Iodine-123 BMIPP scintigraphy in the evaluation of patients with heart failure

PURPOSE: To investigate whether cardiac parameters obtained by I-123 15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP, a radioactive fatty acid analogue) myocardial scintigraphy are useful as indicators of disease severity and predictors of cardiac events in congestive heart failure (CHF). MATERIAL AND METHODS: Thirty-two CHF patients (functional class: 17 in NYHA II and 15 in NYHA III at the time of this study) were compared with 18 normal control subjects. Myocardial scintigraphy was performed 15 min and 3 hours after I-123 BMIPP injection. The heart-to-mediastinum count ratio of I-123 BMIPP on the initial (H/Mi) and delayed (H/Md) images and the washout rate (WR) were calculated. RESULTS: Both H/Mi and H/Md were lower in CHF than in controls (H/Mi 1.96+/-0.18 vs. 2.30+/-0.29; H/Md 1.72+/-0.15 vs. 1.97+/-0.21; both P<0.001), but WR was higher in CHF than in controls (WR (%) 23.7+/-5.7 vs. 18.2+/-6.0, P<0.01). Both H/Mi (R = 0.42, P<0.05) and H/Md (R = 0.45, P<0.05) correlated positively with the left ventricular (LV) ejection fraction (EF), estimated by echocardiography. The WR correlated positively with the plasma B-type natriuretic peptide (BNP) level (R = 0.47, P<0.01). Kaplan-Meier analysis showed an earlier CHF progression for patients with a lower H/Mi (<1.94). CONCLUSION: Myocardial metabolic abnormality evaluated by I-123 BMIPP scintigraphy is related to the severity of CHF. Furthermore, it may be useful as a predictor for cardiac events.     

Segmental pattern of myocardial sympathetic denervation in idiopathic dilated cardiomyopathy: relationship to regional wall motion and myocardial perfusion abnormalities

BACKGROUND: Iodine 123-labeled metaiodobenzylguanidine (MIBG) has been used to study cardiac adrenergic nerve activity. Cardiac MIBG uptake is diminished in patients with heart failure. However, it is not known how this reduction is related to regional abnormalities of myocardial wall motion or perfusion. METHODS AND RESULTS: We studied 24 patients with idiopathic dilated cardiomyopathy (ejection fraction <45%) and 15 healthy control subjects using I-123 MIBG cardiac imaging, echocardiographic assessment of wall motion abnormalities, technetium 99m sestamibi perfusion scintigraphy, and hemodynamic assessment. Cardiac MIBG was significantly correlated with ejection fraction (r = 0.67), cardiac index (r = 0.57), left ventricular wall motion score index (r = -0.68), and systolic wall stress (r = -0.61). MIBG was lower in patients than in control subjects (1.43 +/- 0.19 vs 2.05 +/- 0.02; P <.01), whereas the washout rate was higher (P <.01). Moreover, a significant correlation was found between the reduction in MIBG uptake and the severity of echocardiographic wall motion abnormalities in the anterior wall (r = 0.543), apex (r = 0.530), and septum (r = 0.675), as well as with the severity of decrease in resting myocardial perfusion in the anterior wall (r = 0.480) and septum (r = 0.580). CONCLUSIONS: Patients with idiopathic dilated cardiomyopathy show not only global but also regional abnormalities of cardiac sympathetic innervation. The severity of these changes is partially correlated with abnormalities of regional wall motion and myocardial perfusion.     

I-123 MIBG and serial radionuclide angiocardiography in doxorubicin-related cardiotoxicity.

