Automatic detection of left ventricular contours from cardiac cine magnetic resonance imaging using fuzzy logic

RATIONALE AND OBJECTIVES

Gated cardiac cine magnetic resonance imaging provides accurate dynamic data of the left ventricular function. However, the manual extraction of important physiologic parameters such as myocardium wall thickness and left ventricular volumes is invariably time consuming and subjective. To reduce the variability and time constraints inherent in observer contour tracing, the authors developed an automatic left ventricle contour-detection method.

METHODS

The purpose was to apply fuzzy logic-based automatic contour detection to identification of endocardial and epicardial borders in short-axis magnetic resonance images. The automatic contouring was compared with manual tracing using the calculated ejection fraction as the comparison criterion.

RESULTS

A good correlation was found between the two approaches (r2 = 0.98).

CONCLUSIONS

The ejection fraction can be obtained using this automatic contouring method.

Nuclear magnetic resonance evidence of different muscular adaptations after resistance training

OBJECTIVE

To evaluate muscle bioenergetics, muscle cross-sectional area (CSA), and soreness when the gastrocnemius was subjected to concentric and concentric/eccentric resistance training modes.

DESIGN

Prospective study, before and after training. The subjects served as their own controls.

SETTING

Rehabilitation center and nuclear magnetic resonance spectroscopy unit of a university hospital.

PARTICIPANTS

Sixteen healthy young volunteers from the local physiotherapist school.

INTERVENTION

Two distinct resistive training programs were evaluated on the gastrocnemius: a protocol consisting of concentric contractions only and a mixed concentric/eccentric program.

MAIN OUTCOME MEASURES

Maximal isometric resistance was measured after each training session. Before and after training, muscle CSA was appreciated using magnetic resonance imaging, whereas changes in muscle pH, phosphorus metabolite ratios, maximal oxidative power (Pmax), and oxidative phosphorylation were studied using 31P nuclear magnetic resonance spectroscopy at rest and during an incremental exercise protocol.

RESULTS

Magnetic resonance imaging revealed a significant increase (7.1%) in the gastrocnemius CSA in the concentric-eccentric group only. The PCr/Pi (8.3 +/- 0.9 vs 10.4 +/- 1.7) and PCr/ATP (3.68 +/- .36 vs 4.07 +/- .27) resting ratios increased significantly (p = .008) after concentric-eccentric resistance training. Pmax was significantly improved in the concentric-eccentric group (7.0 +/- 2.1W vs 8.4 +/- 1.8W: p < .02). This mixed protocol also reduced the incidence of muscular soreness.

CONCLUSION

The data suggest that the improved oxidative mechanical power output could be due mainly to a greater muscle cross-section in the concentric-eccentric group, with circumstantial evidence suggesting a relatively higher type IIa fiber activity.

[Dermoid cyst of the ovary. False positive diagnosis in iodine 131 scintigraphy of differentiated thyroid cancers]

BACKGROUND

Total body 131-iodine labeled scintiscan is used to screen for residual tumoral tissue after ablation of differentiated thyroid carcinoma. At therapeutic doses, radioactive iodine can also be used for treatment. Thyroglobulin level, usually undetectable a few months after total thyroidectomy and metabolic irradiation with 131-iodine in patients without initial metastases, is absolutely necessary for interpreting the scintiscans. Iodine uptake occur in dermoid cysts which usually contain thyroid tissue.

CASE REPORT

A 44-year old woman underwent total thyroidectomy with node dissection for papillary carcinoma of the thyroid with a vesicular architecture. Four months later, the total body 131-iodine scintiscan demonstrated a round zone of uptake in the pelvic area. The lesion was found to be a typical dermoid cyst. No thyroid or tumoral tissue could be demonstrated.

DISCUSSION

Dermoid cysts can be the cause of false positive 131-scintiscans in patients followed after resection of differentiated thyroid carcinoma. Unlike previously reported cases, the dermoid cyst in this patient was totally devoid of thyroid tissue.

