A novel approach to medical radioisotope production using inverse kinematics: A successful production test of the theranostic radionuclide 67Cu.

A novel method for the production of important medical radioisotopes has been developed. The approach is based on performing the nuclear reaction in inverse kinematics, namely sending a heavy-ion beam of appropriate energy on a light target (e.g. H, d, He) and collecting the isotope of interest. In this work, as a proof-of-concept, we studied the production of the theranostic radionuclide 67Cu (T1/2 = 62 h) via the reaction of a 70Zn beam at 15 MeV/nucleon with a hydrogen gas target. The 67Cu radionuclide alongside other coproduced isotopes, was collected after the gas target on an aluminum catcher foil and their radioactivity was measured by off-line γ-ray analysis. After 36 h post irradiation, apart from the product of interest 67Cu, the main radioimpurity coming from the 70Zn + p reaction was 69mZn (T1/2 = 13.8 h), which can be reduced by further radio-cooling. Moreover, along with the radionuclide of interest produced in inverse kinematics, the production of additional radioisotopes is possible by making use of the forward-focused neutrons from the reaction and allowing them to interact with a secondary target. A preliminary successful test of this concept was realized in the present study. The main requirement to obtain activities appropriate for preclinical studies is the development of high-intensity heavy-ion primary beams.

Interest of [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography for the diagnosis of relapse in patients with spinal infection: a prospective study.

Relapse after treatment of a spinal infection is infrequent and difficult to diagnose. The aim of this study was to assess the diagnostic performance of [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in this setting. Thirty patients (21 men, nine women; median age 61.2 years) with a suspected spinal infection relapse were prospectively included between March 2010 and June 2013. The initial diagnosis of spinal infection was confirmed by positive bacterial cultures. The patients underwent [(18)F]FDG PET/CT and magnetic resonance imaging (MRI) 1 month after antibiotic treatment interruption. PET/CT data were interpreted both visually and semi-quantitatively (SUVmax). The patients were followed for ≥12 months and the final diagnosis of relapse was based on new microbiological cultures. Seven patients relapsed during follow up. Sensitivity, specificity, positive predictive value and negative predictive value were 66.6%, 61.9%, 33.3% and 86.6%, respectively for MRI and 85.7, 82.6, 60.0 and 95.0 for PET/CT. Although these values were higher for PET/CT than for MRI, the difference was not statistically significant (p=0.3). [(18)F]FDG PET/CT may be useful for diagnosing a relapse of spinal infections, in particular if metallic implants limit the performance of MRI.

Reduced cannabinoid CB1 receptor binding in alcohol dependence measured with positron emission tomography.

Brain cannabinoid CB1 receptors contribute to alcohol-related behaviors in experimental animals, but their potential role in humans with alcohol dependence is poorly understood. We measured CB1 receptors in alcohol dependent patients in early and protracted abstinence, and in comparison with control subjects without alcohol use disorders, using positron emission tomography and [(18)F]FMPEP-d2, a radioligand for CB1 receptors. We scanned 18 male in-patients with alcohol dependence twice, within 3-7 days of admission from ongoing drinking, and after 2-4 weeks of supervised abstinence. Imaging data were compared with those from 19 age-matched healthy male control subjects. Data were also analyzed for potential influence of a common functional variation (rs2023239) in the CB1 receptor gene (CNR1) that may moderate CB1 receptor density. On the first scan, CB1 receptor binding was 20-30% lower in patients with alcohol dependence than in control subjects in all brain regions and was negatively correlated with years of alcohol abuse. After 2-4 weeks of abstinence, CB1 receptor binding remained similarly reduced in these patients. Irrespective of the diagnostic status, C allele carriers at rs2023239 had higher CB1 receptor binding compared with non-carriers. Alcohol dependence is associated with a widespread reduction of cannabinoid CB1 receptor binding in the human brain and this reduction persists at least 2-4 weeks into abstinence. The correlation of reduced binding with years of alcohol abuse suggests an involvement of CB1 receptors in alcohol dependence in humans.

Thyrotropin variations may explain some positive radioiodine therapy scans in patients with negative diagnostic scans.

