Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Can MRI Replace Nasopharyngoscopy in the Evaluation of Velopharyngeal Insufficiency?

OBJECTIVE

To investigate whether flexible nasopharyngoscopy, when performed in addition to magnetic resonance imaging (MRI), influences the type of surgery selected or success of surgery in patients with velopharyngeal insufficiency (VPI).

DESIGN

Cohort study.

SETTING

A metropolitan children's hospital.

PATIENTS

Patients with non-syndromic, repaired cleft palate presenting for management of VPI.

INTERVENTIONS

MRI and nasopharyngoscopy or MRI alone for preoperative imaging of the velopharyngeal mechanism.

MAIN OUTCOME MEASURES

(1) Surgical selection and (2) resolution of hypernasality. All speech, MRI, and nasopharyngoscopy measurements were performed by raters blinded to patients' medical and surgical history.

RESULTS

Of the 25 patients referred for nasopharyngoscopy, 76% completed the exam. Of the 41 patients referred for MRI, the scan was successfully completed by 98% of patients. Completion of nasopharyngoscopy was significantly (p=0.01) lower than MRI. Surgical selection did not significantly differ (p=0.73) between the group receiving MRI and nasopharyngoscopy and the group receiving MRI alone, nor was there a significant difference between these groups in the proportion of patients achieving resolution of hypernasality postoperatively (p=0.63). Percent total velopharyngeal closure assessments on nasopharyngoscopy and MRI were strongly correlated (r=0.73).

CONCLUSIONS

In patients receiving MRI as part of their preoperative VPI evaluation, the addition of nasopharyngoscopy did not result in a difference in surgical selection or resolution of hypernasality. Routine inclusion of nasopharyngoscopy may not be necessary for the evaluation of velopharyngeal anatomy when MRI is available.

Surgical Management of Velopharyngeal Dysfunction

Velopharyngeal dysfunction (VPD) is caused by inadequate closure of the velopharyngeal port. VPD can hinder a child's ability to communicate and can impact his/her quality of life. Evaluation of children with VPD is often completed in a multidisciplinary setting and often involves studies that allow for the visualization of the velopharyngeal closure during voluntary speech (ie, nasopharyngoscopy). Multiple surgical options exist for the treatment of VPD including pharyngeal flap, sphincter pharyngoplasty, buccal myomucosal flaps, Furlow palatoplasty, palate re-repair, intravelar veloplasty, and injection pharyngoplasty. Each speech surgery has its unique benefits and drawbacks and the decision on which surgery to recommend should be tailored to each patient's specific needs and weighing the risk/benefit profile for their specific surgeries.

Measurement Matters: MRI Analysis of Differing Anatomic Measurement Techniques for Velar Length and the Velopharyngeal Needs Ratio

Background

Advances in imaging tools provide opportunities to enhance how velopharyngeal (VP) variables are quantified to facilitate surgical decisions. The purpose of this study was to use magnetic resonance imaging (MRI) to determine if quantitative differences were present between measures of linear and curvilinear velar length, and subsequently, the VP needs ratio.

Methods

Data were prospectively collected from patients presenting with repaired cleft palate and/or congenital palatal insufficiency with or without VPI at a single center tertiary children's hospital. Quantitative measures of the velopharynx using a novel nonsedated MRI protocol were obtained. Paired samples t tests were conducted to assess if differences were present between the VP needs ratio and measurements of linear and curvilinear velar length at rest and during sustained phonation. Intraclass correlation coefficients were calculated to assess intra/inter-rater reliability.

Results

Significant differences were present between measurements of linear and curvilinear velar length at rest (P ≤ 0.001) and during sustained phonation (P ≤ 0.001). Significant differences were also present in the VP needs ratio (P ≤ 0.001). Curvilinear velar length at rest and during sustained phonation was longer than that of linear velar length at rest and during sustained phonation. No significant differences were observed between measures of effective velar length (P = 0.393).

