Search PubMed⌕ Search

Biomedical subjects

A Alavi

Publications and source records attributed to A Alavi.

At least 271 records · Page 15Linked to original sources
PubMed1989

Alzheimer's disease with prominent visual symptoms. Clinical and metabolic evaluation.

The authors examined eight patients with dementia of the Alzheimer's type (DAT), five with prominent visual symptoms early in the illness (VS) and three with no visual symptoms (NVS). Results of neuro-ophthalmologic examinations on VS patients showed relatively consistent abnormalities in figure copying, color vision tested by isochromatic plates, and stereopsis. Cerebral glucose metabolism determined by 18F-fluoro-2-deoxyglucose positron emission tomography (PET) was unchanged in primary visual cortex of VS and NVS patients compared with 12 normal volunteers of similar age and sex. Glucose metabolism in VS patients was decreased by 45 and 34% in left and right visual association cortex (P less than 0.01 and P less than 0.05, respectively) and 34 and 37% in left and right inferior parietal cortex (P less than 0.05) compared with controls; NVS patients had no significant metabolic alteration in these areas. Symptoms, physical examination, and metabolic imaging imply that these patients are a heterogenous but distinct clinical subgroup of DAT often with mild dementia who have visual symptoms due primarily to visual agnosia.

Aged↗
PubMed1989

Differentiation of bone and bone marrow infarcts from osteomyelitis in sickle cell disorders.

To determine whether imaging techniques can differentiate osteomyelitis from bone infarction in sickle cell disorders, 39 sets of bone scans (BS) and bone marrow scans (BMS) were performed on 31 patients with sickling disorders and bone pain. In addition, three patients who had either a BS or a BMS were included. Results were analyzed according to whether scans were performed three days or less (Period 1), four to six days (Period 2), or seven or more days (Period 3) after the onset of pain. Regardless of the period, all but five BMS for 34 episodes of assumed infarction showed decreased uptake. BS findings varied depending on the time interval, with none of the ten in Period 1 showing increased uptake, but all 11 in Period 3 showing increased uptake. However, in Period 2, about half of the 13 BS showed increased uptake. All three patients with osteomyelitis in Period 3 had increased uptake on BS. The BMS done in one of these patients showed decreased uptake. Three patients with cellulitis had normal BS and BMS. One patient with septic arthritis had normal BMS, but slightly increased uptake on BS. Although typical imaging patterns are present in early and late infarction (Periods 1 and 3), the patterns for late infarction may not differ from those of advanced osteomyelitis. Therefore, imaging studies are only of value in differentiating infarction from osteomyelitis when both BS and BMS are performed soon after the appearance of symptoms.

Adolescent↗
PubMed1989

The clinical utility of the Tc-99m SC intraperitoneal scan in CAPD patients.

The intraperitoneal instillation of dialysate increases intra-abdominal pressure and consequently predisposes to subcutaneous infiltration, leaks, and herniations through defects in the abdominal wall. In this setting, the incidence of abdominal hernias ranges between 9% and 24%. Life-threatening complications (incarceration/strangulation) occur in up to 13.2% of hernias. Therefore, the authors evaluated the efficacy of the Tc-99m sulfur colloid (SC) intraperitoneal scan in the detection of abdominal leaks and hernias in 11 continuous ambulatory peritoneal dialysis (CAPD) patients over a 2-year period at the Hospital of the University of Pennsylvania. Eleven patients (7M, 4F) ranging in age from 24 to 72 (mean = 50.8), on CAPD, were evaluated for clinically suspected abdominal hernias or dialysate leaks with intraperitoneally administered Tc-99m SC. After the injection of 3-5 mCi of Tc-99m into a standard 2 liter dialysate bag, multiple sequential anterior images of the abdomen were obtained in the supine position over the course of one hour. Delayed images were obtained after ambulation and post-drainage two or more hours postinjection in multiple projections and positions in order to demonstrate any abnormal focal accumulations of fluid to the best advantage. Any detected abnormalities were marked and correlated with the physical examination and the patient's symptoms. Two patients had normal scans. Of the nine abnormal scans, five hernias were identified in four patients and six leaks were detected in the other five patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The aging brain.

Explore the source record for details and available documents.

Adolescent↗
PubMed1989

PET, CT, and MRI in the evaluation of neuropsychiatric disorders: current applications.

