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Nyholm, Tufve
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Publications (10 of 85) Show all publications
Witoszynskyj, S., Andrzejewski, P., Georg, D., Hacker, M., Nyholm, T., Rausch, I. & Knaeusl, B. (2019). Attenuation correction of a flat table top for radiation therapy in hybrid PET/MR using CT- and Ge-68/Ga-68 transmission scan-based mu-maps. Physica medica (Testo stampato), 65, 76-83
Open this publication in new window or tab >>Attenuation correction of a flat table top for radiation therapy in hybrid PET/MR using CT- and Ge-68/Ga-68 transmission scan-based mu-maps
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2019 (English)In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 65, p. 76-83Article in journal (Refereed) Published
Abstract [en]

Hybrid PET/MR offers new opportunities in radiation oncology for tissue/tumour characterisation and response assessment. Attenuation correction (AC) is an important issue especially in the presence of immobilization devices and flat table tops (FTT). The goal of this study was to compare two methods of AC using CT- and Ge-68/Ga-68 transmission scan-based attenuation maps (mu-maps) for a custom-designed FTT. Measurements were performed in the mMR PET/MR and TrueV PET/CT Biograph Siemens scanners with three different phantoms, namely the Siemens MR-QA, a cubic canister and the NEMA IEC body phantom. The study revealed that the MR image quality is not hampered by the presence of the FTT. For cubic canister applying the scanner's inherent AC alone resulted in inaccuracies in PET images, with up to -4.0% underestimation of the activity. The mean NEMA sphere activity measurements without FTT, agreed within 3.5% with the respective inserted activity. Placing the FTT in the PET/MR scanner resulted in a difference to the injected activity of 4.5% when the table was not corrected for. By introducing the mu-maps the discrepancy between the used activity and the measurements decreased down to 2.6%. To improve the AC of the FTT the creation of a dedicated mu-map was necessary while the CT-based mu-map performed equally good as the source transmission scan-based one.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Attenuation correction, PET/MR, mu-Map, Radiation oncology
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-164478 (URN)10.1016/j.ejmp.2019.08.005 (DOI)000488034100012 ()31437602 (PubMedID)
Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2019-10-22Bibliographically approved
Adjeiwaah, M., Bylund, M., Lundman, J. A., Söderström, K., Zackrisson, B., Jonsson, J. H., . . . Nyholm, T. (2019). Dosimetric Impact of MRI Distortions: A Study on Head and Neck Cancers. International Journal of Radiation Oncology, Biology, Physics, 103(4), 994-1003
Open this publication in new window or tab >>Dosimetric Impact of MRI Distortions: A Study on Head and Neck Cancers
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2019 (English)In: International Journal of Radiation Oncology, Biology, Physics, ISSN 0360-3016, E-ISSN 1879-355X, Vol. 103, no 4, p. 994-1003Article in journal (Refereed) Published
Abstract [en]

Purpose: To evaluate the effect of magnetic resonance (MR) imaging (MRI) geometric distortions on head and neck radiation therapy treatment planning (RTP) for an MRI-only RTP. We also assessed the potential benefits of patient-specific shimming to reduce the magnitude of MR distortions for a 3-T scanner.

Methods and Materials: Using an in-house Matlab algorithm, shimming within entire imaging volumes and user-defined regions of interest were simulated. We deformed 21 patient computed tomography (CT) images with MR distortion fields (gradient nonlinearity and patient-induced susceptibility effects) to create distorted CT (dCT) images using bandwidths of 122 and 488 Hz/mm at 3 T. Field parameters from volumetric modulated arc therapy plans initially optimized on dCT data sets were transferred to CT data to compute a new plan. Both plans were compared to determine the impact of distortions on dose distributions.

Results: Shimming across entire patient volumes decreased the percentage of voxels with distortions of more than 2 mm from 15.4% to 2.0%. Using the user-defined region of interest (ROI) shimming strategy, (here the Planning target volume (PTV) was the chosen ROI volume) led to increased geometric for volumes outside the PTV, as such voxels within the spinal cord with geometric shifts above 2 mm increased from 11.5% to 32.3%. The worst phantom-measured residual system distortions after 3-dimensional gradient nonlinearity correction within a radial distance of 200 mm from the isocenter was 2.17 mm. For all patients, voxels with distortion shifts of more than 2 mm resulting from patient-induced susceptibility effects were 15.4% and 0.0% using bandwidths of 122 Hz/mm and 488 Hz/mm at 3 T. Dose differences between dCT and CT treatment plans in D-50 at the planning target volume were 0.4% +/- 0.6% and 0.3% +/- 0.5% at 122 and 488 Hz/mm, respectively.

