Regional Washout Rate Research Articles

Practice recommendation for measuring washout rates in 123I-BMIPP fatty acid images

The purpose of this practice recommendation is to specifically identify the critical steps involved in performing and interpreting 123I-β-methyl-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) and measurement of washout rate (WR) from the heart. This document will cover backgrounds, patient preparation, testing procedure, visual image interpretation, quantitation methods using planar and SPECT studies, and reporting of WR. The pitfall and some tips for the calculation of 123I-BMIPP WR are also included. The targets of global and regional WR calculation include ischemic heart disease, cardiomyopathy, heart failure, and triglyceride deposit cardiomyovasculopathy, an emerging rare heart disease.

Practice Recommendation for Measuring Washout Rates in 123I-BMIPP Fatty Acid Images.

The purpose of this practice recommendation is to specifically identify the critical steps involved in performing and interpreting 123I-β-methyl-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) and measurement of washout rate (WR) from the heart. This document will cover backgrounds, patient preparation, testing procedure, visual image interpretation, quantitation methods using planar and SPECT studies, and reporting of WR. The pitfall and some tips for the calculation of 123I-BMIPP WR are also included. The targets of global and regional WR calculation include ischemic heart disease, cardiomyopathy, heart failure, and triglyceride deposit cardiomyovasculopathy, an emerging rare heart disease.

Accuracy of washout rate analysis for thallium-201 single-photon emission computed tomography myocardial perfusion imaging using cadmium zinc telluride detectors: A phantom study.

ObjectiveThe aim of this study was to assess the accuracy of washout rate (WOR) analysis for thallium-201 chloride (201Tl) single-photon emission computed tomography myocardial perfusion imaging data acquired using cadmium zinc telluride detectors and a myocardial phantom.MethodsA myocardial phantom was injected with 10.5 MBq 201Tl, and 10-min acquisitions were performed at 0, 24, 46, and 62 h to accommodate natural radioactive decay over time. Global myocardial WOR (global-WOR) and regional WOR (regional-WOR, left anterior descending artery [LAD], right coronary artery [RCA], and left circumflex artery [LCX]) were analyzed between 0 and 24 h (infarction model), 0 and 46 h (ischemia model), and 0 and 62 h (normal model), respectively. We compared the calculated radioactive decay-rate as a reference standard and phantom imaging WOR (phantom-WOR).ResultsDecay-rate versus phantom-WOR were 20.4% vs. 20.8% (global-WOR), 21.3% (LAD), 21.2% (RCA), and 19.7% (LCX) for the infarction model; 35.4% vs. 35.6% (global-WOR), 35.5% (LAD), 36.2% (RCA), and 35.2% (LCX) for the ischemia model; and 44.5% vs. 45.1% (global-WOR), 45.4% (LAD), 44.7% (RCA), and 43.5% (LCX) for the normal model.ConclusionWOR analysis for 201Tl single-photon emission computed tomography myocardial perfusion imaging using cadmium zinc telluride detectors is a reliable analysis method.

Prediction of sudden cardiac death in patients with chronic heart failure by regional washout rate in cardiac MIBG SPECT imaging

BackgroundThe sympathetic nervous system provides an important trigger for major arrhythmic events through regional heterogeneity of sympathetic activity, which could be evaluated by SPECT imaging as the regional MIBG washout rate (WR). There is little information available on the prognostic value of regional WR in SPECT imaging for the prediction of sudden cardiac death (SCD) in patients with chronic heart failure (CHF). MethodsWe studied 73 CHF outpatients with LVEF < 40%. At study entry, the regional WR was measured in 17 segments on the polar map. We defined abnormal regional WR as both the regional WR range (maximum − minimum regional WR) and maximum regional WR > mean value + 2SD obtained in 15 normal controls. ResultsDuring a mean follow-up of 7.5 ± 4.1 years, 15 of 73 patients had SCD. The abnormal regional WR and abnormal global WR on planar images were significantly and independently associated with SCD. Patients with both the abnormal regional WR and global WR had a significantly higher risk of SCD than those with none of these criteria. ConclusionsThe analysis of regional MIBG WR on SPECT imaging provides additional prognostic value to global WR on planar images for SCD prediction in CHF patients.

