Multiplanar Reconstruction Views Research Articles

Maxillary and upper airway changes immediately after mini-screw assisted rapid maxillary expansion in class Ⅲ patients

Objective: To assess maxillary sagittal and vertical as well as upper airway changes immediately after mini-screw assisted rapid maxillary expansion (MARME) in class Ⅲ patients. Method: A consecutive sample of 48 class Ⅲ patients with maxillary transverse deficiency who visited the Department of Orthodontics, School & Hospital of Stomatology, Wuhan University between January 2013 and March 2023 was retrospectively collected. The sample was comprised of 24 growing patients (cervical vertebra maturation, CVM 1-4) and 24 nongrowing patients (CVM 5-6). Cone-beam CT scans before (T0) and immediately after MARME (T1) were imported into Dolphin Imaging software, and then voxel-based superimposition was conducted on the basis of the anterior cranial base. Sagittal and vertical changes of the maxillary landmarks (A, ANS, PNS, UI and Spr), as well as upper airway changes after MARME were measured on multiplanar reconstruction views. Wilcoxon signed-rank test was employed to analyze the changes after MARME. Mann-Whitney U test was employed to compare the changes between growing and non-growing patients. Results: Some class Ⅲ patients exhibited significant maxillary sagittal and vertical changes immediately after MARME. The amount of changes in midpalatal suture was 4.03 (2.99, 4.87) mm in growing patients, significantly larger than that in non-growing patients [2.27 (1.49, 3.64) mm] (U=3.18, P=0.001). In growing class Ⅲ patients, the forward changes of A, ANS, PNS, UI and Spr were 0.35 (0.06, 0.80), 0.48 (0.11, 0.88), 0.48 (0.13, 0.99), 0.53 (-0.33, 1.04) and 0.40 (0.03, 0.69) mm, respectively. Vertically, the downward changes of A, ANS, PNS, UI and Spr were 1.45 (0.99, 2.13), 1.18 (0.61, 1.95), 1.30 (0.91, 1.96), 1.20 (0.71, 1.83) and 1.30 (0.81, 1.73) mm, respectively. All changes were significantly different from 0 after treatment (P<0.05). In nongrowing patients, PNS moved forward by 0.18 (-0.08, 0.39) mm while other sagittal changes were statistically insignificant (P>0.05); vertically, the downward changes of A, ANS, PNS, UI and Spr were 0.90 (0.51, 1.39), 0.73 (0.41, 1.21), 0.70 (0.55, 1.08), 0.60 (0.36, 1.19) and 0.70 (0.55, 1.23) mm, respectively. Significant immediate increase of the nasopharynx volume and nasal width was obtained in both groups (P<0.05), and the changes of oropharynx volume and minimum cross-sectional area (MCA) presented as statistically insignificant (P>0.05). Conclusions: For growing class Ⅲ patients, besides transverse expansion, significant forward and downward changes of maxilla were obtained immediately after MARME. For non-growing patients, significant downward changes were observed, while sagittal changes were negligible. The nasopharynx volume increased in both growing and nongrowing class Ⅲ patients immediately after MARME, whereas, the changes of oropharynx volume and MCA presented as statistically insignificant.

Pixel gray measurement for the diagnosis of dental ankylosis in cone beam computed tomography images

The aim of this study was to investigate dental ankylosis in unerupted or partially erupted teeth by using cone beam computed tomography (CBCT) to quantify pixel intensity. In total, 157 CBCT images from individuals with a total of 206 unerupted or partially erupted teeth with suspected ankylosis were evaluated. CBCT images were analyzed for the presence of ankylosis by 2 oral radiologists by quantifying mean pixel intensities (analysis 1) and variations in pixel intensities (analysis 2) in normal and ankylosed regions. The association between ankylosis and demographic and tooth-related factors was also examined. Ankylosis was diagnosed in 57 teeth (27.7%). The diagnosis was established with all 3 multiplanar reconstruction views in 22 of these teeth (38.6%). In analysis 1, a higher pixel intensity was observed in areas with ankylosis compared with normal periodontal ligament (PDL) density as a result of bone deposition in this region, which is characteristic of ankylosis (P < .001). In analysis 2, reductions in pixel intensity were greater in the PDL areas than in the ankylosed areas. Ankylosis was significantly associated with the anterior teeth, the maxillary arch, single-rooted teeth, and impacted teeth (P ≤ .026). Our results suggest that CBCT measurement of pixel intensity may be useful for the diagnosis of ankylosis.

