Clinical utility of SPECT/CT and CT-dacryocystography-enhanced dacryoscintigraphy in the imaging of lacrimal drainage system obstruction

Abstract

PurposeEpiphora is commonly caused by a relative or complete occlusion in the lacrimal drainage system (LDS), principally a nasolacrimal duct obstruction (NLDO). Dacryoscintigraphy (DSG), an extensively assessed imaging technique in diagnosing its abnormalities, can provide only planar images, according to which it needs to be improved. Our aim was to evaluate clinical utility of simultaneous DSG and single-photon emission computed tomography/computed tomography (SPECT/CT) combined with computed tomographic dacryocystography (CT-DCG) in the evaluation of LDS.MethodsDynamic imaging with DSG was performed, and tracer radioactivity was detected by a gamma camera. Successively, SPECT/CT images of the involved region were gained, followed by CT-DCG, during which a contrast medium was syringed into the affected LDS, and finally contrast CT scans were obtained again from the same region.ResultsFifty-seven patients, mean age 54.25 (± 18.26) years all with unilateral NLDO and 32 control subjects, all with patent LDS, mean age 49.88 (± 18.61) years were evaluated in the study. Delayed outflow of tearing eyes was exposed to DSG compared to the fellow and control eyes. The highest value for sensitivity was observed for SPECT/CT, followed by CT-DCG and DSG techniques, while combining DSG with SPECT/CT, DSG with CT-DCG, and SPECT/CT with CT-DCG, the sensitivity increased to 96.49%, 92.98%, and 94.73%, respectively.ConclusionsAlthough DSG is a sensitive nuclear medicine method, it only provides useful clinical data when simultaneously supplemented with SPECT/CT and CT-DCG trials as they jointly can offer valuable information about the localization of an abnormality and verify stenosis or obstruction.

Avaliação da obstrução das vias lacrimais por dacriocistografia: ensaio iconográfico

“…O sistema de drenagem lacrimal possui três estreitamentos anatômicos, nos quais as obstruções são mais comumente encontradas: válvula de Rosenmüller, na junção do canalículo comum com o saco lacrimal (Figuras 2 e 3); válvula de Krause, na junção do saco lacrimal com ducto nasolacrimal (Figuras 4 e 5); e válvula de Hasner, na abertura do ducto nasolacrimal para a cavidade nasal (Figura 6). 1 A existência da válvula de Rosenmüller é questionada por alguns autores, que consideram tratar-se apenas do ângulo formado pela junção do canalículo lacrimal comum com a parede lateral do saco lacrimal. 7,8 Figura 2: Dacriocistografia com obstrução alta da válvula de Rosenmüller à esquerda.…”

“…Representação esquemática (A), dacriocistografia convencional positiva (B) e conversão negativa (C). Foi procedida a cateterização do orifício lacrimal superior (seta branca), evidenciando-se opacificação do canalículo lacrimal superior (CLS) e refluxo do contraste (*), sem progressão do mesmo ao nível da válvula de Rosenmüller (1). Figura 4: Dacriocistografia com obstrução baixa da válvula de Krause à esquerda.…”

“…A epífora, lacrimejamento excessivo, é uma queixa comum na prática oftalmológica. 1 Existem duas categorias de etiologia: lacrimejamento reflexo, relacionado a fatores como olho seco, inflamação, alergias, hipersecreção primária das glândulas lacrimais, entre outros; e redução do fluxo lacrimal, ocasionado por mau posicionamento da pálpebra, disfunção da bomba lacrimal ou obstrução em qualquer parte do sistema de drenagem nasolacrimal. 2 A causa mais comum de epífora corresponde a obstrução das vias lacrimais.…”

Imaging in Disorders of the Lacrimal Drainage System

“…One drop of 99m Tc-sodium pertechnetate is instilled in each eye. Patients are made to sit in front of a gamma camera and his head is stabilized and the passage of tracer through the lacrimal drainage system is detected by a gamma camera to obtain DSG images [46]. Sequential images are taken at specific intervals [43,44] specific intervals of 2.5, 5, 7.5, and 10 min [43].…”

“…Thus, physiological dysfunctions with post-sac delay can cause functional obstruction of lacrimal drainage system [47]. Dacryocystography is a sensitive method for lacrimal drainage system evaluation but the useful clinical information is only possible by supplementing it with CT DCG to localize any obstruction [46].…”