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Biomedical subjects

A Alavi

Publications and source records attributed to A Alavi.

At least 55 records · Page 3Linked to original sources
PubMed2001

Similar pelvic abnormalities on FDG positron emission tomography of different origins.

Fluorodeoxyglucose positron emission tomography (FDG PET) has been used extensively to detect and stage various cancers. However, normal variation and inflammatory lesions may lead to false-positive interpretations of PET findings. The authors report three cases of increased pelvic FDG uptake with differing origins. Although the findings are similar, a postpartum uterus, lymphoma, and a bleeding uterus caused pelvic FDG uptake in these patients. Interestingly, of these three patients, the patient with lymphoma had the lowest level of FDG uptake. Clinical correlation is needed for the accurate interpretation of FDG-PET findings.

Adult↗
PubMed2001

F-18 FDG uptake in a patient with psoriatic arthritis: imaging correlation with patient symptoms.

The authors describe a patient with psoriatic arthritis in whom an increased level of F-18 fluorodeoxyglucose (F-18 FDG) uptake was seen in the joints of the hands. The areas of increased activity correlated well with the regions of symptoms reported by the patient. This case illustrates the potential use of F-18 FDG positron emission tomography to quantitatively assess the degree of arthritis activity.

Antineoplastic Agents↗
PubMed2001

FDG positron emission tomography in isolated limb perfusion therapy in patients with locally advanced melanoma: preliminary results.

PURPOSE: Isolated limb perfusion (ILP) with high-dose chemotherapy and tumor necrosis factor is being tested in clinical trials as a treatment for locally advanced extremity melanoma. The authors investigated the ability of F-18 fluorodeoxyglucose positron emission tomography (FDG PET) to determine the true extent of disease in patients with this condition, whose distribution of lesions differs from that seen in previous studies. METHODS: Nine patients with locally advanced melanoma were selected for imaging of the entire body and extremities using FDG PET from a group of participants in a clinical trial of ILP with melphalan +/- tumor necrosis factor. Scans were obtained without attenuation correction. Post-treatment scans were obtained in three patients 1 month after ILP. The findings in the FDG-PET scans were compared with those of a standard protocol (SP) that included anatomic images and physical examinations. RESULTS: Eighty lesions (74 malignant, 6 benign) were detected with FDG PET and the SP combined. Only malignant lesions were detected by both methods in the perfused limbs. Of the malignant lesions, FDG PET detected 65 lesions (sensitivity rate, 88%). In contrast, 48 lesions were detected with the SP (sensitivity rate, 65%). Twenty-six malignant lesions were seen only with FDG PET (35%), whereas nine malignant lesions were seen only with SP (12%). The six benign lesions included three false-positive mediastinal lymph nodes in one patient. The accuracy rates of FDG PET and the SP were 83% and 65%, respectively. These results are comparable to those seen in previous studies with patients who had disease confined primarily to the torso. All post-therapy FDG-PET scans showed a reduction in the number of visualized limb lesions, and diffuse uptake throughout the perfused limbs. The diffuse uptake correlated with post-therapy limb inflammation. CONCLUSIONS: Non-attenuation-corrected FDG PET is more sensitive than the SP in detecting the extent of disease in candidates for ILP. The FDG uptake associated with post-therapy inflammation may reduce the contrast resolution of this technique and must be evaluated further.

Adult↗
PubMed2001

Do high glucose levels have differential effect on FDG uptake in inflammatory and malignant disorders?

BACKGROUND: The association of hyperglycaemia with reduced fluorodeoxyglucose (FDG) uptake by tumour cells is well established. Therefore, it is standard practice that all patients must fast for at least several hours prior to FDG positron emission tomography (PET) imaging. However, the effect of hyperglycaemia on FDG uptake by inflammatory and infectious lesions is unknown. The aim of this study was to investigate this important issue. METHODS: For in vitro studies human mononuclear cells were isolated from 12 normal volunteers and FDG uptake was determined in medium containing differing concentrations of glucose. FDG uptake by human mesothelioma cells was also measured for comparison. For studies involving patients, 416 FDG PET scans of patients with confirmed malignancy (n=321) or benign lesions (n=95) were reviewed retrospectively. The relationship between serum glucose level and FDG uptake by the lesions was assessed utilizing the standardized uptake value (SUV) technique. RESULTS: In the in vitro studies, while FDG uptake by mesothelioma cells decreased as glucose concentration increased, there was no differential uptake of FDG uptake by mononuclear cells at glucose concentrations less than 250 mg x dl(-1). In clinical patients, FDG uptake by malignant lesions was slightly, but negatively affected by serum glucose level (r= -0.21, P<0.01) (glucose range 49-187 mg x dl(-1)). In contrast, FDG uptake by inflammatory lesions was positively associated with serum glucose level (r=0.43, P<0.01) (glucose range 54-215 mg x dl(-1)). DISCUSSION AND CONCLUSION: While the degree of FDG uptake is primarily influenced by the nature of the underlying lesion, serum glucose concentration appears to have a small effect on FDG uptake, which differs between malignant disorders and inflammatory processes. Our data suggest that below a certain level, elevated glucose concentration might not have a negative effect on FDG uptake in inflammatory cells, contrary to that observed in malignant disorders.

