ECG-gated dual-isotope myocardial SPECT with 201Tl and 99mTc-tetrofosmin: simultaneous assessment of stress/rest myocardial perfusion and left ventricular function

ECG-gated dual-isotope acquisition protocol involving rest imaging with 201Tl and stress 99mTc-tetrofosmin (TF) SPECT was designed for the simultaneous assessment of rest/stress myocardial perfusion and rest ventricular systolic function. This study assessed the feasibility and diagnostic accuracy of this protocol. Forty-five patients underwent the dual-isotope SPECT protocol. Twenty minutes after resting injection of 111 MBq of 201Tl, 370 MBq of 99mTc-TF was administered at a peak exercise. The dual-isotope gated SPECT acquisition was performed 1 hour later. Then, the regional count increase rate (%WT) of 99mTc-TF from end-diastole end-systole was calculated using an automated method which was developed for quantification of regional wall thickening based on circumferential profile analysis in our laboratory. Myocardial perfusion and contractility analysis was carried out using 8 segments of left ventricle with comparison of coronary angiographical findings. The sensitivity and specificity for the detection of diseased coronary vessels (> = or 75% stenosis) were 76% and 94%, respectively. Infarcted regions showing reversible defect had significantly greater %WT as compared with those with fixed defects (63 seg; 12.7 +/- 6.1% vs. 36 seg; 8.9 +/- 7.2%, p < 0.01). In conclusion, this dual-isotope protocol has some advantages; i.e., shortening an examination time, having the exact registration of stress/rest perfusion, and simultaneous evaluation of resting regional wall thickening.     

Stress and rest myocardial SPET quantification with 201Tl and 99Tcm-tetrofosmin: a comparison

99Tcm-tetrofosmin is a new myocardial perfusion agent that has excellent physical and pharmacokinetic characteristics for performing tomographic myocardial perfusion studies. The aim of this study was to compare the behaviour of 99Tcm-tetrofosmin and 201Tl in the assessment of ischaemia and viability in patients with previous myocardial infarction. Twenty consecutive patients who had suffered infarction and been referred for assessment of ischaemia and myocardial viability were enrolled into the study. Each patient underwent two stress tests performed no more than 10 days apart, one with a 201Tl exercise-reinjection-redistribution method and one with a 99Tcm-tetrofosmin short protocol (exercise-rest). The results were quantified using polar maps to represent images for stress, rest and reversibility. The post-stress images showed there was a slight tendency to overestimate defect size with 99Tcm-tetrofosmin in the lateral region (P < 0.006). We found no significant differences between the two tracers when comparing reversibility. The same defect size at rest were obtained when the maps for 201Tl with uptake of 50% were compared with those for 99Tcm-tetrofosmin with uptake of 45%. Agreement between the two agents for assessment of viability was 93%. We conclude that the quantitative assessment of myocardial ischaemia and uptake of 99Tcm-tetrofosmin at rest are comparable to those obtained with 201Tl in patients who have suffered myocardial infarction.     

Detection of lung and chest tumours using 99Tcm-tetrofosmin: comparison with 201Tl

The aim of this study was to assess the usefulness of 99Tcm-tetrofosmin for detecting tumours of the lungs and adjacent structures and to compare the results with those for 201Tl. In the 18 patients studied, there were 30 lesions in total. Dual-isotope SPET acquisitions were performed 10 min and 3 h after the administration of 99Tcm-tetrofosmin and 201Tl. Image quality and semi-quantitative parameters were evaluated for both tracers. All lesions were detected by the two radiopharmaceuticals on both the early and delayed images. In seven patients, the image quality of 99Tcm-tetrofosmin was better than that of 201Tl. For the detection of metastatic lymph nodes, the delayed 201Tl and the early 99Tcm-tetrofosmin images were superior. No significant difference was observed between the uptake ratios of the two tracers. 99Tcm-tetrofosmin showed significantly (P < 0.001) higher washout than 201Tl from both the lesions and normal lungs, although washout of 201Tl from normal lungs was significantly higher than that from the lesions. In conclusion, 99Tcm-tetrofosmin may be helpful for detecting tumours of the lungs and adjacent structures, but has limited applicability in differentiating between malignant and benign tumours and may not be used instead of 201Tl to detect malignant tumours of the lungs.     

