Gated blood-pool emission tomography: a new technique for the investigation of cardiac structure and function

ECG-gated single-photon emission-computed tomography of the intracardiac blood pool is a new technique that has not previously been widely applied. It involves the acquisition of ECG-gated images of the intracardiac blood pools labelled with sodium pertechnetate Tc 99m in 32 projections around the left-anterior hemithorax using a rotating gamma camera. From these images, tomographic sections are reconstructed orthogonal to the long axis of the left ventricle. The heart is therefore imaged three dimensionally, and more extensive information is obtained than in planar radionuclide ventriculography where imaging is usually restricted to only a single projection. Both structure and function can be studied, and the left-ventricular volume and ejection fraction, and wall motion are obtained. Of 50 patients studied, 7 cases are illustrated in order to show normal findings, examples of wall motion that were not shown by planar-contrast and radionuclide ventriculography, examples of the localisation of ventricular hypertrophy, and a comparison between blood-pool and 201TI myocardial tomography.     

Evaluation of left ventricular function using gated planar myocardial imaging with Tc-99m-MIBI

A quantitative index of left ventricular wall motion obtained from ECG-gated planar myocardial images has been developed. Five normal controls and 39 patients with heart disease received an injection of Tc-99m-MIBI (550-740 MBq) at rest, and ECG-gated planar scintigraphy (LAO view) was performed 3 h later. Mean End-diastolic (ED) and end-systolic (ES) myocardial activities were measured using circumferential profile analysis and %count increase (CI) was determined according to the following formula; (ES count-ED count)/(ED count) x 100. The global %CI was compared with the EF obtained from contrast ventriculography (LVG; n = 29) and radionuclide ventriculography using Tc-99m-labelled RBC (RNV; n = 24). The regional %CI was compared with left ventricular wall motion assessed by LVG. The global %CI was correlated well with EF by LVG (r = 0.70) and EF by RNV (r = 0.75). The regional %CI significantly decreased in accordance with wall motion on LVG worsened at impaired region. In conclusion, gated perfusion imaging with Tc-99m-MIBI provides useful information on ventricular function in addition to myocardial perfusion.     

Use of ECG-gated single-photon emission tomography to assess the evolution of perfusion after acute myocardial infarction

Serial improvement in myocardial perfusion images from the acute or subacute to the chronic stage of acute myocardial infarction (AMI) has been attributed to improved coronary microcirculation or cell function after acute ischaemia and reperfusion. However, conventionally used non-gated imaging cannot eliminate the effect of improved regional contraction. We studied the possibility that such scintigraphic improvement reflects the functional recovery by using ECG-gated myocardial perfusion imaging with technetium-99m sestamibi. Nineteen AMI patients who received acute reperfusion therapy underwent ECG-gated myocardial single-photon emission tomography (SPET) in the subacute and chronic stages. Serial changes in regional image count distributions were analysed on the non-gated, end-diastolic (ED) and end-systolic (ES) images by using segmental mean percent peak activity (MPA) and ΔMPA (MPA in chronic stage – MPA in subacute stage) on bull’s-eye polar maps. These changes were compared with those in regional wall motion on biplane left ventriculography (LVG) from the acute (just after reperfusion) to the chronic stage. During the follow-up, regional wall motion remained the same in 42 (group A) but improved in 17 (group B) of the 59 ischaemically compromised segments. MPA showed no improvement in group A but significant improvement in group B on the non-gated and ES images (P<0.0001 and P<0.001, respectively). However, MPA on the ED images showed no improvement in either group. In the follow-up study of AMI, the scintigraphic improvement documented on the non-gated myocardial images appears to be mainly related to the recovery of wall thickening and not to a real improvement in myocardial perfusion. Therefore, ECG-gated myocardial imaging, which enables simultaneous assessment of changes in perfusion and contraction, is preferable to conventional non-gated imaging for follow-up of AMI. Received 26 October 1999 and in revised form 20 January 2000     

