Major cardiovascular events in patients with cardiovascular monosodium urate deposits in atherosclerotic plaques.

OBJECTIVE: To determine the association of cardiovascular atherosclerotic plaque monosodium urate deposits with the occurrence of major cardiovascular events in gout and hyperuricemia patients. METHODS: This retrospective cohort study included patients with clinically suspicion of gout, who performed a dual energy computed tomography of the affected limb and thorax between June 1st, 2012 and December 5th, 2019. Clinical and laboratory parameters were retrieved from patients charts. Established cardiovascular risk factors were evaluated. Medical history review identified the presence of major adverse cardiac events with a median follow up time of 33 months (range 0-108 months) after the performed computed tomography scan. RESULTS: Full data sets were available for 189 patients: 131 (69.3%) gout patients, 40 (21.2%) hyperuricemia patients, and 18 (9.5%) controls. Patients with cardiovascular monosodium urate deposits (n = 85/189, 45%) revealed increased serum acute phase reactants, uric acid levels and calcium scores in computed tomography compared with patients without cardiovascular monosodium urate deposits. Major adverse cardiac events were observed in 35 patients (18.5%) with a higher prevalence in those patients revealing cardiovascular monosodium urate deposits (n = 22/85, 25.9%) compared with those without cardiovascular monosodium urate deposits (n = 13/104, 12.5%, OR 2.4, p= 0.018). CONCLUSION: This is the first study demonstrating the higher hazard of major adverse cardiac events in patients with dual energy computed tomography-verified cardiovascular monosodium urate deposits. The higher prevalence of cardiac events in patients with cardiovascular monosodium urate deposits may facilitate risk stratification of gout patients, as classical cardiovascular risk scores or laboratory markers fail in their proper identification.

CT analysis of the anterior nasal airway based on the direction of nasal airflow in patients with nasal obstruction and trauma controls.

PURPOSE: The anterior nose is the nasal segment with the highest resistance to airflow. In a hospital-based case-control study, we compared cross-sectional areas of the nasal cavities anterior to the piriform aperture determined by computed tomography (CT-CSA) in patients with nasal obstruction (cases) and unselected patients with trauma unrelated to the head and face (controls). METHODS: CT-CSA could be reproducibly identified at angles of 0o, 30°, 60°, and 90° to the nasal floor approximately perpendicular to the arcuate direction of nasal airflow using bony landmarks. CT-CSA were manually segmented and compared in cases and controls. In cases, we compared CT-CSA at 30° (CT-CSA30-narrow) with the minimum cross-sectional area determined by acoustic rhinometry (AR-MCA1-narrow), each on the narrower side. RESULTS: CT-CSA ranged from 7 to 250 mm2 with an average of 100 mm2 per nasal side. Side differences of the nasal airways indicating asymmetry of the nasal airways were greater in 40 cases than in 44 controls (p < 0.003). Moreover, bilateral CT-CSA were significantly smaller in cases than in controls (p < 0.001). CT-CSA30-narrow did not significantly correlate with AR-MCA1-narrow (r = 0.33; p = 0.07) and on average was 58% smaller than AR-MCA1-narrow. CONCLUSIONS: Cross-sectional areas of the anterior nose perpendicular to the direction of nasal airflow, which is considered relevant in terms of flow physics, can be reliably measured using CT. Anterior nasal cavities in patients with nasal obstruction were more asymmetric and, as a whole, narrower than in controls, the latter of which is not corrected by routine septoplasty.

Chest CT of Lung Injury 1 Year after COVID-19 Pneumonia: The CovILD Study.

