Browsing by Subject "COMPUTED-TOMOGRAPHY"

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  • Luoto, Teemu M.; Raj, Rahul; Posti, Jussi P.; Gardner, Andrew J.; Panenka, William J.; Iverson, Grant L. (2017)
    Background: The extensive use of computed tomography (CT) after acute head injury is costly and carries potential iatrogenic risk. This systematic review examined the usefulness of blood-based glial fibrillary acidic protein (GFAP) for predicting acute trauma-related CT-positive intracranial lesions following head trauma. The main objective was to summarize the current evidence on blood-based GFAP as a potential screening test for acute CT-positive intracranial lesions following head trauma. Methods: We screened MEDLINE, EMBASE, Psychlnfo, CINAHL, Web of Science, the Cochrane Database, Scopus, Clinical Trials, OpenGrey, ResearchGate, and the reference lists of eligible publications for original contributions published between January 1980 and January 2017. Eligibility criteria included: (i) population: human head and brain injuries of all severities and ages; (ii) intervention: blood -based GFAP measurement Results: The initial search identified 4,706 articles, with 51 eligible for subsequent full-text assessment. Twenty-seven articles were ultimately included. Twenty-four (89%) studies reported a positive association between GFAP level and acute trauma-related intracranial lesions on head CT. The area under the receiver operating characteristic curve for GFAP prediction of intracranial pathology ranged from 0.74 to 0.98 indicating good to excellent discrimination. GFAP seemed to discriminate mass lesions and diffuse injury, with mass lesions having significantly higher GFAP levels. There was considerable variability between the measured GFAP averages between studies and assays. No well-designed diagnostic studies with specific GFAP cutoff values predictive of acute traumatic intracranial lesions have been published. Conclusion: Intracranial CT-positive trauma lesions were associated with elevated GFAP levels in the majority of studies. Methodological heterogeneity in GFAP assessments and the lack of well-designed diagnostic studies with commercially validated GFAP platforms hinder the level of evidence, and variability in levels of GFAP with no clearly established cutoff for abnormality limit the clinical usefulness of the biomarker. However, blood based GFAP holds promise as a means of screening for acute traumatic CT-positive lesion following head trauma.
  • Pyorala, Jiri; Kankare, Ville; Liang, Xinlian; Saarinen, Ninni; Rikala, Juha; Kivinen, Veli-Pekka; Sipi, Marketta; Holopainen, Markus; Hyyppa, Juha; Vastaranta, Mikko (2019)
    Wood procurement in sawmills could be improved by resolving detailed three-dimensional stem geometry references from standing timber. This could be achieved, using the increasingly available terrestrial point clouds from various sources. Here, we collected terrestrial laser-scanning (TLS) data from 52 Scots pines (Pinus sylvestris L.) with the purpose of evaluating the accuracy of the log geometry and analysing its relationship with wood quality. For reference, the log-specific top-end diameter, volume, tapering, sweep, basic density and knottiness were measured in a sawmill. We produced stem models from the TLS data and bucked them into logs similar to those measured in the sawmill. In comparison to the sawmill data, the log-specific TLS-based top-end diameter, volume, taper and sweep estimates showed relative mean differences of 1.6, -2.4, -3.0 and 78 per cent, respectively. The correlation coefficients between increasing taper and decreasing wood density and whorl-to-whorl distances were 0.49 and -0.51, respectively. Although the stem-model geometry was resolved from the point clouds with similar accuracy to that at the sawmills, the remaining uncertainty in defining the sweep and linking the wood quality with stem geometry may currently limit the method's feasibilities. Instead of static TLS, mobile platforms would likely be more suitable for operational point cloud data acquisition.
