Showing papers on "Perfusion scanning published in 1992"

Magnetic resonance imaging of perfusion using spin inversion of arterial water.

Abstract: A technique has been developed for proton magnetic resonance imaging (MRI) of perfusion, using water as a freely diffusable tracer, and its application to the measurement of cerebral blood flow (CBF) in the rat is demonstrated. The method involves labeling the inflowing water proton spins in the arterial blood by inverting them continuously at the neck region and observing the effects of inversion on the intensity of brain MRI. Solution to the Bloch equations, modified to include the effects of flow, allows regional perfusion rates to be measured from an image with spin inversion, a control image, and a T1 image. Continuous spin inversion labeling the arterial blood water was accomplished, using principles of adiabatic fast passage by applying continuous-wave radiofrequency power in the presence of a magnetic field gradient in the direction of arterial flow. In the detection slice used to measure perfusion, whole brain CBF averaged 1.39 +/- 0.19 ml.g-1.min-1 (mean +/- SEM, n = 5). The technique's sensitivity to changes in CBF was measured by using graded hypercarbia, a condition that is known to increase brain perfusion. CBF vs. pCO2 data yield a best-fit straight line described by CBF (ml.g-1.min-1) = 0.052pCO2 (mm Hg) - 0.173, in excellent agreement with values in the literature. Finally, perfusion images of a freeze-injured rat brain have been obtained, demonstrating the technique's ability to detect regional abnormalities in perfusion.

On the precision of diffusion/perfusion imaging by gradient sensitization.

Abstract: Computer simulation is used to assess the precision and accuracy of diffusion and perfusion parameters derived from a set of gradient-sensitized images. Under ideal experimental conditions, a moderate signal-to-noise level (ca. 40) suffices to estimate diffusion coefficients to within 20% relative precision. However, estimation of a typical cerebral perfusion fraction of 5% to within 20% relative precision requires signal-to-noise levels of ca. 400. Simulations also show that systematic errors in perfusion fraction estimation, as well as understimation of the uncertainties in perfusion parameters (by X-squared analysis), will be found at moderate signal-to-noise levels. © 1992 Academic Press, Inc.

Effect of patient motion on tomographic myocardial perfusion imaging.

Abstract: We evaluated the effect of patient motion on inducing false-positive tomographic 201Tl myocardial perfusion studies. The effects of the angle of camera rotation at which movement occurs, the direction of movement and the distance of movement were studied. Movement was stimulated by shifting the raw data from normal motion-free 201Tl tomographic myocardial perfusion studies. The visual detectability of motion artifact was evaluated with receiver-operating characteristic curve analysis. The clinical importance of patient movement was determined by measuring the incidence of quantitative bull's-eye abnormalities induced by motion. Visual artifacts were more detectable and quantitative abnormalities more frequent as the distance of movement increased. Artifacts from 3.25 mm of movement were not visually detectable. Artifacts from 6.5 mm of movement were visually detectable, but were infrequently clinically important. Movement of 13 mm or greater frequently caused quantitative abnormalities. Quantitative abnormalities from axial movement were more frequent than artifacts from lateral movement. Quantitative abnormalities were more frequent when the movement occurred at the beginning or end. We conclude that when patients move during 201Tl tomographic myocardial perfusion imaging, the incidence and character of false-positive results depend on the angle of camera rotation at which the movement occurs, the direction of the movement and distance of the movement.

A quantitative approach to technetium-99m hexamethylpropylene amine oxime

Abstract: A non-invasive, simple method for the quantitative evaluation of brain perfusion is presented using intravenous radionuclide angiography with technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO). Graphical analysis was employed for the evaluation of the unidirectional influx constant (ku of the tracer from the blood to the brain. The ku values were standardized to provide objective and comparable values, brain perfusion indices (BPI), among studied subjects by setting the ratio of ROIbrain size to ROIaorta size at 10. The wholebrain BPI values for the normal control subjects showed a significant negative correlation with advancing age (r = -0.632, P =0.0204, n =13). The mean of the wholebrain BPI of 7.0 (SD =1.4) in 20 patients with cerebrovascular disorders was significantly lower than that of 10.6 (SD =1.5) in 13 normal control subjects. The BPI measurements showed only minimal intra- and interobserver variability. Changes of the ratio of ROIaorta size and ROIbmin size did not significantly influence the BPI values. Hemispherical BPI values in 19 subjects (n =38) showed highly significant correlations with the hemispherical mean cerebral blood flow values obtained from Xenon-133 single photon emission tomography (SPET) (r =0.926, P =0.0001 for the early picture method and r =0.932, P =0.0001 for the sequential picture method). This technique is easy to apply as an adjunct to SPET and may be helpful in the quantitative evaluation of brain perfusion in routine clinical studies.

