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Johanna Svensson

Other affiliations: Sahlgrenska University Hospital
Bio: Johanna Svensson is an academic researcher from University of Gothenburg. The author has contributed to research in topics: Image quality & Radionuclide therapy. The author has an hindex of 8, co-authored 19 publications receiving 148 citations. Previous affiliations of Johanna Svensson include Sahlgrenska University Hospital.

Papers
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Journal ArticleDOI
TL;DR: Increased serum creatinine and urea values indicated long-term renal toxicity and selective morphological changes in kidney cortex of nude mice were quantified and appeared in a dose dependent manner after injection of high amounts of [(177)Lu]-DOTATATE.

39 citations

Journal ArticleDOI
TL;DR: Combined use of D and f improved tumor-to-liver tissue differentiation compared with using D or f separately, and rendered the segmented one preferable due to lower numerical complexity and shorter computational time.
Abstract: Intravoxel incoherent motion (IVIM) shows great potential in many applications, e.g., tumor tissue characterization. To reduce image-quality demands, various IVIM analysis approaches restricted to the diffusion coefficient (D) and the perfusion fraction (f) are increasingly being employed. In this work, the impact of estimation approach for D and f is studied. Four approaches for estimating D and f were studied: segmented IVIM fitting, least-squares fitting of a simplified IVIM model (sIVIM), and Bayesian fitting of the sIVIM model using marginal posterior modes or posterior means. The estimation approaches were evaluated in terms of bias and variability as well as ability for differentiation between tumor and healthy liver tissue using simulated and in vivo data. All estimation approaches had similar variability and ability for differentiation and negligible bias, except for the Bayesian posterior mean of f, which was substantially biased. Combined use of D and f improved tumor-to-liver tissue differentiation compared with using D or f separately. The similar performance between estimation approaches renders the segmented one preferable due to lower numerical complexity and shorter computational time. Superior tissue differentiation when combining D and f suggests complementary biologically relevant information.

37 citations

Journal ArticleDOI
TL;DR: The estimated bone marrow absorbed doses by image-based techniques and the correlation with platelets are influenced by the choice of measured vertebrae and the presence of skeletal metastases.
Abstract: This study aimed to compare different image-based methods for bone marrow dosimetry and study the dose–response relationship during treatment with 177Lu-DOTATATE in patients with and without skeletal metastases. Methods: This study included 46 patients with advanced neuroendocrine tumors treated with at least 2 fractions of 177Lu-DOTATATE at Sahlgrenska University Hospital. High- and low-uptake compartments were automatically outlined in planar images collected at 2, 24, 48, and 168 h after injection. The bone marrow absorbed doses were calculated from the cross doses of the high- and low-uptake compartments and the self-dose, using the time–activity concentration curve for the low-uptake compartment. This time–activity concentration curve was adjusted using a fixed constant of 1.8 for the planar dosimetry method and using the activity concentrations in vertebral bodies in SPECT images at 24 h after injection of 177Lu-DOTATATE in 4 hybrid methods: L4-SPECT used the activity concentration in the L4 vertebra, whereas V-SPECT, L-SPECT, and T-SPECT used the median activity concentration in all visible vertebrae, lumbar vertebrae, and thoracic vertebrae, respectively. Results: Using the planar method, L4-SPECT, V-SPECT, L-SPECT, and T-SPECT, the estimated median bone marrow absorbed doses were 0.19, 0.36, 0.40, 0.39, and 0.46 Gy/7.4 GBq, respectively, with respective ranges of 0.12–0.33, 0.15–1.44, 0.19–1.71, 0.21–1.60, and 0.18–2.12 Gy/7.4 GBq. For all methods, the bone marrow absorbed dose significantly correlated with decreased platelet counts. This correlation increased after treatment fraction 2: the Spearman correlation (rs) were −0.49 for the planar method, −0.61 for L4-SPECT, −0.63 for V-SPECT, −0.63 for L-SPECT, and −0.57 for T-SPECT. A separate analysis revealed an increased correlation for patients without skeletal metastases using the planar method (rs = −0.67). In contrast, hybrid methods had poor correlations for patients without metastases and stronger correlations for patients with skeletal metastases (rs = −0.61 to −0.74). The mean bone marrow absorbed doses were 3%–69% higher for patients with skeletal metastases than for patients without. Conclusion: The estimated bone marrow absorbed doses by image-based techniques and the correlation with platelets are influenced by the choice of measured vertebrae and the presence of skeletal metastases.

