Single-photon emission tomography studies of rubidium-81 in the detection of ischaemic heart disease, using a stress-reinjection protocol.

The present study was designed to determine the feasibility of using single-photon emission tomography (SPET) imaging with rubidium-81 (T1/2 = 4.54 h) to detect ischaemic heart disease, using a stress-reinjection protocol and a specially constructed 511-keV hexagonal hole collimator for a standard gamma camera. The diagnostic performance of 81Rb SPET in detecting coronary artery disease (CAD) was investigated in 52 patients with a high prevalence of CAD. Coronary arteriography was performed in 34 patients, 25 of whom were classified as having significant stenosis (> or = 50%). At peak exercise (Cornell protocol), 111-222 MBq 81Rb was injected i.v. for stress imaging, and after 3 h of rest, 74-111 MBq was reinjected for rest imaging. The displayed short- and long-axis slices and the polar map images were interpreted qualitatively. In comparison to coronary arteriography, which served as the gold standard, the performance of 81Rb SPET revealed a sensitivity of 95% for the detection of CAD. Images of diagnostic quality were obtained in all patients, these being comparable to thallium-201 SPET images. In conclusion, these results indicate that the described method can be routinely used for the positron emitter 81Rb with a conventional gamma camera and special shielding. 81Rb has the well-known advantages of a potassium analogue and 81Rb SPET permits better visualization, particularly of the posterior wall of the myocardium, due to the higher photon energy. Considering the typical dose of 201Tl used for SPET (74-148 MBq), a 81Rb SPET scan imposes a significantly lower radiation burden on the patient.

Mescaline-induced psychopathological, neuropsychological, and neurometabolic effects in normal subjects: experimental psychosis as a tool for psychiatric research.

The psychological, neuropsychological, and neurometabolic effects of the hallucinogenic agent mescaline were investigated in 12 normal men who were volunteers. Mescaline produced an acute psychotic state 3 1/2-4 hr after drug intake, as measured by the Brief Psychiatric Rating Scale (BPRS) and Paranoid Depression Scale (PDS). The Assessment of Altered States of Consciousness (APZ) questionnaire revealed specific effects of mescaline in the visual system. Neuropsychological effects were studied with a face/nonface decision task with known right-hemisphere advantage, in which mescaline induced a decrease of functioning of the right hemisphere. In functional brain imaging using single photon emission computed tomography (SPECT), mescaline produced a "hyperfrontal" pattern with an emphasis on the right hemisphere, which was correlated with mescaline-induced psychotic psychopathology. Our findings question the validity of the concept of hypofrontality as an explanation for schizophrenic symptomatology. The study of psychoactive substances under controlled laboratory conditions has the methodological advantage of intraindividual control, and hence, minimal variability of data.

[Reinjection of 201TL in postinfarct patients so as to improve the demarcation between cicatrix and ischemia]. / Re-Injektion von 201Tl bei Postinfarktpatienten zur besseren Abgrenzung von Narbe und Ischämie.

In patients with earlier myocardial infarction the value of additional imaging after reinjection of 201Tl for better detection of ischemic myocardium was assessed. In 40 patients 40 MBq 201Tl were reinjected 24 h after stress and additional SPECT was performed 1 h later. Quantification of defect sizes showed a further reduction of 4 h redistribution defects by more than 30% in 18 patients. Comparison with clinical, electrocardiographic and scintigraphic parameters showed that none of these was sufficiently accurate for predicting additional thallium uptake after reinjection. In 22 patients with coronary angiography all 11 patients with collateralized occlusions of a coronary artery showed a reduction of the 4 h redistribution defect by > 20%, whereas all patients (5/5) with occlusions without distal collateralization had changes < 20%. This demonstrates that an improved thallium uptake after reinjection is typical of ischemic but vital myocardium.

[Optimized pin geometry for improved retention of parapulpal pins in amalgam]. / Verbesserte Retention parapulpärer Stifte im Amlagam durch Formoptimierung.

The retentive part of parapulpal pins is often very bulky, and this may compromise the strength of the amalgam restoration. This in turn may considerably limit the range of applications of parapulpal pins. For this reason the geometry of the retentive pin portion was optimized with the aid of a finite element analysis. This manoeuvre resulted in a better stress distribution and improved retention, although the pin size was reduced. In clinical terms this implies a wider range of possible applications, because these pins allow safe anchorage of extensive amalgam restorations and do not affect the strength of the restoration.

