CBCT Image Superimposition for Longitudinal Monitoring of Mandibular Cyst Healing: A Technical Note.

Mandibular cystic lesion is a common disease in cranio-maxillofacial surgery with a high recurrence rate. Regular follow-up, early detection and diagnosis are very important in preventing the relapse and giving an active and effective treatment timely. In clinical, the patients after the surgery will be followed-up for 3 - 24 months, and the cone beam computed tomography (CBCT) images will be collected by the physician to observe the morphological changes of cysts. However, the cystic lesion is a small volume in CBCT images, the observation of the lesions is laborious and it will take a certain amount of time to find and analyze the recovery of the cystic lesion at different period. This paper presents an interactive system for automatically detecting and analyzing the cystic lesions of mandible from CBCT images. Firstly, the system integrated an improved mutual information(MI) based image registration method to register the CBCT images collected at different time. Then, an automatic procedure is designed to detect the lesion area, and the features are calculated for doctors to make a better diagnosis. Experimental results demonstrate that our system performs well and has great potential value in clinical practice.

Purpose: The aim of this retrospective study was to evaluate the outcomes of the decompression of large cystic lesions of the mandible and to analyze the correlation between decompression period and the cone-beam computed tomography (CBCT) volume of initial lesions.Materials and Methods: The retrospective study included 13 patients who underwent decompression due to single cystic lesions. All the cystic lesions were localized in the mandible, between the anterior region and the ramus region. All the lesions recovered completely via decompression alone. Volume of the lesions was measured with CBCT and decompression was conducted with a customized acrylic resin stent inserted in the cystic cavity. Decompression period and initial CBCT volume were compared.Results: Mean age of the patients was 39.85 years, mean decompression periods was 12.38 months, mean follow-up period was 20.15 months, and mean initial CBCT volume was 7076.81 mm3. A positive correlation was found between the volume of the cystic lesions and the decompression period.Conclusion: Decompression can provide useful outcomes in the treatment of large cystic lesions in compatible cases since it provides numerous advantages such as noninvasive surgery, low risk of morbidity and severe complications such as bone fracture and inferior alveolar nerve injury. However, in aggressive cystic lesions such as odontogenic keratocyst and ameloblastoma, subsequent definitive surgery following decompression is recommended.

The superimposition of cone-beam computed tomography (CBCT) images is an essential step to evaluate shape variations of pre and postorthodontic operations due to pose variations and the bony growth. The aim of this paper is to present and discuss the latest accomplishments in voxel-based craniofacial CBCT superimpositions along with structure discriminations. We propose a CBCT superimposition method based on joint embedding of subsets extracted from CBCT images. The subset is defined at local extremes of the first-order difference of Gaussian-smoothed volume images to reduce the data involved in the computation. A rotation-invariant integral operator is proposed as the context-aware textural descriptor of subsets. We cope with subset correspondences by joint embedding with matching identifications in manifolds, which take into account the structure of subsets as a whole to avoid mapping ambiguities. Once given subset correspondences, the rigid transformations, as well as the superimposition of volume images, are obtained. Our system allows users to specify the structure-of-interest based on a semisupervised label propagation technique. The performance of the proposed method is evaluated on ten pairs of pre and postoperative CBCT images of adult patients and ten pairs of growing patients, respectively. The experiments demonstrate that the craniofacial CBCT superimposition can be performed effectively, and outperform state of the arts. The integration of sparse subsets with context-aware spherical intensity integral descriptors and correspondence establishment by joint embedding enables the reliable and efficient CBCT superimposition. The potential of CBCT superimposition techniques discussed in this paper is highlighted and related challenges are addressed.

Superimposition of serial Cone Beam Computed Tomography (CBCT) scans has become a valuable tool for three dimensional (3D) assessment of treatment effects and stability. Voxel based image registration is a newly developed semi-automated technique for superimposition and comparison of two CBCT scans. The accuracy and reproducibility of CBCT superimposition on the anterior cranial base or the zygomatic arches using voxel based image registration was tested in this study. 16 pairs of 3D CBCT models were constructed from pre and post treatment CBCT scans of 16 adult dysgnathic patients. Each pair was registered on the anterior cranial base three times and on the left zygomatic arch twice. Following each superimposition, the mean absolute distances between the 2 models were calculated at 4 regions: anterior cranial base, forehead, left and right zygomatic arches. The mean distances between the models ranged from 0.2 to 0.37 mm (SD 0.08–0.16) for the anterior cranial base registration and from 0.2 to 0.45 mm (SD 0.09–0.27) for the zygomatic arch registration. The mean differences between the two registration zones ranged between 0.12 to 0.19 mm at the 4 regions. Voxel based image registration on both zones could be considered as an accurate and a reproducible method for CBCT superimposition. The left zygomatic arch could be used as a stable structure for the superimposition of smaller field of view CBCT scans where the anterior cranial base is not visible.

