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PubMed1990

Evaluation of children with possible appendicitis using technetium 99m leukocyte scan.

We evaluated the use of technetium 99m albumin colloid white blood cell (TAC-WBC) scan in 33 children with possible appendicitis. Ten children had appendicitis, four of whom had perforated their appendix at the time of surgery. Children with appendicitis differed from children without appendicitis in the incidence of right lower quadrant rebound tenderness (60% vs 17.4%), and white blood cell count (X10(3)/mm3) (14.0 + 1.9 vs 10.7 +/- 1.0). TAC-WBC scans were interpreted as either positive, negative, or indeterminate for appendiceal pathology. Twenty-five children had positive or negative scans for appendiceal pathology. There were 7 true positives, 2 false positives, 16 true negatives, and 0 false negatives. This resulted in a sensitivity of 100%, a specificity of 89%, an accuracy of 92%, a positive predictive value of 78%, and a negative predictive value of 100%. The TAC-WBC scan was indeterminate (abnormal but nondiagnostic for appendicitis) in eight children (24%), three of whom had appendicitis. The main values of TAC-WBC scan in our study of children with possible appendicitis were that it could be used emergently, it was abnormal in 100% of children with appendicitis, and it had a high negative predictive value (100%). The main limitation of TAC-WBC scan in our study was that it was indeterminate for appendiceal pathology in 24% of children. We recommend that TAC-WBC scan be used in children with possible appendicitis because it may allow outpatient management of up to 48%.

Adolescent↗
PubMed1990

Thallium-201 scintigraphy in bone sarcoma: comparison with gallium-67 and technetium-MDP in the evaluation of chemotherapeutic response.

This study attempts to characterize thallium-201 (201TI) uptake in patients with bone and soft-tissue sarcoma and to compare these findings with gallium-67 (67Ga) and bone scintigraphy with emphasis on evaluating tumor viability before and after chemotherapy. Thirty-eight patients with surgically-proven sarcomas were evaluated. All patients had gallium and thallium studies. Nineteen patients underwent pre- and post-chemotherapy thallium and evaluation. Seven patients also had technetium-99m-MDP (99mTc-MDP) bone scintigraphy comparisons. Pathologic changes pre- and postchemotherapy were graded on the basis of %tumor necrosis as defined histologically. Scintigraphic comparisons demonstrated a high degree of correlation with 201TI and poor correlation with 99mTc-MDP. Thallium-201 was superior to 99mTc-MDP and 67Ga in predicting tumor response to chemotherapy as determined by %tumor necrosis determined histologically. Gallium was superior to Tc-MDP in predicting response to chemotherapy. However, both 67Ga and 99mTc-MDP appear to be affected by factors other than tumor activity.

Adolescent↗
PubMed1990

Reduction-mediated technetium-99m labeling of monoclonal antibodies.

A simple and generally applicable method for labeling antibodies with technetium-99m (99mTc) is described. Following reduction of intrinsic disulphide bonds, the antibody is labeled with 99mTc in the presence of a weak competing ligand methylene diphosphonate. High labeling efficiencies (greater than 97%), in a final labeling step taking only a few minutes, can be routinely obtained with high in-vitro stability over 24 hr. No effect upon antibody reactivity is seen.

Animals↗
PubMed1990

Evaluation of vasospasm secondary to subarachnoid hemorrhage with technetium-99m-hexamethyl-propyleneamine oxime (HM-PAO) tomoscintigraphy.

Vasospasm of intracranial vessels is difficult to diagnose on clinical ground alone. Still, a clear diagnosis is important because it can impact on surgical timing; and also because it can help evaluate new treatments. Fifteen patients with sub-arachnoid hemorrhage secondary to aneurysm rupture were submitted to a total of 26 tomographic technetium-99m-hexamethyl-propyleneamine oxime (99mTc-HM-PAO) brain examinations that were correlated with temporally close (generally less than 24 hr) angiography or transmission computed tomography (TCT). Nine of 10 angiographically confirmed episodes of spasm and 6 of 6 infarcts seen on angiography or TCT were correctly diagnosed with 99mTc-HM-PAO. One normal scintigraphic exam was angiographically doubtful, one positive 99mTc-HM-PAO study was normal on angiography (sub-radiologic spasm?), one technically poor scintigraphy was positive for spasm on angiograms, and eight exams were normal for spasm with all modalities. We had agreement between tests in 23 of 26 series of exams (88%) obtained in 15 patients. We think that 99mTc-HM-PAO tomography should be useful for the evaluation of patients with suspected vasospasm.

