (P?=?0.030), SMS (P?<?0.001), STS (P?=?0.003) and early SS-MIBG (P?=?0.037) as well as greater impairments in left ventricular ejection fraction (P?<?0.001) and end-diastolic volume (P?<?0.001). In multivariate analysis a higher end-diastolic volume remained the only predictor of mechanical dyssynchrony (P?=?0.047). Interestingly, while in the whole population regional myocardial perfusion and adrenergic activity were strongly correlated (R?=?0.68), in patients with mechanical dyssynchrony the region of latest mechanical activation was predicted only by greater impairment in regional ¹²³I-MIBG uptake (P?=?0.012) that overwhelmed the effect of depressed regional perfusion.

Conclusion

Left ventricular mechanical dyssynchrony is associated with greater depression in contractile function and greater impairments in regional myocardial perfusion and sympathetic activity. In patients with dyssynchrony, the region of latest mechanical activation is characterized by a significantly altered adrenergic tone.     

Regional heterogeneity in cardiac sympathetic innervation in acute myocardial infarction: relationship with myocardial oedema on magnetic resonance

Purpose

To assess the relationships between myocardial structure and function on cardiac magnetic resonance (CMR) imaging and sympathetic tone on ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy early after myocardial infarction (MI).

Methods

Ten patients underwent ¹²³I-MIBG and ^99mTc-tetrofosmin rest cadmium zinc telluride scintigraphy 4?±?1 days after MI. The segmental left ventricular (LV) relative radiotracer uptake of both ^99mTc-tetrofosmin and early ¹²³I-MIBG was calculated. The day after scintigraphy, on CMR imaging, the extent of ischaemia-related oedema and of myocardial fibrosis (late gadolinium enhancement, LGE) was assessed. Accordingly, the extent of oedema and LGE was evaluated for each segment and segmental wall thickening determined. Based on LGE distribution, LV segments were categorized as "infarcted" (56 segments), "adjacent" (66 segments) or "remote" (48 segments).

Results

Infarcted segments showed a more depressed systolic wall thickening and greater extent of oedema than adjacent segments (p?<?0.001) and remote segments (p?<?0.001). Interestingly, while uptake of ^99mTc-tetrofosmin was significantly depressed only in infarcted segments (p?<?0.001 vs. both adjacent and remote segments), uptake of ¹²³I-MIBG was impaired not only in infarcted segments (p?<?0.001 vs. remote) but also in adjacent segments (p?=?0.024 vs. remote segments). At the regional level, after correction for ^99mTc-tetrofosmin and LGE distribution, segmental ¹²³I-MIBG uptake (p?<?0.001) remained an independent predictor of ischaemia-related oedema.

Conclusion

After acute MI the regional impairment of sympathetic tone extends beyond the area of altered myocardial perfusion and is associated with myocardial oedema.     

Cardiac autonomic imaging with SPECT tracers

Radionuclide cardiac imaging has potential to assess underlying molecular, electrophysiologic, and pathophysiologic processes of cardiac disease. An area of current interest is cardiac autonomic innervation imaging with a radiotracer such as ¹²³I-meta-iodobenzylguanidine (¹²³I-mIBG), a norepinephrine analogue. Cardiac ¹²³I-mIBG uptake can be assessed by planar and SPECT techniques, involving determination of global uptake by a heart-to-mediastinal ratio, tracer washout between early and delayed images, and focal defects on tomographic images. Cardiac ¹²³I-mIBG findings have consistently been shown to correlate strongly with heart failure severity, pre-disposition to cardiac arrhythmias, and poor prognosis independent of conventional clinical, laboratory, and image parameters. ¹²³I-mIBG imaging promises to help monitor a patient’s clinical course and response to therapy, showing potential to help select patients for an ICD and other advanced therapies better than current methods. Autonomic imaging also appears to help diagnose ischemic heart disease and identify higher risk, as well as risk-stratify patients with diabetes. Although more investigations in larger populations are needed to strengthen prior findings and influence modifications of clinical guidelines, cardiac ¹²³I-mIBG imaging shows promise as an emerging technique for recognizing and following potentially life-threatening conditions, as well as improving our understanding of the pathophysiology of various diseases.     

