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At least 865 records · Page 48Linked to original sources
PubMed1993

Differentiation of single solid lesions in the lungs by means of single-photon emission tomography with technetium-99m methoxyisobutylisonitrile.

The value of technetium-99m methoxyisobutylisonitrile (MIBI) single-photon emission tomography (SPET) of the chest in differentiating lung carcinomas of various histological types and benign lesions was assessed in 54 patients (47 males and 7 females aged 19-77 years) with single solid lung masses. Chest radiography had indicated that 46 of the lesions were malignant (8 small cell carcinomas, 14 epidermoid carcinomas, 18 adenocarcinomas and 6 undifferentiated large cell carcinomas) and eight, benign. Ten, volunteers who also agreed to undergo 99mTc-MIBI SPET of the chest served as a control group. The results showed that only 65% (30/46) of the lung malignancies were detected by 99mTc-MIBI SPECT, including 63% (5/8) of the small cell carcinomas, 64% (9/14) of the epidermoid carcinomas, 72% (13/18) of the adenocarcinomas and 50% (3/6) of the undifferentiated large cell carcinomas. However, 75% (6/8) of the benign lesions were also detected. The diagnostic sensitivity, specificity and accuracy in differentiating malignant and benign lesions were 65%, 57% and 70%, respectively. We conclude that 99mTc-MIBI is of limited use in the differentiation of single solid lesions in the lungs.

Adenocarcinoma↗
PubMed1993

Resting technetium-99m methoxyisobutylisonitrile cardiac imaging in chronic coronary artery disease: comparison with rest-redistribution thallium-201 scintigraphy.

We studied 19 patients with angiographically proven coronary artery disease and left ventricular dysfunction (ejection fraction 33% +/- 8%) by resting technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) and rest-redistribution thallium-201 cardiac imaging. Thallium and 99mTc-MIBI studies were visually analysed. Of 285 segments, 203 (71%) had normal thallium uptake, 48 (17%) showed reversible thallium defects and 34 (12%) showed irreversible thallium defects. Of these 34 irreversible thallium defects, 19 (56%) were moderate and 15 (44%) were severe. Of the corresponding 285 segments, 200 (70%) had normal 99mTc-MIBI uptake, while 37 (13%) showed moderate and 48 (17%) showed severe reduction of 99mTc-MIBI uptake. Myocardial segmental agreement for regional uptake score between initial thallium and resting 99mTc-MIBI images was 90% (kappa = 0.78). Segmental agreement between delayed thallium and resting 99mTc-MIBI images was 77% (kappa = 0.44). In particular, in 26 (9%) segments 99mTc-MIBI uptake was severely reduced while delayed thallium uptake was normal or only moderately reduced. These data suggest that although rest-redistribution thallium and resting 99mTc-MIBI cardiac imaging provide concordant results in the majority of myocardial segments, some segments with severely reduced resting 99mTc-MIBI uptake may contain viable but hypoperfused myocardium. Thus, conclusions on myocardial viability based on 99mTc-MIBI uptake should be made with caution in chronic coronary artery disease.

Adult↗
PubMed1994

The use of technetium-99m methoxyisobutylisonitrile breast scintigraphy to evaluate palpable breast masses.

Thirty-eight female patients (age range: 31-79 years) with breast masses underwent technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) breast scintigraphy in order to assess the value of this technique in the detection of breast carcinomas and in their differentiation from benign breast masses. The results showed that 27 of the 32 cases of breast carcinoma were detected by 99mTc-MIBI breast scintigraphy. In contrast, none of the six benign lesions could be detected by this method. The diagnostic sensitivity, specificity and accuracy were 84%, 100% and 87%, respectively, in the differentiation of malignant and benign breast masses. In conclusion, we consider 99mTc-MIBI breast scintigraphy is useful in distinguishing malignancies from benign breast masses.

Adenocarcinoma↗
PubMed1994

Time course of technetium-99m sestamibi myocardial distribution in dogs with a permanent or transient coronary occlusion.

