RESUMO
OBJECTIVE: To analyze the anatomical changes of the IV ventricle and cisterna magna in the Chiari malformation I (CMI) and basilar invagination (type B). METHODS: This is a controlled study with 161 exams of magnetic resonance imaging (MRI) of adults grouped into control (n = 37), basilar invagination (BI; n = 31), Chiari malformation I (CMI; n = 37), and CMI+BI (n = 56). The MRIs were analyzed using the visualization software Osirix (Pixmeo, Bernex, Geneva, version 3.8.2). The morphometric variables were: distance from the obex to the McRae line; length of the IV ventricle floor; and the area and volume of the cisterna magna. The univariate ANOVA followed by Tukey's post-hoc test was applied to evaluate the difference between the groups. The difference between sexes was evaluated by the t test for each group. RESULTS: Alterations in the cisterna magna and IV ventricle were more evident only in the CMI and CMI+BI groups. For both sexes, the CMI and CMI+BI groups showed: a reduction in the CSF space (P < 0.001), cisterna magna with volume reduction (P < 0.001), low position of the obex (P < 0.001), and IV ventricle more elongated (male P = 0.007 and female P < 0.001). The BI group had no significant change in the analysis by sex. CONCLUSIONS: The CMI (isolated and associated with BI) showed a low obex position and elongation of the IV ventricle due to traction towards the spinal canal. The reduction of cisterna magna volume added to the occupation of the cerebellar tonsils can impact in the cerebrospinal fluid dynamics. The BI when isolated was not related to alterations in the parameters of cerebrospinal fluid spaces studied.
Assuntos
Malformação de Arnold-Chiari , Platibasia , Adulto , Humanos , Masculino , Feminino , Cisterna Magna/diagnóstico por imagem , Platibasia/complicações , Malformação de Arnold-Chiari/diagnóstico por imagem , Malformação de Arnold-Chiari/complicações , Imageamento por Ressonância Magnética , Quarto Ventrículo/diagnóstico por imagemRESUMO
OBJECTIVE: The present study aims to perform a reproducibility study of the clivus-canal angle (CCA), Welcker's basal angle (WBA), and the distance from the odontoid process to Chamberlain's line (DOCL) on magnetic resonance imaging (MRI). MATERIALS AND METHODS: Two medical students and two radiologists respectively evaluated 100 and 50 consecutive MRI scans of adult skulls, selected randomly. Each examiner, working independently and blinded to the previous results, performed readings for each patient on two different occasions. Measurements were performed in T1-weighted sequences acquired in the midsagittal plane. The levels of intraobserver reproducibility and interobserver agreement were evaluated by calculating the intraclass correlation coefficients (ICCs) and the corresponding 95% confidence intervals. RESULTS: The mean values obtained by the examiners were 150º for the CCA, 130º for the WBA, and 2.5 mm for the DOCL. The ICC for interobserver agreement was 0.980, 0.935, and 0.967, for the CCA, WBA, and DOCL, respectively, for the students, compared with 0.977, 0.941, and 0.982, respectively, for the radiologists, and 0.980, 0.992, and 0.990, respectively, for all of the examiners together. In the analysis of intraobserver agreement, the ICC ranged from 0.929 to 0.959 for the CCA, from 0.918 to 0.964 for the WBA, and from 0.918 to 0.981 for the DOCL. CONCLUSION: The measurement of the CCA, WBA, and DOCL appears to show excellent intraobserver reproducibility and interobserver agreement on MRI.
OBJETIVO: Realizar um estudo de reprodutibilidade do ângulo clivocanal (ACC), ângulo basal de Welcker (ABW) e distância do odontoide à linha de Chamberlain (DOLC) em ressonância magnética (RM). MATERIAIS E MÉTODOS: Quatro examinadores, dois graduandos de medicina e dois radiologistas, avaliaram, respectivamente, 100 e 50 indivíduos adultos submetidos a RM de crânio, consecutiva e aleatoriamente. Cada um realizou duas leituras para cada paciente em diferentes ocasiões, de forma cega e independente. As análises de concordância intraobservador e interobservador foram realizadas pelo coeficiente de correlação intraclasse (CCI), com intervalo de confiança de 95%. RESULTADOS: As medidas médias, considerando todos os examinadores, foram: ACC = 150º, ABW = 130º, DOLC = 2,5 mm. A análise interobservador entre os estudantes revelou CCI de 0,980, 0,935 e 0,967 para ACC, ABW e DOLC, respectivamente, e para os radiologistas, CCI de 0,977, 0,941 e 0,982, respectivamente. A análise interobservador entre estudantes e radiologistas revelou CCI de 0,980, 0,992 e 0,990, respectivamente. Em relação à análise intraobservador, as medidas do ACC tiveram CCI variando entre 0,929 e 0,959, ABW entre 0,918 e 0,964 e DOLC entre 0,918 e 0,981. CONCLUSÃO: ACC, ABW e DOLC obtiveram excelentes reprodutibilidades intraobservador e interobservador na RM.