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Ilan, Ezgi
Publications (10 of 17) Show all publications
Jahn, U., Ilan, E., Sandström, M., Garske-Román, U., Velikyan, I., Fröss-Baron, K., . . . Sundin, A. (2018). 177Lu-DOTATATE Peptide Receptor Radionuclide Therapy; Gender Differences in Small Intestinal and Pancreatic Neuroendocrine Tumors. Paper presented at 31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY. European Journal of Nuclear Medicine and Molecular Imaging, 45, S61-S62
Open this publication in new window or tab >>177Lu-DOTATATE Peptide Receptor Radionuclide Therapy; Gender Differences in Small Intestinal and Pancreatic Neuroendocrine Tumors
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2018 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 45, p. S61-S62Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2018
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-372962 (URN)000449266200098 ()
Conference
31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-14Bibliographically approved
Ilan, E., Lubberink, M., Sandström, M., Jahn, U., Velikyan, I., Andersson, C., . . . Sundin, A. (2018). Comparison of Ga-68-DOTATATE and Lu-177-DOTATATE kinetics in neuroendocrine tumors. Paper presented at 31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY. European Journal of Nuclear Medicine and Molecular Imaging, 45, S276-S277
Open this publication in new window or tab >>Comparison of Ga-68-DOTATATE and Lu-177-DOTATATE kinetics in neuroendocrine tumors
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2018 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 45, p. S276-S277Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2018
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-372961 (URN)000449266202159 ()
Conference
31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-14Bibliographically approved
Lindström, E., Sundin, A., Trampal, C., Lindsjö, L., Ilan, E., Danfors, T., . . . Lubberink, M. (2018). Evaluation of penalized likelihood estimation reconstruction on a digital time-of-flight PET/CT scanner for 18F-FDG whole-body examinations. Journal of Nuclear Medicine, 59(7), 1152-1158
Open this publication in new window or tab >>Evaluation of penalized likelihood estimation reconstruction on a digital time-of-flight PET/CT scanner for 18F-FDG whole-body examinations
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2018 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 59, no 7, p. 1152-1158Article in journal (Refereed) Published
Abstract [en]

The resolution and quantitative accuracy of PET are highly influenced by the reconstruction method. Penalized-likelihood estimation algorithms allow for fully convergent iterative reconstruction, generating a higher image contrast than ordered-subsets expectation maximization (OSEM) while limiting noise. In this study, a type of penalized reconstruction known as block-sequential regularized expectation maximization (BSREM) was compared with time-of-flight OSEM (TOF OSEM). Various strengths of noise penalization factor β were tested along with various acquisition durations and transaxial fields of view (FOVs) with the aim of evaluating the performance and clinical use of BSREM for 18F-FDG PET/CT, both quantitatively and in a qualitative visual evaluation. Methods: Eleven clinical whole-body 18F-FDG PET/CT examinations acquired on a digital TOF PET/CT scanner were included. The data were reconstructed using BSREM with point-spread function recovery and β-factors of 133, 267, 400, and 533—and using TOF OSEM with point-spread function—for various acquisition times per bed position and various FOVs. Noise level, signal-to-noise ratio (SNR), signal-to-background ratio (SBR), and SUV were analyzed. A masked evaluation of visual image quality, rating several aspects, was performed by 2 nuclear medicine physicians to complement the analysis. Results: The lowest levels of noise were reached with the highest β-factor, resulting in the highest SNR, which in turn resulted in the lowest SBR. A β-factor of 400 gave noise equivalent to TOF OSEM but produced a significant increase in SUVmax (11%), SNR (22%), and SBR (12%). BSREM with a β-factor of 533 at a decreased acquisition duration (2 min/bed position) was comparable to TOF OSEM at a full acquisition duration (3 min/bed position). Reconstructed FOV had an impact on BSREM outcome measures; SNR increased and SBR decreased when FOV was shifted from 70 to 50 cm. The evaluation of visual image quality resulted in similar scores for reconstructions, although a β-factor of 400 obtained the highest mean whereas a β-factor of 267 was ranked best in overall image quality, contrast, sharpness, and tumor detectability. Conclusion: In comparison with TOF OSEM, penalized BSREM reconstruction resulted in an increased tumor SUVmax and an improved SNR and SBR at a matched level of noise. BSREM allowed for a shorter acquisition than TOF OSEM, with equal image quality.

