Search PubMed⌕ Search

Biomedical subjects

A Alavi

Publications and source records attributed to A Alavi.

At least 415 records · Page 23Linked to original sources
PubMed1976

Bone marrow scan evaluation of arthropathy in sickle cell disorders.

Twelve patients with sickle cell hemoglobinopathies and arthropathy were studied, using technetium Tc 99m sulfur colloid bone marrow scans. Eight of 12 had decreased marrow radionuclide activity adjacent to painful joints, suggestion obliteration of vessels supplying bone marrow. Four patients without marrow defects on scanning had causes other than infarction for their joint symptoms, viz, small fractures, postinfectious synovitis, degenerative arthritis, and osteochondromas. Roentgenograms never showed bony abnormalities in five patients with marrow infarctions, and, in three others, showed defects several months later than did the marrow scans. Bone marrow scans offer a sensitive and early diagnostic aid in sickle cell hemoglobinopathies with arthropathy.

Adult↗
PubMed1976

[Synovectomies of the knee. Apropos of 47 cases tuberculous synovitis].

UNLABELLED: The authors carried out synovectomy of the knee in 70 cases, including 47 for tuberculous synovitis, with follow up periods of 2 years and half to 18 years. The subjects included: -30 children from 2 to 15 years; -17 adults from 16 to 50 years, with 3 cases of more than 50 years. RESULTS: Very good: greater or equal to 110 degrees in 2 cases; -Good: greater or equal to 90 degrees in 26 cases; -Average: greater or equal to 45 to 90 degrees in 11 cases; -Poor: less than 45 degrees in 8 cases. The authors believe that synovectomy in tuberculous synovitis of the knee without an osteocartilagenous lesion, or with slight lesions of the joint is more efficacious than medical treatment alone and may shorten the duration of treatment.

Adolescent↗
PubMed1975

Local cerebral blood volume determined by three-dimensional reconstruction of radionuclide scan data.

We developed a method to determine in man absolute values of local cerebral blood volume (LCBV) localized throughout the brain in three dimensions and presented in a cross-sectional picture format. Previously, absolute values of LCBV have been determined in vivo by stimulated X-ray fluorescence, but these determinations have been limited to one point in the brain at a time. All other previous estimates of LCBV by external emission counting have been contaminated by the significant contribution of blood in the overlying scalp and cranium. In our method, a transverse section scan is made after the injection of -99m-Tc-labeled red blood cells into a peripheral vein. Data processing then gives a point-to-point estimate of absolute radionuclide concentration analogous to an autoradiograph. After the concentration of blood activity is determined, counting data are converted to a two-dimensional map of LCBV representing a cross section at a known level of the brain. In a series of five baboons, the following equation was obtained for the regression plane that relates LCBV in the center of the brain to arterial carbon dioxide tension (P-ALPHA-CO2) and mean arterial blood pressure (MABP): LCBV equals 2.88 + 0.049P-ALPHA-CO2 MINUS 0.013MABP. In patients, LCBE values ranged from 2 to 4 ml/100 g depending on location; higher values corresponded to regions of cerebral cortex. Differences in blood volumes of focal brain lesions were also quantified.

Animals↗
PubMedDate not supplied

A detailed evaluation of patients with acute pulmonary embolism and low- or very-low-probability lung scan interpretations.