Blood Glucose↗
PubMed2001

Effect of schizophrenia on frontotemporal activity during word encoding and recognition: a PET cerebral blood flow study.

OBJECTIVE: Neuropsychological studies have shown that deficits in verbal episodic memory in schizophrenia occur primarily during encoding and retrieval stages of information processing. The current study used positron emission tomography to examine the effect of schizophrenia on change in cerebral blood flow (CBF) during these memory stages. METHOD: CBF was measured in 23 healthy comparison subjects and 23 patients with schizophrenia during four conditions: resting baseline, motor baseline, word encoding, and word recognition. The motor baseline was used as a reference that was subtracted from encoding and recognition conditions by using statistical parametric mapping. RESULTS: Patients' performance was similar to that of healthy comparison subjects. During word encoding, patients showed reduced activation of left prefrontal and superior temporal regions. Reduced left prefrontal activation in patients was also seen during word recognition, and additional differences were found in the left anterior cingulate, left mesial temporal lobe, and right thalamus. Although patients' performance was similar to that of healthy comparison subjects, left inferior prefrontal activation was associated with better performance only in the comparison subjects. CONCLUSIONS: Left frontotemporal activation during episodic encoding and retrieval, which is associated with better recognition in healthy people, is disrupted in schizophrenia despite relatively intact recognition performance and right prefrontal function. This may reflect impaired strategic use of semantic information to organize encoding and facilitate retrieval.

Adult↗
PubMed2001

Apical perfusion fraction as a predictor of short-term functional outcome following bilateral lung volume reduction surgery.

STUDY OBJECTIVES: To examine whether relative hypoperfusion to the apical one third of the lungs as determined by lung scintigraphy predicts a favorable functional outcome following bilateral lung volume reduction surgery (LVRS). METHODS: We performed a retrospective analysis of 128 patients who underwent bilateral LVRS. An apical perfusion fraction (AP%), defined as the percentage of total lung perfusion to the apical one third of both lungs, was derived for each patient by quantitative scintigraphy technique. Pulmonary function testing and 6-min walk test (6MWT) data were obtained preoperatively and 3 to 6 months postoperatively. RESULTS: The mean (+/- SD) improvement in FEV(1) was 309 +/- 240 mL, 209 +/- 293 mL, and 116 +/- 224 mL for patients with an AP% of 20%, respectively (p = 0.01, analysis of variance [ANOVA]). The likelihood of experiencing an increase in FEV(1) >or= 200 mL was 68% for those with an AP% 20%. Preoperative and postoperative 6MWT data were available for 109 of 128 patients. Improvement was 250 +/- 252 feet, 205 +/- 299 feet, and 77 +/- 200 feet for patients with AP% 20%, respectively (p = 0.04, ANOVA). While 50% of those with an AP% or= 180 feet, only 21% of those with an AP% > 20% did so. CONCLUSION: This retrospective analysis suggests that quantification of apical perfusion by nuclear scintigraphy assists in predicting the likelihood of short-term functional improvement after LVRS.

Exercise Test↗
PubMed2001

Accuracy of F-18 fluorodeoxyglucose positron emission tomography for the evaluation of malignancy in patients presenting with new lung abnormalities: a retrospective review.