Keywords
FDG, Image Reconstruction, Molecular Imaging, PET/CT, block-sequential regularized expectation maximization, image reconstruction, penalization factor
National Category
Medical and Health Sciences Medical Image Processing
Identifiers
urn:nbn:se:uu:diva-343272 (URN)10.2967/jnumed.117.200790 (DOI)000437237200037 ()29449445 (PubMedID)
Available from: 2018-02-26 Created: 2018-02-26 Last updated: 2018-09-18Bibliographically approved
Wilking, H., Ilan, E., Sandström, M., Andersson, C., Öst, A., Velikyan, I., . . . Lubberink, M. (2018). In-vivo stability of 177Lu-DOTATATE during peptide receptor radionuclide therapy. Paper presented at 31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY.. European Journal of Nuclear Medicine and Molecular Imaging, 45(Supplement 1), S592-S592
Open this publication in new window or tab >>In-vivo stability of 177Lu-DOTATATE during peptide receptor radionuclide therapy
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2018 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 45, no Supplement 1, p. S592-S592Article in journal, Meeting abstract (Other academic) Published
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-373341 (URN)10.1007/s00259-018-4148-3 (DOI)000449266205174 ()
Conference
31st Annual Congress of the European-Association-of-Nuclear-Medicine (EANM), OCT 13-17, 2018, Dusseldorf, GERMANY.
Note

Meeting Abstract: EP-0729

Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2019-01-15Bibliographically approved
Sandström, M., Ilan, E., Fröss-Baron, K., Garske, U., Granberg, D., Eriksson, B., . . . Lubberink, M. (2017). Gender-related differences in absorbed dose to risk organs in patients receiving Lu-177-Octreotate therapy. European Journal of Nuclear Medicine and Molecular Imaging, 44, S158-S158
Open this publication in new window or tab >>Gender-related differences in absorbed dose to risk organs in patients receiving Lu-177-Octreotate therapy
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2017 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 44, p. S158-S158Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2017
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-377088 (URN)000455019400056 ()
Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-02-19Bibliographically approved
Sandström, M., Ilan, E., Sundin, A. & Lubberink, M. (2017). Image quality measurements with 177Lu on a GE Discovery 670 CZT. Paper presented at Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), JUN 10-14, 2017, Denver, CO. Journal of Nuclear Medicine, 58(S1), Article ID 763.
Open this publication in new window or tab >>Image quality measurements with 177Lu on a GE Discovery 670 CZT
2017 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 58, no S1, article id 763Article in journal, Meeting abstract (Other academic) Published
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-333340 (URN)000404949903161 ()
Conference
Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), JUN 10-14, 2017, Denver, CO
Note

Title in WoS: Image quality measurements with Lu-177 on a GE Discovery 670 CZT

Available from: 2017-11-14 Created: 2017-11-14 Last updated: 2017-11-14Bibliographically approved
Sandström, M., Ilan, E., Sundin, A. & Lubberink, M. (2017). Is there a gender difference of absorbed dose to the risk organs in patients receiving 177Lu-Octreotate therapy?. Paper presented at Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), JUN 10-14, 2017, Denver, CO. Journal of Nuclear Medicine, 58(S1), Article ID 248.
Open this publication in new window or tab >>Is there a gender difference of absorbed dose to the risk organs in patients receiving 177Lu-Octreotate therapy?
2017 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 58, no S1, article id 248Article in journal, Meeting abstract (Other academic) Published
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-333341 (URN)000404949901056 ()
Conference
Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), JUN 10-14, 2017, Denver, CO
Note

Title in WoS: Is there a gender difference of absorbed dose to the risk organs in patients receiving Lu-177-Octreotate therapy?