Background The long-term pulmonary sequelae of COVID-19 is not well known. Purpose To characterize patterns and rates of improvement of chest CT abnormalities 1 year after COVID-19 pneumonia. Materials and Methods This was a secondary analysis of a prospective, multicenter observational cohort study conducted from April 29 to August 12, 2020, to assess pulmonary abnormalities at chest CT approximately 2, 3, and 6 months and 1 year after onset of COVID-19 symptoms. Pulmonary findings were graded for each lung lobe using a qualitative CT severity score (CTSS) ranging from 0 (normal) to 25 (all lobes involved). The association of demographic and clinical factors with CT abnormalities after 1 year was assessed with logistic regression. The rate of change of the CTSS at follow-up CT was investigated by using the Friedmann test. Results Of 142 enrolled participants, 91 underwent a 1-year follow-up CT examination and were included in the analysis (mean age, 59 years ± 13 [SD]; 35 women [38%]). In 49 of 91 (54%) participants, CT abnormalities were observed: 31 of 91 (34%) participants showed subtle subpleural reticulation, ground-glass opacities, or both, and 18 of 91 (20%) participants had extensive ground-glass opacities, reticulations, bronchial dilation, microcystic changes, or a combination thereof. At multivariable analysis, age of more than 60 years (odds ratio [OR], 5.8; 95% CI: 1.7, 24; P = .009), critical COVID-19 severity (OR, 29; 95% CI: 4.8, 280; P < .001), and male sex (OR, 8.9; 95% CI: 2.6, 36; P < .001) were associated with persistent CT abnormalities at 1-year follow-up. Reduction of CTSS was observed in participants at subsequent follow-up CT (P < .001); during the study period, 49% (69 of 142) of participants had complete resolution of CT abnormalities. Thirty-one of 49 (63%) participants with CT abnormalities showed no further improvement after 6 months. Conclusion Long-term CT abnormalities were common 1 year after COVID-19 pneumonia. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Leung in this issue.

A spark of hope: histopathological and functional recovery after critical COVID-19.

BACKGROUND: There are substantial concerns about fibrotic and vascular pulmonary sequelae after coronavirus disease 2019 (COVID-19) associated acute respiratory distress syndrome (ARDS).AQ1 Histopathology reports of lung biopsies from COVID-19 survivors are scarce. CASE: We herein report results of functional and histopathological studies in a 70 year-old man undergoing a co-incidental tumor lobectomy six months after long-term mechanical ventilation for COVID-19 pneumonia. CONCLUSION: Despite several unfavorable risk factors, this case presentation shows a completed pulmonary recovery process within a few months.

Technical efficacy and local recurrence after stereotactic radiofrequency ablation of 2653 liver tumors: a 15-year single-center experience with evaluation of prognostic factors.

PURPOSE: To assess the technical outcome and local tumor control of multi-probe stereotactic radiofrequency ablation (SRFA) in a large series of patients. Furthermore, to determine factors accounting for adverse outcomes. MATERIAL AND METHODS: Between 2003 and 2018, 865 patients were treated by SRFA for 2653 primary and metastatic liver tumors with a median tumor size of 2.0 cm (0.5 - 19 cm). Primary technical efficacy (PTE) and local recurrence (LR) were evaluated, and possible predictors for adverse events analyzed using uni- and multi-variable binary logistic regression. RESULTS: Overall, 2553 of 2653 tumors were successfully ablated at initial SRFA resulting in a PTE rate of 96.2%. Predictors of lower PTE rates were age > 70 years, tumor size > 5 cm, number of probes, location close to liver capsule/organs and segment II. LR occurred in 220 of 2653 tumors (8.3%) with the following predictors: age, tumor type/size, conglomerates, segments I/IVa/IVb, number of probes and location close to major vessels/bile duct. Multivariable analysis revealed tumor size > 5 cm (odds ratio [OR] 3.153), age > 70 years (OR 1.559), and location in segment II (OR 1.772) as independent prognostic factors for PTE, whereas tumor location close to major vessels (OR 1.653) and in segment IVb (OR 2.656) were identified as independent prognostic factors of LR. CONCLUSIONS: Stereotactic RFA is an attractive option in the management of primary or metastatic liver tumors with good local tumor control, even in large tumors. The presented prognostic factors for adverse local oncological outcome might help to stratify unfavorable tumors for ablation.

Cardiopulmonary recovery after COVID-19: an observational prospective multicentre trial.