Comparison of 123I-MIBG myocardial scintigraphy,brain perfusion SPECT,and voxel-based MRI morphometry for distinguishing between dementia with Lewy bodies and Alzheimer’s disease

Objective

This study aimed to compare the diagnostic value of ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, N-isopropyl-p[¹²³I]iodoamphetamine (IMP) brain perfusion single-photon emission computed tomography (SPECT), and brain magnetic resonance imaging (MRI) voxel-based morphometry (VBM) for the differentiation of dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD).

Methods

Thirty-five and 34 patients with probable DLB and probable AD, respectively, were enrolled. All patients underwent ¹²³I-MIBG myocardial scintigraphy, ¹²³I-IMP brain perfusion SPECT, and brain MRI. For ¹²³I-MIBG imaging, we calculated early and delayed heart-to-mediastinum (H/M) uptake ratios. Three-dimensional stereotactic surface projections (3D-SSP) were used to analyze the results of ¹²³I-IMP SPECT. VBM with statistical parametric mapping 8 plus diffeomorphic anatomical registration using exponentiated Lie algebra (DARTEL) was used to analyze the brain MRI data.

Results

The area under the receiver operating characteristic curves (AUC) for discriminating DLB and AD was highest (0.882) for the delayed H/M ratio on ¹²³I-MIBG scintigraphy. AUC for z-score measurement in the occipital lobe was 0.818 and that for the extent of gray matter (GM) atrophy in the whole brain was 0.788. AUC for the combination of 3D-SSP and VBM analysis was 0.836. The respective sensitivities and specificities for distinguishing DLB from AD were 97.1 and 100 % for the delayed H/M ratio using ¹²³I-MIBG scintigraphy; 88.6 and 73.5 % for the occipital lobe z-score using 3D-SSP analysis; 85.7 and 64.7 % for the extent of whole brain GM atrophy using voxel-based MRI morphometry; and 91.4 and 76.5 % for the combination of 3D-SSP analysis and VBM.

Conclusions

¹²³I-MIBG myocardial scintigraphy was superior to brain perfusion SPECT and brain MRI using an advanced statistical technique to differentiate DLB and AD.     

Simultaneous dual-isotope imaging based on an artificial neural network for evaluating myocardial perfusion and fatty acid metabolism

Background

We contrived a scatter correction method based on an artificial neural network (ANN) and applied it to the simultaneous evaluation of myocardial perfusion and fatty acid metabolism in single-photon emission computed tomography (SPECT).

Methods

The count data of three energy windows were used as inputs of the ANN. The count ratios of the estimated primary-to-total photons for ^99mTc and ¹²³I, which were used to reconstruct ^99mTc and ¹²³I images, were calculated using the ANN. In a phantom study, single- and dual-isotope imaging with ^99mTc/¹²³I and ²⁰¹Tl/¹²³I was performed by means of a cardiac phantom simulating patients with and without obesity. In a human study, five normal volunteers and ten patients with myocardial infarction underwent myocardial perfusion and fatty acid metabolism imaging with single and dual SPECT with combinations of ^99mTc-methoxyisobutylisonitrile/¹²³I-beta-methyl(p-iodophenyl)pentadecanoic acid (BMIPP) and ²⁰¹Tl/¹²³I-BMIPP as tracers.

Results

Technetium-99m yielded more homogeneous images than ²⁰¹Tl because of the lower degree of photon attenuation, especially in the condition of obese patients, resulting in clearer visualization of the perfusion-metabolism mismatch. Dual ^99mTc/¹²³I SPECT offered comparable images with single SPECT in assessing myocardial damage.

