*Klinik und Poliklinik für Nuklearmedizin der Universität Würzburg *Stratec Medizintechnik, Pforzheim; F.R.G. Einleitung Die mittels Knochendichtemessgeräten bestimmte Knochendichte ist als Parameter ein eingeführtes Surrogat für das Frakturrisiko. Die Verformungsteifigkeit des Knochens unter Krafteinwirkung also die Stabilität des Knochens kann durch die Knochendichte nicht beschrieben werden. Dagegen ermöglicht die Kenntnis der Masseverteilung des Knochens bzw. der Architektur eine näherungsweise Berechnung seiner Festigkeit. Die Berechnung des axialen Flächenmomentes (Abb.1) setzt die Kenntnis des Flächenquerschnittes voraus, der sich mit der von uns entwickelten peripheren quantitativen Computertomographie (pQCT) einfach ermitteln läßt. Es wird erwartet, daß sich besser als durch die Knochendichte, die Trennung zwischen Gruppen mit und ohne Radiusfraktur durch die Knochenstabilität beschreiben läßt. Diese Erwartung wird gestützt durch invitro-Untersuchungen[1,2] .

Between May 1990 and February 1991 we enrolled 212 patients of 410 referred to our clinic for bone mass evaluation according to different diagnosis or therapeutic procedures. These patients were divided into 7 groups. The question had to be answered, which method of measurement and which skeletal site would give better information about the influence of the diseases of therapeutic procedures. We measured the areal mineral density of the lumbar spine with dual x-ray absorptiometry (DEXA) and the mineral content of the total and trabecular bone mass of a cross-sectional slice at the distal radius with peripheral quantitative computed tomography (pQCT). The results were statistically analysed. We calculated the percentage deviation from young normals. Trabecular mineral content showed the greatest difference (18% to 44%), compared to the healthy reference group, corresponding to the known higher turnover of this bone compartment. In contrast, the difference of the areal density of the lumbar spine was found to be lowest (4% to 27%). In order to compare the methods objectively, we additionally calculated a ROC-analysis of two postmenopausal groups (51 healthy, 46 osteoporotic) to demonstrate the diagnostic validity. The validity proved to be substantially better when purely trabecular bone at the distal radius was measured. The ROC-curves showed a sensitivity of 84% for radial trabecular bone on a specificity level of 90%, whereas the lumbar spine values presented with a sensitivity of only 68%.

The wide spread use of bone densitometers in Germany and other European countries has required the establishment of a validated reference population data base. A semianthropomorphic forearm cross-calibration phantom (EFP), developed during a concerted research action of the European Union's programme in Biomedical Engineering (COMAC-BME), was used to cross-calibrate the peripheral quantitative computer tomography (pQCT) devices at four German centers participating in the multicenter study. In total, 723 women and 208 men were included in the normal data base. No significant regional differences were found between the data of the different centers. In addition to the manufacturers calibration standard, proper calibration of the pQCT devices could be monitored during collection of the normal female and male data base. As a merit of the COMAC-BME study the measurements obtained with all pQCT devices thus ensured an uniform reference data base for distal radius measurements in Germany.

We propose an automated method for the routine analysis of urinary iodide, using paired-ion reversed-phase HPLC with electrochemical detection and a silver working electrode. Assay conditions include a flow rate of 1.0 mL/min and an operating potential of 0.10 V. The retention time for iodide is 5.4 min. Sample preparation can be semiautomated by use of a reduced-pressure manifold. The detection threshold (signal-to-noise ratio of 3) was 2 pmol, corresponding to 0.04 mumol/L. The within-run precision (CV) for a pooled urine sample was 3.9% at 452 nmol/L iodide. The average recovery of added iodine was 94%. For comparison with a colorimetric method, we measured 177 random (untimed) urine samples by both HPLC (y) and a Technicon AutoAnalyzer acid digestion method (x). After removal of organically bound iodine, the results for unbound urinary iodide determined by the two methods were nearly identical (r = 0.99; y = -0.03 + 1.00x; Sy/x = 0.12 mumol/L). Comparison of total urinary iodine measured by the Technicon AutoAnalyzer with unbound urinary iodide determined by HPLC also showed a high correlation (r = 0.96; y = -0.03 + 0.78x; Sy/x = 0.23 mumol/L), because iodine is excreted in urine mainly as iodide. We conclude that iodine in urine can be accurately determined by the more convenient HPLC assay.

