Original Article 273 Comparison of Imaging Softwares for Upper Airway Evaluation: Preliminary Study 1 Department of Diagnosis and Surgery, Dental School of Araraquara, São Paulo State University, Araraquara, São Paulo, Brazil 2 Department of Radiology, Aarhus University, Aarhus, Denmark 3 Department of Cranio-Maxillofacial Surgery, University Hospital Basel, Basel, Switzerland Address for correspondence Guilherme dos Santos Trento, DDS, PhD Student, Department of Diagnosis and Surgery, Faculdade de Odontologia Campus de Araraquara, Universidade Estadual Paulista Julio de Mesquita Filho, 1680th Humaitá Street, Araraquara, São Paulo 14801-903, Brazil (e-mail: guilhermetrento@yahoo.com.br). Craniomaxillofac Trauma Reconstruction 2018;11:273–277 Abstract Keywords ► imaging software ► CBCT ► posterior airway The interest about upper airway evaluation has increased lately. Therefore, many softwares have been developed aiming to improve and facilitate the analysis of airway volume. The objective of this study was to compare two different softwares packages, Mimics and Dolphin, in their accuracy and precision in upper airway space measurements. Preoperative cone beam computed tomography scans of nine nonsyndromic patients submitted to surgically assisted rapid maxillary expansion were included in this study. The imaging exams were converted to DICOM (digital imaging and communications in medicine) files and imported to the softwares. The mean volume for the Dolphin group (G1) was 10.791 cm3 (SD ¼ 4.269 cm3) and for the Mimics group (G2) was 10.553 cm3 (SD ¼ 4.564 cm3). There was no statistically significant difference between the two groups (p ¼ 0.105). Upper airway (UA) evaluation can be performed through adequate imaging exams. Furthermore, those imaging exams may assist the diagnosis of respiratory problems associated with dentofacial deformities.1 Traditionally, the UA space is evaluated by lateral cephalometric radiography.2 However, nowadays cone beam computed tomography (CBCT) is widely used for UA evaluation due to the three-dimensional (3D) assessment of UA with high spatial resolution between the soft tissues and airway space.3,4 As CBCT scan became fairly used in oral and maxillofacial surgery, many softwares were developed to evaluate anatomical structures in details.5 Those software packages use digital imaging and communications in medicine (DICOM) files.6 Moreover, many of those softwares have optional tools responsible to segment and measure the UA space.3 Despite the evolution of the software packages in the assessment of the UA space, some aspects are very important to achieve trustworthy results, such as respiration and tongue position during the exam, mandible morphology, and definition of the anatomical limits.7 Guijarro-Martínez and Swennen3 performed a systematic review of UA evaluation and reported 18 softwares used for volumetric UA evaluation using CBCT scans. Among those softwares, Mimics (Materialise Interactive Medical Image Control System, Leuven, Belgium) and Dolphin (Dolphin Imaging and Management Solutions, Chatsworth, CA) were selected. Burkhard et al8 compared Mimics software to other two softwares, OsiriX 64-bit (Bernex, Switzerland) and BrainLab (Munich, Germany), demonstrating similar UA measurements. Similarly, El and Palomo9 presented that Dolphin and the other two different softwares had a high reliability in UA space measurements. The aim of this study is to compare two different softwares packages, Mimics and Dolphin, in their accuracy and precision in posterior airway space measurements. According to the authors, there is no study that compares these two softwares. received April 7, 2017 accepted after revision May 27, 2017 published online August 25, 2017 Copyright © 2018 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662. DOI https://doi.org/ 10.1055/s-0037-1606247. ISSN 1943-3875. This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. Guilherme dos Santos Trento, DDS, PhD Student1 Lucas Borin Moura, DDS, PhD Student1 Rubens Spin-Neto, DDS, MS, PhD2 Philipp Christian Jürgens, MD, MS, PhD3 Marisa Aparecida Cabrini Gabrielli, DDS, MS, PhD1 Valfrido Antônio Pereira-Filho, DDS, MS, PhD1 Comparison of Imaging Softwares for Upper Airway Evaluation was normal and paired t-test was performed considering a 95% confidence interval. Materials and Methods This pilot study was submitted and approved by the Ethics Committee of the Dental School of Araraquara—São Paulo State University, UNESP (protocol number 0036/09). The preoperative CBCT scans of nine nonsyndromic patients submitted to surgically assisted rapid maxillary expansion were included. The imaging data were collected from records of the Diagnosis and Surgery Department, UNESP. All patients underwent the CBCT scan in the same scanner (iCAT, Imaging Science International, Hatfield, PA). The following scanning protocol was used in obtaining all the images. The patients were placed in natural head position and instructed to make a deep inspiration and hold their breath. Also, patients were requested to maintain the tongue in the palate and to avoid swallowing during the scanning. After the exam, the DICOM files were imported into the Dolphin and Mimics softwares (►Figs. 1 and 2). Two groups were created according to the software used (G1: Dolphin; G2: Mimics). Each specific software tool was used to measure the UA volume. The volumetric region of interest was defined selecting a midsagittal image of the airway and determining the superior and inferior limits. Both limits were traced parallel to the Frankfurt plane. The superior limit was determined by the posterior nasal spine, and the inferior limit was determined by the most anteroinferior point of C2 (►Fig. 3). A single operator made all the measurements repeatedly in different moments presenting no significant differences between the periods. Statistical analysis was performed between the