Xavier Poullias

Clinical Impact of Nonuniform Ct-based Attenuation Correction in Brain Perfusion Spect/ct Using 99mtc-ecd

Introduction Brain perfusion SPECT is commonly used to evaluate patients with cognitive impairments. Physical limits such as attenuation compromise image quality do not allow the most accurate depiction of radionuclide distribution, and thus, application of attenuation correction (AC) has been recommended. Some reports have demonstrated discordances between the uniform (UAC) and nonuniform CT-based correction (NUAC) procedures. The aim was to study the impact of these discordances on visual interpretation and their concordance with clinical symptoms. Methods Twelve patients presenting cognitive impairments were included. Brain perfusion SPECT images were reconstructed using 2 AC methods. Qualitative image assessment was performed as uptake analysis in 21 predefined cortical ROIs for each patient. Interpretation of perfusion patterns was based on a 2-score uptake scale (normal and reduced/pathologic). Variation of uptake scores in UAC- versus NUAC-processed images and their concordance with clinical symptoms were studied. Results Normal image patterns generated by UAC and NUAC methods were found in 226 (90%) of 252 and in 201 (80%) of 252 ROIs, respectively. No difference between UAC and NUAC methods was found in posterior brain areas. However, differences were recorded in 51 (20%) of 252 ROIs, and this discordance was located in the anterior areas (frontal and temporal lobes), and evaluation changed from normal to pathological patterns using NUAC method. Two years later, patients showing frontal hypoperfusion on NUAC brain SPECT images expressed clinical frontal lobe dysfunctions. Conclusions Discordances between UAC- and NUAC-processed images impact visual analysis of brain perfusion SPECT images. The NUAC-processed images show a good concordance with clinical symptoms, suggesting that it is an accurate method to correct attenuation.

Thyroid protection before 123I-ioflupane (DaTSCAN) imaging

Dear Sir, The European Association of Nuclear Medicine (EANM) procedure guidelines for brain neurotransmission single photon emission computed tomography (SPECT) imaging using I-labelled dopamine transporter ligands (version 2) published recently [1] assist nuclear medicine practitioners in clinical practice. However, we would like to clarify one point concerning thyroid protection before injection of Ilabelled tracers. This paper [1] contains a recommendation to protect the thyroid before iodine injection by perchlorate and the authors propose a 200-mg sodium perchlorate intake (or equivalent) at least 5 min before the injection of the radiopharmaceutical. The mechanism of potassium perchlorate action is well known nowadays [2]. The perchlorate anion is a potent iodine penetration inhibitor into the thyrocytes and is in competition with iodine at the sodium-iodide symporter located in the follicle cells’ basement membrane. The peak plasma level occurs 3 h after oral drug administration. The concentration inhibition mechanism of iodine at the thyroid gland level is achieved within 30–60 min after oral administration of perchlorate and during at least 6 h. After an intravenous injection of potassium perchlorate, blockage occurs immediately after administration. In France and in some other European countries, perchlorate is marketed as “potassium perchlorate” and not as sodium perchlorate. Sodium perchlorate had been previously marketed in Germany, in the Czech Republic and in Austria in a drinkable form (Irenat®) in the concentrations of 300 mg/ml (Austria) and 326.2 mg/ml (Germany) [3]. To our knowledge, it is no longer available on the market today. The group of University Hospitals of Paris (Assistance Publique des Hôpitaux de Paris, APHP) is producing this medicament in the form of potassium perchlorate capsules (200 mg) [4]. Other forms of the same medicament are capsules containing 200 mg of potassium perchlorate marketed in Italy (Pertiroid®) and the USA (Perchloracap®). Potassium perchlorate in the injection form is not manufactured nowadays. The manufacturer’s recommendation for blocking the thyroid gland is a dose of 200–400 mg of potassium perchlorate given at least between 30 and 60 min before radiopharmaceutical administration. Therefore, we think that thyroid blockage at least 30– 60 min is necessary before all injected I-labelled tracers.

First experience DaTSCAN imaging using cadmium-zinc-telluride gamma camera SPECT.

We report our first experience of brain DaTSCAN SPECT imaging using cadmium-zinc-telluride gamma camera (CZT-GC) in 2 cases: a 64-year-old patient suffering from essential tremor and a 73-year-old patient presenting with atypical bilateral extrapyramidal syndrome. In both cases, 2 different acquisitions were performed and compared, using a double-head Anger-GC, followed immediately by a second acquisition on CZT-GC. There were no significant visual differences between images generated by different GC. Our first result suggests that DaTSCAN SPECT is feasible on CZT-GC, allowing both injected dose and acquisition time reductions without compromising image quality. This experience needs to be evaluated in larger series.