Usefulness and limitations of ECG-gated myocardial single-photon emission computed tomography with 99mTc-methoxy-isobutyl-isonitrile (MIBI) in patients with prior myocardial infarction]

To evaluate the relationship between regional wall motion and 99mTc-methoxy-isobutyl-isonitrile (MIBI) uptake, ECG-gated single-photon emission computed tomography (SPECT) with 99mTc-MIBI was performed in 20 patients with prior myocardial infarction. The left ventricular images at end-diastole (ED) and end-systole (ES) were divided into 39 segments, respectively. Based on circumferential profile analysis, relative uptake (%EDc, %ESc), percent count increase (% delta C), and normalized percent count increase (% delta Cn) were analyzed in each segment and compared with regional wall motion indices assessed by echocardiography and left ventriculography. ECG-gated SPECT with 99mTc-MIBI provided high contrast tomograms of the left ventricular myocardium. %EDc and %ESc showed good correlations with regional wall motion indices. % delta C and % delta Cn, however, showed lower correlations compared with %EDc and %ESc. In conclusion, high-quality left ventricular images were obtained with 99mTc-MIBI ECG-gated SPECT, but quantitative analysis based on only percent count increase (% delta C) have limitations for evaluation of regional wall motion.     

The prognostic value of ECG-gated SPECT imaging in patients undergoing stress Tc-99m sestamibi myocardial perfusion imaging

BACKGROUND: The ability of stress radionuclide myocardial perfusion imaging to predict adverse cardiac events is well accepted. As left ventricular systolic function has also been shown to be an important prognostic indicator, the objective of this study was to determine whether electrocardiography (ECG)-gated single photon emission computed tomography (SPECT) functional data add additional power. METHODS AND RESULTS: In this study 3207 patients who underwent stress myocardial perfusion imaging with ECG gating, without early (相似文献   

Cinematic three-dimensional surface display of cardiac blood pool tomography

A method of three-dimensional cinematic display (3D cine) of cardiac blood pool tomography is described. ECG-gated transaxial blood pool imaging was obtained from a set of projection images that were collected from 32 images with 10 ECG-gated images per projection during a 180 degrees arc of a rotating gamma camera. A surface contour of the blood pool was determined by a set of isocount lines (40-55% of the maximum pixel counts) of the transaxial images. 3D cine was made by a depth-shading method, in which brightness of a given point on the contour was set proportional to the distance between the viewing plane and the point and to the incident angle formed by the viewing line and the surface of the point. In 15 patients, 3D cine showed hypokinesia, akinesia, dyskinesia, ventricular aneurysm, and opposite motions of the atria and ventricles. Diagnoses of left ventricular motion by 3D cine agreed well with those by echocardiography and contrast left ventriculography.     

Clinical evaluation of Tl-201 ECG-gated myocardial SPECT--comparison with ECG-gated blood pool SPECT

In order to evaluate the clinical usefulness of the Tl-201 ECG-gated myocardial single photon emission computed tomography (SPECT), we compared the wall motion and the grade of the Tl-201 uptake of the ECG-gated myocardial SPECT with the wall motion of the ECG-gated blood pool SPECT. Materials were 87 patients of 50 old myocardial infarctions (OMIs), 19 hypertrophic cardiomyopathies (HCMs), 2 dilated cardiomyopathies (DCMs) and 16 others. After intravenous injection of 111-185 MBq (3-5 mCi) of Tl-201 at rest, the projection data were acquired using a rotating gamma-camera through 180 degrees, from RAO 45 degrees in 24 directions, each of which consisted of 80-100 beats. For the reconstruction of ED, ES and non-gated images, R-R interval was divided into about 20 (18-22) fractions. In 348 regions of interest (anterior, septal, lateral and inferior wall) in 87 cases, wall motion and the Tl-201 uptake were evaluated to three grades (normal, hypokinesis and akinesis; normal, low and defect, respectively), which were compared with the wall motion of the ECG-gated blood pool SPECT. The wall motion and the grade of the Tl-201 uptake of the ECG-gated myocardial SPECT correlated well with the wall motion of the ECG-gated blood pool SPECT (96.6% and 87.9%, respectively). In conclusion, the ECG-gated myocardial SPECT can provide clear perfusion images and is a very useful diagnostic strategy to evaluate the regional wall motion and perfusion simultaneously.     

