Quantification of myocardial infarct size by technetium-99m pyrophosphate single photon emission computed tomography

Myocardial infarct size in 41 patients with the first attack of acute transmural myocardial infarction (MI) was assessed by technetium-99m pyrophosphate single photon emission computed tomography (99mTcPYP-SPECT). A ratio of the number of voxels of 99mTcPYP uptake into the infarct area to that into the thorax was calculated as a parameter of MI size. The ratio was positively correlated with both peak CPK activity (r = 0.53, p less than 0.005, n = 24) and extent score in 201TI-SPECT (r = 0.70, p less than 0.005, n = 14) significantly in patients with anterior MI but not in patients with inferior MI. There was also significant negative correlation between the ratio and the left ventricular ejection fraction (LVEF) measured by RI angiography in both acute (r = -0.67, p less than 0.005, n = 18) and chronic (r = -0.75, p less than 0.005, n = 25) phases in patients with anterior MI. Recovery in LVEF at chronic phase was noted in patients with small anterior MI but not with large anterior MI. 8 of 14 patients with inferior MI had right ventricular MI, that might have affected evaluation of MI size and resulted in no correlation between variables. It was suggested that 99mTcPYP-SPECT was a useful method to evaluate MI size and to predict prognosis of cardiac function in patients with anterior MI but not in patients with inferior MI.     

Simultaneous assessment of wall motion and myocardial perfusion by technetium-99m methoxy isobutyl isonitrile

The aim of this study was to assess whether or not myocardial uptake of Technetium-99m methoxy isobutyl isonitrile (Tc-MIBI) indicated myocardial viability. We performed simultaneous Tc-MIBI angiography and myocardial SPECT at rest on 12 patients with suspected coronary artery disease. Left ventricle was divided into 3 segments, and regional wall motion was graded as normal, hypokinesis and akinesis/dyskinesis. Myocardial uptake of Tc-MIBI was assessed as normal, reduced and absent in each segment. In segments with normal and reduced Tc-MIBI uptake, 7% (2 of 28) and 33% (2 of 6) showed wall motion abnormalities of akinesis/dyskinesis, respectively. However, all segments with absent Tc-MIBI uptake had asynergy of akinesis/dyskinesis (2 of 2, 100%). Myocardial Tc-MIBI uptake at rest indicated wall motion abnormalities and was considered to be useful for the evaluation of myocardial viability. First-pass radionuclide angiography followed by myocardial SPECT with Tc-MIBI demonstrated to be useful for the simultaneous assessment of the left ventricular wall motion and myocardial perfusion.     

Evaluation of myocardial viability with technetium-99m hexakis-2-methoxyisobutyl isonitrile and iodine-123 phenylpentadecanoic acid and single photon emission tomography

The detection of viable myocardium in infarcted regions, i.e. hibernating myocardium, is a major goal in clinical cardiology today. We applied combined planar and single photon emission tomography (SPET) to the non-invasive estimation of the left ventricular ejection fraction (LVEF), myocardial blood flow and free fatty acid uptake in the heart. Of the 31 patients with coronary artery disease, 25 (81%) had had a previous myocardial infarction. All patients had at least one persistent perfusion defect on the stress-rest technetium-99m hexakis-2-methoxyisobutyl isonitrile (Sestamibi) study, and the results revealed 57/124 (46%) persistent perfusion defects. As a part of the perfusion study, the LVEF was measured at rest using the first-pass ^99mTc-Sestamibi injection, and the mean LVEF was 47% ±9% (mean ± 1 standard deviation). Iodine-123 phenylpentadecanoic acid (¹²³I-pPPA) imaging at rest was performed within 2 weeks from the perfusion study. Then 6-mm transaxial, sagittal and coronal slices of the perfusion and ¹²³I-pPPA studies were reconstructed. The bull's eye displays of the coronal slices were visually surveyed and divided into 4 quadrants: anterior, lateral, posterior and septal. The following image score was used: 0 = fixed defect, 1 = partial uptake and 2 =normal uptake. Moreover an index of metabolic reserve (MR) was calculated by dividing the bull's eye of the ¹²³I-pPPA study by the bull's eye of resting ^99mTc-Sestamibi, and its maximum value was normalized to 100%. Fourteen segments (25%) had a normal ¹²³I-pPPA uptake with a MR value of 96% ±8%. Twenty-two segments (39%) had a partial ¹²³I-pPPA uptake with a MR of 74% ±20%, whereas 21 segments (36%) had no ¹²³I-pPPA uptake and a very low MR of 36%±34%. There was a highly significant correlation (r =0.70) between LVEF and MR. These findings suggest that it is possible to identify viable myocardium by measuring contractile function (first-pass, multiple-gated ^99mTc-Sestamibi) and myocardial perfusion (stress-rest ^99mTc-Sestamibi) and by combining these parameters with myocardial fatty acid uptake (1231-pPPA) studies. Correspondence to: IT Kuikka     

