Multiplanar Imaging Research Articles

Intraoperative 3-dimensional imaging (O-arm) for assessment of pedicle screw position: Does it prevent unacceptable screw placement?

BackgroundPedicle screws are biomechanically superior over other spinal fixation devices. When improperly positioned, they lose this advantage and put adjacent structures at risk. Accurate placement is therefore critical. Postoperative computed tomography (CT) scans are the imaging gold standard and have shown malposition rates ranging from 2% to 41%. The O-arm (Medtronic Navigation, Louisville, Colorado) is an intraoperative CT scanner that may allow intervention for malpositioned screws while patients are still in the operating room. However, this has not yet been shown in clinical studies. The primary objective of this study was to assess the usefulness of the O-arm for evaluating pedicle screw position by answering the following question: What is the rate of intraoperative pedicle screw revision brought about by O-arm imaging information? A secondary question was also addressed: What is the rate of unacceptable thoracic and lumbar pedicle screw placement as assessed by intraoperative O-arm imaging? MethodsThis is a case series of consecutive patients who have undergone spine surgery for which an intraoperative 3-dimensional (3D) CT scan was used to assess pedicle screw position. The study comprised 602 pedicle screws (235 thoracic and 367 lumbar/sacral) placed in 76 patients, and intraoperative 3D (O-arm) imaging was obtained to assess screw position. Action taken at the time of surgery based on imaging information was noted. An independent review of all scans was also conducted, and all screws were graded as either optimal (no breach), acceptable (breach ≤2 mm), or unacceptable (breach >2 mm). The rate of pedicle screw revision, as detected by intraoperative 3D CT scan, was determined. ResultsOn the basis of 3D imaging information, 17 of 602 screws (2.8%) in 14 of 76 cases (18.4%) were revised at the time of surgery. On independent review of multiplanar images, 11 screws (1.8%) were found to be unacceptable, 32 (5.3%) were acceptable, and 559 (92.9%) were optimal. All unacceptable screws were revised to an optimal or acceptable position, and an additional 6 acceptable screws were revised to an optimal position. Thus, by the end of the cases, none of the 602 pedicle screws in the 76 surgical procedures was in an unacceptable position. ConclusionThe new-generation intraoperative 3D imaging system (O-arm) is a useful tool that allows more accurate assessment of pedicle screw position than plain radiographs or fluoroscopy alone. It prompted intraoperative repositioning of 2.8% of pedicle screws in our series. Most importantly, it allowed identification and revision of all unacceptably placed pedicle screws without the need for reoperation.

High-resolution MRI demonstrates detailed anatomy of the axillary brachial plexus. A pilot study

Axillary block is the most commonly performed brachial plexus block and may be guided by nerve stimulation or ultrasound. Magnetic resonance imaging (MRI) has proven to be beneficial in presenting anatomy of interest for regional anaesthesia and in demonstrating spread of local anaesthetic. The aim of this pilot study was to demonstrate the anatomy as shown by MRI of the brachial plexus in the axillary region. Nine volunteers and nine patients were examined in a 3.0 Tesla MR. The patients had two different brachial plexus blocks. Subsequently, they were scanned by MRI and finally tested clinically for block efficacy before operation. Axial images, with and without local anaesthetics injected, were viewed in a sequence loop to identify the anatomy. With the high-resolution MRI, we obtained images of good quality, and cords and all terminal nerves could be identified. When local anaesthetics are injected, neurovascular structures are displaced, and the vein is compressed. Viewing the images in a sequence loop facilitates identification of the different nerves and has high instructive value (links S1-3 to these loops are enclosed). Clinical high-field 3.0 Tesla MRI scanner gives good visualization of brachial plexus in the axilla. The superior ability to detect local anaesthetics after it has been injected and the multiplanar imaging capability make MRI a useful tool in studies of the brachial plexus.

