Gerhard F. Fueger

Parathyroid scintigraphy: comparison of technetium-99m methoxyisobutylisonitrile and technetium-99m tetrofosmin studies

We report the preliminary results of a prospective study demonstrating tetrofosmin uptake in surgically and histologically proven parathyroid adenomas. In ten patients with primary chronic hyperparathyroidism, parathyroid imaging was performed using (1) technetium-99m methoxyisobutylisonitrile (MIBI) and (2)99mTc-1,2-bis(bis(2-ethoxyethyl)phosphino)ethane (tetrofosmin) within a time interval of 3–5 days. Both tracers correctly identified the parathyroid adenomas by focal prolonged tracer retention. On visual inspection image contrast was generally higher with MIBI than with tetrofosmin in all the patients studied. Tetrofosmin showed a slower elimination from the parathyroid adenomas than MIBI in six of the ten cases. Our preliminary results show that tetrofosmin, like MIBI, as a feasible, sensitive tracer for parathyroid scintigraphy. For routine use, the rapid kit preparation without heating and the lower radiation dose to the patient make tetrofosmin an alternative tracer for parathyroid scintigraphy. Further evaluation is needed to determine which of the two tracers is the more sensitive for the detection of parathyroid adenomas, and which tracer properties better reflect the degree of endocrine activity.[/p]

