Pub Date : 2023-09-01DOI: 10.1016/j.zemedi.2023.08.005
Agilo Luitger Kern, Marcel Gutberlet, Regina Rumpel, Inga Bruesch, Jens M Hohlfeld, Frank Wacker, Bennet Hensen
129Xe hyperpolarized gas chemical exchange saturation transfer (HyperCEST) MRI has been suggested as molecular imaging modality but translation to in vivo imaging has been slow, likely due to difficulties of synthesizing suitable molecules. Cucurbit[6]uril-either in readily available non-functionalized or potentially in functionalized form-may, combined with 129Xe HyperCEST MRI, prove useful as a switchable 129Xe MR contrast agent but the likely differential properties of contrast generation in individual chemical compartments as well as the influence of 129Xe signal drifts encountered in vivo on HyperCEST MRI are unknown. Here, HyperCEST z spectroscopy and chemical shift imaging with compartment-specific analysis are performed in a total of 10 rats using cucurbit[6]uril injected i.v. and under a protocol employing spontaneous respiration. Differences in intensity of the HyperCEST effect between chemical compartments and anatomical regions are investigated. Strategies to mitigate influence of signal instabilities associated with drifts in physiological parameters are developed. It is shown that presence of cucurbit[6]uril can be readily detected under spontaneous 129Xe inhalation mostly in aqueous tissues further away from the lung. Differences of effect intensity in individual regions and compartments must be considered in HyperCEST data interpretation. In particular, there seems to be almost no effect in lipids. 129Xe HyperCEST MR measurements utilizing spontaneous respiration protocols and extended measurement times are feasible. HyperCEST MRI of non-functionalized cucurbit[6]uril may create contrast between anatomical structures in vivo.
{"title":"Compartment-specific <sup>129</sup>Xe HyperCEST z spectroscopy and chemical shift imaging of cucurbit[6]uril in spontaneously breathing rats.","authors":"Agilo Luitger Kern, Marcel Gutberlet, Regina Rumpel, Inga Bruesch, Jens M Hohlfeld, Frank Wacker, Bennet Hensen","doi":"10.1016/j.zemedi.2023.08.005","DOIUrl":"https://doi.org/10.1016/j.zemedi.2023.08.005","url":null,"abstract":"<p><p><sup>129</sup>Xe hyperpolarized gas chemical exchange saturation transfer (HyperCEST) MRI has been suggested as molecular imaging modality but translation to in vivo imaging has been slow, likely due to difficulties of synthesizing suitable molecules. Cucurbit[6]uril-either in readily available non-functionalized or potentially in functionalized form-may, combined with <sup>129</sup>Xe HyperCEST MRI, prove useful as a switchable <sup>129</sup>Xe MR contrast agent but the likely differential properties of contrast generation in individual chemical compartments as well as the influence of <sup>129</sup>Xe signal drifts encountered in vivo on HyperCEST MRI are unknown. Here, HyperCEST z spectroscopy and chemical shift imaging with compartment-specific analysis are performed in a total of 10 rats using cucurbit[6]uril injected i.v. and under a protocol employing spontaneous respiration. Differences in intensity of the HyperCEST effect between chemical compartments and anatomical regions are investigated. Strategies to mitigate influence of signal instabilities associated with drifts in physiological parameters are developed. It is shown that presence of cucurbit[6]uril can be readily detected under spontaneous <sup>129</sup>Xe inhalation mostly in aqueous tissues further away from the lung. Differences of effect intensity in individual regions and compartments must be considered in HyperCEST data interpretation. In particular, there seems to be almost no effect in lipids. <sup>129</sup>Xe HyperCEST MR measurements utilizing spontaneous respiration protocols and extended measurement times are feasible. HyperCEST MRI of non-functionalized cucurbit[6]uril may create contrast between anatomical structures in vivo.</p>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10136802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-18DOI: 10.1016/j.zemedi.2023.07.007
Maikol Salas-Ramirez, Lydia Maigne, Giovanna Fois, Harry Scherthan, Michael Lassmann, Uta Eberlein