Abstract 251: Semiautomated Measurement of Ascending Aortic Aneurysm Versus Manual Measurement: Assessment of Variability

Purpose: To evaluate inter method and intra observer variability of a novel semi-automated method for measurement of ascending aorta aneurysm (AAA) in ECG gated dual source CT angiogram (DSCTA). Material and Method: Under an IRB approved protocol, multiplanar reformatted images of 40 patients with AAA were measured in DSCTA images. Transaxial maximum diameter of inner wall to inner wall was measured at five anatomic locations of thoracic aorta: annulus, sinus, sinotubular junction (STJ), mid ascending aorta at the level of right pulmonary artery (MAA), and proximal aortic arch immediately proximal to innominate artery (PROX) (Figure 1). Measurements were performed by conventional manual method and the novel semi-automated segmentation software and compared. Inter method and intra observer variability were evaluated according to Intra Class Correlation (ICC). Time required for post processing of the aorta with both methods was recorded in all the cases. Results: Mean maximum diameters in semi-automated method were: annulus 31.10 mm, sinus: 41.95 mm, STJ: 38.05 mm, MAA: 41.88 mm, and PROX: 37.60 mm. Manual method showed mean maximum diameter of 30.87 mm, 42.05 mm, 36.87 mm, 41.18 mm, and 36.42 mm at annulus, sinus, STJ, MAA, and PROX, respectively. There was an excellent inter method and intra observer agreement between two methods at all five points (ICC > 0.9). The post processing time was 8’2’’±1’35” for the semi-automated method while this time was 19’± 20” for the manual method. Conclusion: The novel semi-automated tool demonstrated an excellent agreement with conventional manual method in measurement of AAA in ECG gated DSCTA with the advantage of significant reduction in the post processing time.

Sectional Anatomy Aid for Improvement of Decompression Surgery Approach to Vertical Segment of Facial Nerve

The aim of this study was to find a surgical approach to a vertical segment of the facial nerve (VFN) with a relatively wide visual field and small lesion by studying the location and structure of VFN with cross-sectional anatomy. High-resolution spiral computed tomographic multiplane reformation was used to reform images that were parallel to the Frankfort horizontal plane. To locate the VFN, we measured the distances as follows: from the VFN to the paries posterior bony external acoustic meatus on 5 typical multiplane reformation images, to the promontorium tympani and the root of the tympanic ring on 2 typical images. The mean distances from the VFN to the paries posterior bony external acoustic meatus are as follows: 4.47 mm on images showing the top of the external acoustic meatus, 4.20 mm on images with the best view of the window niche, 3.35 mm on images that show the widest external acoustic meatus, 4.22 mm on images with the inferior margin of the sulcus tympanicus, and 5.49 mm on images that show the bottom of the external acoustic meatus. The VFN is approximately 4.20 mm lateral to the promontorium tympani on images with the best view of the window niche and 4.12 mm lateral to the root of the tympanic ring on images with the inferior margin of the sulcus tympanicus. The other results indicate that the area and depth of the surgical wound from the improved approach would be much smaller than that from the typical approach. The surgical approach to the horizontal segment of the facial nerve through the external acoustic meatus and the tympanic cavity could be improved by grinding off the external acoustic meatus to show the VFN. The VFN can be found by taking the promontorium tympani and tympanic ring as references. This improvement is of high potential to expand the visual field to the facial nerve, remarkably without significant injury to the patients compared with the typical approach through the mastoid process.

Posterior vaginal prolapse shape and position changes at maximal Valsalva seen in 3-D MRI-based models

Two-dimensional magnetic resonance imaging (MRI) of posterior vaginal prolapse has been studied. However, the three-dimensional (3-D) mechanisms causing such prolapse remain poorly understood. This discovery project was undertaken to identify the different 3-D characteristics of models of rectocele-type posterior vaginal prolapse (PVP(R)) in women. Ten women with (cases) and ten without (controls) PVP(R) were selected from an ongoing case-control study. Supine, multiplanar MR imaging was performed at rest and maximal Valsalva. Three-dimensional reconstructions of the posterior vaginal wall and pelvic bones were created using 3D Slicer v. 3.4.1. In each slice the posterior vaginal wall and perineal skin were outlined to the anterior margin of the external anal sphincter to include the area of the perineal body. Women with predominant enteroceles or anterior vaginal prolapse were excluded. The case and control groups had similar demographics. In women with PVP(R) two characteristics were consistently visible (10/10): (1) the posterior vaginal wall displayed a folding phenomenon similar to a person beginning to kneel ("kneeling" shape) and (2) a downward displacement in the upper two thirds of the vagina. Also seen in some, but not all of the scans were: (3) forward protrusion of the distal vagina (6/10), (4) perineal descent (5/10), and (5) distal widening in the lower third of the vagina (3/10). Increased folding (kneeling) of the vagina and an overall downward displacement are consistently present in rectocele. Forward protrusion, perineal descent, and distal widening are sometimes seen as well.