BACKGROUND: After the 2002/2003 severe acute respiratory syndrome outbreak, 30% of survivors exhibited persisting structural pulmonary abnormalities. The long-term pulmonary sequelae of coronavirus disease 2019 (COVID-19) are yet unknown, and comprehensive clinical follow-up data are lacking. METHODS: In this prospective, multicentre, observational study, we systematically evaluated the cardiopulmonary damage in subjects recovering from COVID-19 at 60 and 100 days after confirmed diagnosis. We conducted a detailed questionnaire, clinical examination, laboratory testing, lung function analysis, echocardiography and thoracic low-dose computed tomography (CT). RESULTS: Data from 145 COVID-19 patients were evaluated, and 41% of all subjects exhibited persistent symptoms 100 days after COVID-19 onset, with dyspnoea being most frequent (36%). Accordingly, patients still displayed an impaired lung function, with a reduced diffusing capacity in 21% of the cohort being the most prominent finding. Cardiac impairment, including a reduced left ventricular function or signs of pulmonary hypertension, was only present in a minority of subjects. CT scans unveiled persisting lung pathologies in 63% of patients, mainly consisting of bilateral ground-glass opacities and/or reticulation in the lower lung lobes, without radiological signs of pulmonary fibrosis. Sequential follow-up evaluations at 60 and 100 days after COVID-19 onset demonstrated a vast improvement of symptoms and CT abnormalities over time. CONCLUSION: A relevant percentage of post-COVID-19 patients presented with persisting symptoms and lung function impairment along with radiological pulmonary abnormalities >100 days after the diagnosis of COVID-19. However, our results indicate a significant improvement in symptoms and cardiopulmonary status over time.

Dual-energy computed tomography in acute ischemic stroke: state-of-the-art.

Dual-energy computed tomography (DECT) allows distinguishing between tissues with similar X-ray attenuation but different atomic numbers. Recent studies demonstrated that this technique has several areas of application in patients with ischemic stroke and a potential impact on patient management. After endovascular stroke therapy (EST), hyperdense areas can represent either hemorrhage or contrast staining due to blood-brain barrier disruption, which can be differentiated reliably by DECT. Further applications are improved visualization of early infarctions, compared to single-energy computed tomography, and prediction of transformation into infarction or hemorrhage in contrast-enhancing areas. In addition, DECT allows detection and evaluation of the material composition of intra-arterial clots after EST. This review summarizes the clinical state-of-the-art of DECT in patients with stroke, and features some prospects for future developments. KEY POINTS: • Dual-energy computed tomography (DECT) allows differentiation between tissues with similar X-ray attenuation but differentatomic numbers. • DECT has several areas of application in patients with ischemic stroke and a potential impact on patient management. • Prospects for future developments in DECT may improve treatment decision-making.

Coronary atherosclerosis profile in patients with end-stage liver disease prior to liver transplantation due to alcoholic fatty liver: a coronary CTA study.

OBJECTIVES: To assess the coronary atherosclerosis profile by coronary computed tomography angiography (CTA) in patients with end-stage liver disease (ESLD) due to alcohol-related liver disease (ARLD) evaluated for liver transplantation (LT), in a retrospective matched case-controlled cohort study. METHODS: One hundred forty patients (age 60.6 years ± 9.8, 20.7% females) who underwent coronary CTA were included. Seventy patients with ESLD due to ARLD (ESLD-alc) were propensity score (1:1) matched for age, gender, and the major 5 cardiovascular risk factors with healthy controls. CTA analysis included the following: stenosis severity according to CAD-RADS as (0) = no, (1) minimal < 25%, (2) mild 25-50%, (3) moderate 50-70%, and (4) severe > 70% stenosis, total mixed plaque burden weighted for non-calcified component (G-score) and high-risk plaque criteria (Napkin-Ring, low attenuation plaque, spotty calcification, positive remodeling). RESULTS: Prevalence of coronary artery disease (CAD) was high (84.4%) in the ESLD-alc group but similar to controls. Stenosis severity was similar (CAD-RADS, 1.9 vs. 2.2, p = 0.289). High-grade stenosis (> 70%) was observed in 12.5% of ESLD-alc patients. High-risk plaques were less frequent in the ESLD-alc cohort as compared to controls (4.5% vs. 37.5%, p < 0.001), and total mixed plaque burden was lower (G-score, 4.9 versus 7.4, p = 0.001). Plaque density was lower in controls (56.6HU ± 3.2 vs. 91.3HU ± 4.5, p = 0.007) indicating more lipid-rich in controls, but higher mixed fibro-calcific plaque component in those with alcohol-related ESLD. CONCLUSION: Patients with alcohol-related ESLD exhibit more mixed fibro-calcified plaques but less plaque with high-risk features and less fibro-fatty plaque burden, while total CAD prevalence is high. KEY POINTS: • Patients with ESLD prior to LT have a high total prevalence of CAD and stenosis severity, which is similar to those of healthy controls with an identical cardiovascular risk profile. • Patients with ESLD prior to LT due to alcohol abuse have more calcific but less fibro-fatty plaque and less high-risk plaque. • CTA seems to be a useful imaging technique for risk stratification prior to LT.