Intrasubject comparison between technetium-99m-ECD and technetium-99m-HMPAO in healthy human subjects.

Abstract: The pharmacokinetics and quality of planar and SPECT brain imaging of two 99mTc-labeled brain perfusion agents, d,l-hexamethyl propylene amine oxime (HMPAO) and ethyl cysteinate dimer (ECD), were compared in seven healthy, normal subjects. Both radiopharmaceuticals showed rapid brain uptake and had a net brain washout of less than 5% during the first 20 min after drug administration. However, during the same time period, 99mTc-ECD images of the head showed significantly less background facial uptake and retention when compared to 99mTc-HMPAO images. The brain-to-background contrast ratio of 99mTc-ECD (brain/neck) continued to improve over time and by 5 hr postadministration was 17 to 1 versus 2 to 1 for 99mTc-HMPAO. SPECT brain images of both agents show gray/white matter ratios that were unchanged over time and an intracerebral distribution consistent with blood flow. A blind read of these SPECT images also shows 99mTc-ECD to produce images that were "easier to interpret" with less extracerebral activity as compared to 99mTc-HMPAO. Repeat, whole-body planar spot imaging suggests that 99mTc-ECD was cleared more rapidly from the body than was 99mTc-HMPAO.

Measurement of brain perfusion by volume-localized NMR spectroscopy using inversion of arterial water spins: accounting for transit time and cross-relaxation.

Abstract: The theoretical model for perfusion measurement by NMR using arterial labeling of endogenous water is extended to include the effects of transit time and cross-relaxation of tissue water with macromolecules. Water magnetization in rat brain is monitored using the STEAM method to simultaneously determine the transit time, magnetization transfer rate constant, and perfusion. The results show that the transit time in rat brain is quite short, and thus its effect on perfusion measurement is small. It is also demonstrated both theoretically and experimentally that the steady-state effects of cross-relaxation with macromolecules on perfusion measurement are accounted for by a proper control experiment.

Cerebral blood flow abnormalities in adults with infantile autism

Abstract: Structural brain abnormalities have recently been discovered using magnetic resonance imaging in infantile autism, a neurodevelopmental disorder of unknown etiology However, functional neuroimaging studies in autism using positron emission tomography have had conflicting results and have not explained how the known structural brain abnormalities in autism act in a functioning brain to produce autistic behavior Using a new technology, high-resolution brain single photon emission tomography, we studied and scanned four young adults with infantile autism and four age-matched controls using the labeled ligand 99mTc-D,L-hexamethyl-propylene amine oxime (99mTc-HMPAO) Total brain perfusion was significantly decreased in autism subjects (range, 58% to 72% of controls, p less than or equal to 02) In addition to the globally decreased perfusion, the autism group also had regionally decreased flow in the right lateral temporal and right, left, and midfrontal lobes compared with controls (p less than or equal to 02, Mann-Whitney t-test)

A comparison of brain perfusion SPECT in cocaine abuse and AIDS dementia complex.

Abstract: Intravenous drug use is a major risk factor for HIV-1 infection. Since both AIDS dementia complex (ADC) and cocaine have been associated with abnormal brain perfusion imaging, we compared the scintigraphic patterns of ADC patients and cocaine polydrug users with normal control subjects using 99mTc-HMPAO SPECT. We found a high incidence of cortical defects in both ADC (100%) and cocaine-dependent (90%) subjects. In the cocaine and ADC patients, cortical defects were most frequent in the frontal, temporal and parietal lobes and occurred with similar frequency in the two populations. In both groups, the number of cortical defects per subject was higher than normal subjects (10.0 +/- 5.0 for ADC, 10.1 +/- 5.2 for cocaine and 0.7 +/- 1.5 for normal), background activity was high (a 65% and 60% incidence for ADC and cocaine, respectively), and basal ganglia involvement was frequent (40% and 65% for ADC and cocaine). We conclude that the brain perfusion pattern, while a sensitive indicator of ADC, cannot be distinguished from chronic cocaine polydrug use and caution should therefore be applied before entertaining a specific diagnosis.

Theoretical principles of perfusion imaging. Application to magnetic resonance imaging.