Diagnostic Potential of Panoramic Radiography and CBCT in Detecting Implant-Related Ex Vivo Injuries of the Inferior Alveolar Canal Border.

The aim of this ex vivo study was to compare the diagnostic performances of panoramic radiography and cone beam computerized tomography (CBCT) in detecting implant-related injuries of the inferior alveolar canal. Monocortical bone windows were created in 60 fresh sheep hemimandibles, the inferior alveolar canals were revealed and 120 dental implants were inserted. Three types of injuries, described as pilot drill damage (PDRILL), collapsing of the superior border of the canal (COLL), penetration of the implant tip into the canal (PENET) and one control group, were simulated. Standard (PANO) and dentition mode panoramic (PANO-DENT) images as well as CBCT data presented as multiplanar reconstruction (MPR) and cross-sectional (CROSS) views were evaluated by 6 observers who had also expressed their level of confidence to their final diagnosis. Intra- and interobserver agreement scores were rated good. The area under the curve (AUC) values and the confidence scores for CROSS and multiplanar reformation (MPR) views were both significantly higher than those of PANO and PANO-DENT (P < .05 for each) in PDRILL group. In COLL group, observers showed less confidence to PANO and PANO-DENT compared to CROSS and MPR techniques (P < .05 for each). No other significant differences were found. Within the limits of this experimental study, it can be suggested that the standard and dentition modes of panoramic radiography can be as effective as CBCT in the detection of penetrating and collapsing injuries, but multiplanar and cross-sectional views of the CBCT are more accurate than panoramic radiography in the detection of pilot drill injuries in sheep mandible.

Computed Tomographic Osteolytic Analysis of a First-Generation Remelted Highly Cross-Linked Polyethylene in Total Hip Arthroplasty—At a Minimum of 15-Year Follow-Up

BackgroundLow polyethylene wear rate and low incidence of osteolysis have been reported after total hip arthroplasty (THA) using first-generation remelted highly cross-linked polyethylene (HXLPE). However, osteolysis has not been evaluated in long-term studies of these patients (15 years or more). The present study assessed computed tomography (CT) images to determine the incidence of osteolysis associated with HXLPE in THA during at least 15 years of follow-up. MethodsWe evaluated 105 primary THAs in 84 patients (77 women and 7 men). Mean follow-up was 15.9 years (range, 15-18 years). All THAs used a Longevity HXLPE liner and a 26-mm zirconia femoral head. Areas of osteolysis were identified from CT images using 3D and multiplanar reconstruction views. ResultsCT 3D multiplanar reconstruction images at 15-year follow-up showed no obvious osteolysis in the acetabulum or femur of any patient. No patients developed cup loosening or liner breakage. ConclusionOur study indicates that first-generation remelted HXLPE liners do not increase the risk of osteolysis during 15-year follow-up and suggests that the wear particles from first-generation remelted HXLPE are less biologically active than those generated by conventional polyethylene devices.

Computed tomographic morphometry of the biceps brachii muscle tendon of dogs affected by the medial coronoid disease.

The objective of this study was to measure the biceps brachii muscle (BBM) attachment to the medial coronoid process (MCP) using computed tomography images and to compare these data between clinically healthy and dogs affected by medial coronoid disease (MCD). Computed tomography was performed in MCD-affected and healthy dogs. Multiplanar reconstruction views were obtained to measure distance (cm) of the BBM attachment point to the MCP. Results showed that the mean BBM attachment point-to-MCP was 1.42±0.23cm in MCD-affected and 1.27±0.20cm in healthy dogs, respectively. In dogs with MCD, the BBM attachment point-to-MCP was significantly more abaxial than in clinically healthy dogs (p<.001). The results of this study support the hypothesis that the BBM attachment site is more abaxial to the MCP and therefore may contribute to supraphysiological overload leading to MCD. Albeit more research is necessary, this study proves a relationship between the BBM attachment point and the development of MCD.

A New, Easy, Fast, and Reliable Method to Correctly Classify Acetabular Fractures According to the Letournel System.

