Tc-99m MDP uptake in a cerebral infarct.
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Aged↗
Biomedical subjects
R J Hicks
Publications and source records attributed to R J Hicks.
Asymptomatic prostate nodules.
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Decision Support Techniques↗
Assessment of right ventricular oxidative metabolism by positron emission tomography with C-11 acetate in aortic valve disease.
Evaluation of right ventricular (RV) oxidative metabolism is limited by the inability to easily determine oxygen extraction by the RV myocardium and the complex morphology of this ventricle. Because left ventricular C-11 clearance rate constants closely correlate with myocardial oxygen consumption, it was postulated that C-11 clearance rate constants for the RV free wall should also reflect its oxygen consumption. Therefore, RV C-11 clearance rate constants were compared with RV loading in 21 patients with aortic valve disease to assess the possible use of this technique for noninvasive evaluation of RV oxidative metabolism. RV free wall C-11 clearance rate constants correlated with the product of systolic pulmonary artery pressure and heart rate for all patients (r = 0.65, p = 0.002), but the relation was stronger if 2 patients with overt RV dysfunction were excluded (r = 0.83, p = 0.001). On the basis of mean pulmonary artery pressures, patients were stratified into subgroups with normal (group I, n = 8) and elevated (group II, n = 13) pulmonary pressures and were compared with 10 normal control subjects. RV C-11 clearance rate constants were significantly higher in group II than in group I and in normal control subjects (p less than 0.05). These data suggest that RV C-11 acetate clearance rate constants can provide noninvasive evaluation of RV oxidative metabolism. This technique may allow serial assessment of RV performance in various cardiac and pulmonary diseases, and particularly of changes associated with therapeutic interventions.
Acetates↗
Quantitative evaluation of regional substrate metabolism in the human heart by positron emission tomography.
Meaning interpretation of metabolic images obtained by positron emission tomography for evaluation of cardiac disease requires a knowledge of the normal variation in regional myocardial substrate metabolism. Recent studies with fluorine-18 (F-18) fluorodeoxyglucose suggest inhomogeneity of myocardial glucose metabolism in the normal human heart, which may relate to substrate availability. Therefore, quantitative evaluation of myocardial oxidative metabolism and glucose metabolism, as derived by dynamic positron emission tomography with carbon-11 (C-11) acetate and F-18 fluorodeoxyglucose, was performed in nine healthy male volunteers. All were studied under tightly controlled metabolic conditions of hyperinsulinemic-euglycemic clamping with and without a concurrent lipid emulsion infusion. Significant inhomogeneity of regional glucose metabolism was noted although it was less than that described under fasting conditions. Glucose utilization was 13% lower in the septum compared with the lateral wall both without and with lipid infusion (0.34 vs. 0.39 mumol/g per min, respectively, p less than 0.05; and 0.33 vs. 0.38 mumol/g per min, respectively, (p less than 0.05). Relatively decreased septal glucose utilization could not be explained by decreased metabolic demand because C-11 clearance constants were marginally higher in the septum than in the lateral wall in both studies (0.055 vs. 0.054 per min, respectively, p = NS; and 0.061 vs. 0.056 per min, respectively, p less than 0.05). Relatively decreased septal glucose utilization could reflect regional variation in substrate use and possible preferential free fatty acid utilization by the septum. These data provide a useful framework for assessing altered cardiac metabolism in disease and support standardization of metabolic conditions during metabolic imaging with positron emission tomography.
Acetates↗
Identification of an infected seroma by triple-phase bone scintigraphy and instillation of Tc-99m sulfur colloid.
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Body Fluids↗
Normalization of left ventricular ejection fraction following resection of pheochromocytoma in a patient with dilated cardiomyopathy.
Catecholamine-induced cardiomyopathy associated with pheochromocytoma is a well-recognized but rare entity. Both hypertrophic and dilated variants have been described. We report a case of dilated cardiomyopathy associated with a benign pheochromocytoma that showed complete normalization of left ventricular systolic function following removal of the tumor. Serum noradrenaline and dopamine were significantly elevated without elevation in serum adrenaline levels. This may be the first report in which radionuclide ventriculography was used to document the time course of normalization in LVEF following removal of a pheochromocytoma.
Adolescent↗
Absent splenic uptake of indium-111-oxine-labeled autologous leukocytes in functional asplenia.