Adult↗
PubMed1990

Cellular radiation dosimetry and its implications for estimation of radiation risks. Illustrative results with technetium 99m-labeled microspheres and macroaggregates.

Radiation absorbed doses at the cellular level were calculated for routine, human lung perfusion examinations after the intravenous injection of technetium 99m-labeled microspheres or macroaggregated albumin. In such studies, more than 90% of these particles are trapped in the precapillary arterioles of the lung, resulting in an extremely inhomogeneous distribution of radionuclide. We used a computer program that accounted for the inhomogeneity of radiopharmaceutical distribution and calculated the dose to individual lung cells. Absorbed doses to individual lung cells were found to vary by a factor of about 30,000. We believe that such findings call for a reevaluation of the justification for dosimetry at the organ level and an examination of the implications of absorbed doses calculated at the cellular level for the estimation of radiation risks.

Dose-Response Relationship, Radiation↗
PubMed1990

Effect of cyclosporin A on bile flow in experimental animals using technetium-99m EHIDA.

The effect of cyclosporin A (CyA) on bile flow was studied in experimental rabbits by radionuclide imaging and measurement of bilirubin levels. The rabbits were dosed intravenously with 15 mg/kg CyA for 4 consecutive days. Each rabbit served as its own control. The rabbits were injected IV with technetium (Tc)-99m EHIDA, and dynamic images were obtained prior to and 1, 4, 8, and 15 days after CyA treatment. There was no difference in half-times of blood clearance in control and CyA-treated rabbits. There were differences in the half-times of liver curve and bilirubin measurements between control and 4-day treated rabbits. By the 15th day after CyA treatment both the radionuclide findings and bilirubin levels became normal. The results suggest that CyA causes intrahepatic cholestasis and demonstrate evidence of reversibility of CyA's toxic effect on bile flow after treatment is discontinued.

Animals↗
PubMed1990

A comparison of the clinical relevance of thallium-201 and technetium-99m-methoxyisobutyl-isonitrile for the evaluation of myocardial blood flow.

Thallium-201 is at present the radiotracer of choice for the clinical evaluation of myocardial blood flow. Although different technetium-99m-isonitrile agents have been synthesised recently, only 99mTc-methoxyisobutyl-isonitrile (99mTc-MIBI) has proved to hold promise for clinical implementation. The myocardial distribution of 201Tl and 99mTc-MIBI was compared in a group of 20 patients, who underwent both 201Tl single photon emission computed tomography and 99mTc-MIBI study as well as coronary angiography. The sensitivity for predicting a lesion ranged from 25% to 88% in different areas of the heart and was comparable for the two radiopharmaceuticals. The specificity was greater than 80% for all regions except the inferior region where a specificity of 58% obtained by 99mTc-MIBI was better than the low specificity of 17% obtained with 201Tl (P less than 0.008).

Angiocardiography↗
PubMed1990

Peripheral arteriovenous malformation: diagnosis and localization by intraarterial injection of technetium-99m-MAA.

Radionuclide angiography with technetium-99m-labeled macroaggregates of albumin (99mTc-MAA), was successful in a single patient with a lower limb arteriovenous (AV) malformation, not only in diagnosis and quantitation of AV shunting, but also in localizing the site of shunting. This information proved useful to the angiographer, permitting a carefully tailored examination of the area of interest. This technique may hold promise as a preliminary examination in patients with limb AV malformations prior to angiography.

Adult↗
PubMed1990

The utility of technetium-99m DTPA inhalational scans in artificially ventilated patients.

