Dissecting transmetalation reactions at the molecular level: C-B versus F-B bond activation in phenyltrifluoroborate silver complexes.

The gas-phase unimolecular reactions of the silver(i) complex [Ag(PhBF3)2]-, formed via electrospray ionisation mass spectrometry of solutions containing the phenyltrifluoroborate salt and AgNO3, are examined. Upon collision induced dissociation (CID) three major reaction channels were observed for [Ag(PhBF3)2]-: Ph- group transfer via a transmetalation reaction to yield [PhAg(PhBF3)]-; F- transfer to produce [FAg(PhBF3)]-; and release of PhBF3-. The anionic silver product complexes of these reactions, [LAg(PhBF3)]- (where L = Ph and F), were then mass-selected and subjected to a further stage of CID. [PhAg(PhBF3)]- undergoes a Ph- group transfer via transmetalation to yield [Ph2Ag]- with loss of BF3. [FAg(PhBF3)]- solely fragments via loss of BF4-, a reaction that involves Ph- group transfer from B to Ag in conjunction with F- transfer from Ag to B. Density functional theory (DFT) calculations on the various competing pathways reveal that: (i) the overall endothermicities govern the experimentally observed product ion abundances; (ii) the Ph- group and F- transfer reactions proceed via late transition states; and (iii) formation of BF4- from [FAg(PhBF3)]- is a multistep reaction in which Ph- group transfer from B to Ag proceeds first to produce a [FAgPh(BF3)]- complex in which the BF3 moiety is initially weakly bound to the ipso-carbon of the phenyl group and then migrates across the linear [FAgPh]- moiety from C to Ag to F yielding [PhAg(BF4)]-, which can then dissociate via loss of PhAg.

Quantitative bone scintigraphy in patients with hyperparathyroidism.

Laboratory tests, including the determination of parathormone in serum, and x-ray examinations are often of limited value in diagnosing hyperparathyroidism (HPT). In this study, bone scintigraphy was carried out in 15 patients with proven HPT (primary and secondary in patients with chronic renal disease) and 25 normal subjects, to evaluate quantitatively increased bone metabolism. The count density ratios bone to soft tissue (D/S-index) were calculated. In normal, this D/S index averaged 3.66 +/- 0.94 and was significantly (p less than 0.001) different to that of HPT-patients averaging 6.37 +/- 1.64. The quantitative evaluation shows a sensitivity of 73%, a specificity of 100% and an accuracy of 90% for detecting HPT (based on the sample values). Discriminant analysis can be applied to calculate the probability of the presence of HPT (primary and secondary) as a function of the measured D/S index.

Validation of a simplified carbon-14-urea breath test for routine use for detecting Helicobacter [correction of Heliobacter] pylori noninvasively.

A carbon-14 (14C) urea breath test for detecting Helicobacter pylori with multiple breath sampling was developed. Carbon-14-urea (110 kBq) administered orally to 18 normal subjects and to 82 patients with Helicobacter infection. The exhaled 14C-labeled CO2 was trapped at 10-min intervals for 90 min. The total 14C activity exhaled over 90 min was integrated and expressed in %activity of the total dose given. In normals, a mean of 0.59% +/- 0.24% was measured, resulting in an upper limit of normal of 1.07%. In 82 patients, a sensitivity of 90.2%, a specificity of 83.8%, and a positive predictive value of 90.2% was found. The single probes at intervals of 40-60 min correlated best with the integrated result, with r ranging from 0.986 to 0.990. The test's diagnostic accuracy did not change at all when reevaluated with the 40-, 50-, or 60-min sample data alone. Thus, the 14C-urea breath test can be applied routinely as a noninvasive, low-cost and one-sample test with high diagnostic accuracy in detecting Helicobacter pylori colonization.

Quantification of amplitude images of gated radionuclide heart studies: a new universal method.