Use of ECG-gated SPET to assess the evolution of perfusion after acute myocardial infarction

Serial improvement in myocardial perfusion images from the acute or subacute to the chronic stage of acute myocardial infarction (AMI) has been attributed to improved coronary microcirculation or cell function after acute ischaemia and reperfusion. However, conventionally used non-gated imaging cannot eliminate the effect of improved regional contraction. We studied the possibility that such scintigraphic improvement reflects the functional recovery by using ECG-gated myocardial perfusion imaging with technetium-99m sestamibi. Nineteen AMI patients who received acute reperfusion therapy underwent ECG-gated myocardial single-photon emission tomography (SPET) in the subacute and chronic stages. Serial changes in regional image count distributions were analysed on the non-gated, end-diastolic (ED) and end-systolic (ES) images by using segmental mean percent peak activity (MPA) and AMPA (MPA in chronic stage - MPA in subacute stage) on bull's-eye polar maps. These changes were compared with those in regional wall motion on biplane left ventriculography (LVG) from the acute (just after reperfusion) to the chronic stage. During the follow-up, regional wall motion remained the same in 42 (group A) but improved in 17 (group B) of the 59 ischaemically compromised segments. MPA showed no improvement in group A but significant improvement in group B on the non-gated and ES images (P<0.0001 and P<0.001, respectively). However, MPA on the ED images showed no improvement in either group. In the follow-up study of AMI, the scintigraphic improvement documented on the non-gated myocardial images appears to be mainly related to the recovery of wall thickening and not to a real improvement in myocardial perfusion. Therefore, ECG-gated myocardial imaging, which enables simultaneous assessment of changes in perfusion and contraction, is preferable to conventional non-gated imaging for follow-up of AMI.     

Measurement of left ventricular ejection fraction from gated technetium-99m sestamibi myocardial images

Left ventricular ejection fraction (LVEF) and single-photon emission tomographic (SPET) imaging of the myocardium can be performed after a single technetium-99m sestamibi (MIBI) injection. Sixty patients underwent SPET imaging with MIBI. Immediately after SPET acquisition ECG-gated^99mTc-MIBI perfusion images were acquired using 24 planar images per R-R interval. A new method for measurement of LVEF from the ECG-gated 99mTc-MIBI perfusion images was developed. To validate the method, LVEF derived from MIBI perfusion images was compared with that from conventional radionuclide ventriculography in all 60 patients. Forty patients had evidence of myocardial infarction and 20 had normal perfusion on MIBI imaging. There was no statistically significant difference between LVEF computed from^99mTc-MIBI perfusion images and that from radionuclide ventriculography (r=0.7062,P<0.001). There was little difference associated with the technique (intraobserver variabilityr=0.9772,P<0.001). Interobserver variability was also good (r-0.8233,P<0.001). LVEF from^99mTc-MIBI perfusion images can be obtained at the same time as assessment of myocardial perfusion and in the same orientation and metabolism of the myocardium, thereby permitting more accurate and realistic prognosis and diagnosis in patients with coronary artery disease.     

Combined assessment of regional perfusion and wall motion in patients with coronary artery disease with technetium 99m tetrofosmin

Background

Technetium 99m tetrofosmin is a new^99mTc-labeled myocardial perfusion agent that can be labeled easily and provides excellent myocardial perfusion images. In addition, bolus administration of the tracer allows first-pass radionuclide ventriculography.