BACKGROUND: To determine the clinical characteristics of patients with pulmonary embolism (PE) and low- or very-low-probability ventilation-perfusion lung scan interpretations. METHODS: A retrospective analysis of the data obtained during the Prospective Investigation of Pulmonary Embolism Diagnosis study was performed. The clinical characteristics of patients with acute PE and low- or very-low-probability lung scan interpretation (false-negative interpretations) were compared with patients who had low- or very-low-probability lung scan interpretations and no evidence of acute PE (true-negative interpretations). RESULTS: Of the 1493 patients who gave consent to participate in the Prospective Investigation of Pulmonary Embolism Diagnosis study, 399 patients had angiographic or autopsy evidence of acute PE. Pulmonary embolism was excluded in 960 patients. Patients with false-negative lung scan interpretations more commonly had a history of immobilization (P < .0001), trauma to the lower extremities (P < .003), recent surgery (P < .002), or central venous instrumentation (P < .04) compared with patients with true-negative lung scan interpretations. In patients with low- or very-low-probability lung scan interpretations and none of the above-mentioned risk factors, the prevalence of PE was only 4.5%. In contrast, for patients with low- or very-low-probability lung scan interpretations and two or more of the above-mentioned risk factors, the prevalence of PE was 21%. CONCLUSIONS: Patients with a history of immobilization, trauma to the lower extremities, recent surgery, or central venous instrumentation were more likely to have false-negative lung scan interpretations. Therefore, this population warrants special attention when deciding on the need for peripheral venous studies or angiography in patients with low- or very-low-probability lung scan interpretation.

Acute Disease↗
PubMedDate not supplied

Induced renal artery stenosis in rabbits: magnetic resonance imaging, angiography, and radionuclide determination of blood volume and blood flow.

To investigate the ability of MRI to detect alterations due to renal ischemia, a rabbit renal artery stenosis (RAS) model was developed. Seven rabbits had RAS induced by surgically encircling the artery with a polyethylene band which had a lumen of 1 mm, 1 to 2 weeks prior to imaging. The stenosis was confirmed by angiography, and the rabbits were then imaged in a 1.4 T research MRI unit. T1 was calculated using four inversion recovery sequences with different inversion times. Renal blood flow, using 113Sn-microspheres, and regional water content by drying were then measured. The average T1 of the inner medulla was shorter for the ischemia (1574 msec) than for the contralateral kidney (1849 msec), while no change ws noted in the cortex. Ischemic kidneys had less distinct outer medullary zones on IR images with TI = 600 msec than did contralateral or control kidneys. Blood flow to both the cortex and medulla were markedly reduced in ischemic kidneys compared with contralateral kidneys (119.5 vs. 391 ml/min/100 gm for cortex and 19.8 vs. 50.8 ml/min/100 gm for medulla). Renal water and blood content were less affected. Our rabbit model of renal artery stenosis with MRI, radionuclide, and angiographic correlation has the potential to increase our understanding of MR imaging of the rabbit kidney.

Angiography↗
PubMedDate not supplied

Early changes in thallium distribution. Effect on quantitative analysis.

Thirty-two patients with coronary artery disease and an abnormality on an initial anterior view thallium scan had repeat images obtained after delays of 30 and 240 minutes. Scans were analyzed by quantitative criteria. Comparison of the initial stress study with the 30-minute redistribution scan showed no significant change in 11 patients, defects becoming smaller in 13 patients, and defects becoming larger in eight patients. When comparing the stress or the early redistribution images with the late redistribution scans, the diagnosis (eg, scar vs. ischemia) would have been affected in 14 cases. Analysis of the sources of variability showed that all the apparent worsening but only part of the defect resolution could be explained by variability inherent to repositioning the patient. Thus, the size of an initial defect is very sensitive to the time between the end of exercise and the onset of data collection and the nature of changes in scan appearance is complex.

Adult↗
PubMedDate not supplied

Subcortical metabolic alterations in partial epilepsy.

The function of subcortical nuclei in partial epilepsy was investigated using positron emission tomography (PET) to measure metabolism in the basal ganglia and thalamus. Sixteen patients undergoing surgical evaluation were studied with 18F-fluorodeoxyglucose (FDG) interictally and had intensive extracranial and intracranial electrophysiologic evaluations. Eight patients had left temporal lobe seizure foci, six had right temporal lobe foci, and two had right posterotemporal or parietal foci. The PET data were analyzed visually and quantitatively, using a multivariate analysis of variance on the quantitative data. Hypometabolism of subcortical nuclei was present ipsilateral to the cortical seizure focus. Cortical hypometabolism was noted focally in the temporal lobe in patients with left temporal lobe seizure foci, whereas patients with right temporal lobe seizure foci had diffuse hemispheric hypometabolism. We postulate that the subcortical hypometabolism is secondary to decreased efferent activity from temporal lobe structures, in particular amygdala and hippocampus, to subcortical nuclei. Diminished subcortical activity may then lead to defective regulation of cortical excitability in the temporal lobe, increasing the likelihood of seizure development and spread.