Absolute quantification in nuclear medicine is difficult because of the individual shape, size, and position of human organs. In this study, a general data processing procedure is presented that allows inter-individual comparison and definition of normal count density pattern of unevenly shaped scintigraphic structures. This new method is demonstrated on Fourier amplitude images of gated heart studies. The information contained in the original irregularly shaped left ventricular amplitude scans was transformed into a standard sized circle by interpolating the radiant profiles of varying length from the original left ventricular ROI into the radii of the standard circle using 720, 360, 180, and 72 sampling angles. Retransformation of the individual left ventricular amplitude image from the standard circle area is feasible with only approximately 1% error with the 180, 360, or 720 sampling steps. As a first application of this new method 20 normal amplitude studies were transferred into the standard circle, which allowed the definition of a statistically normal reference image against which individual left ventricular amplitude images may be compared for documenting areas of significantly depressed amplitudes quantitatively. This simple and unique approach may be applied to most organ-related scans such as brain, kidneys, lung, and liver both in planar and tomographic studies to first create a normal reference image and second, to quantify the significance of locally increased or decreased activity in routine scans automatically.

Reconstruction of Fourier coefficients: a fast method to get polar amplitude and phase images of gated SPECT.

Gated SPECT (GASPECT) during radionuclide ventriculography (RNV) is a time-consuming procedure requiring extended hard- and software. Furthermore, the procedure suffers from poor count statistics. Our method tries to overcome these difficulties by exploiting the count summation effect of Fourier analysis. The sine and cosine coefficients of the first harmonic are extracted from the gated views and reconstructed. This, in fact, results in an improvement of the count statistics by a factor of four combined with a tremendous reduction of disc space requirements. Using short-axis slices, bull's-eye plots of the amplitude and phase of the left ventricle are calculated. Cardiac functions and localization and extent of any malfunction are documented three-dimensionally without superposition.

Specification of regional wall motion abnormalities by phase analysis of radionuclide angiograms in coronary artery disease and non-coronary artery disease patients.

Fourier transform of gated radionuclide ventriculograms (RNV) permits the quantitative evaluation of regional wall motion abnormalities (RWMA) regarding both regional magnitude (amplitude display) and regional time sequence of contraction (phase display). In this study, an attempt was made to further specify coronary artery disease (CAD) and non-CAD RWMA detected on consecutive exercise RNV in 17 patients (pts) with proven severe CAD; or on resting RNV in 24 pts with transmural myocardial infarction (MI) compared with 27 pts after treatment with daunorubicin (DAU). RWMA were defined objectively from parametric images by a decrease of the sectorial amplitude by more than 2 s.d.s of normal as determined by quantification of RNV studies of 20 normal individuals. In 15 out of 17 CAD pts (88%) and in 19 out of 24 MI pts (79%), a significantly decreased regional amplitude was found. Importantly, in all abnormal CAD and MI amplitude scans (100%), a significantly abnormal phase delay in the same region could be noted. In five out of 27 pts on DAU (18%) an apical hypokinesis could be verified. In comparison with CAD pts, however, the phase distribution was normal in all these DAU pts. Thus, standardized phase analysis of RNV data provides a powerful tool for specifying RWMA. It allows a highly specific separation of RWMA caused by exercise-induced ischemia, MI, or DAU.

A general comparison of functional imaging in nuclear medicine with other modalities.

New (noninvasive) diagnostic procedures in medicine (ultrasound [US], digital subtraction angiography [DSA], computed tomography [CT], nuclear magnetic resonance [NMR]) create a need for a review of the clinical utility of functional imaging in nuclear medicine. A general approach that is valid for all imaging procedures is not possible. For this reason, an individual assessment for each class of functional imaging is necessary, taking into account the complexity and sophistication of the various imaging procedures. This leads to a hierarchical order: first order functional imaging: imaging of organ motion (heart, lungs, blood); second order functional imaging: imaging of excretory function (kidneys, liver); and third and fourth order functional imaging: imaging of metabolism (except excretory function). First order functional imaging is possible fundamentally, although with limitations in detail, by all modalities. Second order functional imaging is not possible with US. Third and fourth order functional imaging is a privilege of nuclear medicine alone. Up to now, NMR has not proven clinically useful to produce metabolic images in its true sense. This is due to the fact that the signals used are too weak to provide metabolic information with satisfactory local resolution, even after administration of nonradioactive isotopes. First and second order functional imaging of nonradioactive procedures face severe disadvantages, including difficulties in performing stress investigations, which are essential for coronary heart disease, limited capability for true quantitative information (eg, kidney clearance in mL/min), side effects of contrast media and paramagnetic substances, and high costs. Therefore, nuclear medicine functional imaging turns out to be in a favorable clinical position, even in the presence of the competitive diagnostic modalities that have been developed in recent years.

Regional evaluation of the left ventricular wall motion by radionuclide ventriculography.

