Biomedical subjects
Publications and source records attributed to A H Elgazzar.
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.
Heterotopic ossification is a disorder of unknown etiology characterized by bone formation in the mesenchymal tissues. It occurs most commonly in patients who have had traumatic brain injury, spinal cord injury, or joint trauma or surgery.
UNLABELLED: The purpose of this study was to evaluate the feasibility of using 99mTc-sestamibi in the assessment of pancreatic transplant. METHODS: Ten transplant recipients with a history of insulin-dependent diabetes mellitus were studied. Fourteen 99mTc-sestamibi studies were performed. Each patient was injected intravenously with 10 mCi of 99mTc-sestamibi. Two-second frames were obtained for 1 min, followed by serial dynamic and static images every 5 min for 30 min. Technetium-99m sestamibi studies, read by two nuclear medicine physicians, were correlated with clinicopathologic findings and compared to the ten 201Tl studies obtained in seven of these patients. RESULTS: On 99mTc-sestamibi images, normally functioning grafts showed adequate perfusion on the angiogram and good uptake followed by clearance on static images. Time-activity curves showed an initial upslope followed by a downslope after the initial uptake peak. The quality of 99mTc-sestamibi images was superior to those of 201Tl in five, similar in four and marginally inferior in one paired study. Technetium-99m-sestamibi was used for both flow and static images, whereas a 99mTc radiotracer angiogram was needed to accompany the 201Tl study. CONCLUSION: Our preliminary experience indicates that 99mTc-sestamibi helps evaluate pancreatic transplants and provides high count statistics, which result in better image quality and diagnostic detail. Extensive quantitative studies are being performed to further evaluate this agent's role in the clinical management of pancreatic transplant patients.
Hepatobiliary scintigraphy has proven to be a reliable noninvasive imaging modality to evaluate postoperative biliary obstruction, which is a frequent complication following biliary enteric bypass surgery. We present a case of a patient who had biliary enteric bypass surgery with a scintigraphic pattern simulating partial obstruction on a 99mTc hepatobiliary study performed with the patient in a supine position. The biliary stasis seen in the supine images disappeared almost completely when the images were repeated after 30 min in an upright position. Progressive accumulation of activity initially seen in the region of the biliary enteric anastomosis was not present 3 days later on a repeat study with the patient in an upright position, confirming that biliary stasis in this patient was due to a positional phenomenon. This case illustrates that biliary stasis may be positional in nature. Position related stasis should be a consideration when interpreting hepatobiliary scintigraphic studies in postoperative patients and when suspected, patients should be imaged in the upright position.
UNLABELLED: The presence of extensive obstructive airway disease in many patients leads to an interpretation of intermediate or indeterminate probability for pulmonary emboli using ventilation/perfusion lung scans. We observed that patients with extensive obstructive airway disease having perfusion abnormalities matching those on a single-breath xenon image usually have a normal pulmonary angiogram. This study's objective was to further assess the utility of a single-breath image in evaluating patients with extensive obstructive airway disease and abnormal perfusion studies categorized as having intermediate or indeterminate probability of pulmonary embolism in an attempt to decrease the number of nondiagnostic studies. METHODS: We studied retrospectively 33 patients with extensive obstructive airway disease, with abnormal perfusion scans and no infiltrates on chest x-ray categorized as having intermediate or indeterminate probability of pulmonary embolism. We established the presence or absence of matching ventilation and perfusion abnormalities by comparing perfusion scan and single-breath images. RESULTS: Among 25 patients with perfusion abnormalities matching the initial ventilation pattern on single-breath images, only 1 (4%) had pulmonary emboli as documented by pulmonary angiogram. Four out of the remaining 8 patients with no matching perfusion and single-breath ventilation pattern had pulmonary emboli (50%). CONCLUSION: Patients categorized by ventilation/perfusion scintigraphy as having intermediate or indeterminate probability for pulmonary emboli due to the presence of extensive obstructive airway disease can be further subclassified using single-breath images. Patients with matching perfusion and single-breath ventilation pattern should be categorized as having low probability for pulmonary embolism, regardless of the extent of the ventilation abnormalities.