Adult↗
PubMedDate not supplied

Realities of diagnosing Helicobacter pylori infection in clinical practice: a case for non-invasive indirect methodologies.

BACKGROUND: The current, arbitrarily defined gold standard for the diagnosis of H. pylori infection requires histologic examination of two specially stained antral biopsy specimens. However, routine histology is potentially limited in general clinical practice by both sampling and observer error. The current study was designed to examine the diagnostic performance of invasive and non-invasive H. pylori detection methods that would likely be available in general clinical practice. METHODS: The diagnostic performance of rotating clinical pathology faculty using thiazine staining was compared with that of an expert gastrointestinal pathologist in 38 patients. In situ hybridization stains of adjacent biopsy cuts were also examined by the expert pathologist for further comparison. Receiver operator characteristic (ROC) analysis was performed to evaluate whether the diagnostic performance of the expert pathologist differed depending upon the histologic method employed. A similar analysis was made to evaluate the diagnostic performance of pathology trainees relative to the expert. In the absence of an established invasive gold standard, non-invasive testing methods (rapid serum antibodies, formal Elisa antibodies and carbon-14 urea breath testing) were evaluated in 74 patients by comparison with a gold standard defined using a combination of diagnostic tests. RESULTS: Using either rapid urease testing of biopsy specimens or urea breath testing as the gold standard for comparison, the diagnostic performance of the rotating clinical pathology faculty was inferior to that of the expert gastrointestinal pathologist especially with regard to specificity (e.g., 69 percent for the former versus 88 percent, with the latter relative to rapid urease testing). Although interpretation of in situ hybridization staining by the expert appeared to have an even higher specificity, ROC analysis failed to show a difference. The mean ROC areas for thiazine and in situ hybridization staining for trainee pathologists relative to the expert were 0.88 and 0.94, respectively. In untreated patients, urea breath testing had a sensitivity and specificity of 100 percent as compared with thiazine staining with a sensitivity of 83 percent and a specificity of 97 percent. Post-therapy, breath testing had a sensitivity of 100 percent but a specificity of only 86 percent as compared with invasive testing with a sensitivity and specificity of 100 percent. Rapid serum antibody testing and formal Elisa antibody testing agreed in 93 percent of cases (Kappa 0.78) with the rapid test being correct in three of the four disagreements. CONCLUSIONS: The current study illustrates a number of realities regarding H. pylori diagnosis. There is no diagnostic gold standard in general clinical practice. Accurate interpretation of specially stained slides is a learned activity with a tendency towards overdiagnosis early on. Urea breath testing is likely to be the diagnostic method of choice for untreated patients in general clinical practice although antibody testing is almost as accurate. Rapid antibody tests are at least as accurate as formal Elisa antibody tests. Urea breath testing is useful for confirming cure after therapy, but false-positive results may occur in some patients.

Biopsy↗
PubMedDate not supplied

Positron emission tomography imaging in evaluation of cancer patients.

Positron emission tomography (PET) is a diagnostic imaging technique that has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality. The most widely used radiotracer in PET is Fluorine18-fluorodeoxyglucose (F18-FDG), which is an analogue of glucose. The FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors PET has a high sensitivity and a high negative predictive value. PET with FDG is now the standard of care in initial staging, monitoring the response to the therapy, and management of lung cancer, colonic cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. Other indications of PET like bone tumor, ovarian cancer and cancer of unknown primary (CUP) has also been discussed in brief. The aim of this review article is to review the clinical applications of PET in various malignancies and only limited number of important studies will be discussed for this effort.

Fluorodeoxyglucose F18↗