<p><p>This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal ex vivo irradiation of whole blood with the radionuclides <sup>90</sup>Y, <sup>99m</sup>Tc, <sup>123</sup>I, <sup>131</sup>I, <sup>177</sup>Lu, <sup>223</sup>Ra, and <sup>225</sup>Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level.</p><p><strong>Methods: </strong>The simulation at the macroscopic level reproduces an 8 mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal ex vivo blood irradiation. The lymphocytes were simulated as spheres of 3.75 µm radius randomly distributed, with a concentration of 125 spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the clustering example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1 µm radius. The absorbed dose coefficients for lymphocyte nuclei (d<sub>Lymph</sub>) were calculated and compared with macroscopic whole blood absorbed dose coefficients (d<sub>Blood</sub>). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIF∙cell<sup>-1</sup>∙mGy<sup>-1</sup>) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, d<sub>Lymph</sub> and the number of α-tracks∙100 cell<sup>-1</sup>∙mGy<sup>-1</sup> and DBSs∙µm<sup>-1</sup> were calculated using experiment-based thresholds for the α-track lengths and DBSs/track values. The results were compared with the results of an ex vivo study with <sup>223</sup>Ra.</p><p><strong>Results: </strong>The d<sub>Lymph</sub> values differed from the d<sub>Blood</sub> values by -1.0% (<sup>90</sup>Y), -5.2% (<sup>99m</sup>Tc), -22.3% (<sup>123</sup>I), 0.35% (<sup>131</sup>I), 2.4% (<sup>177</sup>Lu), -5.6% (<sup>223</sup>Ra) and -6.1% (<sup>225</sup>Ac). The number of DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> for each radionuclide was 0.015 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>90</sup>Y), 0.012 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>99m</sup>Tc), 0.014DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>123</sup>I), 0.012 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>131</sup>I), and 0.016 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>177</sup>Lu). These values agree very well with experimental data. The number of α-tracks∙100 cells<sup>-1</sup>∙mGy<sup>-1</sup> for <sup>223</sup>Ra and <sup>225</sup>Ac w
{"title":"Radiation-induced double-strand breaks by internal ex vivo irradiation of lymphocytes: Validation of a Monte Carlo simulation model using GATE and Geant4-DNA.","authors":"Maikol Salas-Ramirez, Lydia Maigne, Giovanna Fois, Harry Scherthan, Michael Lassmann, Uta Eberlein","doi":"10.1016/j.zemedi.2023.07.007","DOIUrl":"https://doi.org/10.1016/j.zemedi.2023.07.007","url":null,"abstract":"<p><p>This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal ex vivo irradiation of whole blood with the radionuclides <sup>90</sup>Y, <sup>99m</sup>Tc, <sup>123</sup>I, <sup>131</sup>I, <sup>177</sup>Lu, <sup>223</sup>Ra, and <sup>225</sup>Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level.</p><p><strong>Methods: </strong>The simulation at the macroscopic level reproduces an 8 mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal ex vivo blood irradiation. The lymphocytes were simulated as spheres of 3.75 µm radius randomly distributed, with a concentration of 125 spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the clustering example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1 µm radius. The absorbed dose coefficients for lymphocyte nuclei (d<sub>Lymph</sub>) were calculated and compared with macroscopic whole blood absorbed dose coefficients (d<sub>Blood</sub>). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIF∙cell<sup>-1</sup>∙mGy<sup>-1</sup>) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, d<sub>Lymph</sub> and the number of α-tracks∙100 cell<sup>-1</sup>∙mGy<sup>-1</sup> and DBSs∙µm<sup>-1</sup> were calculated using experiment-based thresholds for the α-track lengths and DBSs/track values. The results were compared with the results of an ex vivo study with <sup>223</sup>Ra.