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.     

Cardiac applications of 123I-mIBG imaging

Cardiac autonomic innervation plays a key role in maintaining hemodynamic and electrophysiologic harmony. Cardiac sympathetic function is adversely altered in many disease states, such as congestive heart failure, myocardial ischemia, and diabetes. (123)I-mIBG, a sympathetic neurotransmitter radionuclide analog, aids in the detection of sympathetic innervation abnormalities and can be imaged with planar and single-photon emission computed tomographic techniques. Cardiac (123)I-mIBG uptake can be assessed by the heart mediastinal ratio (H/M), tracer washout rate, and focal uptake defects. These parameters have been widely studied and shown to correlate strongly and independently with congestive heart failure progression, cardiac arrhythmias, cardiac death, and all-cause mortality. There is accumulating evidence that (123)I-mIBG imaging can help to monitor a patient's clinical course and response to therapy. The ability to predict potentially lethal ventricular arrhythmias promises to help more accurately select patients for implantable cardioverter defibrillators, limiting unnecessary devices and identifying additional patients at risk who do not meet current guidelines. (123)I-mIBG shows potential to help determine whether greater risk and usually more expensive ventricular assist device therapies or cardiac transplantation might be needed. Although more investigation in larger populations is needed to strengthen previous findings, cardiac (123)I-mIBG imaging shows promise as a new technique for recognizing and following potentially life-threatening cardiac conditions.     

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.     

123Ⅰ-间碘苄胍心脏神经显像的临床应用进展

心脏神经分布在心脏的功能中起决定性作用,很多心脏疾患常常会引起心脏自主神经功能的损害.123Ⅰ-间碘苄胍心脏神经显像是评定心脏自主神经功能的一种方法,它不仅可以评价各种心脏疾病状态下交感神经的损伤程度,决定是否植入机械装置、进行心脏移植或指导药物治疗等,而且可以在分子水平可视化及定量分析心肌的基本病变.     

Observer reproducibility of results from a low-dose 123I-metaiodobenzylguanidine cardiac imaging protocol in patients with heart failure

Purpose

Imaging of the cardiac autonomic system with ¹²³I-metaiodobenzylguanidine (MIBG) is useful in the evaluation of patients with a variety of cardiac conditions, including heart failure (HF), but few data are available about the reproducibility of this technique. We assessed the observer reproducibility of the results from a low-dose ¹²³I-MIBG cardiac imaging protocol in patients with HF.

Methods

A total of 74 patients (62 men, age 67?±?10 years) with HF and left ventricular systolic dysfunction (ejection fraction 31?±?7 %) underwent low-dose (111 MBq) planar and single-photon emission computed tomography (SPECT) ¹²³I-MIBG cardiac sympathetic imaging. The intraclass coefficient of correlation (ICC), Lin’s concordance correlation coefficient, and Bland-Altman analysis were used to evaluate the intraobserver and interobserver reproducibility of early and late heart-to-mediastinum (H/M) ratios and of defect scores on SPECT images. The κ statistic was used to evaluate the concordance rates for the identification of patients with a low H/M ratio (<1.60) on late planar imaging.

Results

The differences between measurements obtained twice by the same examiner and by two examiners were negligible for both early and late H/M ratios and for SPECT defect scores. These findings were confirmed by the results of Bland-Altman analysis, and ICC and Lin’s coefficient values were excellent (>0.90) for all measurements. For the identification of patients with a low H/M ratio, the κ values were 0.90 for intraobserver concordance and 0.83 for interobserver concordance.

Conclusion

The present study showed a high observer reproducibility of planar H/M ratios and SPECT defect scores using a low-dose ¹²³I-MIBG cardiac imaging protocol in patients with HF.     

Cardiac neurotransmission spect imaging

The sympathetic nervous system has great influence on cardiovascular physiology. Cardiac neurotransmission single photon emission computed tomography (SPECT) imaging allows in vivo noninvasive assessment of presynaptic reuptake and storage of neurotransmitters, which offers characterization of the cardiac neuronal function in different diseases of the heart and other altered metabolic or functional conditions. Therefore assessment of the integrity of cardiac sympathetic innervation may help in the diagnosis of these disorders, as well as in prognostication, and will result in better therapy and outcome. At present, the most widely available SPECT tracer by which to assess cardiac neurotransmission is metaiodobenzylguanidine labeled with iodine 123. This article focuses on reviewing the characteristics of cardiac SPECT imaging with I-123 metaiodobenzylguanidine and its role in the assessment of pathophysiologic changes during relevant clinical conditions.     

