Objective: Conventionally, ocular proton therapy (PT) is planned using measurements obtained by an ophthalmologist using ultrasound, fundoscopy, biometry, and intraoperative assessments. Owing to... Show moreObjective: Conventionally, ocular proton therapy (PT) is planned using measurements obtained by an ophthalmologist using ultrasound, fundoscopy, biometry, and intraoperative assessments. Owing to the recent advances in magnetic resonance imaging (MRI) of uveal melanoma (UM), it is possible to acquire high-resolution 3-dimensional images of the eye, providing the opportunity to incorporate MRI in ocular PT planning. In this study, we described how these measurements can be obtained using MRI, compared the MRI-based measurements with conventional ophthalmic measurements, and identified potential pitfalls for both modalities. Design: Cross-sectional study. Subjects: Data from 23 consecutive patients with UM treated with PT were retrospectively evaluated. Methods: Magnetic resonance imaging-based measurements of axial length, tumor height and basal diameter, and marker-tumor distances were compared with the conventional ophthalmic measurements, and discrepancies were evaluated in a multidisciplinary setting. Main Outcome Measures: Tumor prominence and basal diameters on MRI and ultrasound, axial length on MRI and biometry, tumor-marker distances on MRI and measured intraoperatively. Results: The mean absolute differences of the tumor height and basal diameter measurements between ultrasound and MRI were 0.57 mm and 1.44 mm, respectively. Larger absolute differences in height and basal diameter were observed when the full tumor extent was not visible on ultrasound (0.92 mm and 1.67 mm, respectively) compared with when the full tumor extent was visible (0.44 mm and 1.15 mm, respectively). When the full tumor was not visible on ultrasound, MRI was considered more reliable. Tumor-marker distances measured using MRI and intraoperative techniques differed < 1 mm in 55% of the markers. For anteriorly located and mushroom-shaped tumors (25% of the markers), MRI provided more accurate measurements. In flat UM (15% of the markers), however, it was difficult to delineate the tumor on MRI. The mean absolute difference in axial length between optical biometry and MRI was 0.50 mm. The presence of the tumor was found to influence optical biometry in 15 of 22 patients; the remaining patients showed a better agreement (0.30 mm). Magnetic resonance imaging-based biometry was considered more reliable in patients with UM. Conclusions: Magnetic resonance imaging allowed for the 3-dimensional assessment of the tumor and surrounding tissue. In specific patients, it provided a more reliable measurement of axial length, tumor dimensions, and marker-tumor distances and could contribute to a more accurate treatment planning. Never-theless, a combined evaluation remains advised, especially for flat UM. Show less
In this thesis I investigate new ways to use MRI (magnetic resonance imaging) for the diagnosis, treatment and follow-up of uveal melanoma (UM) patients, mainly in relation to the planning of... Show moreIn this thesis I investigate new ways to use MRI (magnetic resonance imaging) for the diagnosis, treatment and follow-up of uveal melanoma (UM) patients, mainly in relation to the planning of proton beam therapy. Proton beam therapy is performed while sitting whereas MRI scans are scanned in prone position. In chapter 2 I have shown that the shape of the eye and tumor are not affected by the change in position. During treatment planning the tumor shape needs to be determined. This can be done by drawing the tumor on MRI. In chapter 3 I have shown that the variance between segmentations performed by different doctors are on average smaller then 0.4mm. As MRI based planning is not yet available for UM patients we have developed an MRI protocol to support the current model based treatment planning software with MRI based measurements. In chapter 4 I compare these MRI based measurements with conventional measurements and show that MRI measurements are comparable and sometimes even better. A common side effect of UM is retinal detachment. This is sometimes treated with silicon oil. Unfortunately ultrasound imaging is not possible in these patients. In chapter 5 I describe and evaluate a MRI protocol to imaging these tumors with MRI. Finally, MRI can also provide information about tissue and functional characteristics. In chapter 6 I present a method to overcome eye specific challenges in the quantitative analysis of perfusion weighted MRI. Show less
Background and Purpose: Three-dimensional (3D) Magnetic Resonance Imaging (MRI) is increasingly used to complement conventional two-dimensional ultrasound in the assessment of tumour dimension... Show moreBackground and Purpose: Three-dimensional (3D) Magnetic Resonance Imaging (MRI) is increasingly used to complement conventional two-dimensional ultrasound in the assessment of tumour dimension measurement of uveal melanoma. However, the lack of definitions of the 3D measurements of these tumour dimensions hinders further adaptation of MRI in ocular radiotherapy planning. In this study, we composed 3D MR-based definitions of tumour prominence and basal diameter and compared them to conventional ultrasound. Materials and methods: Tumours were delineated on 3DT2 and contrast-enhanced 3DT1 (T1gd) MRI for 25 pa-tients. 