ABSTRACT
The aim of the present work is to propose a protocol for quantification of (18)F-FDG activities at organ level through whole body exams with Positron Emission Tomography. They were selected patients with normal uptake or a single tumor. In the period 2004-2005, 745 patients were studied. Among then, it was selected 97 adults for the normal uptake control group. The main studies were: intestine; colon, rectum, lung, lymphoma and melanoma, liver, esophagus, gonads and breasts. For "prospective screening", it were selected 20 patients with the identical physical characteristics of the control group. For internal dosimetry, the main organs should be elected according the kinetics of (18)F-FDG, either considering normal uptake or pathologies. Absorbed doses due to Computed Tomography and F-FDG uptake were estimated. Comparisons between internal and external exposures, for the same organ, point out higher doses due to external irradiation, except for bladder and kidneys. For individual dose estimation, parameters such the effective half-life should be known and this information may be achieved by an adaptation of the routine protocol.
Subject(s)
Fluorodeoxyglucose F18/analysis , Multimodal Imaging/methods , Positron-Emission Tomography/methods , Radiometry/methods , Tomography, X-Ray Computed/methods , Adolescent , Adult , Brain/diagnostic imaging , Female , Humans , Kinetics , Male , Middle Aged , Young AdultABSTRACT
OBJECTIVE: To determine the frequency of the types of parathyroid gland hyperplasia and the sensitivity of sestamibi-(99m)Tc (MIBI) scintigraphy and ultrasonography (US) of patients with secondary hyperparathyroidism (SHPT) due to chronic renal failure. MATERIAL AND METHODS: We studied 43 patients with SHPT (26 females and 17 males with age range of 27-75 years). Blood tests were performed to determine intact parathyroid hormone (PTH), calcium and phosphorus concentration and parathyroid MIBI scintigraphy and US examinations were done, to evaluate each glandular function and structure. Nineteen of the 43 patients underwent total parathyroidectomy and 69 abnormal glands were removed at operation. The 69 abnormal and 4 normal glands from patients that underwent total thyroidectomy were studied by light microscopy. The results were compared and correlation was calculated to: weight, MIBI uptake and US results. RESULTS: All 43 patients had elevated serum PTH ranged from 400 to 4,075 pg/ml (1,868.0 +/- 975.9 and normal range 10-75 pg/ml). Serum calcium and phosphorus concentration were 10.13 +/- 2.02 mg/dl and 5.28 +/- 2.07 mg/dl respectively. Fifty eight of 69 glands from surgical resection were MIBI positive and 11 were negative, but their cellular composition and presentation were similar. Hyperplasic glands had increased number of all cell types considered (chief, oxyphil and clear) compared to the normal gland. Chief cell hyperplasia was the most frequent type (81 %) followed by oxyphil (9 %), clear (6 %) and adenomatous type (4 %). False negative results of 10 % to US and 4.6 % to scintigraphy were found. The correlation of gland weight and MIBI uptake were not significant (p = 0.09). The sensitivity of MIBI scintigraphy was 84 % and US was 72.5 %. CONCLUSIONS: The MIBI scintigraphy is a very sensitive tool for pre-operative localization of hyperplasic parathyroid gland and should be used as the first imaging method. The association of MIBI and US is recommended because increases the sensitivity for preoperative hyperplasic parathyroid glands identification.