[False positive scintigraphic images in the surveillance of differentiated thyroid cancers]

Iodine-131 whole body imaging and serum thyroglobulin are used in the follow-up evaluation of differentiated thyroid carcinomas. Iodine 131 is used to detect and treat functioning lesions. Iodine 131 activity detected outside the normal thyroid bed is usually attributed to metastatic disease. False-positive localization of radioiodine has been described, and may be a potential pitfall. We report here six personal cases of false-positive localisations of radioiodine du to body secretions, pathologic exudate, activity in nonlactating breast, salivary gland inflammation, ovarian teratoma. Some of these false-positive can be ruled out easily by removing of clothes, removing of nozzle in patients with tracheostomy, or by ingestion of water in subjects with abnormal mediastinal hyperfixation. Recognition of false-positive radioiodine images is very important to prevent costly additional investigation and possibly inappropriate therapy.

Effects of low-frequency electrical stimulation of quadriceps and calf muscles in patients with chronic heart failure

PURPOSE

The aim of this preliminary study was to evaluate the effects of low-frequency electrical stimulation of quadriceps and calf muscles on global exercise capacities, skeletal muscle metabolism, calf muscle volume, and cardiac output in patients with chronic heart failure.

METHODS

Fourteen patients with chronic heart failure (mean age of 56.4 years +/- 9.1 SD; mean radionuclide left ventricular ejection fraction of 22.3% +/- 8.8 SD) underwent 5 weeks (1 hour per day, 5 days per week) of low-frequency electrical stimulation of quadriceps and calf muscles.

RESULTS

Low-frequency electrical stimulation was well tolerated. Exercise capacity and the calf muscles volumes increased significantly after rehabilitation in comparison with prior rehabilitation (the peak oxygen consumption increased from 17.2 mL/(kgmin) +/- 5.3 SD to 19.6 mL/(kgmin) +/- 5.9 SD; the anaerobic threshold increased from 12.3 mL/(kgmin) +/- 3.2 SD to 15.2 mL/(kgmin) +/- 3.3 SD; the 6-minute walking test increased from 419 m +/- 122 SD to 459 m +/- 114.3 SD; the gastrocnemius volume increased from 259.4 cm3 +/- 58 SD to 273.4 cm3 +/- 74 SD, and the soleus volume increased from 319 cm3 +/- 42.9 SD to 338 cm3 +/- 52.5 SD). The New York Heart Association class was improved after rehabilitation. The P-31 nuclear magnetic resonance spectroscopy of gastrocnemius muscle data were not significantly modified after rehabilitation, thereby inferring that no significant improvement of the muscle metabolism occurred. These data reinforce the hypothesis of an increased muscle mass during stimulation. It is noteworthy that the electrical stimulation did not increase cardiac output at any stage; an enormous asset in favor of this mode of rehabilitation.

CONCLUSION

These results suggest that low-frequency muscular electrical stimulation is well tolerated, induces an increased exercise capacity in patients with chronic heart failure, without an undesirable increase in cardiac output.

Muscle metabolism changes with training in the nonamputated limb after vascular amputation: interest of phosphorus 31 NMR spectroscopy

OBJECTIVE

To determine by 31P nuclear magnetic resonance (NMR) spectroscopy the efficacy of training in improving aerobic metabolism of calf muscle in nonamputated limb after recent vascular amputation; to assess the possible associated microcirculatory changes; and to evaluate the need for noninvasive monitoring techniques during training in the nonamputated limb after recent vascular amputation.

DESIGN

Prospective study, before and after training. Subjects served as their own controls and were compared with a control group.

SETTING

Rehabilitation center of a university hospital.

PATIENTS

Ten unilateral vascular amputated patients were included with ankle systolic index between 0.5 and 0.8 in the nonamputated limb, and 10 control subjects without cardiovascular disease or risk factors of atherosclerosis with ankle systolic index of >.95.

INTERVENTION

Walking with prosthesis at self-selected velocity over increasing walking distance, arm training at a workload of 60% of a maximal arm test, and analytical exercises of the nonamputated leg (dynamic contractions against low resistance). Subjects received training as inpatients, 5 days a week.

MAIN OUTCOME MEASURES

Before and after training, ankle systolic index, forefoot transcutaneous oxygen tension (TcPO2) and veno-arteriolar reflex, and digital plethysmography of the second toe with reactive hyperemia test were studied. Changes in calf muscle pH, phosphocreatine (PCr), and inorganic phosphate (Pi) were measured by 31P NMR spectroscopy at rest and during a plantar flexion-type incremental protocol.

