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PubMed1991

Evolution of technetium-99m-HMPAO SPECT and brain mapping in a patient presenting with echolalia and palilalia.

A 78-yr-old woman presented with transient echolalia and palilalia. She had suffered from Parkinson's disease for 2 yr. Routine laboratory examination showed hypotonic hyponatremia, but was otherwise unremarkable. Brain mapping revealed a bifrontal delta focus, more pronounced on the right. Single photon emission computed tomography (SPECT) of the brain with technetium-99m labeled d,l hexamethylpropylene-amine oxime (99mTc-HMPAO), performed during the acute episode showed relative frontoparietal hypoactivity. Brain mapping performed after disappearance of the echolalia and palilalia, which persisted only for 1 day, was normal. By contrast, SPECT findings persisted for more than 3 wk. Features of particular interest in the presented patient are the extensive defects seen on brain SPECT despite the absence of morphologic lesions, the congruent electrophysiologic changes and their temporal relationship with the clinical evolution.

Aged↗
PubMed1991

Technetium-99m-d,1-hexamethylpropyleneamine oxime (HMPAO) uptake and glutathione content in brain tumors.

Technetium-d, HMPAO SPECT was performed in 70 patients suffering from intracerebral tumors of various histologic types (glioma n = 30, meningioma n = 19, metastases n = 10, angioma n = 3, neuroma n = 2, lymphoma n = 2, neurocytoma n = 1, epidermoid n = 1, gliosis n = 1, cholesteatoma n = 1). Tumor classification was histologically verified in all subjects except in two cases with inoperable angiomas. SPECT was performed under resting state conditions with a dual-head rotating camera (SIEMENS ZLC 37) following intravenous injection of 18-25 mCi 99mTc-d, 1-HMPAO. Regional tracer deposit was expressed in terms of a cerebellar index (CBI). Significantly higher regional HMPAO uptake was found in meningiomas when compared with gliomas of different malignancy (ANOVA p less than 0.05). Within gliomas, regional uptake increased with malignancy (n.s.). In 23 patients, a total of 32 tumor specimens were obtained for histochemical analysis of glutathione (GSH) content using high-pressure liquid chromatography. A significant correlation (least square method, p less than 0.001) between CBIs and GSH values was found, supporting the hypothesis that GSH is the predominant factor for the conversion of the lipophilic complex to hydrophilic derivates.

Adult↗
PubMed1991

An analysis of cerebral blood flow in acute closed-head injury using technetium-99m-HMPAO SPECT and computed tomography.

Technetium-99m-hexamethylpropyleneamine (HMPAO) SPECT and x-ray CT were compared in 15 patients with acute closed-head injury. There were 44 focal lesions in all. Fifteen (34%) lesions were seen on both x-ray and SPECT. Seventeen (39%) lesions were seen only on SPECT. Twelve (27%) of the lesions were seen on x-ray tomography only. Of the lesions seen on x-ray tomography but not on SPECT, two were subarachnoid hemorrhage, two were thin subdural hematomas, and eight were contusions. This study shows that SPECT can detect focal disturbances of cerebral blood flow that are not seen on x-ray tomography. It also suggests that there are two types of contusions: those with a decreased cerebral blood flow (i.e., detectable on SPECT) and those with a cerebral blood flow equal to that of the surrounding brain.

Acute Disease↗
PubMed1977

Technetium pyrophosphate scanning in the detection of acute myocardial infarction: clinical experience.

Technetium-99m-stannous pyrophosphate (99mTc-PYP) accumulates in acutely infarcted myocardium and can be detected by scintiscanning. The clinical value of 99mTc-PYP scintiscanning was studied in 83 patients 6 hours to 21 days after the onset of acute chest pain. In 12 patients with normal electrocardiograms and serum enzyme values no uptake of 99mTc-PYP was detected on the scintigrams. Of 44 patients with electrocardiographic or enzyme evidence, or both, of acute myocardial infarction the scintigrams were positive in 31, "questionable" in 2 and negative in 11; no positive scan was obtained within 12 hours of the onset of pain, and the scans generally remained positive for up to 5 days. In 24 patients with evidence of prolonged myocardial ischemia the scans were positive in 2, questionable in 4 and negative in 18. The scans were negative in each of three patients with acute or constrictive pericarditis. Localization by electrocardiography and scintiscanning correlated nearly perfectly for transmural infarcts but subendocardial infarcts could not always be localized precisely by scintiscanning. The infarct area (total area of 99mTc-PYP uptake) correlated well with the peak serum value of creatine phosphokinase.