  • Takatalo, Jani; Karppinen, Jaro; Taimela, Simo; Niinimaki, Jaakko; Laitinen, Jaana; Sequeiros, Roberto Blanco; Samartzis, Dino; Korpelainen, Raija; Nayha, Simo; Remes, Jouko; Tervonen, Osmo (2013)
  • Kaimio, Mirja L. M.; Lappalainen, Anu K.; Rahmani, Vahideh; Männikkö, Sofia; Laitinen-Vapaavuori, Outi M. (2020)
    Otitis externa and otitis media are common in American Cocker Spaniels, however breed-specific aural CT descriptions are currently lacking. This prospective and retrospective, observational, analytical study aimed to describe quantitative CT characteristics of the horizontal ear canal and the tympanic bulla in American Cocker Spaniels versus similar-sized mesaticephalic dogs. We prospectively performed clinical examinations and aural CT scanning for 38 American Cocker Spaniels. Computed tomographic transverse area of the osseous horizontal ear canal (TA1), transverse area of the widest air-filled part of the cartilaginous horizontal ear canal (TA2), tympanic bulla volume, and tympanic bulla wall thickness were measured. The TA1 and TA2 measurements were compared with those of 23 retrospectively recruited, similar-sized mesaticephalic dogs that had undergone CT-scanning of the head for non-ear-related reasons. The TA1 and TA2 did not differ for healthy American Cocker Spaniels and mesaticephalic dogs. Severely affected American Cocker Spaniels had significantly smaller TA2 (P <.001). The intraclass correlation coefficient for intraobserver and interobserver repeatability was 0.972 and 0.983 for TA1 and 0.994 and 0.998 for TA2, respectively. Variation between individuals was subjectively noted in healthy and affected American Cocker Spaniels, but mean tympanic bulla volume was slightly smaller in relation to body weight, and the tympanic bulla wall was thicker than in previous reports for mesaticephalic dogs. The tympanic bulla wall appeared thicker rostro-ventrally than caudo-ventrally in 44% of the dogs. Our results imply that a relatively thick tympanic bulla wall may be a normal CT variation and should be interpreted cautiously in this breed.
  • Saarikko, Anne; Mellanen, Eero; Kuusela, Linda; Leikola, Junnu; Karppinen, Atte; Autti, Taina; Virtanen, Pekka; Brandstack, Nina (2020)
    Summary Purpose Black Bone (BB) magnetic resonance imaging (MRI) is a nonionizing imaging method and a recent alternative to computed tomography (CT) in the examination of cranial deformities. The purpose of this study was to compare BB-MRI and routine 3D-CT in the preoperative evaluation of patients with craniosynostosis. Methods At our center, we have routinely performed preoperative CT of the skull and brain MRI for patients with clinical suspicion of craniosynostosis. We recently changed our MRI protocol into one that includes sequences for the evaluation of both brain anatomy and skull bone and sutures by BB-MRI. A semi-automatic skull segmentation algorithm was developed to facilitate visualization. Both BB-MRI and 3D-CT were performed on 9 patients with clinical craniosynostosis, and the images were evaluated by two craniofacial surgeons, one pediatric neurosurgeon, and two neuroradiologists. Results We obtained informative 3D images using BB-MRI. Six (6/9) patients had scaphocephaly, 1 (1/9) patient had unicoronal synostosis, and 2 (2/9) patients had lambdoid synostosis. The affected synostotic sutures could be identified both by BB-MRI and by 3D-CT in all patients. Intra-rater and inter-rater reliability for rating the calvarial sutures was high. However, the reliability for rating the intracranial impressions was low by both imaging methods. Conclusion BB-MRI is an alternative to 3D-CT in the preoperative evaluation of patients with craniosynostosis. BB-MRI provides information not only on cranial sutures and intracranial impressions but also on the brain structure in one imaging session. This method can replace ionizing radiation-based methods in analyzing skull deformities.
  • Petäjä, Elina M.; Yki-Järvinen, Hannele (2016)
    Non-alcoholic fatty liver disease (NAFLD) covers a spectrum of disease ranging from simple steatosis (NAFL) to non-alcoholic steatohepatitis (NASH) and fibrosis. "Obese/Metabolic NAFLD" is closely associated with obesity and insulin resistance and therefore predisposes to type 2 diabetes and cardiovascular disease. NAFLD can also be caused by common genetic variants, the patatin-like phospholipase domain-containing 3 (PNPLA3) or the transmembrane 6 superfamily member 2 (TM6SF2). Since NAFL, irrespective of its cause, can progress to NASH and liver fibrosis, its definition is of interest. We reviewed the literature to identify data on definition of normal liver fat using liver histology and different imaging tools, and analyzed whether NAFLD caused by the gene variants is associated with insulin resistance. Histologically, normal liver fat content in liver biopsies is most commonly defined as macroscopic steatosis in less than 5% of hepatocytes. In the population-based Dallas Heart Study, the upper 95th percentile of liver fat measured by proton magnetic spectroscopy (1H-MRS) in healthy subjects was 5.6%, which corresponds to approximately 15% histological liver fat. When measured by magnetic resonance imaging (MRI)-based techniques such as the proton density fat fraction (PDFF), 5% macroscopic steatosis corresponds to a PDFF of 6% to 6.4%. In contrast to "Obese/metabolic NAFLD", NAFLD caused by genetic variants is not associated with insulin resistance. This implies that NAFLD is heterogeneous and that "Obese/Metabolic NAFLD" but not NAFLD due to the PNPLA3 or TM6SF2 genetic variants predisposes to type 2 diabetes and cardiovascular disease.