In six patients with doxorubicin-related cardiotoxicity, the severity of decrease in left ventricle ejection fraction (LVEF) was associated with faster myocardial I-123 MIBG washout rates. In four patients with severely decreased LVEF (range 19% to 28%), the 4-hour washout rate varied from 43% to 56%. In two patients with moderate cardiotoxicity (LVEF 42% and 43%), the washout rates were 37% and 35%, respectively. In contrast, in another patient thought to have initial left ventricular dysfunction (LVEF dropped from 66% to 54%), the myocardial I-123 MIBG retention rate was not reduced (6% washout). Subsequent continuation of chemotherapy in this patient was without complication. Reduced I-123 MIBG uptake in the left ventricle generally correlated with areas with abnormal Fourier amplitude values, but in one of the patients with moderate cardiotoxicity, the I-123 MIBG uptake was not reduced in a region with loss of amplitude, indicating dysfunction but probably no myocardial denervation. Analysis of the regional myocardial retention in patients with cardiotoxicity showed no significant difference in the I-123 MIBG washout rates of both segments with or without loss of amplitude. These data suggest that in spite of a localized loss of ventricular function demonstrated by radionuclide angiocardiography, doxorubicin-related cardiotoxicity appears to be based on a global process of myocardial adrenergic derangement.     

A study on the intrapulmonary kinetics of N-isopropyl-p-[I-123]-iodoamphetamine in patients with interstitial lung diseases--assessment of disease activity by dynamic scintigraphy and regional clearance curve

Aiming at clinical application of N-isopropyl-p-[I-123]-iodoamphetamine (I-123 IMP) to lung diseases intrapulmonary kinetics of I-123 IMP was studied. Dynamic lung scintigraphy was performed after intravenous injection of 3 MBq I-123 IMP in six normal volunteers and twenty patients with interstitial lung diseases. Simultaneously data were acquired in a data processor with 60-sec intervals over the period of 60 min. Time-activity curves of two areas of each lung field were obtained to calculate k values by monoexponential fitting method. In patients with interstitial lung diseases k values were significantly decreased (p less than 0.001) (0.995 X 10(-2) +/- 0.26 X 10(-2) as compared with those (1.602 X 10(-2) +/- 0.24 X 10(-2) in normal volunteers. For the assessment of capillary blood volume in the lung Tc-99m Sn colloids (SN) were given i.v. before I-123 IMP in 16 patients. There was a high correlation between regional uptake ratio of I-123 IMP and Tc-99m Sn colloids (SN) both at 1 min (n = 64; r = 0.91) and 25 min (n = 64; r = 0.93) after injection. The k values of IMP clearance curves were correlative to diffusing capacity at rest for CO (DLCO) (r = 0.71, p less than 0.01), vital capacity (r = 0.53, p less than 0.05) and forced expiratory volume in 1 sec (r = 0.58, p less than 0.05). These results suggest that the lung clearance of I-123 IMP reflect the severity of the endothelial cell injury which cause decrease in the capillary blood volume in interstitial lung diseases. Dynamic lung scintigraphy with I-123 IMP should prove useful for monitoring disease activity of interstitial lung diseases providing a new parameters to assess a non-respiratory lung function.     

Clinical value of lung uptake of iodine-123 metaiodobenzylguanidine (MIBG), a myocardial sympathetic nerve imaging agent, in patients with chronic heart failure

This study investigated the clinical value of I-123 MIBG pulmonary accumulation and washout in patients with chronic heart failure (CHF). Nineteen patients with CHF and 15 normal volunteers (NL) were included. The uptake ratio of heart to mediastinum (H/M), that of lung fields to mediastinum (L/M), and washout rate (WR) of the heart and lung fields were calculated in anterior planar images and compared with results of echocardiography and cardiac catheterization. In the CHF group, the lung uptake in delayed images increased and lung WR was decreased, suggesting pulmonary endothelial lesions. Furthermore, there was a negative correlation between right and left lung WR and pulmonary arterial diastolic pressure (PA(D)) and pulmonary arterial systolic pressure (PA(s)) in the CHF group. Since the WR of MIBG reflected PA, it may be used as an index of severity of cardiac dysfunction.     

