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
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
Objectives Functional development of the fetal cardiac autonomic nervous system (cANS) plays a key role in fetal maturation and can be assessed through fetal heart rate variability (fHRV)-analysis,... Show moreObjectives Functional development of the fetal cardiac autonomic nervous system (cANS) plays a key role in fetal maturation and can be assessed through fetal heart rate variability (fHRV)-analysis, with each HRV parameter representing different aspects of cANS activity. Current available techniques, however, are unable to assess the fHRV parameters accurately throughout the whole pregnancy. This study aims to test the feasibility of color tissue Doppler imaging (cTDI) as a new ultrasound technique for HRV analysis. Secondly, we explored time trends of fHRV parameters using this technique.Methods 18 healthy singleton fetuses were examined sequentially every 8 weeks from 10 weeks GA onwards. From each examination, 3 cTDI recordings of the four-chamber view of 10 seconds were retrieved to determine accurate beat-to-beat intervals. The fHRV parameters SDNN, RMSSD, SDNN/RMSSD, and pNN10, each representing different functional aspects of the cANS, were measured, and time trends during pregnancy were explored using spline functions within a linear mixed-effects model.Results In total, 77% (95% Cl 66-87%) of examinations were feasible for fHRV analysis from the first trimester onwards, which is a great improvement compared to other techniques. The technique is able to determine different maturation rates of the fHRV parameters, showing that cANS function, presumably parasympathetic activity, establishes around 20 weeks GA and matures rapidly until 30 weeks GA.Conclusions This is the first study able to assess cANS function through fHRV analysis from the first trimester onwards. The use of cTDI to determine beat-to-beat intervals seems feasible in just 3 clips of 10 seconds, which holds promise for future clinical use in assessing fetal well-being. Show less
Meershoek, P.; Berg, N.S. van den; Lutjeboer, J.; Burgmans, M.C.; Meer, R.W. van der; Rijswijk, C.S.P. van; ... ; Leeuwen, F.W.B. van 2021
Purpose: The goal of our study was to determine the influence of ultrasound (US)-coupled volume navigation on the use of computed tomography (CT) during minimally-invasive radiofrequency and... Show morePurpose: The goal of our study was to determine the influence of ultrasound (US)-coupled volume navigation on the use of computed tomography (CT) during minimally-invasive radiofrequency and microwave ablation procedures of liver lesions.Method: Twenty-five patients with 40 liver lesions of different histological origin were retrospectively analysed. Lesions were ablated following standard protocol, using 1) conventional US-guidance, 2) manual registered volume navigation (mVNav), 3) automatic registered (alpha VNav) or 4) CT-guidance. In case of ultrasonographically inconspicuous lesions, conventional US-guidance was abandoned and mVNav was used. If mVNav was also unsuccessful, the procedure was either continued with alpha VNav or CT-guidance. The number, size and location of the lesions targeted using the different approaches were documented.Results: Of the 40 lesions, sixteen (40.0 %) could be targeted with conventional US-guidance only, sixteen (40.0 %) with mVNav, three (7.5 %) with aVNav and five (12.5 %) only through the use of CT-guidance. Of the three alternatives (mVNav, alpha VNav and CT only) the mean size of the lesions targeted using mVNav (9.1 +/- 4.6 mm) was significantly smaller from those targeted using US-guidance only (20.4 +/- 9.4 mm; p < 0.001). The location of the lesions did not influence the selection of the modality used to guide the ablation.Conclusions: In our cohort, mVNav allowed the ablation procedure to become less dependent on the use of CT. mVNav supported the ablation of lesions smaller than those that could be ablated with US only and doubled the application of minimally-invasive US-guided ablations. 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
This thesis focuses on epidemiological studies of hand OA in secondary care, erosive OA as a subset of hand OA and the added value of imaging in hand OA to understand better the pathophysiology of... Show moreThis thesis focuses on epidemiological studies of hand OA in secondary care, erosive OA as a subset of hand OA and the added value of imaging in hand OA to understand better the pathophysiology of hand OA and seek for opportunities to define progression in an earlier stage. Chapter 2 gives an overview about the current knowledge on hand OA and it is clear that hand OA is a prevalent, heterogeneous disorder (including several hand OA subsets) that can cause considerable pain and disability. Much less is known about the risk factors of progression in hand OA. Moderate evidence for an abnormal scintigram at baseline was found as a risk factor for radiographic progression in a systematic review as described in chapter 3. In rheumatology practice, the most prevalent phenotype of OA is hand OA as depicted in chapter 4. This symptomatic population experience a substantial lower health-related quality of life compared to the general population. The collaborations with the Rotterdam Study and NorStOP Study (chapter 5, 6, 7) revealed that 2.8% of the general population rising to 10.2% in the symptomatic population is affected by erosive disease in the interphalangeal joints (IPJs). Furthermore, erosions are not present in IPJs only and prevalence of erosive disease in 1st carpometacarpal joints (CMCJs) is also given. Persons with erosive OA in the interphalangeal joints report more pain and functional limitations, however to a lesser extent than persons with other rheumatic inflammatory diseases. Inflammation does play a role in OA joints with erosions, as assessed with Power Doppler Signal, greyscale synovitis and effusion on ultrasound (chapter 8). Also in OA joints without erosions, inflammatory signs are visible on ultrasound (chapter 9). Regarding other imaging modalities used in hand OA research, quantitative joint space width (JSW) measurements in hand OA joints have been shown to be associated with self-reported pain, functional ability and structural abnormalities (chapter 10), whereas features on Magnetic Resonance Imaging (MRI, such as abnormal collateral ligaments and bone marrow lesions) are also associated with pain upon palpation in individual joints (chapter 11). Finally, the health-related quality of life in hand OA patients in rheumatology practice can be improved with a protocol-led consultation about increasing the use of helping aids and acetaminophen given by a clinical nurse specialist (chapter 12). Show less
This thesis describes the prevalence rates of testicular microlithiasis in symptomatic, asymptomatic boys and in boys with Down syndrome. We advise regular self-examination from the age of 15 in... Show moreThis thesis describes the prevalence rates of testicular microlithiasis in symptomatic, asymptomatic boys and in boys with Down syndrome. We advise regular self-examination from the age of 15 in boys with testicular microlithiasis and annual ultrasound in boys with Down syndrome. Furthermore, normative values of testicular volume measured by ultrasound and the volume of retractile testes are described. The volumes for the boys with retractile testes were significantly smaller than normative values. Finally, testicular growth in boys with acquired undescended testis managed with a conservative attitude and an overview of acquired undescended testis is presented. We concluded that acquired undescended testis has a 77.5% tendency of spontaneous descent at puberty and, after spontaneous descent as well as after pubertal orchidopexy, long-term testicular growth is within the normal range. We speculate that acquired undescended testis is in fact congenital: it is the result of a short funiculus at birth, which allows a low scrotal position early in life. However, as the boy grows, the testis evolves into an undescended state. As a result of gonadal stimulation at puberty, spontaneous descent occurs in three of every four cases. Show less