Hyperthyroidism induced by contrast agents in a major problem in patients with pre-existing thyroid disease, particularly in patients with functional thyroid autonomy. The present study was undertaken to evaluate whether contrast media applied during endoscopic retrograde cholangiopancreaticography (ERCP) may result in a significant increase of serum iodine levels and thus may be associated with the risk of iodine-induced hyperthyroidism. The courses of serum concentrations of total iodine and free iodide, as well as of urinary iodine excretion, were measured in 15 patients before and up to 21 days after ERCP. During ERCP, the non-ionic contrast medium iopamidol was instilled in amounts resulting in a total iodine load of 57.4 +/- 22.8 mmol (7.3 +/- 2.9 g). In all patients, ERCP resulted in a highly significant increase in serum levels of total iodine from 0.8 +/- 0.5 to 85.2 +/- 116.9 mumol/l 4 h after application of the contrast agent. In parallel, serum iodide levels were raised from 0.06 +/- 0.04 to 5.42 +/- 6.09 mumol/l and urinary iodine excretion from 71.1 +/- 35.7 mumol/mol creatinine to 621,620.9 +/- 636,492.2 mumol/mol creatinine. Peak concentrations of serum iodine are well related to the total amount of iodine applied (p < 0.05). During follow-up, iodine levels returned to pre-exposure levels within 2-3 weeks. Levels of thyrotropin, free thyroxine, and free triiodothyronine remained unchanged during the follow-up period. In conclusion, endoscopic application of iodinated contrast agents during ERCP leads to significant increases of serum levels of total iodine and free iodide and of urinary iodine excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Thirty patients with clinical signs of infective endocarditis and pathologic echocardiographic findings indicating vegetations underwent scanning with In-111 or Tc-99m hexamethylpropylene amineoxime (HMPAO) labeled granulocytes. Blood cultures were positive in 60% of the patients. The other cases were negative as a result of antibiotic pretreatment. The results of scintigraphy were correlated with the subsequent clinical course, and in 20 cases with data obtained by histologic examination of the valves. With regard to the degree of the inflammatory process, the nuclear medical procedure provided the following results: true-positive in 6 cases, false-positive in 1 case, true-negative in 19 cases, and false-negative in 3 cases. In this study, positive granulocyte scans correlate with high activity of the inflammatory process and predict a poor prognosis for the patients concerned.

Peripheral blood mononuclear cells (PBMC) were taken by leukapheresis from a patient with melanoma skin metastases and stimulated in vitro using 1000 IU recombinant interleukin 2 (IL-2)/ml to generate lymphokine-activated killer cells (LAK cells). Two-colour immunofluorescence analysis demonstrated an IL-2-induced up-regulation of CD25 on natural killer cells (CD56+) as well as on T lymphocytes (CD3+). After radiolabelling with indium-111, the cells were reinfused. Gamma-camera imaging revealed an enrichment at the tumour sites. Immunostaining of tumour tissue taken before and after scintigraphy demonstrated CD25+ T lymphocytes (CD2+, CD3+), but no natural killer cells (CD16+, CD56+) infiltrating the metastases. LAK cell enrichment at melanoma metastases in vivo did not involve natural killer cells, but was characterized by increased numbers of activated T lymphocytes in this patient.

Thirty patients with clinically suspected infective endocarditis were scanned with Indium-111- or Tc-99m-HMPAO-labeled granulocytes. The scans were correlated with the clinical course, and in 20 cases with the results from histologic examination of the valves. In six cases the scintigraphic examination gave correct positive results, in three cases false negative, in one case a false positive, and in 20 cases correct negative results. If we limit the analysis to only the histologically proven cases, our data suggest a specificity of the method of 86 % and a sensitivity of about 67 %.

Thirty patients with clinically suspected infective endocarditis were scanned with Indium-111- or Tc-99m-HM-PAO-labeled granulocytes. The scans were correlated with the clinical course, and in 20 cases with the results from histologic examination of the valves. In six cases the scintigraphic examination gave correct positive results, in three cases false negative, in one case a false positive, and in 20 cases correct negative results. If we limit the analysis to only the histologically proven cases, our data suggest a specificity of the method of 86% and a sensitivity of about 67%.

Between May 1990 and February 1991 we enrolled 212 patients of 410 referred to our clinic for bone mass evaluation according to different diagnosis or therapeutic procedures. These patients were divided into 7 groups. The question had to be answered, which method of measurement and which skeletal site would give better information about the influence of the diseases of therapeutic procedures. We measured the areal mineral density of the lumbar spine with dual x-ray absorptiometry (DEXA) and the mineral content of the total and trabecular bone mass of a cross-sectional slice at the distal radius with peripheral quantitative computed tomography (pQCT). The results were statistically analysed. We calculated the percentage deviation from young normals. Trabecular mineral content showed the greatest difference (18% to 44%), compared to the healthy reference group, corresponding to the known higher turnover of this bone compartment. In contrast, the difference of the areal density of the lumbar spine was found to be lowest (4% to 27%). In order to compare the methods objectively, we additionally calculated a ROC-analysis of two postmenopausal groups (51 healthy, 46 osteoporotic) to demonstrate the diagnostic validity. The validity proved to be substantially better when purely trabecular bone at the distal radius was measured. The ROC-curves showed a sensitivity of 84% for radial trabecular bone on a specificity level of 90%, whereas the lumbar spine values presented with a sensitivity of only 68%.

