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PubMed1985

Asynchronous left ventricular regional function and impaired global diastolic filling in patients with coronary artery disease: reversal after coronary angioplasty.

Left ventricular diastolic filling is impaired in many patients with coronary artery disease and normal left ventricular systolic function, and is improved in many patients after coronary angioplasty (PTCA). To investigate the mechanisms for this improvement, we studied regional asynchrony by radionuclide angiography in 26 patients with single-vessel coronary artery disease before and after successful PTCA. Before PTCA, all patients had normal ejection fractions at rest and normal qualitative left ventricular regional wall motion, as determined by radionuclide and contrast angiography. Quantitative left ventricular regional function was assessed by dividing the left ventricular region of interest into 20 sectors. Phase analysis was performed on each sector's time-activity curve, and the average intersector phase difference was used as an index of left ventricular regional synchrony. Before PTCA, average intersector phase difference was increased compared with normal (6.0 +/- 2.2 vs 4.0 +/- 1.7 degrees, p less than .005), indicating asynchronous regional function. After PTCA, ejection fraction at rest was unchanged, but peak left ventricular filling rate at rest increased from 2.5 +/- 0.6 to 3.0 +/- 0.6 end-diastolic volume/sec (p less than .001) and was associated with a decrease in average intersector phase difference from 6.0 +/- 2.2 to 5.1 +/- 2.3 degrees (p less than .05). Average intersector phase difference decreased in 16 of 21 patients in whom peak filling rate increased after PTCA (p less than .005), compared with one of five patients in whom peak filling rate was unchanged or decreased. Hence, improved global left ventricular filling after PTCA was associated with more synchronous left ventricular regional behavior. To identify the cause of regional asynchrony before PTCA, we then generated time-activity curves from each of four left ventricular quadrants. These data indicated that the asynchrony was caused by regional variation in timing of diastolic rather than systolic events and that PTCA resulted in reduction in regional diastolic asynchrony. These data suggest that in many patients with coronary artery disease and normal left ventricular systolic function, impaired global diastolic filling may result from asynchronous left ventricular regional diastolic function, which is a reversible manifestation of myocardial ischemia or reduced coronary flow.

Adult↗
PubMed1983

Early behaviour of 99mTc-pertechnetate in the head after intravenous bolus injection: its relevance to the cerebral blood circulation.

The relative differences between the behavior of 99mTc-pertechnetate (Tc) and both, non-diffusible and diffusible reference tracers in the head were evaluated by a statistical comparison of their time-activity curves in blood, brain and some tissues underlying the brain, after IV injection in the rat. This study showed that the particular cephalic behaviour of Tc was neither similar to that of diffusible tracers (even with restricted diffusion) nor equivalent to that of a non-diffusible tracer in the whole head. Although Tc is not an intravascular tracer in the entire cephalic volume, it was demonstrated that the initial peak characterizing the dilution of this tracer in the head is exclusively generated by its first passage in the cerebral circulation, even if the blood flow rate is changed. To extract from this initial peak a first dilution curve relevant to the cerebral circulation, Tc kinetics in the head were considered as a two compartmental model. Assuming that the maximum uptake of tracer was reached at the same time in both compartments of this model, the disappearance of Tc from the fast compartment approximates the first dilution curve of Tc in the fast cerebral circulation, if the slope of the Tc disappearance curve from the slow compartment is assimilated to a plateau.

Animals↗
PubMed2004

Epilepsy.

PURPOSE OF REVIEW: The purpose of this review is to consider the current and potential role of neuroimaging from an epilepsy perspective, and to illustrate that by combining appropriate imaging techniques, neuroimaging can contribute greatly to elucidating the basic mechanisms of the various forms of epileptic disorders. RECENT FINDINGS: New magnetic resonance imaging sequences (magnetization transfer imaging) and positron emission tomography ligands (serotonergic system) were biologically validated in large groups of patients with localization-related epilepsies. Investigations in genetically determined homogenous patient populations (PAX6, juvenile myoclonic epilepsy) have strengthened the link between genetic defects and neuropathological targets (anterior commissure, thalamus). Magnetic resonance spectroscopy and electroencephalogram-triggered functional magnetic resonance imaging provided converging evidence for a key role of the thalamus in the generation of generalized seizures. The role of functional magnetic resonance imaging in identifying eloquent areas of cortex and its relationship to structural lesions, in particular malformations of cortical development, has been further elucidated. Longitudinal magnetic resonance imaging studies reported progressive volume loss after febrile convulsions and in active epilepsy. SUMMARY: Neuroimaging is essential for improving the efficacy and safety of therapeutic, in particular, surgical procedures. Investigations of larger, more homogenous genetic disorders and longitudinal rather than cross-sectional neuroimaging studies have advanced our knowledge about the cause and effect of epileptic disorders, and will ultimately link defects in molecular genetics with specific neuropathological targets.