Positron emission tomography (PET) is emerging as a very useful clinical tool and is adding a great deal to our understanding of the pathophysiology of central nervous system (CNS) disorders. Although computed tomography (CT) and magnetic resonance imaging (MRI) have had a dramatic impact on patient management, there is often an important associated function abnormality which is best assessed by PET. In normal aging and in dementia, the CT and MRI brain changes of atrophy and white matter abnormalities are frequently nonspecific. PET has been more diagnostic, showing characteristic regional metabolic abnormalities. Evaluation of brain tumors such as astrocytomas with PET has demonstrated better correlation with histologic grade compared to CT. Unlike CT or MRI, PET can help to distinguish radiation necrosis from recurrent tumor, and can differentiate the extent of metabolically active tumor from surrounding edema. PET is useful in evaluating stroke patients, providing better prognostic information and demonstrating abnormalities sooner than CT. In epilepsy, PET appears to be superior to MRI in localizing seizure foci in patients with partial seizures. In head trauma patients, metabolic patterns are being described which will likely have an effect on patient management. The use of PET in schizophrenia has yielded very interesting results, with common patterns of metabolic abnormalities being demonstrated. CT and MRI in these patients have not been very useful. PET has also shown promise in movement disorders such as Huntington's disease. It is now clear that PET is already clinically useful and can provide valuable information unobtainable by CT and MRI. As new radioligands are developed, PET is certain to assume an even more important role in the future.

Central Nervous System Diseases↗
PubMed1989

Effect of the Garren-Edwards gastric bubble on gastric emptying.

The Garren-Edwards Gastric Bubble (GEGB) was introduced in 1984 as an alternative to surgery (jaw wiring, gastrointestinal bypass, vertical banded gastroplasty) for the treatment of morbid obesity in patients who had failed behavior modification therapy or dietary management for weight reduction. Its mechanism of action is unclear and previous reports have not demonstrated any significant consistent alteration in gastric emptying (GE) as measured by radionuclide techniques. Other proposed mechanisms include: placebo, hormonal, mechanical "satiety", behavioral modification, and neuronal. In order to determine the effect of the GEGB on GE, ten obese (mean % overweight = 89%) patients, 27-50 yr old (mean = 36 yr), had solid GE scans before and 5 wk after endoscopic placement of the bubble. GE scans were performed in six patients after removal (12 = wk residence time). The meal consisted of 300 microCi [99mTc]sulfur colloid in the form of a 300 kcal egg sandwich (egg white 248 g, white bread 40 g, butter 6 g; composition = CHO 40:PR 40: FAT 20) with 180 ml deionized water. Images were obtained in the anterior and posterior projections at 15-min intervals for 1 hr (four patients) or 2 hr (six patients) and the %GE (decay corrected geometric mean) was calculated. Unlike other studies involving the GEGB, adjunctive therapy in the form of dieting and behavior modification were not employed in this study. The effect of the GEGB alone in the treatment of obesity has not been previously evaluated. There was a significant (p less than 0.025) delay in gastric emptying at 1 hr (pre-bubble mean % gastric retention = 46%; bubble mean = 57%; n = 10). After removal, GE returned toward baseline (mean % gastric retention = 51%; n = 6) (p less than 0.05) (Student's t-test). The average weight loss was 5.5 lb (n = 10; p less than 0.025). One mechanism of action of the GEGB may be delayed gastric emptying resulting in early satiety and decreased food intake with resultant weight loss.

Adult↗
PubMed1989

Localization of pheochromocytoma: MIBG [correction of MIGB], CT, and MRI correlation.

Nineteen patients (8 M, 11F) ranging in age from 15 - 67 yr old (mean = 39 yr) with clinically diagnosed pheochromocytomas were prospectively evaluated with 131I metaiodobenzyl-guanidine (MIBG) scintigraphy (n = 19), computed tomography (CT) (n = 19), and magnetic resonance imaging (MRI) (n = 17) in order to determine their relative diagnostic efficacy. Pathologic confirmation was obtained in all 19 patients: 13 intraadrenal and six extraadrenal with metastases in five (Table 1). All three imaging modalities were in agreement in 11 of 14 completed examinations (79%). MIBG and CT agreed in 16 of the 19 patients in whom both were performed (84%). MIBG/MR and CT/MR results were concordant in 12 of 14 (86%) and 13 of 14 (93%) jointly completed examinations, respectively. There was one false-negative (FN) MIBG scan, two FN CT scans, and one FN MR scan. MIBG, CT, and MRI are complementary procedures with MIBG providing more specific functional information and the latter two superior anatomic detail. MIBG scintigraphy is recommended as the initial localizing study of choice (especially for the detection of extraadrenal disease and postoperative recurrence), as a guide for CT and/or MR and specific functional confirmation of their findings. Although MRI is capable of imaging in multiple planes (without exposure to ionizing radiation or the need for i.v. contrast material) with superior contrast compared to CT, it is expensive and has poor patient cooperation. However, it may be capable of differentiating pheochromocytomas from other adrenal masses on the basis of signal characterization.

