Fast acquisition of myocardial SPECT images with Tc-99m sestamibi for the diagnosis of coronary artery disease

BACKGROUND: Shortening the acquisition time for myocardial single-photon emission computed tomographic (SPECT) imaging increases patient comfort and laboratory throughput. The purpose of this study was to compare the diagnostic accuracy for coronary artery disease detection of myocardial SPECT images acquired in 5 to 10 minutes versus 25 minutes using Tc-99m methoxyisobutylisonitrile (Tc-99m sestamibi) and a single-head gamma camera. METHODS AND RESULTS: Forty-one subjects had a standard 1-day rest/stress Tc-99m sestamibi myocardial SPECT study. Two sets of rest and stress images were acquired on the same day for each subject. One set of images was acquired with a 5- to 10-minute fast acquisition protocol; the second set of images was acquired with a 25-minute standard protocol. The accuracies of the fast and standard protocols for identifying individuals with and without coronary artery disease were equivalent. Accuracy was 76% for the fast protocol and 73% for the standard protocol in individuals with at least one coronary stenosis > or = 70%. The accuracies of the two protocols for identifying individual coronary arteries with stenoses > or = 70% also were equivalent. Accuracy was 77% for the fast protocol and 74% for the standard protocol. CONCLUSIONS: SPECT myocardial images may be acquired in as little as 5 to 10 minutes using Tc-99m sestamibi and a 1-day rest/stress protocol. Accuracy is equivalent to that attained in studies with longer imaging times.     

Stress myocardial gammatomography in the diagnosis of multivessel coronary disease

OBJECTIVE: The aim of the study was to evaluate the diagnostic yield of 99m-Technetium-methoxy-isobutyl-isonitrile (MIBI) SPET for identification of individual coronary artery disease and in the prediction of multivessel involvement. METHODS: Stress/rest myocardial SPET and coronary arteriography were evaluated in 231 consecutive patients (age 58 +/- 10 years, 26% women) without prior myocardial infarction. 149 patients had coronary narrowing > 50%: 104 with multivessel disease and 45 with one vessel disease. Tomographic stress defect score was obtained by semiquantitative analysis (maximal score 65). Univariate and multivariate analysis was performed to identify discriminant parameters between one vessel and multivessel patients. RESULTS: The sensitivity and specificity for the identification of individual artery disease was 74% and 85% for left anterior descending artery, 79% and 85% for right coronary and 45% and 96% for circumflex artery. In the prediction of multivessel involvement the sensitivity was 65%, specificity 87%, positive predictive value 81% and negative predictive value 76%. In the bivariate analysis, four parameters differed significantly between one vessel and multivessel disease patients: ST downslope > 1 mm (p = 0.01), ST downslope/heart rate corrected (p = 0.005), reversible defects in two or more regions (p = 0.009) and SPET score (p = 0.002). In the multivariate analysis the probability of multivessel disease was 90% when ST depression > 1 mm and SPET score > 20 were associated and the probability was lowered to 16% when these criteria were not present. CONCLUSION: Myocardial SPET with MIBI offers an accurate localization of individual coronary artery disease, mainly in left anterior descending artery and right coronary artery lesions. Combined evaluation of ST depression and extension of myocardial stress defects improved prediction of multivessel involvement.     

Salutary effects of myocardial ischemia in coronary artery disease

A novel fine wire bone transport system for use with Ilizarov frames has been used in Bristol. It uses parallel wires instead of crossed wires. Its stiffness has been tested and compared with a crossed wire construct. In its basic form it is not as stiff to bending and shear loading, however, by modification it can be made at least as stiff. A parallel wire construct does not transfix as much soft tissue as a crossed wire construct when used in the leg. This is advantageous, because soft tissue transfixion causes pain and limb swelling, which impair patient mobilization.     

Identification of a hypoperfused segment in bull's-eye myocardial perfusion images using a feed forward neural network

Artificial neural networks are computer systems which can be trained to recognize similarities in patterns and which learn by example; one of the more straightforward types being the feed forward neural network (FFNN). We previously reported the use of FFNNs for classification of hypoperfusion patterns in bull's-eye representation of 201Tl single photon emission tomography myocardial perfusion studies and showed that, when such an image was divided into 24 segments, FFNNs could detect perfusion defects without direct comparison to a normal data base. This has been extended in this investigation to assess the ability of an FFNN, trained on data in which only a single segment was hypoperfused, to detect this abnormal segment when the hypoperfusion pattern of the other segments in the image varied. The results indicated that the network could reliably determine whether a segment was normally or under perfused, with accuracies of 99% and 100%, respectively, if all other segments were normally perfused. It could also reliably detect a normally perfused segment, even if other segments were hypoperfused, with accuracies of 95% and 98%. The network was less reliable, however, in detecting a hypoperfused segment when other segments were also hypoperfused, showing accuracies of only 74% and 88%.     

