PURPOSE: This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. MATERIALS AND METHODS: A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo T1-weighted images, fast spin-echo T2-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. RESULTS: Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. CONCLUSION: With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.
Artifacts* ; Bicuspid ; Magnetic Resonance Imaging* ; Mandible ; Nickel ; Orthodontic Brackets* ; Orthodontic Wires ; Stainless Steel ; Titanium

BACKGROUND: Due to the tropism of human parvovirus B19 to erythroid progenitor cells, infection in patients with an underlying hemolytic disorder such as beta-thalassemia major leads to suppression of erythrocyte formation, referred to as transient aplasia crisis (TAC), which may be life-threatening. We investigated the prevalence of parvovirus B19 among patients with beta thalassemia major attending the Zafar Adult Thalassemia Clinic in Tehran, Iran. METHODS: This cross-sectional study was performed to determine the presence of parvovirus B19 DNA in blood samples and parvovirus B19 genotypes in plasma samples of patients with thalassemia major. The population consisted of 150 patients with beta-thalassemia major who attended the Zafar clinic in Tehran. Specimens were studied using a real-time polymerase chain reaction assay. RESULTS: The prevalence of parvovirus B19 in our study population was 4%. Of 150 patients with thalassemia, six (4%) were positive for B19 DNA. There was no significant correlation between blood transfusion frequency and B19 DNA positivity. Finally, phylogenetic analysis of human parvovirus B19 revealed genotype I in these six patients. CONCLUSION: In this study, acute B19 infections were detected in patients with beta thalassemia major. Screening of such high-risk groups can considerably reduce the incidence and prevalence of B19 infection; thus, screening is required for epidemiologic surveillance and disease-prevention measures.
Adult ; beta-Thalassemia* ; Blood Transfusion ; Cross-Sectional Studies ; DNA ; Epidemiological Monitoring ; Erythrocytes ; Erythroid Precursor Cells ; Genotype ; Humans* ; Incidence ; Iran* ; Mass Screening ; Parvovirus ; Parvovirus B19, Human* ; Plasma ; Prevalence ; Real-Time Polymerase Chain Reaction ; Thalassemia ; Tropism

Background: This study was designed to evaluate and compare the diagnostic value of magnetic resonance imaging (MRI) and indirect magnetic resonance arthrography (I-MRA) imaging with those of arthroscopy and each other. Methods: This descriptive-analytical study was conducted in 2020. All patients who tested positive for labrum lesions during that year were included in the study. The patients underwent conservative treatment for 6 weeks. In the event of no response to conservative treatment, MRI and I-MRA imaging were conducted, and the patients underwent arthroscopy to determine their ultimate diagnosis and treatment plan. Imaging results were assessed at a 1-week interval by an experienced musculoskeletal radiologist. Image interpretation results and arthroscopy were recorded in the data collection form. Results: Overall, 35 patients comprised the study. Based on the kappa coefficient, the results indicate that the results of both imaging methods are in agreement with the arthroscopic findings, but the I-MRA consensus rate is higher than that of MRI (0.612±0.157 and 0.749±0.101 vs. 0.449±0.160 and 0.603±0.113). The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of MRI in detecting labrum tears were 77.77%, 75.00%, 91.30%, 50.00%, and 77.14%, respectively, and those of I-MRA were 88.88%, 75.00%, 92.30%, 66.66%, and 85.71%. Conclusions Here, I-MRA showed higher diagnostic value than MRI for labral tears. Therefore, it is recommended that I-MRA be used instead of MRI if there is an indication for potential labrum lesions.