  • Kaasalainen, Touko; Ekholm, Marja; Siiskonen, Teemu; Kortesniemi, Mika (2021)
    Cone beam computed tomography (CBCT) is a diverse 3D x-ray imaging technique that has gained significant popularity in dental radiology in the last two decades. CBCT overcomes the limitations of traditional twodimensional dental imaging and enables accurate depiction of multiplanar details of maxillofacial bony structures and surrounding soft tissues. In this review article, we provide an updated status on dental CBCT imaging and summarise the technical features of currently used CBCT scanner models, extending to recent developments in scanner technology, clinical aspects, and regulatory perspectives on dose optimisation, dosimetry, and diagnostic reference levels. We also consider the outlook of potential techniques along with issues that should be resolved in providing clinically more effective CBCT examinations that are optimised for the benefit of the patient.
  • Rytkönen, Kaisa; Ventä, Irja (2018)
    The aim of the study was to evaluate the proximity of the mandibular third molar (M3) and the inferior alveolar canal (IAC) in a panoramic radiograph of 20-year-old subjects. The specific aim was to assess differences in this proximity over time. Two similar samples of panoramic radiographs taken in a routine oral health examination with 20-year time interval were examined retrospectively and images with both mandibular M3s were included. The material consisted of 300 subjects (25% men, mean age 20.5 +/- 0.6 years). The radiographic relationship between the mandibular M3 root and the IAC was assessed as follows: the M3 root was either apart from, tangential to, superimposed with, or inferior to the IAC. Differences between frequencies were tested using the chi-squared test. In the combined samples, only 16% of the M3s located apart from the IAC, 15% located tangential to, 61% superimposed with, and 8% inferior to the IAC. The proportion of the intimate locations had increased during the 20-year time interval from 79 to 88% (P <0.01) and especially in females (P <0.05). The vast majority of the mandibular M3s situated very close to the mandibular canal. Our results suggest that in the cohort of 20-year-old non-extraction subjects, most of the M3s are possibly at risk for inferior alveolar nerve injury at removal, as judged from the panoramic radiograph, and also the number of such teeth has increased over the 20-year period.
  • Snäll, Johanna; Narjus-Sterba, M.; Toivari, M.; Wilkman, T.; Thoren, H. (2019)
    PurposeThe aim of this study was to investigate the relationship between intraorbital volume change caused by orbital fracture and globe malposition (GMP) in blow-out fracture patients undergoing surgery and to clarify the significance of different radiologically detected predictors associated with GMP.Patients and methodsA 6-month prospective follow-up study of unilateral isolated orbital fractures was designed and implemented. The main outcome variable was GMP (present or absent); the secondary outcome was orientation of GMP (horizontal or vertical). The primary predictor variable was postoperative orbital volume difference determined as the difference between the fractured and non-fractured orbit (measured in milliliter and analyzed in milliliter and percentages). The explanatory variables were gender, age, treatment delay from trauma to surgery, fracture site, horizontal depth of the fracture, fracture area, maximum vertical dislocation of the fracture, and preoperative volume difference.ResultsA total of 15 patients fulfilled the inclusion criteria and were followed for 6months from a larger cohort. GMP was detected in 6/15 patients (40.0%). GMP was more often present in large (2.5cm(2)) fractures (55.6%), in combined orbital fractures (50.0%), and in fractures with preoperative volume difference 2.5ml (62.5%) regardless of the postoperative volume correction. Postoperatively, patients with and without GMP displayed overcorrection of orbital volume; 4.15% corresponded to 1.15ml (with GMP) and 7.6% corresponded to 1.9ml (without GMP).ConclusionGMP was present in large and combined orbital fractures. Clinically detectable postoperative GMP occurred despite satisfactory orbital reconstruction and overcorrection. Mild GMP, however, is not significant for the patient.
