Determination of the left to right dimercaptosuccinic acid (DMSA) uptake ratio is theoretically one of the easiest quantitative procedures in nuclear medicine. The quantification can be performed on the posterior view, with or without the lateral view for correction of kidney depth. The geometric mean can also be determined using both the anterior and the posterior views. The aim of this study was to evaluate the occurrence of remarkable differences in the results from quantification of the relative renal function using the geometric mean and those obtained using the posterior counts only. Moreover, we evaluated to what extent the patient age influenced these differences. We reviewed 328 99Tcm-DMSA scans. The difference between the relative renal function obtained using the posterior view and that obtained using the geometric mean was calculated and analysed statistically. For the purpose of evaluating the value of performing the geometric mean calculation in patients of different ages, patients were divided into four age groups (group I, < or =2 years; group II, 3-9 years; group III, 10-18 years; group IV, >18 years). Using the Student's t test, no statistical differences were found in the relative renal function obtained by the two methods (posterior projection and geometric mean) in groups I (t = 0.01, P = 0.992) and II (t = 1.43, P = 0.155), which consisted of patients younger than 10 years (77% of the patients). In groups III and IV statistical differences were found (t = 2.27, P = 0.028 and t = 2.170, P = 0.038), respectively. We conclude that for children under 10 years it is unnecessary to perform depth correction using the geometric mean except in rare cases of major malformations and position anomalies.
Purpose: To evaluate the effectiveness of 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) for detecting early cancer in carriers of germline TP53 mutation, the genetic defect underlying Li-Fraumeni and related syndromes, which predisposes to many forms of cancer throughout life.Patients and methods: A total of 30 adult patients from six families with germline TP53 mutations were recruited. These patients did not have a diagnosis of cancer in the 24 months preceding the study. Anomalous concentrations from whole-body 18F-FDG-PET/CT were assessed by two independent experts. Suspicious lesions were excised and subjected to pathological examination.Results: A total of 6/30 patients showed abnormal 18F-FDG-concentration. Confirmation studies revealed three cases of cancer, including one lung cancer, one ovarian cancer, and one disseminated breast cancer. Three patients had non-malignant lesions (one Bartholin’s cyst and two cases of reactive lymph nodes).Conclusion:
18F-FDG-PET/CT is effective in detecting cancer in subjects who are asymptomatic according to current screening guidelines. These results further suggest that 18F-FDG-PET/CT is an appropriate method for surveillance of cancer risk in TP53 mutation carriers.
Parathyroid adenoma is the most common cause of primary hyperparathyroidism. Advances in surgical techniques have made it possible to excise only the affected parathyroid gland in most cases. Imaging examinations play a fundamental role in the preoperative planning of parathyroidectomy. To localize the parathyroid glands, imaging tests such as scintigraphy, ultrasound, and, more recently, four-dimensional computed tomography (4D CT). The aim of this pictorial review was to illustrate the use of the 4D CT protocol in cases of parathyroid adenoma and to determine how well it correlates with other imaging methods, in order to improve understanding of the 4D CT method.
Two radioaerosol preparations, TechneScan ® -DTPA ( 99m Tc-DTPA, 40 mCi/3 ml; IPEN-CNEN, São Paulo, SP, Brazil) and TechneScan ® -DTPA/AEROSOL ( 99m Tc-DTPA/A, 15 mCi/1.5 ml with 0.5 ml ethanol; Mallinckrodt Medical, St. Louis, MO, USA), were compared in pulmonary ventilation studies in terms of total radiocounts and clearance after inhalation. An aerosol with ethanol is supposed to better distribute the radioparticles in the lungs. Twenty normal nonsmoking volunteers (10 men and 10 women), mean age of 23.2 years (range: 20 to 35 years), were studied. Images were obtained immediately and 30, 60 and 90 min after inhalation. Total and regional counts were obtained and the clearance half-lives of both lungs were determined. There was no difference in total counts between the two types of radioaerosol at any time (mean of 188,000 cpm for male and female subjects at time zero in both aerosols). The highest count was obtained in the middle region of both lungs (P<0.001) with both preparations. The clearance half-life did not differ between aerosols (mean of ~80-88 min for male and female subjects for both aerosols). Small nonsignificant regional differences were observed. No differences between genders or between right and left lung were observed. 99m Tc-DTPA/A generated the highest output of radioaerosol. 99m Tc-DTPA with alcohol costs approximately five times more than the aerosol without alcohol. The present results show that either kind of aerosol may be adopted routinely for use in pulmonary examinations without affecting diagnosis. We suggest that the amount of 740 mBq (20 mCi) of 99m Tc-DTPA in 1.5 ml saline can be used for routine examinations resulting in reduction of costs in pulmonary ventilation studies without diagnostic impairment.
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