Evaluation of brain tumor by 99mTc-MIBI: comparison study with 201Tl and predictivity of therapeutic effect

Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR of genomic DNA. When these sequences are compared with each other and the previously published Spidroin 1 sequence, there are differences due to sequence rearrangements, as well as single base substitutions. These variations are similar to those that have been reported from other highly repetitive genes, and probably represent the results of unequal cross-overs. We have also obtained 708 bp of sequence from pCR of genomic DNA from Araneus biocentenarius. This sequence shows considerable similarity to a dragline sequence (ADF-3) from A. diadematus, as well as Spidroin 2 (NCF-2) from N. clavipes. Minor but consistent differences in the repeating unit sequence between A. bicentenarius and A. diadematus suggest that concerted evolution or gene conversion processes are acting to maintain similarity among repeat units within a single gene.     

Combined scatter and attenuation correction for 201Tl myocardial perfusion SPECT using OS-EM algorithm

There are two possible ways to obtain scatter-corrected images with the ML-EM (maximum likelihood expectation maximization) algorithm: one is the subtraction of scatter estimate si from projection data pi, and then (pi-si) is used for scatter-corrected projection data (denoted as SC(T)); the other method is the addition of scatter estimate si to the projections calculated from the reconstructed image without performing data subtraction (SC(E)). This paper investigated these two ML-EM algorithms of combined scatter and attenuation correction on 201Tl myocardial perfusion SPECT imaging. Scatter windows were placed one full width at half maximum (FWHM) below and above the photopeak centerline. The scatter fraction in the primary peak was estimated using trapezoidal approximation by the triple energy window method. Phantom and clinical images were reconstructed using 6 iterations of ordered subsets EM algorithm (OS-EM). A cylindrical phantom with a cold-rod insert and a heart/thorax phantom with liver insert were used to evaluate scatter and the attenuation compensation technique. A cylindrical phantom filled with uniform 201Tl solution was used to evaluate statistical noise. The percent root-mean-square uncertainty (%RMSU) was used as a quantitative measure of noise amplification. %RMSU showed that the SC(E) method amplified noise less in comparison with the SC(T) method, however, no significant difference in image quality was observed between the two methods. In conclusion, both the SC(T) and SC(E) methods provided significant and similar improvement in the removal of scatter in 201Tl myocardial perfusion SPECT imaging.     

Myocardial uptake of 99mTc-tetrofosmin, sestamibi, and 201Tl in a model of acute coronary reperfusion

BACKGROUND: To investigate whether tetrofosmin uptake is affected by myocardial viability as has been noted for 201Tl and sestamibi, we analyzed the initial and delayed distribution patterns of tetrofosmin in a rat coronary artery occlusion-reperfusion model. METHODS AND RESULTS: Animals were intubated and ventilated, and their arterial pressures were monitored. A left thoracotomy was performed. After 1-hour occlusion and 1-hour reperfusion of a major branch of the circumflex artery, 201Tl and either tetrofosmin or sestamibi were injected intravenously. Radiolabeled microspheres were used to document the area at risk and reperfusion. Five minutes or 1 hour after administration of the diffusible tracers, the animals were killed. Tracer distribution was determined by use of segmental tissue analysis, and tissue viability was determined by use of histochemical staining. Both the initial and delayed retention of tetrofosmin were sensitive to myocardial viability, as shown by significantly lower uptake (30 +/- 14%) and retention (24 +/- 12%) of tetrofosmin in the nonviable segments compared with the viable segments. In addition, the initial myocardial distribution of tetrofosmin was similar to that noted for 201Tl, but after 1 hour of tracer circulation, the tetrofosmin tissue distribution appeared unchanged compared with the initial regional blood flow distribution. This is in direct contrast to our present observations of significant 201Tl redistribution and some changes in sestamibi distribution as well. CONCLUSIONS: The clinical implication of these observations suggests that initial and delayed imaging after tetrofosmin administration would reflect both the initial regional blood flow pattern and myocardial viability.     

Identification of viable myocardium by 201Tl scintigraphy: a comparison of methods

The present study was undertaken to compare four different imaging approaches to evaluate uptake defect reversibility. 24 infarcted patients underwent standard stress/redistribution 201Tl imaging (R1). Then, after reinjection of 37 MBq of 201Tl, patients were re-imaged either after 15 min (R2) 24 h later (R3). A separate rest study (R4) following a new tracer injection was done within 2-3 days. Planar images were obtained in the standard three views and subdivided into 216 segments for qualitative analysis based on a visual score. A semiquantitative analysis based upon circumferential profiles was also applied. A stress defect was found in 127 segments (58.7%). By visual inspection reperfusion was considered to occur in 32.3%, 41.7%, 33.0% and 49.6% of the cases with R1, R2, R3, and R4, respectively. The semiquantitative method showed a high reperfusion only with R1 (62%), while the other procedures proved less effective. No improvement was found with R4. Six patients (25%) showed myocardial viability that was not detected with the early reinjection technique.     

