Objectives Percutaneous radiofrequency ablation (RFA) is stated as a treatment option for renal cell carcinoma (RCC) smaller than 4 cm (T1a). Microwave ablation (MWA) is a newer technique and is... Show moreObjectives Percutaneous radiofrequency ablation (RFA) is stated as a treatment option for renal cell carcinoma (RCC) smaller than 4 cm (T1a). Microwave ablation (MWA) is a newer technique and is still considered experimental in some guidelines. The objective of this study was to compare the safety and efficacy of RFA and MWA for the treatment of RCC. Methods Patients with T1a RCC treated by RFA or MWA in two referral centers were retrospectively analyzed. Patient records were evaluated to generate mRENAL nephrometry scores. Local tumor progression (LTP) was considered when new (recurrence) or residual tumor enhancement within/adjacent to the ablation zone was objectified. Differences in LTP-free interval (residual + recurrence) between ablation techniques were assessed with Cox proportional hazards models and propensity score (PS) methods. Results In 164 patients, 87 RFAs and 101 MWAs were performed for 188 RCCs. The primary efficacy rate was 92% (80/87) for RFA and 91% (92/101) for MWA. Sixteen patients had residual disease (RFA (n = 7), MWA (n = 9)) and 9 patients developed recurrence (RFA (n = 7), MWA (n = 2)). LTP-free interval was significantly worse for higher mRENAL nephrometry scores. No difference in LTP-free interval was found between RFA and MWA in a model with inverse probability weighting using PS (HR = 0.99, 95% CI 0.35-2.81, p = 0.98) and in a PS-matched dataset with 110 observations (HR = 0.82, 95% CI 0.16-4.31, p = 0.82). Twenty-eight (14.9%) complications (Clavien-Dindo grade I-IVa) occurred (RFA n = 14, MWA n = 14). Conclusion Primary efficacy for ablation of RCC is high for both RFA and MWA. No differences in efficacy and safety were observed between RFA and MWA. Show less
Today, Computed Tomography (CT) is a widely established technique to visualize pathological changes in archaeological human remains. The high definition of the current scanners allow for even small... Show moreToday, Computed Tomography (CT) is a widely established technique to visualize pathological changes in archaeological human remains. The high definition of the current scanners allow for even small lesions to be visualized, therefore giving osteoarchaeologists a powerful tool to investigate disease in the past.The study of chronic maxillary sinusitis (CMS) has received significant attention in the past years as the presence of CMS is generally considered indicative or air quality. We discuss here the methodological implications of using CT scans for diagnosing CMS in contrast to classical endoscopical observation. A total of 32 crania from the Dutch post-medieval rural village of Middenbeemster (AD 1829-1866) were examined both endoscopically and through CT scans. Criteria for identifying CMS included presence of bone spicules and pitting on the sinus walls. 12 cases of CMS were identified endoscopically, and 19 through CT scanning. Statistical analysis revealed no significant differences in scoring CMS endoscopically or through radiographic imaging (τb=0.246, p=0.170). When investigating differences among features, no statistical difference was found between spicules observed through macroscopical analysis and computed tomography respectively (τb=0.246, p=0.170). The same analysis, however, revealed a statistically significant difference in endoscopically-assessed and CT-observed pitting (τb=0.374, p=0.037). Our results suggest that diagnosis of CMS on human skeletal remains can be confidently performed both through endoscopical and radiological analysis, albeit delivering better performances in scoring bone formation in contrast to bone resorption. Further research is being considered to fully explore the role of computed tomography in the study of CMS. Show less
Introduction: Early detection of large vessel occlusion (LVO) is essential to facilitate fast endovascular treatment. CT angiography (CTA) is used to detect LVO in suspected stroke patients. We... Show moreIntroduction: Early detection of large vessel occlusion (LVO) is essential to facilitate fast endovascular treatment. CT angiography (CTA) is used to detect LVO in suspected stroke patients. We aimed to assess the accuracy of CTA evaluations in daily clinical practice in a large cohort of suspected stroke patients. Patients and methods: We used data from the PRESTO study, a multicenter prospective observational cohort study that included suspected stroke patients between August 2018 and September 2019. Baseline CTAs were re-evaluated by an imaging core laboratory and compared to the local assessment. LVO was defined as an occlusion of the intracranial internal carotid artery, M1 segment, or basilar artery. Medium vessel occlusion (MeVO) was defined as an A1, A2, or M2 occlusion. We calculated the accuracy, sensitivity, and specificity to detect LVO and LVO+MeVO, using the core laboratory evaluation as reference standard. Results: We included 656 patients. The core laboratory detected 89 LVOs and 74 MeVOs in 155 patients. Local observers missed 6 LVOs (7%) and 28 MeVOs (38%), of which 23 M2 occlusions. Accuracy of LVO detection was 99% (95% CI: 98-100%), sensitivity 93% (95% CI: 86-97%), and specificity 100% (95% CI: 99-100%). Accuracy of LVO+MeVO detection was 95% (95% CI: 93-96%), sensitivity 79% (95% CI: 72-85%), and specificity 99% (95% CI: 98-100%). Discussion and Conclusion: CTA evaluations in daily clinical practice are highly accurate and LVOs are adequately recognized. The detection of MeVOs seems more challenging. The evolving EVT possibilities emphasize the need to improve CTA evaluations in the acute setting. Show less