The influence of duration of coronary occlusion and reperfusion on technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-sestamibi) myocardial redistribution between necrotic, salvaged and non-ischaemic myocardium was investigated in dogs submitted either to a 90-min or a 24-h permanent left descending coronary artery occlusion (groups 1 and 2) or to a 90-min occlusion followed by 30 min, 6 h or 22.5 h of reperfusion (groups 3, 4 and 5). In all groups, 99mTc-sestamibi and radiolabelled microspheres were injected at 45 min of occlusion. After delimiting the area at risk and the infarct by Evans blue perfusion and triphenyltetrazolium chloride staining, radioactivity of heart slices from normal, viable-ischaemic and necrotic myocardium was measured in a gamma counter. A significant (P < 0.001) linear relationship between 99mTc-sestamibi distribution and myocardial blood flow was observed in the area at risk of groups 1 (r = 0.92), 2 (r = 0.84), 3 (r = 0.90), 4 (r = 0.93) and 5 (r = 0.58). In all groups, the mean percentage of 99mTc-sestamibi uptake in the ischaemic over normal zone overestimated significantly (P < 0.05) the mean percentage of the ratio in myocardial blood flow measured with microspheres (group 1: 13.3 +/- 1.4 vs. 7.7 +/- 1.2; group 2: 15.9 +/- 2.0 vs 5.6 +/- 1.2; group 3: 14.9 +/- 1.6 vs 6.2 +/- 1.0; group 4: 20.9 +/- 1.7 vs 10.9 +/- 1.8; group 5: 51.0 +/- 2.7 vs 14.0 +/- 2.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Parameters influencing SPET regional brain uptake of technetium-99m hexamethylpropylene amine oxine measured by calibrated point sources as an external standard.

Using calibrated point sources as an external standard to convert single-photon emission tomography (SPET) brain counts into absolute values of regional brain uptake (rBU) of technetium-99m hexamethylpropylene amine oxime (HMPAO), the relative contribution of different parameters to interindividual variability of cerebellar rBU was examined in 33 healthy volunteers. Stepwise regression analysis identified body surface as the most important factor underlying interindividual variability (P < 0.001), when compared with brain volume. In the normal volunteer population presented, age decrement of rBU corrected for body surface and brain volume equalled 60.5-0.20 x age. Based on the data of eight normal volunteers, including four test-retest studies with heart rate (HR) differences greater than 5 units and four test-stress studies with doubling of heart rate after bicycle exercise, influence of heart rate may be expressed by the equation delta rBU = 0.35 delta HR. Clinically, estimation of the relative influence of different factors allows normalization and extension of the applicability of the rBU quantification method used from longitudinal studies to group comparisons. Interestingly, results of the Daily Stress Inventory Scale and a subjective rating scale suggest the absence of a significant influence of minor stress on rBU. When using one vial per patient, chromatography may be omitted in clinical routine practice and lipophilicity may be estimated as 90% of the injected dose, if administered within 10 min after preparation. Finally, sensitivity of the quantification method was tested in eight volunteers using acetazolamide brain activation and showed a mean increase in cerebellar rBU of 30.2%, varying between 14.1% and 75.9%.

Acetazolamide↗
PubMed1994

Technetium-99m methoxyisobutylisonitrile localizes an ectopic ACTH-producing tumour: case report and review of the literature.

Extensive investigation including whole-body examinations with computed tomography and magnetic resonance imaging did not detect the suspected ectopic ACTH-producing tumour in a patient with advanced Cushing's syndrome and hypokalemic alkalosis. Gamma camera examination with technetium-99m methoxyisobutylisonitrile (MIBI) depicted the tumour, which was localized in the anterior neck and mediastinum. This was later verified by surgery. 99mTc-MIBI is normally used for myocardial scintigraphy. Its accumulation is unspecific and merely reflects metabolic activity. Despite this, the present case shows that examination with this agent can provide important information with regard to tumour localization in a given situation, thereby serving as a complement to other imaging modalities. The current literature on 99mTc-MIBI for tumour diagnosis is reviewed.

ACTH Syndrome, Ectopic↗
PubMed1992

A quantitative approach to technetium-99m hexamethylpropylene amine oxime.