Cardiac sympathetic denervation from the early stage of Parkinson's disease: clinical and experimental studies with radiolabeled MIBG.

Autonomic disorder is not infrequent in patients with akinetic-rigid syndromes, including idiopathic Parkinson's disease. In the advanced stage of Parkinson's disease, abnormal blood pressure responses, such as orthostatic hypotension and abnormal circadian blood pressure rhythm, may occur. Few cases of reduced 123I-metaiodobenzylguanidine (MIBG) accumulation in the heart or limbs of Parkinson's disease patients have been reported. However, whether reduced accumulation is caused by damage to the postganglionic sympathetic nervous system or by central autonomic failure corresponding to abnormalities in blood pressure regulation is unknown. METHODS: We evaluated sympathetic denervation in 32 Parkinson's disease patients using 123I-MIBG cardiac scintigraphy and compared the findings with those for autonomic dysfunction detected by orthostatic hypotension and diurnal blood pressure variation. Cardiac 125I-MIBG accumulation was also determined in an experimental model of Parkinson's disease using mice pretreated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). RESULTS: Cardiac 123I-MIBG accumulation 15 min after injection and 4 h after injection was markedly reduced in the Parkinson's disease patients (heart-to-mediastinum ratio: 1.58 +/- 0.37 and 1.33 +/- 0.28, respectively) compared with 7 healthy volunteers (2.42 +/- 0.27 and 2.60 +/- 0.15, respectively). This reduction was observed even at the earlier stages of physical activity or disease duration and also in patients with normal blood pressure response and variation, indicating that the marked decrease in cardiac 123I-MIBG accumulation may be a special feature of Parkinson's disease. Pretreatment with a total dose of 100 mg/kg MPTP, which is the standard dose used to destroy the dopaminergic neurons in models of Parkinson's disease, significantly reduced cardiac 125I-MIBG accumulation in C57BL/6 mice. Interestingly, the reduction of 125I-MIBG accumulation was still significant when MPTP was reduced to 5 mg/kg. These findings indicated that the postganglionic sympathetic nerves may be damaged by MPTP or unknown toxic substrates in experimental or human Parkinson's disease during the early stage, because dopaminergic neurons and sympathetic nerves are substantially similar in their plasma membrane transporters. CONCLUSION: Cardiac scintigraphy with 123I-MIBG may be used as a new imaging approach in the diagnosis and characterization of akinetic-rigid syndromes, especially Parkinson's disease.     

Nuclear imaging in cardiac amyloidosis

Amyloidosis is a disease characterized by depositions of amyloid in organs and tissues. It can be localized (in just one organ) or systemic. Cardiac amyloidosis is a debilitating disease and can lead to arrhythmias, deterioration of heart function and even sudden death. We reviewed PubMed/Medline, without time constraints, on the different nuclear imaging modalities that are used to visualize myocardial amyloid involvement. Several SPECT tracers have been used for this purpose. The results with these tracers in the evaluation of myocardial amyloidosis and their mechanisms of action are described. Most clinical evidence was found for the use of ¹²³I-MIBG. Myocardial defects in MIBG activity seem to correlate well with impaired cardiac sympathetic nerve endings due to amyloid deposits. ¹²³I-MIBG is an attractive option for objective evaluation of cardiac sympathetic level and may play an important role in the indirect measurement of the effect of amyloid myocardial infiltration. Other, less sensitive, options are ^99mTc-aprotinin for imaging amyloid deposits and perhaps ^99mTc-labelled phosphate derivatives, especially in the differential diagnosis of the aetiology of cardiac amyloidosis. PET tracers, despite the advantage of absolute quantification and higher resolution, are not yet well evaluated for the study of cardiac amyloidosis. Because of these advantages, there is still the need for further research in this field.     

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

Background

Assessment 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.

Methods

54 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.

Results

Cardiac 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 R ²?=?0.36; delayed R ² =0.43) and myocardial wall (early R ²?=?0.28; delayed R ²?=?0.37). Lung washout was an explanatory variable of organ washout of the heart (heart R ²?=?0.38; myocardial wall R ²?=?0.33). In general, SPECT indices showed moderate-to-good correlations with the planar uptake (PCC 0.497-0.851).