Conclusions

The method effectively separated ^99mTc and ¹²³I primary photons and proved applicable to ^99mTc/¹²³I dual-isotope myocardial SPECT.     

Diagnosis of dementia with Lewy bodies: diagnostic performance of combined 123I-IMP brain perfusion SPECT and 123I-MIBG myocardial scintigraphy

Objective

We assessed the value of combining ¹²³I-IMP brain perfusion SPECT and ¹²³I-MIBG myocardial scintigraphy for the discrimination of dementia with Lewy bodies (DLB) from other types of dementia.

Methods

We subjected 252 consecutive patients with clinically suspected DLB to both ¹²³I-IMP brain perfusion SPECT and ¹²³I-MIBG myocardial scintigraphy. Patients with Parkinson’s disease were included. The 252 patients were randomly assigned to an estimation (n = 152) or a validation group (n = 100). Using univariate analysis, we first analyzed the relationship between various variables and the presence or absence of DLB in estimation group and then proceeded to multivariate analysis to obtain a combined index that predicted the likelihood of DLB. The diagnostic value of the index was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC) with the cutoff value selected from the ROC curve. We then tested the predictive accuracy of the index in validation group.

Results

The combined index was an arithmetic expression that combined the age, early ¹²³I-MIBG heart-to-mediastinum uptake (E-H/M) ratio, and the parietal lobe hypoperfusion score. Values for the AUC of the combined index, the E-H/M ratio, the parietal lobe hypoperfusion score, and the patient age in validation group were 0.95, 0.90, 0.72, and 0.73, respectively. There was a significant difference in the AUC of the combined index among other indices (p < 0.05). The sensitivity, specificity, and accuracy of the combined index for a diagnosis of probable DLB in validation group were 88, 87, and 87 %, respectively.

Conclusions

The combinational diagnosis based on ¹²³I-IMP brain perfusion SPECT, ¹²³I-MIBG myocardial scintigraphy, and the patient age is a simple and reliable means for predicting probable DLB.     

Use of cardiac radionuclide imaging to identify patients at risk for arrhythmic sudden cardiac death

Sudden cardiac death (SCD) accounts for about ½ of all cardiovascular deaths, in most cases the result of a lethal ventricular arrhythmia. Patients considered at risk are often treated with an implantable cardiac defibrillator (ICD), but current criteria for device use, based largely on left ventricular ejection fraction (LVEF), leads to many patients receiving ICDs that they do not use, and many others not receiving ICDs but who suffer SCD. Thus, better methods of identifying patients at risk for SCD are needed, and radionuclide imaging offers much potential. Recent work has focused on imaging of cardiac autonomic innervation. ¹²³I-mIBG, a norepinephrine analog, is the tracer most studied, and a variety of positron emission tomographic tracers are also under investigation. Radionuclide autonomic imaging may identify at-risk patients with ischemic coronary artery disease, particularly following myocardial infarction and in the setting of hibernating myocardium. Most studies have been done in the setting of congestive heart failure (CHF), with a recent large multicenter study of patients with advanced disease, typically at high risk of SCD, showing that ¹²³I-mIBG can identify a low risk subgroup with an extremely low incidence of lethal ventricular arrhythmias and cardiac death, therefore, perhaps not requiring an ICD. Cardiac neuronal imaging has been shown to be better predictive of lethal arrhythmias/cardiac death than LVEF and New York Heart Association class, as well as various ECG parameters. Autonomic imaging will likely play an important role in the advancement of cardiac molecular imaging.     

Cardiac sympathetic denervation is not related to nigrostriatal degeneration in Parkinson’s disease

Aim

The aim of our study was to investigate the relationship between myocardial sympathetic degeneration and nigrostriatal impairment in patients affected by Parkinson’s disease (PD) by means of ¹²³I-metaiodobenzylguanidine (¹²³I MIBG) scintigraphy and N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-[¹²³I]iodophenyl)nortropane (¹²³I FP-CIT) scintigraphy.