Technetium-99m diethylenetriaminepentaacetic acid ([99mTc]DTPA) radioaerosol scans performed on 21 consecutive artificially ventilated patients were compared to 50 similar scans performed on patients breathing without mechanical assistance. All patients were referred for evaluation of suspected pulmonary embolism. The comparison revealed increased extrathoracic tracheal and mediastinal tracheal deposition but less central bronchial deposition in the artificially ventilated patients. Peripheral penetration in both groups of patients was excellent. Within the artificially ventilated group, peripheral penetration of activity seemed equally good in patients receiving positive-end expiratory pressure ventilation (n = 14) and those ventilated with normal pressures (n = 7). The frequency of regions in which aerosol activity (A) was present in the same zone as a perfusion (P) defect was the same in the controls and artificially ventilated patients (12% against 14%) but the frequency of the reverse type of mismatch (i.e., P greater than A) was significantly higher in the artificially ventilated group (42% against 14%, p less than 0.001). The results suggest that [99mTc]DTPA aerosol scans in artificially ventilated patients are associated with good peripheral penetration of activity and frequently yield valuable clinical information.

Aerosols↗
PubMed1975

Technetium 99m-pyridoxylideneglutamate: a new hepatobiliary radiopharmaceutical. I. Experimental aspects.

The labeling of pyridoxal and the pyridoxylidene derivative of glutamic acid with 99mTc has been achieved by a simple autoclaving procedure. Technetium-99-m-pyridoxylideneglutamate (99mTc-PG) shows marked biliary excretion with accumulation of radioactivity in the gallbladder and intestines of experimental animals. This compound has been extensively investigated with a view to its application in the diagnosis of biliary disorders in man by scintigraphy. Both scintigraphic and quantitative distribution studies showed that 99mTc-PG passed rapidly through the mouse liver with progressive accumulation in the gallbladder, allowing visualization of this organ within 10 min of injection. In 30 min over 40% of the injected dose was excreted into the intestine with an equivalent amount appearing in the urine; however, renal activity remained low. Scintigraphic studies in dogs showed results similar to those obtained in mice. Studies of the toxicity in three animal species indicated a wide margin of safety for 99mTc-PG in the dose proposed for diagnostic purposes in humans.

Animals↗
PubMed1989

[The use of technetium 99m with diethyleneamino pentaacetic acid (Tc 99-DTPA) in the pathology of the pyeloureteral junction].

By using diuretic renograms with technetium 99m-diethylenetriaminepentaacetic acid (Tc 99-DTPA) as a non-invasive procedure to evaluate paediatric patients with pelvicaliceal dilatation, we are able to make a clear differentiation between dilated, obstructed and non obstructed renal units. This procedure has given us a new insight into the management of these patients, permitting us to decide which patients would benefit from a surgical treatment and which patients would be reserved for clinical observation and follow up.

Adolescent↗
PubMed1989

[Myocardial perfusion during exercise and rest in coronary patients. Evaluation with a thallium 201 analog (isonitrile-technetium 99 m)].

Isonitrile-technetium, a Thallium 201 analog, was used for myocardial perfusion imaging in 12 patients with known coronary heart disease. 10-40 mCu of the isotope were injected at maximal effort during a Bruce stress test. Imaging was performed using 3 projections immediately after exercise and 24 hr later, using a gamma camera attached to a computer. Myocardial necrosis was detected with a sensitivity of 89% and specificity of 63%. Corresponding figures for stress induced ischemia were 89% and 100%. Accurate localization of ischemia or necrosis was obtained in 70% of all cases, improving to 100% in cases of total artery occlusion. These results, similar to those reported in the literature, encourage the use of Tc labeled isonitrile for myocardial perfusion imaging whenever Thallium 201 is difficult to obtain.

Adult↗
PubMed1989

Estimation of technetium-99m-MAG3 plasma clearance in adults from one or two blood samples.