Conclusion

By 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.     

Cardiac autonomic neuropathy in the diabetic patient: does 123I-MIBG imaging have a role to play in early diagnosis?

OBJECTIVES: In diabetes, extended adrenergic receptor stimulation with hyperglycemia and insulin deficiency is associated with cardiac autonomic dysfunction. Clinically evident diabetic cardiac autonomic neuropathy (CAN) is associated with a poor prognosis. Research studies indicate that autonomic function tests, which are traditionally used to diagnose diabetic CAN, are less sensitive than (123)I-metaiodobenzylguanidine (MIBG) imaging, particularly in the early stages of the disease. This established imaging technique makes use of the noradrenaline analog MIBG, which is radiolabeled with (123)I to assess the noradrenaline uptake-1 mechanism of the sympathetic nervous system. Although scintigraphic studies indicate that long-standing cardiac autonomic dysfunction is permanent, some authors have shown partial reversibility with early metabolic intervention. (123)I-MIBG imaging could therefore have an important clinical role to play in the early diagnosis and treatment monitoring of diabetic CAN. METHODS: A PubMed/MEDLINE Internet search was performed using MIBG, diabetes, and cardiac autonomic neuropathy as key words. CONCLUSION: The general expense of (123)I-MIBG imaging, together with the lack of commercial availability of this radiopharmaceutical in the United States, has limited the clinical use of this technique. As such, the clinical role of (123)I-MIBG imaging in the early diagnosis of diabetic CAN has yet to be validated and defined in most regions of the world, and further study is required.     

New horizons in cardiac innervation imaging: introduction of novel <Superscript>18</Superscript>F-labeled PET tracers

Cardiac sympathetic nervous activity can be uniquely visualized by non-invasive radionuclide imaging techniques due to the fast growing and widespread application of nuclear cardiology in the last few years. The norepinephrine analogue ¹²³I–meta-iodobenzylguanidine (¹²³I–MIBG) is a single photon emission computed tomography (SPECT) tracer for the clinical implementation of sympathetic nervous imaging for both diagnosis and prognosis of heart failure. Meanwhile, positron emission tomography (PET) imaging has become increasingly attractive because of its higher spatial and temporal resolution compared to SPECT, which allows regional functional and dynamic kinetic analysis. Nevertheless, wider use of cardiac sympathetic nervous PET imaging is still limited mainly due to the demand of costly on-site cyclotrons, which are required for the production of conventional ¹¹C-labeled (radiological half-life, 20 min) PET tracers. Most recently, more promising ¹⁸F-labeled (half-life, 110 min) PET radiopharmaceuticals targeting sympathetic nervous system have been introduced. These tracers optimize PET imaging and, by using delivery networks, cost less to produce. In this article, the latest advances of sympathetic nervous imaging using ¹⁸F-labeled radiotracers along with their possible applications are reviewed.     

Clinical usefulness of 123I-BMIPP myocardial SPECT in collagen disease

This study was designed to evaluate the clinical usefulness of 123I-BMIPP myocardial SPECT for detecting cardiac involvement in patients with collagen disease. We studied 12 patients with systemic lupus erythematosus (SLE), 8 with progressive systemic sclerosis (PSS), 6 with polymyositis/dermatomyositis (PM/DM) and 3 with allergic granulomatosis and angiitis (AGA). A 111 MBq of 123I-BMIPP was intravenously injected at rest, and SPECT images were obtained at 15 min after the injection. Seven of 12 SLE, 6 of 8 PSS, 3 of 6 PM/DM and all 3 AGA patients showed an abnormal tracer uptake. The left ventricular ejection fraction was inversely correlated with a BMIPP abnormality. The regional wall motion abnormality was reduced in regions with reduced tracer uptake. These findings suggest that 123I-BMIPP imaging could be useful for assessment of cardiac involvement in patients with collagen disease.     

Multi-modality imaging of cardiac amyloidosis: Contemporary update

Cardiac amyloidosis is a heterogeneous and challenging diagnostic disease with poor prognosis that is now being altered by introduction of new therapies. Echocardiography remains the first-line imaging tool, and when disease is suspected on echocardiography, cardiac magnetic resonance imaging and nuclear imaging play critical roles in the non-invasive diagnosis and evaluation of cardiac amyloidosis. Advances in multi-modality cardiac imaging allowing earlier diagnosis and initiation of novel therapies have significantly improved the outcomes in these patients. Cardiac imaging also plays important roles in the risk stratification of patients presenting with cardiac amyloidosis. In the current review, we provide a clinical and imaging focused update, and importantly outline the imaging protocols, diagnostic and prognostic utility of multimodality cardiac imaging in the assessment of cardiac amyloidosis.     