Background It is estimated that 20-50% of all radiological examinations are of low value. Many attempts have been made to reduce the use of low-value imaging. However, the comparative effectiveness... Show moreBackground It is estimated that 20-50% of all radiological examinations are of low value. Many attempts have been made to reduce the use of low-value imaging. However, the comparative effectiveness of interventions to reduce low-value imaging is unclear. Thus, the objective of this systematic review was to provide an overview and evaluate the outcomes of interventions aimed at reducing low-value imaging. Methods An electronic database search was completed in Medline - Ovid, Embase-Ovid, Scopus, and Cochrane Library for citations between 2010 and 2020. The search was built from medical subject headings for Diagnostic imaging/Radiology, Health service misuse or medical overuse, and Health planning. Keywords were used for the concept of reduction and avoidance. Reference lists of included articles were also hand-searched for relevant citations. Only articles written in English, German, Danish, Norwegian, Dutch, and Swedish were included. The Mixed Methods Appraisal Tool was used to appraise the quality of the included articles. A narrative synthesis of the final included articles was completed. Results The search identified 15,659 records. After abstract and full-text screening, 95 studies of varying quality were included in the final analysis, containing 45 studies found through hand-searching techniques. Both controlled and uncontrolled before-and-after studies, time series, chart reviews, and cohort studies were included. Most interventions were aimed at referring physicians. Clinical practice guidelines (n = 28) and education (n = 28) were most commonly evaluated interventions, either alone or in combination with other components. Multi-component interventions were often more effective than single-component interventions showing a reduction in the use of low-value imaging in 94 and 74% of the studies, respectively. The most addressed types of imaging were musculoskeletal (n = 26), neurological (n = 23) and vascular (n = 16) imaging. Seventy-seven studies reported reduced low-value imaging, while 3 studies reported an increase. Conclusions Multi-component interventions that include education were often more effective than single-component interventions. The contextual and cultural factors in the health care systems seem to be vital for successful reduction of low-value imaging. Further research should focus on assessing the impact of the context in interventions reducing low-value imaging and how interventions can be adapted to different contexts. Show less
Su, R.S.; Cornelissen, S.A.P.; Sluijs, M. van der; Es, A.C.G.M. van; Zwam, W.H. van; Dippel, D.W.J.; ... ; Walsum, T. van 2021
The Thrombolysis in Cerebral Infarction (TICI) score is an important metric for reperfusion therapy assessment in acute ischemic stroke. It is commonly used as a technical outcome measure after... Show moreThe Thrombolysis in Cerebral Infarction (TICI) score is an important metric for reperfusion therapy assessment in acute ischemic stroke. It is commonly used as a technical outcome measure after endovascular treatment (EVT). Existing TICI scores are defined in coarse ordinal grades based on visual inspection, leading to inter- and intra-observer variation. In this work, we present autoTICI, an automatic and quantitative TICI scoring method. First, each digital subtraction angiography (DSA) acquisition is separated into four phases (non-contrast, arterial, parenchymal and venous phase) using a multi-path convolutional neural network (CNN), which exploits spatio-temporal features. The network also incorporates sequence level label dependencies in the form of a state-transition matrix. Next, a minimum intensity map (MINIP) is computed using the motion corrected arterial and parenchymal frames. On the MINIP image, vessel, perfusion and background pixels are segmented. Finally, we quantify the autoTICI score as the ratio of reperfused pixels after EVT. On a routinely acquired multi-center dataset, the proposed autoTICI shows good correlation with the extended TICI (eTICI) reference with an average area under the curve (AUC) score of 0.81. The AUC score is 0.90 with respect to the dichotomized eTICI. In terms of clinical outcome prediction, we demonstrate that autoTICI is overall comparable to eTICI. Show less