Tc-99m tetrofosmin myocardial perfusion SPECT after dipyridamole combined with low-level exercise in the diagnosis of coronary artery disease

Thymic lymphoma (TL) was observed in different stages of development in 46% of male mice (23/50) following exposure to an acute challenge dose of 2 Gy 60Co gamma-rays. With an adapting dose of 1 cGy 24 h prior to the challenge dose of 2 Gy, similar growth of TL was seen in 42.5% of mice (17/40). TL was not found in unirradiated control mice (0/50) or in the group treated with 1 cGy (0/50). Multiple adapting doses for 5 or 10 consecutive days induced TL in 8/50 and 9/50 mice, respectively (17% in average). When multiple adapting doses were followed by the challenge dose, the yield of TL was much lower, 16% (8/50) and 30% (15/50), respectively. By 15, 30, 60, 90, and 120 days after exposure with 3 Gy of 60Co gamma-rays, TL developed in 30, 70, 70, 80 and 85% of the female mice, respectively. When mice were conditioned with an adapting dose of 1 cGy 24 h prior to the challenge dose, TL was not found 15 days post-irradiation, while about a 25% reduction in the occurrence of TL was noticed at all other intervals. The results suggested that an adapting dose could play a role in bringing about a change in terms of delay and inhibition of the acute effects of radiation, i.e., the onset of TL in mice.     

Optimal criteria for the diagnosis of coronary artery disease by dobutamine stress echocardiography

Left ventricular remodeling occurs spontaneously among patients with hypertrophic cardiomyopathy in several ways: (1) wall thickening in children; (2) wall thinning associated with cavity enlargement in midlife; and possibly (3) a very gradual wall thinning process occurring over long periods of time in adulthood.     

Assessing myocardial perfusion in coronary artery disease with magnetic resonance first-pass imaging

MRFP perfusion imaging can now be used clinically on most MR scanner systems (1.0 to 1.5 T). The current experimental data demonstrate that MRFP imaging allows the quantitative assessment of myocardial blood flow changes and accurate measurements of collateral flow, including changes in the collateral dependent zones. Certain protocols, however, as outlined here have to be followed to obtain all the possible diagnostic information. Based on the current data on MRFP imaging, it is realistic to anticipate that MRFP imaging in combination with cine or tagging MR imaging will provide clinicians with better methods to distinguish stunned and hibernating, from nonviable myocardium and obtain better outcome data. Dedicated MR scanners are now being designed to meet the needs for MR imaging of patients with coronary artery disease. These scanners, small in size and with better patient access, make placement near the coronary care unit or catheterization laboratory feasible. This is a major step toward enhancing the utility of this new technique by providing the necessary infrastructure for scanning large numbers of patients. The main obstacle to wider use of these new diagnostic tools to assess perfusion is the lack of a large clinical database because there have not yet been major multicenter trials. With the development of novel intravascular contrast agents, however, larger trials are planned that should provide the clinical data mandatory for full integration of MRFP imaging into clinical practice. In particular, the development of dedicated and user-friendly perfusion analysis software will create the means to evaluate MR perfusion data accurately in large patient populations. These studies need to be conducted in a collaborative fashion by cardiologists, heart surgeons, and radiologists to be fully accepted by health care providers in an increasingly cost-averse and competitive health care environment.     

Insulin resistance in patients with a recent diagnosis of coronary artery disease

Insulin increases limb blood flow in a time- and dose-dependent manner. This effect can be blocked by inhibiting nitric oxide synthesis. These data raise the possibility that insulin resistance is associated with endothelial dysfunction. To examine whether endothelial function and insulin sensitivity are interrelated we quantitated in vivo insulin-stimulated rates of whole body and forearm glucose uptake at a physiological insulin concentration (euglycaemic hyperinsulinaemic clamp, 1 mU.kg-1.min-1 insulin infusion for 2 h) and on another occasion, in vivo endothelial function (blood flow response to intrabrachial infusions of sodium nitroprusside, acetylcholine, and N-monomethyl-L-arginine) in 30 normal male subjects. Subjects were divided into an insulin-resistant (IR) and an insulin-sensitive (IS) group based on the median rate of whole body glucose uptake (31 +/- 2 vs 48 +/- 1 mumol.kg-1.min-1, p < 0.001). The IR and IS groups were matched for age, but the IR group had a slightly higher body mass index, percentage of body fat and blood pressure compared to the IS group. The IR group also had diminished insulin-stimulated glucose extraction (p < 0.05) compared to the IS group, while basal and insulin-stimulated forearm blood flow rates were identical. There was no difference between the IR and IS groups in the forearm blood flow response to endothelium-dependent (acetylcholine and N-monomethyl-L-arginine) or -independent (sodium nitroprusside) vasoactive drugs. In conclusion, the ability of insulin to stimulate glucose uptake at physiological insulin concentrations and endothelium-dependent vasodilatation are distinct phenomena and do not necessarily coexist.     

Predictors of underlying coronary artery disease in cocaine associated myocardial infarction: a meta-analysis of case reports

A preliminary report presenting the results of fibular strut grafting in the severely resorbed mandibular and maxillary region is presented. Thirteen patients were treated due to severe resorption of alveolar and basilar bone of 49 segments of the mandible and the maxilla. Two patients additionally had pathological fractures of the mandible. In 10 cases the strut graft was harvested by means of a new minimally invasive technique. After modelling the fibular bone it was fixed to the recipient site by miniscrews or implants. After a mean follow-up period of 20 months (max. 31, min. 11 months) a retrospective analysis of clinical and radiological findings was carried out. It showed that a mean augmentation of 16 mm was achieved. Compared to other studies the fibular strut graft was resorbed less, and due to the primary stability it could be used for the treatment of fractures of the mandible. No more than natural resorption was observed when the patients received their prostheses fixed to dental implants.     