Methods and Results

This study examined the diagnostic value of combined assessment of regional perfusion by tetrofosmin tomography and wall motion by first-pass radionuclide ventriculography both at rest and during stress in 24 patients suspected of having coronary artery disease. All patients underwent stress-rest tetrofosmin tomography, stress-delayed thallium 201 tomography, and coronary angiography. Stress tetrofosmin tomography showed abnormal perfusion in all 23 patients with angiographic evidence of coronary artery disease, whereas stress²⁰¹Tl tomography showed abnormal perfusion in 22 of the 23 patients. For detection of significant (≥50% diameter stenosis) stenotic coronary arteries, the two perfusion studies showed similar sensitivities (62% with²⁰¹Tl and 69% with tetrofosmin) and specificities (88% and 100%, respectively). When analysis of regional wall motion was combined with perfusion study, a slightly higher sensitivity was obtained (77%), with similar specificity. The regional wall motion score was concordant with the regional perfusion score in only 42% of the segments at rest and 50% during exercise.

Conclusions

These results suggest that stress tetrofosmin perfusion tomography and stress²⁰¹Tl tomography provided similar diagnostic accuracy for detection of coronary artery disease. The combined assessment of perfusion and function that is feasible with tetrofosmin may enhance diagnostic accuracy in patients with coronary artery disease.     

Evaluation of global and regional left ventricular function using technetium-99m sestamibi ECG-gated single-photon emission tomography

We evaluated a method for the assessment of left ventricular (LV) function with technetium-99m sestamibi ECG-gated single-photon emission tomography (GSPET). GSPET was performed at rest in 21 patients. Images were reconstructed to obtain end-diastolic (ED) and end-systolic (ES) images. Endocardial and epicardial edges of the left ventricle for the ED and ES images were defined using the gradient images and the algorithm developed. LV wall thickness was measured for the mid-ventricular slices of ED and ES images at 10° intervals. The systolic thickening (ST) and the LV ejection fraction [LVEF(GSPECT)] could be determined. These values were compared with the LV ejection fraction (LVEF) estimated using the gated blood pool method. There was a linear correlation between LVEF and ST (r=0.79), and LVEF and LVEF(GSPET) (r=0.87). Histograms of LV thicknesses were generated. Agreement for evaluation of regional wall motion between the method using histograms of LV thicknesses and the gated blood pool study was 92.8% (kappa=0.75). It is concluded that with an appropriate method for LV edge detection, GSPET with ^99mTc-labelled perfusion agents is of use for simultaneous evaluation of myocardial perfusion and assessment of LV function. Received 1 December 1997 and in revised form 26 January 1998     

Gated first pass radionuclide ventriculography. Methods, validation, and applications

Electrocardiographic gating provides an alternative method of acquiring first pass radionuclide ventriculograms from both ventricles. This report details the methods of acquisition and analysis, provides validation and reproducibility data, and describes applications of gated first pass radionuclide ventriculography using a count-based method. Left ventricular ejection fractions measured by gated first pass were correlated quite closely with gated blood pool ventriculography (n = 43; r = 0.95) but less well with contrast angiography (n = 23; r = 0.72). The right ventricular ejection fractions measured by gated first pass compared favorably with gated blood pool ventriculography (n = 32; r = 0.93). When one observer processed the images two times, the reproducibilities of RVEF (n = 10; r = 0.99) and LVEF (n = 10; r = 0.88) were excellent. Similarly, when two observers processed the images independently, the reproducibilities of RVEF (n = 11; r = 0.99) and LVEF (n = 11; r = 0.98) were excellent. The first pass studies were obtained in a right anterior obliquity, which provided the best atrioventricular chamber separation and provided a different view of global ventricular function and segmental wall motion from that provided by the standard blood pool views.     