Myocardial washout rate of resting 99mTc-Sestamibi (MIBI) uptake to differentiate between normal perfusion and severe three-vessel coronary artery disease documented with invasive coronary angiography

Patients with severe coronary artery disease (CAD) may present impaired mitochondrial function to enhance (99m)Tc-sestamibi (MIBI) washout from ischemic myocardium. In this study, we aimed to study the MIBI washout rate (WR) between patients with three-vessel CAD (3V-CAD) confirmed by invasive coronary angiography and healthy normal volunteers (HNV) to evaluate the potential utility of MIBI WR to differentiate between these two populations and to stratify the CAD severity. Ten HNV (male = 5, age = 56 ± 10 years) and eight 3V-CAD patients (male = 4, age = 62 ± 8 years) with 3V lumen stenosis ≥50% were enrolled for this study. Each study subject had a resting MIBI perfusion scan at 90 min and a repeated scan at 4 h post the MIBI injection. Global WR (GWR) and regional WR (RWR) were quantified with the percentage difference of decay-corrected polar maps obtained from the two scans and compared between the HNV and 3V-CAD groups. For the 3V-CAD group, the severity of CAD was assessed with CAD severity scores (CADSS) utilizing degree and location of obstructive lesions (stenosis ≥50%) for quantification and compared with WR to evaluate the correlation between these two variables. Significantly higher GWR was observed in the 3V-CAD (21.1 ± 4.6 %) group than the HNV group (9.5 ± 4.9%) (p < 0.001). RWR values in left anterior descending (LAD), right coronary artery (RCA) and left circumflex (LCX) in the 3V-CAD group were also higher than those of the HNV group (LAD 20.7 ± 5.9 vs 9.4 ± 5.6, p < 0.001; RCA 21.3 ± 4.8 vs 9.2 ± 5.8, p < 0.001; LCX 20.5 ± 7.2 vs 10.1 ± 4.4, p = 0.002). Additionally, the linear correlation of GWR and total CADSS for the whole myocardium was strong and statistically significant (y = 0.86x - 1.12, r (2) = 0.73, p = 0.006). Patients with impaired mitochondrial function due to 3V-CAD had consistently higher global and regional rest (99m)Tc-sestamibi washout rates than those of healthy normal volunteers. The global rest (99m)Tc-sestamibi washout rate is a sensitive indicator to stratify the severity of 3V-CAD and to differentiate between severe 3V-CAD and normal perfusion populations.

Direct correlation between regional systolic function and regional washout rate of 99mTc-sestamibi in patients with idiopathic dilated cardiomyopathy

Although a higher washout of ⁹⁹mTc-sestamibi (MIBI) from the ischemic myocardium was reported, little is known about it in idiopathic, nonischemic dilated cardiomyopathy (DCM). Using a quantitative electrocardiographic-gated single-photon emission computed tomography strategy, regional myocardial function may be obtained in conjunction with regional tracer perfusion. The aim of this study was to investigate the significance of regional washout of MIBI compared with regional systolic function in patients with DCM. Rest quantitative electrocardiographic-gated single-photon emission computed tomography was performed in 20 patients with DCM who had no significant coronary stenosis on coronary angiogram and in five normal volunteers. single-photon emission computed tomography imaging was observed at 30 min and 4 h after 740 MBq of MIBI injection, and the regional washout rate (WR) was calculated using a 20-segment model. The mean global ejection fraction was 28.2 ± 12.4% and the mean end-diastolic volume was 177 ± 78 ml. The myocardial segments were divided into three groups on the basis of the mean WR of normal volunteers: group A (n=164): WR ≥ 25.4% (=mean+SD); group B (n=138): 19.6% ≤ WR < 25.4%; group C (n=98): WR<19.6% (=mean-SD). The regional wall thickening of group A segments was significantly less than that of the other groups (11.6 ± 0.7 vs. 14.0 ± 0.9 and 14.9 ± 0.7%, respectively, P<0.05). The global left ventricular ejection fraction showed significant negative correlation to the extent of group A segments per patient (R=-0.65, P<0.005), indicating that higher washout was the result of decreased systolic function in DCM hearts. Regional higher WR of MIBI may indicate a significant marker for myocardial damage in asymptomatic to mildly symptomatic patients with DCM.