3-Iodobenzylguanidine↗
PubMed1989

The effect of meal energy content on gastric emptying.

Gastric emptying (GE) has been reported to be influenced by meal weight (grams) and composition (% carbohydrate:protein:fat) but the effect of meal energy content (kcal) on gastric emptying, independent of composition, has not been thoroughly investigated by scintigraphic techniques. In order to determine the effect of caloric content on GE, 12 normal male volunteers, ranging in age from 19-28 yr (mean = 24 yr), had GE scans (n = 32) performed with a solid meal of fixed composition (carbohydrate 40%:protein 40%:fat 20%) but varying energy content [150 kcal (n = 9), 300 kcal (n = 14), and 600 kcal (n = 9)]. Increasing the energy content of the meal of fixed composition progressively delayed gastric emptying: T1/2 = 57', 70', and 95' for 150 kcal, 300 kcal and 600 kcal, respectively (p less than 0.05; Student's t-test). Reproducibility, evaluated by performing GE scans (n = 8) on different days in the same individual (n = 4) with the same meal (300 kcal), was good (r greater than or equal to 0.89). Variability varied inversely with meal energy content (CV:150 kcal greater than or equal to 300 kcal and 600 kcal). The 300 kcal mean seems to be the best compromise since it results in less intersubject variability than 150 kcal, has minimal intrasubject variability, but is not as prohibitively large as the 600 kcal meal.

Adult↗
PubMed1989

In vitro and in vivo evaluation of [123I]IBZM: a potential CNS D-2 dopamine receptor imaging agent.

In vitro binding characteristics of a CNS dopamine D-2 receptor imaging agent, (S)-N-[(1-ethyl-2-pyrrolidinyl)] methyl-2-hydroxy-3-iodo-6-methoxybenzamide [( 125I]IBZM), was carried out in rats. Also brain images, as well as organ biodistribution were determined in a monkey following the administration of 123I-labeled compound. The S-(-)-I[125I]IBZM showed high specific dopamine D-2 receptor binding in rat striatum (Kd = 0.426 +/- 0.082 nM, Bmax = 480 +/- 22 fmol/mg of protein). Competition of various ligands for the IBZM binding displayed the following rank order of potency: spiperone greater than S(-)IBZM much greater than R(+)IBZM greater than or equal to S(-)BZM greater than dopamine greater than ketanserin greater than SCH-23390 much greater than propranolol, norepinephrine, serotonin. In vivo planar images of a monkey injected with [123I]IBZM demonstrated a high concentration in basal ganglia of brain. The ratios of activity in the basal ganglia to cerebellum and the cortex to cerebellum in monkey brain were 4.93 and 1.44, respectively, at 120 min postinjection. These preliminary results indicate that [123I]IBZM is a potentially promising imaging agent for the investigation of dopamine D-2 receptors in humans.

Animals↗
PubMed1989

Comparison of CT, MR, and PET in Alzheimer's dementia and normal aging.

We compared the findings of computed tomography (CT), magnetic resonance (MR), and positron emission tomography (PET) scans of glucose metabolism in 30 patients with clinically diagnosed Alzheimer's Disease (DAT) to those noted in 25 age-matched normal controls. Mean ratings of cortical and ventricular atrophy on CT and of metabolic abnormality on PET were significantly different (p less than 0.001 and p less than 0.0001, respectively) between two subject groups, however, there was a considerable overlap in reading of cortical atrophy. CT hypodensities were present in 17% of DAT patients and 12% of controls. MR revealed numerous additional periventricular and deep white matter signal changes. Neither hypodensities nor hyperintensities were correlated with PET abnormalities. Although, not infrequently, hypometabolic areas on PET scans corresponded to atrophic regions on anatomic images, they also occurred without such changes. Interestingly, cortical high signal intensity seen on MRI was frequently observed to be associated with areas of hypometabolism. Our results suggest that PET may be the most sensitive modality for detecting cortical involvement in DAT.

Aged↗
PubMed1989

Diagnosis of pedal osteomyelitis in diabetic patients using current scintigraphic techniques.