The scintigraphic evaluation of myocardial infarction and regional ventricular performance using technetium-99m hexakis (t-butylisonitrile) technetium (I) (TBI): A new myocardial imaging agent

Technetium-99m hexakis (t-butylisonitrile) technetium (I) (^99mTc-TBI) is a new myocardial perfusion imaging agent. To determine its potential in the evaluation of myocardial infarction, 15 patients with suspected or confirmed acute infarction were studied by bedside imaging in the coronary care unit. Good-quality planar scintigrams in multiple projections were obtained in 13 patients. Gated perfusion studies were performed in 14 patients, and for comparison 13 of these were restudied 24–72 h later by standard gated equilibrium blood pool radionuclide ventriculography. Conventional and planar scintigraphic criteria for myocardial infarction (acute or old) agreed in 12 (92%) patients (k=0.81, p<0.05). All the infarctions detected by scintigraphy were associated with electrocardiographic Q-waves. Localization of infarction by the electrocardiogram and scintigraphy exhibited moderate agreement (k=0.49, p<0.1). Regional wall motion analysis by standard radionuclide ventriculography and gated ^99mTc-TBI scintigraphy were in complete agreement for 25 (64%) of 39 left ventricular segments (k=0.35, p<0.05). However, in 7 other segments, associated with areas of infarction, regional wall motion abnormalities were noted only on gated ^99mTc-TBI scintigraphy. Therefore, ^99mTc-TBI scintigraphy can readily provide data on regional myocardial perfusion and wall motion, permitting detection and localization of areas of myocardial infarction. The superior imaging properties, ready availability and low cost of ^99mTc point to the considerable potential value of ^99mTc-TBI in assessing patients with suspected or confirmed myocardial infarction.This work was done during the tenure of a British-American Research Fellowship of the American Heart Association and the British Heart Foundation, with Dr. S. Campbell the recipient     

The role of nitrogen 13 ammonia positron emission tomography in predicting functional outcome after coronary revascularization

Background

We sought to evaluate the predictive value of positron emission tomography (PET) by using blood flow imaging with semiquantitative data analysis techniques for predicting recovery of regional function after revascularization. Positron emission tomography in combination with fluorodeoxyglucose (FDG) has been shown to predict tissue recovery after revascularization. Previous studies have suggested a quantitative threshold for perfusion as evaluated by PET that separates scar from viable tissue.

Methods and Results

In a group of 25 patients with impaired regional wall motion at baseline as measured by radionuclide ventriculography, we examined the relationship between myocardial blood flow and functional outcome of myocardial segments in patients who underwent coronary revascularization within 2 months after PET. Regional wall motion was graded on a 5-point scale, from normal to dyskinetic. Regional nitrogen 13 (N-13) ammonia uptake values were expressed as a percentage of maximal myocardial N-13 ammonia uptake and compared with values obtained from healthy volunteers. Results were displayed as polar maps, on which regions of interest were placed corresponding to revascularized vascular territories. We were able to show a statistically significant relationship between regional wall motion abnormalities and decreasing blood flow by N-13 ammonia uptake. An N-13 ammonia uptake of greater than 80% for any given segment was highly accurate in predicting normal or nearly normal postoperative regional wall motion, whereas severely decreased ammonia uptake less than 40% showed normalization of regional wall motion in only 13% of segments.

Conclusions

Relative ammonia uptake of greater than 80% and less than 40% preoperatively had excellent predictive value for functional outcome, but intermediate quantitative ammonia uptake (between 40% to 80%) necessitates additional information to accurately predict functional recovery     

Evaluation of left ventricular wall motion and function in patients with previous myocardial infarction by three-dimensional99mTc-HSAD multigated cardiac pool imaging

