Radioangioscintigraphy and Doppler echocardiography in the quantification of left-to-right shunt.

The magnitude of left-to-right shunt in 55 children with isolated congenital heart disease [atrial septal defect (ASD) or ventricular septal defect (VSD) (muscular and perimembranous)] was estimated by two methods: radionuclide quantification and Doppler echocardiography [flow (L/min) = mean velocity x area x ejection time x heart rate]. We found little difference between the magnitude of left-to-right shunt obtained with Doppler echocardiography and that with radioangioscintigraphy for a whole group of patients (N = 55, -11.42% to 12.04%) and for subgroups of ASD (n = 24, -12.49% to 12.19%) and VSD (n = 31, -10.69% to 12.23%). These results indicate that Doppler echocardiography, in comparison with radioangioscintigraphy, is sufficiently accurate for clinical estimation of the Q(p)/Q(s) ratio in isolated congenital heart disease with left-to-right shunt.

Radioiodine uptake in thyroid cancer patients after diagnostic application of low-dose 131I.

The aim of this study was to investigate the influence of the diagnostic administration of 74 MBq 131I on subsequent uptake of therapeutic radioiodine in thyroid cancer patients. Retention measurements were performed using a whole-body counter in 24 patients 6 weeks after total thyroidectomy. Profile scans were performed 2, 24, 48 and 72 h after the administration of the diagnostic dose and 72 h after the administration of the ablation-therapeutic dose (4.4 GBq). The mean ( +/- S.D.) effective half-life of the diagnostic dose in thyroid remnants was 40.3 +/- 23.0 h. The uptake in the thyroid remnants of the subsequent ablation dose 72 h after administration was 30.4 +/- 19.8% of that predicted from the diagnostic study. The greater reduction in uptake was associated with the longer half-life of iodine and higher uptake in the thyroid remnants at 24 h, with a longer interval between surgery and administration of the diagnostic dose and a shorter period between administration of the diagnostic and ablation doses. Our results show that a diagnostic dose of 74 MBq 131I markedly reduces thyroid uptake of an ablation dose of 131I. This should be taken into account during radiation dose planning whenever a quantitative dosimetric study is to be performed.

[Diagnostic approach in patients with kidney tumors]. / Racionalizacija dijagnostickih postupaka u bolesnika s tumorima bubrega.

The basic reason for the rationalization of diagnostic procedure is the cost benefit relation and making of the diagnostic course algorithms. On the basis of the Receiver Operating Characteristic (ROC) analysis of the diagnostic procedure (excretory urography, ultrasonography, computed tomography, digital subtraction angiography) the significance ranking has been established for certain kidney tumor diagnostic procedures. Angiography has been determined to be the most precise method, but the high degree of sensitivity (98%) and accurate diagnosis probability (98%), as well as noninvasiveness and relative inexpensiveness of ultrasonographic examination procedure, all argue for ultrasonography as the cornerstone, of renal tumor diagnosis. Using conditional probabilities and the Bayes analysis the advantage of the newly suggested over the standard diagnostic course has been calculated. The study has shown a significant decrease in the number of examinations: in 60 patients 16 excretory urographies, 10 computed tomographies, and 22 digital subtraction angiographies can be spared.

Brain shunts in patients with stroke: possible cerebral autoregulation of changed haemodynamics.

The cerebral perfusion was evaluated in 8 patients with stroke, caused by stenosis or occlusion of the carotid artery, and in 4 neurologically healthy subjects, using Tc99m labeled microspheres (LMS). By measuring activity in the brain and lungs after intracarotid injection of LMS, the existence of brain shunts in patients with stroke was demonstrated. It seems that brain ischaemia triggers the opening of shunts which appear to be one of the important autoregulatory and protective mechanisms to cerebral haemodynamic changes after brain infarction.

Dynamic scintigraphy of the oesophagus in the evaluation of reflux oesophagitis.

A method is presented which combines gastro-oesophageal reflux quantification and oesophageal transit measurement so as to differentiate true reflux from residual oesophageal activity. A group of 33 subjects with gastro-oesophagitis reflux symptoms and endoscopically confirmed reflux oesophagitis and a group of 21 asymptomatic subjects with normal oesophageal, gastric and duodenal endoscopic findings were examined. The subjects were given 37 MBq 99mTc-Sn-colloid in saline orally and then scintiscanned dynamically. The gastro-oesophageal quantification was done after transit measurement and after the oesophageal time activity (to detect residual oesophageal activity) reached its minimum. The difference in the reflux indices between the two groups was highly significant. In low-grade oesophagitis measured reflux was lower than in higher grades of disease. Only 4.7% false-positive results were observed with a specificity of 95%, indicating that this method may be superior to methods published earlier.

Haemodynamic changes in patients with subarachnoid haemorrhage assessed by Tc99m labeled albumin microspheres.