[<Superscript>123</Superscript>]FP-CIT SPECT scans initially rated as normal became abnormal over time in patients with probable dementia with Lewy bodies

Purpose

Decreased striatal dopamine transporter (DAT) binding on SPECT imaging is a strong biomarker for the diagnosis of dementia with Lewy bodies (DLB). There is still a lot of uncertainty about patients meeting the clinical criteria for probable DLB who have a normal DAT SPECT scan (DLB/S?). The aim of this study was to describe the clinical and imaging follow-up in these patients, and compare them to DLB patients with abnormal baseline scans (DLB/S+).

Methods

DLB patients who underwent DAT imaging ([¹²³I]FP-CIT SPECT) were selected from the Amsterdam Dementia Cohort. All [¹²³I]FP-CIT SPECT scans were evaluated independently by two nuclear medicine physicians and in patients with normal scans follow-up imaging was obtained. We matched DLB/S-? patients for age and disease duration to DLB/S+ patients and compared their clinical characteristics.

Results

Of 67 [¹²³I]FP-CIT SPECT scans, 7 (10.4?%) were rated as normal. In five DLB/S? patients, a second [¹²³I]FP-CIT SPECT was performed (after on average 1.5 years) and these scans were all abnormal. No significant differences in clinical characteristics were found at baseline. DLB/S? patients could be expected to have a better MMSE score after 1 year.

Conclusion

This study was the first to investigate DLB patients with the initial [¹²³I]FP-CIT SPECT scan rated as normal and subsequent scans during disease progression rated as abnormal. We hypothesize that DLB/S? scans could represent a relatively rare DLB subtype with possibly a different severity or spread of alpha-synuclein pathology (“neocortical predominant subtype”). In clinical practice, if an alternative diagnosis is not imminent in a DLB/S? patient, repeating [¹²³I]FP-CIT SPECT should be considered.

     

Prediction of functional recovery and prognosis in patients with acute myocardial infarction by123I-BMIPP and201Tl myocardial single photon emission computed tomography: A multicenter trial

¹²³I-BMIPP [15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid] was developed for metabolic imaging with SPECT. A multicenter collaborative study was conducted on a large patient series to determine whether¹²³I-BMIPP and²⁰¹Tl myocardial SPECT are of use in predicting the prognosis and ventricular function after acute myocardial infarction (AMI). Patients with uncomplicated first AMI underwent resting¹²³I-BMIPP and²⁰¹Tl myocardial SPECT in the subacute phase after the onset of AMI. Of these, 167 patients who had been followed up for an average of 22 months were retrospectively reviewed to predict serious cardiac events and recurrent ischemia. In addition, the association between changes in radionuclide parameters and recurrent ischemia was investigated in Subgroup A (58 patients) who had repeated SPECT in the chronic phase. Furthermore, prediction of the ejection fraction (EF) was investigated in Subgroup B (94 patients) and Subgroup C (76 patients) in whom left ventriculography was performed at the time of discharge and 90 days or more after the onset, respectively. The prognosis was generally favorable, with 4 cases of cardiac death (2%), 3 of heart failure (2%), 4 of nonfatal reMI (2%), and 25 of recurrent ischemia (15%). The results of Cox multivariate regression analysis revealed a high probability of serious cardiac events in patients who were elderly (p = 0.04), who had 90% or more residual stenosis of the infarct-related artery (p = 0.09), and who had a high BMIPP defect score (p = 0.17). There was a high probability of recurrent ischemia in elderly patients (p = 0.10) who had multi-vessel disease (p = 0.03), but no association was found with radionuclide parameters in the subacute phase. In Subgroup A, however, the probability of recurrent ischemia tended to be high in patients with a large mismatch score between¹²³I-BMIPP and²⁰¹Tl in the subacute to chronic phase. An important observation was that the extent of BMIPP defect was more strongly correlated with EF at the time of discharge and 90 days or more after the onset than the extent of Tl defect (r = ?0.60 vs. r = ?0.47, and r = ?0.53 vs. r = ?0.43, respectively). In addition, multiple regression analysis showed that parameters related to the BMIPP defect were also better predictive factors of EF both at the time of discharge and 90 days or more after the onset. In conclusion, resting¹²³I-BMIPP and²⁰¹Tl myocardial SPECT performed in the subacute phase of AMI were shown to be useful in predicting prognosis and ventricular function for patient management.     