[99mTc-2-methoxy-isobutyl-isonitrile in the diagnosis of coronary heart disease: results of a multicenter study]. / 99mTc-2-Methoxy-Isobutyl-Isonitril in der Diagnostik der koronaren Herzkrankheit: Ergebnisse einer Multizenterstudie.

A total of 226 patients was studied in a phase-III multicenter trial to compare the results of stress/rest 99mTc-MIBI with 201TI scintigraphy and/or coronary arteriography. The evaluation of planar and SPECT imaging was based on a semiquantitative visual scoring. A congruent diagnosis was generated from all planar 201TI and 99mTc-MIBI scintigrams performed in 36 patients. In 62 of 63 patients, SPECT-studies with 99mTc-MIBI and 201TI led to an identical diagnosis. In one patient a positive result was obtained with 201TI-SPECT whereas 99mTc-MIBI was negative. Segmental agreement for 1509 SPECT segments was 85.7%, for 554 planar segments it was 86.6%. In comparison to coronary arteriography, performed in 180 patients, the overall sensitivity for the correct diagnosis of coronary artery disease (CAD) was 86% for planar MIBI scintigraphy or 92% for MIBI-SPECT. Overall specificity was 100% for planar imaging and 57% for SPECT. The low specificity of MIBI-SPECT was probably due to high prevalence of CAD in this study population. In a subgroup of 43 patients, who underwent coronary angiography, identical results were found with 99mTc-MIBI and 201TI. Only one patient showed a positive scintigraphic result with both 99mTc-MIBI and 201TI without angiographically proven stenosis greater than 50% or prior myocardial infarction. Vessel sensitivities in stenosed coronary arteries (greater than 50% stenosis) were 54% for the LAD and 87% for the RCX/RCA areas with MIBI-SPECT, or 51% or 79% for planar scintigraphy, respectively. Vessel specificities for SPECT were 65% in the LAD or 52% in the RCX/RCA, or 90% or 83% in planar imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

[SPECT studies with 99mTc-HMPAO in Huntington's chorea patients]. / SPECT-Untersuchungen mit 99mTc-HMPAO bei Patienten mit Huntingtonscher Chorea.

Huntington's chorea is an autosomal dominant inherited disease with a chronic course and atrophy of the corpus striatum. PET examination shows reduced glucose metabolism in the caudate nucleus. We examined seven patients with Huntington's chorea by SPECT, using 99mTc-HMPAO. All patients had cortical defects of varying severity. In addition, five patients showed increased uptake in the region of the caudate nucleus. The specific tracer uptake due to the metabolic processes in the region of the caudate nucleus in Huntington's chorea is discussed.

Long-term follow-up using serial serum thyroglobulin determinations in patients with differentiated thyroid carcinoma.

Although thyroglobulin is generally recognized as a useful marker for metastases in cases of differentiated thyroid carcinoma, there have been few reports of the use of thyroglobulin determination for long-term follow-up. This report presents the results of long-term follow-up studies carried out for periods of up to 4 years in 18 patients, including 4 patients with local and 14 with distant metastases. After successful treatment, thyroglobulin fell to unmeasurable levels in the four patients with local metastases and in four of six patients with distant metastases. In some patients treated successfully with 131I, the thyroglobulin level remained elevated for several months before falling to within the normal range. Thyroglobulin levels correlated with tumor growth in six of eight patients with tumor progression, remained high with a slight downward trend in one patient, and declined to unmeasurable levels in another case. Only one patient in this group showed radioiodine uptake in the metastases at the end of the observation period. The lack of 131I uptake in the other patients probably reflects the low degree of differentiation of the metastases. The following conclusions regarding the use of thyroglobulin measurement for the long-term follow-up of thyroid carcinoma can be made: (1) Following 131I therapy for metastatic thyroid carcinoma, return of thyroglobulin levels to within the normal range may take several months. The trend observed in serial thyroglobulin determinations is more meaningful than the absolute values for evaluating the success of therapy. (2) Thyroglobulin levels correlate with tumor growth in most cases of tumor progression, even when changes in differentiation may have led to a loss of radioiodine uptake by the metastases. It may be concluded that serial thyroglobulin determinations are therefore useful for the detection of metastases that do not accumulate radioiodine.