A non-invasive, simple method for the quantitative evaluation of brain perfusion is presented using intravenous radionuclide angiography with technetium-99m hexamethylpropylene amine oxime (99mTc-HM-PAO). Graphical analysis was employed for the evaluation of the unidirectional influx constant (ku) of the tracer from the blood to the brain. The ku values were standardized to provide objective and comparable values, brain perfusion indices (BPI), among studied subjects by setting the ratio of ROIbrain size to ROIaorta size at 10. The whole-brain BPI values for the normal control subjects showed a significant negative correlation with advancing age (r = -0.632, P = 0.0204, n = 13). The mean of the whole-brain BPI of 7.0 (SD = 1.4) in 20 patients with cerebrovascular disorders was significantly lower than that of 10.6 (SD = 1.5) in 13 normal control subjects. The BPI measurements showed only minimal intra- and interobserver variability. Changes of the ratio of ROIaorta size and ROIbrain size did not significantly influence the BPI values. Hemispherical BPI values in 19 subjects (n = 38) showed highly significant correlations with the hemispherical mean cerebral blood flow values obtained from Xenon-133 single photon emission tomography (SPET) (r = 0.926, P = 0.0001 for the early picture method and r = 0.932, P = 0.0001 for the sequential picture method). This technique is easy to apply as an adjunct to SPET and may be helpful in the quantitative evaluation of brain perfusion in routine clinical studies.

Adult↗
PubMed1992

A partial defect in technetium-99m pyrophosphate image suggesting cardiac rupture following acute myocardial infarction.

We present the case of a 70-year-old woman with acute myocardial infarction who died of cardiac rupture on the 2nd hospital day. Dual isotope single photon emission computed tomography (SPECT) using thallium-201 chloride and technetium-99m pyrophosphate (PYP) performed on the 2nd hospital day showed a large perfusion defect in the anteroseptal wall on 201Tl image and a increased accumulation on 99mTc-PYP image in the anterior area consistent with a partial defect. Autopsy performed 1 h after death revealed a tear in the left ventricular anterior wall consistent with the defect on the 99mTc-PYP image. We propose that the finding of a partial defect in 99mTc-PYP is an interesting finding which may be associated with cardiac rupture following acute myocardial infarction.

Aged↗
PubMed1992

Abnormal uptake of technetium-99m hexakis-2-methoxyisobutylisonitrile in a primary cardiac lymphoma.

Abnormally high uptake of technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-SESTAMIBI) in the right ventricle and in the septum was observed in a 47-year-old woman initially presenting with dysarthria and left hemiparesis. Endomyocardial biopsy demonstrated a high-grade malignant non-Hodgkin's lymphoma. Complete remission was achieved by combined cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) chemotherapy and radiotherapy of the heart and mediastinum. The post-remission single photon emission tomography (SPET) 99mTc-SESTAMIBI study showed a homogeneous distribution pattern, in agreement with echocardiography computed tomography and magnetic resonance imaging. Increased uptake of 99mTc-SESTAMIBI, a myocardial perfusion agent, has been observed in some benign and malignant tumours. It may prove to be useful in the diagnosis and follow-up of malignancies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Influence of intravenously administered lidocaine on cerebral blood flow in a baboon model standardized under controlled general anaesthesia using single-photon emission tomography and technetium-99m hexamethylpropylene amine oxime.

The baboon under general anaesthesia as a model to assess drug-induced cerebral blood flow changes (delta CBF) using single-photon emission tomography (SPET) offers great in vivo possibilities but has to comply with demands on control of anaesthesia-related influencing factors, such as PaCO2 changes. The model sought in this study and described here allows control of PaCO2, in the baboon under thiopentone anaesthesia by ventilation, and was evaluated for the functional dependence of delta CBF vs delta PaCO2, using SPET technetium-99m hexamethylpropylene amine oxime (HMPAO) and the split-dose method together with controlled ventilation. During the experiment the model was validated for normal reactivity to PaCO2 changes, and subsequently applied to investigate the mechanisms (still uncertain) of CBF increase known to follow administration of the local anaesthetic lidocaine. Six baboons received 6 mg/kg lidocaine intravenously. CBF was measured between two consecutive SPET acquisitions (split-dose method) respectively relating to HM-PAO distributions in the brain before and after the injection of lidocaine. Meanwhile the animals were maintained at constant respiratory rate and volume. The results indicate that the correlation between delta CBF and the ensuing fall in PaCO2 deviated from the baseline pattern from the model and confirmed a cerebrovascular contribution to the lidocaine-induced CBF increase. This agreed well with mean and systolic blood pressure changes and heart rate.