Monosodium Urate Crystal Deposition in Coronary Artery Plaque by 128-Slice Dual-Energy Computed Tomography: An Ex Vivo Phantom and In Vivo Study.

OBJECTIVE: Monosodium uric acid (MSU) crystals may accumulate in the coronary plaque. The objective was to assess whether dual-energy computed tomography (DECT) allows for detection of MSU in coronary plaque. METHODS: Patients were examined with 128-slice DECT applying a cardiac electrocardiogram-gated and peripheral extremity protocol. Patients were divided into 3 groups: gout (tophi >1 cm in peripheral joints), hyperuricemia (>6.5 mg/dL serum uric acid), and controls. The groups were matched for cardiovascular risk factors. Monosodium uric acid-positive (+) and calcified plaque were distinguished, and the coronary artery calcium score was calculated. Ex vivo phantom: MSU solutions were diluted in different NaCL solutions (5%/10%/15%/20%/25%). Coronary artery models with 2 different plaque types (MSU+ and calcified) were created. RESULTS: A total of 96 patients were included (37 with gout, 33 with hyperuricemia, and 26 controls). Monosodium uric acid-positive plaques were found more often in patients with gout as compared with controls (91.9% vs 0.38%; P < 0.0001), and the number of plaques was higher (P < 0.0001). Of 102 MSU+ plaques, 26.7% were only MSU+ and 74.2% were mixed MSU+/calcified. Monosodium uric acid-positive plaque had mean 232.3 Hounsfield units (range, 213-264). Coronary artery calcium score was higher in patients with gout as compared with controls (659.1 vs 112.4 Agatston score; P < 0.001). Patients with gout had more MSU+ plaques as compared with patients with hyperuricemia (91.6% vs 2.9%; P < 0.0001), and coronary artery calcium score was higher (659.1 vs 254 Agatston score; P < 0.001), but there was no difference between patients with hyperuricemia and controls. Ex vivo phantom study: MSU crystals were detected by DECT in solutions with a concentration of 15% or greater MSU and could be distinguished from calcified. CONCLUSIONS: Coronary MSU+ plaques can be detected by DECT in patients with gout.

Persisting alterations of iron homeostasis in COVID-19 are associated with non-resolving lung pathologies and poor patients' performance: a prospective observational cohort study.

BACKGROUND: Severe coronavirus disease 2019 (COVID-19) is frequently associated with hyperinflammation and hyperferritinemia. The latter is related to increased mortality in COVID-19. Still, it is not clear if iron dysmetabolism is mechanistically linked to COVID-19 pathobiology. METHODS: We herein present data from the ongoing prospective, multicentre, observational CovILD cohort study (ClinicalTrials.gov number, NCT04416100), which systematically follows up patients after COVID-19. 109 participants were evaluated 60 days after onset of first COVID-19 symptoms including clinical examination, chest computed tomography and laboratory testing. RESULTS: We investigated subjects with mild to critical COVID-19, of which the majority received hospital treatment. 60 days after disease onset, 30% of subjects still presented with iron deficiency and 9% had anemia, mostly categorized as anemia of inflammation. Anemic patients had increased levels of inflammation markers such as interleukin-6 and C-reactive protein and survived a more severe course of COVID-19. Hyperferritinemia was still present in 38% of all individuals and was more frequent in subjects with preceding severe or critical COVID-19. Analysis of the mRNA expression of peripheral blood mononuclear cells demonstrated a correlation of increased ferritin and cytokine mRNA expression in these patients. Finally, persisting hyperferritinemia was significantly associated with severe lung pathologies in computed tomography scans and a decreased performance status as compared to patients without hyperferritinemia. DISCUSSION: Alterations of iron homeostasis can persist for at least two months after the onset of COVID-19 and are closely associated with non-resolving lung pathologies and impaired physical performance. Determination of serum iron parameters may thus be a easy to access measure to monitor the resolution of COVID-19. TRIAL REGISTRATION: ClinicalTrials.gov number: NCT04416100.

Nasal Floor Asymmetry Is Associated With Nasal Obstruction.

