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At least 1,225 records · Page 68Linked to original sources
PubMed2004

Challenging the neuronal MIBG uptake by pharmacological intervention: effect of a single dose of oral amitriptyline on regional cardiac MIBG uptake.

PURPOSE: Imaging with metaiodobenzylguanidine (MIBG) is used for the assessment of neuronal dysfunction in various cardiovascular disorders. Although valuable information is obtained by resting MIBG imaging, it is conceivable that competitive interference with the re-uptake mechanism would exaggerate MIBG defects and might unmask subclinical neuronal dysfunction. Tricyclic antidepressants, such as amitriptyline, have been reported to significantly increase cardiac MIBG washout and inhibit uptake into presynaptic neurons. This study was undertaken to assess whether a single oral dose of amitriptyline could influence cardiac MIBG distribution. METHODS: Six patients (aged 62-81 years; four males, two females) who had demonstrated a normal cardiac MIBG scan during work-up for movement disorders were studied. The patients underwent a second 123I-MIBG study after oral administration of 25 mg amitriptyline within 1 week. Single-photon emission computed tomography images were acquired at 4 h to assess the regional distribution of MIBG, after generation of polar maps and employing a 20-segment model. Mean percentage of peak activity was calculated for each segment at rest and after amitriptyline administration. RESULTS: After amitriptyline administration, there was a decrease in regional MIBG uptake in 10+/-4 segments per patient [62/120 segments (52%): 37 segments with a 5-10% decrease, 25 segments with a >10% decrease]. This change was statistically significant in lateral (P=0.003), apical (P<0.0001) and inferior (P=0.03) regions. CONCLUSION: A single oral dose of amitriptyline can induce changes in the uptake and retention of cardiac MIBG, indicating the feasibility of use of pharmacological intervention in cardiac neurotransmission imaging.

3-Iodobenzylguanidine↗
PubMed1984

Critical analysis of the application of Bayes' theorem to sequential testing in the noninvasive diagnosis of coronary artery disease.

The utility of Bayes' theorem in the noninvasive diagnosis of coronary artery disease (CAD) was analyzed in 147 patients who underwent electrocardiographic stress testing, thallium-201 perfusion imaging and coronary angiography. Eighty-nine patients had typical anginal chest discomfort and 58 had atypical chest pain. Sensitivity and specificity of the tests and prevalence of CAD at each level of testing were tabulated and compared with the results generated from Bayes' theorem. The sensitivity of electrocardiographic stress was higher in patients with multivessel CAD than in patients with 1-vessel CAD. Sensitivity, but not specificity, of each test was dependent, in part, on the result of the other test. However, the probabilities calculated from Bayes' theorem when used for sequential testing are remarkably close to the tabulated data. Thus, Bayes' theorem is useful clinically despite some evidence of test dependence. Sequential test analysis by Bayes' theorem is most useful in establishing or ruling out a diagnosis when the pretest prevalence is approximately 50% and when the 2 tests are concordant.

Aged↗
PubMed2005

Preferred stereoselective brain uptake of d-serine--a modulator of glutamatergic neurotransmission.

Although it has long been presumed that d-amino acids are uncommon in mammalians, substantial amounts of free d-serine have been detected in the mammalian brain. d-Serine has been demonstrated to be an important modulator of glutamatergic neurotransmission and acts as an agonist at the strychnine-insensitive glycine site of N-methyl-d-aspartate receptors. The blood-to-brain transfer of d-serine is thought to be extremely low, and it is assumed that d-serine is generated by isomerization of l-serine in the brain. Stimulated by the observation of a preferred transport of the d-isomer of proline at the blood-brain barrier, we investigated the differential uptake of [3H]-d-serine and [3H]-l-serine in the rat brain 1 h after intravenous injection using quantitative autoradiography. Surprisingly, brain uptake of [3H]-d-serine was significantly higher than that of [3H]-l-serine, indicating a preferred transport of the d-enantiomer of serine at the blood-brain barrier. This finding indicates that exogenous d-serine may have a direct influence on glutamatergic neurotransmission and associated diseases.

Animals↗
PubMed1977

Scintiphotography of lungs with dry aerosol--generation and delivery system: concise communication.

A compressed-air nebulizer with low holdup and high output was used to nebulize [99mTc] pertechnetate presented in normal saline. Generated droplets were dried in line and led to an inhalation chamber from which the dry aerosol was inhaled using a nose or mouth inhalation unit. The mass median diameter of the particles was 0.8 microns, with an associated geometric standard deviation of 2.0. The deep lung delivery efficiency--defined as the ratio of the activity deposited in the lung area to the activity nebulized--was found to be reproducible and consistent (15-22%) in all the subjects studied. A 3-5 min inhalation of aerosol, nebulized from 20 mCi, was sufficient to provide a lung image of good information density. No noticeable deposit was seen in the trachea or major brochi. The system is inexpensive, stable in performance, adaptable to other solutions or colloids, and is promising for routine use.