Brain↗
PubMed1992

An instant kit method for labeling antimyosin Fab' with technetium-99m: evaluation in an experimental myocardial infarct model.

An instant kit method for labeling antibody Fab' fragments was developed. The method utilizes a ligand exchange reaction between the intermediate complex 99mTc-D-glucarate and the free sulfhydryl groups on the antibody Fab' fragment. Radiolabeling of the Fab' using generator eluate achieves quantitative 99mTc incorporation in less than 30 min at room temperature. The radiolabel is stable in human plasma for at least 24 hr and stable to incubation with 10 mM diethylene-triaminepentaacetic acid (24 hr) and 1 mM diaminodithiol agent (up to 3 hr). Mouse biodistribution of 99mTc-antimyosin shows faster blood clearance and lower uptake in the lungs, liver, and spleen in comparison to 111In-antimyosin. Technetium-99m-antimyosin and 111In-antimyosin showed equivalent ability to detect myocardial infarct in a canine model.

Animals↗
PubMed1981

Real-time inferior vena caval ultrasonography: normal and abnormal findings and its use in assessing right-heart function.

We studied the inferior vena cava (IVC) as an index of right-heart function in 111 patients. A two-dimensional echocardiographic sector was used to visualize the IVC, and its M-mode cursor was used to generate a time-motion record of the IVC size and pulsation. Normal subjects had a small presystolic A wave (less than 125% of the end-diastolic IVC dimension), a small systolic V wave (less than 140% of the end-diastolic IVC dimension), and a 50% inspiratory decrease in IVC dimension. The A wave was absent in patients with atrial fibrillation. When normalized for body surface area, mean end-diastolic IVC dimension correlated with mean right atrial pressure (r = 0.72, p less than 0.001). An A wave greater than or equal to 125% of end-diastolic IVC dimension was recorded in 71% of patients with sinus rhythm and an elevated right ventricular end-diastolic pressure of 10 mm Hg or greater, but in no patient with right ventricular end-diastolic pressure of less than 10 mm Hg (p less than 0.001). A V wave greater than or equal to 140% of end-diastolic IVC dimension was recorded in 75% of patients with severe tricuspid insufficiency, but in no patient with mild or no tricuspid insufficiency (p less than 0.001). The inspiratory decrease in IVC dimension correlated with radionuclide right ventricular ejection fraction (r = 0.75, p less than 0.001); no respiratory variation in end-diastolic IVC dimension occurred in patients with significant right ventricular dysfunction (right ventricular ejection less than 25%) or in patients with constrictive pericarditis.

Blood Pressure↗
PubMed2003

Reduction of 99mTc-sestamibi and 99mTc-tetrofosmin uptake in MRP-expressing breast cancer cells under hypoxic conditions is independent of MRP function.

Hypoxia reduces the uptake of technetium-99m sestamibi (MIBI) in human cancer cell lines. In the current investigation, we attempted to identify the relationship between hypoxia-induced alteration of (99m)Tc-MIBI accumulation and expression of multi-drug resistance-associated protein (MRP) in the MCF7/WT breast cancer cell line and its subclonal cell line, MCF7/VP, which expresses high levels of MRP1. A second cationic compound, (99m)Tc-tetrofosmin (TF), was also examined. Cellular uptake of (99m)Tc-MIBI and (99m)Tc-TF was significantly higher in parental MCF7/WT cells than in MCF7/VP cells. Hypoxic conditions generated with a mixture of 95% N(2) and 5% CO(2) reduced cellular uptake of the two tracers in both parental MCF7/WT cells and MRP1-expressing MCF7/VP cells. Cell binding assay with iodine-125-labelled anti-MRP1 antibody demonstrated its specific binding to MCF7/VP cells. Hypoxia did not affect the amount of antibody bound to MCF7/VP cells. These results indicate that hypoxia-induced reduction of tracer uptake in tumour cells is a phenomenon independent of MRP function.

Biomarkers, Tumor↗
PubMed1981

Diagnosis through imaging: generation, detection, and classification.