STUDY OBJECTIVE: To evaluate the accuracy of positron emission tomography (PET) in determining the presence of malignancy in patients presenting with new lung findings, either as an incidental finding or after treatment of a primary carcinoma. DESIGN: A retrospective review of the PET database of our hospital from April 29, 1997, to March 20, 1999, identified 196 patients referred for the evaluation of new lung findings, either as an incidental finding or following definitive treatment of a primary carcinoma. The diagnosis of either malignancy or a benign condition was established in 71 patients. This was determined by either histopathology from biopsy, or by subsequent imaging demonstrating disease progression, resolution, or stability of the initial lung findings. RESULTS: In patients presenting with new lung findings without a history of carcinoma (n = 37), the sensitivity and specificity of PET was 95% and 82%, respectively. In this population, the negative predictive value was 93% and the positive predictive value was 86%. PET was less sensitive and specific for evaluating metastatic or recurrent disease in patients previously treated for carcinoma. In patients presenting with a previously treated primary lung cancer (n = 13), the sensitivity of PET was 70%, with a specificity of 67%. The negative predictive value was only 40% and the positive predictive value was 88% in this subset of patients. In patients with an extrapulmonary primary carcinoma presenting with new lung nodules (n = 21), the sensitivity and specificity of PET was 92% and 63%, respectively. In this population, the negative predictive value was 83% while the positive predictive value was 80%. Of the 71 total cases for which follow-up data were available, there were 5 false-negative cases and 7 false-positive cases, for an overall sensitivity of 88%, specificity of 75%, negative predictive value of 81%, and positive predictive value of 84%. CONCLUSIONS: The sensitivity of PET is highest for the evaluation of new malignancy in patients without a known primary carcinoma. PET is less sensitive for evaluating metastatic or recurrent disease.

Adult↗
PubMed2001

[Does semi-quantitative analysis of FDG-PET have any additional value in the diagnosis of mesial temporal sclerosis?].

UNLABELLED: The aim of this study was to compare qualitative visual analysis with semi-quantitative analysis in the diagnosis of mesial temporal sclerosis (MTS) using FDG-PET. METHODS: This study included 21 patients with histopathological confirmation of MTS. FDG-PET visual analysis data were based on clinical reports generated soon after the completion of the scan. FDG-PET images were semi-quantitatively analyzed using regions of interest (ROIs) in 19 slices perpendicular to the longest axis of the temporal lobe. These ROIs divided each temporal lobe into three regions (lateral, inferior and medial). An asymmetry index was calculated for each region. RESULTS: The visual analysis of the FDG-PET studies demonstrated asymmetric hypometabolism in all patients. All but 1 patient underwent standard lobectomy of the same side described as hypometabolic by the PET report. Using an asymmetry index equal or greater than 9% in at least one of the regions as a threshold, the FDG-PET semi-quantitative analysis showed significant asymmetry in 18 patients. These also matched the side of lobectomy and were confirmed as sclerotic in all but one patient (same patient as above). CONCLUSION: The semi-quantitative analysis did not provide additional information over visual interpretation in this series of patients.

Adolescent↗
PubMed2001

Staging and monitoring response to treatment in primary non-Hodgkin's lymphoma of bone marrow using (18)F-fluorodeoxyglucose positron emission tomography.

Bone marrow involvement can be found in patients with low-, intermediate-, or high-grade non-Hodgkin's lymphoma. A 40-year-old woman experienced onset of low back pain radiating into her entire right lower extremity. Plain x-rays of her right leg and computed tomography of chest, abdomen, and pelvis were unremarkable. Magnetic resonance imaging of pelvis and thighs revealed diffusely abnormal marrow signal (low T1 and high T2 weighted) in the pelvis and femora. The patient underwent (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan to evaluate the extent of her disease. The scan revealed diffuse scattered foci of abnormal FDG uptake in the bone/bone marrow, which was particularly intense in the axial bones. Bone marrow biopsy confirmed extensive involvement of the bone marrow with diffuse large B-cell lymphoma. This case report highlights the utility of FDG-PET in the detection of bone marrow involvement by aggressive lymphoma.

Adult↗
PubMed2001

The promising role of 18F-FDG PET in detecting infected lower limb prosthesis implants.