Aerosols↗
PubMed1998

Myoelectric activity of the ileum, cecum, and right ventral colon, and cecal emptying of radiolabeled markers in clinically normal ponies.

OBJECTIVES: To determine normal cecal emptying curves for liquid- and solid-phase radiolabeled markers and to further define myoelectric patterns of the ileum, cecum, and colon in healthy ponies. ANIMALS: 6 adult ponies. PROCEDURE: A cecal cannula and 12 bipolar Ag-AgCl recording electrodes were sutured to the ileum, cecum, and right ventral colon of the ponies. Radioisotopes, indium 111-labeled diethyltriaminepentaacetic acid (111In-DTPA) and technetium 99m (99mTc)-labeled sulfur colloid bound to egg albumen, were introduced through the cannula directly into the cecal body. Movement of these markers from the cecum was monitored by a gamma camera, and power exponential clearance curves were generated. Myoelectric data were collected before and after i.v. administration of isotonic saline (0.9% NaCl) solution, and were analyzed for spike burst (SB) rate, relative activity index, and mean burst duration. Myoelectric complexes were identified from observation of chart recordings or compressed, digitized data. RESULTS: Clearance curves were generated for liquid (111In-DTPA)- and solid (99mTc)-phase markers. Marker types were not different with respect to lag phase, but liquid markers emptied at a slightly faster rate than did solids. Baseline values were calculated after saline solution administration for each of the myoelectric variables investigated. A relation between ileal, cecal, and colonic myoelectric activity was identified. Activity consistent with the previously described colonic migrating myoelectric complex in the pelvic flexure was identified in the right ventral colon. CONCLUSIONS AND CLINICAL RELEVANCE: Baseline data on normal cecal emptying was obtained; this technique could be used to evaluate the effect of postulated motility-modifying treatments used in equine practice.

Animals↗
PubMed1997

Detection of in vivo P-glycoprotein inhibition by PSC 833 using Tc-99m sestamibi.

Tc-99m sestamibi is a substrate of P-glycoprotein (Pgp) that has been proposed for use as a functional imaging agent for the multidrug resistance-1 phenotype. In vitro, retention of sestamibi by cells that overexpress Pgp can be modified by the presence of Pgp antagonists. In a Phase I trial of the Pgp reversal agent PSC 833, we show that the effects of this reversal agent can also be demonstrated in patients. Nine patients with metastatic renal carcinoma were studied three times: at baseline, approximately 1 day after vinblastine infusion, and while on PSC 833. One patient with metastatic adrenocortical cancer was also studied. Time activity curves and areas under the curve (AUCs) were obtained for tumor, liver, lung, and myocardium, and organ:heart AUC ratios were generated. With PSC 833, tumor visualization was enhanced, and statistically significant increases were found in AUC ratios for tumor and liver compared to baseline. For the liver, significant differences were also found between the vinblastine versus PSC 833 scans but not between the baseline versus vinblastine scans. This study demonstrates that sestamibi retention by tumor and liver is altered in the presence of the reversal agent PSC 833, presumably reflecting inhibition of Pgp. Thus, sestamibi may be useful in vivo as a means of monitoring the effects of this and other reversal agents on various tumors and normal tissues that express Pgp.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1985

Diagnostic imaging, a "parallel" discipline. Can current technology provide a reliable digital diagnostic radiology department?

Only recently has any detailed criticism been voiced about the practicalities of the introduction of generalised, digital, imaging complexes in diagnostic radiology. Although attendant technological problems are highlighted we argue that the fundamental causes of current difficulties are not in the generation but in the processing, filing and subsequent retrieval for display of digital image records. In the real world, looking at images is a parallel process of some complexity and so it is perhaps untimely to expect versatile handling of vast image data bases by existing computer hardware and software which, by their current nature, perform tasks serially. Successes in applying new imaging devices using digital technology, numerical methods and more easily available computing power are directing radiology towards the concept of all-digital departmental complexes. Hence a critical discussion of fundamental problems should be encouraged, to promote a thorough understanding of what may be involved (Gray et al, 1984) in following such a course. It is equally important to gain some perspective about the development possibilities for existing, commercially available equipment being offered to the medical community.

Computers↗
PubMed1991

Dynamic hepatic scintigraphy: the effect of using high administered activity on reproducibility of hepatic perfusion index value.

