Efficiency of 124I radioisotope production from natural and enriched tellurium dioxide using 124Te(p,xn)124I reaction.

BACKGROUND: 124I Iodine (T[Formula: see text] = 4.18 d) is the only long-life positron emitter radioisotope of iodine that may be used for both imaging and therapy as well as for 131I dosimetry. Its physical characteristics permits taking advantages of the higher Positron Emission Tomography (PET) image quality, whereas the availability of new molecules to be targeted with 124I makes it a novel innovative radiotracer probe for a specific molecular targeting. RESULTS: In this study Monte Carlo and SRIM/TRIM modelling was applied to predict the nuclear parameters of the 124I production process in a small medical cyclotron IBA 18/9 Cyclone. The simulation production yields for 124I and the polluting radioisotopes were  calculated for the natural and enriched 124TeO2  +  Al2O3  solid targets irradiated with 14.8 MeV protons. The proton beam was degraded energetically from 18 MeV with 0.2 mm Havar foil. The 124Te(p,xn)124I reactions were taken into account in the simulations. The optimal thickness of the target material was calculated using the SRIM/TRIM and Geant4 codes. The results of the simulations were compared with the experimental data obtained for the natural TeO2 +Al2O3 target. The dry distillation technique of the 124-iodine was applied. CONCLUSIONS: The experimental efficiency for the natural Te target was better than 41% with an average thick target (>0.8 mm) yield of 1.32 MBq/µAh. Joining the Monte Carlo and experimental approaches makes it possible to optimize the methodology for the 124I production from the expensive Te enriched targets.

Respiratory Motion-Registered Isotropic Whole-Heart T2 Mapping in Patients With Acute Non-ischemic Myocardial Injury.

Background: T2 mapping is a magnetic resonance imaging technique that can be used to detect myocardial edema and inflammation. However, the focal nature of myocardial inflammation may render conventional 2D approaches suboptimal and make whole-heart isotropic 3D mapping desirable. While self-navigated 3D radial T2 mapping has been demonstrated to work well at a magnetic field strength of 3T, it results in too noisy maps at 1.5T. We therefore implemented a novel respiratory motion-resolved compressed-sensing reconstruction in order to improve the 3D T2 mapping precision and accuracy at 1.5T, and tested this in a heterogeneous patient cohort. Materials and Methods: Nine healthy volunteers and 25 consecutive patients with suspected acute non-ischemic myocardial injury (sarcoidosis, n = 19; systemic sclerosis, n = 2; acute graft rejection, n = 2, and myocarditis, n = 2) were included. The free-breathing T2 maps were acquired as three ECG-triggered T2-prepared 3D radial volumes. A respiratory motion-resolved reconstruction was followed by image registration of the respiratory states and pixel-wise T2 mapping. The resulting 3D maps were compared to routine 2D T2 maps. The T2 values of segments with and without late gadolinium enhancement (LGE) were compared in patients. Results: In the healthy volunteers, the myocardial T2 values obtained with the 2D and 3D techniques were similar (45.8 ± 1.8 vs. 46.8 ± 2.9 ms, respectively; P = 0.33). Conversely, in patients, T2 values did differ between 2D (46.7 ± 3.6 ms) and 3D techniques (50.1 ± 4.2 ms, P = 0.004). Moreover, with the 2D technique, T2 values of the LGE-positive segments were similar to those of the LGE-negative segments (T2LGE-= 46.2 ± 3.7 vs. T2LGE+ = 47.6 ± 4.1 ms; P = 0.49), whereas the 3D technique did show a significant difference (T2LGE- = 49.3 ± 6.7 vs. T2LGE+ = 52.6 ± 8.7 ms, P = 0.006). Conclusion: Respiratory motion-registered 3D radial imaging at 1.5T led to accurate isotropic 3D whole-heart T2 maps, both in the healthy volunteers and in a small patient cohort with suspected non-ischemic myocardial injury. Significantly higher T2 values were found in patients as compared to controls in 3D but not in 2D, suggestive of the technique's potential to increase the sensitivity of CMR at earlier stages of disease. Further study will be needed to demonstrate its accuracy.

Non-parametric MRI Brain Atlas for the Polish Population.