RESULTS

There was no significant difference in ankle systolic index (.63 +/- .10 vs .64 + .07) or in TcPO2 (42 +/- 11 vs 44 +/- 10mmHg), and there was reappearance of veno-arteriolar reflex in 3 cases, of a plethysmographic signal in 2 cases, and of the positivity of the reactive hyperemia test in 3 cases. No differences were found with 31P NMR spectroscopy at rest before and after training. At the same workload (1 watt) the difference of the ratio (PCr/(PCr + Pi)) of rest to effort (PCr depletion) was significantly increased in the amputated patients (.423 +/- .159 vs .145 +/- .058; p < .01). This difference of ratio was lower after training (.360 +/- .158 vs .423 +/- .159; p < .05). The pH was less acid between the two periods.

CONCLUSION

Vascular monitoring with systolic index and TcPO2 is necessary to follow and to prevent serious ischemia of the nonamputated limb. Claudication is often not detected because of early exhaustion during walking. Training after recent vascular amputation improves the skeletal muscle oxidative capacity.

[Study of myocardial viability after myocardial infarction. Value and limits of magnetic resonance imaging compared with myocardial scintigraphy]

The aim of this study was to compare myocardial thickness measured by magnetic resonance imaging and quantified fixation of thallium. Twenty-one patients 61.2 +/- 11 years were investigated after myocardial infarction of the anterior wall in 8 cases, inferior in 10 cases, lateral in 2 cases and apical in one case. The mean angiographic ejection fraction was 46.5 +/- 19%. Myocardial scintigraphy was performed after an exercise or pharmacological stress test and followed by a study of redistribution. The data was analysed by a quantitative method. Magnetic resonance imaging was performed with vertical and horizontal long axis views in systole and diastole with division of the left ventricle into the same 12 regions. Three groups were defined according to fixation during redistribution. Group I: regions with fixation > 80% (n = 155); group II: 60 to 80% (n = 78); group III: fixation < 60% (n = 19). All measurement of myocardial thickness were correlated (p < 0.01) with the fixation of thallium during redistribution. Systolic thickening, was significantly greater in group I (3.80 +/- 3.1 mm) than in groups II (2.20 +/- 3.8 mm) and III (1.56 +/- 2.4 mm) in which it was comparable. Regions in group III had systolic (8.61 +/- 3.53) and diastolic (6.89 +/- 3.3 mm) thicknesses significantly inferior to those in groups I (13.79 +/- 4.4 mm: 9.95 +/- 2.8 mm) and II (11.59 +/- 5.5 mm: 9.38 +/- 2.9 mm). Ninety per cent of regions with a systolic thickness of over 10 mm had fixation during redistribution of more than 60%. This study shows that myocardial thickness is correlated to scintigraphic data. The systolic thickness over 10 mm would confirm the viability of a given region.

Bone scintigraphy equipped with a pinhole collimator for diagnosis of avascular necrosis of the femoral head

The objective was to compare the sensitivities for diagnosis of avascular necrosis of the femoral head of bone scintigraphy equipped with a pinhole collimator and with an high resolution parallel collimator. Bone scintigraphy equipped with a pinhole collimator and with an high resolution parallel collimator were performed in 16 patients with bilateral (n=7) or unilateral (n=9) avascular necrosis of the femoral head. Bone scintigraphy equipped with a pinhole collimator documented a photopenic defect in 78.3% of the necrotic hips, while bone scintigraphy equipped with an high resolution parallel collimator documented a defect in 47.8%. There was no false-positive diagnosis of avascular necrosis of the femoral head on either bone scintigraphy equipped with a pinhole or with an high resolution parallel collimator. In conclusion, bone scintigraphy equipped with a pinhole collimator has a greater sensitivity for diagnosis of avascular necrosis of the femoral head than bone scintigraphy equipped with an high resolution parallel collimator.

Severe right ventricular contraction asynchronism revealing a large pericardial effusion

A gated blood-pool equilibrium radionuclide angiography was performed in a patient to determine the ejection fraction for doxorubicin cardiotoxicity evaluation. The phase image of the first harmonic of the Fourier analysis revealed a severe delay of the right ventricular contraction compared with that of the left ventricle. This right ventricular contraction asynchronism was due to a large pericardial effusion, confirmed by the presence of the halo sign on the summed gated images and by echocardiography. The phase delay moves towards normalization after pericardiocentesis. Although radionuclide angiocardiography is not the best method for identification of pericardial effusion, this diagnosis should be evoked when a severe homogenous delay of the right ventricular contraction is observed.