Myocardial washout rate of technetium-99m-sestamibi in the chronic phase predicts myocardial damage in patients with previous myocardial infarction

This study aimed to clarify the correlation between the myocardial washout rate (WR) of technetium-99m hexakis 2-methoxy-isobutyl-isonitrile ((99m)Tc-sestamibi) and cardiac enzyme levels in patients with acute myocardial infarction (AMI) 6 months after the onset. Sixty-one consecutive AMI patients (mean age, 66.2 ± 9.7 years) who underwent percutaneous coronary intervention (PCI) on admission were enrolled. Creatinine kinase MB isoenzyme (CK-MB) levels were measured every 3 h. (99m)Tc-sestamibi myocardial scintigraphic images were obtained at the early (30 min) and delayed (4 h) phases after tracer injection for calculating heart-to-mediastinum (H/M) ratios and global WRs at 2 weeks (0 M) and 6 months (6 M) after the onset of AMI. Regional WRs in the culprit lesions (culprit WR) and the extent score (ES) and severity score (SS) of myocardial damage were also calculated. PCI was performed 8.3 ± 7.7 h after AMI onset. At 6 M, the early H/M ratio (p = 0.04), delayed H/M ratio (p = 0.02), global WR (p = 0.01), culprit WR (p = 0.002), and delayed ES (p = 0.008) were alleviated. At 0 M, the peak CK-MB level correlated with the delayed H/M ratio (p = 0.003), global WR (p = 0.003), culprit WR (p < 0.001), early ES (p = 0.03), delayed ES (p = 0.01), early SS (p = 0.001), and delayed SS (p < 0.001). At 6 M, the peak CK-MB level correlated with the delayed H/M ratio (p < 0.001), global WR (p = 0.005), culprit WR (p = 0.001), early ES (p = 0.001), delayed ES (p < 0.001), early SS (p < 0.001), and delayed SS (p < 0.001). These results demonstrated that (99m)Tc-sestamibi WR in the chronic phase as well as that in the acute phase reflects the extent of initial myocardial damage in AMI patients after PCI. Moreover, it might indicate the myocardial condition in the clinical course.

Comparison of Global and Regional Abnormalities in 99mTc-sestamibi and Cardiac Magnetic Resonance Imaging in Dilated Cardiomyopathy

Objective The clinical relevance of perfusion defects and increased washout rate (WOR) in 99mTc-sestamibi (Tc MIBI) imaging has not been well characterized in dilated cardiomyopathy (DCM). We analyzed abnormalities in Tc MIBI imaging in relation to those in cardiac magnetic resonance (CMR) imaging. Methods and Results Nineteen DCM patients underwent both Tc MIBI and CMR imaging. The perfusion defects and global and regional MIBI WORs were evaluated with planar and single photon emission computed tomography (SPECT) images. The left ventricular function and the delayed enhancement (DE) were estimated with the cine- and DE-mode CMR. In the DCM patients, the Tc MIBI SPECT showed perfusion defects in 65 segments of 14 patients. The global and regional Tc MIBI WORs were higher than those in 10 normal volunteers (19.4 ± 9.1% vs. 11.7 ± 6.8% in global and 13.8 ± 8.6% vs. 9.6 ± 8.2% in regional WORs; mean ± SD, P < .01). The DE-mode CMR demonstrated DE in 103 segments of 14 patients. The severity of perfusion defects was correlated with the extent of DE ( r = 0.71, P < .01). The regional Tc MIBI WOR was highest in the segments with perfusion defects or DE, but the Tc MIBI WOR in segments without them was also higher than that in the normal volunteers. There was a weak but significant negative correlation between the regional Tc MIBI WOR and wall thickening ( r = −0.23, P < .01). Conclusions In DCM, the severity of perfusion defects and the increase in Tc MIBI WOR reflect the spread of myocardial fibrosis and/or scar. The increase in Tc MIBI WOR is potentially associated with regional dysfunction of LV wall.