Rest and stress myocardial perfusion imaging on the same day with two injections of 99mTc-tetrofosmin

99mTc-tetrofosmin myocardial perfusion imagings under different protocols were performed at rest and stress on the same day. In the stress/rest protocol, the exercise study was carried out first, and then the rest one followed. Eight patients were involved in the stress/rest protocol. Seven patients were examined in the reverse, rest/stress protocol. In any protocols, the injection interval was 3 hours, and injection doses in the first and second studies were 370 MBq and 740 MBq, respectively. Myocardial counts were obtained by placing region of interest over the myocardial walls in short axial SPECT images. Based on myocardial counts from the first injection and the wash-out rate of tetrofosmin, we calculated, at the second imaging, counts caused from the first injection. Approximately 20-25% of counts in the second study were found to be caused from the residual radiotracer. The residual radiotracers affected the interpretation of imagings of two patients we examined: one with marked reversible ischemia examined in the stress/rest protocol and the other with mild ischemic change examined in the rest/stress one. Our results suggested that some modifications of studies, such as the increase in the injection intervals or the reduce of the first-to-second dose ratio, might be necessary to conduct the same day protocols.     

123I-MIBG myocardial scintigraphy in diabetic patients: relationship with 201Tl uptake and cardiac autonomic function

The purpose of this study is to investigate the effects of aging on the human stretch reflexes. The EMG and torque responses of the stretch reflex of the wrist flexors were evoked by ramp-and-hold mechanical perturbations. The stretch reflexes were recorded at seven test conditions with different stretch velocity and muscle preload. The test results from young and older healthy adult subjects were compared. In average, the absolute amplitude of the short-latency (20-40 ms) EMG (recorded from flexor carpi radialis) reflex response was significantly lower in the older group. If the data were normalized and expressed in percentage of the maximal voluntary EMG activity, however, this group difference was not significant. There was no change in the reflex gain of the short-latency reflex with aging. For the long-latency (50-90 ms) EMG reflex response, both the normalized amplitude and the reflex gain were significantly enhanced with aging, probably through supraspinal mechanisms. There was no significant difference in the threshold velocity for the evoked EMG reflexive activities between age groups. There were also no changes in the reflexive wrist flexion torque with aging. These results suggested that the number of motor units recruited during the stretch reflex activity declined with aging although the percentage of motor units recruited was not affected by aging. It is concluded that the central regulating mechanisms of the spinal motoneuron excitability are not compromised by aging. The automatic gain compensation phenomenon is also preserved with aging.     

Evaluation of left ventricular systolic function using cine MRI--application to hypertrophic cardiomyopathy

Cine MRI is a useful means to analyse the anatomical and functional changes of hypertrophic cardiomyopathy. The visual evaluation of hypertrophic regions and the motion patterns of their walls is in most cases possible on cine MR images. To complement a subjective method a certain quantitative analysis is necessary. Left ventricular regional systolic function can be quantitatively evaluated using cine MRI images printed on films. There is a good correlation between % thickness of LV wall and its thickness at end diastolic phase. The comparison of % thickness of normal subjects with that of hypertrophic cardiomyopathies shows a tendency of its value being less at the region of more severe hypertrophic change.     

Effects of diltiazem on myocardial perfusion abnormalities during exercise in patients with hypertrophic cardiomyopathy

We developed a novel chemiluminescent assay of beta-D-galactosidase (beta-gal) based on the chemiluminescence of indole. 5-Bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) was used as a substrate for beta-gal and also as a light emitter. X-gal was hydrolysed by beta-gal to liberate free indoxyl, followed by oxidation to indigo dye, and simultaneously produces hydrogen peroxide (H2O2). H2O2 reacts with the residual X-gal in the presence of horseradish peroxidase (HRP) to emit light. The measurable range of beta-gal obtained by this method was 6 x 10(-14) mol/L to 6 x 10(-11) mol/L; the detection limit was 3 amol/assay. This chemiluminescent assay could be applied to an enzyme immunoassay of thyroxine using beta-gal as the enzyme label.     

