4,551 research outputs found

    A Review on Computer Aided Diagnosis of Acute Brain Stroke.

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    Amongst the most common causes of death globally, stroke is one of top three affecting over 100 million people worldwide annually. There are two classes of stroke, namely ischemic stroke (due to impairment of blood supply, accounting for ~70% of all strokes) and hemorrhagic stroke (due to bleeding), both of which can result, if untreated, in permanently damaged brain tissue. The discovery that the affected brain tissue (i.e., 'ischemic penumbra') can be salvaged from permanent damage and the bourgeoning growth in computer aided diagnosis has led to major advances in stroke management. Abiding to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, we have surveyed a total of 177 research papers published between 2010 and 2021 to highlight the current status and challenges faced by computer aided diagnosis (CAD), machine learning (ML) and deep learning (DL) based techniques for CT and MRI as prime modalities for stroke detection and lesion region segmentation. This work concludes by showcasing the current requirement of this domain, the preferred modality, and prospective research areas

    DEVELOPING NOVEL COMPUTER-AIDED DETECTION AND DIAGNOSIS SYSTEMS OF MEDICAL IMAGES

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    Reading medical images to detect and diagnose diseases is often difficult and has large inter-reader variability. To address this issue, developing computer-aided detection and diagnosis (CAD) schemes or systems of medical images has attracted broad research interest in the last several decades. Despite great effort and significant progress in previous studies, only limited CAD schemes have been used in clinical practice. Thus, developing new CAD schemes is still a hot research topic in medical imaging informatics field. In this dissertation, I investigate the feasibility of developing several new innovative CAD schemes for different application purposes. First, to predict breast tumor response to neoadjuvant chemotherapy and reduce unnecessary aggressive surgery, I developed two CAD schemes of breast magnetic resonance imaging (MRI) to generate quantitative image markers based on quantitative analysis of global kinetic features. Using the image marker computed from breast MRI acquired pre-chemotherapy, CAD scheme enables to predict radiographic complete response (CR) of breast tumors to neoadjuvant chemotherapy, while using the imaging marker based on the fusion of kinetic and texture features extracted from breast MRI performed after neoadjuvant chemotherapy, CAD scheme can better predict the pathologic complete response (pCR) of the patients. Second, to more accurately predict prognosis of stroke patients, quantifying brain hemorrhage and ventricular cerebrospinal fluid depicting on brain CT images can play an important role. For this purpose, I developed a new interactive CAD tool to segment hemorrhage regions and extract radiological imaging marker to quantitatively determine the severity of aneurysmal subarachnoid hemorrhage at presentation and correlate the estimation with various homeostatic/metabolic derangements and predict clinical outcome. Third, to improve the efficiency of primary antibody screening processes in new cancer drug development, I developed a CAD scheme to automatically identify the non-negative tissue slides, which indicate reactive antibodies in digital pathology images. Last, to improve operation efficiency and reliability of storing digital pathology image data, I developed a CAD scheme using optical character recognition algorithm to automatically extract metadata from tissue slide label images and reduce manual entry for slide tracking and archiving in the tissue pathology laboratories. In summary, in these studies, we developed and tested several innovative approaches to identify quantitative imaging markers with high discriminatory power. In all CAD schemes, the graphic user interface-based visual aid tools were also developed and implemented. Study results demonstrated feasibility of applying CAD technology to several new application fields, which has potential to assist radiologists, oncologists and pathologists improving accuracy and consistency in disease diagnosis and prognosis assessment of using medical image

