In this paper, we propose a method for denoising diffusion-weighted images (DWI) of the brain using a convolutional neural network trained on realistic, synthetic MR data. We compare our results to averaging of repeated scans, a widespread method used in clinics to improve signal-to-noise ratio of MR images. To obtain training data for transfer learning, we model, in a data-driven fashion, the effects of echo-planar imaging (EPI): Nyquist ghosting and ramp sampling. We introduce these effects to the digital phantom of brain anatomy (BrainWeb). Instead of simulating pseudo-random noise with a defined probability distribution, we perform noise scans with a brain-DWI-designed protocol to obtain realistic noise maps. We combine them with the simulated, noise-free EPI images. We also measure the Point Spread Function in a DW image of an AJR-approved geometrical phantom and inter-scan movement in a brain scan of a healthy volunteer. Their influence on image denoising and averaging of repeated images is investigated at different signal-to-noise ratio levels. Denoising performance is evaluated quantitatively using the simulated EPI images and qualitatively in real EPI DWI of the brain. We show that the application of our method allows for a significant reduction in scan time by lowering the number of repeated scans. Visual comparisons made in the acquired brain images indicate that the denoised single-repetition images are less noisy than multi-repetition averaged images. We also analyse the convolutional neural network denoiser and point out the challenges accompanying this denoising method.

Abstract Background 124I Iodine (T $$_{1/2}$$ 1 / 2 = 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.

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.

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.

1. Athanasiou A, Vanel D, Fournier L, Balleyguier C. Optical mammography; a new technique for visualizing breast lesions in women presenting non palpable BIRADS 4-5 imaging findings; preliminary results with radiologic-pathologic correlation. Cancer Imaging. 2007;7(1):34–40. https://doi.org/10.1102/1470-7.... CrossRef Google Scholar

The aim of this work was to test the most popular and essential algorithms of the intensity nonuniformity correction of the breast MRI imaging. In this type of MRI imaging, especially in the proximity of the coil, the signal is strong but also can produce some inhomogeneities. Evaluated methods of signal correction were: N3, N3FCM, N4, Nonparametric, and SPM. For testing purposes, a uniform phantom object was used to obtain test images using breast imaging MRI coil. To quantify the results, two measures were used: integral uniformity and standard deviation. For each algorithm minimum, average and maximum values of both evaluation factors have been calculated using the binary mask created for the phantom. In the result, two methods obtained the lowest values in these measures: N3FCM and N4, however, for the second method visually phantom was the most uniform after correction.

Breast tissue deformation has recently gained interest in various medical application. The recovery of large deformation caused by gravity or compression loads and image registration is non-trivial task. The need arise to estimate large breast deformation, which can mimic natural body movement caused by examinations or surgery. Finite element methods (FEM) have been widely applied in this field. In this work we present the current breast deformation modelling trend. The meaningful applications and essentials examinations are described. The modelling software and basic techniques are presented.

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 thisstudy, 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 planningbased on the 18-FDG-PET/CT images. Five patients were excluded due to excess blood glucose levels (1), false-negativepositron emission tomography (1) and distant metastases revealed by 18-FDG-PET/CT (3). The analysis involvedmeasurement of metabolic tumor volumes (MTVs) performed on PET/CT workstations. Different threshold levels ofthe standardized uptake value (SUV) and liver uptake were set to obtain MTVs. Secondly, GTVPET values were derivedmanually 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 tothe PET data. The referenced GTVCT values were correlated with the GTVPET and were compared with a conformalityindex (CI). Results: The mean CI was 0.52 (range, 0.12-0.85). In 13/24 patients (54%), the GTVPET was larger thanGTVCT, 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 analyzedMTVs, 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.

In this paper we present an analysis of relationship between the level of uptake of radio-label at the time of treatment and the level of uptake of radio-label before and after treatment. The analysis is based on correlation analysis of the tumor features. The patients had 3 examinations: before, during, and after the therapy within 1 month. The fusion of the examinations was performed and the tumors were designated. Then, 108 features were calculated. 3 features determine the tumor: maximum, minimum and average value of Standardized Uptake Value (SUV). 105 features are the texture indices indices based on histogram, histogram of sums, histogram of differences and co-occurrence matrix. The relationship between the features and the uptake levels was analyzed using the Pearson correlation. 29 features proved to be relevant for the correlation.

[(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.

Segmentation and delineation of tumour boundaries are important and difficult step in emission tomography imaging, where acquired and reconstructed images presents large noise and a blurring level. Several methods have been previously proposed and can be used in single photon emission tomography (SPECT) or positron emission tomography (PET) imaging. Some of them relies on the standard uptake value (SUV) used in PET imaging. Presented approach can be used in both (SPECT and PET) modalities and it is based on support vector machines (SVM) classification system. System has been tested on standard phantom, widely used for testing the emission tomography devices. Results are presented for two classifiers SVM and DLDA.

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.