Background:Accurate classification of acetabular fractures remains difficult. To aid in the classification of acetabular fractures and to aid in teaching, our department developed a diagnostic algorithm that involves the use of 1 standardized 3-dimensional reconstruction of a computed tomography (CT) scan (an exopelvic view without the femoral head) with 8 anatomical landmarks. The algorithm was integrated into a smartphone application (app). The main objective of this study was to test the efficacy of this algorithm and smartphone app.Methods:Fourteen reviewers (3 experts, 3 fellows, 3 residents, and 5 novice reviewers) evaluated a set of 35 CT scans of acetabular fractures in 2 phases. During the first phase, the scans (including axial 2-dimensional views and 3-dimensional (3D) multiplanar reconstruction views) were assessed by each reviewer twice, with an interval of 4 weeks between the readings to decrease recall bias. During that phase, the reviewers were provided with a diagram of the Letournel classification system with no guidelines for interpretation. During the second phase, performed 4 weeks after the first phase, 1 standardized 3D reconstruction (an exopelvic view without the femoral head) was reviewed twice, with an interval of 4 weeks between the readings. During that phase, the reviewers used the smartphone app. The primary outcome was the accuracy of classification. Interobserver reliability, reading time, and time needed for accurate classification were noted.Results:The accuracy of fracture classification was 64.5% when the standard method of analysis was used and 83.4% when the app was used (p < 0.001). Improvement was noted in all groups, with the expert group showing the least improvement (88.6% to 97.2%, p = 0.04) and the novice group showing the most improvement (42.0% to 75.5%, p < 0.001). Furthermore, use of the app greatly increased the accuracy of classification of complex fractures. The average reading time was 71.8 minutes when the standard method was used and 37.4 minutes when the app was used. The interobserver reliability improved in all groups to an excellent reliability (interclass correlation coefficient [ICC] > 0.79).Conclusions:The Letournel classification system is difficult to understand and to learn but remains the only system guiding the surgical strategy for acetabular fractures. The impact of diagnostic algorithms is debatable. The most important finding of the present study is the high accuracy for inexperienced groups when the app was used. Another important finding is the high reliability of this method for the diagnosis of complex acetabular fractures.

Comprehensive Two-Dimensional Interrogation of the Tricuspid Valve Using Knowledge Derived from Three-Dimensional Echocardiography

Accurate identification of tricuspid valve (TV) leaflets by two-dimensional (2D) transthoracic echocardiography is difficult because of variability in the intersection between the imaging plane and leaflets. Using information obtained from multiplanar reconstruction (MPR) of three-dimensional (3D) data sets, the investigators sought to define "novel" 2D views that would allow targeted interrogation of TV leaflets using 2D transthoracic echocardiography. Images of the TV in the standard 2D views (apical four chamber, right ventricular focused, right ventricular inflow, and parasternal short axis) and 3D data sets were acquired from the same probe position in 106 adults. Three-dimensional MPR was used to determine which leaflet combination was seen in the 2D image: anterior and septal, anterior and posterior, anterior alone, or posterior and septal. Using this analysis, 2D landmarks were identified to define nonstandard TV views tailored to depict specific leaflets. Two-dimensional images in these views and 3D data sets were then prospectively collected in 54 additional patients. Three independent readers analyzed these 2D views to determine TV leaflet combinations, and their interpretation was compared with 3D MPR-derived reference. Three-dimensional MPR views made it possible to define six nonstandard 2D views on the basis of anatomic clues and landmarks, which consistently depicted all the aforementioned leaflet combinations. When these six views were prospectively tested, the agreement of TV leaflet identification against 3D MPR was excellent (κ = 0.88, κ = 0.93, and κ = 0.98). The nonstandard 2D views defined in this study allow accurate TV leaflet identification and may thus be useful when localization of TV leaflet pathology is clinically important.

Virtual Endoscopy to Plan Transtympanic Approach to Labyrinthine Windows.