UNLABELLED: The purpose of this study was to evaluate the feasibility of using 18F-FDG and PET for the detection of infection associated with lower limb arthroplasty. METHODS: Seventy-four prostheses in 62 patients in whom infection was suspected after artificial hip or knee placement were studied with this technique. Images were obtained 60 min after an intravenous injection of FDG. The images were interpreted as positive for infection if tracer uptake was increased at the bone-prosthesis interface. A final diagnosis was made by surgical exploration or clinical follow-up for 1 y. PET results were compared with the follow-up outcome in all patients. RESULTS: The sensitivity, specificity, and accuracy of PET for detecting infection associated with knee prostheses were 90.9%, 72.0%, and 77.8%, respectively. The sensitivity, specificity, and accuracy of PET for detecting infection associated with hip prostheses were 90%, 89.3%, and 89.5%, respectively. Overall, the sensitivity was 90.5% and the specificity was 81.1% for detection of lower limb infections. CONCLUSION: FDG PET is a useful imaging modality for detecting infections associated with lower limb arthroplasty and is more accurate for detecting infections associated with hip prostheses than for detecting infections associated with knee prostheses.

Adult↗
PubMed2001

Detection of mesial temporal lobe hypoperfusion in patients with temporal lobe epilepsy by use of arterial spin labeled perfusion MR imaging.

BACKGROUND AND PURPOSE: Interictal hypometabolism has lateralizing value in cases of temporal lobe epilepsy and positive predictive value for seizure-free outcome after surgery to treat epilepsy. Alterations in regional cerebral metabolism can also be inferred from measurements of regional cerebral perfusion. The purpose of this study was to determine the feasibility of detecting cerebral blood flow (CBF) asymmetries in the mesial temporal lobes using continuous arterial spin labeling perfusion MR imaging, which is a noninvasive method for calculating regional CBF. METHODS: Twelve patients with medically refractory temporal lobe epilepsy who underwent preoperative evaluation for temporal lobectomy and 12 normal control participants were studied retrospectively. Absolute and normalized mesial temporal CBF measurements were compared between the patient and control groups. Lateralization based on a perfusion asymmetry index was compared with metabolic ((18)[F]-fluorodeoxyglucose positron emission tomography) and hippocampal volumetric asymmetry indices and with clinical lateralization. RESULTS: Mesial temporal CBF was more asymmetric in patients with temporal lobe epilepsy than in normal control participants, although asymmetric mesial temporal CBF was also found in normal participants, with the left side dominant. Ipsilateral mesial temporal CBF was significantly decreased compared with contralateral mesial temporal CBF in patients with temporal lobe epilepsy. Global CBF measurements were significantly decreased in patients compared with control participants. Asymmetry in mesial temporal blood flow in patients persisted after normalization to global CBF. Lateralization using continuous arterial spin labeling perfusion MR imaging asymmetry index significantly correlated with lateralization based on (18)[F]-fluorodeoxyglucose positron emission tomography hypometabolism, hippocampal volumes, and clinical evaluation. CONCLUSION: Continuous arterial spin labeling perfusion MR imaging can detect interictal asymmetries in mesial temporal lobe perfusion in patients with temporal lobe epilepsy. This technique is readily combined with routine structural assessment and potentially offers an inexpensive and noninvasive means of screening for asymmetries in interictal mesial temporal lobe function.

Adult↗
PubMed2001

Dual time point 18F-FDG PET imaging for differentiating malignant from inflammatory processes.