3D definitions of tumour prominence and diameter were composed and evaluated automatically on the T1gd and T2 contours. Automatic T1gd measurements were compared to manual MRI measurements, to auto-matic T2 measurements and to manual ultrasound measurements. Results: Prominence measurements were similar for all modalities (median absolute difference 0.3 mm). Auto-matic T1gd diameter measurements were generally larger than manual MRI, automatic T2 and manual ultra-sound measurements (median absolute differences of 0.5, 1.6 and 1.1 mm respectively), mainly due to difficulty defining the axis of the largest diameter. Largest differences between ultrasound and MRI for both prominence and diameter were found in anteriorly located tumours (up to 1.6 and 4.5 mm respectively), for which the tumour extent could not entirely be visualized with ultrasound. Conclusions: The proposed 3D definitions for tumour prominence and diameter agreed well with ultrasound measurements for tumours for which the extent was visible on ultrasound. 3D MRI measurements generally provided larger diameter measurements than ultrasound. In anteriorly located tumours, the MRI measurements were considered more accurate than conventional ultrasound. Show less
Hesse, L.S.; Aliasi, M.; Moser, F.; Haak, M.C.; Xie, W.D.; Jenkinson, M.; ... ; INTERGROWTH-21st Consortium 2022
The quantification of subcortical volume development from 3D fetal ultrasound can provide important diagnostic information during pregnancy monitoring. However, manual segmentation of subcortical... Show moreThe quantification of subcortical volume development from 3D fetal ultrasound can provide important diagnostic information during pregnancy monitoring. However, manual segmentation of subcortical structures in ultrasound volumes is time-consuming and challenging due to low soft tissue contrast, speckle and shadowing artifacts. For this reason, we developed a convolutional neural network (CNN) for the automated segmentation of the choroid plexus (CP), lateral posterior ventricle horns (LPVH), cavum septum pellucidum et vergae (CSPV), and cerebellum (CB) from 3D ultrasound. As ground-truth labels are scarce and expensive to obtain, we applied few-shot learning, in which only a small number of manual annotations (n = 9) are used to train a CNN. We compared training a CNN with only a few individually annotated volumes versus many weakly labelled volumes obtained from atlas-based segmentations. This showed that segmentation performance close to intra-observer variability can be obtained with only a handful of manual annotations. Finally, the trained models were applied to a large number (n = 278) of ultrasound image volumes of a diverse, healthy population, obtaining novel US-specific growth curves of the respective structures during the second trimester of gestation. Show less
Adriaensen, M.E.; Dalili, D.; Lamb, H.; Ricci, P. 2022
Background The current global pandemic of Coronavirus Disease 2019 (COVID-19) has profoundly impacted medical practitioners worldwide. This survey was formed by the Radiology Section of the... Show moreBackground The current global pandemic of Coronavirus Disease 2019 (COVID-19) has profoundly impacted medical practitioners worldwide. This survey was formed by the Radiology Section of the European Union of Medical Specialists (UEMS) to establish the use of personal protective equipment (PPE) by European radiologists committed to providing face-to-face ultrasound services after the first few months of the COVID-19 global pandemic. Results The results showed a heterogeneous picture within Europe regarding PPE used by European radiologists providing face-to-face ultrasound services. Ranging from full protection including full limb protection and double gloves to no PPE at all. In general, European radiologists were using more PPE when providing face-to-face ultrasound services in COVID-19 positive patients than in COVID-19 asymptomatic patients. In many member countries of the Radiology Section of the UEMS (19/30), there were no national guidelines with regard to the use of PPE by healthcare professionals committed to providing face-to-face ultrasound services. Conclusions Our results showed that harmonization on a European level regarding the recommended use of PPE for European radiologists providing face-to-face ultrasound services is lacking. When the position statements and best practice recommendations on standards in ultrasound are revised, we recommend adding a paragraph on PPE. Show less
Geertsema, D.; Meinardi, J.E.; Kempink, D.R.J.; Fiocco, M.; Sande, M.A.J. van de 2019
ObjectiveAneurysmal bone cysts (ABC) rarely present in soft tissue locations (STABC). The 30 cases of STABC reported in the English literature were reviewed. Six new cases retrieved from the files... Show moreObjectiveAneurysmal bone cysts (ABC) rarely present in soft tissue locations (STABC). The 30 cases of STABC reported in the English literature were reviewed. Six new cases retrieved from the files of the Netherlands Committee on Bone Tumors were compared to the six cases described in the radiological literature.Materials and methodsImaging studies and histopathology of six new STABC cases were reviewed. Follow-up was recorded with respect to local recurrence. FISH for USP6 rearrangement and/or anchored multiplex PCR-based targeted NGS using Archer FusionPlex Sarcoma Panel were attempted.ResultsOn imaging, the six STABC cases presented as a solid or multicystic intramuscular soft tissue mass, usually with thin peripheral mineralized bone shell. On MRI, perilesional edema was visualized in nearly all cases. Fluid-fluid levels were observed in one case. All lesions had the distinct histologic features of STABC. In three cases suitable for NGS, the diagnosis of STABC was confirmed by a COL1A1-USP6 fusion gene. In one additional case, USP6 gene rearrangement was detected by FISH. After marginal excision, none of the six STABC recurred after a mean follow-up period of 50months (range, 39-187months).ConclusionsOn imaging, it can be difficult to discriminate between STABC and myositis ossificans. The presence of a thin bony shell and fluid-fluid levels can be helpful in discriminating these two entities. STABC is readily diagnosed after histopathologic examination of the resection specimen. STABC belongs to the spectrum of tumors with USP6 rearrangements, which includes ABC, myositis ossificans, and nodular fasciitis. Show less