Abstract: Perfusion magnetic resonance imaging (MRI) offers relative safety (no ionizing radiation), high spatial/temporal resolution, multi-orientation imaging capability, and relative low cost when compared with sophisticated techniques, such as positron emission tomography (PET). Several methods have been recently proposed to image perfusion. Some techniques mimic conventional nuclear medicine principles, but use radioactively inert tracers. Other approaches directly use blood as an endogenous natural tracer. Such methods are totally noninvasive, and offer original insights, for instance by monitoring variations in blood oxygenation in human brain cortex during activation tasks. These methods are presented and compared. Emphasis is given on advantages and drawbacks, and potential clinical applications.

Magnetic resonance perfusion/diffusion imaging of the excised dog kidney.

Abstract: Pickens DR, Jolgren DL, Lorenz CH, Creasy JL, Price RR. Magnetic resonance perfusion/diffusion imaging of the excised dog kidney. Invest Radiol 1992;27:287–292. RATIONALE AND OBJECTIVES. The authors developed a model of tissue capillary beds applicable to perfusion/diffusion imaging with magnetic resonance imaging (MRI). The model consists of a formalin-fixed excised dog kidney attached to a variable speed pump. With this system, it is possible to perfuse the kidney at selected rates. METHODS. Using the intravoxel incoherent motion model (IVIM), the apparent diffusion coefficient (ADC), diffusion coefficient (D), and perfusion fraction (f) were computed for a region of interest (ROI) in the renal cortex and in the medulla of seven kidneys, one of which was injected with a vasodilator before fixation. ADC and D values were computed for both cortex and medulla. These values were normalized to zero flow and plotted against renal perfusion. The perfusion fraction f was expressed in percent and was not normalized to zero flow. RESULTS. Normalized ADC and f were correlated with tissue perfusion rates using the Spearman rank-sum test (n = 18, rs> 0.5, P ≥ .02 for the standard preparation in both cortex and medulla), whereas normalized D (rs ≦ 0.5) was uncorrelated for both preparations in cortex and medulla. CONCLUSIONS. The isolated perfused dog kidney is a useful model of tissue capillary beds for perfusion imaging technique development. The perfusion/diffusion-related parameters ADC and f increase as flow increases in the tissues, whereas D does not.

Utility of Various Radionuclide Techniques for Distinguishing Ischemic From Nonischemic Dilated Cardiomyopathy

Abstract: Background.— Clinically, ischemic and nonischemic (idiopathic) dilated cardiomyopathy may be difficult to distinguish. Radionuclide ventriculography and exercise testing with thallium-201 scintigraphy are often used in an attempt to differentiate them noninvasively. With these techniques, the presence of (1) left ventricular (LV) regional asynergy, (2) depressed LV systolic function with normal right ventricular function, and/or (3) thallium-201 perfusion abnormalities traditionally has been regarded as evidence of ischemic heart disease. We assessed the incidence with which these abnormalities occur in patients with nonischemic-dilated cardiomyopathy. Methods. — Seventy-six patients (45 men, 31 women, aged 18 to 75 years) with invasively proven nonischemicdilated cardiomyopathy underwent radionuclide ventriculography (n = 75) and provocative thallium-201 perfusion imaging (n = 17). Results.— Regional LV wall motion abnormalities were noted in 48% of patients, and 54% had LV systolic dysfunction without concomitant right ventricular dysfunction. Reversible and/or fixed exercise-induced thallium-201 perfusion abnormalities occurred in 94% of the patients studied. Conclusions.— Radionuclide ventriculography and exercise testing with thallium perfusion imaging cannot be used reliably to differentiate ischemic from nonischemic dilated cardiomyopathy, since many patients with the latter have radionuclide evidence of LV segmental wall motion abnormalities, selective LV systolic dysfunction, and segmental perfusion abnormalities. (Arch Intern Med. 1992;152:769-772)

Comparison between thallium-201, technetium-99m-sestamibi and technetium-99m-teboroxime planar myocardial perfusion imaging in detection of coronary artery disease.