Automatic detection of cardiac contours on MR images using fuzzy logic and dynamic programming

This paper deals with the use of fuzzy logic and dynamic programming in the detection of cardiac contours in MR Images. The definition of two parameters for each pixel allows the construction of the fuzzy set of the cardiac contour points. The first parameter takes into account the grey level, and the second the presence of an edge. A corresponding fuzzy matrix is derived from the initial image. Finally, a dynamic programming with graph searching is performed on this fuzzy matrix. The method has been tested on several MR images and the results of the contouring were validated by an expert in the domain. This preliminary work clearly demonstrates the interest of this method, although a formal evaluation has to be done.

Abnormalities in exercising skeletal muscle in congestive heart failure can be explained in terms of decreased mitochondrial ATP synthesis, reduced metabolic efficiency, and increased glycogenolysis

OBJECTIVE

To distinguish between the effects of reduced oxidative capacity and reduced metabolic efficiency on skeletal muscle bioenergetics during exercise in patients with congestive heart failure.

DESIGN AND PATIENTS

Patients were studied by 31P magnetic resonance spectroscopy during aerobic exercise and recovery, and results compared with controls.

RESULTS

In flexor digitorum superficialis muscle (26 patients) there was a 30% decrease in oxidative capacity compared with control (mean (SE) 36 (2) v 51 (4) mM/min) and also a 40% decrease in "effective muscle mass" (5 (1) v 9 (1) arbitrary units), probably at least partly the result of reduced metabolic efficiency. Both contribute to increased phosphocreatine depletion and intracellular acidosis during exercise. However, an increased concentration of ADP (an important mitochondrial regulator) during exercise permitted near-normal rates of oxidative ATP synthesis. Results were similar in gastrocnemius muscle (20 patients), with a 30% decrease in maximum oxidative capacity (29 (4) v 39 (3) mM/min) and a 65% decrease in effective muscle mass (5 (1) v 13 (2) arbitrary units). Exercise training improved maximum oxidative capacity in both muscles, and in gastrocnemius effective muscle mass also.

CONCLUSIONS

Skeletal muscle exercise abnormalities in patients with congestive heart failure results more from decreased metabolic efficiency than from the abnormalities in mitochondrial oxidation. Both decreased efficiency and defective mitochondrial oxidation result in an increased activation of glycogen phosphorylase, and may be improved by exercise training.

Reduced brain N-acetyl-aspartate in frontal lobes suggests neuronal loss in patients with amyotrophic lateral sclerosis

We performed proton magnetic resonance spectroscopy (1H-MRS) in three patients with amyotrophic lateral sclerosis (ALS) to evaluate the distribution and extent of cortical neuronal damage as demonstrated by decreased N-acetyl-aspartate (NAA) levels. We examined primary motor (precentral gyrus) and parietal neocortical (superior parietal gyrus) regions. ALS was defined with lower and upper motor neuron signs. Compared with matched healthy controls, ALS patients had a significant decrease in NAA levels in the primary motor cortex (p < 0.001) compared with parietal regions and homologous regions in healthy controls. Two clinical applications can be extracted: first, the upper motor neuron signs present in the ALS, come from a neuronal loss within the primary motor cortex and may explain the frontal syndrome associated with ALS. Second clinical applications of 1H-MRS could include identification of extent of upper motor neuron involvement, aiding diagnosis of syndromes presenting with an ALS-like syndrome.

Relationship between increased peak oxygen uptake and modifications in skeletal muscle metabolism following rehabilitation after myocardial infarction

PURPOSE

Rehabilitation after myocardial infarction produces an increased peak oxygen uptake (VO2peak). This study investigates the relationship between the modifications in skeletal muscle metabolism and the modification in VO2peak induced by a standard program of physical training following a myocardial infarction.

METHODS

Seventeen patients (14 male, 3 female) were studied by phosphorus 31(31P) magnetic resonance spectroscopy after the acute phase of a myocardial infarction and after 2 months of rehabilitation. Changes in calf muscle pH, phosphocreatine, and inorganic phosphates were measured at rest and during a plantar flexion-type incremental workload protocol. Calf muscle pH, phosphocreatine/(phosphocreatine + inorganic phosphates), and inorganic phosphates/phosphocreatine ratios were compared at the highest identical workload attained in both studies. The VO2peak (mL/kg/min) was determined during a cycle stress test.