</p><p><strong>Results: </strong>The d<sub>Lymph</sub> values differed from the d<sub>Blood</sub> values by -1.0% (<sup>90</sup>Y), -5.2% (<sup>99m</sup>Tc), -22.3% (<sup>123</sup>I), 0.35% (<sup>131</sup>I), 2.4% (<sup>177</sup>Lu), -5.6% (<sup>223</sup>Ra) and -6.1% (<sup>225</sup>Ac). The number of DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> for each radionuclide was 0.015 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>90</sup>Y), 0.012 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>99m</sup>Tc), 0.014DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>123</sup>I), 0.012 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>131</sup>I), and 0.016 DSB∙cell<sup>-1</sup>∙mGy<sup>-1</sup> (<sup>177</sup>Lu). These values agree very well with experimental data. The number of α-tracks∙100 cells<sup>-1</sup>∙mGy<sup>-1</sup> for <sup>223</sup>Ra and <sup>225</sup>Ac w","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10088978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-14DOI: 10.1016/j.zemedi.2023.07.006
Kajal Kumari, Mayank Goswami
Three types of gamma radiation detectors associated with distributed electronics namely, NaI (Tl), HPGe and LaBr3(Ce) are compared primarily focusing on electronic noise and scattering noise. Additionally, detectors of same make, material, size and electronics are also compared. A methodology is proposed to select the most suitable detector for computed tomography (CT) among the available options. Standard deviation parameter is employed to estimate electronic noise without performing CT experiment. Kanpur theorem-1(KT-1) is used to estimate the scattering noise quantitatively after verifying its sensitivity to scattering noise. The impact of scattering noise on CT profiles is evaluated using dice similarity dice coefficient. A good resemblance between KT-1 and dice coefficient is observed. A maximum difference of 56% in scattering noise is observed when five detectors used simultaneously instead of single detector whereas a discrepancy of 85% is observed between different types of radiation detectors. As far as ease of handling, operational and capital cost is concern one has to compromise minimum 12% of accuracy in CT reconstruction if NaI (Tl) detector is used with respect to best alternative available. The proposed methodology can be applied to measurement that require minimal scattering interference data other than CT experiments. The manufacturer can add noise level of detector as a characteristic parameter in the data sheet.
{"title":"Gamma radiation detector selection for CT scanner.","authors":"Kajal Kumari, Mayank Goswami","doi":"10.1016/j.zemedi.2023.07.006","DOIUrl":"https://doi.org/10.1016/j.zemedi.2023.07.006","url":null,"abstract":"<p><p>Three types of gamma radiation detectors associated with distributed electronics namely, NaI (Tl), HPGe and LaBr<sub>3</sub>(Ce) are compared primarily focusing on electronic noise and scattering noise. Additionally, detectors of same make, material, size and electronics are also compared. A methodology is proposed to select the most suitable detector for computed tomography (CT) among the available options. Standard deviation parameter is employed to estimate electronic noise without performing CT experiment. Kanpur theorem-1(KT-1) is used to estimate the scattering noise quantitatively after verifying its sensitivity to scattering noise. The impact of scattering noise on CT profiles is evaluated using dice similarity dice coefficient. A good resemblance between KT-1 and dice coefficient is observed. A maximum difference of 56% in scattering noise is observed when five detectors used simultaneously instead of single detector whereas a discrepancy of 85% is observed between different types of radiation detectors. As far as ease of handling, operational and capital cost is concern one has to compromise minimum 12% of accuracy in CT reconstruction if NaI (Tl) detector is used with respect to best alternative available. The proposed methodology can be applied to measurement that require minimal scattering interference data other than CT experiments. The manufacturer can add noise level of detector as a characteristic parameter in the data sheet.</p>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10016697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-07DOI: 10.1016/j.zemedi.2023.07.003
Ivan I Maximov, Lars T Westlye