Evaluation of hypertrophic cardiomyopathy with 123I-metaiodobenzylguanidine

Single-photon emission computed tomography was performed in 29 patients with hypertrophic cardiomyopathy (HCM) using 123I-metaiodobenzylguanidine (MIBG). Segmental myocardial uptake of MIBG and 201T1 was calculated in 21 patients with primary HCM without history of hypertension. Septal thickness was measured by echocardiography and the relationship to septal MIBG uptake was studied. Initial MIBG uptake and 201T1 uptake showed positive correlation with the septal thickness (R = 0.581, p = 0.0058 and R = 0.677, p = 0.0007). When the septal MIBG uptake was divided by the corresponding 201T1 uptake (MIBG/T1), both the early and delayed MIBG/T1 showed negative correlation with the septal thickness (R = -0.485, p = 0.0255 and R = -0.535, p = 0.0125). Significant positive correlation was observed between septal MIBG clearance and the thickness (R = 0.510, p = 0.0182). In patients with severe septal hypertrophy (greater than 20 mm), the MIBG clearance was significantly higher compared with less hypertrophic (less than or equal to 20 mm) group (13.4 +/- 8.0%/hr vs. 3.2 +/- 4.7%/hr, p = 0.0028). Thus, MIBG was useful for the evaluation of sympathetic innervation and activity in HCM. The MIBG clearance and uptake in conjunction with 201T1 study seemed to reflect the severity of hypertrophy in HCM.     

Abnormality of the myocardial sympathetic nervous system in a patient with Becker muscular dystrophy detected with iodine-123 metaiodobenzylguanidine scintigraphy.

PURPOSE: This study was performed to determine whether I-123 metaiodobenzylguanidine (MIBG) scintigraphy can depict myocardial sympathetic nerve abnormalities in Becker muscular dystrophy. MATERIALS AND METHODS: A 34-year-old man with Becker muscular dystrophy underwent Tl-201 and I-123 MIBG scintigraphy sequentially before and 4 months after the beginning of oral administration of enalapril maleate, an angiotensin-converting enzyme inhibitor. RESULTS: Before and during treatment, stress Tl-201 scintigraphy revealed nonreversible myocardial perfusion defects in the anterior, inferoposterior, and apical walls, and I-123 MIBG scintigraphy depicted a region with decreased sympathetic nerve function or innervation. Before treatment, the I-123 MIBG heart count- mediastinum count (H:M) ratio was 2.1 and the washout rate was 21% on delayed images obtained 4 hours after the injection of I-123 MIBG, indicating hyperactivity of the sympathetic nervous system in the myocardium. During treatment, the H:M ratio was 3.0 and the washout rate was 15%. CONCLUSION: With I-123 MIBG scintigraphy it is possible to evaluate an abnormality of the myocardial sympathetic nervous system and the efficacy of administration of an angiotensin-converting enzyme inhibitor in this disease.     

<Superscript>123</Superscript>I-BMIPP delayed scintigraphic imaging in patients with chronic heart failure

Objective  The objective of the present study was to clarify the ability of ¹²³I-beta-methyl-iodophenylpentadecanoic acid (¹²³I-BMIPP) to evaluate the heart-to-mediastinum (H/M) ratio and myocardial global washout rate (WR) in patients with chronic heart failure (CHF). Methods  The severity of CHF was evaluated on the basis of the New York Heart Association (NYHA) classification. Twenty patients with CHF (13 with idiopathic dilated cardiomyopathy and 7 with ischemic cardiomyopathy) and 11 age-matched controls underwent myocardial radionuclide imaging. Scintigraphic images were obtained from each participant at the early (30 min following radio-isotope injection) and late (4 h) phases using ¹²³I-BMIPP. The H/M ratio and WR were calculated from planar images. Concentrations of plasma brain natriuretic peptide (BNP) were measured prior to the scintigraphic study. Results  The ¹²³I-BMIPP uptake of early H/M and global WR did not significantly differ among groups, but uptake of delayed H/M was significantly lower in patients with NYHA class III than in controls (control 2.47 ± 0.39; class III 1.78 ± 0.28, P < 0.05). The uptake of delayed H/M and global WR correlated with plasma log BNP in all participants (r = −0.38, P < 0.05; 0.43, P < 0.05, respectively). Conclusions  These data suggest that ¹²³I-BMIPP uptake of delayed H/M enhances the image of CHF severity. The myocardial WR of ¹²³I-BMIPP also effectively depicted the severity of CHF.     