Brain Natriuretic Peptide (BNP) Level is Closely Related to the Extent of Left Ventricular Sympathetic Overactivity in Chronic Ischemic Heart Failure

Both brain natriuretic peptide (BNP) and cardiac sympathetic activity are useful surrogate markers of congestive heart failure. BNP is known to be secreted in response to sympathetic tone. This study examined the relationship between the cardiac sympathetic system and BNP. Sixty patients with chronic ischemic heart failure (mean age,72 years-old; 46 males and 14 females) who had undergone cardiac catheterization and were classified as NYHA II underwent resting (99m)Tc-sestamibi quantitative gated imaging (MIBI) and (123)I-metaiodobenzylguanidine imaging (MIBG). MIBI was used to obtain left ventricular (LV) dimension. MIBG was used to obtain the washout rate and the H/M ratios as well as the extent of LV washout rate abnormality (RSNA), which was defined as the number of regions with a regional washout rate of more than mean+2SD of 15 normal subjects on a two-dimensional polar map divided into 20 regions. Blood samples were obtained to measure neurohormones such as BNP, renin activity, noradrenaline, and angiotensin II. Simple linear regression analysis showed that BNP had significant correlations to age, LVEF, LV end diastolic volume, LV end systolic volume, RSNA, global washout rate, myocardial ischemia, and LV end diastolic pressure. Among them, multiple linear regression analysis showed that only RSNA (partial regression coefficient =0.618, p<0.002) had a significant positive correlation with BNP. This study suggested that the extent of cardiac sympathetic overactivity in the LV could enhance BNP release.

Evaluation of cardiac sympathetic nerve activity and left ventricular remodelling in patients with dilated cardiomyopathy on the treatment containing carvedilol

It has been reported that carvedilol improves cardiac sympathetic nerve activity (CSNA) in patients with dilated cardiomyopathy (DCM). However, the influence of carvedilol on cardiac (123)I-meta-iodobenzylguanidine (MIBG) scintigraphic findings and left ventricular (LV) remodelling has not been determined in DCM patients. In 30 patients with DCM and 10 normal controls, the delayed heart/mediastinum count (H/M) ratio, delayed total defect score (TDS), and washout rate (WR) were determined by (123)I-MIBG scintigraphy. In addition, the left ventricular end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV ejection fraction (LVEF) were calculated by echocardiography. In the DCM patients, the regional defect score index (RDSI), regional washout rate index (RWRI), and wall motion score index (WMSI) were also determined to evaluate regional adrenergic dysfunction and wall motion. Examinations were repeated in all DCM patients after standard treatment containing carvedilol at a dose of 10-20 mg/day (mean dose: 16 +/- 4 mg/day) for a mean of 12 +/- 1 months. Both the (123)I-MIBG scintigraphic and echocardiographic parameters were significantly worse in the DCM patients than the normal control subjects. After treatment, all of these parameters improved significantly in the DCM patients. There was a significant correlation between the changes of (123)I-MIBG findings and changes of the LVEDV and LVESV after treatment. Moreover, there was a significant correlation between changes of the WMSI and those of the RDSI or RWRI in DCM patients. Both (123)I-MIBG scintigraphic parameters and echocardiographic parameters were improved in the DCM patients. There was a significant correlation between the changes of (123)I-MIBG scintigraphic and echocardiographic findings after treatment. These findings implicate that long-term, including carvedilol, therapy can improve both CSNA and LV remodelling in patients with DCM.