Abstract: Technetium-99m-sestamibi (MIBI) and 99mTc-teboroxime (TEBO) are two new myocardial perfusion imaging agents. The purpose of this prospective study was to compare MIBI and TEBO to 201TI planar imaging. Eighteen patients with significant coronary artery disease on coronary angiogram were submitted to three treadmill stress tests performed within 3 mo and were imaged with the three radiopharmaceuticals as follows. 1. TI: 2.2 mCi, immediate and delayed views (4 hr later, 8 min/view). 2. TEBO: 15-20 mCi at stress (1 min/view) and a second injection was repeated 4 hr later at rest (20-25 mCi). 3. MIBI: 15-18 mCi at stress (8 min/view) and 1-4 days later, 15-18 mCi at rest. Patients achieved similar levels of exercise. A blinded reading was performed by three observers. The left ventricle was divided into three segments/view and ischemic/normal wall ratios were also determined. Segmental comparison showed an agreement in 85% (138/162) of the segments between TI and TEBO, in 92% (149/162) between TI and MIBI and in 84% (136/162) between MIBI and TEBO. Abnormal TI, MIBI and TEBO studies were seen in 16 (89%), 16 (89%) and 15 (83%) patients, respectively, detecting 77, 75 and 65 abnormal segments. Ischemic-to-normal wall ratios were 0.75 +/- 0.06, 0.73 +/- 0.08 and 0.78 +/- 0.08 for TI, MIBI and TEBO, respectively. In conclusion, although the biologic characteristics of these agents are different, this study showed a good correlation between them in detection of significant coronary artery disease (high pretest likelihood population).

Functional imaging of peripheral vascular disease: a comparison between exercise whole-body thallium perfusion imaging and contrast arteriography.

Abstract: Whole-body thallium scintigraphy was used to study leg muscle perfusion in 12 healthy individuals and 31 patients with peripheral vascular disease. Subjects were scanned immediately after exercise and 4 hr later. Buttock, thigh and calf perfusion were measured in terms of fractional uptake relative to whole-body activity, percent change in fractional uptake over 4 hr and interextremity symmetry ratios. The results were compared to contrast arteriography on a region by region basis. The overall sensitivity and specificity of thallium scintigraphy were 80% and 73%, respectively. The results suggest that thallium scintigraphy may provide useful information about the hemodynamic significance of noncritical anatomic lesions.

Determination of changes in tumor blood perfusion after hydralazine treatment by dynamic paramagnetic-enhanced magnetic resonance imaging.

Abstract: Magnetic resonance imaging, using the paramagnetic chelate gadopentetate dimeglumine as a perfusing agent, was used to investigate the effect of the vasoactive drug hydralazine on tumor blood perfusion. The method requires measurements of the magnetic resonance image intensity changes with time on a pre-selected region of interest in the tumor image, immediately following intravenous injection of gadopentetate dimeglumine. The present study showed that the initial slope of the intensity-time curve can be used, to a first approximation, to infer tumor blood perfusion. With the dynamic imaging technique, it was demonstrated that, in the KHT sarcoma implanted intramuscularly in the hind leg of C3H/HeN mice, intraperitoneal administration of hydralazine reduced the volume-averaged tumor blood perfusion in a dose-dependent manner. The intrinsically high spatial resolution of magnetic resonance imaging allows a detailed study of the heterogeneous nature of tumor blood perfusion. The potential applications of this imaging technique to study the differential effects of hydralazine on perfusion between tumor and normal tissues will be discussed. The clinical utility of the technique should be promising because of its non-invasive nature.

Thallium-201 single-photon emission computed tomography (SPECT) in the assessment of coronary artery disease.

Abstract: Of all currently available techniques, thallium-201 single-photon emission computed tomography (SPECT) is the most time-tested noninvasive method for the detection of coronary artery disease (CAD). Recent pooled data show an overall sensitivity of 90% and a specificity of 70% for thallium-201 SPECT. Of patients with single-vessel coronary disease, 83% are identified by SPECT. Nearly all patients with double- and triple-vessel coronary disease (93% and 95%, respectively) are also identified. Thallium-201 SPECT imaging is also very effective in diagnosing CAD using pharmacologic stress testing. In certain patient populations (e.g., in sedentary patients or those using anti-ischemic medications), pharmacologic stress testing with dipyridamole or adenosine may be a logical alternative to exercise testing. Moreover, many patients have physical disabilities that preclude appropriate exercise testing. Intravenous adenosine is a very potent direct coronary vasodilator, with the advantage of an ultrashort half-life, which eliminates the need to administer an antagonist in the majority of patients. In addition, the dosage of adenosine can be adjusted during the infusion, if necessary. The importance of thallium-201 SPECT during exercise or pharmacologic vasodilation transcends diagnosis, since it also plays an important role in the prognostic evaluation of patients with stable angina or postmyocardial infarction. Risk evaluation can be done with submaximal exercise electrocardiographic testing, but there is evidence that the addition of perfusion scintigraphy enhances the ability to predict future risk. In patients unable to exercise or to receive dipyridamole or adenosine stress, dobutamine has recently emerged as yet another alternative. Although the reported experience is small with dobutamine thallium perfusion imaging, the test appears safe, well-tolerated, and has good sensitivity and specificity for CAD detection.