Property of electrocardiogram gated single photon emission tomography by 99mTc-methoxy isobutyl isonitrile]

99mTc-methoxy isobutyl isonitrile (MIBI) is a new developed myocardial perfusion imaging agent. Because this compound has higher photon energy than thallium (Tl), electrocardiogram gated single photon emission tomography (SPECT): end-diastolic (ED) and end-systolic (ES) short axis (SA) images could be taken. To investigate property of gated MIBI SPECT, MIBI myocardial scintigraphy, Tl scintigraphy (TMS) and analysis of left ventricular wall motion were performed in 6 patients with myocardial infarction. Left ventricle was divided into 8 segments. Perfusion defect (PD) was scored: "0" (normal), "1" (hypo-perfusion), "2" (defect). Wall motion abnormality (WMA) was also scored: "0" (normokinesis), "1" (hypo-kinesis), "2" (a-, dys-kinesis). Severity and extent of PD and WMA were calculated. Severity of WMA was 3.0 +/- 2.0 (M +/- SD), severity of PD was 3.3 +/- 1.7 in TMS, 3.7 +/- 1.3 in no-gated MIBI, 5.0 +/- 0.6 in ES-MIBI, 7.3 +/- 2.0 in ED-MIBI. Extent of WMA was 2.3 +/- 1.0. Extent of PD was 2.5 +/- 1.3 in TMS, 3.0 +/- 1.6 in no-gated MIBI, 3.5 +/- 0.8 in ES-MIBI, 4.8 +/- 1.0 in ED-MIBI. Compared with wall motion abnormality, severity and extent of PD in ED-MIBI was larger. From our data, it is concluded that perfusion defect in ED-MIBI was overestimated significantly. When we evaluate gated MIBI image, we must consider this property.     

Prescintigraphic morphine application for abdominal adenocarcinoma imaging, with technetium-99m methoxy isobutyl isonitrile

