The quarterly journal of nuclear medicine : official publication of the Italian Association of Nuclear Medicine (AIMN) [and] the International Association of Radiopharmacology (IAR)最新文献

Specific targeting of radionuclides to neuroblastoma, a neural crest tumour occurring predominantly in young children and associated with a relatively poor prognosis, may be achieved via the metabolic route (MIBG), receptor binding (peptides) or immunological approach (antibodies). The clinical role of 131I-MIBG therapy and radioimmunotherapy in neuroblastoma is discussed. In recurrent or progressive metastatic disease after conventional treatment modalities have failed, 131I-MIBG therapy, with an overall objective response rate of 35%, is probably the best palliative treatment, as the invasiveness and toxicity of this therapy compare favourably with that of chemotherapy, immunotherapy and external beam radiotherapy. In patients presenting with inoperable stage III and IV neuroblastoma, 131I-MIBG therapy at diagnosis is at least as effective as combination chemotherapy but is associated with much less toxicity. In patients with recurrent disease 131I-MIBG therapy in combination with hyperbaric oxygen therapy proved feasible and encouraging effects on survival have been observed. Attempts to intensify the treatment in relapsed patients by combination of 131I-MIBG therapy with high dose chemotherapy and/or total body irradiation have met with considerable toxicity. Developments in MIBG therapy aiming at improving the therapeutic index are mentioned. Early results of radioimmunotherapy using 131I-UJ13A or 131I-3F8 monoclonal antibodies have shown moderate objective response and considerable side effects in patients with stage IV neuroblastoma, who had relapsed or failed conventional therapy. New developments in radioimmunotherapy of neuroblastoma include the use of chimaeric antibodies, the enhancement of tumour uptake by modulation of antigen expression or by increasing the tumour perfusion/vascularity/permeability, the use of other labels and multistep targeting techniques, e.g. using bispecific monoclonal antibodies.

Graves' ophthalmopathy is an autoimmune process initiated and maintained by antigen(s) shared by the thyroid and the orbit. A matter of argument concerns the choice of the method of treatment for Graves' hyperthyroidism when clinically evident ophthalmopathy is present. Restoration of euthyroidism appears to be beneficial for ophthalmopathy. On the other hand the continuing disease activity associated with the recurrence of hyperthyroidism appears to adversely affect the course of ophthalmopathy. For these reasons it is our opinion that in patients with Graves' hyperthyroidism and ophthalmopathy the permanent control of thyroid hyperfunction by ablation of thyroid tissue should be obtained by radioiodine therapy or thyroidectomy. The rationale for an ablative strategy is the following: i) permanent control of hyperthyroidism avoids exacerbations of eye disease associated with recurrence of hyperthyroidism; ii) hypothyroidism, which follows thyroid tissue ablation, should be regarded as a therapeutic end point rather than as an undesirable result; iii) ablation of thyroid tissue may result in the removal of both the thyroid-orbit cross-reacting antigen(s) and the major source of thyroid-autoreactive lymphocytes. The relationship between radioiodine therapy and the course of GO is a matter of controversy, and some authors have suggested that radioiodine administration may be associated with a worsening of preexisting ophthalmopathy. This was not observed when radioiodine treatment was associated with a 3-month oral course of prednisone. The development or progression of GO after radioiodine therapy might be due to the release of thyroid antigens following radiation injury and to subsequent exacerbations of autoimmune reactions directed towards antigens shared by the thyroid and the orbit. The view that radioiodine therapy may be associated with a progression of ophthalmopathy is not shared by some authors who claim that the apparent link between progression of ophthalmopathy and radioiodine therapy might simply be coincidental, reflecting the natural history of the disease. The radioiodine-associated exacerbation of eye disease might be used as an argument against the use of radioiodine therapy in patients with ophthalmopathy. We do not share this view, since the outward effects of radioiodine on eye disease can easily be prevented by concomitant administration of glucocorticoids. Glucocorticoid treatment should be limited, in our opinion, to patients with clinically evident eye disease and to those without ophthalmopathy but with other known risk factors, such as smoking.

Craniopharyngiomas are benign cystic para-hypophyseal tumors often associated with hypopituitarism and visual-field abnormalities. Their therapy by surgery and external beam radiotherapy is imperfect. The intracavitary instillation of beta-emitting colloid radiopharmaceuticals into the cysts permits the delivery of far higher radiation doses to the cyst lining than is possible by external beam radiotherapy. This technique permits destruction of the lining epithelium with resultant elimination of cyst fluid formation and cyst shrinkage in up to 80% of cases.