BACKGROUND: CT scan provides information about the anatomy and morphology, may confirm whether the change is single or has multifocal character and may suggest the probability of malignancy. Due to increased metabolism, at PET examination malignant tissues usually show a greater uptake of 18F-FDG than benign changes and healthy tissue. In several cases, PET-CT is described only by a specialist in nuclear medicine without consulting a radiologist. The aim of this study is to evaluate the accuracy of PET with assessment performed by a single nuclear medicine specialist and multidisciplinary assessment by both nuclear medicine and radiology specialists. MATERIALS AND METHODS: PET-CT was performed in 58 consecutive patients referred from John Paul II Hospital in Cracow because of radiologically diagnosed solitary pulmonary nodule (SPN) with diameter > 1 cm. An histopatological specimen was obtained in 37 patients. In 17 cases PET-CT images were evaluated by a single nuclear medicine specialist (group A), while for the remaining 20 cases, the image evaluation was performed shoulder-to-shoulder by a nuclear medicine specialist and a radiologist (group B). ANALYSIS OF DATA: Overall PET sensitivity, specificity, positive and negative predictive value and accuracy were calculated on the basis of anatomopathologic results. These data were also calculated separately for groups A and B. RESULTS: The histopatologic examination demonstrated the non neoplastic character of 7/37 lesions. The sensitivity, specificity, accuracy, positive and negative predictive values for group A were 85.7%, 100%, 100%, 33.3% and 88% while for group B were 92.8%, 83.3%, 92.8%, 83.3% and 90% respectively. CONCLUSION: PET-CT is an accurate diagnostic method to assess the nature of solitary pulmonary nodules. The consultation with radiologist does not substantially affect the PET-CT diagnostic accuracy, but can lead to a higher negative predictive value.

System matrix computation for iterative reconstruction algorithms in SPECT based on direct measurements A method for system matrix calculation in the case of iterative reconstruction algorithms in SPECT was implemented and tested. Due to a complex mathematical description of the geometry of the detector set-up, we developed a method for system matrix computation that is based on direct measurements of the detector response. In this approach, the influence of the acquisition equipment on the image formation is measured directly. The objective was to obtain the best quality of reconstructed images with respect to specified measures. This is indispensable in order to be able to perform reliable quantitative analysis of SPECT images. It is also especially important in non-hybrid gamma cameras, where not all physical processes that disturb image acquisition can be easily corrected. Two experiments with an 131 I point source placed at different distances from the detector plane were performed allowing the detector response to be acquired as a function of the point source distance. An analytical Gaussian function was fitted to the acquired data in both the one- and the two-dimensional case. A cylindrical phantom filled with a water solution of 131 I containing a region of "cold" spheres as well as a uniform solution (without any spheres) was used to perform algorithm evaluation. The reconstructed images obtained by using four different of methods system matrix computation were compared with those achieved using reconstruction software implemented in the gamma camera. The contrast of the spheres and uniformity were compared for each reconstruction result and also with the ranges of those values formulated by the AAPM (American Association of Physicists in Medicine). The results show that the implementation of the OSEM (Ordered Subsets Expectation Maximization) algorithm with a one-dimensional fit to the Gaussian CDR (Collimator-Detector Response) function provides the best results in terms of adopted measures. However, the fit of the two-dimensional function also gives satisfactory results. Furthermore, the CDR function has the potential to be applied to a fully 3D OSEM implementation. The lack of the CDR in system matrix calculation results in a very noisy image that cannot be used for diagnostic purposes.

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.

Background: The aim of this study was an attempt to answer the question whether laser mammography in dense breast (classified as category 3,4 according to ACR) examination together with x-ray mammography can enhance the detection of breast cancer.Material/Method: 248 women who had undergone a CTLM examination and mammography in the Department of Radiology of Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology in the years 2005-2007 were analyzed retrospectively. In these examinations, x-ray mammography did not reveal lesions (BIRADS 1, category 3 and 4 according to ACR). An interval between CTLM and mammography did not exceed 30 days. The examination result was verified by cytology/histopathology or observation after a minimum of 12 months provided a regular result. CTLM visualizes normal and pathological blood vessels and tissues which are rich in blood, because laser rays used in CTLM (808nm) are more absorbable by hemoglobin than by the surrounding tissue, making it possible to show a malignant tumor by its accompanying angiogenesis. The result of CTLM mammography was qualified either as the presence (+) or absence (-) of angiogenesis.Results: Among 248 women, angiogenesis was discovered by CTLM in 48 cases, in the CTLM (+) Group 13/48 women were diagnosed with breast cancer, whereas 35/48 were diagnosed with benign lesions. Angiogenesis was not identified in 200 women, in the CTLM (-) group 13/200 were diagnosed finally with cancer, with 187/200 patients having no malignancy. Ultimately, in the group of 248 women (with dense breast, category 3 and 4 according to ACR), in whom x-ray mammography did not reveal malignant processes (BIRADS 1), 26 cancers were detected out of which 13 were revealed with CTLMConclusions: Computed Tomography Laser Mammography, when used as an adjunct to x-ray mammography, enhances the detection of breast cancer in women with dense breast tissue.

Monte Carlo simulations are more and more popular trend in nuclear medicine imaging. They were also widely used in radiotherapy and brachytherapy with use of more general simulation software. GATE (Geant4 Application for Tomographic Emission) is a platform developed on general Monte Carlo code designed for simulating and tracking the passage of particles through matter (Geant4) but is specifically designed for nuclear medicine imaging purposes. The aim of this work was to create and validate a model of specific gamma-camera (E.Cam DUET), used in our department, for further use in image analysis and dosimetry field, with GATE simulation platform. We have modeled in first step a point source in the air in three configurations of gamma camera (without collimator, with low-energy high-resolution (LEHR) collimator and with high-energy (HE collimator)), then we have created a phantom with three spherical sources of different sizes but with the same concentration of the radiopharmaceutical. Simulation results were compared to the measured values of the energy spectrum and images obtained on the detectors, and show a good agreement for the point source experiments and revealed some differences for the phantom studies. This results shows that some additional tests and refinements are required but also allows us to study the image degrading quality factors, such as septal penetration and to work towards eliminating them from the pictures.

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.