two groups. The data distribution Fig. 1 3D reconstruction and demarcation of the space airway in Mimics software. Craniomaxillofacial Trauma and Reconstruction dos Santos Trento et al. Vol. 11 No. 4/2018 Results Among the nine included patients, seven patients were female and two were male. The mean age was 32.77 years (SD ¼ 7.31 years) ranging from 21 to 40 years. All patients had transversal deficiency of the maxilla as dentofacial deformity. ►Table 1 and ►Fig. 4 show the measurements according to group and patient. All values were registered in cubic centimeters. The mean volume for the Dolphin group (G1) was 10.791 cm3 (SD ¼ 4.269 cm3) and that for the Mimics group (G2) was 10.553 cm3 (SD ¼ 4.564 cm3). There was no statistically significant difference between the two groups (p ¼ 0.105). Discussion Historically, UA space measurements started using lateral cephalometric radiographs; however, one of their major limitations was the restriction to two-dimensional (2D) analyses. Nowadays, CBCT is considered the gold standard exam because of its high accuracy and possibility to perform 3D measurements.10,11 Also, this exam has become much more affordable in dentistry.12 Although some authors have shown controversy regarding the measurements obtained from the CBCT,13 this study corroborates to others14,15 that already proved the accuracy of CBCT in UA space measurements. Furthermore, Cheng et al16 presented that UA reconstruction and segmentation through CBCT’s softwares is quite reliable.14–16 The UA evaluation through CBCT requires some attention during image acquisition. There are some factors that may distort the results during or even before scanning, such as breathing, tongue position, and head movement.17 Muto et al18 stated that alterations of head and neck inclination produced by head extension were correlated with changes in the dimension of UA space. Therefore, any movement of the patient could affect the results of the imaging exam. To obtain uniform results, all scanning was performed by following a described protocol. Another limitation about measurements of UA space is the comparison between them, regarding the calculated volumes and regions. This problem occurs due to the differences among all studies regarding the determination of UA limits. As a matter of fact, there are no standard UA limits, and even some studies do not clearly show how the UA area was determined.3,7 Another important point for UA measurements is the way how the volume is segmented: automatic or manual. Manual segmentation may enable great control by the operator, resulting in optimal accuracy; however, it requires more operation time.9 The sample evaluated in our study was analyzed manually. However, Ghoneima and Kula19 measured the volume and area of an acrylic airway model using CBCT data by Dolphin software. They found no statistically This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. 274 dos Santos Trento et al. Fig. 2 3D reconstruction and demarcation of the space airway in Dolphin software. Fig. 3 Delimitation of the area and evaluation of volume of the space airway in Dolphin software. Table 1 Upper airway volume (cm3) according to patient and software Patient Dolphin (G1) Mimics (G2) 1 16.424 16.332 2 4.788 4.477 3 6.897 6.317 4 10.631 10.154 5 17.881 18.554 6 7.388 6.942 7 10.330 9.881 8 11.597 11.141 9 11.181 11.180 Mean 10.791 10.553 SD 4.269 4.564 Paired t-test 0.1055 significant differences between the manual and the digital measurements, thus proving the accuracy and reliability of the software for both 2D and 3D analysis. In general, some studies use an acrylic model as a gold standard aiming to prove the reliability and accuracy of the measurements. An acrylic model consists of an air-filled plastic rectangular prism surrounded by water. This phantom has the possibility of the real measurements with a caliper and the measurements through the imaging obtained by its scan. For these reasons, this acrylic model is the perfect measurement and can be compared with the patients’ exam. With the range of softwares available in the market, they must be validated proving their accuracy and reliability between each other. Some authors17,20 already provided reliable results using Dolphin, and others21 using Mimics; however, the comparison between these two softwares was not done earlier. Some studies8,9,22 compared different softwares and the results corroborate to the results of this pilot study showing no statistically significant differences Craniomaxillofacial Trauma and Reconstruction Vol. 11 No. 4/2018 275 This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. Comparison of Imaging Softwares for Upper Airway Evaluation Comparison of Imaging Softwares for Upper Airway Evaluation dos Santos Trento et al. Fig. 4 Upper airway volume (cm3) according to patient and software. between the softwares. However, further studies are required to confirm the results with a larger number of patients. Conflict of Interests The authors declare there was no conflict of interest. Acknowledgments The authors thank funding agency FAPESP (Foundation for Research Support of Sao Paulo) and the Department of Diagnosis and Surgery, Dental School of Araraquara, UNESP. 8 Burkhard JP, Dietrich AD, Jacobsen C, Roos M, Lübbers HT, 9 10 11 12 References 1 Hatcher DC. Cone beam computed tomography: craniofacial and airway analysis. Dent Clin North Am 2012;56(02):343–357 13 2 Stratemann S, Huang JC, Maki K, Hatcher D, Miller AJ. Three- 3 4 5 6 7 dimensional analysis of the airway with cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2011;140(05): 607–615 Guijarro-Martínez R, Swennen GR. Cone-beam computerized tomography imaging and analysis of the upper airway: a systematic review of the literature. Int J Oral Maxillofac Surg 2011; 40(11):1227–1237 Lenza MG, Lenza MM, Dalstra M, Melsen B, Cattaneo PM. 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