Angina Pectoris↗
PubMed1991

Enhancement by tetraphenylborate of technetium-99m-MIBI uptake kinetics and accumulation in cultured chick myocardial cells.

Myocellular uptake and retention of technetium-99m-hexakis (2-methoxyisobutylisonitrile) (Tc-MIBI), a lipophilic cationic myocardial perfusion and viability imaging agent, is dependent on both mitochondrial and plasma-membrane potentials. To test for enhancement of uptake kinetics by lipophilic anions, cultured chick heart cells were exposed to tetraphenylborate (TPB), which produced a concentration-dependent maximal 15-fold increase in Tc-MIBI uptake kinetics (at 3 x 10(-5) M) and enhanced peak accumulation of Tc-MIBI from 165.4 +/- 26.3 to 705.6 +/- 61.3 fmoles/mg protein.nMo (P less than 0.001). Carbonyl cyanide-m-chloro phenylhydrazone (CCCP; 10(-5) M), a mitochondrial uncoupler, rapidly depleted cellular content of Tc-MIBI in the presence of TPB (10(-5) M) from 300.0 +/- 30.0 to 42.5 +/- 1.9 fmole/mg protein.nMo (p less than 0.001). TPB enhanced both uptake rates and net accumulation of Tc-MIBI at all buffer Ko concentrations between 130 mM and 0.54 mM. Tc-MIBI influx rates allowed estimation of plasma-membrane potential as a function of Ko in the presence of valinomycin with a slope of -67 mV/decade (r = -0.99). The results further support a potential-dependent mechanism for cell uptake of Tc-MIBI and suggest a rational approach for increasing tissue extraction fraction in vivo.

Animals↗
PubMed1991

Local preparation, standardization and quality control of technetium labelled macroaggregated albumin for lung perfusion studies.

Lung perfusion study is an important investigation in various pulmonary diseases. The radiopharmaceutical commonly used now-a- days is imported macroaggregated human albumin (in kit form), which is labelled with technetium (Tc99m-MAA). Due to its high cost the technique could not be fully exploited. We have tried to locally prepare freeze dried MAA particles. Various parameters like concentration of protein, pH value, temperature, quality and quantity of reducing agents were studied to find out the optimum conditions for radiolabelling and the desired particle size. More than 98% of the added radioactivity was found tagged to the MAA particles in the final preparation (confirmed by paper chromatography). Labelled agent was found to be radiochemically stable for up to 6 hours. Initial animal and later human studies showed an ideal spectrum of particle size.

Chemistry, Pharmaceutical↗
PubMed1991

Sensitivity of technetium-99m-d,1-HMPAO to radiolysis in aqueous solutions.

The sensitivity of technetium-99m- (99mTc) d,l-HMPAO to radiolytically induced dissociation in aqueous solutions was investigated. It was found that cobalt-60 (60Co) gamma irradiation of solutions containing 99mTc-d,l-HMPAO with only 1600 cGy reduced the lipophilic chelates' radiochemical purity (RCP) to 50%-60%. The radiolytic sensitivity of 99mTc-meso-HMPAO is significantly lower. The results indicate that radiolytically produced intermediates limit the in vitro stability of 99mTc-d,l-HMPAO.

Cobalt Radioisotopes↗
PubMed1991

Visual stimulation increases technetium-99m-HMPAO distribution in human visual cortex.

The ability of changes in the distribution of technetium-99m-hexamethylpropylene amine oxime (99mTc-HMPAO) to reflect physiologic changes in regional cerebral blood flow (rCBF) was evaluated using photic stimulation, a procedure known to increase rCBF in the striate cortex. Seven healthy subjects were injected with 740 MBq 99mTc-HMPAO on two separate days. On one day, the injection was performed following closure of the eyes and patching for 5 min. On the other day, subjects were exposed to a stroboscopic light to produce photic simulation. Images of distribution of 99mTc-HMPAO were obtained using a Strichman 810X single-photon emission computed tomogram (SPECT) brain scanner. Comparison of images obtained during light occluded versus stimulation conditions revealed a significant increase in distribution of radiopharmaceutical in visual cortex relative to whole brain (peak increase corrected for radiopharmaceutical backdiffusion 36.7% +/- 6.6%). HMPAO appears to provide a useful method for detecting relative rCBF increases with SPECT.