Technetium-99m mercaptoacetyltriglycine (MAG3) clearance is strongly correlated with effective renal plasma flow and can be used directly as a measure of renal function. For these reasons, formulas were developed for estimation of [99mTc]MAG3 clearance based on one or two plasma samples. A two-exponential model provided an excellent fit for 8-point plasma clearance curves obtained from 35 patients having a wide range of renal function. The 8-point [99mTc]MAG3 clearance could be estimated from a single point at 43 min with an error of 19 ml/min (residual s.d.) or from two samples at 12 and 94 min with an error of 7 ml/min. The relative errors with MAG3 are thus comparable to those reported for similar techniques used with [131I]orthoiodohippurate, [99mTc]diethylenetriaminepentraacetic acid and [51Cr]ethylenediaminetetraacetic acid.

Adult↗
PubMed1989

The technetium-99m DTPA partition test in the diagnosis of tuberculous meningitis.

Although the blood/cerebrospinal fluid (CSF) bromide concentration ratio is sensitive and specific in the diagnosis of tuberculous meningitis (TBM), bromide-82 is not always available since it is not generally used in nuclear medicine. The use of technetium-99m diethylenetriamine penta-acetic acid (DTPA) for a partition test was compared with that of 82Br in 22 cases. Seven patients were diagnosed as having TBM, 9 patients had viral meningitis and 5 patients had septic meningitis. One normal control subject was also studied. Although the mechanism of transfer of substances across the blood-brain barrier as well as the factors affecting it are still unclear, both 82Br and 99mTc-DTPA cross the blood-brain barrier to a greater extent in TBM than in viral meningitis. Both tracers thus yield decreased serum/CSF concentration ratios in TBM. The accuracy of the 82Br partition test was found to be 90,9% if a critical serum/CSF ratio of 1,3 was chosen, compared with 86,9% for the 99mTc-DTPA partition test if a critical value of 3 was chosen. The use of 99mTc-DTPA offers various advantages, including general availability, lower cost and radiation dose per MBq, as well as the possibility of concomitant brain scintigraphy.

Adolescent↗
PubMed1989

[Does technetium scintigraphy in combination with gallium scintigraphy improve the differential diagnosis of aseptic and septic endoprosthesis loosening?].

In the majority of cases, 3-phase scintigraphy using Tc99m phosphate complexes is sufficient to diagnose a septic (infective) loosening of an endoprosthesis (hip or knee). Additional Ga 67 citrate scintigraphy should be considered only if technetium scintigraphy fails to supply an unequivocal finding. This is explained by the authors in detail.

Aged↗
PubMed1989

[Hepato-cholescintigraphy using technetium Tc 99m diethyl IDA in the follow-up of biliodigestive anastomoses].

The results of a study conducted on 24 patients given biliodigestive shunts are reported. Follow-up involved cholescintigraphy using 99m-IDA technetium. This examination provided valuable information about the morphodynamics of biliary flow and when the biliary peak and intestinal appearance times were lengthened, it was also able to identify significant obstructions. The technique is considered highly significant.

Aged↗
PubMed1989

[Quantification of the myocardial scar with technetium-99m-isonitrile (MIBI) in emission computerized tomography (SPECT)--comparison with serial creatine kinase determinations and radionuclide ventriculography].

Estimation of the size of myocardial infarction is of major interest for clinical patient management and a simple and reliable method is still searched for. In this study the potential of the new myocardial perfusion tracer, Technetium-99m (Tc-99m) methoxy-isobutyl-isonitril (MIBI) combined with emission computertomography (SPECT), is tested vs. the standard procedures of serial plasma creatine kinase (CK) measurements and radionuclide ventriculography (RNV). In 10 patients with first myocardial infarction, integral values for CK were obtained during the acute phase. Following three weeks of uncomplicated recovery the patient was referred for both types of myocardial imaging within four days. 370 MBq Tc-99m-MIBI were injected with the patient supine and at rest. One hour later SPECT acquisition commenced. The reconstructed slices were rearranged to long and short axes slices, which served to calculate a functional "scar image" in polar coordinates. The color-coded areas of significantly reduced tracer uptake were expressed in percent of the total myocardial area. RNV was performed with the patient supine and at rest, the left anterior oblique angle being optimized for septum visualization. Infarct localizations were antero-apical (three), anterolateral (two), postero-lateral (one), and posterior (four).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