    AUTOMATED MIDLINE SHIFT DETECTION ON BRAIN CT IMAGES FOR COMPUTER-AIDED CLINICAL DECISION SUPPORT

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    Midline shift (MLS), the amount of displacement of the brain’s midline from its normal symmetric position due to illness or injury, is an important index for clinicians to assess the severity of traumatic brain injury (TBI). In this dissertation, an automated computer-aided midline shift estimation system is proposed. First, a CT slice selection algorithm (SSA) is designed to automatically select a subset of appropriate CT slices from a large number of raw images for MLS detection. Next, ideal midline detection is implemented based on skull bone anatomical features and global rotation assumptions. For the actual midline detection algorithm, a window selection algorithm (WSA) is applied first to confine the region of interest, then the variational level set method is used to segment the image and extract the ventricle contours. With a ventricle identification algorithm (VIA), the position of actual midline is detected based on the identified right and left lateral ventricle contours. Finally, the brain midline shift is calculated using the positions of detected ideal midline and actual midline. One of the important applications of midline shift in clinical medical decision making is to estimate the intracranial pressure (ICP). ICP monitoring is a standard procedure in the care of severe traumatic brain injury (TBI) patients. An automated ICP level prediction model based on machine learning method is proposed in this work. Multiple features, including midline shift, intracranial air cavities, ventricle size, texture patterns, and blood amount, are used in the ICP level prediction. Finally, the results are evaluated to assess the effectiveness of the proposed method in ICP level prediction

    Postmortem radiological imaging of natural causes of death in adults – a review

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    Radiological findings of natural causes of death in adults in postmortem imaging are of enormous value for medicolegal investigation. Postmortem computed tomography (PMCT) in particular is increasingly used as a triage tool after external inspection and before a full autopsy. Forensic pathologists and radiologists commonly deal with a wide variety of deaths from natural causes. The most common encountered natural causes of death refer to the cardiovascular, central nervous, respiratory, gastrointestinal and metabolic system. This review provides an overview of the literature on postmortem imaging of the major natural causes of death in adults, categorized by organ systems