Prognosis of hypertrophic cardiomyopathy: Assessment by123I-BMIPP (β-methyl-p-(123I)iodophenyI pentadecanoic acid) myocardial single photon emission computed tomography

¹²³I-BMIPP (β-methyl-iodophenyl pentadecanoic acid) has shown unique properties for potential use in assessing myocardial metabolism. Previous basic and clinical studies demonstrated that the disturbances of myocardial metabolism precede the occurrence of myocardial perfusion abnormalities by using²⁰¹Tl in hypertrophic myocardium. The present study was therefore undertaken to determine whether or not¹²³I-BMIPP myocardial SPECT is useful in predicting the prognosis of hypertrophic cardiomyopathy (HCM) in 65 patients in 6 facilities. There were 33 patients with non-obstructive HCM, 12 with obstructive HCM, 12 with apical HCM and 8 with dilated-phase HCM. Fasted patients at rest received an intravenous injection of 111 MBq of¹²³I-BMIPP. Twenty to thirty minutes later, myocardial SPECT was carried out. The BMIPP severity score (BMIPP SS) was evaluated semiquantitatively by using representative short axial SPECT images. We followed up the incidence of cardiac events for a mean period of 3.0 ± 0.6 years. Cardiac events occurred in 13 patients. Of these, 11 developed heart failure and 6 died (4 from heart failure and 2 from sudden death). The BMIPP SS in the dilated-phase HCM was significantly higher than that in the remaining HCM patients. The BMIPP SS for the survivors was significantly lower than that for the non-survivors. The BMIPP SS was particularly high in patients with fatal heart failure. Furthermore, there was a close negative correlation between the BMIPP SS and percent fractional shortening measured by echocardiography (r = ?0.49). Finally, the mortality over the three years increased according to the extent of the BMIPP SS. In conclusion, these results indicate that the BMIPP SS is useful in evaluating the severity of HCM. We conclude that¹²³I-BMIPP is a valuable metabolic tracer in predicting the outcome of HCM.     

Cardiac neurotransmission imaging.

Cardiac neurotransmission imaging with SPECT and PET allows in vivo assessment of presynaptic reuptake and neurotransmitter storage as well as of regional distribution and activity of postsynaptic receptors. In this way, the biochemical processes that occur during neurotransmission can be investigated in vivo at a micromolar level using radiolabeled neurotransmitters and receptor ligands. SPECT and PET of cardiac neurotransmission characterize myocardial neuronal function in primary cardioneuropathies, in which the heart has no significant structural abnormality, and in secondary cardioneuropathies caused by the metabolic and functional changes that take place in different diseases of the heart. In patients with heart failure, the assessment of sympathetic activity has important prognostic implications and will result in better therapy and outcome. In diabetic patients, scintigraphic techniques allow the detection of autonomic neuropathy in early stages of the disease. In conditions with a risk of sudden death, such as idiopathic ventricular tachycardia and arrhythmogenic right ventricular cardiomyopathy, PET and SPECT reveal altered neuronal function when no other structural abnormality is seen. In patients with ischemic heart disease, heart transplantation, drug-induced cardiotoxicity, and dysautonomias, assessment of neuronal function can help characterize the disease and improve prognostic stratification. Future directions include the development of tracers for new types of receptors, the targeting of second messenger molecules, and the early assessment of cardiac neurotransmission in genetically predisposed subjects for prevention and early treatment of heart failure.     

Compared to <Superscript>123</Superscript>I-MIBG SPECT/CT, <Superscript>18</Superscript>F-DOPA PET/CT provides accurate tumor extent in patients with extra-adrenal paraganglioma

Aim

The aim of this study was to compare the accuracy of ¹²³I-MIBG SPECT/CT with that of ¹⁸F-DOPA PET/CT for staging extra-adrenal paragangliomas (PGLs) using both functional and anatomical images (i.e., combined cross-sectional imaging) as the reference standards.