Introduction: The application of magnetic resonance imaging (MRI) to acquire detailed descriptions of the brain morphology in vivo is a driving force in brain mapping research. Most atlases are based on parametric statistics, however, the empirical results indicate that the population brain tissue distributions do not exhibit exactly a Gaussian shape. Our aim was to verify the population voxel-wise distribution of three main tissue classes: gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF), and to construct the brain templates for the Polish (Upper Silesian) healthy population with the associated non-parametric tissue probability maps (TPMs) taking into account the sex and age influence. Material and Methods: The voxel-wise distributions of these tissues were analyzed using the Shapiro-Wilk test. The non-parametric atlases were generated from 96 brains of the ethnically homogeneous, neurologically healthy, and radiologically verified group examined in a 3-Tesla MRI system. The standard parametric tissue proportion maps were also calculated for the sake of comparison. The maps were compared using the Wilcoxon signed-rank test and Kolmogorov-Smirnov test. The volumetric results segmented with the parametric and non-parametric templates were also analyzed. Results: The results confirmed that in each brain structure (regardless of the studied sub-population) the data distribution is skewed and apparently not Gaussian. The determined non-parametric and parametric templates were statistically compared, and significant differences were found between the maps obtained using both measures (the maps of GM, WM, and CSF). The impacts of applying the parametric and non-parametric TPMs on the segmentation process were also compared. The GM volumes are significantly greater when using the non-parametric atlas in the segmentation procedure, while the CSF volumes are smaller. Discussion and Conclusion: To determine the population atlases the parametric measures are uncritically and widely used. However, our findings suggest that the mean and parametric measures of such skewed distribution may not be the most appropriate summary statistic to find the best spatial representations of the structures in a standard space. The non-parametric methodology is more relevant and universal than the parametric approach in constructing the MRI brain atlases.

Whole Brain and Cranial Size Adjustments in Volumetric Brain Analyses of Sex- and Age-Related Trends.

Our goal was to determine the influence of sex, age and the head/brain size on the compartmental brain volumes in the radiologically verified healthy population (96 subjects; 54 women and 42 men) from the Upper Silesia region in Poland. The MRI examinations were done using 3T Philips Achieva with the same T1-weighted and T2-weighted protocols. The image segmentation procedures were performed with SPM (Statistical Parameter Mapping) and FSL-FIRST software. The volumes of 14 subcortical structures for the left and right hemispheres and 4 overall volumes were calculated. The General Linear Models (GLM) analysis was used with and without the Total Brain Volume (TBV) and Intracranial Volume (ICV) parameters as the covariates to study the regional vs. global brain atrophy. After the ICV/TBV adjustments, the majority of sex differences in the specific volumes of interest (VOIs) revealed to be linked to the difference in the head/brain size parameters. The analysis also confirmed the significant effect of the aging process on the brain loss. After the TBV adjustment, the age- and sex-related volumetric trends for the gray and white matter volumes were observed: the negative age dependence of the gray matter volume is more pronounced in the males, while in case of the white matter the positive age-related trend in the female group is weaker. The local losses of the left caudate nucleus and the right thalamus are more advanced than the global brain atrophy. Different head-size correction strategies are not interchangeable and may yield various volumetric results, but when used together, facilitate studies on the regional dependencies inherent to a healthy, but aging, brain.

18-Fluorodeoxy-Glucose Positron Emission Tomography- Computed Tomography (18-FDG-PET/CT) for Gross Tumor Volume (GTV) Delineation in Gastric Cancer Radiotherapy