The hepatic perfusion index (HPI) may be of value in the detection of both overt and occult hepatic metastases in patients with colorectal carcinoma. Using the standard technique, the low counts obtained in each region of interest can produce statistical unreliability in the curve generation and render many studies unsuitable for analysis. In this study the effects of a high administered activity (400 MBq) on the inter- and intra-observer reproducibility of dynamic hepatic scintigraphy was investigated in 18 consecutive patients with colorectal cancer. All 18 patient studies were suitable for analysis by two observers. The correlation coefficient of measurements between observers was 0.98 (P less than 0.000 01 linear regression analysis), with a root mean square difference of replicate HPI measurements between observers of 0.045. The median range of HPI for four reprocessings by one observer was 0.035, with a maximum range of 0.11. Although high administered activity improves count statistics, for the individual patient study the activity used is not the major source of uncertainty in the derived HPI value.

Colorectal Neoplasms↗
PubMed1996

Slow bolus injection of ribose in the identification of thallium-201 redistribution following combined adenosine/dynamic exercise stress.

AIM: A simple stress/redistribution thallium-201 myocardial perfusion imaging protocol may underestimate the degree of thallium redistribution in a defect identified on the stress images. We sought to investigate whether a slow-bolus injection of D-ribose improves the identification of thallium redistribution following combined adenosine/dynamic exercise stress. MATERIALS AND METHODS: Fifteen patients (10 males, five female, median age 63 years, range 50-75) were enrolled in the study. All underwent two successive adenosine plus exercise myocardial perfusion scintigraphy protocols 7-14 days apart. Adenosine was infused at 140 micrograms.kg-1.min-1 coupled with 25 W ergometer pedalling for 6 min with 74 Mbq of thallium-201 being injected at 4 min. Immediately following the stress image acquisition, patients received the one of either 60 mg.kg-1 of D-ribose or normal saline, injected over 5 min. Redistribution images were acquired after 4 h. The identical stress procedure was conducted in the crossover arm of the study, and patients received the alternative test article. SPECT images were visually analysed and scored in a nine segment model by two blinded observers. In addition, circumferential profile analysis was conducted. RESULTS: By visual interpretation 25 segments displayed redistribution of the ribose, but not in the saline study, 14 reversible segments were seen on the saline study alone and 18 were seen on both studies (P = ns). In six patients ribose identified a greater number of redistributing segments and in a further six patients saline identified more reversible segments. Comparison of mean values of defect extent severity and percentage reversibility scores generated from the circumferential profile analysis showed no significant difference between the two arms of the study. CONCLUSION: A 5 min bolus injection of D-ribose following combined adenosine/dynamic exercise stress confers little benefit on the identification of redistribution of thallium-201. These results differ from those of previous studies which showed that a 30 min infusion of D-ribose following treadmill exercise significantly enhanced thallium redistribution. The duration of the ribose infusion is likely to be an important factor influencing the effect brought to bear on the redistribution of the tracer, and should be run over 30 min, or longer.

Adenosine↗
PubMed2000

Parathyroid glands: combination of (99m)Tc MIBI scintigraphy and US for demonstration of parathyroid glands and nodules.

PURPOSE: To determine the appropriate choice of imaging techniques for localization of nodular lesions of parathyroid glands. MATERIALS AND METHODS: First, computed tomographic (CT), magnetic resonance (MR), ultrasonographic (US), and technetium 99m methoxyisobutyl-isonitrile (MIBI) scintigraphic images in 49 patients with primary hyperparathyroidism were retrospectively evaluated. A single-blind, prospective study that included 16 patients with primary hyperparathyroidism was then conducted. MR, US, scintigraphic, and color Doppler US images of the neck were obtained and analyzed. RESULTS: In the retrospective study, CT, MR imaging, and US had low sensitivity (13%, 17%, and 27%, respectively) and specificity (39%, 65%, and 65%, respectively). Scintigraphy had 57% sensitivity and 85% specificity. In the prospective study, the use of latest-generation MR and US equipment and the participation of experienced operators led to improved sensitivity and specificity for these techniques. The combination of US and scintigraphy resulted in improved sensitivity (96%), specificity (83%), and positive and negative predictive values (88% and 94%, respectively), relative to the results obtained with either method alone. Doppler US was of little help in the setting of small glands. CONCLUSIONS: The combination of (99m)Tc MIBI scintigraphy and US performed by well-trained operators with up-to-date instruments appeared to be the best diagnostic tool for the preoperative diagnosis of parathyroid disease.

Adult↗
PubMed1992

Determination of extent and location of coronary artery disease in patients without prior myocardial infarction by thallium-201 tomography with pharmacologic stress.

