Detection of perilymphatic fistula in labyrinthine windows by virtual endoscopy and variation of reconstruction thresholds on CT scan

Abstract

Background: Perilymphatic fistula (PLF) is a breach in a labyrinthine window. The opening might decrease the radiological density of the window.

Aims/objectives: To evaluate the radiological density of the labyrinthine windows by virtual endoscopy on CT scan.

Materials and methods: This prospective study included 47 adult patients with PLF and 98 control patients. Diagnosis of PLF was based on a composite radio clinical score and/or intra operative visualization of the fistula and/or resolution of the symptoms after surgery. On routine CT-scan, labyrinthine windows were examined by virtual endoscopy. The reconstruction threshold was gradually increased until a virtual opening appeared (opening threshold [OT]) and compared to the contralateral window (OT difference).

Results: The OT difference was higher in patients than in controls (60.2 ± 10.36 (SEM), n = 47 versus 28.0 ± 2.29 Hounsfield units (HUs), n = 98, p < .01 unpaired t-test). A ROC analysis showed that at an OT difference of 31.5 UH had a sensitivity of 75% and a specificity of 75% for the PLF diagnosis.

Conclusions: CT-scan virtual endoscopy and threshold variation provided high specificity and sensitivity in the PLF diagnosis.

Significance: This post processing of radiological data appears to enhance the diagnostic value of CT scan.

Chinese abstract

背景：外淋巴瘘（PLF）是迷路窗的破口。这个开口可能会降低迷路窗的辐射密度。

目的：在CT扫描上应用虚拟内窥镜评价迷路窗的放射密度。

材料与方法：本前瞻性研究包括47例成人PLF患者和98例对照患者。PLF的诊断是基于一个综合的放射临床评分和/或术中瘘管可视化和/或术后症状缓解。常规CT扫描采用虚拟内窥镜检查迷路窗。重建阈值逐渐增加, 直到出现虚拟开口（开口阈值[OT]）, 并与对侧窗（OT差）比较。

结果：与对照组比较, 两组OT差异有显著性（60.2±10.36（SEM）, n=47相对于28.0±2.29 Hounsfield单位（HUs）, n=98, p<0.01）。ROC分析显示, 在OT差为31.5HU时, PLF诊断的敏感性为75%, 特异性为75%。

结论：CT扫描虚拟内镜及阈值变化为PLF的诊断提供高特异性和敏感性。

意义：对影像学数据的后处理有助于提高CT扫描的诊断价值。

Keywords:

• Perilymphatic fistula
• radiological density
• virtual endoscopy
• CT scan
• barotrauma
• head injury

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge the financial support of Société ORL de Bourgogne for this study.