Thyroid protection before 123

Dear Sir, The European Association of Nuclear Medicine (EANM) procedure guidelines for brain neurotransmission single photon emission computed tomography (SPECT) imaging using I-labelled dopamine transporter ligands (version 2) published recently [1] assist nuclear medicine practitioners in clinical practice. However, we would like to clarify one point concerning thyroid protection before injection of Ilabelled tracers. This paper [1] contains a recommendation to protect the thyroid before iodine injection by perchlorate and the authors propose a 200-mg sodium perchlorate intake (or equivalent) at least 5 min before the injection of the radiopharmaceutical. The mechanism of potassium perchlorate action is well known nowadays [2]. The perchlorate anion is a potent iodine penetration inhibitor into the thyrocytes and is in competition with iodine at the sodium-iodide symporter located in the follicle cells’ basement membrane. The peak plasma level occurs 3 h after oral drug administration. The concentration inhibition mechanism of iodine at the thyroid gland level is achieved within 30–60 min after oral administration of perchlorate and during at least 6 h. After an intravenous injection of potassium perchlorate, blockage occurs immediately after administration. In France and in some other European countries, perchlorate is marketed as “potassium perchlorate” and not as sodium perchlorate. Sodium perchlorate had been previously marketed in Germany, in the Czech Republic and in Austria in a drinkable form (Irenat®) in the concentrations of 300 mg/ml (Austria) and 326.2 mg/ml (Germany) [3]. To our knowledge, it is no longer available on the market today. The group of University Hospitals of Paris (Assistance Publique des Hôpitaux de Paris, APHP) is producing this medicament in the form of potassium perchlorate capsules (200 mg) [4]. Other forms of the same medicament are capsules containing 200 mg of potassium perchlorate marketed in Italy (Pertiroid®) and the USA (Perchloracap®). Potassium perchlorate in the injection form is not manufactured nowadays. The manufacturer’s recommendation for blocking the thyroid gland is a dose of 200–400 mg of potassium perchlorate given at least between 30 and 60 min before radiopharmaceutical administration. Therefore, we think that thyroid blockage at least 30– 60 min is necessary before all injected I-labelled tracers.

Thyroid protection before 123 I-ioflupane (DaTSCAN) imaging

Dear Sir, The European Association of Nuclear Medicine (EANM) procedure guidelines for brain neurotransmission single photon emission computed tomography (SPECT) imaging using I-labelled dopamine transporter ligands (version 2) published recently [1] assist nuclear medicine practitioners in clinical practice. However, we would like to clarify one point concerning thyroid protection before injection of Ilabelled tracers. This paper [1] contains a recommendation to protect the thyroid before iodine injection by perchlorate and the authors propose a 200-mg sodium perchlorate intake (or equivalent) at least 5 min before the injection of the radiopharmaceutical. The mechanism of potassium perchlorate action is well known nowadays [2]. The perchlorate anion is a potent iodine penetration inhibitor into the thyrocytes and is in competition with iodine at the sodium-iodide symporter located in the follicle cells’ basement membrane. The peak plasma level occurs 3 h after oral drug administration. The concentration inhibition mechanism of iodine at the thyroid gland level is achieved within 30–60 min after oral administration of perchlorate and during at least 6 h. After an intravenous injection of potassium perchlorate, blockage occurs immediately after administration. In France and in some other European countries, perchlorate is marketed as “potassium perchlorate” and not as sodium perchlorate. Sodium perchlorate had been previously marketed in Germany, in the Czech Republic and in Austria in a drinkable form (Irenat®) in the concentrations of 300 mg/ml (Austria) and 326.2 mg/ml (Germany) [3]. To our knowledge, it is no longer available on the market today. The group of University Hospitals of Paris (Assistance Publique des Hôpitaux de Paris, APHP) is producing this medicament in the form of potassium perchlorate capsules (200 mg) [4]. Other forms of the same medicament are capsules containing 200 mg of potassium perchlorate marketed in Italy (Pertiroid®) and the USA (Perchloracap®). Potassium perchlorate in the injection form is not manufactured nowadays. The manufacturer’s recommendation for blocking the thyroid gland is a dose of 200–400 mg of potassium perchlorate given at least between 30 and 60 min before radiopharmaceutical administration. Therefore, we think that thyroid blockage at least 30– 60 min is necessary before all injected I-labelled tracers.