Iodine-123 MIBG imaging before treatment of heart failure with carvedilol to predict improvement of left ventricular function and exercise capacity

BACKGROUND. We examined whether cardiac sympathetic imaging with iodine-123 metaiodobenzylguanidine (MIBG) would predict improvement of left ventricular (LV) function and exercise capacity in patients with heart failure after treatment with carvedilol. METHODS AND RESULTS. Eighteen patients with heart failure and 5 control subjects underwent I-123 MIBG imaging. Heart-to-mediastinum ratios at 20 minutes and 3 hours and myocardial washout rates (WR) were measured. Of the 18 patients, 11 were randomized to receive carvedilol medication, whereas the remaining 7 received a placebo. Only the carvedilol group demonstrated a significant improvement in both heart failure functional class and LV ejection fraction (EF) 1 year after the start of medication. Within the carvedilol group, MIBG WR showed a significant inverse correlation with improvement in LVEF (rho = -0.74, P =.02). The diagnostic accuracy of WR for predicting EF response to carvedilol was 91%. WR also appeared to be inversely related to the peak oxygen consumption rate (rho = -0.65, P =.08), although this did not reach statistical significance. CONCLUSION. I-123 MIBG imaging appears useful in predicting which patients with heart failure are likely to show the most improvement in LV function and exercise capacity after carvedilol treatment. Further studies in this area appear to be warranted.     

Alternating myocardial sympathetic neural function of athlete's heart in professional cycle racers examined with iodine-123-MIBG myocardial scintigraphy

Myocardial sympathetic neural function in professional athletes who had the long-term tremendous cardiac load has not been fully investigated by myocardial iodine-123-metaiodobenzylguanidine (MIBG) uptake in comparison with power spectral analysis (PSA) in electrocardiography. Eleven male professional cycle racers and age-matched 11 male healthy volunteers were enrolled in this study. The low frequency components in the power spectral density (LF), the high frequency components in the power spectral density (HF), the LF/HF ratio and mean R-R interval were derived from PSA and time-domain analysis of heart rate variability in electrocardiography. The mean heart-to-mediastinum uptake ratio (H/M ratio) of the MIBG uptake, in professional cycle racers was significantly lower than that in healthy volunteers (p < 0.01) and HF power in professional cycle racers was significantly higher than that in healthy volunteers (p < 0.05). In the group of professional cycle racers, the H/M ratio showed a significant correlation with the R-R interval, as indices of parasympathetic nerve activity (r = 0.80, p < 0.01), but not with the LF/HF ratio as an index of sympathetic nerve activity. These results may indicate that parasympathetic nerve activity has an effect on MIBG uptake in a cyclist's heart.     

Influence of age and gender on iodine-123 MIBG kinetics in normal lung

Materials and Methods

Seventeen healthy volunteers and 14 patients with no cardiac or pulmonary disorders were included in this study (age range: 24 to 88 years, mean age 50.2 ± 17.6 years; 16 males, 15 females). Planar images were obtained 15 min (early) and 3 h (delayed) after injection of I-123 MIBG (111 MBq). Pulmonary uptake of I-123 MIBG was quantified based on the lung-to-mediastinum ratio (LMR) on early and delayed images. The lung clearance rate (LCR) was calculated from both the early and delayed images.