ECG gated radionuclide ventriculography was performed in 85 patients with heart disease. From the analysis of time activity curves of each pixel, sets of parametric scans were displayed. Of 496 parametric scans, 192 were normal and 304 showed wall motion abnormalities. There was good correlation between the individual parametric scans (r greater than or equal to 0.815) and between parametric scans and contrast ventriculograms (r greater than or equal to 0.631) in the occurrence and extent of regional wall motion abnormalities. The highest sensitivity was revealed by the peak filling rate (relaxation velocity) scan. The best specificity was shown by scans using the amplitude and phase of the first Fourier element. Good results were obtained by a combination of four parametric images. The ability of the phase scan to detect local dyskinesis may be better than that of the contrast ventriculogram. Changes in parametric scans were related to, but preceded, impairment of left ventricular function (r greater than or equal to 0.513), It is concluded that parametric scans provide a reliable, objective and non-invasive method for regional evaluation of left ventricular function, of great use in the diagnosis of local wall motion abnormalities and their effect on the heart performance.

[Scintigraphic radio-spirometry. Methods and indications]. / Die funktionsszintigraphische Radiospirometrie. Methode und Indikation

Scintigraphic radio-spirometry combines conventional spirometry with the advantages of a functional isotope technique, thereby providing a clinically useful method for the study of pulmonary function. The advantage of the method consist principally in the ability to estimate physiological values separately for the two lungs, and also for selective portions of each lung. The apparatus, method and quantitative evaluation of the results are discussed in detail and the method is critically evaluated. Indications for radiospirometry are given.

[Functional scintigraphic radiospirometry. First clinical results in patients with lung diseases]. / Die funktionsszintigraphische Radiospirometrie. Erste klinische Ergebnisse an lungenkranken Patienten

First clinical results of patients with diseases of the lungs. The previous experiences on patients with diseases of the lungs reveal that the regional function diagnostics of the lungs may be extended and improved by functional scintigraphic radiospirometry. Because of the determination of regional lung volumes restrictive lung diseases can be differentiated and analysed more exactly than it has been possible before by the examinations of perfusion and ventilation alone. A further advance of the determination of lung volume is that the question of functional operability can be cleared up exactly. In our opinion the routine use of the functional scintigraphic radiospirometry is justified. A contraindication for this kind of examination should only be pregnancy.

[Camera-cinematography of the heart (author's transl)]. / Kamera-Kinematographie des Herzens

By "camera-cinematography" of the heart, we mean an isotope method which permits detailed observation of cardiac mechanics without the use of a catheter. All that is necessary is an intravenous injection of 10 to 15 mCi 99mTc human serum albumen followed after ten minutes by a five to ten minute period of observation with a scintilation camera. At this time the isotope has become distributed in the blood. Variations in the precordial impulses correspond with intra-cardiac changes of blood volume during a cardiac cycle. Analysis of the R-wave provides adequate information of cyclical volume changes in limited portions of the heart. This is achieved by a monitor with a pseudo-3-dimensional display; contraction and relaxation of the myocardium can be shown for any chosen longitudinal or horizontal diameter of the heart. Our programme allows simultaneous presentation of the movement of any point on the myocardium as a time-activity curve. The method is recommended as an addition to chest radiography, heart screening or cardiac kymography before carrying out cardiac catheterisation.

[Radionuclide ventriculography as a special case of functional scintigraphy (author's transl)]. / Die Radionuklid-Ventrikulographie als Spezialfall der Funktionsszintigraphie.

Computer processed dynamic scintigraphy (CPDS) (Funktionsszintigraphie), as developed 15 years ago essentially in the German Cancer Research Center (Institute of Nuclear Medicine), Heidelberg, shows limitations with regard to temporal spatial resolution. Under fixed count rate conditions, temporal resolution can only be improved at the expense of spatial resolution. The adverse implications of this inverse relationship may be overcome by the use of trigger techniques, resulting in an improvement in statistical information. The strict application of principles as developed in CPDS in gated blood pool procedures leads to parametric scans (functional imaging) displaying optimal utilisation of available information and presentation of regional wall motion abnormalities.

[Radionuclide ventriculography. I. Fundamentals and methods (author's transl)]. / Radionuklid- Ventrikulographie. I. Grundlagen und Methoden.