Seventy-six patients undergoing pharmacologic stress 201TI tomography and coronary angiography within 14 +/- 12 days were studied to determine how well coronary artery disease extent and location could be determined by this scintigraphic technique. No patient had prior myocardial infarction or revascularization. Scintigrams were scored visually and quantitatively. Angiographic lesions > or = 50% were considered significant. Receiver operating characteristic curves were generated for the scintigrams against the angiographic gold standard. Predictive accuracies were determined and compared with the quantitative results. Predictive accuracy was 0.49 for visual and 0.58 for computer identification of single-vessel disease, 0.52 for both visual and computer identification of multivessel disease, 0.64 for both in correctly localizing left anterior descending artery disease, 0.78 versus 0.70 for the right coronary artery and 0.72 versus 0.68 for the left circumflex artery. For the overall detection of disease, the predictive accuracies were 0.79 and 0.80. Although high diagnostic accuracy for detection of coronary artery disease by this approach has been previously documented, the assessment of extent of disease in patients without prior myocardial infarction appears limited.

Adenosine↗
PubMed1989

[Inhalation scintigraphy of the lung using the new ultrafine aerosol Technegas].

Evaporation of 99mTc-pertechnetate at about 2500 degrees C on a carbon surface generates an ultrafine aerosol of labelled carbon clusters. Its particle size of about 2-5 nm enables the aerosol to behave similarly to a gas regarding the ability of penetration. After inhalation, the radioactive particles adhere to the walls of the respiratory bronchioli and alveoli. The high concentration of the radioactivity in the argon carrier gas makes it possible to record a scintigram after a single deep breath. We studied four healthy volunteers and 79 patients including 34 with a tentative diagnosis of pulmonary embolism, 20 with bronchus carcinoma, and 15 with various other lung diseases. Ten of these patients were infants, the youngest being nine months old. All patients also had a perfusion scintigraphy.

Administration, Inhalation↗
PubMed2002

The device and algorithm for estimation of the mechanoemisson chaos in blood of patients with gastric cancer.

The mechanoemission (ME) of blood is developed as a result of mechanochemical activation of a sample which is layered onto chromatographic paper. This paper describes computer-controlled device, aimed for generation, detection and analysis of ME data in the blood of the persons investigated. The original algorithm for estimation of ME chaos in blood is developed. For gastric cancer patients an increase of ME chaos is observed in comparison with healthy individuals and patients with inflammation of gastric mucosa. The concept of deterministic chaos is biohierarchical for the host of a cancer patient. In the light of this we have calculated that spatial chaos for gastric cancer patients is also increased in the geometrical structure of tumor cells and magnetic resonance imaging of the stomach. The concept of deterministic chaos may find an application in the development of new multi-computer organizations for medical diagnostic equipment.

Algorithms↗
PubMed1991

Bone growth and remodeling after distraction epiphysiolysis of the proximal tibia of the rabbit. Effect of electromagnetic stimulation.

The effect of pulsed electromagnetic stimulation on bone formation was tested in a lower-limb-lengthening model in the rabbit. Limb lengthening was performed by distraction epiphysiolysis. A specially designed external distraction device allowed 10 mm of lengthening of the tibia. Coils to generate a pulsed electromagnetic field were clipped onto the distractor. Stimulation started after a distraction period of three weeks and was continuous for 18 weeks. A control group received the same treatment without stimulation. Bone formation in the elongated zone was evaluated by computed tomography, scintigraphy, and histology. Bone healing involved accretion of callus followed by a process of remodeling, resulting in the formation of a solid cortex. The formation of a diaphysislike structure at the original site of the metaphysis progressed from the distal end of the elongated zone upward. Electromagnetic stimulation had no effect on the rate or extent of bone formation and remodeling.

Animals↗
PubMed1985

Integration of database capabilities into a patient reporting system.

A database design is described which automatically archives computer-generated patient imaging and radioassay reports. Selected phrases are condensed so that data storage will be efficient without sacrificing a prose style of report. An indexed file structure has been used to facilitate rapid record retrieval even when several hundred thousand records are stored. Personnel time is considerably reduced for recalling patient records, preparing periodic summaries of studies completed, and performing administrative functions such as billing and keeping track of checked out images. Complex queries, such as "list all the patients between the ages of 50 and 60 on digitalis referred for a stress cardiac study, with left ventricular ejection fraction less than 40% and apical dyskinesis," become feasible. A system for data backup is described to protect against catastrophic data loss.

Computers↗
PubMed2004

Gastric emptying and small intestinal transit time in preterm infants: a scintigraphic method.