[Emission computed tomography of the left ventricle. Multiplanar ECG-triggered radionuclide ventriculography with a 7-pinhole collimator]. / Emissionscomputertomographie des linken Ventrikels. Multiplanare EKG-getriggerte Radionuklidventrikulographie mit dem 7-pinhole-Kollimator.

Tomographic studies and time-dependent tomograms on phantoms and patients were carried out using a 7-pinhole collimator in order to study the clinical value of ECG-triggered tomographic radionuclid ventriculography. A suitable computer programme has been developed. The results have shown that it is possible to evaluate local contraction abnormalities by this method. Using a left oblique position of the collimator (LAO [45 degrees]-cranial [15 degrees] ), emission computer tomography is aligned with the longitudinal axis of the heart. In this way, a single projection is sufficient to show the motility of the anterior and posterior walls and of the septum. Hypokinesis, akinesis or dyskinesis can be recognised visually. The localisation and extent of the defect can be determined through the 7-pinhole collimator. Reconstructed images of the triggered radionuclid scintigrams show excellent marginal definition. In the RAO projection, the left ventricle can be seen without superimposition and images obtained which equal those of a first-pass technique.

[Ankylosing spondylitis in women: comparison of scintigraphic results with clinical and roentgenologic findings]. / Die Spondylitis ankylosans beim weiblichen Geschlecht: Ein Vergleich szintigraphischer Ergebnisse mit klinischen und röntgenologischen Befunden.

Since ankylosing spondylitis (S.a.) tends to be milder and less progressive in women than in men, there are great difficulties in diagnosing S.a. in female patients. The role of scintiscanning for investigation of S.a. in women is discussed by few examiners only, especially there are no investigations of quantitative sacroiliac scintigraphy in large groups of female patients. Quantitative sacroiliac scintigraphy was performed in 19 female patients with S.a. and in 30 control subjects. The sacroiliac/sacrum ratio (Index ISG/sacrum) was calculated. Significantly increased uptakes were found in the patient group compared with the controls. Especially in the early periods of S.a. the activity index was highest. When history and physical examination lead to a suspicion of S.a. and there is no verification by roentgenographic studies, sacroiliac joint scintigraphy is indicated. If clinical and laboratory findings are respected in each patient, quantitative sacroiliac scintigraphy is useful for the early diagnosis of S.a. in female patients.

Optimizing renal DMSA-scintigraphy with 7-pinhole collimator.

Multiple pinhole emission tomographic imaging techniques are currently being applied to imaging of organs of a limited size. The purpose of this study was to evaluate the feasibility of this technique in kidney imaging with Tc99m-DMSA. A 7-pinhole collimator having 4.5 mm. pinhole apertures was used in conjunction with a widefield camera. Left and right kidney were imaged separately. Twelve small renal cysts with a diameter of 1 to 3.5 cm. verified by US or CAT were investigated by 7-pinhole and planar scintigraphy. Eight of 12 renal cysts were identified by 7-pinhole scintigraphy whereas only one cyst was seen by planar scintigraphy. The borderline of cysts detection was 1.5 cm. in 7-pinhole tomography. Basing on these comparative studies and experiences on many patient investigations it seems reasonable to perform renal scintigraphy with 7-pinhole tomography in a routine manner.

[Indications for oral TRH in a study of 998 patients (author's transl)]. / Zur Indikation des oralen TRH-Testes.

The authors determined values for T3, T4, T7, T3RIA and basal TSH, as well as TSH stimulation after intravenous administration of TRH in 998 patients. The test was negative in 259 patients (26%); in 51 of these patients (5.1%) no clinical or laboratory reasons could be found (low- or non-responders). In this group of patients the TRH test was repeated using a hundred times greater dose orally; in 27 cases (54%) of the low- or non-responders the oral test proved positive. In total, the TRH test was positive in 76.8%, negative in 20.9% and there were 2.3% non-responders. It was concluded that the oral test is more informative than the intravenous. Since the intravenous test gives poor results in only 5.1% of euthyroid patients, the extra effort appears hardly worth while. Further, failure of the intravenous TRH tests should lead to a repetition of the TRH test using oral application before a radioiodine test is done, since this will clarify more than half the tests with negative results.