UNLABELLED: The purpose of this retrospective study was to evaluate the utility of 131I as therapy for hyperthyroidism in children and to evaluate its short-term side effects. METHODS: The results of 131I therapy of hyperthyroidism were evaluated in a group of 35 pediatric patients. RESULTS: In 29 patients propylthiouracil or methimazole therapy was abandoned due to noncompliance (13), relapse or failure to control hyperthyroidism (13), vasculitis (1), neutropenia (1) or a lupus-like syndrome (1). Average treatment activity was 7.7 +/- 2.9 (s.d.) mCi, corresponding to 0.16 +/- 0.03 mCi/g. Thirty patients (86%) received a single radioiodine treatment and five (14%) were retreated. In patients who became hypothyroid after a single dose, hypothyroidism was noted within 100 days of treatment. Clinical management problems included vomiting in four patients and enuresis in four patients. Mild radiation thyroiditis occurred in one patient and nodularity was noted after therapy in two patients. CONCLUSION: Iodine-131 is effective for both initial treatment of hyperthyroidism and the treatment of medical treatment failures in pediatric patients. Awareness of vomiting and enuresis as potential management problems is crucial when using 131I in this age group. Therefore, special treatment precautions may be required.
The Schilling test is used to identify the cause of vitamin B12 malabsorption in patients with low serum vitamin B12 levels. The initial step required for vitamin B12 absorption is a process of separation from the protein complexes of food. The crystalline Co-57 vitamin B12 used in the Schilling test does not reproduce this physiologic process. Thus, a crystalline stage I Schilling test may be normal even in the face of cobalamin malabsorption. An adjunctive stage I Schilling test using Co-57 vitamin B12 bound to protein has been developed. The authors describe a patient with protein-bound vitamin B12 malabsorption whose crystalline Co-57 vitamin B12 stage I Schilling test was normal. A subsequent stage I Schilling test using Co-57 vitamin B12 bound to chicken serum revealed significant cobalamin malabsorption. A review of the history and literature of this diagnostic test using protein bound vitamin B12 is also presented.
PURPOSE: To determine 24- and 48-hour distribution of iodine-123 metaiodobenzylguanidine (MIBG) and to establish an optimized pediatric imaging protocol. MATERIALS AND METHODS: Seventy-seven I-123 MIBG scans obtained in 33 children undergoing evaluation for neural crest tumor were reviewed. RESULTS: Activity in the salivary glands, myocardium, liver, gut, and bladder was demonstrated on almost all scans. Activity was noted in the neck muscles, thyroid gland, and uninvolved adrenal gland in fewer studies. In 20 studies, abnormal uptake was present in the chest or abdomen at 24 and 48 hours, and lesion identification was improved at 48 hours in 12 studies. Detection of skeletal lesions on 14 scans was similar at 24 and 48 hours. Foci of tumor were first detected at I-123 MIBG imaging in nine studies, and in only two patients was tumor involvement initially missed on I-123 MIBG studies. CONCLUSION: Distribution of I-123 MIBG on images in children differs from that in earlier descriptions in adults. Images of the torso at 48 hours after injection are a useful adjunct in detection of lesions.
UNLABELLED: Iodine-123-metaiodobenzylguanidine (MIBG) SPECT was compared with 123I-MIBG planar imaging in 35 studies of 25 children with neural crest tumors. METHODS: Iodine-123-MIBG (0.070-0.140 mCi/kg intravenously) was followed at 24 hr by wholebody planar imaging and triple-detector, high-resolution thoraco-abdominal SPECT. At 48 hr, thoracoabdominal planar imaging was performed whenever a high-tissue background or gut activity interfered with the interpretation of the 24-hr planar images. SPECT views included a cine loop presentation of multiple volume-rendered projections. Two reviewers enumerated the number of abnormal sites on the planar and SPECT studies and rated the certainty of interpretation for each study on a scale from 0.1 (low certainty) to 1.0 (high). RESULTS: Abnormal uptake was noted on planar or SPECT imaging in 13 studies (seven patients). The average number of abnormal sites detected per study for all 35 studies was 2.7 for planar imaging and 2.9 for SPECT (p = not significant) (and 7.2 and 8.4 for planar and SPECT, respectively, for the 13 abnormal studies.) The certainty ratings for all 35 studies were 0.74 for planar studies, 0.82 for SPECT (p = 0.05, chi-square, compared with planar) and 0.86 for planar and SPECT combined (p = 0.01 compared with planar alone). On volume-rendered images, gut activity was seen as diffuse and/or linear intraluminal activity. CONCLUSION: When 123I-MIBG SPECT is used, the number of lesions detected is not increased, but there is a significant improvement in the certainty of interpretation over planar imaging.