  • Koivisto, Juha; Kiljunen, Timo; Kadesjo, Nils; Shi, Xie-Qi; Wolff, Jan (2015)
  • Hokkinen, Lasse M I; Mäkelä, Teemu Olavi; Savolainen, Sauli; Kangasniemi, Marko Matti (2021)
    Background Computed tomography angiography (CTA) imaging is needed in current guideline-based stroke diagnosis, and infarct core size is one factor in guiding treatment decisions. We studied the efficacy of a convolutional neural network (CNN) in final infarct volume prediction from CTA and compared the results to a CT perfusion (CTP)-based commercially available software (RAPID, iSchemaView). Methods We retrospectively selected 83 consecutive stroke cases treated with thrombolytic therapy or receiving supportive care that presented to Helsinki University Hospital between January 2018 and July 2019. We compared CNN-derived ischaemic lesion volumes to final infarct volumes that were manually segmented from follow-up CT and to CTP-RAPID ischaemic core volumes. Results An overall correlation of r = 0.83 was found between CNN outputs and final infarct volumes. The strongest correlation was found in a subgroup of patients that presented more than 9 h of symptom onset (r = 0.90). A good correlation was found between the CNN outputs and CTP-RAPID ischaemic core volumes (r = 0.89) and the CNN was able to classify patients for thrombolytic therapy or supportive care with a 1.00 sensitivity and 0.94 specificity. Conclusions A CTA-based CNN software can provide good infarct core volume estimates as observed in follow-up imaging studies. CNN-derived infarct volumes had a good correlation to CTP-RAPID ischaemic core volumes.
  • Raj, Rahul; Siironen, Jari; Kivisaari, Riku; Kuisma, Markku; Brinck, Tuomas; Lappalainen, Jaakko; Skrifvars, Markus B. (2013)
  • Kelaranta, A.; Mäkelä, T.; Kaasalainen, T.; Kortesniemi, M. (2017)
    Purpose: To determine fetal doses in different stages of pregnancy in three common computed tomography (CT) examinations: pulmonary CT angiography, abdomino-pelvic and trauma scan with Monte Carlo (MC) simulations. Methods: An adult female anthropomorphic phantom was scanned with a 64-slice CT using pulmonary angiography, abdomino-pelvic and trauma CT scan protocols. Three different sized gelatin boluses placed on the phantom's abdomen simulated different stages of pregnancy. Intrauterine dose was used as a surrogate to a dose absorbed to the fetus. MC simulations were performed to estimate uterine doses. The simulation dose levels were calibrated with volumetric CT dose index (CTDIvol) measurements and MC simulations in a cylindrical CTDI body phantom and compared with ten point doses measured with metal-oxide-semiconductor field-effect-transistor dosimeters. Intrauterine volumes and uterine walls were segmented and the respective dose volume histograms were calculated. Results: The mean intrauterine doses in different stages of pregnancy varied from 0.04 to 1.04 mGy, from 4.8 to 5.8 mGy, and from 9.8 to 12.6 mGy in the CT scans for pulmonary angiography, abdomino-pelvic and trauma CT scans, respectively. MC simulations showed good correlation with the MOSFET measurement at the measured locations. Conclusions: The three studied examinations provided highly varying fetal doses increasing from sub-mGy level in pulmonary CT angiography to notably higher levels in abdomino-pelvic and trauma scans where the fetus is in the primary exposure range. Volumetric dose distribution offered by MC simulations in an appropriate anthropomorphic phantom provides a comprehensive dose assessment when applied in adjunct to point-dose measurements.
  • Bayat, Sam; Porra, Liisa; Suortti, Pekka; Thomlinson, William (2020)
    Many lung disease processes are characterized by structural and functional heterogeneity that is not directly appreciable with traditional physiological measurements. Experimental methods and lung function modeling to study regional lung function are crucial for better understanding of disease mechanisms and for targeting treatment. Synchrotron radiation offers useful properties to this end: coherence, utilized in phase-contrast imaging, and high flux and a wide energy spectrum which allow the selection of very narrow energy bands of radiation, thus allowing imaging at very specific energies. K-edge subtraction imaging (KES) has thus been developed at synchrotrons for both human and small animal imaging. The unique properties of synchrotron radiation extend X-ray computed tomography (CT) capabilities to quantitatively assess lung morphology, and also to map regional lung ventilation, perfusion, inflammation and biomechanical properties, with microscopic spatial resolution. Four-dimensional imaging, allows the investigation of the dynamics of regional lung functional parameters simultaneously with structural deformation of the lung as a function of time. This review summarizes synchrotron radiation imaging methods and overviews examples of its application in the study of disease mechanisms in preclinical animal models, as well as the potential for clinical translation both through the knowledge gained using these techniques and transfer of imaging technology to laboratory X-ray sources.