Imaging of tumors with cationic tracers, especially with technetium-99 methoxy isobutyl isonitrile ((99m)Tc-MIBI), revealed high specificity for the diagnosis and follow up of various malignancies. However, these radiopharmaceuticals are of limited value for the diagnosis of malignancies of the abdominal region due to the immediate biliary secretion of the tracer and the associated high background activity. In a prospective, single-blinded protocol, patients with endoscopically diagnosed gastrointestinal malignancies were assigned to undergo (99m)Tc-MIBI imaging of the abdomen. To overcome biliary secretion of cationic tracer we administered 0.04 mg/kg morphine hydrochloride intravenously before the administration of 600 MBq (99m)Tc-MIBI. Planar images were performed in the anterior and posterior views with a double-headed gamma camera and with 3 min acquisition time, followed by single photon emission tomography images (3 degrees, 20 sec/frame). Results were compared to findings of endoscopy, computed tomography scan and surgery. Twenty four patients 17 male and 7 female , mean age 69 years, range 52-83, years were enrolled. All patients suffered from adenocarcinoma, (19 from colorectum, 3 from gastric, 1 from pancreatic and one patient had both gastric and colorectal adenocarcinoma, for a total of 25 tumor lesions). The primary objective- inhibition of biliary secretion- was achieved in 23 of the 24 patients. (99m)Tc-MIBI-imaging was accumulated intra-abdominally in 19 patients. In 2 patients the tumor was endoscopically completely removed before the scan. In these two patients (99m)Tc-MIBI imaging showed no intra-abdominal tracer accumulation. When compared to the endoscopic findings, (99m)Tc-MIBI imaging showed time positive results in 13 of the 23 remaining individual tumor lesions, false positive in 6 and false negative in 4. This study showed a sensitivity of 57% and a specificity of 20% of the above technique for the identification of intra-abnominal adenocarcinomas. Correct diagnosis did not correlate with tumor size. In conclusion, prescintigraphic morphine administration inhibits background activity coming from biliary secretion, and enables better intra-abdominal (99m)Tc-MIBI imaging but with limited sensitivity and poor specificity.     

Evaluation of myocardial viability with technetium-99m hexakis-2-methoxyisobutyl isonitrile and iodine-123 phenylpentadecanoic acid and single photon emission tomography.

The detection of viable myocardium in infarcted regions, i.e. hibernating myocardium, is a major goal in clinical cardiology today. We applied combined planar and single photon emission tomography (SPET) to the non-invasive estimation of the left ventricular ejection fraction (LVEF), myocardial blood flow and free fatty acid uptake in the heart. Of the 31 patients with coronary artery disease, 25 (81%) had had a previous myocardial infarction. All patients had at least one persistent perfusion defect on the stress-rest technetium-99m hexakis-2-methoxyisobutyl isonitrile (Sestamibi) study, and the results revealed 57/124 (46%) persistent perfusion defects. As a part of the perfusion study, the LVEF was measured at rest using the first-pass 99mTc-Sestamibi injection, and the mean LVEF was 47% +/- 9% (mean +/- 1 standard deviation). Iodine-123 phenylpentadecanoic acid (123I-pPPA) imaging at rest was performed within 2 weeks from the perfusion study. Then 6-mm transaxial, sagittal and coronal slices of the perfusion and 123I-pPPA studies were reconstructed. The bull's eye displays of the coronal slices were visually surveyed and divided into 4 quadrants: anterior, lateral, posterior and septal. The following image score was used: 0 = fixed defect, 1 = partial uptake and 2 = normal uptake. Moreover an index of metabolic reserve (MR) was calculated by dividing the bull's eye of the 123I-pPPA study by the bull's eye of resting 99mTc-Sestamibi, and its maximum value was normalized to 100%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adenosine coronary vasodilation quantitative technetium 99m methoxy isobutyl isonitrile myocardial tomography in the identification and localization of coronary artery disease

Background

Exercise and dipyridamole ^99mTc-labeled methoxy isobutyl isonitrile (MIBI) myocardial scintigraphy have been widely used for the diagnosis of coronary artery disease (CAD). However, only limited data on adenosine ^99mTc-labeled MIBI cardiac imaging are currently available. This study was designed to assess the accuracy of quantitative adenosinerest ^99mTc-labeled MIBI tomography in the diagnosis and localization of CAD.