Quantitative Bestimmung der linksventrikulären Myokardperfusion mittels EBCT

ZusammenfassungDie myokardiale Perfusion stellt einen wesentlichen Parameter der funktionellen. Determinanten des Herzens dar. Die Bestimmung dieses Parameters mittels direkter Meßverfahren in vivo am Menschen ist nicht vertretbar. So kommen verschiedene indirekte Meßmethoden (Fremdgas-, Thermodilution-, Dopplerkatheter- und radioaktive Techniken) zum Ensatz. Seit der Entwicklung der Electron-Beam-computertomographischen Technologie ist es möglich geworden, nicht nur die linskventrikulären Volumina zu bestimmen, sondern auch die myokardiale Perfusion in ml/100 g/min zu berechnen. Die Messung der linksventrikulären Myokardperfusion erfolgt hierbei im sogenannten Multi-Slice-Flow-Mode in “short axis view”. Hierbei wird der Untersuchungstisch mit dem Patienten 25° nach rechts und 15° nach kaudal gekippt. Nach einem Lokalisationsscan zur Bestimmung der Lage des linken Ventrikels wird der Tisch mit dem Patienten so positioniert, daß sich die voraussichtliche Mitte des linken Ventrikels im Meßfeld der dritten und vierten CT-Schicht befindet. Nach intravenöser Kontrastmittelapplikation von 50 ml und einem Flow von 3 ml/s werden 13×6 CT-Schichten EKG-getriggert jeden zweiten oder dritten Herzschlag angefertigt. Auf der Befundkonsole werden die Regions of Interest so in das linksventrikuläre Myokard gelegt, daß ein Partialvolumeneffekt seitens der benachbarten Struktur möglichst gering gehalten wird. Dies erfolgt 13 mal in jeder CT-Schicht. Zusätzlich werden CT-Werte-Änderungen im Lumen des linken Ventrikels wiederum 13 mal bestimmt. Aus der maximalen Steigung der arteriellen myokardialen Zeit-CT-Werte-Kurve wird nach Division durch die Differenz des maximalen CT-Wertes und des Präkontrast-CT-Wertes im linken Ventrikel die myokardiale Perfusion in ml/100 g/min berechnet. Im Rahmen dieser Studie wurden zusätzlich die linksventrikulären Volumina, wie EDV, ESV, SV, bestimmt und daraus AF und HZV errechnet, und zwar aus CT-Aufnahmen des linken Ventrikels, angefertigt in “long axis view”. Bei neun untersuchten Patienten betrugen die gemessenen globalen myokardialen Perfusionswerte 70 ml/100 g/min (minimal 32 und maximal 116 ml/100 g/min). Dieser Mittelwert entspricht 5% des Herz-Zeit-Volumens unter der Annahme, daß das mittlere Herzgewicht dieser Patienten 300 g beträgt. Die mittels EBCT bestimmte linksventrikuläre Muskelmasse betrug in dieser Studie im Durchschnitt 130 g. Der Vergleich der koronarangiographischen Befunde dieser Patienten mit den gemessenen Perfusionswerten zeigte, daß es nicht ausreichend ist, nur die absolut gemessenen Perfusionswerte zu betrachten, sondern daß diese unter Berücksichtigung des jeweils gemessenen Herz-Zeit-Volumens beurteilt werden müssen. Weitere Studien genau definierter Patienten-gruppen sind erforderlich, um Perfusionsnormwerte unter Ruhebedingungen bei Patienten mit und ohne einer Koronargefäßerkrankung zu bestimmen, da vergleichende Auswertungen mit szintigraphischen Verfahren methodisch bedingt problematisch erscheinen. Die bisherigen Ergebnisse zeigen, daß es mittels EBCT trotz aufhärtungsbedingter Artefakte auch unter klinischen Bedingungen möglich ist, myokardiale Perfusionsmessungen durchzuführen. Ihre Interpretation muß jedoch vorläufig unter Berücksichtigung der funktionellen Parameter, einschließlich der Herzfrequenz, insbesondere jedoch unter Berücksichtigung des Herz-Zeit-Volumens erfolgen.SummaryMyocardial perfusion is one of the most important functional parameters of the heart. Presently various indirect methods are used to determine coronary blood flow or myocardial perfusion as inertgas-, thermodilution-, Doppler catheter- and radiopharmacological techniques.Electron-beam-computed-tomographical technology is able to perform CT data acquisition with a very short exposure time of 50 ms. Using this method it is not only possible to determine left ventricular volumes but also to measure myocardial perfusion in ml/100 g/min. The measurement of the left myocardial perfusion is performed using the short axis view. This position is obtained by moving the table 25 degrees to the patient’s right and 15 dégrees caudally. To determine the position of the left ventricle, a localization scan is obtained in multi-slice-mode using all for target-rings, thus obtaining 8 tomographic levels over 68 mm (each tomographic level having a slice thickness of 7 mm, with an interslice gap of 4 mm between each two adjacent tomographic levels). In this short axis position, using the multi slice flow mode with 3 target-rings and after administration of 50 ml of contrast medium intravenously with a flow of 3 ml/s, 6 tomographic levels are imaged Each tomographic level is obtained 13 times at 80% of the R-R-interval at each 2 or 3 heart beat (ECG-gated). The left ventricular myocardial contrast enhancement is measured by drawing manually the outline of the left ventricular myocardium using time-density-software of the Imatron workstation. For calculation of the myocardial perfusion the socalled “slope method” is used and the results are expressed as the maximum slope of enhancement of the myocardium divided by the difference of the precontrast and peak CT-value in the left ventricle. The global myocardial perfusion is calculated as a mean of all evaluated tomographic levels.In this study left ventricular volumes as enddiastolic volume endsystolic volume and stroke volume were measured and ejection fraction and cardiac output calculated. The measurements were performed in the long axis view. This view is obtained by moving the table 15 degrees to the patients left in a horizontal position. In this long axis position 6 tomographic levels are imaged using the multi-slice-cine-mode with 3 targetrings after administration of 50 ml of contrast medium intravenously with a flow of 3 ml/s. Each tomographic level is obtained 13 times starting at 0% of the R-R-interval (ECG-triggering). The exposure time is 50 ms with an interscan time delay of 8 ms. In 9 studied patients of whom one had 3 significant coronary artery stenotic, lesions (>50%), 2 patients had each 2 non significant stenotic lesions (<50%) and 6 revealed nearly normal coronary angiograms. The mean global myocardial perfusion was 70 ml/100 g/min (min. 32 and max. 116 ml/100 g/min). This mean value of 70 ml/100 g/min is reflecting 5% of the cardiac output supposing that the mean heart weight of these patients was 300 g. In this study the mean of the left ventricular muscle mass determined by the use of EBCT was 130 g. A comparative evaluation of coronary angiographic findings in these patients with the measured myocardial perfusion, values revealed, that it is not sufficient to look only at the absolute values of the measured myocardial perfusion. Furthermore it seems to be necessary to interprete these perfusion values with respect to the calculated cardiac output.Additional studies of well defined patients groups are necessary to determine normal values of myocardial perfusion at rest in patients with and without coronary artery disease. This seems to be important as comparative analysis of myocardial scintigraphic and EBCT-studies is difficult because of methodical inherent differences. The results of this study suggest that despite the presence of some beam hardening artifacts it is possible to measure myocardial perfusion using EBCT in patients with suspected coronary artery disease in the daily clinic workup. For the interpretation of these myocardial perfusion values it is necessary to pay special attention to heart rate and especially to the calculated cardiac output.