Low fat intake and coronary artery disease in a population with higher prevalence of coronary artery disease: the Indian paradox

OBJECTIVE: To determine the association between saturated fat intake and prevalence of coronary artery disease (CAD) and coronary risk factors. DESIGN AND SETTING: Total community cross sectional survey of 20 urban streets out of 196 streets, in the city of Moradabad in north India. SUBJECTS AND METHODS: Adult population between 25 to 64 years inclusive comprised of 1806 subjects (904 men, 902 women) were divided into three groups according to level of saturated fat intake as assessed by 7-day dietary intake records (very low < 7%, low 7 to 10%, high > 10% energy (en) per day). RESULTS: We examined the relationship between CAD risk and levels of % en from fat intake. Low (7 to 10% en/day) and high (> 10% en/day) saturated fat were positively and significantly associated with higher prevalence of CAD. The prevalence of coronary risk factors (hypertension, hypercholesterolemia, obesity and sedentary lifestyle) were significantly higher among subjects with low and high saturated fat intake compared to subjects with very low (< 7%) saturated fat intake. Logistic regression analysis with adjustment for age showed that hypercholesterolemia (OR: men 0.89, women 0.68), hypertension (men 0.92, women 0.56), physical activity (men 0.80, women 0.36), obesity (men 0.82, women 0.88) and smoking (0.70 men) were significant risk factors of CAD. Low and high saturated fat intake were associated with more prestigious occupations, higher and middle income status and better educational levels compared to very low saturated fat intake. CONCLUSIONS: The prevalence of CAD and coronary risk factors was higher in urban Indians with low and high saturated fat intake than those with lower saturated fat intake. These findings suggest that the saturated fat intake should be < 7% en/day for prevention of CAD in Indians.     

Stress technetium-99m tetrofosmin myocardial scintigraphy: a new one-hour protocol for the detection of coronary artery disease

The primary objective of this study was to evaluate in a random double-blind design, the sedative and behavioural responses of children undergoing outpatient paediatric dental procedures receiving either chloral hydrate (CH) alone or in combination with hydroxyzine. Forty American Society of Anaesthesiologists class I children (21 to 36 months of age) were randomly allocated to receive either 70 mg/kg CH alone or with 2 mg/kg hydroxyzine. The degree of crying, movement and overall behaviour was evaluated during treatment at different times. The combination of chloral hydrate/hydroxyzine (CH/H) significantly decreased crying and movement in relation to the effect induced by CH alone (p < 0.05) only at 45-60 min following the insertion of a rubber dam, whereas the overall behavior in both groups was no different throughout the dental procedures. In conclusion, our study demonstrated that hydroxyzine increased the effect of CH. However, because of the presence of high rates of oxygen desaturations and of deep sedation, careful use of this drug combination should be stressed.     

Effect of suture closure of coronary artery fistula on aneurysmal coronary artery and myocardial ischemia

This study indicates the importance of coronary angiography and myocardial scintigraphy on long-term follow-up of patients after surgery for coronary arterial fistula in view of the progression to coronary artery obstruction and myocardial ischemia.     

Fasting and nonfasting iodine-123-idophenylpentadecanoic acid myocardial SPECT imaging in coronary artery disease

Iodine-123-labeled idophenylpentadecanoic acid (IPPA) metabolic imaging has been shown to be clinically useful for the identification of myocardial viability in patients with coronary artery disease and left ventricular dysfunction. Imaging is usually performed under fasting conditions since nonfasting conditions may affect myocardial uptake of 123I-IPPA. The purpose of this study was to examine the impact of dietary condition on 123I-IPPA metabolic imaging. METHODS: Forty patients with stable coronary artery disease underwent, in randomized order and on separate days, 123I-IPPA SPECT myocardial imaging under fasting and nonfasting conditions. Patients were injected with 123I-IPPA (4-5 mCi) at rest with imaging performed at 4 (initial) and 30 (delay) min. For each image (initial and delay images), 10 segments were analyzed by three experienced observers without knowledge of patient identity or dietary condition using a 5-point grading system (O = no uptake to 4 = normal uptake). A summed global score was obtained for each image by adding the scores for all 10 segments. Image quality was assessed using a 3-point grading system. RESULTS: Visual agreement for normal and abnormal segments between fasting and nonfasting conditions was 82% (kappa = 0.63). There were no significant differences in the summed global scores for both conditions. Image quality was equivalent for both conditions in 65% of cases and superior under the nonfasting condition in 25% of cases. CONCLUSION: Image quality as well as the presence, location and severity of defects are similar under fasting and nonfasting conditions with 123I-IPPA. Therefore, fasting is not necessary before 123I-IPPA SPECT imaging for the assessment of myocardial viability.