Anesthesia, General↗
PubMed1991

Search for polynuclear pentavalent technetium complex of dimercaptosuccinic acid [Tc(V)-DMS] tumour localization mechanism. I. Medullary thyroid carcinoma animal model.

To search for the tumour localization mechanism of Tc(V)-DMS, a polynuclear pentavalent technetium complex of dimercaptosuccinic acid [Tc(V)-DMS], the development of medullary thyroid carcinoma (MTC) bearing mouse model was considered. Subcutaneously transplanted tumour was allowed to grow for 2, 4 and 6 weeks, and the influence of the tumour stage on the biodistribution of Tc(V)-DMS was screened. High radioactivity uptake in the tumour tissue was observed, and this accumulation showed a direct correlation with tumour growth and calcitonin secretion, the MTC marker detectable in the blood serum. The gathered data implicated some calcitonin-related factors as the mediator in the Tc(V)-DMS localization; participation of a phosphate-like oxoanion, TcO4(3-), is strongly suggested not only by the high radioactivity accumulation in the calcitonin-producing tumour but also by the accumulation in the bones of this model animal.

Animals↗
PubMed1991

Accumulation of leucocytes labelled with technetium-99m hexamethylpropylene amine oxime in malignant abdominal tumours.

A total of 343 leucocyte scans labelled with technetium-99m hexamethylpropylene amine oxime were reviewed that had been performed in 338 patients suspected of having abdominal infection or inflammation. There was uptake by malignant abdominal tumours in 10 cases (2.9%), which represents 62.5% of known malignancies at the time of the scintigram. Accumulation was seen in 8 patients with adenocarcinoma of the colon associated with a secondary infection in the tumour or pericolic inflammation. A large tumour that had spread beyond the bowel wall was related to a positive scintigram. Accumulation was also found twice in a malignant fibrous histiocytoma in which bleeding and an inflammatory reaction to necrosis were probably responsible for the uptake. The relevant treatment was delayed for 2 weeks-2 months in 4 patients with adenocarcinoma of the colon in whom the positive uptake was regarded as confirmation of the clinically suspected acute diverticulitis.

Abdominal Neoplasms↗
PubMed1991

Unexpected uptake of technetium 99m hexakis-2-methoxy-isobutylisonitrile in giant lymph node hyperplasia of the mediastinum (Castleman's disease).

The case of a patient with giant lymph node hyperplasia of the mediastinum who unexpectedly showed focal uptake of technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) is presented in this article. The patient was included in our research programme of tumor imaging with 99mTc-MIBI because the appearance of the mass on the chest radiogram and CT scan resembled a mediastinal tumour. Final diagnosis of giant lymph node hyperplasia was achieved through histopathological examination of the surgically removed lymph node.

Adult↗
PubMed1992

Evaluation of the renal excretion characteristics of technetium-99m mercaptoacetylglycyl-D-alanylglycine in healthy volunteers.

During a study of C-methyl derivatives of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) it was found that the isomer of 99mTc-mercaptoacetylglycyl-D-alanylglycine (99m-TC-MAGAG-DA) is superior to 99mTc-MAG3 with regard to its renal excretion characteristics in both mice and the baboon. We have now compared the renal handling of 99mTc-MAGAG-DA and 99mTc-MAG3 in 6 healthy volunteers in a paired study. Renograms of 99mTc-MAGAG-DA show a shorter time to renal maximum and a lower residual renal activity at 30 min post-injection (p.i.). The urinary excretion of 99mTc-MAGAG-DA is higher at both 30 and 60 min p.i. The plasma concentration of 99mTc-MAGAG-DA is lower than that of 99mTc-MAG3 at each moment up to 60 min p.i., and the plasma clearance is accordingly higher. It is concluded that 99mTc-MAGAG-DA is excreted more efficiently than 99mTc-MAG3, but the preparation of 99mTc-MAGAG-DA requires a HPLC purification step, and this limits its practical clinical usefulness.

Adult↗
PubMed1992

Technetium-99m hexamethylpropylene amine oxime single photon emission tomography in febrile convulsions.