UNLABELLED: Technetium-99m-Q3 is a myocardial imaging agent that produces prompt myocardial visualization in humans. METHODS: In 19 patients with angiographic coronary artery disease, 2 patients with no angiographic coronary artery stenosis greater than 50% of the luminal diameter and 6 healthy volunteers, exercise and resting myocardial imaging were performed with 99mTc-Q3 and also with 201Tl. Technetium-99m-Q3 imaging began 15 min after injection at rest and with exercise, in a complete imaging sequence that required less than 100 min. RESULTS: Overall accuracy for coronary disease detection was 78% (21 true-positive or true-negative studies among 27 study participants) by tomographic thallium imaging versus 89% for 99mTc-Q3 tomographic imaging (p = ns). Accuracy for detection of individual coronary stenoses was 75% (61 true-positive or true-negative coronary segment classifications among 81 total coronary segments) for 201Tl imaging and 83% for 99mTc-Q3 imaging (p = ns). CONCLUSIONS: Technetium-99m-Q3 when used in a rest-exercise sequence that can be completed in 100 min appears to provide comparable diagnostic accuracy to 201Tl for overall coronary disease detection and detection of individual coronary artery stenoses.
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Phosphorus-32, employed as the orthophosphate or polyphosphate, can reduce or relieve the pain of osteoblastic metastases without serious hematologic toxicity, especially if used as a single injection. Uptake of this beta-emitter by osteoblastic-reactive bone and possibly by tumor and other cells can lead to pain reduction and often to cell killing. Efficacy has been demonstrated for the treatment of pain in 84% of 322 breast cancer patients and 77% of 444 prostate cancer patients found in a review of the literature. These results match those of the newer radiopharmaceuticals currently under investigation.
Extracorporeal piezoelectric lithotripsy (EPL) is frequently used to treat renal calculi. We are presenting a case that developed silent ureteric obstruction following three sessions of EPL of 4,000 shocks each. The obstruction was silent and asymptomatic, and was detected 6 weeks later on a routine follow-up renogram. The obstruction was due to an impacted stone fragment in the lower ureter. After release of the obstruction, the kidney function did not return to pre-therapy levels due to irreversible damage. This case demonstrates the importance of doing renograms before and within a few days after shock therapy for renal stones.
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Complete ureteric occlusion produces various pathophysiological changes that can be monitored externally by technetium 99m diethylenetriamine penta-acetic acid (99mTc-DTPA) diuretic renography (RDR). Being a dynamic imaging study, it reflects the function of the kidneys and the urodynamics of the urinary tract. The aim of this study was to correlate the changes in parameters of RDR with the histological changes before and after the release of complete ureteric occlusion. In 9 sheep, RDR studies were performed serially after various periods of complete ureteric occlusion (up to 7 weeks) and after release of the occlusion (up to 5 weeks). The histological changes were correlated with changes in RDR. The progressive decrease in renal flow seen on renal images and flow time-activity curves (TACs) was explained by the development of endarteritis and thrombosis of small renal arteries. The progressive decrease in the renal uptake as indicated by the percentage renal uptake and the extraction slope of TAC is related to the progressive damage to the renal parenchyma, initially affecting the collecting ducts and tubules, with increasing interstitial fibrosis in the later stages. Obstruction for 3 weeks or less was associated with moderate damage to the parenchyma from which recovery was possible. Obstruction for 7 weeks was associated with marked damage without chance of recovery. The RDR is a non-invasive technique that can be used to monitor kidney damage after various periods of complete ureteric occlusion and to predict the outcome of surgery before the release of occlusion.
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Extracorporeal piezoelectric lithotripsy (EPL) has been recently introduced as a non-invasive method for treatment of renal and gall bladder stones. Thirty seven patients treated with EPL for renal calculi were the subjects of radionuclide renal studies. The aim was to evaluate the effects of EPL as a new technology by radionuclide renography. 99Tcm-DTPA and 99Tcm-DMSA studies were performed pre-EPL and one day and one week post-EPL. Various parameters of the sequential radionuclide studies were evaluated. One day post-EPL, changes in parenchymal transit time index, relative uptake function, glomerular filtration rate, time-activity curves and kidney dimensions were observed. At one week post-EPL, different parameters returned to baseline status in the majority of cases. The study indicates that EPL has a variety of effects on the kidney that could be demonstrated and followed by sequential radionuclide renal studies. Furthermore the study suggests spacing of EPL sessions by approximately one week.