Comparação entre as técnicas de dacriocistografia por ressonância magnética e por raios X no diagnóstico da obstrução das vias lacrimais / Comparison between magnetic resonance and x-ray dacryocystography in the evaluation of the obstruction of the lacrimal apparatus

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Epiphora is the hyperlachrymation related to an obstruction of the lachrymal drainage system. In such cases, the treatment is frequently surgical and the definition of the nature and level of obstruction demands imaging methods. Magnetic Resonance Imaging (MRI) may play a role in this issue. Objectives: Evaluate the efficacy of MR dacryocystography in the obstruction of the lachrymal drainage system, comparing the results to the gold standard imaging method (X-ray dacryocystography - DCG). Methods: The study comprised 32 patients (26 women and 6 men, mean age 55.4 ± 21.5 years), with a time course of symptoms ranging from 3 months to 20 years. They were evaluated using a STIR T2 sequence, without and with the instillation of saline solution and a Gradient-echo T1 sequence after instillation of 1:100 diluted gadolinium. The MRI findings were compared to the DCG ones. Two different observers performed the analysis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for each MRI sequence, regarding the detection of the obstruction of the lachrymal apparatus. Intra and interobserver agreement were calculated for the detection of the obstruction and for the determination of the level of obstruction, using the Fischer exact test and Kappa index - K (statistical significance p <0,001). Results: Regarding the detection of obstruction, MRI sequences presented sensitivity ranging from 91.9% to 93.2%, specificity ranging from 80,3% to 100%, PPV ranging from 88.7% to 100% and NPV ranging from 83.2% to 87.8%. Kappa index revealed high intra and interobserver values (ranging from 0.716 to 1.000). Regarding the determination of the level of obstruction, the results for each observer were different. For Observer 1, the STIR T2 sequence after instillation of saline solution was the only one to be statistically concordant to DCG (K = 0.582). Otherwise, for Observer 2, all MR sequences were statistically concordant to DCG (K ranging from 0.404 to 0.623). Conclusions: MRI may be considered in the radiological evaluation of patients with epiphora, due to its high sensitivity and specificity, as well as consistent intra and interobserver agreement rates. When the lachrymal drainage system is not filled with any kind of content in the MRI examination, other imaging modalities must be considered, for differentiation between upper system obstruction and functional disease

ASSUNTO(S)

diagnostic techniques and procedures radiografia magnetic resonance imaging técnicas de diagnóstico e procedimentos lacrimal apparatus aparelho lacrimal doenças do aparelho lacrimal lacrimal apparatus diseases imagem por ressonância magnética radiography

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