Conclusions: The overall effect of MRI geometric distortions on data used for RTP was minimal. Shimming over entire imaging volumes decreased distortions, but user-defined subvolume shimming introduced significant errors in nearby organs and should probably be avoided.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-157192 (URN)10.1016/j.ijrobp.2018.11.037 (DOI)000459153600031 ()30496879 (PubMedID)
Available from: 2019-04-15 Created: 2019-04-15 Last updated: 2019-10-31Bibliographically approved
Fetty, L., Kuess, P., Nesvacil, N., Nyholm, T., Georg, D. & Furtado, H. (2019). Evaluating different generator networks of a conditional generative adversarial network. Paper presented at 38th Annual Meeting of the European-Society-for-Radiotherapy-and-Oncology (ESTRO), Milan, ITALY, April 26-30, 2019. Radiotherapy and Oncology, 133, S555-S555
Open this publication in new window or tab >>Evaluating different generator networks of a conditional generative adversarial network
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2019 (English)In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 133, p. S555-S555Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-160314 (URN)10.1016/S0167-8140(19)31425-2 (DOI)000468315602270 ()
Conference
38th Annual Meeting of the European-Society-for-Radiotherapy-and-Oncology (ESTRO), Milan, ITALY, April 26-30, 2019
Available from: 2019-06-17 Created: 2019-06-17 Last updated: 2019-06-17Bibliographically approved
Löfstedt, T., Brynolfsson, P., Nyholm, T. & Garpebring, A. (2019). Gray-level invariant Haralick texture features. PLoS ONE, 14(2), Article ID e0212110.
Open this publication in new window or tab >>Gray-level invariant Haralick texture features
2019 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, no 2, article id e0212110Article in journal (Refereed) Published
Abstract [en]

Haralick texture features are common texture descriptors in image analysis. To compute the Haralick features, the image gray-levels are reduced, a process called quantization. The resulting features depend heavily on the quantization step, so Haralick features are not reproducible unless the same quantization is performed. The aim of this work was to develop Haralick features that are invariant to the number of quantization gray-levels. By redefining the gray-level co-occurrence matrix (GLCM) as a discretized probability density function, it becomes asymptotically invariant to the quantization. The invariant and original features were compared using logistic regression classification to separate two classes based on the texture features. Classifiers trained on the invariant features showed higher accuracies, and had similar performance when training and test images had very different quantizations. In conclusion, using the invariant Haralick features, an image pattern will give the same texture feature values independent of image quantization.

Place, publisher, year, edition, pages
Public Library of Science, 2019
National Category
Medical Biotechnology
Identifiers
urn:nbn:se:umu:diva-134995 (URN)10.1371/journal.pone.0212110 (DOI)000459709100037 ()30794577 (PubMedID)2-s2.0-85062005861 (Scopus ID)
Note

Originally included in thesis in manuscript form

Available from: 2017-05-15 Created: 2017-05-15 Last updated: 2019-11-19Bibliographically approved
Sandgren, K., Westerlinck, P., Jonsson, J. H., Blomqvist, L., Thellenberg Karlsson, C., Nyholm, T. & Dirix, P. (2019). Imaging for the Detection of Locoregional Recurrences in Biochemical Progression After Radical Prostatectomy: A Systematic Review. European Urology Focus, 5(4), 550-560
Open this publication in new window or tab >>Imaging for the Detection of Locoregional Recurrences in Biochemical Progression After Radical Prostatectomy: A Systematic Review
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2019 (English)In: European Urology Focus, ISSN 2405-4569, Vol. 5, no 4, p. 550-560Article, review/survey (Refereed) Published
Abstract [en]

Context: Local and regional recurrence after radical prostatectomy (RP) can be treated using salvage radiotherapy (SRT). If the recurrence can be delineated on diagnostic imaging, this could allow for increasingly individualized SRT.

Objective: This systematic review aimed at evaluating the evidence regarding the usefulness of positron emission tomography (PET) and magnetic resonance imaging (MRI) in identifying local and regional recurrences, with the aim to further individualize the SRT treatment.