First experiences with technetium-99m furifosmin as tumour-seeking agent in breast cancer and recurrent ovarian cancer

Recent in vitro studies suggest that technetium-99m furifosmin may have tumour-seeking properties. We analysed the diagnostic value of99mTc-furifosmin scintigraphy in nine patients with documented carcinoma of the breast and in eight patients with continued recurrent ovarian cancer. In the breast,99mTc-furifosmin failed to visualize the primary malignant tumour and the associated malignant lymph nodes in all patients. In contrast, multiple sites of increased tracer uptake were demonstrated in one patient with acute benign inflammatory breast disease. In four of eight patients with recurrent ovarian cancer,99mTc-furifosmin scintigraphy demonstrated early (5 min p.i.) localized increased uptake corresponding to adhesions to the bowel as diagnosed by computed tomography, but failed to reveal further abnormalities in all patients. The present study demonstrates that furifosmin is of no value in the imaging of breast cancer and recurrent ovarian cancer. These results do not continue the pattern observed in cell culture studies and are quite in contrast to the findings of mammoscintigraphy using99mTc-methoxyisobutylisonitrile and99mTc-tetrofosmin.

Photoaccentuated erythroderma associated with CD4+ T lymphocytopenia: Successful treatment with 5-methoxypsoralen and UVA, interferon alfa-2b, and extracorporeal photopheresis

We describe a 53-year-old HIV-negative white man who had chronic CD4+ T lymphocytopenia and photoaccentuated erythroderma with lymphoma-like histologic changes. The erythroderma completely responded to 5-methoxypsoralen and UVA (PUVA), interferon alfa-2b, and extracorporeal photopheresis. During therapy opportunistic skin infections, including tinea corporis, warts, and disseminated molluscum contagiosum, developed. Although the patient met the current definition of idiopathic CD4+ T lymphocytopenia (ICTL), we cannot rule out the possibility that this peripheral CD4+ T lymphocytopenia resulted from sequestration of CD4+ T lymphocytes in erythrodermic skin.

Cholescintigraphy in the evaluation of bile flow after Roux-en-Y hepatico-jejunostomy and hepatico-antrostomy in infants with choledochal cysts

Background. The study tests the hypothesis that stasis of bile in the Roux-en-Y hepatico-jejunostomy (RYJS) loop might facilitate biliary reflux and cause cholangitis, whereas quicker transit times in hepatico-antrostomy (HAST) might prevent cholangitis. Materials and methods. Cholescintigraphy was performed using Tc99m-trimethyl-Br-IDA in seven RYJS patients and in five HAST patients. Results. The time to peak (Tmax) within the RYJS loop occurred between 18 and 50 min postinjection in all patients and the mean transit time (MTT) ranged between 42 and 69 min in 5/7 patients. Prolonged clearance of the tracer from the liver was seen in 2/7 RYJS patients, in whom the MTT was 77 and 240 min, respectively. In the HAST group, the Tmax within the anastomosed antrum occurred between 5 and 33 min postinjection, and the MTT ranged between 42 and 44 min in 2/5 patients. Protracted tracer uptake in the liver in one patient and localised tracer retention in the left hepatic bile ducts in 2/5 patients caused prolonged MTTs. Recurrent cholangitis and diarrhoea occurred in 4/7 RYJS patients, but in none of the HAST patients. Elevated gastrin levels after RYJS contrasted sharply to normal gastrin levels after HAST. Conclusion. The findings on cholescintigraphy did not differ significantly between RYJS and HAST and provided no explanation for the distinctly different postoperative clinical course of both surgical methods. Nevertheless, we consider cholescintigraphy to be an efficient and cost-effective diagnostic modality for evaluation of the surgical outcome as regards biliary flow.