Methods and Results

Fifty-seven consecutive patients with suspected CAD who underwent coronary angiography and 22 normal volunteers were studied. All patients underwent ^99mTc-labeled MIBI tomography after administration of adenosine (140 μg/kg intravenously for 6 minutes) and at rest. A total of 171 vascular coronary territories were analyzed quantitatively. All patients with CAD (≥50% luminal stenosis) (n=55) had abnormal ^99mTc-labeled MIBI tomograms. The normalcy rate was 86% by quantitative analysis. Overall sensitivity, specificity, and diagnostic accuracy for detection of individual stenosed vessels were 84%, 87%, and 85%, respectively. In patients with one-vessel CAD (n=24), sensitivity and diagnostic accuracy in the detection of individual stenosed vessels were significantly (p<0.05) higher compared with patients with multivessel CAD (n=31). Moreover, 75% of patients with one-vessel disease showed a scintigraphic pattern characterized by the presence of perfusion defects in only one coronary artery territory, and 74% of patients with multivessel disease showed a scintigraphic pattern characterized by the presence of perfusion defects in two or more coronary artery territories. Sensitivity, specificity, and diagnostic accuracy for detecting individual diseased vessels were similar in patients without previous myocardial infarction (n=18) compared with those with previous myocardial infarction (n=39). In myocardial territories related to noninfarcted areas (n=124), sensitivity and specificity in the detection of stenosed vessels were 75% and 88%. In infarcted areas (n=47), sensitivity and specificity in the detection of stenosed vessels were 98% and 80% (differences not significant vs noninfarcted areas).

Conclusions

Adenosine-controlled coronary vasodilation combined with quantitative ^99mTc-labeled MIBI tomography is accurate for identifying patients with CAD and localizing individual stenosed coronary arteries.     

Comparison of thallium-201 and technetium-99m teboroxime myocardial single photon emission tomography with coronary arteriography

Myocardial single photon emission tomography (SPET) using technetium-99m teboroxime (teboroxime) was studied and the results compared with those of thallium-201(thallium) SPET and coronary arteriography in 19 patients. Resting teboroxime SPET was performed initially. Two hours later, exercise teboroxime SPET was performed. Exercise ergometer tests for both teboroxime and thallium were carried out in a supine position. The levels of exercise achieved for both tests were similar. Agreement for the identification of myocardial segments between thallium SPET and teboroxime SPET was 147/171(86%) (NS). When a significant stenosis was defined as 75% or 50%, agreement between two radiopharmaceuticals for the detection of diseased vessels was 89% (NS, = 0.601) or 88% (NS, = 0.713), respectively. In only 2/19 cases were inferior and posterior segments (3/171) difficult to interpret in teboroxime SPET due to hepatic activity. Thus, teboroxime SPET with a short data acquisition time resulted in a rapid completion for each study and had a good correlation with thallium SPET. Offprint requests to: M. Oshima, M.D., Ph.D. Department of Radiology Nagoya First Red Cross Hospital     

Comparison of thallium-201 and technetium-99m teboroxime myocardial single photon emission tomography with coronary arteriography.

Myocardial single photon emission tomography (SPET) using technetium-99m teboroxime (teboroxime) was studied and the results compared with those of thallium-201(thallium) SPET and coronary arteriography in 19 patients. Resting teboroxime SPET was performed initially. Two hours later, exercise teboroxime SPET was performed. Exercise ergometer tests for both teboroxime and thallium were carried out in a supine position. The levels of exercise achieved for both tests were similar. Agreement for the identification of myocardial segments between thallium SPET and teboroxime SPET was 147/171(86%) (NS). When a significant stenosis was defined as greater than or equal to 75% or greater than or equal to 50%, agreement between two radiopharmaceuticals for the detection of diseased vessels was 89% (NS, k = 0.601) or 88% (NS, k = 0.713), respectively. In only 2/19 cases were inferior and posterior segments (3/171) difficult to interpret in teboroxime SPET due to hepatic activity. Thus, teboroxime SPET with a short data acquisition time resulted in a rapid completion for each study and had a good correlation with thallium SPET.     

