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PubMed2003

Characteristics of patients with abnormal stress technetium Tc 99m sestamibi SPECT studies without significant coronary artery diameter stenoses.

BACKGROUND: Single-photon emission computed tomography (SPECT) sestamibi (MIBI) is an excellent tool for detection of coronary artery disease (CAD), preoperative risk assessment, and follow-up management after coronary revascularization. While the sensitivity of MIBI SPECT for detecting CAD has been reported to exceed 90%, the specificity ranges between 53-100%. HYPOTHESIS: The study was undertaken to assess characteristics of patients with abnormal stress technetium Tc99m sestamibi SPECT (MIBI) studies without significant coronary artery diameter stenoses (< 50%). METHODS: Between January 1999 and November 2000, 270 consecutive patients were referred for coronary angiography due to reversible MIBI uptake defects during exercise. In 41 patients (15%; 39% women, mean age 59 +/- 9 years), reversible MIBI uptake defects were assessed although coronary angiography showed no significant CAD. These patients were compared with age- and gender-matched patients with perfusion abnormalities (39% women, mean age 60 +/- 9 years), due to significant CAD (coronary artery stenosis > 50%). RESULTS: There were no significant differences between the two groups regarding body mass index, left bundle-branch block (LBBB), or method of stress test (dipyridamole in patients with LBBB or physical inactivity [n = 11] and exercise in all the others [n = 30]). Left ventricular hypertrophy (44 vs. 23%, p = 0.05) and left anterior fascicular block (LAFB) (17 vs. 0%, p = 0.005) were more common in patients with perfusion abnormalities with no significant CAD, whereas ST-segment depression during exercise (17 vs. 37% p = 0.05) and angina during exercise (15 vs. 29%, p = 0.02) were significantly less common than in patients with abnormal MIBI perfusion studies and angiographically significant CAD. Sestamibi uptake defects during exercise were significantly smaller in patients without significant CAD than in matched controls with significant CAD (p < 0.0004). CONCLUSION: Of 270 consecutive patients, 41 (15%) referred to coronary angiography due to reversible MIBI uptake defects showed coronary artery stenoses < 50%. Twenty-six (10%) of these presented angiographically normal coronary arteries. The significantly higher proportion of left ventricular hypertrophy and LAFB in patients with reversible MIBI uptake defects without significant CAD suggest microvascular disease, angiographically underestimated CAD, and conduction abnormalities as underlying mechanisms.

Aged↗
PubMed2003

Additive value of low-dose dobutamine to technetium-99m sestamibi-gated single-photon emission computed tomography for prediction of wall motion improvement in patients undergoing coronary artery bypass graft.

BACKGROUND: The two most useful methods for myocardial viability assessment are perfusion imaging and dobutamine echocardiography. HYPOTHESIS: The present study investigated the additive value of a new method, dobutamine technetium 99m (99mTc)-sestamibi-gated single-photon emission computed tomography (SPECT), which combines these two modalities, to the prediction of wall motion improvement after revascularization. METHODS: Fifty-five consecutive patients with ischemic cardiomyopathy, who were referred for viability evaluation, underwent resting and dobutamine (dose, 5-10 microkg/kg/min) gated SPECT with 99mTc-sestamibi. Of these patients, 36 underwent coronary artery bypass graft (CABG) within 1 month of the study and 32 had repeat resting gated SPECT within 1 year. Global and regional wall motion, wall thickness, and perfusion were simultaneously analyzed at rest and after dobutamine using the 20-segment model; the sestamibi uptake and wall motion response to dobutamine of each segment were rated quantitatively. Based on these findings, the segments were categorized as normal, viable, or nonviable. The predictive values for wall motion improvement were assessed by perfusion, using cutoffs of 50 and 60% of sestamibi uptake, and thereafter by the addition of dobutamine response in the segments that were rated nonviable. RESULTS: Of the 1,080 myocardial segments studied, 906 (84%) had abnormal wall motion and were analyzed for viability. Concordance between perfusion and wall motion response to dobutamine was 60% with the 50% cutoff of sestamibi uptake, and increased to 65% with the 60% sestamibi cutoff (p < 0.04). The respective predictive values of wall motion improvement using the 50 and 60% cutoff points were as follows: sensitivity 93 and 70%, respectively, (p < 0.01); specificity 59 and 86% (p < 0.001), respectively; accuracy 77% for both. The addition of the wall motion response to dobutamine to the assessment of the nonviable segments by perfusion (60% cutoff) increased the sensitivity from 70 to 85% (p = 0.001) and the negative predictive value from 70 to 81% (p = 0.009); the positive predictive value remained high (86 vs. 82%). No additive value of wall motion response to dobutamine was demonstrated for nonviable segments by perfusion with a 50% cutoff. CONCLUSION: Dobutamine sestamibi-gated SPECT is a feasible method for the analysis of myocardial perfusion, function, and contractile reserve of individual myocardial segments in patients with ischemic cardiomyopathy. Viability assessment based on a threshold of 60% uptake of sestamibi, with the addition of the wall motion response to dobutamine in the nonviable segments, seems to yield better predictive values for wall motion improvement after CABG.