Patients and methods

The study involved 37 patients with clinical diagnosis of PD (22 males and 15 females, mean age 62 years (±10), evaluated with ¹²³I FP-CIT single photon emission computed tomography (SPECT) followed by ¹²³I MIBG scintigraphy within 20 (±3) days. Early and delayed anterior chest images were acquired and the heart/mediastinum ratio (H/M ratio) was calculated. Furthermore, the population has been divided on the basis of the main clinical pattern to investigate the possible role of a tremor-dominant or an akinetic-dominant phenotype in this comparison.

Results

In PD population, there were no statistical relationships between early and delayed ¹²³I MIBG cardiac and ¹²³I FP-CIT striatal uptake in contralateral caudate (P > 0.05) and in contralateral putamen (P > 0.05) to the side mainly affected; no statistically significant relationships have been found at any level when considering ipsilateral striatum. We did not find statistically significant relationships when considering the single PD phenotypes.

Conclusions

The results of our study suggest that cardiac sympathetic system and nigrostriatal system are differently affected in PD. In particular, the sympathetic neurodegeneration rate is not related to nigrostriatal degeneration rate and vice versa in our series as detectable scintigraphically.     

Combination of 123I-metaiodobenzylguanidine scintigraphy and flow-mediated dilation for the detection of patients with coronary spastic angina

Background

This study evaluated the usefulness of cardiac sympathetic nerve activity, estimated by ¹²³I-MIBG scintigraphy, and endothelial function, estimated by flow-mediated dilation (FMD), in the detection of coronary spastic angina (CSA).

Methods and results

We compared 78 consecutive patients suspected of CSA with ten age-matched controls. On the basis of a spasm provocation test with acetylcholine, 53 patients were diagnosed as CSA and 25 patients were considered to have chest-pain syndrome (CPS). The total defect score (TDS) by delayed ¹²³I-MIBG scintigraphy was significantly higher in both patient groups than in controls (P < 0.05), and was significantly higher in CSA than in CPS patients (P = 0.02). The heart/mediastinum activity (H/M) ratio by delayed ¹²³I-MIBG scintigraphy and FMD were significantly lower in both patient groups than in controls (P < 0.05), and were lower in CSA than in CPS patients (P = 0.04). In receiver-operating curve analysis, the areas under the curve for TDS, H/M, and FMD were 0.78, 0.72, and 0.70, respectively. The combination of delayed ¹²³I-MIBG scintigraphy and FMD showed a higher diagnostic value than either method alone.

Conclusions

¹²³I-MIBG scintigraphy and FMD can distinguish CSA patients among patients complaining of chest pain at rest, with good sensitivity and specificity.     

Reproducibility of planar 123I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy in patients with heart failure

Purpose

Despite its high prognostic value, widespread clinical implementation of ¹²³I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy is hampered by a lack of validation and standardization. The purpose of this study was to assess the reliability of planar ¹²³I-MIBG myocardial scintigraphy in patients with heart failure (HF).

Methods

Planar myocardial MIBG images of 70 HF patients were analysed by two experienced and one inexperienced observer. The reproducibility of early and delayed heart-to-mediastinum (H/M) ratios, as well as washout rate (WR) calculated by two different methods, was assessed using the intraclass correlation coefficient (ICC) and the Bland-Altman analysis. In addition, a subanalysis in patients with a very low H/M ratio (delayed H/M ratio <1.4) was performed. The delayed H/M ratio was also assessed using fixed-size oval and circular cardiac regions of interest (ROI).

Results

Intra- and interobserver analyses and experienced versus inexperienced observer analysis showed excellent agreement for the measured early and delayed H/M ratios and WR on planar ¹²³I-MIBG images (the ICCs for the delayed H/M ratios were 0.98, 0.96 and 0.90, respectively). In addition, the WR without background correction resulted in higher reliability than the WR with background correction (the interobserver Bland-Altman 95?% limits of agreement were ?2.50 to 2.16 and ?10.10 to 10.14, respectively). Furthermore, the delayed H/M ratio measurements remained reliable in a subgroup of patients with a very low delayed H/M ratio (ICC 0.93 for the inter-observer analysis). Moreover, a fixed-size cardiac ROI could be used for the assessment of delayed H/M ratios, with good reliability of the measurement.