Measurement of blood flow and perfusion in the cardiovascular system.

Abstract: Complete evaluation of cardiovascular disease by a single imaging technique requires measurement of bulk flow in blood vessels and estimation of relative or ideally absolute perfusion at the tissue level. Magnetic resonance (MR) measurement of blood flow in arteries and veins has been done using the velocity-encoded phase cine gradient echo technique. This technique has been applied with cine MR to measure normal and pathologically high velocities. Measurement of relative perfusion in the myocardium has used the intravenous injection of T1 relaxation enhancing and magnetic susceptibility MR contrast media with rapid image acquisition using echoplanar imaging. MR images (MRIs) acquired during steady-state distribution or during the first passage of these contrast media have depicted ischemic myocardial regions.

The effect of atenolol on dipyridamole 201Tl myocardial perfusion tomography in patients with coronary artery disease.

Abstract: The effect of atenolol on dipyridamole 201Tl myocardial perfusion tomography was evaluated in 12 patients with angiographically proven coronary artery disease. The patients had dipyridamole 201Tl tomography performed after 7 days treatment with 50 mg atenolol and then repeated after a further 7 days treatment with placebo. The images were interpreted qualitatively by two experienced observers and quantitatively using the Bullseye technique. Qualitative analysis of the images revealed that four of the 12 patients had larger defects on their scans whilst receiving atenolol compared to placebo. The remaining eight patients had defects which were the same size on both treatments. The severity of defects assessed qualitatively was not significantly influenced by atenolol therapy (P = 0.13, McNemera's test). The results obtained with the Bullseye method did not demonstrate significant statistical differences for defect size, degree of reversibility or percentage reversibility whilst the patients were receiving atenolol or placebo (Wilcoxon Rank Sum Test). Atenolol increased the size of perfusion defects on dipyridamole 201Tl tomography qualitatively and quantitatively for four patients in this group of 12 with proven coronary artery disease. Although this did not achieve a high level of statistical significance physicians should be aware that atenolol can influence the images obtained at dipyridamole 201Tl tomography.

Ultrafast MR imaging of water mobility: Animal models of altered cerebral perfusion

Abstract: “Single shot” magnetic resonance (MR) diffusion imaging was used to study the details of signal decay curves in experimental perturbations of cerebral perfusion induced by hypercapnia or death. Despite large perfusion increases observed with dynamic susceptibility-contrast MR imaging, no correlation with these changes was seen in either the diffusion coefficient or any other intravoxel incoherent motion (IVIM) model parameters in dog gray matter as arterial carbon dioxide pressure increased. Non-monoexponential signal decay in cat gray matter was seen both before and after death. In addition, cat gray matter demonstrated a steady decrease in the diffusion coefficient after death. These data are strong evidence that the fast component of the non-monoexponential diffusion-related signal decay is not due solely to perfusion. The authors believe that a second compartment of nonex-changing spins, most likely cerebrospinal fluid, accounts for the non-monoexponential decay.

Capillary Perfusion in the Brain

Abstract: The perfusion mode of cerebral capillaries is still a matter of controversy. Whereas the interrelationships between the density of perfused capillaries, local glucose utilization, and local blood flow in the brain are well known (Klein et al. 1986), the question of the normal perfusion pattern of brain capillaries and of recruitment of capillaries under conditions of high blood flow is still open. The present investigation therefore aimed to test the normal perfusion pattern of brain capillaries by fluorescent staining of capillaries and of their contents. Another question posed by this study was whether drastic increases in cerebral blood flow (CBF) induced by CO2 are accompanied by increases in the number of perfused capillaries. Experiments were performed on awake rats to avoid an influence of anesthesia on capillary perfusion. Since the results of such investigations are critically dependent on the method used to mark the perfused capillaries, additional studies were performed to verify the applicability of the fluorescence method used in the present and the previous (Klein et al. 1986) study. In one series of experiments the densities of perfused capillaries were compared with fluoresceinisothiocyanate (FITC) coupled to globulin, as used in the present study, or to dextran, as applied in studies by Weiss and his group (Buchweitz and Weiss 1986; Francois-Dainville et al. 1986; Grover et al. 1986; Weiss et al. 1982), who came to different conclusions about capillary perfusion from their data; another series of experiments investigated the question of whether the anesthesia, which preceded all the experiments (for placing the catheters), could have influenced the results of the capillary density measurements. To this end, FITC-globulin was injected into a tail vein in naive, untreated control rats and the density of perfused capillaries measured. In the last series of experiments, the capillary structures were stained using fluorescent antibodies against the basal membrane constituent fibronectin. The counts obtained were compared with those obtained with intravascular fluorescent markers. The results showed the validity of the method used and a continuous perfusion of all the capillaries during both normocapnia and hypercapnia.