  • Kelaranta, A.; Toroi, P.; Vock, P. (2016)
    Purpose: Converting the measurable quantities to patient organ doses in projection radiography is usually based on a standard-sized patient model and a specific radiation quality, which are likely to differ from the real situation. Large inaccuracies can therefore be obtained in organ doses, because organ doses are dependent on the exposure parameters, exposure geometry and patient anatomy. In this study, the effect of radiation quality and patient thickness on the organ dose conversion factors were determined. Methods: In this study, the posterior-anterior projection radiograph of the thorax was selected in order to determine the effect of radiation quality (tube voltages of 70-130 kV and total filtrations of 3 mmAl to 4 mmAl + 0.2 mmCu) and patient thickness (anterior-posterior thicknesses of 19.4-30.8 cm) on the breast and lung dose conversion factors. For this purpose, Monte Carlo simulation programs ImpactMC and PCXMC were used with computed tomography examination data of adult male and female patients and mathematical hermaphrodite phantoms, respectively. Results: Compared to the reference beam quality and patient thickness, the relative variation range in organ dose conversion factors was up to 74% for different radiation qualities and 122% for different patient thicknesses. Conclusions: Conversion factors should only be used with comprehensive understanding of the exposure conditions, considering the exposure parameters, exposure geometry and patient anatomy they are valid for. This study demonstrates that patient thickness-specific and radiation quality-specific conversion factors are needed in projection radiography. (C) 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
  • Piirainen, Kirsi Johanna; Viitanen, Sanna Johanna; Lappalainen, Anu Katriina; Mölsä, Sari Helena (2018)
    Background: Tracheal tumors are rarely diagnosed in veterinary medicine and the majority of tracheal neoplasia reported in adult dogs are malignant. Intratracheal lipoma has not been previously reported in the veterinary literature. Case presentation: A 7-year-old Briard dog was evaluated for inspiratory dyspnoea and an inspiratory wheeze. Cervical radiographs and tracheoscopic examination revealed an intratracheal mass that was surgically removed. The dog has been asymptomatic after the surgery. Conclusions: Based on histopathology, the mass was diagnosed as lipoma. To the authors' knowledge, this is the first published report of an intratracheal lipoma in the veterinary literature.
  • Toivanen, Jussi; Meaney, Alexander; Siltanen, Samuli; Kolehmainen, Ville (2020)
    Multi-energy CT takes advantage of the non-linearly varying attenuation properties of elemental media with respect to energy, enabling more precise material identification than single-energy CT. The increased precision comes with the cost of a higher radiation dose. A straightforward way to lower the dose is to reduce the number of projections per energy, but this makes tomographic reconstruction more ill-posed. In this paper, we propose how this problem can be overcome with a combination of a regularization method that promotes structural similarity between images at different energies and a suitably selected low-dose data acquisition protocol using non-overlapping projections. The performance of various joint regularization models is assessed with both simulated and experimental data, using the novel low-dose data acquisition protocol. Three of the models are well-established, namely the joint total variation, the linear parallel level sets and the spectral smoothness promoting regularization models. Furthermore, one new joint regularization model is introduced for multi-energy CT: a regularization based on the structure function from the structural similarity index. The findings show that joint regularization outperforms individual channel-by-channel reconstruction. Furthermore, the proposed combination of joint reconstruction and non-overlapping projection geometry enables significant reduction of radiation dose.
  • WSES-AAST Expert Panel; Coccolini, Federico; Moore, Ernest E.; Kluger, Yoram; Leppäniemi, Ari; Catena, Fausto (2019)
    Renal and urogenital injuries occur in approximately 10-20% of abdominal trauma in adults and children. Optimal management should take into consideration the anatomic injury, the hemodynamic status, and the associated injuries. The management of urogenital trauma aims to restore homeostasis and normal physiology especially in pediatric patients where non-operative management is considered the gold standard. As with all traumatic conditions, the management of urogenital trauma should be multidisciplinary including urologists, interventional radiologists, and trauma surgeons, as well as emergency and ICU physicians. The aim of this paper is to present the World Society of Emergency Surgery (WSES) and the American Association for the Surgery of Trauma (AAST) kidney and urogenital trauma management guidelines.