Results

Both early and delayed LMR values increased slightly, although they showed no significant correlations with age. There was a significant inverse correlation between LCR and age (r = ?0.57, p < 0.001). Neither LCR nor LMR differed significantly between male and female patients, but the mean age of the men was lower than that of the women.

Conclusions

Pulmonary I-123 MIBG kinetics may reflect age-dependent changes in NE metabolism. The effects of age should be taken into account when assessing pulmonary NE metabolism with I-123 MIBG.     

I-123 MIBG imaging and heart rate variability analysis to predict the need for an implantable cardioverter defibrillator

BACKGROUND: Iodine 123 metaiodobenzylguanidine (MIBG) imaging and heart rate variability (HRV) analysis were compared in patients with an implantable cardioverter defibrillator (ICD) who did and did not receive defibrillator discharges. Although the ICD has been shown to abort potentially fatal ventricular arrhythmias, identification of patients who most benefit from this device remains difficult. As the autonomic nervous system has been implicated in the genesis of these arrhythmias, we undertook a pilot study to evaluate local myocardial sympathetic innervation with the use of I-123 MIBG myocardial imaging, as well as central autonomic tone with the use of HRV, in patients with implantable defibrillators. Test results were correlated with the occurrence of ICD discharges. METHODS AND RESULTS: Seventeen patients with previously implanted defibrillators were studied. Of these, 10 had at least 1 appropriate device discharge for ventricular tachyarrhythmias, whereas 7 had no discharge. Patients with a discharge had a significantly lower I-123 MIBG heart-mediastinal tracer uptake ratio, higher I-123 MIBG defect scores, more extensive sympathetic denervation, and significantly reduced values for several HRV parameters, particularly those in the frequency domain. When combined, the I-123 MIBG heart-mediastinal ratio and HRV 5-minute low-frequency variables were highly predictive of defibrillator discharges. All patients with a heart-mediastinal ratio lower than 1.54 and 5-minute low frequency lower than 443 ms(2) had an ICD discharge (4/4), whereas no patient with an uptake ratio greater than 1.54 and 5-minute low frequency greater than 443 ms(2) did (0/3, P =.03). CONCLUSIONS: Cardiac autonomic assessment using a combination of myocardial scintigraphic and neurophysiologic techniques may help select patients who would most benefit from an implantable defibrillator by identifying those at increased risk for potentially fatal arrhythmias.     

Detection of denervated but viable myocardium in cardiac sarcoidosis with I-123 MIBG and Tl-201 SPECT imaging

A 58-year-old man, who had biopsy-proven cardiac sarcoidosis, underwent TI-201 and I-123 MIBG cardiac scintigraphy. Although no perfusion defect was identified by Tl-201, mild heterogeneity of I-123 MIBG uptake was present in the myocardium. The denervated but viable myocardium was demonstrated in the heart with sarcoidosis. Cardiac sympathetic nerve function was impaired in cardiac sarcoidosis, slightly improved with steroid therapy. I-123 MIBG scintigraphy may be useful to assess extent of myocardial involvement and response to therapy.     

Cardiac adrenergic innervation is affected in asymptomatic subjects with very early stage of coronary artery disease.