RESULTS

At the highest identical workload attained in both tests, the ratio phosphocreatine/(phosphocreatine + inorganic phosphates) was significantly higher (0.48 +/- 0.15 to 0.57 +/- 0.18: P < .001), and the ratio inorganic phosphates/phosphocreatine was lower (1.38 +/- 1.14 to 0.99 +/- 0.87: P < .01). After rehabilitation, no difference was observed for the pH at stress (6.83 +/- 0.16 to 6.91 +/- 0.14: not significant [NS]). The increase in the VO2peak was significant after rehabilitation (24 +/- 9 to 29 +/- 11 mL/kg/min: P < .001). The VO2peak improvement induced by the physical training was correlated with the increase in the phosphocreatine/(phosphocreatine + inorganic phosphates) (r = 0.818, P < .001).

CONCLUSIONS

The reduction in phosphocreatine depletion indicated that the oxidative capacity of the skeletal muscle was improved during the rehabilitation. The good correlation between the indexes of skeletal muscle metabolism and VO2peak suggests the peripheral effect of training.

Diastolic or systolic left and right ventricular impairment at moderate doses of anthracycline? A 1-year follow-up study of women

A prospective study was carried out to assess the early and later alterations in left and right ventricular diastolic and systolic function after the termination of anthracycline therapy. In 33 women without cardiac disease who were treated by anthracycline therapy, cardiac function was evaluated by radionuclide angiography before the treatment (T0) and 1 month (T1) and 12 months (T12) after the end of the treatment. Cardiac function was assessed by radionuclide measurement throughout treatment. Analysis of ejection fraction (EF), peak ejection rate (PER), time to PER (TPER), peak filling rate (PFR) and time to PFR (TPFR) was performed before and after treatment. To normalise radionuclide measurements of the ventricular diastolic function, the ratio of the PFR and the EF and the ratio of the PFR and the PER were calculated. No patient developed symptomatic congestive cardiac failure. One-way analysis of variance showed a significant decrease in the three parameters (EF, PER, PFR) over time only for the left ventricle (LV); no significant alterations appeared for the right ventricle (RV). The EF of the LV decreased from 59%+/-5% at T0 to 57%+/-6% at T1 and 56%+/-5% at T12. The PER of the LV fell from 3.03+/-0.40 end-diastolic volume per second (EDV/s) at T0 to 2.79+/-0.47 at T1 and 2.78+/-0.43 at T12. The PFR of the LV dropped from 2.99+/-0.43 EDV/s at T0 to 2.62+/-0.44 at T1 and 2.56+/-0.42 at T12. For the normalised ratios, no differences were observed. Significant differences were found for EF, PER and PFR between T0 and T1, and between T0 and T12, but no difference was found between T1 and T12. This report shows simultaneous impairment of the systolic and diastolic LV radionuclide parameters at 1 and 12 months after anthracycline therapy without alteration in the RV function.

Asymmetric metabolic profile in mesial temporal lobes: localized H-1 MR spectroscopy in healthy right-handed and non-right-handed subjects

PURPOSE

To determine a possible asymmetric metabolic profile in right- handed and non-right-handed healthy subjects by comparing proton spectra from temporal lobes.

MATERIALS AND METHODS

Twenty-eight healthy adults (17 right-handers, 11 non-right-handers) underwent magnetic resonance (MR) imaging and single-voxel MR spectroscopy. N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) peak areas were measured.

RESULTS

Volume of hippocampal formations was larger on the right in right-handers (right volume: 4.04 cm3 +/- 0.67 vs left volume: 3.84 cm3 +/- 0.62; P = .00004) and in non-right-handers (right volume: 4.22 cm3 +/- 0.78 vs left volume: 4.05 cm3 +/- 0.80; P = .004). NAA/Cho was significantly higher in the left temporal lobe of right-handers (right lobe: 1.53 +/- 0.18 vs left lobe: 1.89 +/- 0.18; P=.00004) as was NAA/Cr (right lobe: 1.79 +/- 0.36 vs left lobe: 2.45 +/- 0.45; P=.0001). No statistically significant difference was noted for these ratios in non-right-handers: NAA/Cho (right lobe: 1.49 +/- 0.18 vs left lobe: 1.61 +/- 0.35) and NAA/Cr (right lobe: 1.93 +/- 0.45 vs left lobe: 2.40 +/- 0.70).