Aged↗
PubMed2002

Alpha-melanocyte-stimulating hormone peptide analogs labeled with technetium-99m and indium-111 for malignant melanoma targeting.

BACKGROUND: Previous studies have shown that the compact structure of a rhenium-cyclized alpha--melanocyte-stimulating hormone peptide analog, [Cys3410,D-Phe7]alpha-MSH(3--13), or Re-CCMSH, significantly enhanced its in vivo tumor uptake and retention. In this study, the metal chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was coupled to the N-terminus of Re-CCMSH in order to develop a melanoma-targeting peptide that could be labeled with a wider variety of imaging and therapeutic radionuclides. METHODS: Biodistribution properties of indium-111 ((111)In)--labeled DOTA-Re-CCMSH were compared with the non-DOTA-containing technetium-99m ((99m)Tc)--CCMSH in murine melanoma--bearing C57 mice to determine the effects of DOTA on tumor uptake and whole-body clearance. The tumor targeting capacity and clearance kinetics of (111)In-DOTA-Re-CCMSH were also compared with other related cyclic and linear (111)In-labeled DOTA-alpha-MSH complexes. RESULTS: The in vivo distribution data showed that the conjugation of DOTA to Re-CCMSH did not reduce its initial tumor uptake kinetics but did enhance its tumor retention and renal clearance properties. The tumor uptake of (111)In-DOTA-Re-CCMSH was significantly higher than the other (111)In-DOTA--coupled cyclic or linear alpha-MSH analogs used in this study. Moreover, (111)In-DOTA-Re-CCMSH displayed lower radioactivity accumulation in normal tissues of interest than its non-Re-cyclized counterpart, (111)In-DOTA-CCMSH; the disulfide bond--cyclized (111)In-DOTA-CMSH; or the linear (111)In-DOTA-NDP. CONCLUSIONS: Peptide cyclization via rhenium coordination significantly enhanced the tumor targeting and renal clearance properties of DOTA-Re-CCMSH, making it an excellent candidate for melanoma radiodetection and radiotherapy.

Animals↗
PubMed2002

Single tumor cell uptake and dosimetry of technetium-99m Fab' or minute anti-CD22 in low-grade B-cell lymphoma.