Adult↗
PubMed1991

Technetium-99m-methylene diphosphonate (MDP) uptake in a sympathetic effusion: an index of malignancy and a review of the literature.

We report a patient with a sympathetic pleural effusion secondary to T-cell lymphoma that accumulated the bone imaging agent, Technetium-99m-methylene diphosphonate (99mTc-MDP). This case is significant in that malignant cells were not present on three cytologic examinations of the pleural fluid or multiple pleural biopsies. We also present a review of the published literature on pleural effusions that accumulate bone tracers. We conclude that pleural effusions that accumulate 99mTc-MDP should be considered malignant or secondary to a malignancy and further work-up is essential even if the cytologic exam of the pleural fluid is unremarkable.

Aged↗
PubMed1991

Delayed positive gastrointestinal bleeding studies with technetium-99m-red blood cells: utility of a second injection.

Two patients studied with technetium-99m-labeled red blood cells (RBCs) for gastrointestinal bleeding had positive findings only on 24-hr delayed images, at which time the site of bleeding could not be ascertained. In each instance, when additional delayed images suggested that active bleeding was occurring, a second aliquot of RBCs was labeled and injected. Sites of active hemorrhage were identified following further imaging in both patients. When delayed GI bleeding images are positive, further views should be obtained to ascertain if the pattern of intraluminal activity changes. If renewed active hemorrhage is suspected, reinjection with a second dose of labeled RBCs may identify the bleeding site.

Aged↗
PubMed1991

Technetium-99m-HMPAO brain SPECT in medically intractable temporal lobe epilepsy: a postoperative evaluation.

The aim of the present study was to evaluate the predictive value of interictal single-photon emission computed tomography (SPECT) using technetium-99m-labeled hexamethyl propyleneamine oxime (HMPAO) for the outcome after temporal lobectomy in patients with complex partial seizures. Out of 40 patients, 21 underwent right-sided and 19 left-sided temporal lobectomy. EEG and CT/MRI were primarily used to select the side of surgery. SPECT results correlated with temporal lobectomy in 68% of the patients. After surgical intervention, memory function was tested for both sides. Following left-sided temporal lobectomy, verbal memory was impaired in 8% of the patients, if SPECT agreed with the side selected for surgery, but in 83%, if it diverged from it. In the present study, there was no relationship between SPECT concordance with the side of temporal lobectomy and outcome as to seizure frequency and non-verbal memory. We conclude that preoperative interictal HMPAO/SPECT can contribute to the prediction of postoperative verbal memory function and that this method should be considered for use prior to temporal lobectomy.

Adolescent↗
PubMed1991

Differences in the intracellular processing of the radiolabel following the uptake of iodine-125- and technetium-99m-neogalactosyl albumin by the isolated perfused rat liver.

Neogalactosyl albumin (NGA) is a synthetic ligand to the asialoglycoprotein receptor (hepatic binding protein), which has been proposed as a useful receptor binding radiopharmaceutical for the noninvasive assessment of liver function. We have compared the uptake and intracellular processing of iodine-125- (125I) and technetium-99m- (99mTc) NGA following its administration as a 1-min pulse (147 pmol) to the isolated perfused rat liver. Approximately 40% of a pulse of either 125I- or 99mTc-NGA were taken up first pass by the liver. Of the 125I taken up by the liver, 82% was released after 15-20 min at the sinusoidal pole of the hepatocyte, predominantly as small molecular weight metabolites. A further 8% of the 125I-associated radioactivity was secreted as intact NGA into bile by the non-lysosomal (direct) pathway while 6% remained in the liver 1 hr after the pulse. In contrast, of the 99mTc taken up by the liver, only 4% reappeared in the perfusate while 40% was secreted into bile by the lysosomal (indirect) pathway and 55% remained in the liver 1 hr after the pulse. Since labeled metabolites of 99mTc-NGA do not appear in plasma, this permits kinetic modeling with 99mTc-NGA without correction for labeled metabolites. Thus, 99mTc-NGA is an excellent candidate as a receptor-binding radiopharmaceutical.

Albumins↗
PubMed1991

[Simultaneous assessment of wall motion and myocardial perfusion by technetium-99m methoxy isobutyl isonitrile].