131I therapy is safe and effective for most Graves' disease patients. It is being used more frequently in previously restricted populations such as children, adolescents, and women of childbearing age. It affords prompt, consistent relief of hyperthyroidism, but permanent hypothyroidism ensues in almost all patients. This complication is readily diagnosed with modern in vitro assays and inexpensive, life-long replacement therapy renders the patient asymptomatic and able to resume a normal lifestyle. Recent changes in NRC requirements have further liberalized the use of 131I for Graves' disease in the USA, permitting more patients to be treated with effective outpatient therapy. The controversial role of 131I in exacerbation of GO has been further clarified and preventive measures are available.

Thyroid cancer is a rare malignancy with wide interethnic and geographic variations. In Germany thyroid carcinoma is the 13th most frequent malignancy (2.7 new cases yearly per 100,000 inhabitants). The overall temporal incidence is increasing slightly in recent years. The most common types of cancer are papillary (60-80%) and follicular cancers (10-20%). The relevant prognostic indicators are tumor stage and distant metastases. The mean survival rates in papillary thyroid cancer usually exceed 90%, whereas in follicular thyroid cancer they amount to approximately 80%. The standard treatment procedure in differentiated papillary and follicular thyroid cancer consists of total thyroidectomy followed by adjuvant ablative therapy with radioiodine. Only in papillary thyroid cancer stage pT1N0M0 lobectomy alone is considered to be appropriate. In patients with locally invasive differentiated thyroid cancers stage pT4 adjuvant percutaneous radiation therapy is a treatment option. Radioiodine therapy has to be performed under the stimulative influence of TSH. Usually TSH suppressive medication with Levothyroxine has to be withdrawn approximately 4 weeks prior to radioiodine therapy. In the future, exogenous stimulation by recombinant TSH may be used instead of thyroid hormone withdrawal. It has been proven by different studies that ablative radioiodine therapy reduces the frequency of recurrences and tumor spread in patients with thyroid cancer significantly. In patients with distant metastases, up to 50% of complete responses may be achieved with radioiodine treatment.

Both pheochromocytomas and neuroblastomas can now be identified and located with a high level of accuracy. Scintigraphy with MIBG has become an indispensable diagnostic method for defining the extent and location of many if not most pheochromocytomas. To define the stage, to document the course and to evaluate the response to therapies in patients with neuroblastoma, imaging with MIBG is now essential.

The most important features of bone scintigraphy in metabolic bone disease are its high sensitivity and its capacity to easily image the whole body. Although in the early stages of evolution bone scintigraphy may present difficulties in disease detection because of its usual discrete generalized increased uptake, as the disease progresses, bone scintigraphy has well-recognized appearances, and with the knowledge of the different patterns of abnormality its highest diagnostic value can be obtained. Currently, the main clinical value of bone scan in metabolic bone disease is the detection of focal conditions or focal complications of such generalized disease, its most common use being the detection of fractures in osteoporosis, pseudofractures in osteomalacia and the evaluation of Paget's disease.

Parathyroid scintigraphy, first proposed in the seventies, has developed an irreplaceable role in the preoperative location of enlarged parathyroid tissues. The contribution of Ferlin, who in the early eighties proposed the use of the potassium analogue 201Thallium and subtraction scintigraphy to obviate thyroid tissue interference was especially important. At the present time, this imaging modality, is widely accepted for the preoperative localization of parathyroid adenomas owing to its high accuracy and reproducibility. Various modified acquisition and processing protocols have been reported and 201Thallium still continues to be used, but other radiopharmaceuticals, such as 99mTc-methoxyisobutyl isonitrile (99mTc-MIBI) and 99mTc-tetrofosmin are now often preferred, especially because of the more favourable physical properties of the Technetium labelling. In some cases, thyroid subtraction scintigraphy can be replaced by dual phase 99mTc-methoxyisobutyl isonitrile acquisition. There is also an increasing interest in SPECT studies, which have the potential to more accurately locate the sites of adenomas and allow for detection of smaller lesions, which further increases total sensitivity and accuracy of the technique.

Bone metabolism and thus bone remodelling and bone mineral content are profoundly influenced by many hormonal and metabolic factors. This review presents the state of the art procedures for bone mineral absorptiometry and examines the interactions of endocrine and metabolic diseases and bone mineral content. Preventive and therapeutic modalities of osteoporosis are discussed in this context.