BACKGROUND: A patient with follicular lymphoma was investigated with 0.5 mg Fab' or minute anti-CD22 labeled with 1100 MBq technetium-99m ((99m)Tc). A computed tomography scan performed a week later revealed regression. This unexpected response prompted an investigation of single cell dosimetry of low-energy electron emitters. METHODS: Another patient with low-grade, unclassifiable B-cell lymphoma with a low expression of CD22 was injected with (99m)Tc anti-CD22. Blood samples were drawn 30 minutes, 4 hours, and 24 hours after injection. Lymphoma cells (CD19+) and T cells (CD3+), which served as control cells, were separated using a flow cytometer. The radioactivity of the two cell populations was measured in an NaI(Tl) well-type detector. The mean uptake per cell and absorbed dose were calculated. The CD22 expression of the patient's cells and of a B-cell lymphoma cell line (Raji) were assessed by flow cytometry for the extrapolation of the absorbed dose from the patient's cells to a cell line with higher CD22 expression. RESULTS: The average number of (99m)Tc atoms per CD19+ and CD3+ cell 4 hours postinjection were 5.4 and 0.054, respectively. Depending on the assumed ratio between antibody and CD22 molecules (1:2 or 1:1), the CD22 expression on the patient's cells and Raji cells varied from 2800 to 5700 and from 37,000 to 74,000 per cell, respectively. The average absorbed dose per cell ranged from 4 x 10(-7) to 0.1 grays (Gy). CONCLUSIONS: It seems feasible to assess the mean single tumor cell uptake of (99m)Tc targeted by Fab' or minute anti-CD22 in a patient's lymphoma using sorted cell populations, thereby allowing single cell dosimetry. Extrapolation of the absorbed dose from (99m)Tc to cells with higher CD22 expression was made and under certain conditions absorbed doses of 0.1 Gy were obtained, indicating the potential relevance of low-energy electron emitters to therapy.

Antigens, CD↗
PubMed2002

Detection of recurrent or persistent nasopharyngeal carcinomas after radiotherapy with technetium-99m methoxyisobutylisonitrile single photon emission computed tomography and computed tomography: comparison with 18-fluoro-2-deoxyglucose positron emission tomography.

BACKGROUND: The diagnostic accuracy of technetium-99m methoxyisobutylisonitrile (Tc-MIBI) single photon emission computed tomography (SPECT) and computed tomography (CT) of the head and neck for differentiating recurrent or residual nasopharyngeal carcinomas (NPC) from benign lesions after radiotherapy was compared with positron emission tomography (PET) with 18-fluoro-2-deoxyglucose (FDG). METHODS: Thirty six NPC patients underwent head and neck CT, Tc-MIBI SPECT, and FDG-PET four months after radiotherapy to differentiate recurrent or residual NPC from benign lesions. Histopathologic examinations of nasopharyngeal biopsies were performed for all 36 patients. No patients had multiple foci of NPC. RESULTS: Based on biopsy results, the sensitivity, specificity, and accuracy of CT for differentiating recurrent or residual NPC from benign lesions were 73%, 88%, and 83%, respectively. The sensitivity, specificity, and accuracy of Tc-MIBI SPECT were 73%, 96%, and 89%, respectively. The sensitivity, specificity, and accuracy of FDG-PET were 100%, 96%, and 97%, respectively. Combination CT and Tc-MIBI SPECT for 28 NPC patients with congruent results showed the same sensitivity, specificity, and accuracy of 100%, 96%, and 96%, respectively, as FDG-PET for differentiating recurrent or residual NPC from benign lesions. In eight patients with incongruent results between CT and Tc-MIBI SPECT, FDG-PET correctly differentiated two benign lesions and six recurrent or residual NPCs. CONCLUSIONS: In detecting recurrent or residual NPC, FDG-PET is the best tool. However, combined use of CT and Tc-MIBI SPECT can result in the same accuracy as FDG-PET.

Adolescent↗
PubMedDate not supplied

Comparative study of technetium-99m bone scans and orthopantomography in determining mandible invasion in intraoral squamous cell carcinoma.

The accuracy of preoperative assessment in determining invasion of the mandible by intraoral squamous cell carcinoma was analyzed in 48 patients who underwent mandibulectomy, and the results correlated with the histopathological reports of the resected specimens. Only 50% of the patients underwent the "ideal" surgery based primarily on clinical judgement, whereas 10 patients in the series were significantly undertreated. Clinical judgement and routine preoperative x-rays are accurate in cases where there is gross involvement of the mandible (17 of 19) but are significantly less successful in determining early bone invasion, invasion of the periosteum, or periosteal new bone formation. In such cases (26 of 48), a technetium-99m bone scan provides additional information. A grading system for reporting orthopantomographics (OPTs) and bone scans has been developed and utilized to form a reference grid to determine the optimum extent of mandibular surgery. The results show that using this protocol, unnecessary mandibular surgery may be reduced and inadequate surgical excision avoided.

Carcinoma, Squamous Cell↗
PubMed1986

Localization of technetium-99m methylene diphosphonate in bone using microautoradiography.