The standard diffusion MRI model with intra- and extra-axonal water pools offers a set of microstructural parameters describing brain white matter architecture. However, non-linearities in the standard model and diffusion data contamination by noise and imaging artefacts make estimation of diffusion metrics challenging. In order to develop reliable diffusion approaches and to avoid computational model degeneracy, additional theoretical assumptions allowing stable numerical implementations are required. Advanced diffusion approaches allow for estimation of intra-axonal water fraction (AWF), describing a key structural characteristic of brain tissue. AWF can be interpreted as an indirect measure or proxy of neurite density and has a potential as useful clinical biomarker. Established diffusion approaches such as white matter tract integrity, neurite orientation dispersion and density imaging (NODDI), and spherical mean technique provide estimates of AWF within their respective theoretical frameworks. In the present study, we estimated AWF metrics using different diffusion approaches and compared measures of brain asymmetry between the different metrics in a sub-sample of 182 subjects from the UK Biobank. Multivariate decomposition by mean of linked independent component analysis revealed that the various AWF proxies derived from the different diffusion approaches reflect partly non-overlapping variance of independent components, with distinct anatomical distributions and sensitivity to age. Further, voxel-wise analysis revealed age-related differences in AWF-based brain asymmetry, indicating less apparent left-right hemisphere difference with higher age. Finally, we demonstrated that NODDI metrics suffer from a quite strong dependence on used numerical algorithms and post-processing pipeline. The analysis based on AWF metrics strongly depends on the used diffusion approach and leads to poorly reproducible results.
{"title":"Comparison of different neurite density metrics with brain asymmetry evaluation.","authors":"Ivan I Maximov, Lars T Westlye","doi":"10.1016/j.zemedi.2023.07.003","DOIUrl":"https://doi.org/10.1016/j.zemedi.2023.07.003","url":null,"abstract":"<p><p>The standard diffusion MRI model with intra- and extra-axonal water pools offers a set of microstructural parameters describing brain white matter architecture. However, non-linearities in the standard model and diffusion data contamination by noise and imaging artefacts make estimation of diffusion metrics challenging. In order to develop reliable diffusion approaches and to avoid computational model degeneracy, additional theoretical assumptions allowing stable numerical implementations are required. Advanced diffusion approaches allow for estimation of intra-axonal water fraction (AWF), describing a key structural characteristic of brain tissue. AWF can be interpreted as an indirect measure or proxy of neurite density and has a potential as useful clinical biomarker. Established diffusion approaches such as white matter tract integrity, neurite orientation dispersion and density imaging (NODDI), and spherical mean technique provide estimates of AWF within their respective theoretical frameworks. In the present study, we estimated AWF metrics using different diffusion approaches and compared measures of brain asymmetry between the different metrics in a sub-sample of 182 subjects from the UK Biobank. Multivariate decomposition by mean of linked independent component analysis revealed that the various AWF proxies derived from the different diffusion approaches reflect partly non-overlapping variance of independent components, with distinct anatomical distributions and sensitivity to age. Further, voxel-wise analysis revealed age-related differences in AWF-based brain asymmetry, indicating less apparent left-right hemisphere difference with higher age. Finally, we demonstrated that NODDI metrics suffer from a quite strong dependence on used numerical algorithms and post-processing pipeline. The analysis based on AWF metrics strongly depends on the used diffusion approach and leads to poorly reproducible results.</p>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9974632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-07DOI: 10.1016/j.zemedi.2023.07.004
Hao Song, Johannes Fisher, Ali Caglar Özen, Burak Akin, Stefan Schumann, Michael Bock
Objective: To investigate the feasibility of cerebral metabolic rate of oxygen consumption (CMRO2) measurements with MRI at 3 Tesla in different brain regions.