Purpose: Evaluation of the 18-fluorodeoxy-glucose positron emission tomography-computed tomography (18-FDGPET/ CT) for gross tumor volume (GTV) delineation in gastric cancer patients undergoing radiotherapy. Methods: In this study, 29 gastric cancer patients (17 unresectable and 7 inoperable) were initially enrolled for radical chemoradiotherapy (45Gy/25 fractions + chemotherapy based on 5 fluorouracil) or radiotherapy alone (45Gy/25 fractions) with planning based on the 18-FDG-PET/CT images. Five patients were excluded due to excess blood glucose levels (1), false-negative positron emission tomography (1) and distant metastases revealed by 18-FDG-PET/CT (3). The analysis involved measurement of metabolic tumor volumes (MTVs) performed on PET/CT workstations. Different threshold levels of the standardized uptake value (SUV) and liver uptake were set to obtain MTVs. Secondly, GTVPET values were derived manually using the positron emission tomography (PET) dataset blinded to the computed tomography (CT) data. Subsequently, GTVCT values were delineated using a radiotherapy planning system based on the CT scans blinded to the PET data. The referenced GTVCT values were correlated with the GTVPET and were compared with a conformality index (CI). Results: The mean CI was 0.52 (range, 0.12-0.85). In 13/24 patients (54%), the GTVPET was larger than GTVCT, and in the remainder, GTVPET was smaller. Moreover, the cranio-caudal diameter of GTVPET in 16 cases (64%) was larger than that of GTVCT, smaller in 7 cases (29%), and unchanged in one case. Manual PET delineation (GTVPET) achieved the best correlation with GTVCT (Pearson correlation = 0.76, p <0.0001). Among the analyzed MTVs, a statistically significant correlation with GTVCT was revealed for MTV10%SUVmax (r = 0.63; p = 0.0014), MTVliv (r = 0.60; p = 0.0021), MTVSUV2.5 (r = 0.54; p = 0.0063); MTV20%SUVmax (r = 0.44; p = 0.0344); MTV30%SUVmax (r = 0.44; p = 0.0373). Conclusion: 18-FDG-PET/CT in gastric cancer radiotherapy planning may affect the GTV delineation.

Synthesis, isolation and purification of [(11)C]-choline.

[(11)C]-choline is an effective PET tracer used for imaging of neoplastic lesions and metastases of the prostate cancer. However, its production can be a challenge for manufacturers, as it has not yet been described in Polish or European pharmacopoeia. In this study the technical aspects of [(11)C]-choline production are described and detailed process parameters are provided. The quality control procedures for releasing [(11)C]-choline as solutio iniectabilis are also presented. The purity and quality of the radiopharmaceutical obtained according to the proposed method were find to be high enough to safely administrate the radiopharmaceutical to patients. Application of an automated synthesizer makes it possible to carry out the entire process of [(11)C]-choline production, isolation and purification within 20 minutes. It is crucial to maintain all aspects of the process as short as possible, since the decay half-time of carbon-11 is 20.4 minutes. The resulting radiopharmaceutical is sterile and pyrogen-free and of a high chemical, radiochemical, and radionuclide purity proved by chromatographic techniques. The yield of the process is up to 20%. [(11)C]-choline PET scanning can be used as accurate and effective diagnostic tool in all centers equipped with [(11)C]-target containing cyclotron.

Effect of furosemide administration before F-18 fluorodeoxyglucose positron emission tomography/computed tomography on urine radioactivity and detection of uterine cervical cancer.

BACKGROUND: In evaluating uterine cervical cancer with ¹8F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), there may be overlap between the FDG activity at tumor sites and nonspecific radioactivity in the urine. We evaluated the efficacy of furosemide premedication with routine hydration to obtain better contrast and less overlap between cervical cancer and the urinary bladder. MATERIAL AND METHODS: We retrospectively evaluated 166 patients who had primary or relapsed cervical cancer and underwent FDG PET/CT scanning with (133 patients) or without (33 patients) furosemide premedication (10 mg intravenous, slowly injected 30 min before the scan). We calculated bladder and tumor maximum and median standardized uptake value (SUVmax and SUVmed), and overlap between tumor and urinary activity was detected visually. RESULTS: Overlap between urinary and tumor radioactivity was observed in 8 of 133 scans (6%) in patients who receive furosemide and in 3 of 33 scans (9%) in patients who did not receive furosemide. The SUVmax and SUVmed for the bladder were significantly lower in patients who were pretreated with furosemide (SUVmax, 6.3; SUVmed, 4.6) than patients who were not pretreated with furosemide (SUVmax, 8.8 [P ≤ 0.008]; SUVmed, 6.5 [P ≤ 0.002]). The tumor SUVmax and SUVmed were similar between the patient groups. CONCLUSION: Furosemide premedication before FDG PET/CT scanning may enable improved evaluation of activity and extension of cervical cancer.