The aim of this study was to investigate whether, in subjects with a very early stage of coronary artery disease without hemodynamically significant coronary artery stenoses, cardiac adrenergic innervation is already affected. METHODS: Quantitative coronary angiography and dual-isotope SPECT with 123I-metaiodobenzylguanidine (MIBG) and 99mTc-sestamibi (MIBI) were conducted to assess the function of cardiac adrenergic innervation and myocardial perfusion, respectively, in 30 asymptomatic volunteers with a high familial risk for coronary artery disease. Regional quantitative analysis of MIBG uptake and washout rates was performed using the SPECT data from the anteroseptal, lateral, and inferior myocardial regions, which represented vascular supply by the left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX), and right coronary artery (RCA), respectively. RESULTS: The average severity of stenoses was 33% +/- 11% in the LAD, 29% +/- 14% in the LCX, and 26% +/- 19% in the RCA. The severity of stenosis was not related to MIBI uptake in any corresponding myocardial region at rest or during exercise. However, the degree of LAD stenosis correlated directly with delayed MIBG uptake (r = 0.43; P < 0.05) and inversely with MIBG washout (r = -0.34; P = 0.06) of the anteroseptal myocardium. When subjects were divided into tertiles according to the separate severity of stenosis for each coronary artery, delayed MIBG uptake in the anteroseptal region was significantly lower in the lowest LAD tertile (0.34 +/- 0.05) than in the middle (0.41 +/- 0.06; P < 0.01) or highest (0.43 +/- 0.05; P < 0.001) LAD tertile. Correspondingly, delayed MIBG uptake in the lateral region was also lower in the lowest LCX tertile than in the middle tertile (0.34 +/- 0.04 vs. 0.41 +/- 0.06, respectively; P < 0.01). Washout rate was also higher in the lowest LAD tertile (44% +/- 7%) than in the middle (36% +/- 10%; P < 0.05) or highest LAD tertile (34% +/- 8%; P < 0.01). CONCLUSION: The degree of coronary artery stenosis was associated directly with MIBG uptake and inversely with MIBG washout. This finding suggests that the function of cardiac adrenergic nerve endings is modified even in mild coronary artery disease before denervation occurs.     

Angiotensin-converting enzyme inhibition improves cardiac fatty acid metabolism in patients with congestive heart failure

This study aimed to examine whether angiotensin-converting enzyme (ACE) inhibition improved cardiac fatty acid metabolism in patients with congestive heart failure (CHF). Myocardial 123I-beta-methyl-iodophenylpentadecanoic acid (123I-BMIPP) imaging was performed in 25 patients with CHF and in 10 control subjects. Myocardial 123I-BMIPP images were obtained 30 min and 4 h after tracer injection. The heart-to-mediastinum (H/M) ratio of 123I-BMIPP uptake and the washout rate of 123I-BMIPP from the myocardium were calculated. Patients were given enalapril for 6 months, and 123I-BMIPP imaging was repeated. H/M ratios on early and delayed images were lower in CHF patients than in normal controls (P<0.01). The washout rate of 123I-BMIPP from the myocardium was faster in CHF patients than in controls (P<0.01). As the severity of the New York Heart Association (NYHA) functional class increased, the H/M ratio decreased and the washout rate increased. The washout rate of 123I-BMIPP was inversely correlated with left ventricular fractional shortening (R=-0.62, P<0.01). ACE inhibition with enalapril increased the H/M ratio on delayed images (P<0.05) and reduced the washout rate of 123I-BMIPP (P<0.05) in CHF patients. These data suggest that: (1) angiotensin II-mediated intracellular signalling activation may be a possible mechanism for the decreased myocardial uptake and enhanced washout of 123I-BMIPP in heart failure patients; and (2) the improvement in fatty acid metabolism by ACE inhibition may represent a new mechanism for the beneficial effect of this therapy in heart failure.     

Scintigraphic assessment of regional cardiac sympathetic nervous system in patients with single-vessel coronary artery disease