Methods: CMRO2 represents a key indicator of the physiological state of brain tissue. Dynamic 17O-MRI with inhalation of isotopically enriched 17O gas has been used to quantify global CMRO2 in brain white (WM) and gray matter (GM). However, global CMRO2 can only reflect the overall oxygen metabolism of the brain and cannot provide enough information on local tissue oxygen metabolism. To investigate the feasibility of determination of regional CMRO2 at a clinical 3 T MRI system, CMRO2 values in frontal, parietal and occipital WM and GM were determined in 5 healthy volunteers and compared to evaluate the regional differences of oxygen metabolism in WM and GM. Additionally, regional CMRO2 values were determined in deep brain structures including thalamus, dorsal striatum, caudate nucleus and insula cortex and in the cerebella, and compared with literature values from 15O-PET studies.
Results: In cortical GM the determined CMRO2 values were in good agreement with the literature, whereas values in WM were about 32-48% higher than literature values. Regional analysis revealed a significantly higher CMRO2 in the occipital GM compared to the frontal and parietal GM. By contrast, no significant difference of CMRO2 was observed across the WM. In addition, CMRO2 in deep brain structures was lower compared to literature values and in the cerebella a good hemispheric symmetry of the tissue oxygen metabolism was found.
Conclusion: Dynamic 17O-MRI enables direct, non-invasive determination of regional CMRO2 in brain structures in healthy volunteers at 3T.
{"title":"Quantification of regional CMRO<sub>2</sub> in human brain using dynamic <sup>17</sup>O-MRI at 3T.","authors":"Hao Song, Johannes Fisher, Ali Caglar Özen, Burak Akin, Stefan Schumann, Michael Bock","doi":"10.1016/j.zemedi.2023.07.004","DOIUrl":"https://doi.org/10.1016/j.zemedi.2023.07.004","url":null,"abstract":"<p><strong>Objective: </strong>To investigate the feasibility of cerebral metabolic rate of oxygen consumption (CMRO<sub>2</sub>) measurements with MRI at 3 Tesla in different brain regions.</p><p><strong>Methods: </strong>CMRO<sub>2</sub> represents a key indicator of the physiological state of brain tissue. Dynamic <sup>17</sup>O-MRI with inhalation of isotopically enriched <sup>17</sup>O gas has been used to quantify global CMRO<sub>2</sub> in brain white (WM) and gray matter (GM). However, global CMRO<sub>2</sub> can only reflect the overall oxygen metabolism of the brain and cannot provide enough information on local tissue oxygen metabolism. To investigate the feasibility of determination of regional CMRO<sub>2</sub> at a clinical 3 T MRI system, CMRO<sub>2</sub> values in frontal, parietal and occipital WM and GM were determined in 5 healthy volunteers and compared to evaluate the regional differences of oxygen metabolism in WM and GM. Additionally, regional CMRO<sub>2</sub> values were determined in deep brain structures including thalamus, dorsal striatum, caudate nucleus and insula cortex and in the cerebella, and compared with literature values from <sup>15</sup>O-PET studies.</p><p><strong>Results: </strong>In cortical GM the determined CMRO<sub>2</sub> values were in good agreement with the literature, whereas values in WM were about 32-48% higher than literature values. Regional analysis revealed a significantly higher CMRO<sub>2</sub> in the occipital GM compared to the frontal and parietal GM. By contrast, no significant difference of CMRO<sub>2</sub> was observed across the WM. In addition, CMRO<sub>2</sub> in deep brain structures was lower compared to literature values and in the cerebella a good hemispheric symmetry of the tissue oxygen metabolism was found.</p><p><strong>Conclusion: </strong>Dynamic <sup>17</sup>O-MRI enables direct, non-invasive determination of regional CMRO<sub>2</sub> in brain structures in healthy volunteers at 3T.</p>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10320518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-01DOI: 10.1016/j.zemedi.2023.04.009
Linyu Ni , Xueding Wang , Guan Xu
Photoacoustic (PA) imaging has been extensively investigated in application in biomedicine over the last decade. This article reviews the motivation, significance, and system configuration of a few ongoing studies of implementing photoacoustic technology in musculoskeletal imaging, abdominal imaging, and interstitial sensing. The review then summarizes the methodologies and latest progress of relevant projects. Finally, we discuss our expectations for the future of translation research in PA imaging.