35 citations

Journal ArticleDOI
TL;DR: A highly parallel Monte Carlo code for fast, ordered subset expectation maximum (OSEM) reconstructions of SPECT/CT images was developed and reconstructed patient images of 177Lu-DOTATATE treatments revealed clearly improved resolution and contrast.
Abstract: Full Monte Carlo (MC)-based SPECT reconstructions have a strong potential for correcting for image degrading factors, but the reconstruction times are long. The objective of this study was to develop a highly parallel Monte Carlo code for fast, ordered subset expectation maximum (OSEM) reconstructions of SPECT/CT images. The MC code was written in the Compute Unified Device Architecture language for a computer with four graphics processing units (GPUs) (GeForce GTX Titan X, Nvidia, USA). This enabled simulations of parallel photon emissions from the voxels matrix (1283 or 2563). Each computed tomography (CT) number was converted to attenuation coefficients for photo absorption, coherent scattering, and incoherent scattering. For photon scattering, the deflection angle was determined by the differential scattering cross sections. An angular response function was developed and used to model the accepted angles for photon interaction with the crystal, and a detector scattering kernel was used for modeling the photon scattering in the detector. Predefined energy and spatial resolution kernels for the crystal were used. The MC code was implemented in the OSEM reconstruction of clinical and phantom 177Lu SPECT/CT images. The Jaszczak image quality phantom was used to evaluate the performance of the MC reconstruction in comparison with attenuated corrected (AC) OSEM reconstructions and attenuated corrected OSEM reconstructions with resolution recovery corrections (RRC). The performance of the MC code was 3200 million photons/s. The required number of photons emitted per voxel to obtain a sufficiently low noise level in the simulated image was 200 for a 1283 voxel matrix. With this number of emitted photons/voxel, the MC-based OSEM reconstruction with ten subsets was performed within 20 s/iteration. The images converged after around six iterations. Therefore, the reconstruction time was around 3 min. The activity recovery for the spheres in the Jaszczak phantom was clearly improved with MC-based OSEM reconstruction, e.g., the activity recovery was 88% for the largest sphere, while it was 66% for AC-OSEM and 79% for RRC-OSEM. The GPU-based MC code generated an MC-based SPECT/CT reconstruction within a few minutes, and reconstructed patient images of 177Lu-DOTATATE treatments revealed clearly improved resolution and contrast.

30 citations

Journal ArticleDOI
TL;DR: Adopting SIPs for sparsely acquired projections considerably recovers image quality and could allow a reduced SPECT acquisition time in clinical dosimetry protocols.
Abstract: The aims were to decrease 177Lu-SPECT (single-photon emission computed tomography) acquisition time by reducing the number of projections and to circumvent image degradation by adding deep learning–generated synthesized projections. Methods: We constructed a deep convolutional U-structured network for generating synthetic intermediate projections (CUSIP). The number of SPECT investigations was 352 for training, 37 for validation, and 15 for testing. The input was every fourth projection of 120 acquired SPECT projections, i.e., 30 projections. The output was 30 synthetic intermediate projections (SIPs) per CUSIP. SPECT images were reconstructed with 120 or 30 projections, or 120 projections where 90 SIPs were generated from the 30 projections (30-120SIP); using 3 CUSIPs. The reconstructions were performed with two ordered subset expectation maximization (OSEM) algorithms: attenuation-corrected (AC)-OSEM, and attenuation, scatter, and collimator response–corrected (ASCC)-OSEM. Image quality of SIPs and SPECT images were quantitatively evaluated with root mean square error, peak signal-to-noise-ratio (PSNR), and structural similarity (SSIM) index metrics. From a Jaszczak SPECT Phantom, the recovery and signal-to-noise ratio (SNR) were determined. In addition, an experienced observer qualitatively assessed the SPECT image quality of the test set. Kidney activity concentrations, as determined from the different SPECT images, were compared. Results: The generated SIPs had a mean SSIM value of 0.926 (0.061). For AC-OSEM, the reconstruction with 30-120SIP had higher SSIM (0.993 vs. 0.989; p<0.001) and PSNR (49.5 vs. 47.2; p<0.001) values than the reconstruction with 30 projections. ASCC-OSEM had higher SSIM and PSNR values than AC-OSEM (p<0.001). There was a minor loss in recovery for the 30-120SIP set, but SNR was clearly improved compared to the 30-projection set. The observer assessed 27/30 of the images reconstructed with 30 projections as having unacceptable noise levels, whereas corresponding values were 2/60 for the 30-120SIP and 120 projection sets. Image quality did not differ significantly between the 30-120SIP and 120 projection reconstructions. The kidney activity concentration was similar between the different projection sets, excepting a minor reduction of 2.5% for the ASCC-OSEM 30-120SIP. Conclusion: Adopting synthetic intermediate projections for sparsely acquired projections considerably recovers image quality and could allow reduced SPECT acquisition time in clinical dosimetry protocols.

25 citations


Cited by
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Journal ArticleDOI
TL;DR: This study aimed to develop a novel AD detection system with better performance than existing systems, and observed that the pathological brain detection system is superior to latest 6 other approaches.
Abstract: Detection of Alzheimer's disease (AD) from magnetic resonance images can help neuroradiologists to make decision rapidly and avoid missing slight lesions in the brain. Currently, scholars have proposed several approaches to automatically detect AD. In this study, we aimed to develop a novel AD detection system with better performance than existing systems. 28 ADs and 98 HCs were selected from OASIS dataset. We used inter-class variance criterion to select single slice from the 3D volumetric data. Our classification system is based on three successful components: wavelet entropy, multilayer perceptron, and biogeography-base optimization. The statistical results of our method obtained an accuracy of 92.40 ± 0.83%, a sensitivity of 92.14 ± 4.39%, a specificity of 92.47 ± 1.23%. After comparison, we observed that our pathological brain detection system is superior to latest 6 other approaches.