Technetium-99m methylene diphosphonate ([99mTc]MDP) is the most widely used bone-scanning agent today. In order to determine the precise bone locus of 99mTc corresponding to the delayed bone scan image, and to test the potential clinical use of this agent in enhancing the information obtained by bone scan, we employed [99mTc]MDP in this microautoradiographic study of normal bone and bone reparative tissue. Four white rabbits underwent operations in which two 1.5-mm drill holes were created in the subtrochanteric regions of both of their femora. An additional four white rabbits underwent sham operations of their femora, in which neither drilling nor periosteal injury occurred. Two rabbits were controls and did not undergo operation. After 7 days, the first two groups of rabbits were injected with [99mTc]MDP and bone scanned 2 h later. After the scans were completed, all three groups of animals were killed and their femora histologically processed for microautoradiography and routine histopathology. In the two groups that were injected with [99mTc]MDP, all bones showed the isotope to be clearly localized along mineralization fronts. The isotope was occasionally found in the substance of the osteoid, but was absent from the cytoplasm and nuclei of osteoblasts and osteocytes. Osteocytic lacunae showed the presence of isotope at their borders, but no identifiable pattern of isotope uptake was noted. Neither osteoclasts nor Howships lacunae showed isotope uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Characterisation via electrospray ionisation multistage mass spectrometry of three related series of nitrido technetium complexes containing phosphinothiolate and dithiocarbamate ligands.

Nine nitrido technetium compounds comprising bis-substituted Tc(N)(PS)(2) (1-4) (PS = bidentate phosphinothiolate ligands) and Tc(N)(dtc)(2) (5, 6) derivatives (dtc = bidentate dithiocarbamate), and mixed-ligand Tc(N)(PS)(dtc) (7-9) species, were subjected to electrospray ionisation mass spectrometry and MS(n) experiments. Bis-substituted phosphinothiolato complexes 1-4 lead to the straightforward formation of dinuclear species reasonably originating from proton bound dimers. These dinuclear species do not show, under collisionally induced fragmentation processes, the formation of monomeric units but cleavages related to the ligand framework, thereby proving the high stability of the [Tc--H(+)--Tc] bond. Bis-dithiocarbamate compounds 5 and 6 show, instead, abundant [M+H](+), [M+Na](+) and [2M+Na](+) ions, and their collisionally induced fragmentations are highly favoured with cleavages related to the C--N and C--S bonds. During these processes, the coordination of a water molecule to [MH-L](+) product ions is observed, as proved by the collisionally induced H(2)O loss detected for this species. Mixed-ligand compounds 7 and 8 show the protonated molecules and Na(+)-cationised ions with fragmentation processes related to the dithiocarbamate moiety. This behaviour indicates that coordination of ether- and ester-substituted dithiocarbamates to the [Tc [triple chemical bond] N] group is weaker than that of phosphinothiolates. Conversely, diethyldithiocarbamate inserted in mixed complex 9 enhances both C--N and Tc--S bonds, and fragmentation processes suggest that metal-phosphinothiolate and metal-dithiocarbamate show comparable strength.

Hydrolysis↗
PubMed1993

A novel [99m]technetium-labeled nitroheterocycle capable of identification of hypoxia in heart.

A novel [99m]technetium-labeled nitroimidazole was preferentially taken up and retained by hypoxic cardiac muscle. In rat hearts perfused with O2 or N2 equilibrated cell-free medium, uptake of the infused nitroheterocycle and its subsequent washout displayed biphasic kinetics. For both uptake and washout, the early phase was very rapid whereas the late phase was much slower. The amount of radioactivity retained after 40 min of clearance was about two-fold greater in hypoxic hearts than in normoxic hearts. Cardiac myocytes and mitochondria isolated from rat heart also accumulated the nitroheterocycle. Association of the compound with heart cells was inversely related to the level of available oxygen and was independent of intracellular energy level or mitochondrial redox state in the presence of oxygen. The results indicate that this [99mTc]labeled nitroimidazole may serve as a sensitive marker of hypoxic myocardium.