An incidental finding of absent splenic uptake of autologous, indium-111-oxine-labeled leukocytes in an immunosuppressed renal transplant recipient was documented to be associated with functional asplenia based on absence of technetium-99m-sulfur colloid clearance by a morphologically normal spleen. The patient had recently suffered an episode of disseminated varicella infection that might have led to the development of functional asplenia.
Adult↗
111In-oxine labelled leukocyte scintigraphy in the detection and localization of active inflammation and sepsis.
We report an analysis of the results obtained in our first 100 studies with indium-111-oxine labelled leukocyte scintigraphy, a diagnostic technique which has recently become available for clinical evaluation within Australia. We used this technique to assess patients with suspected sepsis or inflammation after other commonly used investigations had failed to confirm a diagnosis. Four patient subgroups were evaluated: fever of unknown origin; suspected abdominal or postoperative sepsis; suspected active inflammatory bowel disease; and suspected sepsis or inflammation of bones or joints. The course of all patients was followed for at least three months to establish the accuracy of the technique. The leukocyte labelling procedure took 90 min and imaging was carried out typically 3-6, 24 and occasionally 48 h after reinjection of the labelled autologous leukocytes. In one patient labelling of leukocytes was unsuccessful. In the remaining 99 studies the overall sensitivity of leukocyte scintigraphy was 88% (36 of 41 patients with a proved inflammatory or infective disease focus had positive scan findings); and the specificity was 95% (55 of 58 cases with no proved disease focus had normal scan findings). This series supports the use of this method as the imaging procedure of choice in nuclear medicine for the evaluation of suspected acute sepsis (symptoms less than four weeks' duration), of inflammatory bowel disease and of suspected infections involving appendicular bones which contain no active bone marrow. It is also a useful secondary scintigraphic procedure, after gallium-67-citrate scintigraphy, in patients with suspected infective disorders of more than four weeks' duration.
Abdomen↗
Association between false negative hepatobiliary scans and initial gallbladder visualization after 30 min.
We have reviewed the experience of our institution and the literature concerning the use of hepatobiliary scintigraphy for the diagnosis of acute cholecystitis. The aim of this study was to assess whether the hepatobiliary scintigraphic finding of initial gallbladder visualization within 30 min is a more reliable criterion for excluding acute cholecystitis than gallbladder visualization within 1 h after tracer injection. In our institution's consecutive series, 113 of 211 hepatobiliary studies had gallbladder visualization within 1 h. Gallbladder visualization time in this group had a log normal distribution, with gallbladder visualization occurring within 30 min in 107 of 113 (95%). Gallbladder visualization occurred between 31 and 60 min in only 6 (5%); nevertheless, our one false negative study came from this small subgroup of patient studies (P = 0.05). Review of the literature (1645 patients with iminodiacetic acid [99mTc-IDA] derivative studies) revealed 6 further timed false negative results with gallbladder visualization within 1 h. Of these studies, in 4 (67%) the gallbladder was visualized between 31 and 60 min and in only 2 before 30 min. One of these latter 2 patients had a rare anatomy. Analysis of the pooled institutional and literature data gave an estimated false negative rate of 21% if the gallbladder was visualized between 31 and 60 min. This was significantly higher (P less than 0.001) than the 0.5% false negative rate when the gallbladder was seen prior to 30 min, but similar to the false negative rate of 16% reported by Weissmann et al. for studies with initial visualization after 1 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
Review and evaluation of the effects of xenobiotic chemicals on microorganisms in soil.
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Bacteria↗
Three-dimensional assessment of myocardial oxidative metabolism: a new approach for regional determination of PET-derived carbon-11-acetate kinetics.
We have developed a new analysis algorithm which generates polar coordinate maps of myocardial carbon-11-(11C) acetate kinetics. In 10 normal subjects (n = 20 studies), myocardial 11C clearance rate constants (k) averaged 0.057 +/- 0.009 (per minute). Regional k-values varied only 10.6 +/- 2.4% in the normal left ventricle. However, there was a small but significant segmental variation with increased 11C clearance in the septal, anterior, and basal regions (p less than 0.05). Since 11C clearance rates reflect tri-carboxylic acid cycle flux, these results suggest that myocardial oxidative metabolism is relatively homogeneous in the normal human heart at rest with minor regional variations, which possibly reflect varying regional wall stresses or substrate utilization. The proposed approach provides three-dimensional evaluation of regional oxidative metabolism which will permit characterization of the location, extent, and severity of myocardial disease.
