Velopharyngeal closure analysis using four-dimensional computed tomography: a pilot study of healthy volunteers and adult patients with cleft palate

Abstract

Background Nasopharyngoscopy is a common method to evaluate velopharyngeal closure in patients with cleft palate. However, insertion of a fiberoptic nasopharyngoscope causes discomfort in patients. The aim of this study was to estimate the reliability of short-time exposure images obtained using 320-row area detector computed tomography (320-ADCT) as a novel evaluation method for the assessment of velopharyngeal function. Methods We evaluated five healthy adult volunteers and five postoperative adult patients with cleft palate. During a 3.3-s imaging exposure, the participants were asked to perform two tasks: nasal inspiration and subsequent oral expiration through a catheter into a water-filled cup. The movement of the velopharyngeal structures was recorded during each examination, and the presence of velopharyngeal insufficiency (VPI) and velopharyngeal closure (VPC) patterns were estimated. If VPI was detected, the cross-sectional area was also calculated. Cohen’s kappa and weighted kappa coefficients were used to evaluate the concordance of nasopharyngoscopy and 320-ADCT evaluation. Results Speech pathology evaluation did not reveal hypernasality in any study participant. Micro-VPI was detected by nasopharyngoscopy in one healthy volunteer and two patients. 320-ADCT detected micro-VPI in two more patients. The cross-sectional area of the VPI in these subjects ranged from 2.53 to 16.28 mm 2 . Nasopharyngoscopy and 320-ADCT were concordant in detecting VPI in eight participants (κ = 0.6) and in assessing VPC patterns in nine (κ = 0.82). Moreover, images obtained using 320-ADCT allowed for reduced dead angle and, thus, easy detection of micro-VPI and Passavant’s ridges. Conclusion Although the radiation exposure cannot be ignored, our novel evaluation method using 320-ADCT enables more detailed evaluation of VPC than nasopharyngoscopy. Future studies should investigate the relationship between 320-ADCT findings and speech pathology evaluations. Electronic supplementary material The online version of this article (10.1186/s12880-019-0350-4) contains supplementary material, which is available to authorized users.

Early experience with four-dimensional computed tomography for observing velopharyngeal closure function in pediatric patients and the evaluation of the exposure dose

“…The VPC patterns were evaluated as circular and circular with Passavant's ridge; however, two patients had unevaluable images. This nding was similar to the assessment of adult postoperative cleft patients reported in our past study: four patients had the circular pattern and one patient had the circular with Passavant's ridge pattern [2]. However, some participants in the current study demonstrated compensatory behavior during blowing to overcome the malfunction.…”

“…In that study, we evaluated 10 adult volunteers, which included ve patients with postoperative cleft. We concluded that nasopharyngoscopy and 4D evaluation with 320-ADCT had a high concordance rate for evaluating VPI (8/10 patients) and VPC patterns (9/10 patients) [2].…”

“…In 2019, we reported a modi ed scan protocol that shortened the exposure time during VPF assessment [2].…”

“…CT imaging using a 320-ADCT scanner (Aquilion ONE/Genesis Edition; Toshiba Medical Systems Corp., Tochigi, Japan) was conducted, using the method described in our previous report [2]. Each participant lay horizontally on the bed, and performed two successive tasks following the signal of the examiner: nasal inspiration, followed by oral expiration through a catheter into a water-lled cup.…”

“…In 2019, we reported a four-dimensional (4D) evaluation method that appends the time phase image to threedimensional (3D) images for the assessment of velopharyngeal closure (VPC) by using 320-row area detector computed tomography (320-ADCT) images acquired from adult volunteers; this method was named "virtual nasopharyngoscopy" [2]. When using this method, the time and dose of exposure were reduced, compared to those of a previously reported method [3].…”