PURPOSE: The role of morphologic characteristics of the nasal cavity in nasal obstruction is not yet sufficiently understood. The aim of this study was to determine which morphometric parameters of the nasal cavity severely impair nasal breathing and when. PATIENTS AND METHODS: In a hospital-based, computed tomography-morphometric cross-sectional study, we evaluated computed tomography coronal scans of patients with known nasal obstruction scheduled to undergo functional nasal surgical procedures (cases) and trauma patients without facial involvement or known nasal obstruction (controls). The primary predictor variable was case versus control. In both groups, we measured and compared the piriform aperture width; nasal floor canting; piriform aperture vertical height, height-width ratio, and total cross-sectional area; height difference between the right and left nasal floors; and nasal septal thickness; as well as age and gender differences. Metric data means, standard deviations, and 95% confidence intervals were calculated and analyzed. RESULTS: The sample was composed of 60 patients evenly divided between cases and controls. Of these, 30 were men. The average age of the cases and controls was 27.4 ± 7.8 years and 38.5 ± 18.6 years, respectively (P < .001). The differences in piriform aperture width were not statistically significant between cases and controls (23.3 ± 1.9 mm and 23.8 ± 1.7 mm, respectively; P > .2). In contrast, we noted statistically significant differences between cases and controls in nasal floor canting (5.4° ± 4.6° and 1.8° ± 1.5°, respectively; P < .001) and height difference between the right and left nasal floors (1.8 ± 1.2 mm and 1.0 ± 0.7 mm, respectively; P = .002). CONCLUSIONS: Nasal floor canting of 3° or greater and a height difference between the right and left nasal floors of 1.5 mm or greater may contribute to the etiology of clinically relevant nasal obstruction. A piriform aperture width of 22 mm or less may be considered narrow. Future studies can determine when and how exactly to surgically address a clinically relevant narrow piriform aperture and nasal floor canting.

[Traumatic aortic rupture - diagnosis and managment]. / Die traumatische Aortenruptur.

Road traffic accidents are the main cause of traumatic aortic ruptures, mostly in combination with other severe injuries. The pre-hospital mortality rate is high. Suspected aortic trauma, following a high traumatic aortic injury score, is an indication for computer tomography. Injuries are triaged and the treatment priority of the aortic trauma is ascertained based on the severity of the aortic and concomitant injuries and the condition of the patient. Until definitive treatment of the aortic lesion is completed, the blood pressure of the patient must be kept low. Grade I and II lesions can be managed under strict monitoring with initial conservative treatment in individual cases. Grade III (contained perforation) and grade IV (open rupture) lesions need surgical or interventional treatment as swiftly as possible. In selected cases, a delayed treatment can also be advantageous.The endovascular stent graft therapy has established itself as the preferred form of treatment.

Systemic Hypotension Following Intravenous Administration of Nonionic Contrast Medium During Computed Tomography: Iopromide Versus Iodixanol.

BACKGROUND: In light of the increasing number of radiologic interventions performed under general anesthesia, the effects of contrast media (CM) on circulation and organ perfusion are of paramount importance. The objectives of this study were to systematically quantify effects on blood pressure, heart rate, and kidney function following intravenous administration of nonionic CM with normal and low osmolality. METHODS: In this controlled, double-blinded phase IV clinical trial, 40 consecutive patients were randomly assigned to receive repeated measures of either low-osmolar iopromide or iso-osmolar iodixanol. Normal saline solution (NSS) served as control. Blood pressure and heart rate were measured continuously from 1 minute before until 3 minutes after administration of CM and NSS. Urine output was recorded hourly. RESULTS: Administration of iopromide resulted in systemic hypotension lasting up to 300 seconds (105 ± 61 seconds) with the lowest mean arterial pressure of 39 mm Hg (56.7 ± 12.2 mm Hg). Iopromide caused a systolic/diastolic decrease of 31/26 mm Hg (P < .001), significant increase in heart rate (P = .042), and significant diuresis with a 2-fold higher per-hour urine output (P = .010). Administration of iodixanol and NSS had no significant influence on blood pressure (P > .640). CONCLUSIONS: Administration of low-osmolar iopromide was followed by a significant transient decrease in blood pressure and a rise in heart rate. Anesthetists and radiologists should be aware of these effects in patients in whom short episodes of disturbed tissue microcirculation may pose a clinical risk.