Dual isotope SPECT in the evaluation of recurrent brain tumor.

Abstract: Dual isotope brain SPECT was performed in a patient with recurrent brain tumor (grade II astrocytoma). In this case, a good coregistration of brain perfusion and tumor images was obtained because Tc-99m HMPAO and the Tl-201 chloride imaging were done simultaneously using a Triad SPECT unit. This method might play an important clinical role in the evaluation of patients with recurrent brain tumors.

Clinical and experimental studies on the mechanism of abnormal accumulation in lung scanning with 123I-IMP.

Abstract: To investigate the intrapulmonary kinetics of N-isopropyl-p-I-123-iodoamphetamine (123I-IMP), lung scanning with 123I-IMP was performed in patients with various lung disorders. Compared with the normal lung field, abnormal accumulation of 123I-IMP was detected in all patients in delayed imaging performed 24 h after 123I-IMP injection. These sites were within areas of absent or reduced perfusion observed by pulmonary perfusion scanning using 99Tcm-macroaggregated albumin (99Tcm-MAA). A similar phenomenon was seen in additional experiments in rabbits with regional pulmonary arterial hypoperfusion resulting from a balloon catheter-induced bronchial occlusion. 123I-IMP accumulation in areas where 99Tcm-MAA images are absent or decreased may be explained by the ability of 123I-IMP to penetrate significantly narrowed microvascular beds with reduced perfusion. Our clinical and experimental results indicate that pulmonary arterial perfusion, particularly hypoperfusion, influence the pulmonary kinetics of 123I-IMP. This compound is a potentially useful non-particulate agent for the assessment of pulmonary arterial perfusion.

Prediction of reversible perfusion defects by quantitative analysis of post-exercise electrocardiogram-gated acquisition of technetium-99m 2-methoxyisobutylisonitrile myocardial perfusion scintigraphy

Abstract: The aim of this study was to assess the reliability of the quantitative analysis of regional wall thickening with electrocardiographic-gated technetium-99m 2-methoxyisobutylisonitrile (SESTAMIBI) in predicting the reversibility of stress-induced perfusion defects. The assumption was that a preserved resting wall thickening in a segment with stress-induced perfusion defect would predict normal resting perfusion. Twenty-five patients with suspected coronary artery disease underwent planar stress-rest SESTAMIBI scintigraphy. The wall thickening was quantitatively evaluated as percentage increase in counts from diastole to systole; a ratio defined as the wall thickening index (WTI) between patient and normal profile (mean - 2 SD) below 1 was considered abnormal. Improvement of the perfusion pattern at rest was observed in 76% (54/71) of segments with a stress-induced perfusion defect; 90% of these segments had a (WTI) > 0.8. Five segments (9%) showed fixed perfusion defects despite a WTI value > 0.8. In conclusion, quantitative analysis of regional wall thickening by electrocardiographic-gated SESTAMIBI identifies segments with reversible perfusion defects; this may overcome the need for studies at rest and may direct the detection of hypoperfused but viable myocardium.

Myocardial perfusion: Contrast echocardiography perspectives

Abstract: Contrast echocardiography may become a useful means of quantifying transmural regional myocardial perfusion patterns, experimentally and clinically, in a variety of settings. Contrast echocardiography has already been used in the operating room to study perfusion during coronary artery bypass graft (CABG) surgery. Other recent studies have demonstrated the ability of contrast echocardiography to predict wall motion improvement following acute myocardial infarction and therapeutic intervention. This is significant in the light of the discrepancy that has recently been shown between epicardial coronary vessel diameter and coronary flow. Studies suggest that both tissue and blood flow and volume may be quantitatively evaluated using contrast echocardiography, and these parameters ultimately may be used to assess tissue viability or vascular reserve. Contrast echocardiography techniques have been shown to be safe and reliable, and provide a high degree of spatial and temporal resolution.