Several factors influence the condition of the periapical tissues associated with root filled teeth. The primary objective of this study was to retrospectively evaluate the extent and speed of bone healing of large periapical lesions associated with nonsurgical root canal treatment or retreatment. The secondary objective was to analyse the relationship between the time to complete healing when analysed using cone beam computed tomography (CBCT) and other possible predictors that affect healing. Seventy-nine patients were treated during the years 2013-2020 with large periapical lesions of endodontic origin (10-15 mm) as observed on intraoral periapical radiographs (IOPAR) were included. IOPAR and CBCT were available before treatment and during the follow-up (IOPAR every 6 months and CBCT every 12 months). The volume of periapical lesions was calculated by OsiriX Lite software. Variables such as initial volume of the lesion, age, gender, type of treatment or type of root canal filling were compared to identify the differences between healed and unhealed lesions. Pearson's Chi-square test was used for categorical variables, the t-test for age and the Wilcoxon test for initial volume of the lesion. The association between time to healing and the variables was assessed using univariate analysis and multivariate analysis. The Wilcoxon test was used to observe the association of healing time with categorical variables and the correlation index was measured with the quantitative variables. Of the 79 cases analysed, 60 lesions (76%) were completely healed as verified by CBCT in a mean healing time of 19 months, of which 60% healed fully between 12 and 18 months. Increase in age of patient and larger initial volume of the lesion were associated with a significantly longer healing time (p < .001). Gender, filling material and type of treatment did not have a significant effect on the healing process (p > .05). Clinicians should be aware that periapical lesions in older patients and larger areas of bone loss take longer to heal. CBCT monitoring of large periapical lesions is critical and it can help clinicians in the decision-making process.

To evaluate a method of creating three-dimensional representations of mandibular cysts on the cone beam computed tomography (CBCT) data and the data obtained following the evaluation according to Archimede�s principle. A total of 10 mandible with different bone defects miming cysts took part in this study. CBCT scans were obtained from all mandibles and saved in the Digital Imaging and Communications in Medicine (DICOM) format. Data were analysed by two observers: a general dentist and a maxillofacial surgeon. The accuracy of the two methods in assessing cyst volume was compared. There are no major differences between the analysis performed on CBCT data and the real volume of the simulated cystic lesions. Also, there were found differences between the observers. Our results demonstrated the rehabilitee of CBCT scans and volume evaluation of the bone defects. In addition, this study may improve surgical planning and outcomes by knowing the exact volume of grafting material needed prior to the surgical intervention.

To evaluate the feasibility and accuracy of using cone beam CT (CBCT) scans obtained in radiation studies using the small-animal radiation research platform to perform semi-automatic tumour segmentation of pre-clinical tumour volumes. Volume measurements were evaluated for different anatomical tumour sites, the flank, thigh and dorsum of the hind foot, for a variety of tumour cell lines. The estimated tumour volumes from CBCT and manual calliper measurements using different volume equations were compared with the "gold standard", measured by weighing the tumours following euthanasia and tumour resection. The correlation between tumour volumes estimated with the different methods, compared with the gold standard, was estimated by the Spearman's rank correlation coefficient, root-mean-square deviation and the coefficient of determination. The semi-automatic CBCT volume segmentation performed favourably compared with manual calliper measures for flank tumours ≤2 cm(3) and thigh tumours ≤1 cm(3). For tumours >2 cm(3) or foot tumours, the CBCT method was not able to accurately segment the tumour volumes and manual calliper measures were superior. We demonstrated that tumour volumes of flank and thigh tumours, obtained as a part of radiation studies using image-guided small-animal irradiators, can be estimated more efficiently and accurately using semi-automatic segmentation from CBCT scans. This is the first study evaluating tumour volume assessment of pre-clinical subcutaneous tumours in different anatomical sites using on-board CBCT imaging. We also compared the accuracy of the CBCT method to manual calliper measures, using various volume calculation equations.