Myocardial uptake and redistribution of 99mTc-N-NOET in dogs with either sustained coronary low flow or transient coronary occlusion: comparison with 201Tl and myocardial blood flow

BACKGROUND: 99mTc-N-NOET (NOET) is a new myocardial perfusion imaging agent that redistributes over time. We sought to better define the redistribution kinetics of NOET using open-chest canine models of sustained low coronary flow (protocol 1) and transient coronary occlusion followed by reflow (protocol 2). METHODS AND RESULTS: In protocol 1 (n=10), NOET and 201Tl were injected during low flow in the left anterior descending coronary artery (LAD) that was sustained for 2 hours. Protocol 2 dogs (n=6) were injected with NOET during 20 minutes of LAD occlusion followed by 2 hours of reflow. In both protocols, serial NOET planar images were acquired, and myocardial flow and 2-hour tracer activities were determined by gamma-well counting. Defect resolution was observed on images in both protocols. Initial defect count ratios, reflecting flow disparity at injection (0.66+/-0.03 and 0.57+/-0.04, respectively), increased over 2 hours (0.73+/-0.02 and 0.75+/-0.04, respectively; P<.001 versus initial). Quantitative imaging showed that NOET redistribution resulted from greater clearance from normal areas versus low-flow or transiently occluded areas. In protocol 1, 2-hour NOET and 201Tl stenotic-to-normal tissue activity ratios were similar (0.76+/-0.06 versus 0.73+/-0.04, P=NS) and higher than injection flow ratios (0.52+/-0.06 and 0.56+/-0.07, respectively, P<.001), consistent with tracer redistribution. In protocol 2, NOET redistributed to an even greater extent (injection flow ratio, 0.27+/-0.04; 2-hour tissue activity ratio, 0.84+/-0.03, P<.001). CONCLUSIONS: NOET is the first 99mTc-labeled myocardial imaging agent with kinetics similar to 201Tl in experimental models, permitting redistribution imaging. NOET appears to be a promising agent for assessing patients with coronary artery disease.     

The 24-hour Tl-201 image in dual isotope myocardial perfusion scintigraphy: clinical utility and prognostic significance

This study assessed the effect on clinical decision making and the possible prognostic significance of the 24-hour Tl-201 image in patients undergoing Tl-201-MIBI dual-isotope myocardial scintigraphy. The records of all patients who underwent 24-hour Tl-201 imaging as part of their myocardial perfusion study from 1994 to 1996 were reviewed. Follow-up evaluations were obtained from the referring physician or by direct patient contact. Fifty-six patients underwent a total of 57 studies; four patients were lost to follow-up. Of the 53 studies evaluated, 29 showed no change between the standard rest images and the 24-hour images; these patients were reported to have myocardial scar. Of these 29 patients, 25 were treated medically without further evaluation; 24 of these 25 patients remained stable. Four of the 29 patients had further evaluation; 2 patients had coronary artery bypass graft, 1 had a stent placed, and 1 remained stable. Twenty-four patients showed definite improvement or normalization of their study results by 24 hours; they were reported as ischemic. Of these 24 patients, 11 were treated medically without further evaluation; 9 remained stable, whereas 2 had adverse events. The remaining 13 patients required further evaluation; 4 remained stable, whereas 9 had adverse events (4 = increasing angina; 1 = stent; 1 = rotoblator; 2 = percutaneous transluminal coronary angioplasty; 1 = death). Twenty-four-hour imaging contributes to clinical decision making and may identify a subset of patients at risk for subsequent complications.     

Right ventricular function in patients with dilated cardiomyopathy: assessment using krypton-81 m blood pool scintigraphy

The characteristics and pathogenesis of right ventricular dysfunction in 14 patients with dilated cardiomyopathy (DCM) were investigated by equilibrium right ventricular blood pool scintigraphy using ultrashort-lifetime 81mKr. Thirteen patients with severe left ventricular dysfunction due to old anterior myocardial infarction (OMI) and nine normal subjects were used as controls. The right ventricular end-diastolic pressure and volume index, mean pulmonary arterial pressure, and total pulmonary vascular resistance index were almost the same in the DCM and OMI patients. The right ventricular ejection fraction was 44.2 +/- 6.0% (mean +/- SD) in DCM patients and 47.1 +/- 7.9% in OMI patients, both significantly lower than those in the normal subjects (54.5 +/- 5.3%), but with no difference between the two case groups. The right ventricular peak filling rate was significantly reduced in both case groups as compared with the normal subjects (2.46 +/- 0.81 EDV/sec). The reduction was significantly greater (p < 0.05) in the DCM group (0.97 +/- 0.47 EDV/sec) than in the OMI group (1.61 +/- 0.46 EDV/sec). Cineangiography showed that the wall motion abnormality of the interventricular septum was remarkable in OMI patients, but was relatively mild in DCM patients. Lesions of the interventricular septum may be of major importance in right ventricular dysfunction in OMI, while extensive severe damage to the right ventricular free wall may be important in DCM. 81mKr blood pool scintigraphy is useful in the study of the right ventricular systolic and diastolic function. The diastolic parameters are more sensitive indicators for evaluation of right ventricular function in DCM than the systolic parameters.     