Conclusions

Measurement differences influence the VP needs ratio. This may have implications for comparisons to previously reported normative reference values and for those who are anatomically at risk for VPI. MRI provides an enhanced imaging modality to assess normative benchmarks and the anatomic variables used to define VP anatomy for clinical decision-making.

The Pediatric Neuroradiologist's Practical Guide to Capture and Evaluate Pre- and Postoperative Velopharyngeal Insufficiency

Up to 30% of children with cleft palate will develop a severe speech disorder known as velopharyngeal insufficiency. Management of velopharyngeal insufficiency typically involves structural and functional assessment of the velum and pharynx by endoscopy and/or videofluoroscopy. These methods cannot provide direct evaluation of underlying velopharyngeal musculature. MR imaging offers an ideal imaging method, providing noninvasive, high-contrast, high-resolution imaging of soft-tissue anatomy. Furthermore, focused-speech MR imaging techniques can evaluate the function of the velum and pharynx during sustained speech production, providing critical physiologic information that supplements anatomic findings. The use of MR imaging for velopharyngeal evaluation is relatively novel, with limited literature describing its use in clinical radiology. Here we provide a practical approach to perform and interpret velopharyngeal MR imaging examinations. This article discusses the velopharyngeal MR imaging protocol, methods for interpreting velopharyngeal anatomy, and examples illustrating its clinical applications. This knowledge will provide radiologists with a new, noninvasive tool to offer to referring specialists.

Sex Differences in Velopharyngeal Anatomy of 9- and 10-Year-Old Children

OBJECTIVE

Understanding the normal anatomy of velopharyngeal (VP) mechanism and the emergence of sexual dimorphism provides valuable insights into differences of VP anatomy among males and females. The purpose of this study is to examine sex differences in VP anatomy in a large data set of 3,248 9- and 10-year-old children.

METHOD

Static three-dimensional magnetic resonance imaging was used to compare five VP characteristics including velar length, velar thickness, effective velar length, levator veli palatini muscle length, and pharyngeal depth between age-matched males (n = 1,670) and females (n = 1,578). Additionally, these dimensions were used to determine the VP ratio and effective VP ratio.

RESULTS

Males showed significantly larger dimensions for all VP distances and significantly lower ratios of velar length and effective velar length to pharyngeal depth (p < .05). The magnitude of these effect sizes was small to medium, with Cohen's d values ranging from 0.12 to 0.63. Additionally, the VP ratio and effective VP ratio are lower among males compared to females (p < .05).

CONCLUSIONS

Results suggest the presence of sexual dimorphism in the VP mechanism among 9- and 10-year-old children. These findings emphasize the necessity of using different normative data for males and females when making comparisons to patients with cleft palate.

Real-time speech MRI datasets with corresponding articulator ground-truth segmentations

The use of real-time magnetic resonance imaging (rt-MRI) of speech is increasing in clinical practice and speech science research. Analysis of such images often requires segmentation of articulators and the vocal tract, and the community is turning to deep-learning-based methods to perform this segmentation. While there are publicly available rt-MRI datasets of speech, these do not include ground-truth (GT) segmentations, a key requirement for the development of deep-learning-based segmentation methods. To begin to address this barrier, this work presents rt-MRI speech datasets of five healthy adult volunteers with corresponding GT segmentations and velopharyngeal closure patterns. The images were acquired using standard clinical MRI scanners, coils and sequences to facilitate acquisition of similar images in other centres. The datasets include manually created GT segmentations of six anatomical features including the tongue, soft palate and vocal tract. In addition, this work makes code and instructions to implement a current state-of-the-art deep-learning-based method to segment rt-MRI speech datasets publicly available, thus providing the community and others with a starting point for developing such methods.

Comparative Effectiveness of Secondary Furlow and Buccal Myomucosal Flap Lengthening to Treat Velopharyngeal Insufficiency

Background

Secondary Furlow (Furlow) and buccal myomucosal flaps (BMMF) treat velopharyngeal insufficiency by lengthening the palate and retropositioning the levator veli palatini muscles. The criteria for choosing one operation over the other remain unclear.