To evaluate left ventricular (LV) wall motion stereoscopically from all directions and to calculate the LV volume by three-dimensional (3D) imaging,^99mTc-DTPA human serum albumin-multigated cardiac pool-single photon emission computed tomography (^99mTc-MUGA-SPECT) was performed. A new data processing program was developed with the Application Visualization System-Medical Viewer (AVS-MV) based on images obtained from^99mTc-MUGA-SPECT. In patients with previous myocardial infarction, LV function and LV wall motion were evaluated by 3D-^99mTc-MUGA imaging. The LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were obtained from 3D-^99mTc-MUGA images by the surface rendering method, and the left ventricular ejection fraction (LVEF) was calculated at thresholds of 35% (T1), 40% (T2), 45% (T3), and 50% (T4). There was a strong correlation between the LV volume calculated by 3D-^99mTc-MUGA imaging at a threshold of 40% and that determined by contrast left ventriculography (LVEDV: 194.7 ± 36.0ml vs. 198.7 ± 39.1ml, r = 0.791, p < 0.001; LVESV: 91.6 ± 44.5ml vs. 93.3 ± 41.3ml, r = 0.953, p < 0.001), respectively. When compared with the LVEF data obtained by left ventriculography, significant correlations were found for 3D images reconstructed at each threshold (T1: r = 0.966; T2: r = 0.962; T3: r = 0.958; and T4: r = 0.955). In addition, when LV wall motion obtained by 3D-^99mTc-MUGA imaging (LAT and LAO views) was compared with the results obtained by left ventriculography (RAO and LAO views), there was good agreement. 3D-^99mTc-MUGA imaging was superior in allowing evaluation of LV wall motion in all directions and in assessment of LV function, since data acquisition and image reconstruction could be done within a short time with the three-detector imaging system and AVS-MV. This method appears to be very useful for the observation of both LV wall motion and LV function in patients with ischemic heart disease, because it is a noninvasive examination.     

Improved detection of healed myocardial infarction by Fourier amplitude and phase imaging in two projections: validation with MRI

Biplane Fourier amplitude and phase images from radionuclide ventriculograms were analyzed for the presence of regional wall motion abnormalities in 25 patients who had a total of 33 healed myocardial infarctions (nonviable scar tissue) documented by contrast ventriculography and ECG. This indirect evidence was validated by MRI, which permits direct visualization of healed myocardial infarction. The use of amplitude and phase images in both projections resulted in the detection of more healed myocardial infarctions (91%) than did the use of conventional radionuclide ventriculography with left anterior oblique images alone (67%), because inferior wall infarcts are more readily visualized in the left posterior oblique projection.     

Detection of residual wall motion after myocardial infarction by gated technetium-99m tetrofosmin SPET: a comparison with contrast ventriculography

The differentiation of residual viability from necrotic myocardium in patients with a prior myocardial infarction is important when deciding whether revascularization is indicated. Myocardial viability can be assessed by studying perfusion and regional wall motion. Gated single-photon emission tomography (SPET) imaging allows the simultaneous assessment of perfusion and function through a single study. The aim of this study was to analyse the concordance between wall motion score derived by gated SPET and by contrast ventriculography. Furthermore, the agreement between myocardial perfusion and regional myocardial wall motion was analysed for both techniques. We studied a homogeneous group of 26 consecutive patients with a prior myocardial infarction, using both gated technetium-99m tetrofosmin SPET and contrast ventriculography. A seven-segment model of the left ventricle was employed to score regional myocardial wall motion on images obtained with gated SPET and contrast ventriculography using a four-point scale. Contrast ventriculography was performed within 2 weeks of the gated SPET study. Prevalence of abnormal wall motion (akinetic or dyskinetic) was 24/182 (13%) for gated SPET and 25/182 (14%) for contrast ventriculography (P=NS). There was a high agreement (80%) in wall motion score between gated SPET and contrast ventriculography (3=0.67, P<0.001). The agreement was better in segments with normal or mild to moderate hypoperfusion (82%, 3=0.69) than in those with severe hypoperfusion (67%, 3=0.56). The agreement between myocardial perfusion and myocardial wall motion was 89% (162/182), 3=0.57, for gated SPET and 80% (145/182), 3=0.21, for contrast ventriculography. The relation between the summed wall motion scores per patient on gated SPET and contrast ventriculography was excellent (y=0.81x+2.9, r=0.82, P<0.01). Thirteen (43%) out of 30 segments with severely diminished or no myocardial perfusion showed normal or hypokinetic wall motion on gated SPET, suggesting residual myocardial viability in malperfused regions. Our results suggest that gated SPET imaging is a reliable tool for the assessment of regional wall motion in post-myocardial infarction patients. Furthermore, in patients with a previous myocardial infarction, gated SPET imaging has the potential to detect preserved wall motion in regions with fixed perfusion defects, which might be indicative of residual myocardial viability.     