The aim of this study was to assess whether or not myocardial uptake of Technetium-99m methoxy isobutyl isonitrile (Tc-MIBI) indicated myocardial viability. We performed simultaneous Tc-MIBI angiography and myocardial SPECT at rest on 12 patients with suspected coronary artery disease. Left ventricle was divided into 3 segments, and regional wall motion was graded as normal, hypokinesis and akinesis/dyskinesis. Myocardial uptake of Tc-MIBI was assessed as normal, reduced and absent in each segment. In segments with normal and reduced Tc-MIBI uptake, 7% (2 of 28) and 33% (2 of 6) showed wall motion abnormalities of akinesis/dyskinesis, respectively. However, all segments with absent Tc-MIBI uptake had asynergy of akinesis/dyskinesis (2 of 2, 100%). Myocardial Tc-MIBI uptake at rest indicated wall motion abnormalities and was considered to be useful for the evaluation of myocardial viability. First-pass radionuclide angiography followed by myocardial SPECT with Tc-MIBI demonstrated to be useful for the simultaneous assessment of the left ventricular wall motion and myocardial perfusion.

Coronary Circulation↗
PubMed1991

Chronic prosthetic vascular graft infection visualized with technetium-99m-hexamethylpropyleneamine oxime-labeled leukocytes.

Technetium-99m-HMPAO labeled leukocytes demonstrated chronic femoro-femoral prosthetic vascular graft infection several times during an 18-mo period in a 77-yr-old man. The intensity and distribution of the uptake in the graft were fluctuating in different imaging occasions possibly indicating the strength and location of the infection. Gallium-67-citrate imaging showed negative results twice. The reason for negative 67Ga results remained obscure. The infected graft was removed and the patient did well 5 mo postoperatively.

Aged↗
PubMed1991

Technetium-99m-MIBI and thallium-201 uptake in pulmonary actinomycosis.

A patient with pulmonary actinomycosis who unexpectedly showed focal uptake of technetium-99m-hexakis-2-methoxy isobutyl isonitrile and thallium-201 is presented. The appearance of the lesion on the chest radiograph and x-ray CT scan resembled a mediastinal tumor. The diagnosis of pulmonary actinomycosis was achieved by histopathologic examination of the surgically removed mass.

Actinomycosis↗
PubMed1990

Comparison of technetium-99m-HM-PAO leukocytes with indium-111-oxine leukocytes for localizing intraabdominal sepsis.

Technetium-99m-HM-PAO [( 99mTc]HM-PAO) leukocyte and indium-111-oxine (111In-oxine) leukocyte scanning were carried out simultaneously in 41 patients at 4 hr and 24 hr after reinjection to determine whether the 4-hr 99mTc scan could replace the 24-hr 111In scan for detecting intraabdominal sepsis. Abdominal infection was confirmed in 12 cases. The 4-hr 99Tc-leukocyte scan, the 4-hr 111In-leukocyte scan, and the 24-hr 111In-leukocyte scan yielded a sensitivity of 100%, 67%, and 100%, respectively, and a specificity of 62%, 90%, and 86%, respectively. The 24-hr 99mTc-leukocyte scan also produced a sensitivity of 100%, but it was falsely positive in all 29 cases without infection due to physiologic bowel uptake. False-positive 4-hr 99mTc-leukocyte scans were also produced by physiologic bowel uptake in seven cases all of whom had true-negative 4-hr and 24-hr 111In-leukocyte scans. Because of the high incidence of false-positive 4-hr [99mTc]HM-PAO leukocyte scans, it was concluded that they could not replace 24-hr 111In-leukocyte scans for detecting intraabdominal sepsis, and that serial 99mTc leukocyte scans starting earlier than 4 hr after reinjection must be evaluated.

Abdomen↗
PubMed1990

Regional cerebral blood flow imaging: a quantitative comparison of technetium-99m-HMPAO SPECT with C15O2 PET.

The aim of this study was to compare technetium-99m-hexamethylpropyleneamineoxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) with regional cerebral blood flow (rCBF) imaging using positron emission tomography (PET). As investigation of dementia is likely to be one of the main uses of routine rCBF imaging, 18 demented patients were imaged with both techniques. The PET data were compared quantitatively with three versions of the SPECT data. These were, first, data normalized to the SPECT cerebellar uptake, second, data linearly corrected using the PET cerebellar value and, finally, data Lassen corrected for washout from the high flow areas. Both the linearly-corrected (r = 0.81) and the Lassen-corrected (r = 0.79) HMPAO SPECT data showed good correlation with the PET rCBF data. The relationship between the normalized HMPAO SPECT data and the PET data was nonlinear. It is not yet possible to obtain rCBF values in absolute units from HMPAO SPECT without knowledge of the true rCBF in one reference region for each patient.

Aged↗