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Biomedical subjects

A H Elgazzar

Publications and source records attributed to A H Elgazzar.

At least 19 recordsLinked to original sources
PubMed2005

The effect of intermittent pneumatic compression on the bone uptake of (99m)Tc-labelled methylene diphosphonate in the lower limb.

INTRODUCTION: Venous compression of the lower limbs will obstruct outflow through the deep and superficial veins, yet inflow will continue, without continual swelling of the limb. It is hypothesised that venous channels in the long bones act as collateral channels to restore outflow, and therefore general blood flow through bone will increase. Such a hemodynamic change should affect the uptake of radiopharmaceuticals by the bone, though uptake changes in themselves would not definitely indicate flow changes. The purpose of this study, therefore, was to determine whether bone uptake in the lower limb is affected by intermittent venous compression, irrespective of the mechanism involved. MATERIALS AND METHODS: The effect of intermittent pneumatic compression of the thigh and calf on the uptake of (99m)Tc-methylene diphosphonate (MDP) was studied in 24 patients. All were undergoing routine bone imaging for medical conditions that were not focused on their lower limbs, and received 1 h of the therapy at 60 mmHg on one limb only, after injection of the radiopharmaceutical. Three hours after injection the relative difference in uptake (net counts per pixel) between the two limbs was calculated. The standard imaging protocol was otherwise unchanged. RESULTS: The median differences in uptake in the intermittently compressed limb compared with the contralateral limb were +7.6% (interquartile range +3.9% to +16.0%, p<0.0005 [Wilcoxon]) for the anterior aspect of the femur; +11.7% (interquartile range +4.3% to +22.2%, p<0.0005) posterior, femur; +10.5% (interquartile range +6.5% to +13.8%, p<0.0005) anterior, tibia; +10.6% (interquartile range +5.5% to +17.6%, p<0.0005) posterior, tibia. CONCLUSION: Intermittent pneumatic compression clearly and significantly increased the uptake of (99m)Tc-MDP in long bones. These data are consistent with increases in blood flow through bone, though a direct mechanical influence on the bone cannot be excluded. This effect should be given consideration during routine therapeutic and thromboprophylactic use of intermittent compression, and if the mechanism of the uptake changes can be established, their possible clinical uses should be investigated.

Adult↗
PubMed1999

A new experimental model for partial ureteric obstruction in sheep.

This study aimed to develop a new experimental model of partial ureteric obstruction in sheep. Graded obstruction of the ureter using various sized catheters (Fr 3-8) for variable durations up to 6 weeks was performed in 19 sheep. The kidneys were studied by radionuclide diuretic renography for up to 21 weeks and had histopathological examination at the end of the experiment. Catheters of Fr 3 or Fr 5 should be used to block the ureter for a minimum of three weeks to produce sufficient functional and pathological changes to be studied. The advantages and disadvantages of this model are discussed.

Animals↗
PubMed1999

Tc-99m DMSA renal scan in first-time versus recurrent urinary tract infection-yield and patterns of abnormalities.

PURPOSE: To determine the yield and patterns of abnormalities noted by Tc-99m DMSA renal imaging in cases of first-time versus recurrent urinary tract infections (UTIs) in children. MATERIALS AND METHODS: We reviewed 101 Tc-99m DMSA studies performed for 52 first-time and 49 recurrent UTIs in 99 children during a period of 1 year. The average age of the patients was 4.4 years, and the female:male ratio was 7:1. Static images of the kidneys were acquired 2 hours after injection of Tc-99m DMSA in anterior, posterior, and right and left posterior oblique views. SPECT was performed in 9% of the cases. The studies were scored as normal or abnormal. RESULTS: The yield of abnormal scans in first-time UTIs was 22 (42%) and in recurrent UTI 27 (55%). Three categories of abnormalities were noted: 1) renal cortical defects (55% of the abnormal scans in first-time UTIs and 59% of the abnormal scans in recurrent UTIs; P = 0.40); 2) dilated pelvicalyceal system (27% of the abnormal studies in first-time UTIs and 63% of the abnormal studies in recurrent UTIs; P < 0.01); and 3) renal swelling showing disproportionate function with size (41% of the abnormal scans in first-time UTIs and 22% of the abnormal scans in recurrent UTIs; P = 0.21). CONCLUSIONS: The high yield of renal abnormalities by Tc-99m DMSA scanning emphasizes the importance of testing all cases of UTI, including patients with a first-time infection. Documentation of the pattern of abnormalities may help in planning for subsequent management of UTIs in these patients.

Adolescent↗
PubMed1999

Cyclic cystography: diagnostic yield in selected pediatric populations.