Evidence acquisition: A systematic PubMed/Medline search was conducted in December 2015. Studies included were imaging studies of post-RP patients focusing on local and/or regional recurrence where sensitivity and specificity of MRI or PET were the primary end points. Only studies using biopsy, other histological analysis, and/or treatment follow-up as reference standard were included. Quality Assessment of Diagnostic Accuracy Studies-2 was used to score the study quality. Twenty-five articles were deemed of sufficient quality and included in the review.

Evidence synthesis: [11C]Acetate had the highest pooled sensitivity (92%), while [11C]choline and [18F]choline had pooled sensitivities of 71% and 84%, respectively. The PET tracer with highest pooled specificity was [11C]choline (86%). Regarding MRI, MR spectroscopy combined with dynamic contrast enhanced (DCE) MRI showed the highest pooled sensitivity (89%). High pooled sensitivities were also seen using multiparametric MRI (84%), diffusion-weighted MRI combined with T2-weigthed (T2w) imaging (82%), and DCE MRI combined with T2w imaging (82%). These also showed high pooled specificities (85%, 89%, and 92%, respectively).

Conclusions: Both MRI and PET have adequate sensitivity and specificity for the detection of prostate cancer recurrences post-RP. Multiparametric MRI, using diffusion-weighted and/or DCE imaging, and the choline-labeled tracers showed high pooled sensitivity and specificity, although their ranges were broad.

Patient summary: After reviewing imaging studies of recurrent prostate cancer after prostatectomy, we concluded that choline positron emission tomography and diffusion-weighted magnetic resonance imaging can be proposed as the current standard, with high sensitivity and specificity.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Magnetic resonance imaging, Positron emission tomography, Prostate cancer, Recurrence, Salvage radiotherapy
National Category
Urology and Nephrology Medical Image Processing
Identifiers
urn:nbn:se:umu:diva-142318 (URN)10.1016/j.euf.2017.11.001 (DOI)000486156800009 ()29133278 (PubMedID)2-s2.0-85033577338 (Scopus ID)
Available from: 2017-11-27 Created: 2017-11-27 Last updated: 2019-11-05Bibliographically approved
Daniel, M., Kuess, P., Andrzejewski, P., Nyholm, T., Helbich, T., Polanec, S., . . . Baltzer, P. (2019). Impact of androgen deprivation therapy on apparent diffusion coefficient and T2w MRI for histogram and texture analysis with respect to focal radiotherapy of prostate cancer. Strahlentherapie und Onkologie (Print), 195(5), 402-411
Open this publication in new window or tab >>Impact of androgen deprivation therapy on apparent diffusion coefficient and T2w MRI for histogram and texture analysis with respect to focal radiotherapy of prostate cancer
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2019 (English)In: Strahlentherapie und Onkologie (Print), ISSN 0179-7158, E-ISSN 1439-099X, Vol. 195, no 5, p. 402-411Article in journal (Refereed) Published
Abstract [en]

Purpose: Accurate prostate cancer (PCa) detection is essential for planning focal external beam radiotherapy (EBRT). While biparametric MRI (bpMRI) including T2-weighted (T2w) and diffusion-weighted images (DWI) is an accurate tool to localize PCa, its value is less clear in the case of additional androgen deprivation therapy (ADT). The aim of this study was to investigate the value of a textural feature (TF) approach on bpMRI analysis in prostate cancer patients with and without neoadjuvant ADT with respect to future dose-painting applications.

Methods: 28 PCa patients (54–80 years) with (n = 14) and without (n = 14) ADT who underwent bpMRI with T2w and DWI were analyzed retrospectively. Lesions, central gland (CG), and peripheral zone (PZ) were delineated by an experienced urogenital radiologist based on localized pre-therapeutic histopathology. Histogram parameters and 20 Haralick TF were calculated. Regional differences (i. e., tumor vs. PZ, tumor vs. CG) were analyzed for all imaging parameters. Receiver-operating characteristic (ROC) analysis was performed to measure diagnostic performance to distinguish PCa from benign prostate tissue and to identify the features with best discriminative power in both patient groups.