Diagnosis is so much a part of medical practice that is function is second nature to physicians, who diagnose repeatedly without giving much thought as to how it works or the kinds of information it generates. Theoretical attributes of the process are of no practical concern to most physicians, as long as diagnosis serves well the purposes of patient care. In this era of accounting for costs and being accountable for quality care, a deeper understanding may be necessary if we are to improve the use of diagnostic procedures, especially in the selection of imaging modalities, the technology of which has proliferated into a variety of sophisticated systems that produce a complex mass of information. Therefore, a look at diagnosis from a more basic perspective may be of more than passing interest to practicing physicians. The above-stated unifying principles elucidate basic attributes of diagnosis and provide an understanding that should aid in the selection of procedures.

Brain↗
PubMed1999

Computer evaluation of left ventricular wall motion by means of shape-based tracking and symbolic description.

Relevant cardiac pathologies manifest themselves as abnormal movements of left ventricular (LV) myocardial wall. An objective quantification is usually accomplished by computer analysis of temporal sequences of LV contours, as obtained by angiography or echography. However the choice of the reference system for measuring motion is still open to discussion. Simple geometric models cannot deal with the non-uniform myocardial fibre structure, which gives rise to non-rigid movements, asynchronous even in normal subjects. Therefore, a new method, Curvature-Motion (CM), was developed for improving motion assessment. Since LV contour shape and position change smoothly throughout the cardiac cycle, the points of curvature extremes are tracked frame-to-frame and selected by exploiting physiologically-based assumptions; then, the points lying among these landmarks are mapped onto sequential contours, according to local displacements and curvature changes. In this way point-trajectories are allowed to be curvilinear and different in systole and diastole. CM gave no significant differences in estimating the known motion of computer-generated contours (R=0.88), unlike other methods commonly adopted (R<0.80). Moreover, for the evaluation of regional wall motion of a preclassified set of angiographic contours, CM showed a greater specificity (88%) and accuracy (90%) with respect to the centre-line method (respectively 83% and 87%). Finally, a fuzzy logic inference system is proposed for translating significant motion patterns from the quantitative form, as provided by the analysis method, into the linguistic terms used by cardiologists in their clinical examinations. This makes the interpretation of quantitative analysis easier and allows medical users to interact with the system for searching particular properties in a single clinical report as well as in a large database.

Algorithms↗
PubMed1993

Retro runner with ischial tuberosity enthesopathy.

In reviewing the literature, no studies were found reporting the use of retro running on flat and hilly terrain, which elicited enthesopathy (stress reaction) at the ischial tuberosity. Therefore, this case study of an atypical enthesopathy condition warrants careful scrutiny in order to generate future research. This case study describes the clinical management of a female runner with bilateral patellofemoral pain who self-initiated a program of backward running and stationary bicycling after reading an article about retro running in a runners' magazine. She subsequently developed ischial tuberosity enthesopathy verified by scintigraphy (bone scan). Her symptoms gradually resolved with physical therapy intervention. Eventually, she was able to forward jog 2 miles on flat surfaces without complaint of pain but did not resume retro running. This case not only suggests the need for further research in retro running kinetics and kinematics but highlights the proactive role health professionals must assume in injury prevention.

Adult↗
PubMed1978

New aspects of cerebrospinal fluid dynamics in humans investigated by sequential gammacamera cisternography, with data evaluation by the digital multichannel analyzer. Part 3: Physiopathology of the ventricular reflux.

Although well described and intensively used for diagnostic purposes, the ventricular reflux as a gammacisternographic phenomen has not yet been satisfactorily explained, and its physiopathology is a subject of controversy. Based on our method of quantitative gammacisternography and gammaventriculography we study the evolution of the tracer concentrations in two main chambers:--the basal cisterns together with the upper cervical canal, considered as a functional unity (the distribution area) and--the ventricular system. We propose the mathematical analysis of a theoretical model which represents the normal and pathological situations of these two chambers, as a method for measuring ventricular volume and ventricular tracer clearance. From the correlation in results with patients and models, we suggest turbulence as the main factor in generating backmixing or total mixing, the appearance of which is called ventricular reflux. We deny the existence of a real inversion of CSF flow. The spinal canal velocity of isotope flow is proposed as additional evidence of turbulence. The normal general dynamics of CSF are delineated, and we propose the following factors that lead to ventricular reflux:--partial obstruction to epicortical CSF flow;--total obstruction to epicortical CSF flow. Their principal characteristics are given, and the importance of using their quantitative parameters in descriptions of patients is stressed. Different aspects in the evolution of hydrocephalus, transependymal resorption, and factors involved in hydrodynamic changes etc. are discussed.

Cerebral Ventriculography↗
PubMed1980

Studies of skeletal tracer kinetics. IV. Optimum time delay for Tc-99m(Sn) methylene disphosphonate bone imaging.