Reverse redistribution phenomenon on rest (99m)Tc-tetrofosmin myocardial single photon emission computed tomography involves impaired left ventricular contraction in patients with acute myocardial infarction.

The purpose of this study was to investigate the clinical significance of the reverse redistribution (RR) phenomenon on technetium-99m ((99m)Tc)-tetrofosmin myocardial single photon emission computed tomography (SPECT) performed at rest. Twenty-five patients underwent myocardial SPECT 3 weeks after the onset of acute myocardial infarction. Myocardial images were acquired at 40 min (early) and 4 h (delayed) after the injection of 740 MBq of (99m)Tc-tetrofosmin. The regional myocardial uptake of the tracer in 26 segments of the left ventricular (LV) wall was visually scored from 0 (no activity) to 3 (normal activity), and then the RR was defined as a decrease of more than 1 point in the activity score on the delayed image compared with that on the early image. Regions with an activity score of 3 on both the early and delayed images were defined as normal, and those with a score of 0 or 1 on the early image were considered to have a fixed defect. The regional myocardial (99m)Tc-tetrofosmin uptake and washout rate were also quantitatively assessed in each region. In addition, exercise stress electrocardiograph-gated SPECT with (99m)Tc-tetrofosmin was performed within 1 week of the rest study, and the percent count increase (%CI) during myocardial contraction in each corresponding region was studied. RR was observed in 18 of the 25 patients. The regional washout rate of (99m)Tc-tetrofosmin was significantly higher in the RR regions (45.0+/-3.8%) than in either the normal regions (36.4+/-4.1%, p<0.001) or in those with a fixed defect (39.7+/-3.9%, p<0.001). The %CI in the RR regions (10.4+/-10.4%) was significantly less than that in the normal regions (23.5+/-10.1%, p<0.001); however, no significant difference was found between the RR regions and those with a fixed defect (8.0+/-7.2%). In patients with acute myocardial infarction, the regions showing the RR phenomenon on (99m)Tc-tetrofosmin SPECT have severely impaired LV wall contraction after exercise.

Relationship between cardiac sympathetic function and baroreceptor sensitivity after acute myocardial infarction.

The relationship between baroreceptor sensitivity (BRS) and cardiac sympathetic nerve function after acute myocardial infarction (AMI) was investigated in 34 patients. BRS was measured during the Valsalva maneuver and cardiac sympathetic function was assessed by the washout rate (WR) of I-123 meta-iodo-benzyl guanidine (123I-MIBG) with planar image (global WR) and polar map analysis (regional WR). Gated left ventricular ejection fraction (LVEF) measured by left ventriculography as a parameter of ventricular function was measured with quantitative gated SPECT (QGS). The gated LVEF correlated with global WR (r=-0.36, p=0.034) and regional WR of normal area (r=-0.46, p=0.006), but not with BRS, although BRS correlated with global WR (r=-0.43, p=0.015) and regional WR of normal area (r=-0.72, p<0.0001). After AMI, baroreceptor function is linked to sympathetic activation, as elucidated by the regional WR of normal area, which suggests that separation of the infarcted area from the non-infarcted myocardium is necessary for evaluating sympathetic activation after AMI and that the regional kinetics of 123I-MIBG in the normal area are a more suitable marker of activated cardiac nerve function than global 123I-MIBG kinetics.