Unusual extracardiac findings detected on myocardial perfusion single photon emission computed tomography studies with Tc-99m sestamibi

The authors describe the incidence and various uptake patterns of Tc-99m sestamibi (MIBI) in the extracardiac area due to unusual causes on myocardial perfusion single photon emission computed tomography (SPECT) studies. Seven patients are presented in whom incidental extracardiac findings were observed during the interpretation of the raw data besides the routine evaluation of myocardial reconstructed SPECT slices. These 7 patients were detected out of 582 consecutive patients (1.2%) who had myocardial perfusion SPECT with Tc-99m MIBI. The findings on the raw data led to additional reconstruction of thoracic SPECT images and eventually detailed examination of the extracardiac area. Two of the patients underwent surgery because of incidental extracardiac findings (thymoma and multinodular goiter) on cardiac scintigraphy. Other causes of increased extracardiac activity were the intestine protruded through the left hemithorax, uptake in the pulmonary arterial wall, and pulmonary interstitial fibrosis due to sarcoidosis. The reasons for decreased Tc-99m MIBI accumulation in the extracardiac area in the 2 other patients were significantly dilated pulmonary arteries and hydatic cyst, which were not defined before to our knowledge. Familiarity with the normal biodistribution and variable uptake patterns in the raw images becomes necessary during the interpretation of myocardial SPECT in order not to miss very unusual incidental extracardiac uptake or information that could lead to alteration in patient management. Potential underlying mechanisms of extracardiac Tc-99m MIBI accumulation are discussed, and the literature about noncardiac Tc-99m MIBI findings detected on myocardial perfusion SPECT studies was reviewed.     

Long-term prognostic value of exercise technetium-99m tetrofosmin myocardial perfusion single-photon emission computed tomography

Background

Exercise ^99mTc-tetrofosmin single-photon emission computed tomography (SPECT) is a useful tool for short- and medium-term risk stratifications. Currently, the long-term prognostic application of this technique has not been evaluated.

Methods and Results

Exercise ^99mTc-tetrofosmin was performed in 655 consecutive patients. Ten patients who underwent revascularization <60?days after nuclear testing were excluded from the analysis. The present data are based on 638 patients with complete follow-up. An abnormal SPECT study was defined as the presence of fixed and/or reversible perfusion defects. End points were cardiac death, nonfatal infarction, and late coronary revascularization. A total of 344 (54%) patients had an abnormal SPECT study. Perfusion defects included fixed defects alone in 186 patients (29%) and reversible defects in 158 (25%) patients. During a mean follow-up of 11.0?±?3.3?years, 174 (27%) patients died (all-cause mortality). Nonfatal myocardial infarction occurred in 76 (12%) patients, and late coronary revascularization was performed in 194 (30%) patients. Univariable and multivariable Cox proportional hazard regression analyses showed that exercise ^99mTc-tetrofosmin SPECT provided prognostic information incremental to clinical data and exercise test data. Patients with a normal SPECT had a relatively favorable long-term prognosis, in contrast to patients with an abnormal study who had a significantly increased risk of cardiac events. The SPECT parameters abnormal scan, reversible defect, and summed rest score were strong predictors of long-term outcome.

Conclusion

Exercise ^99mTc-tetrofosmin myocardial perfusion SPECT has an incremental long-term prognostic value over clinical and stress test parameters for the prediction of major adverse cardiac events.     

Motor stimulation response by technetium-99m hexamethylpropylene amine oxime split-dose method and single photon emission tomography

