Somatostatin receptor scintigraphy using <Superscript>99m</Superscript>Tc-EDDA/HYNIC-TOC in patients with medullary thyroid carcinoma

Purpose Several new somatostatin analogues have been developed for the diagnosis and therapy of different tumours. Since somatostatin receptors are often over-expressed in medullary thyroid carcinoma (MTC), the aim of our study was to evaluate the utility of scintigraphy with the somatostatin analogue ^99mTc-EDDA/HYNIC-TOC in MTC in comparison with other diagnostic techniques. Methods Forty-five patients with MTC, aged 14–83 years, were investigated. Scintigraphy using ^99mTc-EDDA/HYNIC-TOC (Tektrotyd) was performed 2 and 4 h post injection of 740 MBq (20 mCi) of the tracer. Other imaging techniques were also applied and analysed in individual cases (ultrasonography, computed tomography, ^99mTc(V)-DMSA, ¹³¹I-MIBG, ^99mTc-MDP, ¹¹¹In-DTPA-octreotide and ¹⁸F-FDG-PET) and compared with ^99mTc-EDDA/HYNIC-TOC. Results In group 1 (eight patients before thyroidectomy), uptake of the tracer was found in the primary tumours. In group 2 (six patients with remission), a false positive result was found in one patient; in the remaining five patients, no pathological foci were visualised. In group 3 (31 patients with post-surgical hypercalcitoninaemia), scintigraphy was true positive in 23 patients (74.2%): uptake in the thyroid bed was found in five patients, in the lymph nodes in 18 and in bone metastases in four. Using ^99mTc-EDDA/HYNIC-TOC scintigraphy, the overall sensitivity was 79.5%, specificity 83.3%, accuracy 80.0%, positive predictive value 96.9% and negative predictive value 38.5%. Conclusion ^99mTc-EDDA/HYNIC-TOC is clinically useful for scintigraphy in the follow-up of patients with MTC. It can be used in clinical practice for preoperative evaluation, for localisation of local recurrence or distant metastases and particularly for therapy decision making.     

Bone marrow stem cell imaging after intracoronary administration

Although feasibility and safety of autologous stem cells administration to the post-infarction heart has been proven it is not known what proportion of cells effectively do home at the damaged site. Therefore, we have labeled autologous bone marrow cells (ABMC's) by radioactive Indium and single photon emission computed tomography (SPECT) tissue distribution has been analyzed. It was detected that up to 10% of the cells were retained within the myocardium while their majority migrated or has been anchored at the spleen and liver. Comparing the number of homed cells to the total number of cells delivered one may postulate the indirect role for few hundred thousands ABMC's at heart regeneration.     

New somatostatin analogue 99mTc-HYNIC-TOC in the scintigraphic diagnosis of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) origins from parafollicular cells and secretes calcitonin. It accounts for 5-10% of malignant thyroid tumors. In MTC, radionuclide imaging is employed as complementary method in addition to the routine radiological procedures. Especially, scintigraphy using labelled peptides that specifically bind to the somatostatin receptors is used. Recently a somatostatin analogue labelled with 99mTc (99mTc-HYNIC-TOC) was synthetized. As shown in previous studies, it has favourable pharmacokinetic and clinical characteristics. Aim of this study was to evaluate the utility of 99mTc-HYNIC-TOC in the radionuclide imaging in patients in different stages of MTC. 32 patients in following stages of the disease were studied: evaluation before thyroidectomy (6 patients), remission after surgical treatment (5 patients), stagnation or recurrence after surgical therapy (21 patients). The classification was based on the calcitonin concentrations. The study group included 19 women and 13 men aged 14 to 83 years. Whole body scintigraphy was performed twice: 2 and 4 hours after injection of 20 mCi 99mTc-HYNIC-TOC using dual-head Varicam gamma camera (Elscint). The obtained results were compared to the clinical data and other employed imaging modalities. The scintigraphy using 99mTc-HYNIC-TOC showed 20 true positive, 4 true negative, 1 false positive and 7 false negative results. The sensitivity of this method was 74,1% and specificity - 80,0%. These results are better than those obtained by other authors using other imaging methods. The current study showed high utility of the new peptide tracer in the diagnosis of MTC. Its diagnostic accuracy allows us to recommend it for diagnosis and treatment planning (including radionuclide therapy) in patients with MTC on the routine basis.     

Fractionated dosage of radioiodine for the ablation of differentiated thyroid carcinoma.

In some countries with a limited number of specialized hospital beds for radionuclide therapy, ablation therapy (RIT) of differentiated thyroid carcinoma (DTC) is performed using a fractionated dosage of radioiodine. The aim of this study was to evaluate the early clinical outcome of ablation with fractionated doses of RIT in comparison to the ablation with a single dose. A subset of 386 subjects with DTC referred for the initial RIT was selected retrospectively for the study. Of these, 113 patients (29.3%) were treated with one (131)I dose of 2.2 GBq (group 1, RIT between 2001 and 2003) and 273 patients (70.7%) with fractionated doses (1.1 GBq + 1.1 GBq administered in 24 hour intervals) (group 2, RIT between 1999 and 2001). The early outcome of the initial RIT was evaluated 6-8 months later by radioiodine uptake test (RIU), thyroglobulin concentration, whole-body diagnostic scan, and neck ultrasound. On the basis of these results, the patients were classified as: CR, complete remission; NCR, no complete remission. Frequency of CR and NCR outcomes and the parameters measured during the follow-up evaluation in both groups were compared. CR outcome was found in 69 patients (61.1%) of group 1 and in 172 patients (63.0%) of group 2 (p = n.s.). No difference in measured parameters was found in both groups at the follow-up evaluation. In uncomplicated cases of DTC, RIT using a regimen of a fractionated dosage, is equally effective as the therapy with a single dose. No influence of stunning was observed in patients treated with a fractionated dosage, but the time interval between the doses was 24 hours.     

Increased uptake of technetium-99m methylene diphosphonate in muscles in the course of polymyositis

A case of a woman aged 46 years with signs of rhabdomyolysis and acute renal failure is presented. Coxsackie serum test was positive. Increased uptake of Technetium-99m methylene diphosphonate (99mTc-MDP) by muscles of thighs and calves was observed. After 1 year no increased accumulation of radiotracer in the muscles was found.