Parathyroid scintigraphy: First experiences with technetium(III)-99m-Q12

We report the preliminary results of a prospective study demonstrating technetium(III)-99m furifosmin (Q12) uptake in histologically proven parathyroid adenomas. Scintigraphy was performed in 12 patients with hyperparathyroidism. Q12 correctly identified the parathyroid adenomas by focal prolonged tracer retention in ten of the 12 patients. In the two patients without localized tracer retention, no parathyroid adenoma could be identified surgically, either. The retention half-times ranged from 0.5 to 1.8 h (mean 1.27) in the parathyroid adenomas and from 0.3 to 1.2 h (mean 1.05) in the thyroid gland. Our preliminary results show that Q12 is a feasible, sensitive tracer for parathyroid scintigraphy. In comparison to sestamibi (MIBI) and tetrofosmin, Q12 displays short retention in the thyroid gland, which would seem rather advantageous. Further evaluation is needed to determine which among Q12, tetrofosmin and MIBI is most sensitive for the detection especially of small parathyroid adenomas, and which tracer properties will best reflect the degree of endocrine activity.

Correlation of EBCT and TL-201-SPECT Scintigraphy in Patients with Coronary Heart Disease

The aim of the study was to compare the findings of EBCT with those of Tl-201-scintigraphy. 12 patients with CAD were investigated. The 14 fixed Tl-defects were associated with coronary artery stenosis of more than 50% in 5 cases, with atherosclerotic plaques in 2 cases. The 7 non-persisting defects were associated with coronary artery stenosis of more than 50% in 3 cases, with irregularities of the arterial wall in 3 cases, and with atherosclerotic plaques in 2 cases. Contractility and athrophy as seen on EBCT did not correlate with typical findings on scintigraphy. The preliminary data show that EBCT and Tl-scintigraphy do not replace but complement each other.

A review of the Scientific highlights at the European Association of Nuclear Medicine Congress, Vienna 1991

The ]991 Congress of the European Association of Nuclear Medicine took place in Vienna at the Austria Center from September 1 through 5, ]991. The President, spiritus rector and organizer of the event was Prof. Rudolf Hoefer. The International Scientific Committee consisted of O. Schober (chairperson), K.E. Britton, D. Comar, F. Fazio, G.F. Fueger, E. Ogris, E.K.J. Pauwels, G. Riccabona and A. Todd-Pokropek. The organization was carried out by the Vienna Academy of Postgraduate Medical Education and Research. The meeting was attended by just over 2000 scientific participants, 330 accompanying persons, 820 exhibitors and 30 visitors to the industrial exhibition. The attendees had come from 46 countries in Europe, the Near East, Africa, Asia and USA. The programme consisted of a prolific series of scientific sessions of 227 oral presentations, a multitude of poster presentations (429), a continuing education series for technologists and a successful social programme to which Vienna and its surroundings served as a magnificent backdrop. The scientific content consisted of 69% clinical nuclear medicine, 15% radiopharmaceuticals and 16% physical science contributions; of the 1263 abstracts originally submitted, 583 could not be accommodated for presentation by the international scientific committee. Nuclear medicine in 1991 has again shifted its emphasis, and new frontiers are emerging. The quantification of physiological functions, guidance of medical therapy and definition of biological end-points gained more interest. As ever, nuclear medicine has contributed to the understanding of disease processes and has mediated new physiological insights created by the remarkable scientific creativity. Clinical applications continue to spread, and nuclear medicine is challenged to provide physiological measurements of consistently reliable accuracy to guide various forms of therapy requiring a high standard of technical competence. In view of the changes in the financing of health care either contemplated or decided upon in many European countries, nuclear medicine is challenged to contribute decisively to the management of patients, rather than to add complementary or further diagnostic information. Radionuclide therapy