    Acute Stroke Care: Strategies For Improving Diagnostics

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    Stroke is one of the leading causes of death and disability, with a high incidence of over 11 million cases annually worldwide. Costs of treatment and rehabilitation, loss of work, and the hardships resulting from stroke are a major burden both at the individual and at the societal level. Importantly, stroke therapies need to be initiated early for them to be effective. Thrombolytic therapy and mechanical thrombectomy are early treatment options of ischemic stroke. In hemorrhagic stroke, optimization of hemodynamic and hemostatic parameters is central, and surgery is considered in a subset of patients. Efficient treatment of stroke requires early and precise recognition of stroke at all stages of the treatment chain. This includes identification of patients with suspected acute stroke by emergency medical dispatchers and emergency medical services staff, and precise admission diagnostics by the receiving on-call stroke team. Success requires grasping the complexity of stroke symptoms that depend on the brain areas affected, and the plethora of medical conditions that can mimic stroke. The Helsinki Ultra-acute Stroke Biomarker Study includes a cohort of 1015 patients transported to hospital due to suspected acute stroke, as candidates for revascularization therapies. Based on this cohort, this thesis work has explored new avenues to improve early stroke diagnostics in all stages of the treatment chain. In a detailed investigation into the identification of stroke by emergency medical dispatchers, we analyzed emergency phone calls with missed stroke identification. We also combined data on dispatch and EMS and hospital records to identify causes for missing stroke during emergency calls. Most importantly, we found that a patient’s fall at onset and patient confusion were strongly associated with missed identification. Regarding the Face Arm Speech Test (FAST), the most likely symptom to be misidentified was acute speech disturbance. Using prehospital blood sampling of stroke patients, and ultrasensitive measurement, we investigated the early dynamics of the plasma biomarkers glial fibrillary acidic protein (GFAP) and total tau. Utilizing serial sampling, we demonstrate for the first time that monitoring the early release rate of GFAP can improve the diagnostic performance of this biomarker for early differentiation between ischemic and hemorrhagic stroke. In our analysis of early GFAP levels, we were able to differentiate with high accuracy two-thirds of all patients with acute cerebral ischemia from those with hemorrhagic stroke, supporting further investigation of this biomarker as a promising point-of-care tool for prehospital stroke diagnostics. We performed a detailed review of the admission diagnostics of our cohort of 1015 patients to explore causes and predictors of admission misdiagnosis. We then investigated the consequences of misdiagnosis on outcomes. We demonstrate in this large cohort that the highly optimized and rapid admission evaluation in our hospital district (door-to-needle times below 20 minutes) did not compromise the accuracy and safety of admission evaluation. In addition, we discovered targets for improving future diagnostics. Finally, our detailed neuropathological investigation of a case of cerebral amyloid angiopathy (CAA) -related hemorrhage after stroke thrombolysis provided unique tissue-level evidence for this common vasculopathy as a notable risk factor for intracranial hemorrhagic complications in the setting of stroke. These findings support research to improve the diagnostics of CAA, and the prediction of hemorrhagic complications associated with stroke thrombolysis. In conclusion, these proposed targets and strategies will aid in the future improvement and development of this highly important field of diagnostics. Our proof-of-concept discoveries on early GFAP kinetics help guide further study into this diagnostic approach just as highly sensitive point-of-care GFAP measurement instruments are becoming available. Finally, our results support the safety of worldwide efforts to optimize emergency department door-to- needle times when care is taken to ensure sufficient expertise is in place, highlighting the role of the on-call vascular neurologist as a central diagnostic asset.Aivohalvaus on yksi yleisimpiĂ€ kuolinsyitĂ€ ja pitkĂ€kestoisen työkyvyttömyyden aiheuttajia. Aivohalvauksen aiheuttamat hoito- ja kuntoutuskustannukset, työkyvyn menetys ja arkielĂ€mĂ€n vaikeudet ovat mittava taakka sekĂ€ yksilön, lĂ€heisten ettĂ€ yhteiskunnan tasoilla. Tehokkaiden hoitojen vaatima nopeus edellyttÀÀ aivohalvauksen varhaista ja tarkkaa tunnistamista hoitoketjun kaikilla askelmilla. TĂ€ssĂ€ vĂ€itöskirjatyössĂ€ etsittiin uusia keinoja aivohalvauksen varhaisdiagnostiikan kehittĂ€miseksi hĂ€tĂ€keskuksessa, ensihoidossa ja vastaanottavan sairaalan HYKS:n pĂ€ivystyspoliklinikalla. Yksityiskohtainen analyysi aivohalvauksen tunnistamisesta hĂ€tĂ€keskuksessa osoitti, ettĂ€ potilaan kaatuminen ja sekavuus olivat puutteellisen tunnistamisen keskeisiĂ€ tekijöitĂ€. Face Arm Speech Test (FAST) -seulontaoireista puhehĂ€iriö oli todennĂ€köisimmin vÀÀrin tunnistettu. Akuuttivaiheen verinĂ€ytteitĂ€ ja ÀÀrimmĂ€isen herkkÀÀ mÀÀritysmenetelmÀÀ hyödyntĂ€en tutkimme kahden verestĂ€ mitattavan merkkiaineen, aivojen tukikudoksen tĂ€htisolujen sĂ€ikeisen happaman proteiinin (GFAP) ja taun varhaista dynamiikkaa aivohalvauspotilailla. Osoitimme ensimmĂ€istĂ€ kertaa, ettĂ€ GFAP:n varhaisen vapautumisnopeuden seurantaa sarjanĂ€ytteistĂ€ voidaan hyödyntÀÀ parantamaan tĂ€mĂ€n merkkiaineen erottelukykyĂ€ iskeemisen ja hemorragisen aivokudosvaurion varhaisdiagnostiikassa. Tulokset viittaavat siihen, että GFAP merkkiaine voisi olla jatkossa kehitettävissä ambulansseissa hyödynnettäväksi pikaverikokeeksi, joka auttaisi aivohalvauksen eri muotojen varhaisessa erottelussa. PĂ€ivystysdiagnostiikkaan keskittyvĂ€ssĂ€ osatyössĂ€ osoitimme ensimmĂ€istĂ€ kertaa suuressa aineistossa, ettĂ€ sairaanhoitopiirissĂ€mme vuosia optimoitu erittĂ€in nopea vastaanottoarviointi (liuotushoidon mediaaniviive alle 20 minuuttia sisĂ€ltĂ€en pÀÀn kuvauksen) ei vaaranna aivohalvauspotilaiden diagnostiikan tarkkuutta ja hoidon turvallisuutta. TĂ€ssĂ€ vĂ€itöskirjatyössĂ€ esitetyt kehityskohteet ja menetelmĂ€t auttavat tĂ€mĂ€n erittĂ€in tĂ€rkeĂ€n diagnostisen alan tulevassa kehitystyössĂ€. TyössĂ€ kuvatut tulokset sisĂ€ltĂ€vĂ€t uraauurtavia havaintoja verestĂ€ mitattavan GFAP merkkiaineen kinetiikan kĂ€ytöstĂ€ aivohalvauksen varhaisdiagnostiikassa ja tukevat sairaalapĂ€ivystysarvion diagnostista tarkkuutta HYKS:n tunnetusti erittĂ€in nopeassa liuotushoitoketjussa