Available from: 2017-11-14 Created: 2017-11-14 Last updated: 2017-11-14Bibliographically approved
Ilan, E., Sundin, A., Velikyan, I., Sandström, M. & Lubberink, M. (2017). Low tracer availability of Ga-68-DOTATOC and Ga-68-DOTATATE in blood for patients with high SSTR density leads to non-linear correlation between SUV and K-i. European Journal of Nuclear Medicine and Molecular Imaging, 44, S279-S279
Open this publication in new window or tab >>Low tracer availability of Ga-68-DOTATOC and Ga-68-DOTATATE in blood for patients with high SSTR density leads to non-linear correlation between SUV and K-i
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2017 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 44, p. S279-S279Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2017
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-377075 (URN)000455019400307 ()
Available from: 2019-02-21 Created: 2019-02-21 Last updated: 2019-02-21Bibliographically approved
Lindström, E., Lindsjö, L., Ilan, E., Sundin, A., Sörensen, J., Danfors, T., . . . Lubberink, M. (2017). Optimisation of penalized likelihood estimation reconstruction (Q.Clear) on a digital time-of-flight PET-CT scanner for four different PET tracers. Paper presented at Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), JUN 10-14, 2017, Denver, CO. Journal of Nuclear Medicine, 58(S1), Article ID 1355.
Open this publication in new window or tab >>Optimisation of penalized likelihood estimation reconstruction (Q.Clear) on a digital time-of-flight PET-CT scanner for four different PET tracers
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2017 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 58, no S1, article id 1355Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Objectives: The penalized likelihood estimation reconstruction algorithm Q.Clear (GE Healthcare) allows for full convergence and edge preservation through a block sequential regularized expectation maximization technique. In this study the performance of Q.Clear was investigated for different penalization factors (β) with the aim to optimize its clinical use for four different tracers.

Methods: Q.Clear reconstructions with β values of 200, 400, 600 and 800 were compared to time-of-flight ordered subset expectation maximization (TF-OSEM) (3 iterations, 16 subsets and 5 mm Gaussian filter) with point spread function recovery. Clinical whole-body PET/CT (Discovery MI, GE Healthcare) scans with 68Ga-DOTATOC, 18F-FDG, 11C-acetate or 18F-fluoride were analyzed for level of noise in healthy liver tissue, signal to noise ratio (SNR), signal to background ratio (SBR) and maximum standardized uptake value (SUVmax). In addition, acquisition times per bed position and transaxial field of view (FOV) of the reconstructed images were varied. For each tracer, images from 10 patients were included, with a mean of 30 lesions per tracer. A spherical reference volume of interest (VOI) was placed in the liver and lesions were delineated employing a 41% threshold of the maximum voxel.

Results: The lowest levels of noise were reached with the highest beta factor resulting in the highest SNR, but this in turn gave the lowest SBR. Noise equivalence to OSEM was found with β 600 for 68Ga-DOTATOC, 18F-FDG and 18F-fluoride, and β 400 for 11C-acetate with a resulting significant increase of SUVmax (19.4%, 9.7%, 22.5% and 19.0% respectively) (P < 0.0001, paired t-test), SNR (22.1%, 22.6%, 9.5% and 33.6%) and SBR (19.5%, 11.7%, 21.3% and 18.5%) compared to OSEM. SNR decreased while SBR increased for all tracers when extending FOV from 500 to 700 mm, but only significantly for 18F-fluoride. Decreasing image acquisition time gave no statistical difference of SUVmax for 68Ga-DOTATOC, 18F-fluoride (2 to 1.5 min) for any reconstruction method nor for 11C-acetate (3 to 2 min) with β 蠅 400. Decreasing time for 18F-FDG (3 to 2 min) resulted in a change of optimal beta to β 800 in order to reach noise equivalence to OSEM along with maintaining a higher SNR than OSEM.