Assessment of the severity of coronary artery stenosis by the ratio of the regional washout rate determined by adenosine triphosphate stress TI-201 SPECT

Background. Adenosine triphosphate stress thallium-201 single-photon emission computed tomography (ATP SPECT) is useful for diagnosis of coronary artery disease, but its usefulness for evaluating the severity of coronary artery stenosis has not been established. Methods and Results. We performed region-of-interest analysis of short-axis images obtained by ATP SPECT in 31 patients with single-vessel disease (>50% stenosis of the luminal diameter). We selected the lowest and highest washout rates (WR) among the anterior, lateral, and inferior WRs and calculated the ratio of the lowest WR to the highest WR (WR ratio = 0.925 ± 0.027 in 14 control subjects). ATP SPECT showed positive results in 29 (94%) of 31 patients. The severity of coronary artery stenosis was inversely correlated with the WR ratio (r = −0.703, P < .0001). The sensitivity and specificity of a WR ratio ≤ 0.660 for the diagnosis of severe coronary stenosis (≥80% stenosis) were 83% and 80%, respectively. Conclusions. Results suggest that ATP SPECT may be useful for assessment of the severity of coronary artery stenosis in patients with single-vessel disease.

Evaluation of regional cardiac sympathetic innervation in congenital long QT syndrome using 123I-MIBG scintigraphy.

The aim of this study was to determine whether sympathetic imbalance in congenital long QT syndrome (LQTS) can be identified by cardiac sympathetic neuronal dysinnervation. 123I-metaiodobenzylguanidine (MIBG) is a tracer of the norepinephrine analogue which reflects the regional innervation and norepinephrine kinetics in cardiac sympathetic nerves. Sixteen patients with LQTS, who were members of 12 families, and 7 normal controls underwent MIBG scintigraphy. Myocardial SPET and planar images were obtained 15 min and 4 h after the injection of MIBG in each patient. The relative regional uptake (RRU) and regional washout rate (rWR) of MIBG at 4 h in each of nine regions were compared with those in the control group. The heat-to-mediastinum ratio (H/M) and global washout rate (GWR) were also calculated. The RRU, rWR, H/M and GWR showed no significant difference between LQTS patients and normal controls. Furthermore, the RRU in 96% of all regions in LQTS was within the mean +/- 2 standard deviations of that in the control group. Patients with LQTS have normal cardiac sympathetic innervation, as assessed by MIBG. The sympathetic imbalance hypothesis is unlikely to be attributed to an abnormal distribution and different regional norepinephrine kinetics of cardiac sympathetic nerves.

Iodine-123 Metaiodobenzylguanidine Cardiac Imaging to Identify and Localize Vasospastic Angina Without Significant Coronary Artery Narrowing

Objectives. We assessed the ability of iodine-123 metaiodobenzylguanidine (MIBG) imaging to identify and localize coronary spasm and determined the most useful method of MIBG analysis in vasospastic angina without significant coronary narrowing.Background. Various noninvasive methods have been used to detect vasospastic angina, but they are not very sensitive in patients with sporadic attacks. MIBG imaging has recently been proposed as a useful tool for detecting vasospastic angina.Methods. Normal limits of both visual and quantitative analysis of two-dimensional polar maps (bull’s-eyes) for MIBG imaging were at first established in 59 normal subjects. For optimal criteria of visual analysis, we established regional differences in abnormal MIBG defect scores. An abnormal region of the bull’s-eye was defined as an area >2 SD below normal. An abnormal regional washout rate was defined as <0%. Using these criteria, we prospectively evaluated 104 patients with suspected vasospastic angina. Visual, bull’s-eye and regional washout rate analyses were compared for overall detection of the disease and for individual vessel involvement.Results. Overall sensitivity by these methods was 30%, 42% and 76%, respectively. Washout rate analysis showed a significantly higher sensitivity than the other two methods. Specificity was 78%, 72% and 87%, respectively. The sensitivity of detecting spasm-induced coronary artery with washout rate analysis was 82% for the left anterior descending (LAD), 76% for the right (RCA) and 69% for the circumflex (Cx) coronary arteries. The sensitivity of visual analysis was 29%, 15% and 35%, respectively; that for bull’s-eye analysis was 34%, 54% and 41%, respectively. Washout rate analysis showed a significantly higher sensitivity for LAD spasm than for the other two methods and a higher sensitivity for RCA and Cx spasms than for visual analysis.Conclusions. Regional washout rate analysis of MIBG imaging is a highly accurate technique for determining the presence and location of coronary artery spasm.