Animals↗
PubMed1992

Perfusion imaging of pancreas allografts using technetium-99m hexamethyl propylene amine oxime.

The vascular integrity and major changes in perfusion can be determined by visual interpretation of radionuclide flow studies. We studied the potential of a new radiopharmaceutical technetium-99m hexamethyl propylene amine oxime (99mTc-HMPAO) in the particular setting of pancreas transplantation. Perfusion was measured by perfusion indices (PI). Changes in graft perfusion were estimated by three independent observers. A predefined scale from 0 to 4 was used, with 0 representing no visualisation of the graft and 4 denoting sharp countour delineation and distinct demarcation from the background. In order to investigate the relation between perfusion of the pancreas graft and its exocrine function, we measured the amylase excretion rate (AER) in the urine, expressed in units per hour. It is concluded that 99mTc-HMPAO is a suitable radiopharmaceutical for pancreas allograft imaging. For the assessment of the vascular integrity in the direct postoperative period, the scintigram is very reliable. Although a correlation between exocrine function of the graft and the perfusion score was not established, it is possible to make a clear sorting of AER measurements into different groups.

Amylases↗
PubMed1992

Liver transplant rejection and cholestasis: comparison of technetium 99m-diisopropyl iminodiacetic acid hepatobiliary imaging with liver biopsy.

To determine whether the scintigraphic evaluation of technetium-99m diisopropyl iminodiacetic acid (DISIDA) uptake and excretion can distinguish among liver transplant patients with biopsy evidence for rejection, cholestasis or neither condition, we reviewed scintigrams and biopsies in 36 patients. There were 76 scintigrams with corresponding biopsies. Uptake and excretion were graded from image data on scales reflecting normal through severely abnormal values. Biopsies were evaluated for findings of cholestasis and rejection. The majority of scintigrams demonstrated normal uptake (60/75, 80%) and delayed excretion (65/76, 85%), which was most marked immediately after transplantation. One-way analysis of variance showed that the mean excretion values significantly differed between patients with normal biopsies and those with cholestasis and/or rejection (P = 0.0003). However, mean uptake scores demonstrated no statistically significant difference between these two groups of patients (P = 0.1). These findings suggest that 99mTc-DISIDA scintigraphy can differentiate between transplants with and without rejection/cholestasis but not between rejection and cholestasis. If 99mTc-DISIDA excretion is normal, rejection and cholestasis are unlikely.

Cholestasis↗
PubMed1992

Presurgical identification of hibernating myocardium by combined use of technetium-99m hexakis 2-methoxyisobutylisonitrile single photon emission tomography and fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography in patients with coronary artery disease.

We tested the possibility of identifying areas of hibernating myocardium by the combined assessment of perfusion and metabolism using single photon emission tomography (SPET) with technetium-99m hexakis 2-methoxyisobutylisonitrile (99mTc-MIBI) and positron emission tomography (PET) with fluorine-18 fluoro-2-deoxy-D-glucose (18F-FDG). Segmental wall motion, perfusion and 18F-FDG uptake were scored in 5 segments in 14 patients with coronary artery disease (CAD), for a total number of 70 segments. Each subject underwent the following studies prior to and following coronary artery bypass grafting (CABG): first-pass radionuclide angiography, electrocardiography gated planar perfusion scintigraphy and SPET perfusion scintigraphy with 99mTc-MIBI and, after 16 h fasting, 18F-FDG/PET metabolic scintigraphy. Wall motion impairment was either decreased or completely reversed by CABG in 95% of the asynergic segments which exhibited 18F-FDG uptake, whereas it was unmodified in 80% of the asynergic segments with no 18F-FDG uptake. A stepwise multiple logistic analysis was carried out on the asynergic segments to estimate the postoperative probability of wall motion improvement on the basis of the preoperative regional perfusion and metabolic scores. The segments with the highest probability (96%) of functional recovery from preoperative asynergy after revascularization were those with a marked 18F-FDG uptake prior to CABG. High probabilities of functional recovery were also estimated for the segments presenting with moderate and low 18F-FDG uptake (92% and 79%, respectively). A low probability of functional recovery (13%) was estimated in the segments with no 18F-FDG uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1992

Evaluation of myocardial viability with technetium-99m hexakis-2-methoxyisobutyl isonitrile and iodine-123 phenylpentadecanoic acid and single photon emission tomography.