{"title":"Photoacoustic clinical applications: Musculoskeletal and abdominal imaging","authors":"Linyu Ni , Xueding Wang , Guan Xu","doi":"10.1016/j.zemedi.2023.04.009","DOIUrl":"10.1016/j.zemedi.2023.04.009","url":null,"abstract":"<div><p>Photoacoustic (PA) imaging has been extensively investigated in application in biomedicine over the last decade. This article reviews the motivation, significance, and system configuration of a few ongoing studies of implementing photoacoustic technology in musculoskeletal imaging, abdominal imaging, and interstitial sensing. The review then summarizes the methodologies and latest progress of relevant projects. Finally, we discuss our expectations for the future of translation research in PA imaging.</p></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"33 3","pages":"Pages 324-335"},"PeriodicalIF":2.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/b4/ab/main.PMC10517401.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10664459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-01DOI: 10.1016/j.zemedi.2023.01.004
Mitra Aliabouzar , Oliver D. Kripfgans , J. Brian Fowlkes , Mario L. Fabiilli
The development of phase-shift droplets has broadened the scope of ultrasound-based biomedical applications. When subjected to sufficient acoustic pressures, the perfluorocarbon phase in phase-shift droplets undergoes a phase-transition to a gaseous state. This phenomenon, termed acoustic droplet vaporization (ADV), has been the subject of substantial research over the last two decades with great progress made in design of phase-shift droplets, fundamental physics of bubble nucleation and dynamics, and applications. Here, we review experimental approaches, carried out via high-speed microscopy, as well as theoretical models that have been proposed to study the fundamental physics of ADV including vapor nucleation and ADV-induced bubble dynamics. In addition, we highlight new developments of ADV in tissue regeneration, which is a relatively recently exploited application. We conclude this review with future opportunities of ADV for advanced applications such as in situ microrheology and pressure estimation.
{"title":"Bubble nucleation and dynamics in acoustic droplet vaporization: a review of concepts, applications, and new directions","authors":"Mitra Aliabouzar , Oliver D. Kripfgans , J. Brian Fowlkes , Mario L. Fabiilli","doi":"10.1016/j.zemedi.2023.01.004","DOIUrl":"10.1016/j.zemedi.2023.01.004","url":null,"abstract":"<div><p>The development of phase-shift droplets has broadened the scope of ultrasound-based biomedical applications. When subjected to sufficient acoustic pressures, the perfluorocarbon phase in phase-shift droplets undergoes a phase-transition to a gaseous state. This phenomenon, termed acoustic droplet vaporization (ADV), has been the subject of substantial research over the last two decades with great progress made in design of phase-shift droplets, fundamental physics of bubble nucleation and dynamics, and applications. Here, we review experimental approaches, carried out via high-speed microscopy, as well as theoretical models that have been proposed to study the fundamental physics of ADV including vapor nucleation and ADV-induced bubble dynamics. In addition, we highlight new developments of ADV in tissue regeneration, which is a relatively recently exploited application. We conclude this review with future opportunities of ADV for advanced applications such as <em>in situ</em> microrheology and pressure estimation.</p></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"33 3","pages":"Pages 387-406"},"PeriodicalIF":2.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/ac/28/main.PMC10517405.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10281562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-01DOI: 10.1016/j.zemedi.2023.04.001
Pengfei Song , Jonathan M. Rubin , Matthew R. Lowerison
The field of super-resolution ultrasound microvascular imaging has been rapidly growing over the past decade. By leveraging contrast microbubbles as point targets for localization and tracking, super-resolution ultrasound pinpoints the location of microvessels and measures their blood flow velocity. Super-resolution ultrasound is the first in vivo imaging modality that can image micron-scale vessels at a clinically relevant imaging depth without tissue destruction. These unique capabilities of super-resolution ultrasound provide structural (vessel morphology) and functional (vessel blood flow) assessments of tissue microvasculature on a global and local scale, which opens new doors for many enticing preclinical and clinical applications that benefit from microvascular biomarkers. The goal of this short review is to provide an update on recent advancements in super-resolution ultrasound imaging, with a focus on summarizing existing applications and discussing the prospects of translating super-resolution imaging to clinical practice and research. In this review, we also provide brief introductions of how super-resolution ultrasound works, how does it compare with other imaging modalities, and what are the tradeoffs and limitations for an audience who is not familiar with the technology.