Use of iodine-123 metaiodobenzylguanidine myocardial imaging to predict the effectiveness of beta-blocker therapy in patients with dilated cardiomyopathy.

It is crucial to predict drug effectiveness in chronic disease, such as dilated cardiomyopathy (DCM), in which the left ventricular (LV) function might be improved by beta-blocker therapy. As the functional improvement effected by beta-blocker therapy takes more than 2 months, we investigated whether iodine-123 metaiodobenzylguanidine (123I-MIBG) imaging could be used to predict drug effectiveness. We studied 13 patients (11 men and two women; mean age, 43+/-13 years) with DCM and seven normal subjects (six men and one woman; mean age, 48+/-16 years). We obtained myocardial single-photon emission tomography (SPET) images 15 min and 4 h after administration of 123I-MIBG (111 MBq). Studies were performed in the patients with DCM before and 1 and 3 months after the administration of metoprolol and in the normal subjects. We calculated the regional 123I-MIBG washout rate (r-WR) in the SPET image, and the global 123I-MIBG washout rate (g-WR) and heart-mediastinum activity ratio (H/M) using the anterior planar image. We classified patients into those showing a >/=5% increase in LV ejection fraction (LVEF) at 3 months compared with LVEF values before the treatment (group I, n=7) and those showing a <5% increase in LVEF (group II, n=6). In group I, the r-WR values at pretreatment and at 1 month and 3 months of treatment, respectively, were 36%+/-19%, 29%+/-14%* and 25%+/-13%* in the anterior segment, 39%+/-17%, 33%+/- 17%** and 28%+/-17%* in the lateral segment, 36%+/- 16%, 31%+/-14%* and 22%+/-12%** in the septal segment and 40%+/-11%, 37%+/-19% and 31%+/-18%* in the inferior segment; the g-WR was 45%+/-11%, 43%+/-10% and 34%+/-9%*, respectively (* P<0.05, ** P<0.01 vs pretreatment). In group II, there were no significant changes in regional or global parameters during the 3-month period. In normal subjects, the r-WR values in each of the anterior, lateral, septal and inferior segments were significantly lower than those in groups I and II. These values were 18%+/-9%, 18%+/-15%, 20%+/-12% and 21%+/-15%, respectively. This study demonstrated that with regional assessment 123I-MIBG SPET imaging can be used to predict the functional improvement of LVEF at 1 month of beta-blocker therapy in patients with DCM.

Assessment of regional sympathetic nerve activity in vasospastic angina: Analysis of iodine 123–labeled metaiodobenzylguanidine scintigraphy

With the use of iodine 123–labeled metaiodobenzylguanidine ( 123 I-MIBG) scintigraphy, this study evaluated regional sympathetic nerve activity in vasospastic angina. Twenty male patients with left anterior descending coronary artery spasm and 18 male patients with normal coronary arteries as a control group were studied. All patients underwent quantitative 123 I-MIBG scintigraphy and atropine stress 123 I-MIBG scintigraphy. Both groups showed a similar heterogeneous 123 I-MIBG uptake in the left ventricle. However, the regional washout rate in patients with coronary artery spasm was significantly reduced in all three territories compared with that in the control group. In vasospastic angina, the regional washout rate in the left anterior descending coronary artery territory was significantly reduced as compared with the other two regions. After intravenous injection of 1 mg atropine, the regional washout rate in the three regions significantly increased in both groups, but the regional differences between the two groups disappeared. The current study demonstrated that cardiac sympathetic nerve activity in vasospastic angina was suppressed, especially in the territory of the spasm-induced coronary artery, probably because of the enhanced parasympathetic nerve activity. (Am Heart J 1997;133:484-9.)