Conclusion

The present study showed a high reliability of planar ¹²³I-MIBG myocardial scintigraphy in HF patients, confirming that MIBG myocardial scintigraphy can be implemented easily for clinical risk stratification in HF.     

Doxorubicin-induced cardiac neurotoxicity: Study with iodine 123-labeled metaiodobenzylguanidine scintigraphy

Background

Iodine 123-labeled metaiodobenzylguanidine (¹²³I-MIBG) can be used to generate a scintigraphic image of the adrenergic nervous innervation of the heart.

Methods and Results

To test the hypothesis that doxorubicin may lead to damage of cardiac neurons, we examined 37 patients with various malignant neoplasms, 14 of whom were on therapy with doxorubicin. All patients were examined with ¹²³I-MIBG scintigraphy and radionuclide ventriculography. Cardiac ¹²³I-MIBG uptake was assessed by means of a heart to mediastinum activity ratio (H/M). Left ventricular ejection fraction was not different in patients with or without doxorubicin. In patients receiving doxorubicin, the H/M ratio was significantly lower (1.73±0.25 vs 2.13±0.25, p<0.001) and correlated with doxorubicin cumulative dose (r=?0.51, p<0.001). By using a H/M ratio of 1.73 as a cutoff point, ¹²³I-MIBG uptake was abnormal in none of the 23 patients not receiving and 6 of 14 patients receiving doxorubicin therapy (p<0.001). In 10 patients initially not receiving doxorubicin, ¹²³I-MIBG scintigraphy was repeated after receiving 236±47 mg/m² of doxorubicin. The H/M became abnormal in 3 of 10 patients, whereas the ejection fraction became abnormal in 2 of 10 patients.

Conclusion

¹²³I-MIBG cardiac uptake decreases in a doxorubicin dose-dependent way, indicating a cardiac adrenergic neurotoxic effect of doxorubicin. This phenomenon appears early and generally before deterioration of the ejection fraction.     

Perfusion and metabolic scintigraphy with <Superscript>123</Superscript>I-BMIPP in prognosis of cardiac resynchronization therapy in patients with dilated cardiomyopathy

Objective

The objective of the study was to investigate the left ventricular (LV) myocardial perfusion and metabolism in patients with idiopathic dilated cardiomyopathy (DCM) and to identify the scintigraphic predictors of the efficacy of cardiac resynchronization therapy (CRT).

Methods

The study comprised 63 patients with DCM and severe heart failure (NYHA class III–IV). Before CRT, all patients received gamma-scintigraphy with ^99mTc-methoxyisobutylisonitrile (^99mTc-MIBI) and with ¹²³I-β-methyl-iodophenyl pentadecanoic acid (¹²³I-BMIPP) for evaluation of myocardial perfusion and metabolism, respectively. Before and after 6 months of CRT, all patients underwent echocardiography study to assess cardiac hemodynamics.

Results

After 6 months of CRT, patients were divided into two groups: group 1 comprised responders in whom LV end systolic volume (LVESV) decreased by ≥15 % (n = 39); group 2 comprised non-responders in whom LVESV decreased by <15 % (n = 24). Before CRT, LV pumping function did not significantly differ between groups. Significant differences were found in the following preoperative scintigraphic parameters: myocardial perfusion defect size [7.4 % (5.9; 13.2) % and 11.8 (8.8; 16.2) %, p < 0.05] and metabolic defect size [7.4 (4.4; 14.7) % and 8.8 (8.8; 17.6) %, p < 0.05]. Metabolic scintigraphy showed greater diagnostic efficacy in determining the indications for CRT compared with perfusion scintigraphy [areas under the ROC curves (AUC) of 0.722 and 0.612, respectively]. The best metabolic defect size threshold value of 7.35 % predicted CRT efficacy with the sensitivity and specificity rates of 77.8 and 66.7 %, respectively.