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Pub Date : 2023-08-01DOI: 10.1016/j.zemedi.2023.04.006
James Wiskin , Bilal Malik , John Klock
<div><p>A novel 3D ultrasound tomographic (3D UT) method (called volography) that creates a speed of sound (SOS) map and a reflection modality that is co-registered are reviewed and shown to be artifact free even in the presence of high contrast and thus shown to be applicable for breast, orthopedic and pediatric clinical use cases. The 3D UT images are almost isotropic with mm resolution and the reflection image is compounded over 360 degrees to create sub-mm resolution in plane.</p></div><div><h3>Methods</h3><p>The physics of ultrasound scattering requires 3D modeling and the concomitant high computational cost is ameliorated with a bespoke algorithm (paraxial approximation – discussed here) and Nvidia GPUs. The resulting reconstruction times are tabulated for clinical relevance. The resulting SOS map is used to create a refraction corrected reflection image at ∼3.6 MHz center frequency. The transmission data are highly redundant, collected over 360 degrees and at 2 mm levels by true matrix receiver arrays yielding 3D data.</p><p>The high resolution SOS and attenuation maps and reflection images are used in a segmentation algorithm that optimally utilizes this information to segment out glandular, ductal, connective tissue, fat and skin. These volumes are used to estimate breast density, an important correlate to cancer.</p></div><div><h3>Results</h3><p>Multiple SOS images of breast, knee and segmentations of breast glandular and ductal tissue are shown. Spearman <em>rho</em> is calculated between our volumetric breast density estimates and Volpara™ from mammograms, as 0.9332. Multiple timing results are shown and indicate the variability of the reconstruction times with breast size and type but are ∼30 minutes for average size breast. The timing results with the 3D algorithm indicate ∼60 minute reconstruction times for pediatrics with two Nvidia GPUs. Characteristic variations of the glandular and ductal volumes over time are shown. The SOS from QT images are compared with literature values.</p><p>The results of a multi-reader multi-case (MRMC) study are shown that compares the 3D UT with full field digital mammography and resulted in an average increase in ROC AUC of 10%. Orthopedic (knee) 3D UT images compared with MRI indicate regions of zero signal in the MRI are clearly displayed in the QT image.</p><p>Explicit representation of the acoustic field is shown, indicating its 3D nature. An image of in vivo breast with the chest muscle is shown and speed of sound agreement with literature values are tabulated. Reference is made to a recently published paper validating pediatric imaging.</p></div><div><h3>Conclusions</h3><p>The high Spearman <em>rho</em> indicates a monotonic (not necessarily linear) relation between our method and industry gold standard Volpara™ density. The acoustic field verifies the need for 3D modeling. The MRMC study, the orthopedic images, breast density study, and references, all indicate the clinical utility of the SOS
{"title":"Low frequency 3D transmission ultrasound tomography: technical details and clinical implications","authors":"James Wiskin , Bilal Malik , John Klock","doi":"10.1016/j.zemedi.2023.04.006","DOIUrl":"10.1016/j.zemedi.2023.04.006","url":null,"abstract":"<div><p>A novel 3D ultrasound tomographic (3D UT) method (called volography) that creates a speed of sound (SOS) map and a reflection modality that is co-registered are reviewed and shown to be artifact free even in the presence of high contrast and thus shown to be applicable for breast, orthopedic and pediatric clinical use cases. The 3D UT images are almost isotropic with mm resolution and the reflection image is compounded over 360 degrees to create sub-mm resolution in plane.</p></div><div><h3>Methods</h3><p>The physics of ultrasound scattering requires 3D modeling and the concomitant high computational cost is ameliorated with a bespoke algorithm (paraxial approximation – discussed here) and Nvidia GPUs. The resulting reconstruction times are tabulated for clinical relevance. The resulting SOS map is used to create a refraction corrected reflection image at ∼3.6 MHz center frequency. The transmission data are highly redundant, collected over 360 degrees and at 2 mm levels by true matrix receiver arrays yielding 3D data.