Missed rib fractures on evaluation of initial chest CT for trauma patients: pattern analysis and diagnostic value of coronal multiplanar reconstruction images with multidetector row CT

The objective of this study was to review the prevalence and radiological features of rib fractures missed on initial chest CT evaluation, and to examine the diagnostic value of additional coronal images in a large series of trauma patients. 130 patients who presented to an emergency room for blunt chest trauma underwent multidetector row CT of the thorax within the first hour during their stay, and had follow-up CT or bone scans as diagnostic gold standards. Images were evaluated on two separate occasions: once with axial images and once with both axial and coronal images. The detection rates of missed rib fractures were compared between readings using a non-parametric method of clustered data. In the cases of missed rib fractures, the shapes, locations and associated fractures were evaluated. 58 rib fractures were missed with axial images only and 52 were missed with both axial and coronal images (p=0.088). The most common shape of missed rib fractures was buckled (56.9%), and the anterior arc (55.2%) was most commonly involved. 21 (36.2%) missed rib fractures had combined fractures on the same ribs, and 38 (65.5%) were accompanied by fracture on neighbouring ribs. Missed rib fractures are not uncommon, and radiologists should be familiar with buckle fractures, which are frequently missed. Additional coronal imagescan be helpful in the diagnosis of rib fractures that are not seen on axial images.

Oblique approach for CT-guided liver radiofrequency ablation using multiplanar reformation images in hepatocellular carcinoma

To evaluate the feasibility and safety of CT-guided radiofrequency (RF) ablation by caudal-cranial oblique insertion using multiplanar reformation (MPR) images for hepatocellular carcinomas (HCCs). Twenty-two HCCs in 19 patients that were difficult to demonstrate on ultrasound (mean tumor diameter was 17.5 mm) were treated with CT-guided RF ablation by caudal-cranial oblique insertion to avoid pneumothorax, using MPR images after transcatheter arterial chemoembolization. The insertion point and direction of insertion, avoiding aerated lung parenchyma, bones, large vessels, and intestine, were sought on the MPR images. Technical success was defined as complete eradication of tumor enhancement in the contrast-enhanced CT. Local tumor progression was defined by the appearance of enhanced tumor adjacent to the zone of ablation. The technical success rate, local tumor progression, and complications were investigated. The coronal plane was used for insertion in 18 tumors, the sagittal plane in 3 tumors, and the oblique plane in 1 tumor. RF electrode placement was successful and complete necrosis was obtained in all cases. During the mean follow-up period of 38.0 months, local tumor progression was not detected in any of the patients. There were no major complications, including pneumothorax. CT-guided RF ablation by caudal-cranial oblique insertion using MPR images is a feasible and safe therapeutic option.

3D navigation and monitoring for spinal milling operation based on registration between multiplanar fluoroscopy and CT images

Milling operations in spinal surgery demand much experience and skill for the surgeon to perform the procedure safely. A 3D navigation method is introduced aiming at providing a monitoring system with enhanced safety and minimal intraoperative interaction. An automatic registration method is presented to establish the 3D–3D transformation between the preoperative CT images and a common reference system in the surgical space, and an intensity-based similarity metric adapted for the multi-planar configuration is introduced in the registration procedure. A critical region is defined for real-time monitoring in order to prevent penetration of the lamina and avoid violation of nerve structures. The contour of the spinal canal is reconstructed as the critical region, and different levels of warning limits are defined. During the milling procedure, the position of the surgical instrument relative to the critical region is provided with augmented display and audio warnings. Timely alarm is provided for surgeons to prevent surgical failure when the mill approaches the critical region. Our validation experiment shows that real-time 3D navigation and monitoring is advantageous for improving the safety of the milling operation.