Berg, R. van den; Ohrndorf, S.; Kortekaas, M.C.; Helm-van Mil, A.H.M. van der 2018
Atherosclerotic changes of the carotid artery are associated with elevated cardiovascular risk. Non-invasive imaging studies of the artery can provide information on the presence or absence of... Show moreAtherosclerotic changes of the carotid artery are associated with elevated cardiovascular risk. Non-invasive imaging studies of the artery can provide information on the presence or absence of abnormalities. Although the techniques are extensively used in clinical research their implementation in common practice is not widespread. In this thesis the potential benefits and challenges of carotid imaging in clinical practice are studied. Ultrasound and magnetic resonance imaging are the two modalities of interest. The findings suggest that ultrasound can be performed by the clinician in a routine outpatient setting. Clinicians are able to detect atherosclerotic plaques but not intima-media thickness. Plaques are highly prevalent in asymptomatic primary prevention patients. Magnetic resonance imaging is a new highly reproducible modality but requires further clinical validation. Its utility in individual patient risk assessment is unclear and ultrasound validity cannot be extrapolated to magnetic resonance. The use of a combination of the two imaging modalities may allow for estimation of the lamina adventitia in vivo. Finally, interpretation of the imaging parameters must be done in conjunction with all cardiovascular risk factors and treatment decision should not be based on imaging results alone. Show less
Escoffre, J.M.; Derieppe, M.; Lammertink, B.; Bos, C.; Moonen, C. 2017
This thesis focuses on growth inhibition of small abdominal aortic aneurysms (AAA), which is a potentially lethal, pathological dilatation of 30 mm or more of the infrarenal aorta. The main... Show moreThis thesis focuses on growth inhibition of small abdominal aortic aneurysms (AAA), which is a potentially lethal, pathological dilatation of 30 mm or more of the infrarenal aorta. The main clinical challenges are currently: Can we predict aneurysm growth? Is it possible to keep small aneurysms small? Can we translate the preclinical evidence into a medical therapy? On theoretical grounds and preclinical data, doxycycline appears an excellent lead-candidate for the medical stabilization of growing AAA. However, this randomized placebo controlled multicentre trial revealed that doxycycline treatment did not inhibit aneurysm progression but increased the growth rate. These highly remarkable findings fundamentally challenge the current paradigm that inflammation per se is harmful in AAA progression. In this context, other findings of this thesis gain importance, showing that patients with diabetes mellitus have slower aneurysm growth and that aneurysm patients are more likely to develop COPD. The responsible pathophysiological mechanisms contain undoubtedly important clues, but have to be unraveled yet. Show less
Bartheld, M.B. von; Breda, A. van; Annema, J.T. 2014
Imaging subsurface structures with nanometer resolution has been a long-standing desire in science and industry. To obtain subsurface information one usually applies ultrasound, like e.g. in... Show moreImaging subsurface structures with nanometer resolution has been a long-standing desire in science and industry. To obtain subsurface information one usually applies ultrasound, like e.g. in echocardiography. Implementing ultrasound in an Atomic Force Microscope, a setup that is capable of imaging surfaces with atomic resolution, gives access to additional information. In particular, it is possible to image subsurface structures with nanometer resolution. However, it is not known why the subsurface structures become visible when applying ultrasound during the imaging with an Atomic Force Microscope. Based on a special excitation scheme, which makes use of two ultrasound excitations (one through the sample and one through the cantilever), Heterodyne Force Microscopy seems to be the most promising candidate for imaging deeply buried objects or structures with nanometer resolution. This thesis focuses on the poorly understood elements in Heterodyne Force Microscopy. We studied the ultrasound propagation in the sample, the dynamics of an ultrasonically excited cantilever near a sample that is also vibrating at a slightly diff erent frequency, and the generation of the heterodyne signal. The insight we gained in these matters allowed us to determine the contrast mechanism in a very well-de fined model sample, which contains gold nanoparticles buried in a soft polymer matrix. We show that the contrast in this system is determined by “friction at shaking nanoparticles”. Show less