OBJECTIVES: Practical methods to determine gastric emptying (GE) and small intestinal transit time in preterm infants are required. The aim of this study was to develop a scintigraphic method to determine GE and small intestinal transit time in preterm infants which produce minimal radiation exposure and physical disturbance in these infants. METHODS: Ten premature infants were studied. Median (and range) for gestational age was 28.9 (26-33) weeks, postnatal age was 19 (6-37) days, birth weight was 1194 (687-2300) grams and feeding volume was 173 (6-205) mL/kg/day. Nine of the patients were on nasal continuous positive airway pressure; one patient was on mechanical ventilation. A dose (0.2-0.4 MBq) of 99mTc-DTPA (0.5 mL) was given at the end of a meal administered by naso-gastric tube. Static images were obtained with a mobile gamma camera during the next 9 to 12 hours. The radiation dose was at most 0.30 mSv. Regions of interest (ROIs) were drawn around the stomach and the cecum. Time-activity curves were generated. Gastric emptying half-time (T(1/2)GE) was calculated. Residual gastric activity after 1 hour (R(1h)) and after 2 hours (R(2h)) was determined. Orocecal transit time was defined as the time until significant increase in activity was detected in the cecal ROI. RESULTS: Images showed gastric emptying in all cases. Median (range) half time was 1.0 (0.5-3.0) h. R(1h) was 37.5% (19% to 100%), R(2h) was 23% (6% to 61%). In one patient the tracer did not reach the cecum within 12 hours. In the remaining nine patients orocecal transit time was 3.1 (1.3-6.1) h. CONCLUSIONS: We present a new scintigraphic method to determine GE and orocecal transit time. It appears safe and practicable as a research tool in preterm infants.

Female↗
PubMedDate not supplied

Proposed: improve efficiency, reimbursement and LOS through better utilization of inpatient imaging procedures.

In recent years, most hospitals have gone through several rounds of cost cutting initiatives. While it is necessary and prudent to closely monitor operating costs and staff utilization, the focus needs to shift from cutting cost to increasing revenue. This study examines the potential financial benefit of performing diagnostic imaging procedures that are ordered on inpatients the day of, or the day prior to discharge as outpatient exams, following discharge. While this analysis focuses on revenue enhancement, it will not lose site of the fact that patient safety and quality clinical care always come first. We selected three imaging modalities for study: CT, MR and nuclear cardiology. These modalities are unique because of their expensive nature, length of time to complete, and limited availability. Also, they typically yield the highest reimbursement per procedure when compared to other diagnostic imaging procedures. Yearly volume at North Shore University Hospital for CT, MR and nuclear cardiology studies performed on the day of or day before discharge is projected to be 1,120 studies. Sixty-two percent of the total is generated by nuclear stress tests, 34 percent by CT, and only 6 percent is related to MR. On an annual basis, approximately $840,800 in hospital charges will be generated for inpatient procedures performed on the day of or one day before discharge. Implementing change is a difficult and complicated process. The following are among many factors that must be carefully considered: physician education, consensus building, patient care guidelines, ongoing performance improvement activities and scheduling. This study focused on a small aspect of inpatient procedure utilization and identified reimbursement to the hospital. The most significant finding of this project relates to the fact that of the 323 CT and MR studies performed, 83 percent of the findings were positive, and the patients were still discharged. That fact further supports the concept of performing studies ordered on the day of or one day prior to discharge as outpatient procedures.

Ambulatory Care↗
PubMed2003

[Guideline for in vivo- and in vitro procedures for thyroid diseases (version 2)].

The version 2 of the guideline for diagnostic standards of thyroid disorders is an update of the guideline published in 1999 and describes standards of in vitro and in vivo procedures. The following statements are modified: In vitro procedures: When measurement of the TSH-receptor antibodies is indicated, the guideline recommends the use of a second generation assay (recombinant human TSH-receptor as antigen). The functional assay sensitivity for the measurement of thyroglobulin should reach a value < or =1 ng/ml. Molecular genetic tests (RET proto-oncogene) are indicated in patients with a newly diagnosed medullary thyroid cancer and in the relatives of patients with hereditary medullary thyroid cancer. In vivo procedures: The sonographic examination should use a probe with a frequency of at least 7.5 MHz. Indications for the thyroid scintigraphy: nodule size > or =1 cm in diameter, autonomous goitre/nodule with clinical or subclinical hyperthyroidism, necessity of a differentiation between Graves' disease and chronic lymphocytic thyroiditis, therapy control after a definitive treatment and - in individual cases - the follow-up of untreated autonomous nodules.

Autoantibodies↗