UNLABELLED: Thyroglobulin (Tg) is a specific marker of residual thyroid cancer or tumor recurrence. In patients with elevated Tg levels and negative diagnostic radioiodine (131I) whole-body scans (dWBS), administration of a therapy dose may reveal foci that were not initially apparent. The aim of this study was to identify factors, other than 131I activity, which might explain why a post-therapy 131I whole-body scan is sometimes positive despite a negative dWBS. PATIENTS AND METHODS: We reviewed data on all patients with elevated Tg levels and negative dWBS with 185 MBq 131I off-T4 at followup, who subsequently received an empiric therapy dose of 3700 MBq of 131I. During a 5-yr period, 22 patients met these criteria. 131I therapy could be given immediately after negative dWBS in 9 patients, with an average of 8 extra days of hypothyroidism. In the other 13 patients, therapy was given an average of 8 months later. RESULTS: The therapy scan was negative in 16 patients, while it showed uptake in the thyroid bed in 5 patients and distant metastases in two. In the latter two patients, the TSH level was suboptimal at the time of dWBS (9 and 25 microIU/ml), and had risen to 34 and 70 microIU/ml respectively at the time of therapy. Overall, a positive scan following therapy occurred in 7 patients (6/9 patients treated immediately and 1/13 patients treated in a separate setting; p<0.01). In patients with positive therapy scans, the mean TSH level was 73 microIU/ml at the time of dWBS and 103.5 microIU/ml at the time of therapy (41% increase; p<0.05). In patients with negative therapy scans the mean TSH level was 84 microIU/ml at dWBS and 86 microIU/ml at the time of the therapy scan (2% increase). CONCLUSIONS: Our study suggests that interval increase in TSH level with a longer period of stimulation may have contributed to making the whole-body scan positive at the time of therapy. Nowadays, patients with elevated Tg are directly given a therapy dose of 131I. Special care should be taken when preparing patients who have been on suppressive levothyroxine therapy for a long time, in order to avoid misclassifying the tumor as non-functioning.

Update on the diagnosis and therapy of distant metastases of differentiated thyroid carcinoma.

Differentiated thyroid cancer, when adequately treated, has an overall good prognosis. However, 10-15% of patients develop distant metastases. The presence of metastases is an important prognostic factor that negatively affects survival. For (131)I-avid distant metastases, (131)I therapy is a very effective treatment modality that induces complete remission in about a third of patients. These figures may be even higher in case of early diagnosis, when tumor burden is still limited. Additional measures may include surgery and/or external beam radiation therapy. Cytotoxic chemotherapy is largely ineffective in patients with progressive, poorly differentiated cancer. These patients should be candidates for trials with new molecularly targeted therapeutic agents. In this paper, a review of diagnostic modalities, prognostic factors and therapeutic options for patients with distant metastases is proposed. In particular, the prognostic value of the early discovery of metastatic disease will be underlined.

Overview on the use of recombinant human thyrotropin in thyroid cancer of follicular cell origin.

Stimulation by recombinant human thyroid-stimulating hormone (rhTSH) has gained wide acceptance as an alternative to thyroid hormone withdrawal in the management of patients with differentiated thyroid cancer. RhTSH has the advantage to avoid both the clinical consequences of hypothyroidism, with a positive impact on quality of life and work productivity, and the risk of cancer growth due to the long-lasting endogenous thyrotropin stimulation. RhTSH is a heterodimeric glycoprotein produced by recombinant DNA technology that has the ability to stimulate thyroglobulin production and radioiodine uptake by thyroid cells. RhTSH is now widely used in the follow-up of thyroid cancer patients in order to improve sensitivity of thyroglobulin (Tg) measurement as well as in preparation of (131)I diagnostic whole-body scan. Although initially approved only for diagnostic purposes, rhTSH has been now approved both in Europe and in the United States for remnant ablation in low-risk patients. As far as residual or metastatic cancer treatment, rhTSH has been initially used on a compassionate need basis for elderly and frailer patients and for patients in whom the withdrawal of thyroid hormone was medically contraindicated. Nowadays, there is a trend for widening the use of rhTSH in therapy, in order to avoid hypothyroidism and the concern about the effect of prolonged endogenous thyroid-stimulating hormone stimulation on cancerous cells. Unfortunately, the studies which address the efficacy of rhTSH in cancer treatment are still scarce and the opportunity of its clinical application remains controversial. In addition, rhTSH has been shown to improve the accuracy of [(18)F]-2-fluoro-deoxy-D-glucose positron emission tomography to detect non-functioning thyroid cancer. Although all studies agree on that rhTSH is much better tolerated from the clinical point of view than thyroid hormone withdrawal, there is some controversy about its comparative ability to raise Tg levels and concentrate radioiodine in cancerous thyroid cells. The aim of this paper is to review the performances of rhTSH as compared to hypothyroidism, considering Tg stimulation and diagnostic whole-body scan sensitivity during follow-up, and its effectiveness for normal remnant ablation and for therapy of metastatic disease.