Scintigraphic assessment of silent myocardial ischaemia after early infarction using myocardial SPET imaging with 201Tl and 123I-MIBG

To test the hypothesis that myocardial sympathetic denervation reflects silent myocardial ischaemia early after infarction, 12 patients with myocardial infarction but without post-infarction angina pectoris underwent single photon emission tomography (SPET) at rest with 201Tl and 123I-metaiodobenzylguanidine (MIBG) shortly after and 3 months after infarction. Short-axis SPET images at the basal, mid-ventricular and apical portions of the left ventricle were selected, and each short-axis image was divided into eight segments. Tracer uptake in each of the 24 segments was scored using a 4-point scale. The total score in each segment was calculated as the defect score for each image, and the difference between the total defect score for the 201Tl and 123I-MIBG images was calculated as the delta defect score. All 12 patients underwent exercise stress 201Tl scintigraphy 1 month after infarction, and they were divided into two groups: those patients with (Group A, n = 7) and those patients without (Group B, n = 5) transient perfusion defects in the peri-infarcted region without chest pain. For the 123I-MIBG defect score, a marked reduction at 3 months was observed in Group A (24 +/- 12 vs 13 +/- 6; P < 0.01), whereas the defect score remained unchanged in Group B (25 +/- 7 vs 23 +/- 8; N.S.). The delta defect score was significantly reduced in Group A (10 +/- 5 vs 6 +/- 4; P < 0.05), whereas it remained unchanged in Group B. The 123I-MIBG defect score early after infarction was higher than the exercise-induced 201Tl defect score (24 +/- 12 vs 20 +/- 9; P < 0.01), whereas at 3 months post-infarction it was lower than the exercise-induced 201Tl defect score (13 +/- 6 vs 20 +/- 9; P < 0.05). Moreover, effort chest pain during daily activities was noted in 5 of the 7 (71%) patients in Group A within 3 months post-infarction. The results of this study suggest that viable but denervated myocardium (mismatched 123I-MIBG defects) is present in peri-infarcted regions, and that myocardial sensory nervous disturbance, which may co-exist with sympathetic nervous denervation, may induce silent myocardial ischaemia in patients with myocardial infarction.     

Attenuation-corrected 99mTc-tetrofosmin single-photon emission computed tomography in the detection of viable myocardium: comparison with positron emission tomography using 18F-fluorodeoxyglucose

OBJECTIVES: The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (99mTc)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). BACKGROUND: The role of 99mTc-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images. METHODS: Twenty-four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting 99mTc-tetrofosmin SPECT and FDG PET imaging. Both AC and non-attenuation-corrected (NC) SPECT images were generated. RESULTS: Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between 99mTc-tetrofosmin and FDG on the patient basis increased from 79.8%+/-14.0% (mean+/-SD) on the NC images to 90.8%+/-10.6% on the AC images (p=0.002). The percentage of 99mTc-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8%+/-15.2% on the NC images to 9.7%+/-12.6% on the AC images (p=0.01). Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior-septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region. CONCLUSIONS: The results indicate that AC 99mTc-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior-septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction.     

Superiority of nitrate-enhanced 201Tl over conventional redistribution 201Tl imaging for prognostic evaluation after myocardial infarction and thrombolysis