Value of combined assessment of global and segmental ventricular contraction with right anterior oblique ECG-gated first-pass and left anterior oblique equilibrium radionuclide ventriculography

A semi-automated, variable-region-of-interest method of analysis was used to measure both global and segmental left ventricular (LV) and global right ventricular (RV) contraction with ECG-gated first-pass and equilibrium radionuclide ventriculography. Normal values were defined in 20 healthy volunteers, and in 24 symptomatic patients, the results were compared with right anterior oblique (RAO) contrast left ventriculography. The global LV ejection fraction (LVEF) obtained by equilibrium imaging in the left anterior oblique (LAO) projection correlated closely with the results obtained by the gated first-pass method in the RAO projection (r=0.95) and those obtained with contrast left ventriculography (r=0.94); furthermore, the interobserver variability was small (r=0.985). The normal values for LVEF obtained using radionuclide techniques and contrast ventriculography did not differ, but with the equilibrium radionuclide method, the RV ejection fraction (RVEF) values were underestimated in comparison to those obtained by the RAO gated first-pass technique. In five patients with localised inferior segmental akinesis at contrast angiography, the RAO first-pass cine display demonstrated a corresponding wall-motion abnormality in all cases, but LAO equilibrium cine displays did so in only one out of five patients. For segmental quantitation of LV contraction, a computer programme defined the ventricular edge, divided the RAO LV images into five segments and determined both the segmental area contraction (SAC) and the counts-based segmental ejection fraction (SEF). Radionuclide SAC measurements correlated very strongly with SEF measurements (r=0.94–0.99). Both radionuclide SAC and radionuclide SEF correlated well with contrast angiographic SAC, except in the inferobasal segment. Mean radionuclide SAC (29%) for the five segments did not differ from mean contrast SAC (29%). This combined protocol enables rapid and accurate biventricular assessment of global and segmental contraction. Significant diagnostic value exists in combining these two acquisition protocols in specific clinical situations.     

Dobutamine-stress electrocardiographically gated positron emission tomography for detection of viable but dysfunctional myocardium

PURPOSE: This study was performed to determine whether low-dose dobutamine stress electrocardiography (ECG)-gated fluorine-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) can assess wall motion and identify myocardium without contractile reserve despite preserved FDG uptake. METHODS: Fifty-three patients with myocardial infarction and normal sinus rhythm underwent ECG-gated FDG-PET and transthoracic echocardiography. Wall motion of 10 segments of the left ventricle was graded as normal, hypokinetic, or akinetic/dyskinetic. RESULTS: In 365 (76%) of 480 segments, assessment of wall motion was concordant between the 2 modalities. In 30 patients dobutamine-stress ECG-gated FDG-PET was performed. In 13 (50%) of 26 dysfunctional segments with normal FDG uptake, 16 (36%) of 44 dysfunctional segments with mildly reduced FDG uptake and 12 (25%) of 48 dysfunctional segments with moderately reduced FDG uptake, wall motion was improved by dobutamine infusion. CONCLUSION: Assessment of left ventricular wall motion with ECG-gated FDG-PET is feasible, and dobutamine stress ECG-gated FDG-PET can simultaneously identify metabolic viability and contractile reserve.