Conclusion

Data of metabolic scintigraphy may be useful for the integrated prediction of CRT efficacy.

     

Significance of cardiac sympathetic nervous system abnormality for predicting vascular events in patients with idiopathic paroxysmal atrial fibrillation

Purpose

Neuronal system activity plays an important role for the prognosis of patients with atrial fibrillation (AF). Using ¹²³I metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy, we investigated whether a cardiac sympathetic nervous system (SNS) abnormality would be associated with an increased risk of vascular events in patients with paroxysmal AF.

Methods

¹²³I-MIBG scintigraphy was performed in 69 consecutive patients (67?±?13 years, 62% men) with paroxysmal AF who did not have structural heart disease. SNS integrity was assessed from the heart to mediastinum (H/M) ratio on delayed imaging. Serum concentration of C-reactive protein (CRP) was measured before ¹²³I-MIBG study.

Results

During a mean of 4.5?±?3.6 years follow-up, 19 patients had myocardial infarction, stroke or heart failure (range: 0.2–11.5 years). SNS abnormality (H/M ratio <2.7) and high CRP (≥0.3 mg/dl) were associated with the vascular events (58.3% in 14 of 24 patients with SNS abnormality vs 11.1% in 5 of 45 patients without SNS abnormality, p?<?0.0001, 52.4% in 11 of 21 patients with high CRP vs 16.7% in 8 of 48 patients without high CRP, p?<?0.0001). After adjustment for potential confounding variables such as age, left atrial dimension and left ventricular function, SNS abnormality was an independent predictor of vascular events with a hazard ratio of 4.1 [95% confidence interval (CI): 1.3–12.6, p?=?0.014]. Further, SNS abnormality had an incremental and additive prognostic power in combination with high CRP with an adjusted hazard ratio of 4.1 (95% CI: 1.5–10.9, p?=?0.006).

Conclusion

SNS abnormality is predictive of vascular events in patients with idiopathic paroxysmal AF.     

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

Purpose

Hospitalization in patients with systolic heart failure is associated with morbidity, mortality, and cost. Myocardial sympathetic innervation, imaged by ¹²³I-meta-iodobenzylguanidine (¹²³I-mIBG), has been associated with cardiac events in a recent multicenter study. The present analysis explored the relationship between ¹²³I-mIBG imaging findings and hospitalization.

Methods

Source documents from the ADMIRE-HF trial were reviewed to identify hospitalization events in patients with systolic heart failure following cardiac neuronal imaging using ¹²³I-mIBG. Time to hospitalization was analyzed with the Kaplan-Meier method and compared to the mIBG heart-to-mediastinum (H/M) ratio using multiple-failure Cox regression.

Results

During 1.4 years of median follow-up, 362 end-point hospitalizations occurred in 207 of 961 subjects, 79 % of whom had H/M ratio <1.6. Among subjects hospitalized for any cause, 88 % had H/M ratio <1.6 and subjects with H/M ratio <1.6 experienced hospitalization earlier than subjects with higher H/M ratios (log-rank p?=?0.003). After adjusting for elevated brain natriuretic peptide (BNP) and time since heart failure diagnosis, a low mIBG H/M ratio was associated with cardiac-related hospitalization (HR 1.48, 95 % CI 1.05 – 2.0; p?=?0.02).

Conclusion

The mIBG H/M ratio may risk-stratify patients with heart failure for cardiac-related hospitalization, especially when used in conjunction with BNP. Further studies are warranted to examine these relationships.     