PURPOSE: To test the hypothesis that the diagnostic yield of cyclic cystography is related to the prevalence of vesicoureteral reflux (VUR) in the population being evaluated. MATERIALS AND METHODS: Two groups of children were examined prospectively: 124 with severe urinary tract infection, defined as patient hospitalization or a maximum temperature greater than 39.5 degrees C, and 135 with previously diagnosed VUR. Nuclear cystography was performed in 249 patients, and fluoroscopic cystography was performed in 10. If VUR was not seen during the first cycle of bladder filling and voiding, a second cycle was performed. RESULTS: VUR was present during cycle 1 in 40 (32%) of 124 patients with severe urinary tract infection and 90 (67%) of 135 children in the VUR follow-up group (P < .001). VUR was demonstrated during cycle 2 in seven (9%) of 76 of the severe urinary tract infection group and eight (24%) of 34 of the VUR follow-up group (P = .045). Of 15 patients with VUR during cycle 2, two had grade III VUR and 13 had grade I or II VUR. CONCLUSION: The second cycle of cyclic cystography has a higher diagnostic yield in patients undergoing VUR follow-up than in patients with severe urinary tract infection. The decision to perform a second cycle of bladder filling and voiding should take into account the pretest probability of VUR in the child being examined.

Adolescent↗
PubMed1998

Assessment of 99Tcm-tetrofosmin lung uptake: a modified method to avoid the contribution from high chest wall activity.

Evaluation of lung uptake during routine 99Tcm-tetrofosmin myocardial SPET (single photon emission tomography) studies may be hindered by substantial chest muscle uptake, particularly post-exercise. This study investigated this proposal and analysed the various components of chest activity that may add to the real lung uptake. Exercise SPET studies were performed on normal subjects using 99Tcm-tetrofosmin and compared with the results of 99Tcm-sestamibi and 201Tl studies. The chest to heart count ratio (CHR) was calculated from the anterior SPET projection and further subclassified into lung, anterior chest and posterior chest to heart ratios (LHR, AHR, PHR) from the left anterior oblique (LAO) projection. On post-exercise images, the 99Tcm-tetrofosmin CHR was significantly higher than that of 201Tl and 99Tcm-sestamibi. Both the 99Tcm-tetrofosmin AHR and PHR were higher than those of 201Tl and 99Tcm-sestamibi. However, the LHR was similar for all three radiopharmaceuticals. In contrast, the rest 99Tcm-tetrofosmin images differed little from the 201Tl and 99Tcm-sestamibi ones. Thus, 99Tcm-tetrofosmin lung uptake post-exercise should be interpreted with caution, as chest muscle uptake is higher than normal. A more accurate evaluation of 99Tcm-tetrofosmin lung uptake is achieved from the LAO projection, where the contribution from chest muscle counts is much less than in the routinely used anterior projection.

Adult↗
PubMed1996

Impact of bone scintigraphy on the clinical management of a patient with sickle cell anemia and recent chest pain.

The authors present a cases of acute chest syndrome that was originally thought to be due to pneumonia, in which bone imaging obtained 4 weeks later for knee pain showed a secondary finding of multiple rib infarcts that clarified the etiology of the patient's chest manifestations and led to a change in the management of the patient. Bone scintigraphy should be considered in the work-up of patients with sickle cell anemia and concurrent chest symptoms.

Adult↗
PubMed1996

High-resolution multi-detector SPET imaging of the paediatric spine.

We reviewed the planar and single photon emission tomographic (SPET) spine images of 69 paediatric patients aged 2-17 years referred for undiagnosed back pain. The SPET images were obtained using a triple-detector camera and ultra-high-resolution collimation. Abnormal images were rated as slightly positive (1+) or strongly positive (2+). The planar and SPET images were normal in 48 of 69 patients. Thirteen of the remaining 21 cases had negative planar imaging with positive SPET images (SPET was 2+ in 10 cases and 1+ in 3 cases). Four of the 21 cases were 1+ on planar imaging, but clearly positive (2+) on the SPET images. Three of the 21 cases had 2+ planar abnormalities, but SPET demonstrated additional uptake abnormalities. Lastly, a single case that was 2+ on the planar images was demonstrated to be artefactual by SPET. Thirty-seven sites were abnormal by SPET, including 17 pedicle/parts interarticularis (11 patients), 10 spinous process (8 patients), 8 vertebral endplate (2 patients) and 2 vertebral body (2 patients) abnormalities. Sites that were abnormal on SPET and normal on planar imaging included 10 of 17 (59%) in the pedicle/pars region, 9 of 10 (90%) in the spinous process, 1 of 2 (50%) in the vertebral body and 2 of 8 (25%) in the vertebral endplates. The improved resolution of ultra-high-resolution collimated multi-detector SPET permits visualization of a greater variety of abnormalities than was seen with earlier single-detector cameras, particularly those involving the spinous process.

Adolescent↗
PubMed1996

Indium-111-leukocyte and technetium-99m-sulfur colloid uptake in Paget's disease.

We report a case of polyostotic Paget's disease of bone that caused an unusual pattern of accumulation of 111In leukocytes that mimicked, at some sites, uptake of osteomyelitis, which was suspected in this patient. Technetium-99-m sulfur colloid scan clarified the nature of 111In-leukocyte accumulation as secondary to expanded active bone marrow uptake in some pagetic bones. Additionally, a spectrum of 111In-leukocyte and 99mTc-sulfur colloid uptake was noted in the bones involved by the disease that represented uptake by pagetic foci at different pathologic phases of disease. This case suggests that Paget's disease should be considered as a diagnostic possibility for areas of 111In-leukocyte accumulation, particularly when expanded uptake is seen. When suspected, correlation with bone marrow scan and/or standard radiographs should be obtained. Recognizing that Paget's disease can not only cause absent but also expanded bone marrow (depending on the disease stage) and consequently abnormal 111In-leukocyte uptake, should help avoid interpretational confusion.