116 citations

Journal ArticleDOI
TL;DR: A huge potential from basic biomedical research on siderophores still awaits to be utilized for clinical and translational imaging, mainly for radionuclide-based imaging.
Abstract: This review covers publications on siderophores applied for molecular imaging applications, mainly for radionuclide-based imaging. Siderophores are low molecular weight chelators produced by bacteria and fungi to scavenge essential iron. Research on these molecules has a continuing history over the past 50 years. Many biomedical applications have been developed, most prominently the use of the siderophore desferrioxamine (DFO) to tackle iron overload related diseases. Recent research described the upregulation of siderophore production and transport systems during infection. Replacing iron in siderophores by radionuclides, the most prominent Ga-68 for PET, opens approaches for targeted imaging of infection; the proof of principle has been reported for fungal infections using 68Ga-triacetylfusarinine C (TAFC). Additionally, fluorescent siderophores and therapeutic conjugates have been described and may be translated to optical imaging and theranostic applications. Siderophores have also been applied as bifunctional chelators, initially DFO as chelator for Ga-67 and more recently for Zr-89 where it has become the standard chelator in Immuno-PET. Improved DFO constructs and bifunctional chelators based on cyclic siderophores have recently been developed for Ga-68 and Zr-89 and show promising properties for radiopharmaceutical development in PET. A huge potential from basic biomedical research on siderophores still awaits to be utilized for clinical and translational imaging.

94 citations

Journal ArticleDOI
TL;DR: The preclinical application of PSMA I&T, a DOTAGA-chelated urea-based PSMA inhibitor, for SPECT/CT imaging and radionuclide therapy of prostate cancer is presented and indicates that PSMA-specific uptake in kidneys can be successfully tackled using blocking agents such as 2-PMPA.
Abstract: Prostate-specific membrane antigen (PSMA) is a well-established target for nuclear imaging and therapy of prostate cancer (PCa). Radiolabeled small-molecule PSMA inhibitors are excellent candidates for PCa theranostics-they rapidly and efficiently localize in tumor lesions. However, high tracer uptake in kidneys and salivary glands are major concerns for therapeutic applications. Here, we present the preclinical application of PSMA IT however, high renal and spleen uptake in control mice (no 2-PMPA) interfered with visualization of metastases in the vicinity of those organs. Coadministration of 2-PMPA increased the tumor-to-kidney absorbed dose ratio during (177)Lu-PSMA I&T radionuclide therapy. Hence, at equivalent absorbed dose to the tumor (36 Gy), coinjection of 2-PMPA decreased absorbed dose to the kidneys from 30 Gy to 12 Gy. Mice injected with (177)Lu-PSMA I&T only, showed signs of nephrotoxicity at 3 months after therapy, whereas mice injected with (177)Lu-PSMA I&T + 2-PMPA did not. These data indicate that PSMA I&T is a promising theranostic tool for PCa. PSMA-specific uptake in kidneys can be successfully tackled using blocking agents such as 2-PMPA.

89 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the foremost applications of artificial intelligence (AI), particularly deep learning (DL) algorithms, in single-photon emission computed tomography (SPECT) and positron emission tomography(PET) imaging.

82 citations

Journal ArticleDOI
TL;DR: A dual-tree complex wavelet transform (DTCWT) for extracting features from an image with high and reproducible accuracy rates is proposed and implemented, which demonstrate improvements in classification output when compared to that of recent studies.
Abstract: Background. Error-free diagnosis of Alzheimer’s disease (AD) from healthy control (HC) patients at an early stage of the disease is a major concern, because information about the condition’s severity and developmental risks present allows AD sufferer to take precautionary measures before irreversible brain damage occurs. Recently, there has been great interest in computer-aided diagnosis in magnetic resonance image (MRI) classification. However, distinguishing between Alzheimer’s brain data and healthy brain data in older adults (age > 60) is challenging because of their highly similar brain patterns and image intensities. Recently, cutting-edge feature extraction technologies have found extensive application in numerous fields, including medical image analysis. Here, we propose a dual-tree complex wavelet transform (DTCWT) for extracting features from an image. The dimensionality of feature vector is reduced by using principal component analysis (PCA). The reduced feature vector is sent to feed-forward neural network (FNN) to distinguish AD and HC from the input MR images. These proposed and implemented pipelines, which demonstrate improvements in classification output when compared to that of recent studies, resulted in high and reproducible accuracy rates of 90.06 ± 0.01% with a sensitivity of 92.00 ± 0.04%, a specificity of 87.78 ± 0.04%, and a precision of 89.6 ± 0.03% with 10-fold cross-validation.

79 citations