Sympathetic nerve activity in the spasm-induced coronary artery region is associated with disease activity of vasospastic angina

We assessed the relation between sympathetic nerve activity and disease activity of vasospastic angina. The autonomic nervous system has been proposed to play a key role in attacks of vasospastic angina. A unique feature of vasospastic angina attacks is periodic fluctuation, which complicates the assessment of disease activity. Twenty-five patients with left anterior descending coronary artery (LAD) spasm were studied: 12 with recent onset of chest pain (group 1) and 13 free of angina for more than 3 months after discontinuing medication (group 2). Group 1 underwent iodine-123 metaiodobenzylguanidine (MIBG) imaging (in the active phase) and atropine-stress MIBG imaging early after diagnostic angiography, and repeat MIBG imaging when they were free of angina for more than 3 months with medication (in the stable phase). Group 2 also underwent MIBG imaging (in remission). On a bull's-eye map, quantitative analysis of percent uptake and washout rate of MIBG was performed regionally. In group 1 in the active phase, the washout rate of the LAD territory was significantly lower than the rates in the stable phase, in remission and during atropine-stress MIBG imaging. The regional washout rate of the territories of the right coronary artery and the circumflex artery in the active phase was also significantly lower than that during atropine-stress MIBG imaging. The washout rate of the LAD territory in the active phase was significantly lower than the rates of the other two regions. In contrast, there were no significant differences in the distribution of regional percent uptake in every image. A similar distribution of washout rate was observed among group 1 patients in the stable phase, in group 1 patients during atropine-stress MIBG imaging and in group 2 patients. The MIBG washout rate of the spasm-induced coronary artery territory changed according to the degree of disease activity. Thus, sympathetic nerve activity could reflect disease activity of vasospastic angina.

Selective drug-induced reduction of blood flow in tumor transplants

The effect of a calcium antagonist and a physiologic amine on tumor and muscle perfusion was investigated with the aim of improving the preconditions for external hyperthermia treatment of cancer. Nisoldipine (0.04–4.0 mg/kg) and 5-hydroxy tryptamine (5-HT) (0.2–8.0 mg/kg) were administered i.p. in Sprague-Dawley rats bearing Walker 256 carcinoma, Yoshida sarcoma, or a homologous tumor transplant derived from a spontaneous leiomyosarcoma of the uterus. At the maximum dosage used, nisoldipine injection caused a decrease of the regional washout rate of Xenon-133 of 63 ± 8% (SEM) in the Walker carcinoma and an increase of 80 ± 41% in the muscle of the hind leg. 5-HT (8 mg/kg) caused a drop of 79 ± 29% in the Walker carcinoma and only a slight fall of the washout rate in muscle of 14 ± 4.8%. Tumor-to-muscle uptake ratios of 11C-butanol fell from 5.63 ± 1.98 to 3.32 ± 1.21, and from 5.3 ± 0.56 to 2.98 ± 0.30, after injection of 0.2 mg/kg nisoldipine and 4 mg/kg 5-HT, respectively. Similar reaction patterns and percentage changes were observed in different tumor lines at constant doses of 0.2 mg/kg nisoldipine and 4 mg/kg 5-HT. Both drugs representing two different rationales of vasomotor action were able to reduce blood flow specifically in transplanted tumors; nisoldipine increased muscle blood flow and decreased arterial blood pressure, whereas 5-HT acted without substantial systemic effects.

Imaging methods in the transmission computed tomographic measurement of regional xenon kinetics in the brain.

The process of an investigation of transmission computed tomographic measurements of the kinetics of stable xenon in the brain is reported. The use of functional imaging methods to generate maps of regional washout rate estimators is introduced in an animal model. Region-of-interest analysis is introduced using regions specified by the functional maps demonstrates the sensitivity of the methods to the rapid components of cerebral xenon washout. Correspondence among the regional distributions of tissue types as demonstrated by tissue attenuation coefficient, xenon solubility, and washout rate estimators supports the validity of characterizing each pixel by a single exponential response function.