The detection of viable myocardium in infarcted regions, i.e. hibernating myocardium, is a major goal in clinical cardiology today. We applied combined planar and single photon emission tomography (SPET) to the non-invasive estimation of the left ventricular ejection fraction (LVEF), myocardial blood flow and free fatty acid uptake in the heart. Of the 31 patients with coronary artery disease, 25 (81%) had had a previous myocardial infarction. All patients had at least one persistent perfusion defect on the stress-rest technetium-99m hexakis-2-methoxyisobutyl isonitrile (Sestamibi) study, and the results revealed 57/124 (46%) persistent perfusion defects. As a part of the perfusion study, the LVEF was measured at rest using the first-pass 99mTc-Sestamibi injection, and the mean LVEF was 47% +/- 9% (mean +/- 1 standard deviation). Iodine-123 phenylpentadecanoic acid (123I-pPPA) imaging at rest was performed within 2 weeks from the perfusion study. Then 6-mm transaxial, sagittal and coronal slices of the perfusion and 123I-pPPA studies were reconstructed. The bull's eye displays of the coronal slices were visually surveyed and divided into 4 quadrants: anterior, lateral, posterior and septal. The following image score was used: 0 = fixed defect, 1 = partial uptake and 2 = normal uptake. Moreover an index of metabolic reserve (MR) was calculated by dividing the bull's eye of the 123I-pPPA study by the bull's eye of resting 99mTc-Sestamibi, and its maximum value was normalized to 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty Acids↗
PubMed1993

Bleomycin lung toxicity detected by technetium-99m diethylene triamine penta-acetic acid aerosol scintigraphy.

In this study we investigated bleomycin-induced pulmonary toxicity in patients with germ-cell tumour by means of technetium-99m diethylene triamine penta-acetic acid aerosol scintigraphy. Twenty untreated patients who had no clinical or radiological evidence of pulmonary disease received four courses of etoposide, cisplatin and bleomycin chemotherapy. Aerosol lung scintigraphy and pulmonary function tests were performed in all patients before bleomycin treatment and after administration of 180 and 360 mg bleomycin. On the basis of the scintigrams the percentage decline in activity per minute (Kep) was evaluated, which represented an accurate parameter of lung membrane permeability. Pretreatment Kep values (0.891 +/- 0.286) were significantly lower than those obtained following 180 and 360 mg bleomycin treatment (1.176 +/- 0.336 and 1.389 +/- 0.477, respectively; P < 0.0005). The Kep values obtained with 180 and 360 mg bleomycin treatments were also significantly different (P < 0.005). In contrast, no significant change was observed in the results of pulmonary function tests. Our results demonstrate that evaluation of the pulmonary clearance of 99mTc-DTPA represents a useful means of monitoring the functional status of the lung epithelial membrane during bleomycin treatment. Further prospective studies are needed to assess the relationship between increase in permeability and development of lung toxicity in order to decide which patients should discontinue bleomycin therapy.

Adult↗
PubMed1993

A simple two-strip method to determine the radiochemical purity of technetium-99m mercaptoacetyltriglycine.

Technetium-99m mercaptoacetyltriglycine (MAG3) has been used extensively as a renal function agent for several years. Radioimpurities in the MAG3 kit preparation are not only concentrated and excreted in the kidneys. Therefore proper quality control for renal studies is even more important to make possible a rapid and adequate interpretation of diagnostic studies. The standard method to determine the radiochemical purity is high-performance liquid chromatography (HPLC), which is time consuming and expensive. We set up a new simple thin-layer chromatography (TLC) method based on instant thin-layer silica gel strips as stationary phase for checking the main impurities, free pertechnetate and reduced hydrolysed 99mTc-colloid. Comparison of TLC and HPLC results showed no significant differences (t-test, P < 0.05); the correlation between the results obtained with the two methods in respect of the free pertechnetate content was excellent (r = 0.99913). The TLC method was also efficient in determining the percentage of 99mTc-colloid. The main impurity found in 37 routine preparations was free pertechnetate; the mean radiochemical purity was 97.95%. The time required to perform the analysis was less than 20 min. The new TLC system is a cheap, simple, fast, reliable and accurate method for the quality control of the MAG3 kit preparation, and is especially suitable for routine use.