Results: The obtained sensitivities were equivalent or superior when utilizing the TF in the no-ADT group, while specificity was higher for the histogram parameters. However, in the ADT group, TF outperformed the conventional histogram parameters in both specificity and sensitivity. Rule-in and rule-out criteria for ADT patients could exclusively be defined with the aid of TF.

Conclusions: The TF approach has the potential for quantitative image-assisted boost volume delineation in PCa patients even if they are undergoing neoadjuvant ADT.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2019
Keywords
Radiomics, Tissue characterization, Boost volume, Quantitative imaging, ADC
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-159876 (URN)10.1007/s00066-018-1402-3 (DOI)000466399900005 ()30478670 (PubMedID)
Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-10Bibliographically approved
Wallstén, E., Axelsson, J., Jonsson, J. H., Thellenberg Karlsson, C., Nyholm, T. & Larsson, A. (2019). PET/MRI attenuation correction in the pelvic region with a statistical decomposition method. Paper presented at 32nd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), Barcelona, SPAIN, OCT 12-16, 2019. European Journal of Nuclear Medicine and Molecular Imaging, 46(SUPPL 1), S289-S290
Open this publication in new window or tab >>PET/MRI attenuation correction in the pelvic region with a statistical decomposition method
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2019 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 46, no SUPPL 1, p. S289-S290Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Aim/Introduction: Quantification in PET/MRI is of importance, and its accuracy is currently limited by the MR based attenuation correction estimate. A common method for attenuation correction of the pelvic region is based on a 2-echo Dixon MRI sequence for segmentation of fat and water and does not account for bone. In this work, we evaluate a new method for attenuation correction using an algorithm based on statistical decomposition of a T2 weighted MRI scan.

Materials and Methods: Substitute CT images (sCTs) were calculated from T2 weighted MRI scans with a statistical decomposition algorithm, originally developed for MRI-based radiotherapy dose-planning [1]. These sCTs benefits from having bone density information included, in addition to fat and water information. Prostate cancer patients from the PARAPLY study [2] were retrospectivelyselected, scanned with PET/MRI 11C-Acatate and CT the same day. The stand-alone CT images were transformed to the same geometry as the PET and MR images, using a non-rigid registration. CT images, generated sCT images, and the Dixonbased attenuation maps (MRAC), all in the same geometry, were together with the PET raw data used to reconstruct attenuation-corrected PET images using the PETrecon toolbox [GE Healthcare]. The two MR-based attenuation corrections were compared to the CT-based attenuation correction with root mean squared error (RMSE). Lesion analysis will also be reported. PET/MRI images were acquired on a Signa PET/MRI (GE Healthcare), and the CT images on a Brilliance Big Bore (Phillips Healthcare). The study will include 12 patients and a subset of 6 patients has been analyzed so far and is presented here.

Results: Soft tissue in-between pelvic bone structures were overestimated with 13% in MRAC-PET, and the error was reduced to 5% with sCT attenuation corrected PET (sCT-PET). For the whole patient volume, an average underestimation of 6% was found in the MRAC-PET, compared to 1% for sCTPET. RMSE within the body was reduced with a factor 2.5 with sCT-PET (RMSE=3.6%), compared to MRAC-PET (RMSE=8.8%).

Conclusion: Applying sCT from statistical decomposition as a base for calculation of attenuation maps reduces quantification errors in PET-images of the pelvic region compared to the common Dixon based method.

Place, publisher, year, edition, pages
Springer, 2019
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-165323 (URN)000492444402146 ()
Conference
32nd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), Barcelona, SPAIN, OCT 12-16, 2019
Available from: 2019-12-03 Created: 2019-12-03 Last updated: 2019-12-03Bibliographically approved
Daniel, M., Kuess, P., Andrzejewski, P., Nyholm, T., Nyholm, T., Heilmann, M., . . . Georg, D. (2019). Pilot study: Textural features of mpMRI for response assessment in prostate cancer patients. Paper presented at 38th Annual Meeting of the European-Society-for-Radiotherapy-and-Oncology (ESTRO), Milan, ITALY, April 26-30, 2019. Radiotherapy and Oncology, 133, S1113-S1113
Open this publication in new window or tab >>Pilot study: Textural features of mpMRI for response assessment in prostate cancer patients
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2019 (English)In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 133, p. S1113-S1113Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-160313 (URN)10.1016/S0167-8140(19)32448-X (DOI)000468315605227 ()
Conference
38th Annual Meeting of the European-Society-for-Radiotherapy-and-Oncology (ESTRO), Milan, ITALY, April 26-30, 2019
Available from: 2019-06-17 Created: 2019-06-17 Last updated: 2019-06-17Bibliographically approved
Sandgren, K., Johansson, L., Axelsson, J., Jonsson, J., Ögren, M., Ögren, M., . . . Widmark, A. (2019). Radiation dosimetry of [Ga-68]PSMA-11 in low-risk prostate cancer patients. EJNMMI Physics, 6, Article ID 2.
Open this publication in new window or tab >>Radiation dosimetry of [Ga-68]PSMA-11 in low-risk prostate cancer patients
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2019 (English)In: EJNMMI Physics, ISSN 2197-7364, E-ISSN 2191-219X, Vol. 6, article id 2Article in journal (Refereed) Published
Abstract [en]