Conclusion: Images reconstructed by Q.Clear result in a tracer-dependent increase in tumour SUVmax values compared to OSEM at matched levels of noise, and an improved SNR. The optimal penalization factor, both in terms of noise-equivalence to OSEM and in terms of absolute SNR, is tracer dependent.

National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-333337 (URN)000404949906146 ()
Conference
Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), JUN 10-14, 2017, Denver, CO
Available from: 2017-11-15 Created: 2017-11-15 Last updated: 2017-11-15Bibliographically approved
Ilan, E., Sandström, M., Velikyan, I., Sundin, A., Eriksson, B. & Lubberink, M. (2017). Parametric Net Influx Rate Images of 68Ga-DOTATOC and 68Ga-DOTATATE: Quantitative Accuracy and Improved Image Contrast. Journal of Nuclear Medicine, 58(5), 744-749
Open this publication in new window or tab >>Parametric Net Influx Rate Images of 68Ga-DOTATOC and 68Ga-DOTATATE: Quantitative Accuracy and Improved Image Contrast
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2017 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 58, no 5, p. 744-749Article in journal (Refereed) Published
Abstract [en]

(68)Ga-DOTATOC and (68)Ga-DOTATATE are radiolabelled somatostatin analogs used for diagnosis of somatostatin receptor expressing neuroendocrine tumors (NETs) and SUV -measurements are suggested for treatment monitoring. However, changes in net-influx rate (Ki) may better reflect treatment effects than those of the SUV, and accordingly there is a need to compute parametric images showing Ki at the voxel level. The aim of this study was to evaluate parametric methods for computation of parametric Ki images by comparison to volume of interest based methods and to assess image contrast in terms of tumor-to-liver ratio.

METHODS: Ten patients with metastatic NETs underwent a 45-min dynamic PET examination followed by whole-body PET/CT at 1 h post injection of (68)Ga-DOTATOC and (68)Ga-DOTATATE on consecutive days. Parametric Ki images were computed using a basis function method (BFM) implementation of the two tissue irreversible compartment model and the Patlak method using a descending aorta image-derived input function, and mean tumor Ki values were determined for 50% isocontour VOIs and compared to Ki values based on non-linear regression (NLR) of the whole-VOI time-activity curve. A subsample of healthy liver was delineated in the whole-body and Ki images and tumor-to-liver ratios were calculated in order to evaluate image contrast. Correlation and agreement between VOI-based and parametric Ki values were assessed using regression and Bland-Altman analysis.

RESULTS: Correlation (R2) between NLR-based and parametric image-based (BFM) tumor Ki values was 0.98 (slope 0.81) and 0.97 (slope 0.88) for (68)Ga-DOTATOC and (68)Ga DOTATATE, respectively. For Patlak analysis, correlation between NLR-based and parametric based (Patlak) tumor Ki were 0.95 (slope 0.71) and 0.92 (slope 0.74) for (68)Ga-DOTATOC and (68)Ga-DOTATATE, respectively. There was no bias between NLR and parametric based Ki-values. Tumor-to-liver contrast was 1.6 and 2.0 times higher in the parametric BFM-Ki images, and 2.3 and 3.0 times in the Patlak images, than in the whole-body images for (68)Ga-DOTATOC and (68)Ga-DOTATATE, respectively.

CONCLUSION: A high correlation and agreement between NLR- and parametric based Ki values was found, showing that parametric net influx rate images are quantitatively accurate. In addition, tumor-to-liver contrast was superior in the parametric Ki images compared to whole-body images both for (68)Ga-DOTATOC and (68)Ga DOTATATE.

National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-308417 (URN)10.2967/jnumed.116.180380 (DOI)000400633500015 ()27789716 (PubMedID)
Available from: 2016-11-25 Created: 2016-11-25 Last updated: 2018-09-03Bibliographically approved
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