Physiopathologic atlas of thyroid scintigraphy.

Nuclear medicine is an excellent example of functional imaging. It has an established role in the evaluation and management of thyroid disorders. The physiologic and pathologic basis of radiotracer based thyroid imaging has been presented in this article. The same principles apply to the treatment of thyroid disorders using radioactive iodine.

Adapalene pretreatment increases follicular penetration of clindamycin: in vitro and in vivo studies.

BACKGROUND: Topical retinoids normalize desquamation, reduce comedogenesis and may enhance the penetration of other topicals providing more effective treatment of acne. AIM: We evaluated the effect of adapalene on skin penetration of clindamycin phosphate when it is applied concomitantly or after various time durations following adapalene application. METHODS: The in vitro studies were carried out using excised rat skin, whereas the in vivo studies were conducted on healthy human volunteers. Radioactive clindamycin phosphate (1%) gel was applied to rat skin sections and to the hands of human volunteers concomitantly and after the pretreatment of the skin for 3, 5 and 10 min with 10 mg of adapalene (0.1%) gel. Quantification of clindamycin phosphate was performed by liquid scintillation. RESULTS: In vitro skin penetration and distribution of clindamycin phosphate was affected by the pretreatment time. Significantly higher skin concentration of clindamycin phosphate (15.5%) with largest proportion in viable skin layer (9.4% of applied dose) was found when clindamycin phosphate gel was applied after the pretreatment of the skin with adapalene gel for 5 min. Further increase in pretreatment time has no additive influence on the penetration of clindamycin phosphate. In vivo results were in corroboration with the in vitro results and demonstrate significantly higher concentration of clindamycin phosphate (19%) in the skin following pretreatment with adapalene gel for 5 min. Adapalene acts as a penetration enhancer and increases the penetration of topical clindamycin phosphate. CONCLUSION: Application of clindamycin phosphate gel after the pretreatment of skin with adapalene gel for 5 min may contribute significantly to the increased efficacy of therapy.

Thyroid scintigraphy in children with hypothyroidism: a five-year experience.

The presence or absence of thyroid glandular tissue demonstrated by thyroid scintigraphy is important for genetic and prognostic counseling and for acceleration of diagnosis in other affected siblings. Technetium-99m-pertechnetate thyroid scintigraphy was performed on 27 children with cretinism at the Division of Nuclear Medicine, Faculty of Medicine Siriraj Hospital during the 5-year period from June 1991. Based on scintigraphic findings, three main groups of thyroid localization were seen. Thirteen (48.1%) were athyrotic while 3 (11.1%) had an ectopic thyroid and 11 (40.8%) had gland in normal position. Perchlorate discharge test was performed in 8 children of the last group and the results were positive indicating an organification defect. Thyroid scintigraphy and perchlorate discharge test provided the useful information for diagnosis, follow-up, and prognosis in children with cretinism.

Detection of medullary carcinoma of thyroid, with liver metastasis, using 99mTc DMSA(V) scintigraphy.

A sixty year old female referred for thyroid and liver scintigraphy had a clinical history of progressive swelling in the neck with hepatomegaly. A large cold area was detected in the right thyroid lobe using 99mTc pertechnetate and in the right lobe of liver using 99mTc phytate. Subsequent whole body scan with 99mTC DMSA(V) showed avid tracer uptake in right lobe of thyroid and liver. Aspiration cytology of thyroid and liver showed medullary carcinoma of thyroid with its metastasis in liver. Histopathology following thyroidectomy confirmed the diagnosis. Thus 99mTc pentavalent DMSA contributes specificity to diagnose medullary carcinoma of thyroid and metastatic lesions.

Functional integrity of lacrimal drainage apparatus by radionuclide dacryocystography.

30 patients with epiphora and related complaints were investigated by Radionuclide Dacrocystography. It was possible to do this procedure easily in all age groups. The site of block in the lacrimal system could be accurately determined by this non-invasive technique.

Etiology of childhood hypothyroidism.

This study prospective without any selection bias included 80 of the 152 hypothyroid infants and children seen over the past six years. The clinical diagnosis was confirmed by TSH and thyroid hormone (T3, T4) studies. Scanning for thyroid with TC99m pertechnetate was carried out in all except seven older children with grade II and III goiters where 131I uptake studies were done. Serum thyroglobulin (RIA) was estimated and antithyroglobulin and antimicrosomal antibodies were tested. Based on thyroid 131I scan or 131I uptake, 52.5% had no demonstrable thyroid tissue except one with hypoplasia (Group I, n = 42), 25% had ectopic thyroid (Group II, n = 20), and 22.5% had normal or enlarged thyroid gland (Group III, n = 18). One hypothyroid patient of Group III had thyroiditis with high antibody titre and one was proved to have iodine deficiency). The mean age at time of diagnosis was lowest in Group I (age in months--30.3 +/- 36.2; 60.6 +/- 53.9; 106.2 +/- 69.3 in Groups I, II and III respectively. The intergroup differences in age were significant. The mean serum Tg levels increased progressively from Groups I to III. In the present series thyroid dysgenesis led to hypothyroidism in 77.5%, with athyreosis in 52.5% and ectopia in 25%. Dyshormonogenesis was noted in 20% and thyroiditis in 1.5%.