Nuclear medicine imaging of bone infections

The inflammation and infection of bone include a wide range of processes that can result in a reduction of function or in the complete inability of patients. Apart from the inflammation, infection is sustained by pyogenic microorganisms and results mostly in massive destruction of bones and joints. The treatment of osteomyelitis requires long and expensive medical therapies and, sometimes, surgical resection for debridement of necrotic bone or to consolidate or substitute the compromised bones and joints. Radiographs and bone cultures are the mainstays for the diagnosis but often are useless in the diagnosis of activity or relapse of infection in the lengthy management of these patients. Imaging with radiopharmaceuticals, computed tomography and magnetic resonance are also used to study secondary and chronic infections and their diffusion to soft or deep tissues. The diagnosis is quite easy in acute osteomyelitis of long bones when the structure of bone is still intact. But most cases of osteomyelitis are subacute or chronic at the onset or become chronic during their evolution because of the frequent resistance to antibiotics. In chronic osteomyelitis the structure of bones is altered by fractures, surgical interventions and as a result of bone reabsorption produced by the infection. Metallic implants and prostheses produce artefacts both in computed tomography and magnetic resonance images, and radionuclide studies should be essential in these cases. Vertebral osteomyelitis is a specific entity that can be correctly diagnosed by computed tomography or magnetic resonance imaging at the onset of symptoms but only with radionuclide imaging is it possible to assess the activity of the disease after surgical stabilization or medical therapy. The lack of comparative studies showing the accuracy of each radiopharmaceutical for the study of bone infection does not allow the best nuclear medicine techniques to be chosen in an evidence-based manner. To this end we performed a meta-analysis of peer reviewed articles published between 1984 and 2004 describing the use of nuclear medicine imaging for the study of the most frequent causes of bone infections, including prosthetic joint, peripheric post-traumatic bone infections, vertebral and sternal infections. Guidelines for the choice of the optimal radiopharmaceuticals to be used in each clinical condition and for different aims is provided

Somatostatin receptor scintigraphy using (99m)Tc-EDDA/YNIC-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 (99m)Tc-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 (99m)Tc-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, (99m)Tc(V)-DMSA, (131)I-MIBG, (99m)Tc-MDP, (111)In-DTPA-octreotide and (18)F-FDG-PET) and compared with (99m)Tc-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 (99m)Tc-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 (99m)Tc-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

Clinical indications to the use of 99mTc-EDDA/HYNIC-TOC to detect somatostatin receptor-positive neuroendocrine tumors

The aim of this study was to define, retrospectively, the utility to perform Tc-99m-EDDA/HYNIC-Tyr3-octreotide (Tc-99m-EDDA/HYNIC-TOC) scan in patients with NET. We studied 50 consecutive patients affected by different types of NET and divided in two groups. Group 1: 34 patients with known lesions in which Tc-99m-EDDA/HYNIC-TOC was performed for staging, characterisation or to choose the appropriate treatment. Group 2: 16 patients suspected of having NET or in follow up after surgery. Patients were injected with 370 MBq of Tc-99m-EDDA/HYNIC-Tyr3-octreotide and whole-body and SPET images acquired 2-3 hours after injection. Overall, 29 patients (58%) had a positive scan, with a sensitivity, specificity and accuracy of 70.3%, 76.9% and 72%, respectively (78.1%, 50% and 76.5%, in group 1 and 20%, 81.2%, 62.5% in group 2). In patients from group 1 Tc-99m-HYNIC-TOC scintigraphy showed a concordance of 68% with another imaging procedure and in 9 patients revealed a greater number of lesions. In the second group, false negative results were especially found in patients with medullary thyroid cancer with negative radiological findings and elevated calcitonin. In conclusion, Tc-99m-EDDA/HYNIC-TOC is highly indicated for in vivo histological characterization of known NET lesions, previously identified by other imaging modalities or biopsy, to plan appropriate therapy especially for patients with inoperable disease. In patients with only biochemical suspicion of NET and in those with negative markers, this scintigraphy does not significantly modify the clinical management