Acetates↗
The radionuclide assessment of a system for slow intrathecal infusion of drugs.
The authors describe a new radionuclide method for assessing the functional integrity of slow intrathecal infusion devices. Approximately 11 mCi (400 MBq) of Tc-99m DTPA is injected into the pump chamber. Early and delayed imaging of the pump, tubing, and spinal cerebrospinal fluid space is performed on a digital large-field-of-view gamma camera. The digitally displayed images are then reviewed by adjustment of the grey scale window. Four patients have had eight studies and in each case the result has been confirmed by surgical exploration or by clinical response to change in therapy.
Aged↗
Isolation and characterization of quinoline-degrading bacteria from subsurface sediments.
Two gram-negative, motile bacteria isolated from deep subsurface sediments mineralized the nitrogen-containing polyaromatic hydrocarbon quinoline under aerobic conditions and transformed quinoline to soluble intermediates under anaerobic conditions. Many aromatic compounds were also able to serve as the sole source of carbon and energy under aerobic conditions. Rapid aerobic mineralization of quinoline at concentrations as low as 0.002 microgram ml-1 indicates that these organisms possess a high-affinity uptake and utilization system, which may reflect the oligotrophic nature of deep subsurface environments. Both bacteria harbored four plasmids of identical size, ranging from 50 to 440 kilobases.
Aerobiosis↗
Plasmid incidence in bacteria from deep subsurface sediments.
Bacteria were isolated from deep terrestrial subsurface sediments underlying the coastal plain of South Carolina. A total of 163 isolates from deep sediments, surface soil, and return drill muds were examined for plasmid DNA content and resistance to the antibiotics penicillin, ampicillin, carbenicillin, streptomycin, kanamycin, and tetracycline. MICs of Cu, Cr, and Hg for each isolate were also determined. The overall frequency of plasmid occurrence in the subsurface bacteria was 33%. Resistance was most frequent to penicillin (70% of all isolates), ampicillin (49%), and carbenicillin (32%) and was concluded to be related to the concentrations of the individual antibiotics in the disks used for assaying resistance and to the production of low levels of beta-lactamase. The frequencies of resistance to penicillin and ampicillin were significantly greater for isolates bearing plasmids than for plasmidless isolates; however, resistance was not transferable to penicillin-sensitive Escherichia coli. Hybridization of subsurface bacterial plasmids and chromosomal DNA with a whole-TOL-plasmid (pWWO) probe revealed some homology of subsurface bacterial plasmid and chromosomal DNAs, indicating a potential for those bacteria to harbor catabolic genes on plasmids or chromosomes. The incidences of antibiotic resistance and MICs of metals for subsurface bacteria were significantly different from those for drill mud bacteria, ruling out the possibility that bacteria from sediments were derived from drill muds.
Journal Article↗
The effects of afterload reduction on myocardial carbon 11-labeled acetate kinetics and noninvasively estimated mechanical efficiency in patients with dilated cardiomyopathy.
METHODS AND RESULTS: With echocardiography and dynamic carbon 11-labeled acetate (C-11 acetate) positron emission tomographic imaging, C-11 acetate kinetics and a parameter that estimates mechanical ventricular efficiency (the work metabolic index) were defined in eight patients with dilated cardiomyopathy. The effect of afterload reduction with nitroprusside on these parameters was evaluated in six of these patients. Nitroprusside increased stroke work index but decreased the C-11 clearance rate. The work metabolic index determined noninvasively increased and correlated well with an invasive approach. The work metabolic index was inversely correlated with systemic vascular resistance. Nitroprusside shifted this relationship upward and to the left. CONCLUSION: This method of estimating efficiency is feasible and may represent a unique noninvasive approach for the evaluation of cardiac performance and responses to therapy.
Adult↗
Metabolic imaging by positron emission tomography early after myocardial infarction as a predictor of recovery of myocardial function after reperfusion.