CONCLUSION

A clear metabolic asymmetry observed in right-handers is less clear-cut in non-right-handers. Both tendencies should be considered when assessing the brain metabolism of patients with uni- or bilateral disorders, such as temporal lobe epilepsy.

Quantitative myocardial thallium single-photon emission computed tomography in normal women: demonstration of age-related differences

The aim of this study is the development of a database of normal women for quantitative analysis of exercise and reinjection myocardial single-photon emission computed tomography (SPET). We studied 101 subjects (40 males and 61 females) with less than 5% likelihood of coronary artery disease. All patients underwent stress and rest thallium-201 myocardial SPET. Myocardial stress was induced by bicycle exercise test (n=51), dipyridamole infusion (n=27) or a combined test (n=23). Multivariate ANOVA showed that the type of stress did not influence the percentage of thallium uptake for each region. Significant differences between men and women were found for the percentage of uptake in the inferior and the anterior wall. The most original finding of this study is the correlation between age and thallium uptake in the three regions of the anterior wall, showing an increase in measured thallium uptake with age for women. Consequently, two groups of women, those under and those over 55 years old, were separated, with a significantly lower tracer uptake in the anterior wall in the younger age group. These results may suggest that the commonly described breast tissue attenuation is due not only to breast volume or morphology but also to breast density. This emphasizes the need for two different databases for myocardial SPET quantitative analysis in the female population. Awareness of this fact should allow avoidance of any underestimation of possible anterior wall ischaemia in women aged more than 55 years.

Myocardial effects of experimental acute brain death: evaluation by hemodynamic and biological studies

BACKGROUND

Because of problems concerning the functional quality of heart transplants, more and more interest has been focused on the physiologic changes occurring during brain death, one of the major possible contributing factors to the myocardial alterations.

METHODS

The aim of this study was to describe the link between acute experimental brain death and myocardial metabolism. This was achieved by in vivo 3-hour hemodynamic and biological (myocardial lactate production) studies and then in vitro 6-hour phosphorus-31 nuclear magnetic resonance spectroscopy. Two groups of pigs were involved in the study: group I (n = 10) as control and group II (n = 10) as brain-dead animals.

RESULTS

Within the first hour, we observed a strong increase in myocardial activity associated with the onset of myocardial lactate production, lasting 2 hours and corresponding to a myocardial anaerobic metabolism period. Despite the apparent normalization before excision of the hearts, phosphorus-31 nuclear magnetic resonance spectroscopy revealed a significant decrease in adenosine triphosphate levels in group II when compared with group I.

CONCLUSIONS

We conclude that, in our study, acute experimental brain death is associated with an early and transient period of myocardial anaerobic metabolism and adenosine triphosphate consumption. These myocardial consequences of brain death could partially explain some observations of heart graft dysfunction.

Rat skeletal muscle metabolism in experimental heart failure: effects of physical training

Skeletal muscle metabolic abnormalities exist in chronic heart failure. The influence of physical training on muscle metabolism after myocardial infarction was studied in a rat model. 31P magnetic resonance spectroscopy and enzyme assays were performed in Wistar rats 12 weeks after coronary artery ligation. Infarcted rats were allocated randomly to either 6 weeks of training or non-training. Spectra were collected from the calf muscles during sciatic nerve stimulation at 2 Hz. Fibre typing and enzymatic assays were performed on the muscles of the contralateral non stimulated leg. Post-mortem rats were also divided into severe and moderate heart failure according to the lung weight per body weight. At 200 g twitch tension, phosphocreatine and pH were found to be significantly lower in the non-trained severe heart failure group compared with the other groups. Phosphocreatine recovery half-time was significantly longer in the non-trained group with severe heart failure and correlated with the citrate synthase activity in the muscle. The training did not induce a change in the enzyme activities in the infarcted animals with moderate heart failure but did correct the lower citrate synthase activity in the non-trained severe heart failure animals. This normalization of muscle metabolism was achieved by training without any change in calf muscle mass, making atrophy unlikely to be the sole cause of the metabolic changes in heart failure. Training in rats with severe heart failure can reverse the abnormalities of skeletal muscle metabolism, implicating decreased physical activity in the aetiology of these changes.