[Head & Neck MRI: What ENT specialists should know]. / Kopf-Hals-MRT: Was HNO-Ärzte wissen sollten.

Magnetic resonance imaging (MRI) has become an important imaging technique for otorhinolaryngology. The aim of the present CME contribution for ENT physicians is to provide an overview of the advantages and disadvantages as well as the possibilities of head and neck MRI and to summarize the main clinical applications of the various MRI sequences. Basic sequences (T1w, T2w, T1wC+) and fat suppression sequences (TIRM/STIR, Dixon, Spectral Fat sat) are the basis for evaluating inflammation, congenital lesions and tumors. High-resolution 3D sequences - SSFP (CISS, FIESTA), SPACE, VISTA, 3D-FLAIR - are used to assess the cranial nerves, labyrinth, and endolymphatic hydrops in Morbus Menière. Vascular sequences (3D-TOF, TWIST/TRICKS) are used in vascular contact syndromes and vascular malformations. Diffusion sequences (EPI-DWI, non-EPI-DWI, RESOLVE) are used for the evaluation of cholesteatoma, assessment of malignancy and evaluation of response to radio (chemo) therapy.

Effect of ultra-low doses, ASIR and MBIR on density and noise levels of MDCT images of dental implant sites.

OBJECTIVES: Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. METHODS: Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. RESULTS: Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). CONCLUSIONS: Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. KEY POINTS: • Ultra-low-dose MDCT protocols allowed more than 90 % reductions in dose. • Decreasing the dose generally increased density and noise. • Effect of IRT on density and noise varies with reconstruction kernel. • Accuracy of low-dose protocols for interpretation of bony anatomy not known. • Effect of low doses on accuracy of computer-aided design models unknown.

Open surgical retrieval of an embolized PFO occluder system.

Device migration after intervention for persistent foramen ovale occlusion is a rare complication. In case of failure of endovascular device retrieval, open surgical removal is indicated, safe, and reliable.

Ultralow-dose CT of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction and model-based iterative reconstruction: 2D and 3D image quality.

OBJECTIVE. The purpose of this article is to evaluate 2D and 3D image quality of high-resolution ultralow-dose CT images of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) in comparison with standard filtered backprojection (FBP). MATERIALS AND METHODS. A formalin-fixed human cadaver head was scanned using a clinical reference protocol at a CT dose index volume of 30.48 mGy and a series of five ultralow-dose protocols at 3.48, 2.19, 0.82, 0.44, and 0.22 mGy using FBP and ASIR at 50% (ASIR-50), ASIR at 100% (ASIR-100), and MBIR. Blinded 2D axial and 3D volume-rendered images were compared with each other by three readers using top-down scoring. Scores were analyzed per protocol or dose and reconstruction. All images were compared with the FBP reference at 30.48 mGy. A nonparametric Mann-Whitney U test was used. Statistical significance was set at p < 0.05. RESULTS. For 2D images, the FBP reference at 30.48 mGy did not statistically significantly differ from ASIR-100 at 3.48 mGy, ASIR-100 at 2.19 mGy, and MBIR at 0.82 mGy. MBIR at 2.19 and 3.48 mGy scored statistically significantly better than the FBP reference (p = 0.032 and 0.001, respectively). For 3D images, the FBP reference at 30.48 mGy did not statistically significantly differ from all reconstructions at 3.48 mGy; FBP and ASIR-100 at 2.19 mGy; FBP, ASIR-100, and MBIR at 0.82 mGy; MBIR at 0.44 mGy; and MBIR at 0.22 mGy. CONCLUSION. MBIR (2D and 3D) and ASIR-100 (2D) may significantly improve subjective image quality of ultralow-dose images and may allow more than 90% dose reductions.

Different techniques of static/dynamic guided implant surgery: modalities and indications.

For computer-guided surgery a static surgical guide is used that transfers the virtual implant position from computerized tomographic data to the surgical site. These guides are produced by computer-aided design/computer-assisted manufacture technology, such as stereolithography, or manually in a dental laboratory (using mechanical positioning devices or drilling machines). With computer-navigated surgery the position of the instruments in the surgical area is constantly displayed on a screen with a three-dimensional image of the patient. In this way, the system allows real-time transfer of the preoperative planning and visual feedback on the screen. A workflow of the different systems is presented in this review.