In coronary artery disease, the cardiac sympathetic nervous system is closely associated with myocardial ischemia. I-123 metaiodobenzylguanidine (MIBG) imaging allows us to assess the cardiac sympathetic nervous system regionally. One-hundred and eleven patients with single-vessel disease underwent regional quantitative analysis of MIBG imaging before successful percutaneous transluminal coronary angioplasty (PTCA), and repeat angiography 6 months after PTCA. Based on the results of the follow-up left ventriculogram, patients were divided into 3 groups: 39 angina pectoris (AP), 48 prior myocardial infarction without asynergy (MI without asynergy) and 24 prior myocardial infarction with asynergy (MI with asynergy). AP and MI without asynergy had significant correlations between uptake parameters and regional washout in the territory of diseased vessels, among which the severity score in AP was the most closely correlated with regional washout (r = 0.79, p < 0.0001). These correlations disappeared in MI with asynergy. To compare regional MIBG parameters in the territory of the diseased vessel as well as in the territories of the other major coronary arteries among the 3 groups, we examined MIBG parameters in 57 patients with left anterior descending artery (LAD) disease selected from among the study patients. Regional washout in the territory of the LAD was significantly higher in the MI without asynergy group than in the other two groups. The left circumflex artery (LCX) region showed significantly reduced MIBG uptake and an increased extent score in the MI with asynergy group compared with the AP group, although only a difference in the extent score existed between the MI with asynergy group and the AP group in the right coronary artery (RCA) region. In addition, the global ejection fraction before PTCA showed a significant negative correlation with each regional washout rate. In this way, regional quantitative analysis of MIBG imaging can detect the regional differences in the cardiac sympathetic nervous system in coronary artery disease, which may be associated with the degree of regional left ventricular dysfunction due to myocardial ischemia.     

Iodine-123 metaiodobenzylguanidine imaging of the heart in idiopathic congestive cardiomyopathy and cardiac transplants

Iodine-123 metaiodobenzylguanidine ([123I]MIBG) is a norepinephrine analog which can be used to image the sympathetic innervation of the heart. In this study, cardiac imaging with [123I]MIBG was performed in patients with idiopathic congestive cardiomyopathy and compared to normal controls. Initial uptake, half-time of tracer within the heart, and heart to lung ratios were all significantly reduced in patients compared to normals. Uptake in lungs, liver, salivary glands, and spleen was similar in controls and patients with cardiomyopathy indicating that decreased MIBG uptake was not a generalized abnormality in these patients. Iodine-123 MIBG imaging was also performed in cardiac transplant patients to determine cardiac nonneuronal uptake. Uptake in transplants was less than 10% of normals in the first 2 hr and nearly undetectable after 16 hr. The decreased uptake of MIBG suggests cardiac sympathetic nerve dysfunction while the rapid washout of MIBG from the heart suggests increased cardiac sympathetic nerve activity in idiopathic congestive cardiomyopathy.     

Scatter correction by two-window method standardizes cardiac I-123 MIBG uptake in various gamma camera systems

Heart to mediastinum count ratio (H/M) has been commonly utilized as an indicator of myocardial I-123 MIBG uptake. However, normal ranges of H/M were markedly different among various gamma camera systems. The purpose of this study was to clarify whether scatter correction by two-window method standardizes H/M among various gamma camera systems. METHODS: Scatter uncorrected and corrected MIBG imaging was acquired in phantom and human studies in combination with low energy high-resolution collimator (LEHR) and medium energy collimator (MEC). For scatter correction, energy window width of 159 keV +/- 10% was applied to main window imaging and 193 keV +/- 9.5% was applied to upper window imaging for scatter correction. RESULTS: In phantom study, a significant difference was observed in uncorrected H/M among three gamma camera systems using LEHR or MEC (2.09 +/- 0.06 vs. 2.58 +/- 0.03 in GCA7200 camera, 2.00 +/- 0.07 vs. 2.42 +/- 0.06 in DS7 camera and 2.16 +/- 0.04 vs. 2.67 +/- 0.07 in Vertex plus camera). However, there was no significant difference in corrected H/M among the three gamma camera systems, either with LEHR or MEC (2.70 +/- 0.07 vs. 2.69 +/- 0.07 in GCA7200 camera, 2.66 +/- 0.08 vs. 2.61 +/- 0.05 in DS7 camera and 2.66 +/- 0.05 vs. 2.61 +/- 0.05 in Vertex plus camera). In human study, uncorrected H/M in DS7 camera with LEHC was significantly lower than that in GCA7200 camera with MEC (1.60 +/- 0.37 vs. 1.85 +/- 0.54, N = 14). In contrast, the difference was insignificant in corrected H/M (2.12 +/- 0.59 vs. 2.16 +/- 0.68). There was a very excellent correlation in corrected H/M between DS7 and GCA7200 cameras (r = 0.991, p < 0.001). CONCLUSION: This study demonstrated that scatter correction by the two-window method standardizes the H/M in MIBG scintigraphy either with LEHR or MEC. Scatter corrected H/M can be applied to measure a standardized parameter of MIBG uptake in human clinical studies using various gamma camera systems.     