BACKGROUND: Myocardial ischemia leads to alterations in myocardial substrate metabolism that have been shown to reflect severity of ischemic injury. The purpose of this study was to correlate oxidative metabolism with recovery of contractile function in patients with acute myocardial infarction. METHODS AND RESULTS: Regional blood flow and oxidative metabolism were assessed by dynamic positron emission tomography early after myocardial infarction treated with thrombolytic therapy in 18 patients. The extent of myocardial perfusion abnormally (carbon 11-labeled acetate uptake; relative amplitude < or = 50%) was inversely correlated with the ejection fraction obtained within 8 hours of the onset of chest pain (r = -0.81; p - 0.01) but not clearly with that at follow-up 1 week later (r = 0.64; p = 0.09). Oxidative metabolism (carbon 11-labeled acetate; monoexponential clearance) was higher in periinfarct territories with early or late recovery of contractile function than in those without, but there was a large overlap in absolute values limiting the predictive power of a single measurement. Relatively preserved oxidative metabolism compared with perfusion in low-flow areas was predictive of early (day 1 to 1 week) and delayed (week 1 to beyond 1 month) recovery. Normal resting perfusion with regionally decreased oxidative metabolism predicted early recovery of contractile function. CONCLUSION: Thus in patients studied with positron emission tomography early after myocardial infarction, comparison of regional perfusion and oxidative metabolism was more predictive of recovery in contractile function than was assessment of either one alone.
Adult↗
"Magnetic resonance imaging negative positron emission tomography positive" temporal lobe epilepsy: FDG-PET pattern differs from mesial temporal lobe epilepsy.
PURPOSE: Some patients with temporal lobe epilepsy (TLE) lack evidence of hippocampal sclerosis (HS) on MRI (HS-ve). We hypothesized that this group would have a different pattern of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) hypometabolism than typical mesial TLE/HS patients with evidence of hippocampal atrophy on magnetic resonance imaging (MRI) (HS+ve), with a lateral temporal neocortical rather than mesial focus. PROCEDURES: Thirty consecutive HS-ve patients and 30 age- and sex-matched HS+ve patients with well-lateralized EEG were identified. FDG-PET was performed on 28 HS-ve patients and 24 HS+ve patients. Both groups were compared using statistical parametric mapping (SPM), directly and with FDG-PET from 20 healthy controls. RESULTS: Both groups showed lateralized temporal hypometabolism compared to controls. In HS+ve, this was antero-infero-mesial (T = 17.13); in HS-ve the main clustering was inferolateral (T = 17.63). When directly compared, HS+ve had greater hypometabolism inmesial temporal/hippocampal regions (T = 4.86); HS-ve had greater inferolateral temporal hypometabolism (T = 4.18). CONCLUSIONS: These data support the hypothesis that focal hypometabolism involves primarily lateal neocortical rather than mesial temporal structures in 'MRI-negative PET-positive TLE.'
Adult↗
A comparison of MRI and PET scanning in surgically staged loco-regionally advanced cervical cancer: potential impact on treatment.
The aim of this study was to assess whether positron emission tomography (PET) or magnetic resonance imaging (MRI) could obviate the need for surgical staging in patients with locally advanced cervical carcinoma being planned for radiotherapy (RT). Imaging findings were compared to surgical staging in 27 patients including three with recent resection of the primary tumor. Both PET and MRI visualized all 24 residual cervical tumors. Primary tumor volume, as measured by MRI scan, ranged from 1.25 cc to 140 cc. In 24 patients evaluable for pelvic nodal status, PET had sensitivity, specificity, and positive and negative predictive values of 83%, 92%, 91% and 85%, respectively, with 88% accuracy. MRI detected only six in 12 (50%) patients with confirmed pelvic nodal disease, all of which were also seen by CT and PET, with an overall accuracy of 75%. PET detected only four in seven (57%) cases with confirmed para-aortic (PA) involvement. All histologically confirmed sites not visualized on PET were <1 cm. Without surgical staging, six in 10 (60%) patients with histologically proven pelvic nodal disease would not have received pelvic boost if guided by MRI alone, compared to two in 10 (20%) patients guided by PET alone or in combination with MRI. All four patients with positive PA on PET were confirmed on histology or clinical follow-up, including one case that proved to be a false negative one on surgery. However, in three cases, PET would have yielded an inadequate radiation volume. In conclusion, the positive predictive value of PET in the pelvis and para-aortic region appears sufficient to obviate lymph nodal sampling, but sampling is still required to exclude small-volume disease cranial to sites of abnormality on PET. MRI has insufficient accuracy for nodal staging to impact management.
Adenocarcinoma↗