Existing quantitative imaging biomarkers (QIBs) are associated with known biological tissue characteristics and follow a well-understood path of technical, biological and clinical validation before... Show moreExisting quantitative imaging biomarkers (QIBs) are associated with known biological tissue characteristics and follow a well-understood path of technical, biological and clinical validation before incorporation into clinical trials. In radiomics, novel data-driven processes extract numerous visually imperceptible statistical features from the imaging data with no a priori assumptions on their correlation with biological processes. The selection of relevant features (radiomic signature) and incorporation into clinical trials therefore requires additional considerations to ensure meaningful imaging endpoints. Also, the number of radiomic features tested means that power calculations would result in sample sizes impossible to achieve within clinical trials. This article examines how the process of standardising and validating data-driven imaging biomarkers differs from those based on biological associations. Radiomic signatures are best developed initially on datasets that represent diversity of acquisition protocols as well as diversity of disease and of normal findings, rather than within clinical trials with standardised and optimised protocols as this would risk the selection of radiomic features being linked to the imaging process rather than the pathology. Normalisation through discretisation and feature harmonisation are essential pre-processing steps. Biological correlation may be performed after the technical and clinical validity of a radiomic signature is established, but is not mandatory. Feature selection may be part of discovery within a radiomics-specific trial or represent exploratory endpoints within an established trial; a previously validated radiomic signature may even be used as a primary/secondary endpoint, particularly if associations are demonstrated with specific biological processes and pathways being targeted within clinical trials. Show less
Kuijf, H.J.; Biesbroek, J.M.; Bresser, J. de; Heinen, R.; Andermatt, S.; Bento, M.; ... ; Biessels, G.J. 2019
Despite one might intuitively think that blood inflows inside the human heart in a straight path, direct imaging of cardiac blood flow showed that, actually, cardiac blood inflows in a swirling... Show moreDespite one might intuitively think that blood inflows inside the human heart in a straight path, direct imaging of cardiac blood flow showed that, actually, cardiac blood inflows in a swirling motion forming what is called vortex flow pattern. In fact, blood inflow forms a pair of counter-rotating vortices distal to the mitral valve inside the heart. In three-dimensions, this pair of vortices forms a ring-like vortex: a vortex ring. This thesis revealed the three-dimensional form and time evolution of such vortex ring flow in the human heart in health and disease. This was achieved using cutting-edge 4D Flow MRI in-vivo imaging technology and developments of novel advanced methods integrating image and applied fluid mechanics concepts enabling characterization, quantification and automatic identification of heart’s vortex flow. In this thesis, a novel framework was developed allowing for the first noninvasive assessment of intra-cardiac viscous energy loss. This thesis showed that alteration in cardiac vortex ring flow properties, due to heart disease, can result in 2-4 fold increase in viscous energy loss in the left ventricle. As such, heart’s vortex flow could be an efficient mechanism of energy loss minimization in healthy hearts and might act as a biomarker of cardiac health. Show less
Cochlear implants, which provide hearing for the deaf, have evolved in recent decades from single-channel implants to multichannel implants that are able to restore speech perception abilities for... Show moreCochlear implants, which provide hearing for the deaf, have evolved in recent decades from single-channel implants to multichannel implants that are able to restore speech perception abilities for many. Cochlear implantation has eased communication with the hearing world and has greatly facilitated language development in children. However, considerable variation in performance exists among subjects, and speech perception in background noise continues to be troublesome for most, if not all cochlear implant recipients. Cochlear implants form an interface between an audio signal and the nerve fibers of the deaf ear. This thesis focuses on optimizing the way in which the incoming speech signal is transferred to the excitable neural elements in the cochlea. Show less