Seventy-seven diabetic patients with suspected osteomyelitis of the foot were evaluated by three-phase bone scintigraphy (TPBS), indium 111-labeled white blood cell scintigraphy (WBCS), roentgenography, or some combination thereof. Retrospective analysis after clinical and pathologic follow-up indicated that the sensitivity of TPBS alone in the diagnosis of osteomyelitis was 100%, with a specificity of only 38% and an accuracy of 63%; the sensitivity of WBCS alone was 100%, with a specificity of 78% and an accuracy of 87%; and the combination of TPBS and WBCS yielded a sensitivity of 100%, with a specificity of 79% and an accuracy of 87%. Roentgenography yielded a sensitivity of 69%, with a specificity of 82% and an accuracy of 76%. The results of this study demonstrate that WBCS is superior to TPBS in the diagnosis of osteomyelitis in the diabetic foot, and TPBS adds little when viewed in conjunction with WBCS. Based on our observations and because of the high prevalence of neuropathic joint disease and other causes of false-positive bone scans, we believe that WBCS alone is adequate for evaluation of suspected pedal osteomyelitis in diabetic patients, particularly when the suspected lesion is located in the tarsometatarsal region in contrast to the toe region (7% vs 44% specificity and 28% vs 69% accuracy, respectively, for TPBS in these two regions, compared with 100% vs 68% specificity and 100% vs 80% accuracy, respectively, for WBCS in the same two regions).

Adult↗
PubMed1988

Positron emission tomography in patients with glioma. A predictor of prognosis.

Positron emission tomography (PET) studies have been performed using 18-F-fluorodeoxyglucose in 29 adult subjects with primary brain tumors. Seventy-two percent of the patients were treated previously. The glucose metabolic state in the lesions was increased in 16 patients, and was normal or decreased in 13 patients. The hypermetabolic tumors tended to behave in a more malignant fashion. Patients with hypermetabolic tumors had a median survival of 7 months after PET scan, compared to 33 months for those with hypometabolic lesions. Among the high-grade glioma patients, the PET results separated them into a good prognosis group (hypometabolic, with 78% 1-year survival) and a poor prognosis group (hypermetabolic, with a 29% 1-year survival after PET). These results suggest that glucose metabolic studies may provide an independent measure of the aggressiveness of a brain tumor, and may supplement pathologic grading.

Adult↗
PubMed1988

Positron emission tomography and subcortical glucose metabolism in schizophrenia.

Our previous observation of a disturbed subcortical-to-cortical gradient of activity in schizophrenia was further elucidated by examining glucose metabolism in three subcortical structures: lenticular nucleus, caudate nucleus, and thalamus. Local cerebral glucose metabolism was determined with 18F-fluorodeoxyglucose using positron emission tomography (PET) in a sample of 20 unmedicated schizophrenics and 18 normal volunteers. Repeated evaluations were performed for 12 schizophrenics following treatment with psychotropic medications and for 11 controls. Unmedicated schizophrenics had lower cortical and caudate absolute metabolic rates. Subcortical-to-cortical ratios for the lenticular nucleus and thalamus were increased in schizophrenics compared with controls, reflecting a preservation of activity in these structures relative to decreased cortical metabolism. When patients were grouped by length of medication-free period before the initial study, there was a trend for patients who had been medication free less than 6 months to have higher subcortical ratios. However, there were no consistent effects of medication in the subsample of patients whose PET studies were repeated following treatment. The results demonstrate relative hypermetabolism in structures implicated in dopamine pathways. An understanding of the physiological significance of this finding awaits the combined measurement of metabolic activity and neuroreceptors in schizophrenics.

Adult↗
PubMed1988

Pleuroperitoneal communication in a patient with right pleural effusion and ascites diagnosed by technetium-99m sulfur colloid imaging.

A 55-year-old man with an 11-year history of intermittent right pleural effusions had continued fevers and a large right transudative pleural effusion. Minimal ascites was noted by ultrasound examination. A communication between the thorax and intraperitoneal cavity was established by radionuclide examination of the chest and abdomen. Tc-99m sulfur colloid was injected into the peritoneal cavity, and imaging at 1 and 4.5 hours confirmed passage from the peritoneal to the pleural cavity. Repeated attempts to sclerose the pleural cavity failed to decrease the transudative accumulations. The patient was subsequently treated with the placement of a LeVeen shunt.

Ascitic Fluid↗
PubMed1988

Ventilation abnormalities associated with pulmonary embolism.

A retrospective analysis of 2035 lung images performed over approximately 5 years revealed abnormal ventilation coexisting with pulmonary embolism in 18 patients. Matching ventilation perfusion defects may be associated with pulmonary embolism without infarction. In patients with a high clinical suspicion of acute pulmonary embolism and matching V/Q abnormalities, an angiogram may be necessary to definitely exclude the diagnosis.

Humans↗