Reduced cardiac 123I-metaiodobenzylguanidine uptake in patients with spinocerebellar ataxia type 2: a comparative study with Parkinson’s disease

Purpose

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder characterized by cerebellar ataxia, supranuclear ophthalmoplegia, and peripheral neuropathy. Autonomic nervous system dysfunction is often present. This study evaluated the cardiac sympathetic function in patients with SCA2 using ¹²³I-metaiodobenzylguanidine (MIBG) in comparison with patients with Parkinson’s disease (PD) and control subjects.

Methods

Nine patients with SCA2, nine patients with PD, and nine control subjects underwent ¹²³I-MIBG imaging studies from which early and late heart-to-mediastinum (H/M) ratios and myocardial washout rates were calculated.

Results

Early (F?=?12.3, p?<?0.0001) and late (F?=?16.8, p?<?0.0001) H/M ratios were significantly different among groups. In controls, early and late H/M ratios (2.2?±?0.12 and 2.1?±?0.20) were significantly higher than in patients with SCA2 (1.9?±?0.23 and 1.8?±?0.20, both p?<?0.05) and with patients with PD (1.7?±?0.29 and 1.4?±?0.35, both p?<?0.001). There was also a significant difference in washout rates among groups (F?=?11.7, p?<?0.0001). In controls the washout rate (19.9?±?9.6 %) was significantly lower (p?<?0.005) than in patients with PD (51.0?±?23.7 %), but not different from that in SCA2 patients (19.5?±?9.4 %). In SCA2 patients, in a multivariable linear regression analysis only the Scale for the Assessment and Rating of Ataxia score was independently associated with early H/M ratio (β?=??0.12, p?<?0.05).

Conclusion

¹²³I-MIBG myocardial scintigraphy demonstrated an impairment of cardiac sympathetic function in patients with SCA2, which was less marked than in PD patients. These results suggest that ¹²³I-MIBG cardiac imaging could become a useful tool for analysing the pathophysiology of SCA2.     

Efficacy of 99mTc-sestamibi SPECT/CT for minimally invasive parathyroidectomy: comparative study with 99mTc-sestamibi scintigraphy, SPECT, US and CT

Purpose

We evaluated the efficacy of ^99mTc-sestamibi SPECT/CT for planning minimally invasive parathyroidectomy (MIP), comparing with dual phase ^99mTc-sestamibi scintigraphy, ^99mTc-sestamibi SPECT and conventional imaging (US and CT).

Methods

Thirty-one patients (M:F?=?10:21, range 35?C78?years old) who showed high serum parathyroid hormone (intact PTH) level were included. ^99mTc-sestamibi scintigraphy was performed 15 and 150?min after injection of ^99mTc-sestamibi (555?MBq), and ^99mTc-sestamibi SPECT/CT was obtained just after the delayed scan. Comparison study between imaging modalities was done by patient-based and lesion location-based analysis. The location of the lesion was confirmed by the operative finding. An operation was performed in 24 patients. Seven patients had normal ^99mTc-sestamibi SPECT/CT, and followed for more than 6?months after SPECT/CT.

Results

Among 24 patients, parathyroid adenoma was detected in 19 patients and the other 5 had parathyroid hyperplasia (total 35 lesions). ^99mTc-sestamibi scintigraphy detected abnormal uptake in 15 patients with 24 lesions. Conventional imaging identified abnormal findings in 17 patients with 27 lesions. SPECT detected abnormal findings in 18 patients with 27 lesions. SPECT/CT identified abnormal findings in 24 patients with 35 lesions. SPECT/CT demonstrated 100?% sensitivity in a patient-based analysis. SPECT/CT exhibited significantly better sensitivity than ^99mTc-sestamibi scintigraphy, SPECT and conventional imaging (p?<?0.05). All lesion location was correctly identified to perform MIP. The final clinical diagnosis of 7 normal SPECT/CT patients was secondary hyperparathyroidism on 6?months follow-up.

Conclusions

We correctly identified the precise location of parathyroid adenomas or hyperplasia by ^99mTc-sestamibi SPECT/CT which was helpful to perform MIP.