To test the ability of periapical radiography (PA) and cone-beam computed tomography (CBCT) to determine the presence/absence of periapical lesions and examine the reliability of volumetric measurements of periapical lesions on CBCT scans. After tooth extractions in human mandibles, bone defects were cut at the base of extraction sockets to mimic periapical bone lesions. The teeth were then returned into the extraction sockets. Sixty-three roots of anterior teeth, premolars and molars with artificial periapical lesions and 37 roots without lesions were examined with PA and CBCT. Presence/absence of periapical lesion was noted. The CBCT-based volume of each lesion (Vct) was measured using Amira software 5.4 (Visage Imaging GmbH, Berlin, Germany). A replica of each lesion was created using silicone impression material, and the volume of the replica was measured using a water displacement method, representing the physical volume of the lesion (Vp). Regression analysis was used to test the correlation between the Vp and Vct values. The positive and negative predictive values and accuracy for CBCT in diagnosing periapical lesions were all 1, compared with 1, 0.64 and 0.79 for PA diagnosis. Twenty-one (33%) lesions were undetected by PA. The Vp (21.5 ± 11.0 mm(3) ) and Vct (21.4 ± 11.5 mm(3) ) values of 63 lesions were highly correlated (R(2) = 96.9%, P < 0.001). Cone-beam computed tomography is more accurate than PA in diagnosing periapical lesions associated with mandibular teeth. The volumes of artificial mandibular periapical lesions were accurately measured with CBCT data.

Accuracy of small and medium field of view CBCT in differentiation between periapical cystic and solid lesions

1:36 PM, Abstract No. 120 - Multimodality 3D tumor segmentation in HCC patients treated with TACE

ObjectivesThe aim of this study was to evaluate the effects of manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), and laser-activated irrigation (shock wave-enhanced emission photoacoustic streaming (SWEEPS)) on the periapical healing of large periapical lesions following nonsurgical root canal treatment.Materials and methodsA total of fifty-six systemically healthy patients with a mandibular single-rooted tooth with periapical lesions of endodontic origin and a periapical index score of 3 or higher were included in the study. Before the treatment procedures, lesion volumes were determined volumetrically using cone–beam computed tomography (CBCT). Patients were randomized into treatment (MDA, PUI, SWEEPS) and control groups (n = 14). Root canal treatment and irrigation procedures were performed by a calibrated postgraduate operator and completed at one visit. For routine follow-up, clinical and radiographic evaluations were performed by a blinded evaluator using periapical (PA) radiographs according to Molven’s criteria at 3, 6, and 9 months. At 12 months, lesion volumes were quantified volumetrically using CBCT (ITK-SNAP). The data were statistically analyzed with the Wilcoxon test. The significance level was set at p < 0.05.ResultsIn all groups, the mean lesion volume after treatment was significantly smaller than the mean volume before treatment (p = 0.001). Among the 56 teeth, 11 teeth were ‘totally healed’, and 39 teeth were ‘reduced’ on PA radiographs. No ‘enlargement’ was detected in any group. On CBCT, the lesion volume decreased in the following order: LAI-SWEEPS (86.9%) > PUI (85.4%) > MDA (80.4%) > control (74.5%), with no statistically significant difference (p > 0.05).ConclusionsDespite the limitations of the present study, although a greater percentage of healing was observed in the LAI-SWEEPS and PUI groups, irrigation procedures had no statistically significant effect on the healing of periapical lesions with a single root canal at the 12-month follow-up. On the other hand, the outcome may change in multirooted teeth with curved and complex root canal systems.Clinical relevanceIn the short term and in single-canal teeth, advanced irrigation agitation methods such as laser and ultrasonic did not make a difference in healing other than manual irrigation agitation.

This study assesses whether variations to cone-beam computed tomography (CBCT) slice thickness (ST) effect the detection accuracy and volume assessment of periapical lesions. Forty periapical lesions were assessed on CBCT reconstructions with 0.125-mm, 0.25-mm, 0.50-mm, 1.00-mm, 1.50-mm, and 2.00-mm ST. Mimics Research was used to perform the semi-automatic segmentation technique to determine periapical lesion volume and CBCT periapical volume index (CBCTPAVI) score on each CBCT reconstruction. Diagnostic accuracy was assessed by determining the percentage of lesions detected on each reconstruction, and the Friedman test was conducted to assess for significant differences in lesion volume between the different CBCT reconstructions. Differences among CBCTPAVI scores were also assessed. Periapical lesion volume was significantly underestimated on CBCT reconstructions with ST above 1.00 mm. Variations in periapical lesion volume were the greatest among smaller lesions resulting in false negative diagnoses with the utilization of CBCTs with ST above 0.50 mm. Variations in CBCT ST can significantly influence measured periapical lesion volume, and failure to account for this may lead to misinterpretation of lesion progression or healing. A minimum ST of 0.50 mm was required for the reliable detection of all periapical lesions, and this threshold serves as a benchmark for optimizing CBCT acquisition protocols to preserve diagnostic accuracy while minimizing radiation exposure.