Aged↗
PubMed1995

Multimodality imaging of osteomyelitis.

Early diagnosis of osteomyelitis continues to be a clinical problem. Multiple imaging modalities are being used for the diagnosis of osteomyelitis, but none of them is ideal for all cases. The choice of modality depends on several factors based on an understanding of the pathophysiologic aspects of different forms of osteomyelitis. After a brief introduction outlining some basic principles regarding the diagnosis of osteomyelitis, pathophysiologic aspects are reviewed. Advantages and disadvantages of each imaging modality and their applications in different forms of osteomyelitis are discussed. The use of different imaging modalities in the diagnosis of special forms of osteomyelitis, including chronic, diabetic foot, and vertebral osteomyelitis, and osteomyelitis associated with orthopedic appliances and sickle cell disease is reviewed. Taking into account the site of suspected osteomyelitis and the presence or absence of underlying pathologic changes and their nature, an algorithm summarizing the use of various imaging modalities in the diagnosis of osteomyelitis is presented.

Adult↗
PubMed1995

I-123 MIBG scintigraphy in adults. A report of clinical experience.

Thirty-one adult patients with clinical findings suggestive of pheochromocytoma were studied with I-123 MIBG. All patients had images obtained at 24 and 48 hours. Five patients had abnormal uptake proved to be because of I-123 MIBG avid tumors. The remaining 26 patients had no proven tumors and showed physiologic uptake in various organs. The 24-hour images were of high quality. In all cases, the 48-hour images contributed no significant additional information. Only in 1 patient did the 48-hour image add some certainty. Physiologic uptake was seen in the salivary glands, liver, G.I. tract, and urinary bladder in all patients (100%). Uptake was also observed in the lung and heart (90%), normal adrenal glands (32%), thyroid (29%), spleen (23%) uterus (13%), and neck muscles (6%). The authors' experience indicates that I-123 MIBG gives superior images compared to the previously used I-131 MIBG, that the optimum imaging time for adults is 18-24 hours, and that normal distribution patterns including uterine and neck muscle uptake should be familiar to physicians interpreting the studies.

3-Iodobenzylguanidine↗
PubMed1995

Diffuse Tl-201 uptake in the lungs. Etiologic classification and pattern recognition.

Diffuse Tl-201 uptake in the lungs could be because of cardiac, neoplastic, inflammatory, or interstitial lung disease. Examples from the different categories, differential diagnosis, and different patterns are presented. The authors discuss the different mechanisms of increased Tl-201 uptake in the lungs which vary according to the underlying pathology.

AIDS-Related Opportunistic Infections↗
PubMed1995

A comparative study between planar Ga-67, Tl-201 images, chest x-ray, and x-ray CT in inoperable non-small cell carcinoma of the lung.

Seventy patients with newly diagnosed, pathologically proven inoperable non-small cell lung cancer (NSCLC) had planar Ga-67, Tl-201, chest x-ray, and chest CT imaging performed. Tumor/Normal tissue background (T/B) ratio was calculated for 62 Ga-67 and 55 Tl-201 scintigraphy studies and comparisons were made between Ga-67 and Tl-201 imaging results regarding T/B ratios, site of lesion, and histologic type. The impact of the images on the initial knowledge of the extent of the tumor and on the radiotherapy (RT) planning was evaluated for each patient. For primary lesions, Ga-67 imaging results were positive in 94% (66 of 70 patients) versus 71% (50 of 70 patients) for Tl-201 scans (P < 0.005) and the T/B ratio was > 1.5 in 74% (46 of 62 patients) for Ga-67 versus 36% (20 of 55 patients) for Tl-201 (P < 0.0001). For centrally located lesions, sensitivity for Ga-67 was 100% (53 of 53 patients) versus 74% (39 of 53 patients) for Tl-201 (P < 0.0005) and the T/B ratio > 1.5 in 84% (38 of 45 patients) for Ga-67 versus 38% (15 of 40 patients) for Tl-201 (P > 0.001). For peripheral lesions, sensitivity of Ga-67 was 76% (13 of 17 patients) versus 64% (11 of 17) for Tl-201 (P > 0.05) and the T/B ratio was > 1.5 in 47% (8 of 17 patients) for Ga-67 versus 33% (5 of 15 patients) for Tl-201 (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Non-Small-Cell Lung↗
PubMed1995

Advanced fibrodysplasia ossificans progressiva.

Fibrodysplasia ossificans progressiva is a rare hereditary variant of heterotropic bone formation that is often difficult to diagnose. A bone scan of an advanced case of this condition is presented. Nuclear medicine physicians should be familiar with various aspects of this disease.

Adult↗