We applied the technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) split-dose method in order to evaluate the feasibility of assessing cerebral blood flow (CBF) changes with single photon emission tomography (SPET) during a motor activation task. Eleven normal subjects were studied using the Tomomatic 564 (Medimatic, DK). Five subjects were studied twice at rest and 6 subjects at rest and during a motor task performance (finger opposition movements). A total of 28 mCi of ^99mTc-HMPAO was injected in 2 doses with a 1:3 ratio. The first scan was obtained after injection of 7 mCi at rest in all subjects. The second scan was obtained a few minutes later, after injection of the remaining dose (21 mCi), under similar resting conditions or during a motor task performance. The mean brain uptake was proportional to the amount of tracer injected and to the acquisition time for both the first scan (5263±1266 counts × mCi × min) and the second (5034.4±966 counts × mCi × min). The grey/white matter ratio was 1.67±0.019 and 1.67±0.097 for the two scans, respectively. A three-way analysis of variance (ANOVA) for repeated measure showed no significant effects of side, slice and region of interest (ROI) on the CBF in the 5 subjects studied twice at rest, and the mean regional CBF change was –0.2%±5%. In the 6 subjects studied at rest and during motor activation, the image subtraction analysis showed a significant CBF increase in the primary motor cortex contralateral to the stimulated side (15%±7%, n=6) and medially in the supplementary motor area (22%±12%, n=4). Our results indicate that the split-dose method allows the detection of a local CBF response to motor activation using ^99mTc-HMPAO in a single imaging session. Correspondence to: P. Pantano     

Demonstration of reperfusion after thrombolysis with technetium-99m isonitrile myocardial imaging

Technetium-99m isonitrile myocardial perfusion imaging was employed in a patient undergoing thrombolytic therapy with recombinant tissue plasminogen activator for acute anteroseptal myocardial infarction. Technetium-99m isonitrile does not demonstrate significant myocardial redistribution after intravenous injection. The imaging agent was administered in the emergency room, prior to the initiation of thrombolytic therapy. The initial area at risk for infarction was visualized on images obtained after the patient had been effectively treated. Imaging performed 5 days later, after repeat injection of [99mTc]isonitrile, showed a smaller myocardial perfusion defect indicating salvage of myocardium. Thus, this technique offers promise as a noninvasive means of assessing the area at risk, the success of reperfusion, and the presence of salvaged myocardium, early in the course of acute myocardial infarction.     

Quantification of myocardial ischemia and infarction with single photon emission computed tomography

To evaluate the feasibility of ²⁰¹Tl single photon emission computed tomography (SPECT) for quantitative detection of myocardial infarction and ischemia, scintigraphic studies were related to angiographic findings. In study A infarct sizes with SPECT were compared with the angiographic infarct sizes of 30 patients. A linear correlation was found for the % infarct of the left ventricular circumference between both methods (r=0.73; P< 0.001; mean infarct size 20.7%±10.5% (angio) vs 19.8%±12.9% (SPECT), mean±SD). Furthermore, a significant inverse correlation between scintigraphic infarct size and left ventricular ejection fraction (r=-0.87, P< 0.001) was obtained. In study B exercise/rest ²⁰¹Tl SPECT was used for quantification of myocardial ischemia. Forty-three patients underwent both stress ²⁰¹Tl SPECT and biplane exercise left ventriculography. Ischemia was expressed as % defect size of the left ventricular circumference. Sensitivity and specificity for detection of ischemia were 96% and 100% respectively with stress SPECT. Extent of myocardial ischemia correlated significantly with both methods (r=0.63; SPECT defect=1.0 angiographic ischemia +2%; P< 0.001). The regression followed the line of identity and the mean sizes of ischemia were identical (SPECT 12.2±7.6% vs 14.6±12.4% ventriculography, mean±SD) demonstrating the agreement of both methods. However, there was some intraindividual variance between the scintigraphic and the angiographic study. The sensitivity and specificity in single regions with SPECT were lower compared to the global test results. The correlation between the non invasive SPECT and the ventriculography in detection of myocardial infarction and ischemia indicates the clinical value of ²⁰¹Tl SPECT for diagnosis of coronary heart disease.Parts of the results were presented at the 58th sessions of the American Heart Association at Washington, DC (1985)     

Quantification of myocardial ischemia and infarction with single photon emission computed tomography