By integrating digital models with cone beam computed tomography (CBCT) images and registration on stable hard tissue regions for superimposition, we aimed to enable a more precise and detailed analysis of Invisalign treatment on Class III malocclusion. Digital models of 12 Class III adults at pretreatment (T1) and posttreatment (T2) were integrated with maxillofacial CBCT images. The T1 and T2 CBCT images were superimposed using voxel-based registration of stable cranial base structures to assess the three-dimensional movement of the maxillary teeth and positional changes of the mandible. Mandibular tooth movement was evaluated by superimposition of the mandibular CBCT images, registered on the symphysis and mandibular body. The virtual planning model created by ClinCheck was superimposed based on its position relative to the T1 digital model. The median accuracy of distal movement for the mandibular first molar cusps ranged from 26.72% to 33.87%. With miniscrew anchorage, the accuracy ranged from 39.28% to 44.66%. Actual distal movement averaged 0.62 ± 0.82 mm to 0.80 ± 0.89 mm with Class III elastics, and 2.02 ± 1.71 mm to 2.29 ± 1.53 mm with miniscrews. The maxillary incisors significantly proclined more with Class III elastic traction. No significant positional changes in mandibular anatomical landmarks were observed during treatment with miniscrew anchorage, whereas the use of Class III elastics led to significant positional changes in the condyle head. Invisalign treatment may not reach the expected efficacy in mandibular dentition distalisation, especially when skeletal anchorage is absent.

Computer aided implantology is the safest way to perform dental implants. The research of high accuracy represents a daily effort. The validated method to assess the accuracy of placed dental implants is the superimposition of a pre-operative and a post-operative cone beam computed tomography (CBCT) with planned and placed implants. This procedure is accountable for a biologic cost for the patient. To investigate alternative procedure for accuracy assessment, fifteen resin casts were printed. For each model, six implants were digitally planned and then placed following three different approaches: (a) template guided free hand, (b) static computer aided implantology (SCAI), and (c) dynamic computer aided implantology (DCAI). The placement accuracy of each implant was performed via two methods: the CBCT comparison described above and a matching between implant positions recovered from the original surgical plan with those obtained with a post-operative intraoral scan (IOS). Statistically significant mean differences between guided groups (SCAI and DCAI) and the free hand group were found at all considered deviations, while no differences resulted between the SCAI and DCAI approaches. Moreover, no mean statistically significant differences were found between CBCT and IOS assessment, confirming the validity of this new method.

To determine if small and medium field of view (FOV) cone beam computed tomography (CBCT) adjusted grey density values can be used to distinguish between periapical cystic and solid lesions. Fifty-seven patients with periapical lesions having retrievable small or medium FOV CBCT images and biopsy samples were included. Two oral and maxillofacial pathologists examined the biopsy samples to provide the gold standard diagnosis of cystic or solid lesion. From the CBCT images, two independent examiners recorded the minimum adjusted grey density value of each lesion twice. Intra-examiner and inter-examiner reliability of the measurements were analysed, and sensitivity, specificity and accuracy of the minimum grey values in distinguishing a solid from cystic lesion were calculated. A receiver operating curve for diagnostic ability of adjusted grey density values to differentiate between periapical cystic and solid lesions was obtained, and the area under the curve (AUC) was calculated. The intra- and inter-examiner reliability of the grey density values of the lesions and dentine were excellent. The AUC was 0.44 (P-value=0.45). The adjusted grey density value with the greatest accuracy for differentiating between cystic and solid lesions had an accuracy, sensitivity and specificity of 0.54, 1.00 and 0.075, respectively. Small FOV CBCT adjusted grey density values obtained by the device used in the study could not distinguish between periapical cystic and solid lesions. Further developments in CBCT devices are needed to improve the accuracy of grey density measurements.