Myocardial perfusion imaging with technetium-99m-Tc NOET: comparison with thallium-201 and coronary angiography

We compared TcN-NOET [bis(N-ethoxy, N-ethyl dithiocarbamato)nitrido 99mTc] and 201Tl images to estimate the utility of this compound in the detection of coronary artery disease (CAD).

METHODS

Twenty-five patients undergoing cardiac catheterization had stress-redistribution-reinjection 201Tl SPECT imaging, stress-delayed (2, 4 and 6 hr postinjection) and rest-delayed (4 hr postinjection) TcN-NOET SPECT imaging.

RESULTS

Nineteen patients had coronary stenosis > or = 50% and six were normal. Stress TcN-NOET and 201Tl imaging were concordant for the presence of CAD in 22/25 patients (88%, kappa = 0.76 +/- 0.20). The overall sensitivity of TcN-NOET SPECT imaging was 74% (14/19 patients) and 68% (13/19 patients) for 201Tl SPECT imaging. The specificity was 100% (6/6 patients) for both techniques. The overall agreement of TcN-NOET and 201Tl for the presence of disease in individual coronary arteries was 96% (72/75 arteries, kappa = 0.92 +/- 0.16). Segmental analysis of stress images showed a concordance in 211/225 segments (94%, kappa = 0.82 +/- 0.09). Comparison of the 4-hr images showed a concordance between 201Tl and TcN-NOET in 21/23 patients. Following TcN-NOET injection at rest, seven patients had a defect on the initial images, which had normalized 4 hr postinjection in four patients (57%).

CONCLUSION

Perfusion imaging with TcN-NOET and 201Tl gives comparable diagnostic information in patients undergoing exercise testing for assessment of CAD. Because of the normalization of myocardial activity 4 hr after injection in some patients, we conclude that TcN-NOET is a potential technetium compound equivalent to 201Tl.

[N-acetyl-aspartate abnormalities in internal-temporal epileptic foci using proton magnetic resonance spectroscopy]

The aim of this study was to characterize the neurochemical abnormalities related to N-acetyl-aspartate which is a neuronal marker, within an epilepticus focus located in the internal-temporal area, using proton magnetic resonance spectroscopy. Eleven patients with a mono-hippocampal epileptics focus on clinical and per-critical electroencephalographical criteria, were matched with 11 controls by age, sex and laterality. Proton spectroscopy of a volume of 8 cm3 was performed within the ipsilateral and the contralateral internal-temporal area and within the 2 hippocampus of controls. Volumetry of the ipsilateral and the contralateral hippocampus and of the 2 hippocampus of controls was performed using resonance magnetic imaging. All these measurements were performed during the interictal stage. The results were concordant to show a decrease of the ratio N-acetyl-aspartate/choline and N-acetyl-aspartate/creatine within the epilepticus focus, in relation with a hippocampal atrophy. This study finds similar results to those of other previous works. The decrease of N-acetyl-aspartate levels within the epilepticus focus could be related to a decrease of the neuronal cell density. This procedure is able to show a decrease of the levels of this metabolite within an internal temporal epilepticus focus and associated with a hippocampal atrophy.

Magnetic resonance relaxation times in ventricular hypertrophy induced by myocardial infarction in the rat

The purpose of this study was to evaluate changes in the proton nuclear magnetic resonance relaxation times (T1 and T2) after chronic infarction in the rat. Ligation of the left coronary artery was followed by various degrees of reduction in myocardial blood flow. The ligation induced infarction in the left ventricle and compensatory hypertrophy in the right ventricle, as evaluated by the ratio of right ventricle to body weight. The interventricular septum and the right ventricle did not become ischemic in this model and served as control areas. In the infarcted left ventricle our results showed an increase in the T1 and T2 relaxation times after 15 and 30 days of ligation and a slight decrease after 60 days. A similar change in the T1 values was observed in the right ventricle. In contrast, a persistent increase in the T2 relaxation times was observed in the right ventricle and correlated with the ratio of right ventricle to body weight (r = 0.54, p < 0.01). The observation that the magnetic resonance relaxation times in vitro are modified in the hypertrophic right ventricle after myocardial infarction could be important in interpreting magnetic resonance imaging in vivo. There was no relation between the changes in the relaxation times and the degree of myocardial ischemia.