Using local time activity curves parameters are calculated which depend on the local wall motion of the heart cavities. These functional parameters allow the determination of the contours of the heart cavities and the assessment of segmental wall motion disorders. The left ventricular ejection fraction has been calculated by enddiastolic and endsystolic counts using a method which takes into account background inhomogeneity.

[Radionuclide ventriculography. III. Clinical results--parameters of regional wall motility (author's transl)]. / Radionuklid- Ventrikulographie. III. Klinische Ergebnisse: Parameter der regionalen Wandbewegung.

Radionuclide ventriculography and cineangiography were performed in 62 patients with suspected coronary artery disease. Regional wall motility irregularities could be demonstrated in 97% of those patients who revealed an irregularity in the cineangiogram. Two small scars of the posterior myocardial wall escaped detection. The sensitivity of the radionuclide ventriculography was 97%, the specificity was 80%, 4 patients with normal cineangiography showed small irregularities in the radionuclide ventriculogram. 70 patients with infarction revealed wall motility irregularities in 90%, whereas perfusion defects could be detected by thallium scintigraphy in 66% (young and old infarctions).

[Value and reliability of blood pool scintigraphy in liver hemangiomas]. / Wertigkeit und Stellenwert der Blutpool-Szintigraphie bei Leberhämangiomen.

In a prospective study the importance and reliability of blood-pool scanning were checked. 40 patients were investigated. In 36 patients sonographical evidence of one or more hemangiomas was shown. 4 patients with 11 primary or secondary tumors in the liver were taken as control group. All tumors could be verified by histology or CT. Differentiation between hemangiomas and other space-occupying lesions (benign and malignant tumors) was possible with high accuracy. We found a sensitivity of 100% in hemangiomas larger than 4 cm, a sensitivity of 78% in hemangiomas larger than 3 cm and a sensitivity of 69% in hemangiomas larger than 2 cm. Falsely positive results were not observed. In conclusion, blood-pool scanning of the liver is a reliable method in the differential diagnosis of hemangiomas.

[Radionuclide ventriculography. II. Clinical results--parameters of global ventricular function (author's transl)]. / Radionuklid- Ventrikulographie. II. Klinische Ergebnisse: Parameter der globalen Ventrikelfunktion.

The ejection fraction as determined by gated blood pool studies was compared with the ejection fraction as evaluated by the following conventional methods: 1) biplane cineangiography employing the Simpson rule. Correlation was r = 0.805 (n = 25); 2) the same patients using the area-length method (r = 0.88, n = 25); 3) monoplane cineangiography using the method of Greene et al. (5) (r = 0.86, n = 35). In 20 patients the maximal contraction velocity as evaluated by radionuclide ventriculography was compared with the mean systolic ejection rate. The observed correlation was weak (r = 0.62, n = 20); however, it should be noted that the radionuclide method determines the maximum contraction velocity whereas cinceangiography measures an average value over the whole systole.

[Determination of endogenous labelling of thyroid hormones during a radioiodide test in euthyroid goiter patients and hyperthyroid patients (author's transl)]. / Messung der endogenen Markierung der Schildduüsenhormone im Rahmen des Radiojodtestes bei euthyreoten Strumapatienten und hyperthyreoten Patienten.

The administration of a diagnostic dose of radioiodide, as in the radioiodide uptake test, results in the formation and secretion of radioactive thyroid hormones (endogenous labelling). In this report a method is described by which thyroid hormones are chromatographically isolated from serum, with the simultaneous assessment of the incorporated radioactivity over a period of time. A low-level counter was used to measure the small amounts of activity present. By this method the hormone phases during a radioiodide uptake test may be better evaluated. The present results show a good diagnostic discrimination between euthyroidism and borderline or definite hyperthyroidism (by a factor of 10 and 40, respectively). The influence of factors such as a small intrathyroidal iodide pool need, or course, to be considered. Hence, by taking into account such parameters as the intrathyroidal iodide pool, the hormone clearance etc, a technique for the measurement of thyroid hormone secretion can be developed.

[The effect of 3-dimensional data stabilization in radionuclide ventriculography on the statistical numerical error in the ejection fraction]. / Einfluss einer dreidimensionalen Datenstabilisierung in der Radionuklidventrikulographie auf den statistischen Zählfehler der Ejektionsfraktion.