The aim of this study was to evaluate the position and the accessibility of labyrinthine windows through the external auditory canal (EAC) by virtual endoscopy based on computed tomographic scan images. Prospective cross-sectional study. Tertiary referral center. Sixty-three high-resolution temporal bone computed tomographic scans were obtained from 34 adult patients undergoing various otologic procedures. Images were analyzed by the virtual endoscopy function included in Osirix (www.osirix-viewer.com). The endoscope was constrained in the EAC. The visible surfaces of target anatomic structures were assessed on multiplanar reconstruction views. The optimal angles of the virtual endoscope position showed a relatively high interindividual variability in the axial plane (64 ± 2.4 degrees for the oval window [OW] and 60 ± 2.5 degrees for the round window [RW]) position, but a low interindividual variation was noted in the coronal plane (107 ± 1.5 degrees for the OW and 112 ± 1.7 degrees for the RW). The RW was accessible in 87% of cases. The OW accessibility could be staged as follows: 1, invisible stapedial superstructure (10% of cases); 2, stapedial posterior crus partly visible (33%); 3, entire posterior crus and pyramid visible (44%); 4, posterior and anterior crus visible (13%). Virtual endoscopy through the EAC can evaluate the accessibility of the OW or RW via a transcanal route. This technique seems to be helpful in preplanning minimally invasive procedures by this approach such as cochlear implantation.

Single-beat real-time three-dimensional echocardiographic automated contour detection for quantification of left ventricular volumes and systolic function

To assess the feasibility and accuracy in measuring left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) with Siemens single-beat real-time 3D transthoracic echocardiography. The LV volumes and EF were measured in 3D datasets acquired by six imaging modes (time-1-harmonic (T1H), time-1-fundamental, time-2-harmonic, time-2-fundamental, space-1-harmonic (S1H), and space-1-fundamental) in 41 patients using the automated contouring algorithm and compared with manually corrected 3DE QLAB measurements. The main determinates of the temporal and spatial resolutions of 3D datasets acquired were the fundamental and harmonic modes. Consequently, the S1H mode had the lowest volume rate and highest spatial resolution. Compared with the 3DE QLAB analysis, the S1H mode resulted in the best LV volumes and EF estimates in all patients (0 ± 10 % for EF, -7 ± 44 ml for EDV, -7 ± 39 ml for ESV) and in the 10 patients with correct LV contour tracking according to a visual assessment from the multiplanar reconstruction views in all six modes (0 ± 9 % for EF, -3 ± 23 ml for EDV, -2 ± 14 ml for ESV). The T1H mode was the best alternative. Overall 28 patients (68 %) could be analysed automatically and satisfyingly with the S1H and T1H modes: 0 ± 8 % (EF), 0 ± 27 ml (EDV) and -1 ± 16 ml (ESV). The accuracy of the Siemens automated RT-3D algorithm in measuring LV volumes and EF is significantly influenced by the different imaging modes. The S1H mode may be the preferred 3D acquisition mode, supplemented by the T1H mode in enlarged LVs that do not fit in the S1H acquisition sector.

Polyp Volume Versus Linear Size Measurements at CT Colonography: Implications for Noninvasive Surveillance of Unresected Colorectal Lesions

Proposed surveillance of unresected medium-sized (6.0-9.9 mm) polyps will require reliable detection of small incremental changes. The purpose of this study was to assess the reproducibility of linear versus volume measurements of polyp size at CT colonography (CTC) and to correlate results with a hemispheric model. The study group consisted of 30 polyps on supine and prone CTC data sets. Measurements were performed separately by two experienced radiologists using the same CTC system (Vitrea 2), resulting in 120 linear and volume measurements. Linear size was defined as the longest dimension among the 2D multiplanar reconstruction views. Semiautomated volume determination required manual tracing of polyp boundaries on 2D multiplanar reconstruction views. The relative error between reviewers 1 and 2 was defined as 100 x (/D1 - D2/)/D(ave) for linear size (D) and as 100 x (/V1 - V2)/V(ave) for volume (V), where ave is average. The mean relative error for linear size and volume measurement was 10.4% +/- 10.7% and 16.9% +/- 13.2%, respectively. Median linear size and volume of polyps were 9.4 mm and 270 mm3, respectively. CTC-derived volumes for medium-sized polyps closely approximated hemispheric volume (V = (pi/12) x D(b), where b =3.13, r2 = 0.90). Small incremental changes in hemispheric size result in a 3:1 relative change in volume versus diameter, such that a 1-mm diameter change in a medium-sized hemispheric polyp results in a relative change in linear size and volume ranging from approximately 11-18% and 31-53%, respectively. Because changes in polyp volume are amplified compared with linear dimension, volume measurement rather than diameter measurement will better allow detection of small incremental changes in polyp size using CTC.