Background: 68Ga-labeled Glu-NH-CO-NH-Lys(Ahx)-HBED-CC ([68Ga]PSMA-11) has been increasingly used to image prostate cancer using positron emission tomography (PET)/computed tomography (CT) both during diagnosis and treatment planning. It has been shown to be of clinical value for patients both in the primary and secondary stages of prostate cancer. The aim of this study was to determine the effective dose and organ doses from injection of [68Ga]PSMA-11 in a cohort of low-risk prostate cancer patients.

Methods: Six low-risk prostate cancer patients were injected with 133–178 MBq [68Ga]PSMA-11 and examined with four PET/CT acquisitions from injection to 255 min post-injection. Urine was collected up to 4 h post-injection, and venous blood samples were drawn at 45 min, 85 min, 175 min, and 245 min post-injection. Kidneys, liver, lungs, spleen, salivary and lacrimal glands, and total body where delineated, and cumulated activities and absorbed organ doses calculated. The software IDAC-Dose 2.1 was used to calculate absorbed organ doses according to the International Commission on Radiological Protection (ICRP) publication 107 using specific absorbed fractions published in ICRP 133 and effective dose according to ICRP Publication 103. We also estimated the absorbed dose to the eye lenses using Monte Carlo methods.

Results: [68Ga]PSMA-11 was rapidly cleared from the blood and accumulated preferentially in the kidneys and the liver. The substance has a biological half-life in blood of 6.5 min (91%) and 4.4 h (9%). The effective dose was calculated to 0.022 mSv/MBq. The kidneys received approximately 40 mGy after an injection with 160 MBq [68Ga]PSMA-11 while the lacrimal glands obtained an absorbed dose of 0.12 mGy per administered MBq. Regarding the eye lenses, the absorbed dose was low (0.0051 mGy/MBq).

Conclusion: The effective dose for [68Ga]PSMA-11 is 0.022 mSv/MBq, where the kidneys and lacrimal glands receiving the highest organ dose.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Radiation dosimetry, [Ga-68]PSMA-11, PSMA, PET-tracer, Prostate cancer, Absorbed dose and effective dose, Glu-NH-CO-NH-Lys(Ahx)-HBED-CC
National Category
Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-155760 (URN)10.1186/s40658-018-0239-2 (DOI)000455503100001 ()30631980 (PubMedID)
Available from: 2019-01-28 Created: 2019-01-28 Last updated: 2019-01-28Bibliographically approved
Fetty, L., Buschmann, M., Heilemann, G., Kuess, P., Nyholm, T., Herrmann, H., . . . Nesvacil, N. (2019). Solutions for MR-based RT planning with an open low field scanner using neural network tools. Paper presented at 38th Annual Meeting of the European-Society-for-Radiotherapy-and-Oncology (ESTRO), Milan, ITALY, April 26-30, 2019. Radiotherapy and Oncology, 133, S567-S568
Open this publication in new window or tab >>Solutions for MR-based RT planning with an open low field scanner using neural network tools
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2019 (English)In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 133, p. S567-S568Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-160315 (URN)10.1016/S0167-8140(19)31444-6 (DOI)000468315602288 ()
Conference
38th Annual Meeting of the European-Society-for-Radiotherapy-and-Oncology (ESTRO), Milan, ITALY, April 26-30, 2019
Available from: 2019-06-17 Created: 2019-06-17 Last updated: 2019-06-17Bibliographically approved
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