The kinetics of the skeletal tracer Tc-99m(Sn)methylene diphosphonate (Tc-MDP) were studied in four older patients without significant bony disease by means of compartmental analysis. Solution of the model was obtained by digital computer techniques. Tracer concentrations for "target" and "background" areas (to reflect "bone" and "soft-tissue" regions) as time functions were generated for three different imaging criteria: counting rate, a figure of merit, and contrast. The figure of merit reached a maximum early in the second hour after dose administration, but contrast was found to attain a plateau at 6 hr. Either of these criteria is in accord with recommendations in the literature for optimal imaging delay time with Tc-MDP. Bone biopsy in one patient was in good agreement with the model's prediction. Compartmental analysis provides an objective method for determining the optimal imaging delay time, depending on the criterion chosen. The method can be used for any radiopharmaceutical if the compartmental model is known and can be solved.

Aged↗
PubMed1991

Calculation of effective dose-equivalent responses for external exposure from residual photon emitters in soil.

Effective dose-equivalent responses have been calculated for external exposure from residual photon emitters in soil. The calculations are based on the assumption that the receptor is located 1 m above the contaminated ground. A Monte Carlo algorithm was developed to perform the photon transport calculation for the soil/air configuration, in which the soil constituents were assumed to be similar to those of the earth's crust. Photon cross-sections for soil were based on the latest cross-sectional information generated by the U.S. National Institute of Standards and Technology. For every incident photon at the receptor, an estimate of the air-absorbed dose was calculated first and then converted into the effective dose equivalent. The effective dose equivalent is based on the concept of weighted organ doses, as recommended by the ICRP. The ICRP's latest conversion coefficients were used to transform point air-absorbed doses into effective dose equivalents. Baseline effective dose responses were obtained for monoenergetic photon sources assumed to be distributed uniformly in soil for energies ranging from 0.01 to 10 MeV, soil thicknesses from 0 to 5 mean-free-path (mfp) lengths, and soil densities from 1 to 2 g cm-3. On the basis of the calculated dose responses, empirical relationships were obtained for correlating the dose responses with the soil depths and densities for each source energy. The derived correlations contain a convenient exponential form that describes the depth-dose relationship for an estimated accuracy within about 15%; soil densities show an inverse relationship with dose responses. Results of the effective dose-equivalent response can be used to calculate effective dose-equivalent responses for gamma-emitting radionuclides that are commonly identified as residual radioactive materials in soil.

Algorithms↗
PubMed1975

Abnormal brain scans in multiple sclerosis.

A 25 year old man, with a family history of multiple sclerosis in two preceding generations, developed transient sensory changes and incoordination, initially on the left side, and then several months later on the right side in association with an elevated CSF gamma globulin. This was followed by an acute optic neuritis. During the latter episode he developed a positive brain scan which was unaccompanied by any clinical findings explained by a lesion in that area. Cerebral arteriography was normal and the brain scan returned to normal four weeks later, possibly as a result of blood brain barrier restoration. Abnormal brain scans appear to occur only during acute exacerbations of demyelinating disease, and multiple sclerosis should be part of the differential diagnosis of a positive brain scan in a person in the appropriate age range.

Adult↗
PubMed1992

[Radioaerosol inhalation and perfusion imaging studies in immediate postoperative phase after lobectomy].

In order to determine the changes in pulmonary ventilation-perfusion imaging after lobectomies, we examined 11 patients using radioaerosol inhalation and perfusion scintigraphies, before and after the operations. We employed 99mTc-labeled albumin aerosol generated by a jet nebulizer for the inhalation imaging, and 99mTc-labeled macroaggregated albumin for the perfusion imaging, respectively. Prior to the operations, there were no (major) defects of imagings on the lung fields. Immediately after the operations, however, we could not detect any abnormal findings on chest roentgenograms, we found detects of imagings on the lung fields in either inhalation or perfusion scintigraphy whose area were mismatching. It took more than 3 weeks for these defects of imagings to disappear. In conclusion, these findings suggest that postoperative hypoxemia might be occurred by these mismatchings.

Administration, Inhalation↗
PubMed2003

Measurement of left ventricular volumes and ejection fraction by quantitative gated SPET, contrast ventriculography and magnetic resonance imaging: a meta-analysis.