BACKGROUND: 201Tl imaging has been widely used for postinfarction risk stratification. However, thrombolytic therapy and aspirin have significantly changed outcome, and there are few nuclear imaging studies that assess prognosis in such patients. Furthermore, newer techniques of 201Tl imaging, such as reinjection and nitrate-enhanced rest 201Tl imaging, have been shown to improve the detection of viable but jeopardized myocardium. METHODS AND RESULTS: We studied 100 consecutive patients, who remained event free 6 weeks after myocardial infarction and thrombolysis. Patients underwent conventional exercise and 4-hour redistribution imaging, followed on a separate day by nitrate-enhanced rest 201Tl study. Planar images were reported semiquantitatively by two experienced observers blinded to clinical data. Redistribution and rest injection images were classified as demonstrating reversible ischemia if they showed improvement in uptake by at least two grades in at least two segments in comparison with the initial exercise scintigram. Patients were followed up for 8 to 32 months (mean, 21 months); during this period, 37 patients had first cardiac events. Reversible ischemia was present in 29 patients on redistribution, of whom 14 (48%) had events; of 71 without reversible defects, 23 (32%) had events (hazard ratio, 1.5; 95% CI, 0.8 to 3.0; P=NS). Nitrate-enhanced rest 201Tl imaging detected reversible defects in 68 patients, of whom 33 (49%) had events, whereas of 32 without reversible defects, only 4 (13%) had subsequent cardiac events (hazard ratio, 8.1; 95% CI, 2.7 to 23.8; P<.001). CONCLUSIONS: Thus, after myocardial infarction and thrombolysis, even "stable" patients have a high (68%) incidence of viable but jeopardized myocardium, causing a high event rate. Those identified to be at high risk by perfusion imaging may benefit from early intervention.     

Evaluation of the automatic quantification of left ventricular function using ECG gated 99mTc-MIBI myocardial SPECT

OBJECTIVE: To compare temporal changes in body mass index (BMI) (kg/m2) and prevalence of obesity (BMI > 25 and > 30 kg/m2) among adult Kuwaitis between two periods 14 y apart. DESIGN: Comparison of two independent cross-sectional samples of Kuwaitis studied in 1980-1981 and 1993-1994. SUBJECTS: 2067 (896 men and 1171 women) and 3435 (1730 men and 1705 women) adult Kuwaitis (aged > or = 18 y), drawn from primary health care (PHC) clinics and studied for nutritional assessment and for prevalence of obesity in 1980-1981 and 1993-1994, respectively. MEASUREMENTS: BMI, which is the weight in kilograms divided by the height in meters squared (kg/m2), was based on measured weight and height. Obesity was defined as BMI > 25 kg/m2 (grade 1) and BMI > 30 kg/m2) (grade 2). RESULTS: Mean BMI increased significantly (P < 0.001) by 10.0% and 6.2% (2.5 and 1.7 kg/m2) among men and women, respectively. Prevalence of obesity (BMI > 25 and > 30 kg/m2) increased by 20.6% and 15.4% and by 13.7% and 8.4% among men and women, respectively. After controlling for sociodemographic differences between the two study periods, BMI was 2.0 and 1.6 kg/m2 higher in 1993-1994 than in 1980-1981 among men and women respectively. The risk of obesity (BMI > 25 and > 30 kg/m2) also increased among both genders between the two periods (OR = 2.1, 95% CI 1.7-2.7 and OR = 1.9, 95% CI 1.5-2.4, for men and OR = 2.2, 95% CI 1.6-3.0 and OR = 1.4, 95% CI 2.2 CI-1.0-1.9, for women). CONCLUSION: BMI and prevalence of obesity increased among Kuwaitis between 1980-1981 and 1993 and 1994 probably due to the effects of modernization, affluence, increased food consumption and the concomitant changes to sedentary lifestyles. The rate of temporal changes in BMI and obesity were higher, by comparison, in Kuwait than in selected other countries.     

Technetium-99m-MIBI and thallium-201 scintigraphy of primary lung cancer

We evaluated the usefulness of 99mTc-MIBI scintigraphy in primary lung cancer in comparison with 201Tl-chloride scintigraphy. METHODS: There were 45 patients with primary lung cancer. All patients underwent dual-isotope imaging with 201Tl-chloride and 99mTc-MIBI. Regions of interest were placed over the tumors (T) and contralateral normal lung tissue (N) on one coronal view in the SPECT, and T/N ratio and retention index were calculated. RESULTS: The positive rate was 98% in both the early and delayed images for 201Tl-chloride and 96% in the early and 89% in the delayed image for 99mTc-MIBI. Both early and delayed T/N ratios for 201Tl-chloride were higher than those for 99mTc-MIBI. There was no significant correlation between T/N ratio and histological type of tumor in both images. However, in both images, there was a tendency for the early and delayed ratios to increase as the tumor diameter became larger. The retention index of 201Tl-chloride was higher than that of 99mTc-MIBI. There were no significant differences in the retention index with respect to the histological type and tumor size. CONCLUSION: The results of this preliminary clinical study suggest that 99mTl-MIBI can depict primary lung cancer similar to 201Tl-chloride. However, T/N ratio and retention index of 99mTc-MIBI in the tumor areas are significantly lower compared with those of 201Tl-chloride.