UNLABELLED: The aim of this study was to investigate the difference in the rates of FDG uptake between malignant and inflammatory cells and processes. METHODS IN VITRO STUDIES: (18)F-FDG uptake by different tumor cell lines (human mesothelioma [REN]; rat mesothelioma [II45]; mice melanoma [B18F10]; mice mesothelioma [AB12]; human myeloma [GM1500]; and human ovarian cancer [SKOV3]) and peripheral blood mononuclear cells isolated from 8 healthy human volunteers was measured 20 and 60 min after FDG was added into growth medium. Animal studies: II45 cells were implanted into the left flank of rats (n = 5) and a focal inflammatory reaction (mechanical irritation) was generated in the right flank. PET images at 45 and 90 min after injection of FDG were obtained and standardized uptake values (SUVs) were determined. Patient studies: Seventy-six patients who had dual time FDG PET scans were retrospectively analyzed. All results were expressed as the percentage change in SUV of the later time image from that of the earlier time (mean +/- SD). RESULTS IN VITRO STUDIES: Except for the SKOV3 cell line, which had only minimally increased FDG uptake (+10% +/- 26%; P > 0.3), all other tumor cell lines tested showed significantly increased FDG uptake over time (GM1500, +59% +/- 19%; B18F10, +81% +/- 15%; AB12, 93% +/- 21%; II45, +161% +/- 21%; REN, +198% +/- 48%; P < 0.01 for all). By contrast, FDG uptake in mononuclear cells was decreased in 7 of 8 donors. Animal studies: SUVs of tumors from 90-min images were significantly higher than those from 45-min images (+18% +/- 8%; P < 0.01), whereas the SUVs of inflammatory lesions decreased over time (-17% +/- 13% of the early images; P < 0.05). CLINICAL STUDIES: The SUVs of delayed images from the known malignant lesions compared with those of earlier scans increased over time (+19.18% +/- 9.58%; n = 31; P < 0.001; 95% confidence interval, 15.8%-22.6%). By contrast, the SUVs of benign lung nodules decreased slightly over time (-6.3% +/- 8.1%; n = 12; P < 0.05; 95% confidence interval, -10.9% to -1.7%). The SUV of inflammatory lesions caused by radiation therapy (+1.16% +/- 7.23%; n = 8; P > 0.05; 95% confidence interval, -3.9%-6.2%) and the lesions of painful lower limb prostheses (+4.03% +/- 11.32%; n = 25; P > 0.05; 95% confidence interval, -0.4%-8.5%) remained stable over time. CONCLUSION: These preliminary data show that dual time imaging appears to be useful in distinguishing malignant from benign lesions. Further research is necessary to confirm these results.

Aged↗
PubMed2001

18F-FDG PET in characterizing adrenal lesions detected on CT or MRI.

UNLABELLED: The purpose of this study was to evaluate the ability of (18)F-FDG PET to characterize adrenal lesions in patients with proven or suspected cancers. METHODS: A retrospective analysis was performed on 50 adrenal lesions in 41 patients, whose PET scans were done to evaluate the primary or metastatic disease. CT had shown 50 adrenal lesions in 41 patients and MRI had revealed 13 lesions in 10 patients. There were 34 patients with proven malignancy (28 lung cancer, 3 thyroid cancer, 2 colorectal cancer, and 1 lymphoma) and 7 with lung nodules. Of the 50 lesions, 18 were eventually determined to be malignant either by histopathology (n = 7) or by follow-up (n = 11). The remaining 32 lesions were proven or assumed to be benign by histopathology (n = 4) or clinical follow-up (n = 28). Unlike previously published reports, PET was interpreted as positive if the uptake was equal to or greater than that of the liver. RESULTS: No malignant lesion yielded a negative result on PET. Most lesions (13/18) showed significantly higher FDG uptake than that of the liver. In the remaining 5 lesions (2 metastases from neuroendocrine tumor, 2 early metastases, and 1 necrotic metastasis), FDG uptake was equal to or slightly higher than that of the liver. Of the 32 benign lesions, there were 2 lesions with uptake equal to or slightly higher than that of the liver, 3 with uptake less than the liver but more than the background, and 27 with uptake of the background. MRI identified 3 of the 13 lesions as false-positives but FDG PET correctly identified all 3 as benign. The other 10 adrenal lesions accurately diagnosed by MRI were also characterized by PET. FDG PET for characterization of adrenal lesions showed a sensitivity of 100%, a specificity of 94%, and an accuracy of 96%. CONCLUSION: FDG PET showed excellent diagnostic performance in differentiating adrenal lesions detected on CT or MRI. Because FDG PET has the additional advantage of evaluating the primary lesions as well as metastases, it could be cost-effective and the modality of choice for the characterization of adrenal lesions, especially in patients with malignancy.

Adrenal Gland Diseases↗
PubMed2001

Osseous stress reaction in a rower diagnosed with positron emission tomography (PET): a case report.

Back injury is one of the most frequently encountered injuries in the collegiate rower. The differential diagnosis of back pain in the competitive rower includes muscle strain, ligament/tendon injury, stress reaction, stress fracture, and a tear in the annulus fibrosis. Endurance sports, such as rowing, have an increased frequency of stress injury The diagnosis of stress reaction cannot be made with plain radiographs. Many studies have firmly established the efficacy of single photon emission computed tomography (SPECT) bone scans and magnetic resonance imaging in establishing the diagnosis of a stress reaction We present a case of a collegiate rower with mid back pain secondary to a stress reaction of the endplates of the costotransverse articulation at the T8 level diagnosed by a positive positron emission tomogram study in the setting of a negative SPECT scan.

Journal Article↗