The aim of the present study was the investigation of haemodynamic changes in the brain in patients after subarachnoid haemorrhage (SAH) using Tc 99 m labelled albumin microspheres (LMS). Twenty-nine patients after SAH (13 in the acute and 16 in the chronic stage of the disease) and four neurologically healthy subjects were examined. LMS were injected in the carotid during angiography and brain and lung scintigrams were taken using gamma camera. In the control subjects a diffuse and uniform distribution of the activity in the brain was found. In the patients with acute SAH "patchy", nonhomogenous distribution of the activity was found, ranging up to the regional absence of perfusion. This pattern was observed in the chronic stage as well, but less obvious than in the acute. In all the patients the evident trapping of LMS in the lungs was demonstrated confirming brain shunts, absent in the control group. By measuring the activity in the brain and lungs after intracarotid injection of LMS, haemodynamic changes in the patients after SAH were proved and the existence of brain shunts was demonstrated. It seems that shunts are functional anastomoses and important protective mechanism, opening when cerebral haemodynamics is altered.

Radiochemical purity of D,L-hexamethylpropylene amine oxime and analysis of urine-excreted HMPAO decomposition species.

The radiochemical purity of hexamethylproxypropylene amine oxime (HMPAO) was determined in 16 preparations using the three-strip method. Immediately post-formulation, 90.3% +/- 4.0% (mean +/- SD) of the activity was associated with the primary lipophilic complex having an Rf of 0.45 +/- 0.11. We recorded a significantly higher content of sodium pertechnetate Tc 99m in methylethyl ketone (MEK) (21.1% +/- 8.5%) than in saline (5.0% +/- 3.7%; P less than 0.001). To clarify this finding, we ran sequential chromatograms (t = 0, 1, 2, 3 h) and found that the primary complex steadily disappeared, with a rate constant of 0.31 h-1. These results suggest that there is a decomposition of the primary complex during chromatography in MEK that might be responsible for the larger fraction of sodium pertechnetate Tc 99m in MEK. Eluate composition might influence the Rf of the lipophilic complex and the rate of its in vitro decomposition. In another experimental setting, we investigated 99mTc-HMPAO decomposition species in urine after application of a suspension of labelled leukocytes by performing sequential chromatographic analyses in 11 patients. At 1 h after application, urinary activity reflected the presence of a secondary complex (84.8% +/- 9.2%) and sodium pertechnetate Tc 99m (15.2% +/- 9.2%). The values after 3 h were markedly different (91.4% +/- 4.8% and 8.6% +/- 4.8%; P less than 0.001). Thus, urinary activity mostly consisted of a secondary complex, increasing with time.

Acute effect of electroconvulsive therapy on brain perfusion assessed by Tc99m-hexamethylpropyleneamineoxim and single photon emission computed tomography.

Regional cerebral blood flow (rCBF) was measured in relative terms with Tc99m-hexamethylpropyleneamineoxim and single photon emission computed tomography in 11 patients undergoing electroconvulsive therapy (ECT). The patients suffered from major depressive disorder (n = 8) or schizoaffective disorders (n = 3). rCBF was measured under general anesthesia 3 days prior to the ECT treatment and coinciding with the ECT stimulation. ECT caused a redistribution of the tracers uptake. The uptake became more pronounced in frontal parts of the brain and in the basal ganglia than in posterior parts of the cortex, and the thalamus. This selective effect of ECT on rCBF may be related to catecholaminergic projections to anterior parts of the brain.

[Evaluation of disorders of portal and total hepatic blood flow in patients with chronic diffuse liver diseases]. / Procjenjivanje poremecaja portalnog i ukupnog hepatalnog protoka krvi u bolesnika s kronicnom difuznom bolescu jetre.

The total hepatic blood flow measured with radioactive colloidal gold and the portal blood flow with the echo-Doppler method were investigated in 19 healthy examinees and 63 patients with chronic diffuse liver diseases. In the group of healthy examinees, the average values of the total hepatic blood flow was 1254 +/- 231 ml/min and of the portal one 1104 +/- 227 ml/min. The lowest blood flow values were obtained in patients with decompensated cirrhosis, especially in the hepatic (704 +/- 186 ml/min) and the portal blood flow (562 +/- 198 ml/min). In all the groups of examinees, registered values of the total hepatic blood flow were significantly higher than the values of the portal blood flow. The relations of the values obtained by both methods, among groups, were similar. By both methods decreased values are not obtained in liver steatosis and chronic persistent hepatitis in relation to the normal values. In patients with more serious forms of chronic diffuse liver diseases (cirrhosis and chronic active hepatitis) significantly lower blood flow values than the normal ones were obtained. Both methods contribute to the investigation of liver circulation disturbances, liver function damages, and to the follow-up of the liver disease course. The possibility of an indirect evaluation of the arterial hepatic blood flow from the difference of hepatic and portal blood flows may mean a new approach to the investigation of pathophysiological liver occurrences.