All previous validation studies of quantitative gated single-photon emission tomography (QGS) have examined relatively few patients, and the accuracy of QGS thus remains uncertain. We performed a meta-analysis of data from 301 participants in ten studies that compared QGS using technetium-99m-labelled tracers with contrast left ventriculography (LVG), and from 112 participants in six studies that compared QGS with magnetic resonance imaging (MRI). Linear regression and Bland-Altman analyses were used to evaluate pooled data from individuals across the studies. The correlation between QGS and LVG for end-diastolic volume (EDV) (r=0.81, SEE=27 ml), end-systolic volume (ESV) (r=0.83, SEE=18 ml) and ejection fraction (EF) (r=0.79, SEE=8.3%) was good, as was that between QGS and MRI for EDV (r=0.87, SEE=34 ml), ESV (r=0.89, SEE=27 ml) and EF (r=0.88, SEE=7.2%). However, Bland-Altman plots indicated that LVG minus QGS differences for EDV generated a systematic and random error of 32+/-58 ml (mean+/-2SD), and that MRI minus QGS generated an error of 13+/-73 ml. In the subgroup of patients in whom ECG gating was set at eight intervals, QGS significantly underestimated EF by 7.6%+/-17.4% (mean+/-2SD) compared with LVG and by 6.3%+/-14.6% compared with MRI; no such underestimation was observed in the subgroup in whom ECG gating was set at 16 intervals. We conclude that in patients with ECG gating set at eight intervals, QGS systematically underestimates LV volumes and EF compared with both LVG and MRI. Since QGS also shows considerable variations around the systematic deviations, there remains uncertainty over whether an individual value determined with QGS approximates the true LV volumes and EF.

Aged↗
PubMed2001

[Quantitative evaluation of esophageal scintigraphy in systemic sclerosis].

BACKGROUND: Esophageal involvement by systemic sclerosis (SSc) is frequent. The purpose of this study was to evaluate esophageal motility disorders quantitatively. METHODS: We investigate esophageal scintigraphy in 22 patients with SSc. Esophageal scintigraphy was obtained with swallowing physiological saline in supine position, and swallowing soup in supine and sitting positions. Data was acquired with 0.5 sec per frame for 192 frames in the anterior view. We employed a condensed image as a visual evaluation, half-life and retention rate as a quantitative evaluation, which were obtained from time-activity curves generated from regions of interest on the whole esophagus. The half-life and retention rate were compared with classification of Barnett, stages of SSc, and modified Rodnan total skin score (TSS). RESULTS: No significant differences were seen in classification of Barnett and the stages of SSc. No significant difference was seen between swallowing water and soup in the supine position. The retention rate was significantly prolonged in the supine position than in the sitting position. The retention rate of soup study in the sitting position correlated with TSS (r = 0.61). CONCLUSION: Esophageal scintigraphy in the sitting position is useful in evaluation of esophageal motility in SSc.

Adult↗
PubMed1991

Effect of exercise supplementation on dipyridamole thallium-201 image quality.

To determine the effect of different types of exercise supplementation on dipyridamole thallium image quality, 78 patients were prospectively randomized to one of three protocols: dipyridamole infusion alone, dipyridamole supplemented with isometric handgrip, and dipyridamole with low-level treadmill exercise. Heart-to-lung, heart-to-liver, and heart-to-adjacent infradiaphragmatic activity ratios were generated from anterior images acquired immediately following the test. Additionally, heart-to-total infradiaphragmatic activity was graded semiquantitatively. Results showed a significantly higher ratio of heart to subdiaphragmatic activity in the treadmill group as compared with dipyridamole alone (p less than 0.001) and dipyridamole supplemented with isometric handgrip exercise (p less than 0.001). No significant difference was observed between patients receiving the dipyridamole infusion, and dipyridamole supplemented with isometric handgrip exercise. We conclude that low-level treadmill exercise supplementation of dipyridamole infusion is an effective means of improving image quality. Supplementation with isometric handgrip does not improve image quality over dipyridamole alone.

Adult↗
PubMed1998

[Investigation on feasibility of using a gamma camera for the measurement of blood radioactivity].

The present study was undertaken to determine whether gamma cameras can be used to measure radioactivity in samples, e.g. in blood. Aqueous 123I solution with a concentration of 10.3 MBq/ml was infused at a volume of one ml into a blood-sampling vial having an internal diameter of 22.5 mm. Various concentrations of radioactivity were generated by leaving the vial and taking radioactive decay into account. Static images were acquired for five minutes with a gamma camera using a 64 x 64 matrix to measure radioactivity counts, and the regions of interest with 7 x 7 pixels (21 mm x 21 mm) were defined on the image. The results showed that there was a good linear correlation between the radioactivity counts measured with the gamma camera without collimator and those measured with the well-type scintillation counter in the range between 0.032 kBq/ml and 279 kBq/ml. It therefore appears that gamma cameras can be substituted for well-type scintillation counters in the measurement of radioactivities in samples.

Blood↗