We report our initial experience with technetium-99m hexamethyl propylene amine oxime (99mTC-HMPAO) brain single photon emission tomography (SPET) in the investigation of 19 children presenting with febrile convulsions. Two patients with complex febrile convulsions showed focal SPET lesions contralateral to the neurological deficit. However, in 9 out of 17 patients with simple febrile convulsions, focally disturbed perfusion was shown. In 4 out of 6 patients with electroencephalogram (EEG) abnormalities on admittance, SPET revealed at least 2 focal lesions. The temporofrontal region was the one most commonly involved. The SPET findings presented here also suggest a temporal relationship with the febrile convulsions, with markedly fewer lesions if examined after 12 days. In our initial experience, perfusion SPET did not show any particular pattern helpful in the differential diagnosis of the child presenting with febrile convulsions. Physiopathologically, our findings may support the hypothesis that brain tissue is regionally more vulnerable to fever, in patients presenting with febrile convulsions.

Brain↗
PubMed1992

Cortical perfusion response to an electrical stimulation of the auditory nerve in profoundly deaf patients: study with technetium-99m hexamethylpropylene amine oxime single photon emission tomography.

Brain activation procedures associated with single photon emission tomography (SPET) have recently been developed in healthy controls and diseased patients in order to help in their diagnosis and treatment. We investigated the effects of a promontory test (PT) on the cerebral distribution of technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) in 7 profoundly deaf patients, 6 PT+ and one PT-. The count variation in the temporal lobe was calculated on 6 coronal slices using the ratio (Rstimulation-Rdeprivation)/Rdeprivation where R = counts in the temporal lobe/whole-brain count. A count increase in the temporal lobe was observed in all patients and was higher in all patients with PT+ than in the patient with PT-. The problems of head positioning and resolution of the system were taken into account, and we considered that the maximal count increment was related to the auditory cortex response to the stimulus. Further clinical investigations with high-resolution systems have to be performed in order to validate this presurgery test in cochlear implant assessment.

Adult↗
PubMed1993

Technetium-99m labelled human serum albumin for ventriculography: a comparative evaluation of six labelling kits.

In this study we have compared the characteristics of six labelling kits for the preparation of technetium-99m labelled human serum albumin (99mTc-HSA) and evaluated the usefulness of the various 99mTc-HSA preparations as blood pool tracer agents. The amount of the principal ingredients, i.e. HSA and stannous ions, varies largely between the studied kits and this is probably a reason for the observed differences in the labelling rate. Analysis of the reaction mixtures after labelling of the respective kits with 99mTc showed in each preparation the presence of four to five radioactive components in variable relative amounts. The retention time of the main component on size-exclusion high-performance liquid chromatography (SEC-HPLC) was identical for all preparations. Biodistribution of the HPLC-isolated fractions was studied in mice. The components with the shortest and longest retention times on HPLC show poor retention in the plasma. The three intermediate fractions, including the principal peak, are initially retained relatively well in the blood (60%-70% of the injected dose after 10 min), but clearly to a lower degree than iodine-125 labelled HSA. Moreover, they diffuse out of the vascular compartment at a much higher rate than 125I-HSA. The biological behaviour of the main component of the various preparations was clearly different, despite the identical retention time on SEC-HPLC. Study of the total preparations in mice and a rabbit showed that two of them are cleared rapidly from the blood and cannot be considered valuable blood pool tracers. Diffusion of the other preparations out of the blood is slower but also considerable and compromises their use for ventriculography.

Animals↗
PubMed1993

Radioimmunoscintigraphy with technetium-99m-labelled monoclonal antibody, SM3, in gynaecological cancer.

Radioimmunoscintigraphy (RIS) with technetium-99m labelled SM3, a monoclonal antibody reacting with a polymorphic epithelial mucin glycoprotein core antigen, is evaluated. No adverse effects or thyroid uptake were observed. Studies in 45 patients (one twice) had a sensitivity for gynaecological malignancy of 100% (35/35) and a specificity of 73% (8/11), giving an overall accuracy of 93% (43/46). These results have led to the routine adoption of 99mTc RIS in the management of patients suspected of or having primary or recurrent gynaecological cancer.

Adult↗