To evaluate the feasibility of 201Tl single photon emission computed tomography (SPECT) for quantitative detection of myocardial infarction and ischemia, scintigraphic studies were related to angiographic findings. In study A infarct sizes with SPECT were compared with the angiographic infarct sizes of 30 patients. A linear correlation was found for the % infarct of the left ventricular circumference between both methods (r = 0.73; P less than 0.001; mean infarct size 20.7% +/- 10.5% (angio) vs 19.8% +/- 12.9% (SPECT), mean +/- SD). Furthermore, a significant inverse correlation between scintigraphic infarct size and left ventricular ejection fraction (r = -0.87, P less than 0.001) was obtained. In study B exercise/rest 201Tl SPECT was used for quantification of myocardial ischemia. Forty-three patients underwent both stress 201Tl SPECT and biplane exercise left ventriculography. Ischemia was expressed as % defect size of the left ventricular circumference. Sensitivity and specificity for detection of ischemia were 96% and 100% respectively with stress SPECT. Extent of myocardial ischemia correlated significantly with both methods (r = 0.63; SPECT defect = 1.0 angiographic ischemia +2%; P less than 0.001). The regression followed the line of identity and the mean sizes of ischemia were identical (SPECT 12.2 +/- 7.6% vs 14.6 +/- 12.4% ventriculography, mean +/- SD) demonstrating the agreement of both methods. However, there was some intraindividual variance between the scintigraphic and the angiographic study. The sensitivity and specificity in single regions with SPECT were lower compared to the global test results.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison between exercise and trans-oesophageal atrial pacing in patients with coronary artery disease: technetium-99m methoxy isobutyl isonitrile simultaneous evaluation of ventricular function and myocardial perfusion

In this study we compared the results of exercise and trans-oesophageal atrial pacing (TAP) technetium-99m methoxyisobutyl isonitrile (^99mTc-SESTAMIBI) cardiac imaging in the evaluation of left ventricular (LV) function and myocardial perfusion in patients with angiographically proven coronary artery disease. Ten patients (8 men and 2 women, mean age 59 ± 6 years) were submitted to 3 separate injections of ^99mTc-SESTAMIBI, one under control conditions, one after exercise and one after TAP. LV ejection fraction, as measured by electrocardiogram (ECG) gated first pass, decreased from 49 ± 5 % under control conditions to 42 ±6% during exercise (P < 0.05 versus control) and to 43 ±8 % during TAP (P<0.05 versus control and insignificant change versus exercise). Segmental myocardial perfusion analysis was performed on a total of 150 myocardial segments. On both exercise and TAP ^99mTc-SESTAMIBI studies, 103 segments (69% of the total) were normal, 32 (21 %) had reversible, and 15 (10%) irreversible, perfusion defects. Relative regional tracer uptake was not statistically different between exercise and TAP in normal regions (91.1 ± 9.1 % versus 90.7 ± 8.5 %, respectively), in regions with reversible (61.9±12% versus 62.4±10.4%, respectively) and irreversible perfusion defects (55.8 ± 7.8 % versus 58.8 ± 9.5 %, respectively). Our results demonstrated that ^99mTc-SESTAMIBI TAP cardiac imaging shows similar results to ^99mTc-SESTAMIBI exercise myocardial scintigraphy in the assessment of LV function and myocardial perfusion in patients with coronary artery disease.This work was partially supported by a grant from the Italian National Council of Research (CNR) (Special Project Immagini Biomediche in-Vivo)     

Motor stimulation response by technetium-99m hexamethylpropylene amine oxime split-dose method and single photon emission tomography.