</p><p>The high resolution SOS and attenuation maps and reflection images are used in a segmentation algorithm that optimally utilizes this information to segment out glandular, ductal, connective tissue, fat and skin. These volumes are used to estimate breast density, an important correlate to cancer.</p></div><div><h3>Results</h3><p>Multiple SOS images of breast, knee and segmentations of breast glandular and ductal tissue are shown. Spearman <em>rho</em> is calculated between our volumetric breast density estimates and Volpara™ from mammograms, as 0.9332. Multiple timing results are shown and indicate the variability of the reconstruction times with breast size and type but are ∼30 minutes for average size breast. The timing results with the 3D algorithm indicate ∼60 minute reconstruction times for pediatrics with two Nvidia GPUs. Characteristic variations of the glandular and ductal volumes over time are shown. The SOS from QT images are compared with literature values.</p><p>The results of a multi-reader multi-case (MRMC) study are shown that compares the 3D UT with full field digital mammography and resulted in an average increase in ROC AUC of 10%. Orthopedic (knee) 3D UT images compared with MRI indicate regions of zero signal in the MRI are clearly displayed in the QT image.</p><p>Explicit representation of the acoustic field is shown, indicating its 3D nature. An image of in vivo breast with the chest muscle is shown and speed of sound agreement with literature values are tabulated. Reference is made to a recently published paper validating pediatric imaging.</p></div><div><h3>Conclusions</h3><p>The high Spearman <em>rho</em> indicates a monotonic (not necessarily linear) relation between our method and industry gold standard Volpara™ density. The acoustic field verifies the need for 3D modeling. The MRMC study, the orthopedic images, breast density study, and references, all indicate the clinical utility of the SOS","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"33 3","pages":"Pages 427-443"},"PeriodicalIF":2.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/90/c2/main.PMC10517404.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10300659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-01DOI: 10.1016/j.zemedi.2023.04.010
Carl D. Herickhoff , Rob van Schaijk
Capacitive micromachined ultrasonic transducer (cMUT) technology has steadily advanced since its advent in the mid-1990’s. Though cMUTs have not supplanted piezoelectric transducers for medical ultrasound imaging to date, researchers and engineers are continuing to improve cMUTs and leverage unique cMUT characteristics toward new applications. While not intended to be an exhaustive review of every aspect of cMUT state-of-the-art, this article provides a brief overview of cMUT benefits, challenges, and opportunities, as well as recent progress in cMUT research and translation.
{"title":"cMUT technology developments","authors":"Carl D. Herickhoff , Rob van Schaijk","doi":"10.1016/j.zemedi.2023.04.010","DOIUrl":"10.1016/j.zemedi.2023.04.010","url":null,"abstract":"<div><p>Capacitive micromachined ultrasonic transducer (cMUT) technology has steadily advanced since its advent in the mid-1990’s. Though cMUTs have not supplanted piezoelectric transducers for medical ultrasound imaging to date, researchers and engineers are continuing to improve cMUTs and leverage unique cMUT characteristics toward new applications. While not intended to be an exhaustive review of every aspect of cMUT state-of-the-art, this article provides a brief overview of cMUT benefits, challenges, and opportunities, as well as recent progress in cMUT research and translation.</p></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"33 3","pages":"Pages 256-266"},"PeriodicalIF":2.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/27/7f/main.PMC10517396.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10627483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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