    Intracranial Nimodipine Implant: Feasibility and Implications for the Treatment of Subarachnoid Hemorrhage – A Pre-Clinical Study

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    Intracranial aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition requiring immediate neurocritical care. A ruptured aneurysm must be isolated from arterial circulation to prevent rebleeding. Open surgical clipping of the neck of the aneurysm or intra-arterial filling of the aneurysm sack with platinum coils are major treatment strategies in an acute phase. About 40% of the patients suffering from aSAH die within a year of the bleeding despite the intensive treatment. After aSAH, the patient may develop a serious complication called vasospasm. Major risk for the vasospasm takes place at days 5–14 after the primary bleeding. In vasospasm, cerebral arteries contract uncontrollably causing brain ischemia that may lead to death. Nimodipine (NDP) is used to treat of vasospasm and it is administrated intravenously or orally every four hours for 21 days. NDP treatment has been scientifically proven to improve patients’ clinical outcome. The therapeutic effect of L-type calcium channel blocker NDP is due to the ability to dilate cerebral arteries. In addition to vasodilatation, recent research has shown the pleiotropic effect of NDP such as inhibition of neuronal apoptosis and inhibition of microthrombi formation. Indeed, NDP inhibits cortical spreading ischemia. Knowledge of the pathophysiology of the vasospasm has evolved in recent years to a complex entity of early brain injury, secondary injuries and cortical spreading ischemia, instead of being pure intracranial vessel spasm. High NDP levels are beneficial since they protect neurons and inhibit the cortical spreading ischemia. One of the drawbacks of the intravenous or oral administration of NPD is systemic hypotension, which is harmful particularly when the brain is injured. Maximizing the beneficial effects and avoiding systemic hypotension of NDP, we developed a sustained release biodegradable NDP implant that was surgically positioned in the basal cistern of animal models (dog and pig). Higher concentrations were achieved locally and lower concentrations systemically. Using this treatment approach in humans, it may be possible to reduce incidence of harmful hypotension and potentiate beneficial effects of NDP on neurons. Intracellular calcium regulation has a pivotal role in brain plasticity. NDP blocks L-type calcium channels in neurons, substantially decreasing intracellular calcium levels. Thus, we were interested in how NDP affects brain plasticity and tested the hypothesis in a mouse model. We found that NDP activates Brain-derived neurotrophic factor (BDNF) receptor TrkB and its downstream signaling in a reminiscent of antidepressant drugs. In contrast to antidepressant drugs, NDP activates Akt, a major survival-promoting factor. Our group’s previous findings demonstrate that long-term antidepressant treatment reactivates developmental-type of plasticity mechanisms in the adult brain, which allows the remodeling of neuronal networks if combined with appropriate rehabilitation. It seems that NDP has antidepressant-like properties and it is able to induce neuronal plasticity. In general, drug induced neuronal plasticity has a huge potential in neurorehabilitation and more studies are warranted.Siirretty Doriast
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