Chromatography, High Pressure Liquid↗
PubMed1993

Technetium-99m hexamethylpropylene amine oxime single photon emission tomography of the brain in early Parkinson's disease: correlation with dementia and lateralization.

Regional cerebral blood flow was assessed in 19 patients with early idiopathic Parkinson's disease (PD) and 12 control subjects of similar age by single-photon emission tomography using technetium-99m hexamethylpropylene amine oxime (HMPAO). Of the patients with PD, seven were mildly demented and 15 presented with hemiparkinsonism. Mean HMPAO cortical or basal ganglia/cerebellum activity ratios were calculated. Mean cortical and regional uptake ratios in non-demented PD patients were not significantly different from values in the controls. In contrast, besides generalized cortical hypoperfusion, demented PD patients had significantly lower HMPAO uptake in the frontal and basal ganglia regions than non-demented patients. These observations support the hypothesis of impaired neuronal activity in both cortical and subcortical regions of the brain in demented PD patients. In hemiparkinsonian patients, the only asymmetrical finding was a relative hypoperfusion in the contralateral parietal region. This may be due to deafferentation of the thalamoparietal pathways. The lack of asymmetrical uptake in basal ganglia in our PD patients may be explained by their staging at the time of the investigation (stage I and II, Hoehn and Yahr scale).

Aged↗
PubMed1993

Myocardial scintigraphy with thallium-201 and technetium-99m-hexakis-methoxyisobutylisonitrile in left bundle branch block: a study in patients with and without coronary artery disease.

In left bundle branch block (LBBB) thallium-201 myocardial scintigraphy frequently reveals septal abnormalities in the absence of coronary artery disease (CAD) and gives rise to "false-positive" results in patients with suspected CAD. It has not yet been clarified which pathophysiological mechanism is responsible for these perfusion abnormalities. A total of 66 patients with constant LBBB were investigated with 201Tl or technetium-99m-hexakis-methoxyisobutylisonitrile (MIBI), 62 underwent coronary angiography. Of 12 patients without left anterior descending artery (LAD) or right coronary artery (RCA) stenoses, 11 had a reversible septal activity deficit after 201Tl stress injection, whereas 20 of 22 patients without relevant CAD showed a constant stress/rest septal deficit using MIBI. Regarding patients with significant LAD and/or RCA stenoses, both radio-pharmaceuticals almost always showed a "reversible" septal deficit: with 201Tl in 15 of 16 individuals and with MIBI in 14 of 15. In 12 patients 201Tl was reinjected at rest. In those who had LAD or RCA stenoses (n = 5), early septal activity uptake after stress injection was poorer than that after rest injection; in the absence of CAD (n = 7), septal stress uptake corresponded with that of rest injection. It is concluded that septal perfusion abnormalities in LBBB and the absence of CAD are characterized by an exercise-independent reduction of septal blood flow per mass of viable myocardium and that stress/rest injection protocols of myocardial perfusion tracers are able to differentiate between LBBB with and without CAD.

Aged↗
PubMed1993

Determination of the technetium-99m mercaptoacetyltriglycine plasma clearance in children by means of a single blood sample: a multicentre study. The Paediatric Task Group of the EANM.

A multicentre European study was undertaken in order to determine a reasonable algorithm allowing the determination of overall technetium-99m mercaptoacetyltriglycine clearance using a single blood sample. Employing multiple blood sample clearance as a reference method, it was shown that an acceptable estimation of the MAG3 renal clearance could be obtained using a blood sample taken at any time between 30 and 40 min after tracer injection. After correction for body surface area, comparison of clearance determined using (a) the single blood sample and (b) the multiple blood samples provided a coefficient of correlation of 0.949 and an SEE of 27 ml/min. This algorithm is valid for clearance values higher than 100 ml/min/1.73 m2 and for children older than 1 year of age.

Algorithms↗