Methods

A single-center retrospective cohort study was conducted. Thirty-two patients with nonsyndromic, repaired cleft palate were included. All patients underwent a Furlow or BMMF. Outcome measures included (1) resolution of hypernasality 12 months postoperatively, (2) degree of improvement of hypernasality severity; and (3) change in velar length, as measured on magnetic resonance imaging scans obtained preoperatively and 12 months postoperatively. All measures were performed by raters blinded to participants' medical and surgical history.

Results

Hypernasality was corrected to normal in 80% of the Furlow group and in 56% of the BMMF group. Patients receiving BMMF had more severe hypernasality during preoperative speech evaluation. Both groups had a median decrease of two scalar rating points for severity of hypernasality (P = 0.58). On postoperative magnetic resonance imaging, patients who underwent Furlow had a median increased velar length of 6.9 mm. Patients who received BMMF had a median increased velar length of 7.5 mm. There was no statistically significant difference between groups regarding increase in velar length (P = 0.95).

Conclusions

Furlow and BMMF procedures increase velar length with favorable speech outcomes. The same degree of improvement for hypernasality was observed across groups, likely explained by the similar increase in velar length achieved. Anatomic changes in palate length and levator veli palatini retropositioning persist 1 year after surgery.

Can Velopharyngeal MRI be Used in Individuals with Orthodontic Devices?

OBJECTIVE

To evaluate the influence of common pediatric orthodontic appliances on velopharyngeal (VP) MRI and to compare MR image sequences to determine if sequence parameters impact the visibility of key VP structures commonly assessed in clinical VP MRI.

DESIGN

Participants undergoing orthodontic treatment completed a VP MRI study. Level of distortion caused by orthodontic devices on 8 anatomical sites of interest and using variable MRI sequences was evaluated.

SETTING

Single institution.

PARTICIPANTS

Nineteen participants undergoing orthodontic treatment.

MAIN OUTCOME

Level of distortion caused by metal artifacts and MR sequence used.

RESULTS

The results of this study demonstrate that appliances such as hyrax palatal expanders and braces with stainless steel brackets are acceptable for a VP MRI, while class II corrector springs are not recommended. The HASTE MRI sequence with 2D imaging techniques should be utilized if the child has orthodontic devices, while FSE and 3D imaging techniques are not recommended. The presence of wire spring coils and molar bands are likely to not to interfere with the MRI evaluation.

CONCLUSIONS

Findings from this study suggest that the presence of orthodontic appliances does not hinder visualization of all velopharyngeal structures during an MRI. Therefore, careful consideration must be made prior to disqualifying or recommending patients for VP MRI.

Preliminary Development of an MRI Atlas for Application to Cleft Care: Findings and Future Recommendations

OBJECTIVE

To introduce a highly innovative imaging method to study the complex velopharyngeal (VP) system and introduce the potential future clinical applications of a VP atlas in cleft care.

DESIGN

Four healthy adults participated in a 20-min dynamic magnetic resonance imaging scan that included a high-resolution T2-weighted turbo-spin-echo 3D structural scan and five custom dynamic speech imaging scans. Subjects repeated a variety of phrases when in the scanner as real-time audio was captured.

SETTING

Multisite institution and clinical setting.

PARTICIPANTS

Four adult subjects with normal anatomy were recruited for this study.

MAIN OUTCOME

Establishment of 4-D atlas constructed from dynamic VP MRI data.

RESULTS

Three-dimensional dynamic magnetic resonance imaging was successfully used to obtain high quality dynamic speech scans in an adult population. Scans were able to be re-sliced in various imaging planes. Subject-specific MR data were then reconstructed and time-aligned to create a velopharyngeal atlas representing the averaged physiological movements across the four subjects.

CONCLUSIONS

The current preliminary study examined the feasibility of developing a VP atlas for potential clinical applications in cleft care. Our results indicate excellent potential for the development and use of a VP atlas for assessing VP physiology during speech.