We applied the technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) split-dose method in order to evaluate the feasibility of assessing cerebral blood flow (CBF) changes with single photon emission tomography (SPET) during a motor activation task. Eleven normal subjects were studied using the Tomomatic 564 (Medimatic, DK). Five subjects were studied twice at rest and 6 subjects at rest and during a motor task performance (finger opposition movements). A total of 28 mCi of 99mTc-HMPAO was injected in 2 doses with a 1:3 ratio. The first scan was obtained after injection of 7 mCi at rest in all subjects. The second scan was obtained a few minutes later, after injection of the remaining dose (21 mCi), under similar resting conditions or during a motor task performance. The mean brain uptake was proportional to the amount of tracer injected and to the acquisition time for both the first scan (5263 +/- 1266 counts x mCi x min) and the second (5034.4 +/- 966 counts x mCi x min). The grey/white matter ratio was 1.67 +/- 0.019 and 1.67 +/- 0.097 for the two scans, respectively. A three-way analysis of variance (ANOVA) for repeated measure showed no significant effects of side, slice and region of interest (ROI) on the CBF in the 5 subjects studied twice at rest, and the mean regional CBF change was -0.2% +/- 5%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison between exercise and trans-oesophageal atrial pacing in patients with coronary artery disease: technetium-99m methoxy isobutyl isonitrile simultaneous evaluation of ventricular function and myocardial perfusion.

In this study we compared the results of exercise and trans-oesophageal atrial pacing (TAP) technetium-99m methoxyisobutyl isonitrile (99mTc-SESTAMIBI) cardiac imaging in the evaluation of left ventricular (LV) function and myocardial perfusion in patients with angiographically proven coronary artery disease. Ten patients (8 men and 2 women, mean age 59 +/- 6 years) were submitted to 3 separate injections of 99mTc-SESTAMIBI, one under control conditions, one after exercise and one after TAP. LV ejection fraction, as measured by electrocardiogram (ECG) gated first pass, decreased from 49 +/- 5% under control conditions to 42 +/- 6% during exercise (P less than 0.05 versus control) and to 43 +/- 8% during TAP (P less than 0.05 versus control and insignificant change versus exercise). Segmental myocardial perfusion analysis was performed on a total of 150 myocardial segments. On both exercise and TAP 99mTc-SESTAMIBI studies, 103 segments (69% of the total) were normal, 32 (21%) had reversible, and 15 (10%) irreversible, perfusion defects. Relative regional tracer uptake was not statistically different between exercise and TAP in normal regions (91.1 +/- 9.1% versus 90.7 +/- 8.5%, respectively), in regions with reversible (61.9 +/- 12% versus 62.4 +/- 10.4%, respectively) and irreversible perfusion defects (55.8 +/- 7.8% versus 58.8 +/- 9.5%, respectively). Our results demonstrated that 99mTc-SESTAMIBI TAP cardiac imaging shows similar results to 99mTc-SESTAMIBI exercise myocardial scintigraphy in the assessment of LV function and myocardial perfusion in patients with coronary artery disease.     

Cerebral infarction pattern identified on emission computed tomography using technetium-99m MDP

In the metastatic work-up of a patient with a malignant lung tumor and cerebrovascular disease, bone imaging was performed which showed abnormal uptake in the right parietal region. Emission computed tomography indicated that this was due to intracranial disease and revealed a wedge-shaped pattern indicative of cerebral infarction. A later follow-up study showed complete clearance of the abnormal uptake.     

Evaluation of myocardial perfusion and function by single photon emission computed tomography

Although planar radionuclide techniques provide accurate, noninvasive measurements of myocardial perfusion and function that are of proven clinical value in the evaluation of the cardiac patient, they are limited by poor object contrast and superimposition of surrounding structures. Due to incomplete angular sampling and significant longitudinal distortion, limited angle tomography did not solve these problems. Single photon emission computed tomography (SPECT) can acquire scintillation information over very small angles of rotation and, thus, improve both object contrast and delineation of overlying or adjacent structures without distortion. The early SPECT systems were cumbersome, dependent on individual user developed software, and had extremely long acquisition and processing time. Improved camera design, new software algorithms, and the use of array processors have simplified and standardized quality control, decreased processing time, and minimized the number of user interventions. New image display formats and quantitative methods of analysis have made interpretation less cumbersome, more reliable and highly reproducible. Cardiac SPECT has been used with thallium-201 and gated blood pool imaging in both research and clinical applications and shown an improvement over planar methods of acquisition.