The reversibility of cardiac neuronal function after removal of a pheochromocytoma: an I-123 MIBG Scintigraphic Study.

PURPOSE: Twelve patients with proved pheochromocytoma evaluated in our institution between 1991 and 1997 are described. METHODS: The patients' urinary excretion rates and their metabolites (vanylmandelic acid and metanephrines) were significantly greater than normal before surgery. Echocardiography showed normal left ventricular ejection fractions (72% +/- 8%). All of the patients underwent planar I-123 metaiodobenzylguanidine (MIBG) scintigraphy to assess cardiac neuronal uptake 4 hours after and locate a pheochromocytoma 24 hours after intravenous injection of 185 MBq (3 mCi) I-231 MIBG. Ten patients with pheochromocytoma had positive tumoral findings with I-123 MIBG scintigraphy. Twelve patients had significant impairment of cardiac neuronal uptake of MIBG, with a heart:mediastinum ratio averaging 142% +/- 18% (normal value, 230% +/- 30%, P < 0.05). Postoperative cardiac MIBG imaging was performed in all patients (at 6 +/- 3 months). RESULTS: After surgical removal of the pheochromocytoma, cardiac MIBG uptake and the heart:mediastinum uptake ratios improved significantly (197% +/- 20%, P < 0.05) in all the patients. Urinary excretion rates and metabolites returned to the normal range. However, no significant correlation was found between cardiac MIBG uptake and urinary excretion rates and metabolites after the tumors were removed. CONCLUSION: Removing a pheochromocytoma reversed cardiac neuronal function as assessed by MIBG scintigraphy.     

Gallium-67 myocardial imaging for the detection of adriamycin cardiomyopathy

To detect Adriamycin cardiomyopathy, radionuclide myocardial imagings with Tl-201, Tc-99m pyrophosphate, I-123 metaiodobenzylguanidine and Ga-67 were performed in a 49 year-old-woman receiving Adriamycin (a total dose of 230 mg/m2) for the treatment of breast cancer. This patient demonstrated symptoms of congestive heart failure 2 months after the last intravenous administration. At the period of performing the radionuclide studies, echocardiographic LV ejection fraction (EF) was 22%. Despite severe deterioration of cardiac function, Tl-201 SPECT demonstrated no defect and Tc-99m pyrophosphate (PYP) SPECT demonstrated no positive finding. I-123 metaiodobenzylguanidine (MIBG) scintigraphy demonstrated no regional defect. However, I-123 MIBG washout rate during 4 hours was markedly enhanced, probably reflecting abnormalities of norepinephrine kinetics due to the progression of heart failure. Compared to these pharmaceuticals, Ga-67 was diffusely accumulated in the heart. Then, 5 months after the first study, when LV EF improved to 30% and congestive symptoms disappeared probably owing to beta-blockade therapy, myocardial accumulation of Ga-67 markedly reduced. It has been reported that Ga-67 accumulates in malignant tumor cells and leukocytes. Since, in Adriamycin cardiomyopathy, myocardial accumulation of leukocytes with myocardial fibrotic changes have been histologically demonstrated, the results of Ga-67 scintigraphy may reflect the accumulation of leukocytes. Thus, this case indicates that Ga-67 scintigraphy is advantageous for detecting Adriamycin cardiomyopathy and may be more useful than Tl-201 and Tc-99m PYP scintigraphies.