The prognostic value of tumor markers doubling times in medullary thyroid carcinoma - preliminary report.

INTRODUCTION: Calcitonin (Ct) and carcinoembrional antigen (CEA) are widely used as tumor markers for the post-operative follow-up of patients with medullary thyroid carcinoma (MTC).In patients with elevated serum Ct and CEA their dynamics can be described by calculating the doubling time (DT) - the time, they need to double the serum concentration. Previous reports concluded that the Ct and CEA DT have prognostic value in MTC patients. PATIENTS AND METHODS: We retrospectively analyzed data of 70 MTC patients with elevated serum Ct or CEA. In total, doubling times were calculated and the DT of the less favorable marker was used to stratify the patients into the low- and high-risk group with the cut-off value of 2 years. The survival analysis was performed using Cox proportional hazard method. RESULTS: The doubling time < = 2 years of the less-favorable marker had significant prognostic impact for recurrence-free survival, HR = 2.61 (1.43-4.71) and overall survival, HR = 8.99 (3.51-23.04). CONCLUSIONS: The calcitonin and carcinembrional antigen doubling times of less than two years are negative prognostic factors for MTC recurrence-free and total survival in patients with persistent or recurrent disease. They may be used as predictive factors for more intensive search of disease localization in asymptomatic hypercalcitoninemia and for therapy choice in symptomatic disease.

Reproducibility and consistency of evaluation techniques for HARDI data.

OBJECT: The reproducibility of three evaluation techniques for high angular resolution diffusion imaging (HARDI) data, the diffusion tensor model, q-ball reconstruction and spherical deconvolution, are compared. MATERIALS AND METHODS: Two healthy volunteers were measured in a 3 T MR system six times with the same measurement parameters; one subject was measured with different b-values. The data was evaluated to compare the consistency and reproducibility of reconstructed diffusion directions and anisotropy values for the three investigated diffusion evaluation techniques. The angle difference between the reconstructed main directions of diffusion for the investigated techniques was evaluated. For q-ball and spherical deconvolution the consistency of the second dominant diffusion direction was additionally examined. RESULTS: The differences between the tensor model and q-ball or spherical deconvolution in the estimated diffusion direction decrease with an increase in fractional anisotropy. Increasing the smoothing kernel in q-ball reconstruction renders the results similar to the ones from the diffusion tensor evaluation. Consistency in the reconstructed directions did increase for larger b-values. CONCLUSION: The evaluation of HARDI data in clinical conditions with q-ball or spherical deconvolution shows consistency and reproducibility similar to the diffusion tensor model, but provides valuable additional information about a second dominant direction of diffusion.

SPECT-CT fusion: a new diagnostic tool for endocrinology.

INTRODUCTION: The introduction of the DICOM format in all diagnostic imaging devices allowed co-registering SPECT, CT, MR and other types of biomedical imaging. Fusion can be performed by dedicated hybrid devices or by means of software. The fusion algorithm consists of two steps: coregistration and simultaneous visualization. Our center gradually implemented SPECT-CT fusion in clinical diagnostic work-up of several endocrinologic and oncologic diseases more than 2 years ago. MATERIAL AND METHODS: An easy and fast algorithm in terms of computational complexity of image fusion was presented and applied to 81 consecutive cases. Thirty-two patients were scheduled to SPECT-CT fusion after thyroidectomy and (131)I treatment for thyroid cancer, twelve after somatostatin receptor scintigraphy, seven after 131I MIBG therapy, six after diagnostic MIBG scintigraphy with (123)I or (131)I, three after parathyroid scintigraphy and two after bone scan. The most common indication to the fusion was the need of metabolic characterization of suspected lesions detected on CT scan. The anatomic localization of a focal uptake seen on SPECT and the evaluation of the radiometabolic therapy effect folloved. RESULTS: A variance of error level observed was a result of human factor, decision on marker's placement, respiratory movements and marker's displacement between acquisitions. However, 74% of patients in our series have fusion results classified as "very good" or "good". CONCLUSIONS: The selection of patients, the training of the personel and the cooperation with radiologists are the most important factors for a correct application and interpretation of the SPECT-CT image fusion.