The suitability of a 3-dimensional filter in diminishing the statistical noise of left ventricular volume curves without any systematical error in the left ventricular ejection fraction (EF) was investigated. The EF values were compared in 50 studies on 24 patients. There was no significant systematical difference between the EFs before and after filtering. The filter diminishes the statistical uncertainty of the EF by a factor of 0.47. Therefore, the method may possibly be employed in processing the left ventricular volume curves.

[The role of radionuclide ventriculograms in determining the indications for valve replacement in chronic aortic valve insufficiency]. / Die Rolle des Radionuklid-ventrikulogramms für die Indikationsstellung zum Klappenersatz bei der chronischen Aortenklappeninsuffizienz.

Timing of aortic valve replacement (AVR) in chronic aortic regurgitation (AR) remains a difficult problem in clinical practice. Radionuclide ventriculography (RNV) yields information on the extent of valvular regurgitation, the enlargement and the systolic function of the left ventricle. A "well-timed" AVR is defined by 1) postoperative improvement of clinical symptoms, decrease in left ventricular end-diastolic volume (EDV) and normalization of ejection fraction (EF) as well as by 2) greater improvement under surgical therapy as compared to conservative management. In "too early" AVR the latter condition is not fulfilled, while in "too late" AVR the first condition is not accomplished. In this study 54 patients with chronic aortic incompetence were evaluated by RNV to see whether these three groups ("too early", "well timed", "too late" AVR, resp.) can be separated by the relation between EDV and regurgitant volume (RV), the level of the EDV and the clinical status. The examination was based on pre- and postoperative RNV studies as well as on follow-up studies. A good postoperative result can be expected in cases with a preoperative EDV/RV-ratio similar to that observed in 30 patients with AR in whom AVR was not indicated. In contrast, in the majority of those cases with an EDV/RV-ratio exceeding this normal range the postoperative outcome will be unsatisfactory. If the EDV/RV-ratio is normal, AVR should be performed in cases with an EDV exceeding 400 ml, while in cases with an EDV between 300-400 ml AVR is only indicated in the presence of additional symptoms (NYHA greater than or equal to II).(ABSTRACT TRUNCATED AT 250 WORDS)

[Radionuclide ventriculography--a noninvasive method of diagnosis and quantification of tricuspid valve insufficiency]. / Die Radionuklidventrikulographie--eine nichtinvasive Methode zur Diagnose und Quantifizierung der Trikuspidalklappeninsuffizienz.

The diagnosis of tricuspid regurgitation (TR) is difficult to make by simple clinical methods or by invasive techniques. Contrast echocardiography and Doppler echocardiography have improved diagnostic results, but a golden standard is still not available. Radionuclide ventriculography (RNV) is a well-established method for the detection and quantification of a volume load on the left ventricle: the regurgitation fraction can simply be derived from the regurgitant index as the ratio of enddiastolic-endsystolic count-rate differences between the left and right ventricle. In left heart valvular regurgitation a regurgitant index exceeding the upper normal limit can be expected. This study was performed to evaluate the diagnostic accuracy of an abnormally low regurgitant index in detecting TR, which is accompanied by an isolated volume load on the right ventricle. A series of 33 patients with TR on physical examination and cardiac catheterization underwent RNV and was compared with 48 patients with right ventricular enlargement or pressure load on the right ventricle. In addition, the specificity of the method was evaluated in 470 consecutive patients with various forms of heart disease. In 18 out of 20 subjects with isolated TR a regurgitant index below the lower normal limit was found. The remaining 2 cases with minor TR had a regurgitant index within the normal range, which is 0.89 to 1.97 in this laboratory. In patients with additional volume load on the left ventricle, the sensitivity of the method was found to be low, as could be expected from the principle of the method. The time-activity curve over the liver was usually in phase with that recorded over the atria in subjects with TR. Therefore, the additional examination of a region of interest over the liver was particularly useful in these patients with concomitant aortic or mitral valve regurgitation. None of the 48 patients with right ventricular enlargement or pressure load on the right ventricle had a falsely positive result. A total of 17 out of 470 consecutive patients had a regurgitant index below the normal range; left ventricular function was severely impaired in 9 of these patients. The remaining subjects had a regurgitant index slightly below the lower normal limit. In conclusion, RNV has a high sensitivity in the diagnosis of TR in patients without left heart valvular regurgitation and a high specificity in patients without severely impaired left ventricular function and without left-to-right shunt through an atrial septal defect.(ABSTRACT TRUNCATED AT 400 WORDS)