The general objective of this thesis was to investigate new (quantitative) MR techniques and MR markers in the light of both AD and cerebral aging. The quantitative MR techniques that we used were... Show moreThe general objective of this thesis was to investigate new (quantitative) MR techniques and MR markers in the light of both AD and cerebral aging. The quantitative MR techniques that we used were MTI, tCBF and WSS measurements. The new markers we studied were cerebral microbleeds and iron accumulation in the basal ganglia. In chapter 2 we investigated whether MTI changes could be detected in the GM, WM or both in patients suffering from MCI or AD. Using MTI we found evidence for structural brain changes in both GM and WM of patients with MCI and AD. Furthermore, these MTI changes were related to cognitive impairment as expressed by the mini mental state examination (MMSE) score. These findings imply that cerebral changes can be detected in both GM and WM even before patients are clinically demented. The finding of MTI changes in the GM might relate to classical AD type pathology, whereas WM MTI changes could indicate concomitant vascular pathology. The findings in chapter 2 raised the question of how the MTI changes found in this study are distributed over the GM and WM. This was investigated in chapter 3. In this study we showed that brain damage, as detected by MTI, is widespread over the lobes in both AD and MCI patients whereas GM damage is more focally present in the temporal and frontal lobe of MCI patients. These findings are compatible with the knowledge that GM damage originates from the temporal lobe in AD. This interpretation is further supported by the observed independent association between temporal GM peak height and cognitive decline. MTI changes were found in all four lobes of the MCI patients investigated in this study and show the involvement of a diffuse process affecting the WM even before patients are clinically demented, a finding potentially explained by the presence of diffuse vascular pathology. Chapter 4 shows that the tCBF is strongly associated with parenchymal volume rather than age and, although much weaker, with the severity of WMHs. Although the association between tCBF and parenchyma volume seems straightforward, this finding has important implications for future studies. Volume flow measurements should be corrected for parenchymal volume ratherthan age in all future studies in which flow measurements are being used as a diagnostic tool. In addition, studies including elderly patients or patients with a pathological increase of WMHs, such as diabetic type II subjects, should also correct their tCBF measurements for WMH volumes. Chapter 5 shows that hemodynamic conditions of the carotid and basilar arteries, as expressed in lower WSS parameters, are worse in both MCI and AD compared to controls. In addition, the WSS parameters were found to correlate strongly with cognition. Again, this study is additional evidence for an important role of vascular pathology in the development of AD. In chapter 6, we found a high prevalence of microbleeds in a population of patients suffering from vascular disease or at high risk of developing this condition. Age, hypertension and WMH were the most important risk factors for microbleeds, especially when located in the cortico-subcortical junction and basal ganglia. Regarding the associations between the presence and location of microbleeds on the one hand and parameters of cognitive functioning on the other, chapter 7 shows that microbleeds located infratentorially are associated with impaired cognitive functioning in the aging population with increased vascular risk factors. This suggests that in elderly individuals microbleeds in the posterior fossa should be considered a sign of small vessel disease with potential functional consequences. The semi-quantative scale for scoring basal ganglia hypo-intensity on T2*- weighted imaging presented in chapter 8 was associated with markers of neurodegeneration. This study showed that low signal intensity of the caudate nucleus T2*-weighted MR is a frequent finding which is associated with more cerebral atrophy, a higher load of WMH and a higher load of invisible changes in both cortical GM and NAWM non-demented elderly. Furthermore, hypo- intensity limited to the globus pallidus and putamen was not associated with any of these parameters of neurodegeneration. In chapter 9 we present a method for automated detection and classification of hypo-intense regions on T2-weighted MR images of the basal ganglia. In this chapter we not only show an association between basal ganglia hypo-intensity and cardiovascular risk factors but also with measures of cognitive functioning. From this we conclude that hypo-intensity of the basal ganglia on T2-weighted MR is not only a radiological finding accompanying cerebral aging but also an independent marker of neurodegeneration. Show less
The aim of this thesis was to develop methods to enable the use of 7 Tesla MRI in clinical practice. A number of technical developments have been performed to facilitate clinical studies and to... Show moreThe aim of this thesis was to develop methods to enable the use of 7 Tesla MRI in clinical practice. A number of technical developments have been performed to facilitate clinical studies and to achieve the full potential of high field. Studies have been performed for imaging of different anatomies of the human body, including visualization of the right coronary artery and high resolution imaging of the brain in patients with neurodegenerative diseases Show less