Methods

Three men and seven women (age range 26–73 years) with anatomical and/or histologically proven disease were included in this study. Three patients had either metastatic head-and-neck paragangliomas (HNPGLs) or multifocal PGL, and seven patients had nonmetastatic disease. Comparative evaluation included morphological imaging with CT, functional imaging with ¹⁸F-DOPA PET, and ¹²³I-MIBG imaging including SPECT/CT. Imaging results were analyzed on a per-patient and per-lesion basis.

Results

On a per-patient basis, ¹⁸F-DOPA PET’s detection rate for both nonmetastatic and metastatic/multifocal disease was 100%, whereas that of planar ¹²³I-MIBG imaging alone was 10.0% and that of ¹²³I-MIBG SPECT/CT was 20.0%. Overall, on a per-lesion basis, ¹⁸F-DOPA PET showed a sensitivity of 69.2% (McNemar p?<?0.001) compared with anatomical imaging. Sensitivity of planar ¹²³I-MIBG scintigraphy was 5.6%, and that of SPECT/CT was 11.1% (McNemar p?<?0.0001). Overall, ¹⁸F-DOPA PET identified 18 lesions, and anatomical imaging identified 26 lesions; planar ¹²³IMIBG imaging identified only 1 lesion, and SPECT/CT, 2 lesions.

Conclusion

¹⁸F-DOPA PET is more sensitive than is ¹²³I-MIBG imaging, including SPECT/CT, for staging HNPGL. Combined functional and anatomical imaging (PET/CT) is indicated to exclude metastatic disease in extra-adrenal PGL.

     

The effect of levodopa therapy on dopamine transporter SPECT imaging with 123I-FP-CIT in patients with Parkinson’s disease

Purpose The aim of this study was to evaluate, by means of ¹²³I-FP-CIT SPECT, the effect of chronic treatment with levodopa on striatal dopamine transporter (DAT) in patients with Parkinsons disease.Methods Fifteen patients under stable levodopa/carbidopa monotherapy were imaged twice: at baseline on medication and after at least 20 days of treatment wash-out. DAT levels were assessed from SPECT imaging for the entire striatum, the right and left striatum, the right and left putamen and the right and left caudate, as a ratio of regional brain activities using the formula: (striatal region of interest–occipital)/occipital.Results During levodopa wash-out, despite a worsening in patients clinical disability (H&Y mean stage 2.53±0.58 versus 1.73±0.45 on therapy, p<0.001), striatal ¹²³I-FP-CIT levels were not significantly different from those at baseline in any of the brain regions examined.Conclusion The results of this study suggest that levodopa does not affect ¹²³I-FP-CIT brain imaging and confirm that it is not necessary to withdraw this medication to measure DAT levels with SPECT.     

The possible role of nuclear imaging in assessment of the cardiac resynchronization therapy effectiveness in patients with moderate heart failure

Background

The aim of the study was to elucidate the role of nuclear medicine imaging in the selection of candidates for cardiac resynchronization therapy (CRT) and in the evaluation of CRT effectiveness

Methods

We studied 28 patients (19 male and 9 female) with dilated cardiomyopathy (DCM) and heart failure (HF). Before implantation of CRT device, all patients underwent SPECT with ^99mTc-MIBI at rest to evaluate the myocardial perfusion, ¹²³I-BMIPP to evaluate the myocardial metabolism, and gated cardiac blood-pool SPECT (GBPS) to assess the myocardial contractile function. Following CRT, all patients were examined with 99mTc-MIBI SPECT and GBPS 12 ± 3 months after the intervention.

Results

All patients after CRT were divided into three groups. The first group included 10 patients with LVEF increased by more than 10 % (hyperresponders), the 2nd group included 11 patients with an increase in EF of more than 5 % but less than 10 % (responders) and third group consisted of 7 males whose LVEF remained unchanged or worsened compared with pre-operative values (nonresponders). Prior to CRT, no statistically significant differences were found between groups in hemodynamic parameters (EF, EDV, ESV, SV), intra- and interventricular dyssynchrony, as well as in the midsize of perfusion defects. Following long-term CRT, we found increase in LVEF and decrease in average size of perfusion defects in groups of hyperresponders and responders (p < 0.05). Results of SPECT with ¹²³I-BMIPP, performed prior to CRT, showed that nonresponders had more pronounced disturbance of myocardial metabolism compared with the group of hyperresponders (20 vs. 14.7 %, p < 0.05).

Conclusion

The radionuclide methods can be used as possible indicators in the evaluation effectiveness and selection of candidates on the CRT.