Between May 1990 and February 1991 we enrolled 212 patients of 410 referred to our clinic for bone mass evaluation according to different diagnosis or therapeutic procedures. These patients were divided into 7 groups. The question had to be answered, which method of measurement and which skeletal site would give better information about the influence of the diseases of therapeutic procedures. We measured the areal mineral density of the lumbar spine with dual x-ray absorptiometry (DEXA) and the mineral content of the total and trabecular bone mass of a crossectional slice at the distal radius with periperal quantitative computed tomography (pQCT). The results were statistically analysed. We calculated the percentage deviation from young normals. Trabecular mineral content showed the greatest difference (18% to 44%), compared to the healthy reference group, corresponding to the known higher turnover of this bone compartement. In contrast, the difference of the areal density of the lumbar spine was found to be lowest (4% to 27%). In order to compare the methods objectively, we additionally calculated a ROC-analysis of two postmenopausal groups (51 healthy, 46 osteoporotic) to demonstrate the diagnostic validity. The validity proved to be substantially better when purely trabecular bone at the distal radius was measured. The ROC-curves showed a sensitivity of 84% for radial trabecular bone on a specificity level of 90%, whereas the lumbar spine values presented with a sensitivity of only 68%.

ECG-gated SPECT radionuclide ventriculography (GASPECT) is well suited for measurement of absolute left ventricular volumes and regional wall motion abnormalities and superior to planar radionuclide ventriculography. As an example for the clinical value of this method the results of a prospective study in patients after first myocardial infarction (MI) will be presented. In 76 patients (39 with small MI and 37 with large MI) volume and hemodynamic measurements were extended from 4 (2-6) days (D) and 4 (3-5) weeks (W) to 6 (5-8) months (M) after myocardial infarction (MI). In small MI, end-diastolic volume [EDVI, (ml/m2)] end-systolic volume [ESVI, (ml/m2)] ejection fraction and stroke volume [SVI, (ml/m2)] remained unchanged. In large MI, ESVI (4D: 38 +/- 3, 4W: 47 +/- 3*, 6M: 52 +/- 3*, *p < 0.05 vs 4D) and EDVI (4D: 72 +/- 3, 4W: 86 +/- 5*, 6M: 92 +/- 5* +, *p < 0.05 vs 4D, + p < 0.05 vs 4W) increased at constant wedge-pressure. SVI remained restored after 4W (4D: 35 +/- 2, 4W: 42 +/- 2*, 6M: 42 +/- 2*, *p < 0.05 vs 4T). These results support the hypothesis, that left ventricular dilatation is compensatory at rest, but non-compensatory when progressive after MI and may result in heart failure. Since patients with progressive left ventricular dilatation may benefit from early administration of ACE-inhibitors, GASPECT can help to identify patients at risk by its high accuracy to measure non-invasively and observer independent absolute volumes and regional wall motion abnormalities.

To investigate the influence of calcitonin deficiency on bone turnover and density we studied 25 premenopausal female and 12 male patients (age 23 to 49 years) who had undergone total thyroidectomy for differentiated thyroid cancer 1 to 15 years previously. Basal and calcium stimulated extractable calcitonin, representing the monomeric, biologically active form of the hormone, was lacking or markedly decreased in all patients. There was a relative increase of urine hydroxyproline excretion (an index of osteoclastic bone degradation) in relation to serum osteocalcin (an index of osteoblastic bone formation) indicating an imbalance of bone turnover with a tendency to increased degradation in all patients. Total and trabecular bone density, measured with quantitative computed tomography at the distal forearm were significantly decreased in the male and normal in the female patients, without a relation to the duration of the calcitonin deficiency. The study indicates that patients with calcitonin deficiency, suppressive thyroid hormone treatment, or both may have a higher risk of increased bone degradation and osteopenia. Whether the effect is more due to calcitonin deficiency or thyroid hormone therapy, cannot be concluded from this study design. The fact that only the male patients had a decreased bone density may be due to a lower parathyroid activity in our female patients and the greater thyroidectomy-induced decrement of monomeric calcitonin in our male patients compared with male controls.