Computed tomography colonography for 5 cases of pneumatosis cystoides intestinalis

Computed tomography colonography (CTC) was performed in 5 patients with pneumatosis cystoides intestinalis (PCI). The virtual colonoscopy view of CTC as well as total colonoscopy (TCS) findings showed polypoid lesions in the colon, and multiplanar reconstruction images of the colon revealed in the polypoid lesions of the colon. We confirmed the diagnosis of PCI in all cases. CTC also detected the PCI lesions in the subserosa of the colonic wall which were not detected by TCS. Accurate evaluation of the extent of PCI involvement was obtained by CT air-contrast enema images. CTC is useful for detection of PCI lesions, assessment of the exact site and final diagnosis for PCI.

Analysis of Pelvic Incidence From 3-Dimensional Images of a Normal Population

Pelvic incidence (PI) was measured in 3 dimensions from computed tomographic (CT) images of normal subjects using a computerized method. To obtain the angle of PI from 3-dimensional (3D) images and analyze its distribution in a normal population. The sagittal alignment of the pelvis is usually evaluated in 2-dimensional (2D) sagittal radiographs. The purpose of this study is to measure and analyze PI, which represents a key parameter of sagittal alignment, in 3D images. A computerized method, based on image-processing techniques, was used to automatically determine the anatomical references required to measure PI, that is, the centers of the femoral heads in 3 dimensions and the center and inclination of the sacral end plate in 3 dimensions. Multiplanar image reformation was applied to obtain perfect sagittal views with all anatomical structures completely in line with the hip axis from which PI was calculated. PI was successfully obtained in CT images of 370 normal subjects (mean age: 41.5 years; range: 1-87 years). The mean PI (± standard deviation) was equal to 46.6° (±9.2°) for male subjects, 47.6° (±10.7°) for female subjects, and 47.1° (±10.0°) for both sexes. No statistically significant differences were obtained between the sexes, and statistically significant correlation was obtained between PI and age. In this study, the sagittal alignment of the pelvis was evaluated in terms of PI completely in 3 dimensions. The results show that computerized measurements of PI in 3 dimensions are less variable than manual measurements. The large span of PI values for normal subjects indicates that the natural variation of PI is relatively large.

Right aberrant subclavian artery in a 12‐year old with dysphagia and thoracic outlet syndrome (TOS)

A left aortic arch with aberrant right subclavian artery is the most common congenital aortic arch anomaly.We have demonstrated aberrant right and left subclavian arteries on MRI of the brachial plexus in adults presenting with symptoms of TOS: arm and hand pain with paresthesias; hand muscle weakness, headache; autonomic vascular and temperature changes; whooshing sounds in the ear, ear pressure pain; jaw pain, and visual “floaters”.A 12‐year old girl presented with complaints of problems swallowing solid foods since age seven years. She recently developed pain in the right chest wall with inspiration, in addition to common TOS complaints of headache, dizziness, hand pain, tingling and numbness, muscle pains in the neck and shoulders and back, along with jaw pain and whooshing sounds in the ears.Bilateral MRI/MRA/MRV display venous and neurovascular compression in TOS patients without the use of contrast material. Bilateral multiplanar imaging was conducted on a 1.5 Tesla GE Signa LX (Clin. Anat.1995; 8:1–16), with the field of view modified to include the dural sinuses and demonstrated a right aberrant subclavian artery with a left aortic arch and displacement of the esophagus but no significant tracheal displacement, as seen in adults. Management of these patients will be discussed.

Intimal Tears in Thoracic Aortic Dissection: Appearance on MDCT With Virtual Angioscopy

The location, number, size, and configuration of intimal tears in aortic dissection have important therapeutic and prognostic implications. Planning of procedures to treat complications of aortic dissection may require precise delineation of the intimal tears. The purpose of this article is to illustrate the ability of MDCT using multiplanar image reformatting and virtual angioscopy to depict the location and appearance of intimal tears and fenestrations within dissection flaps in cases of thoracic aortic dissection. MDCT with virtual angioscopy can depict the configuration of intimal tears in cases of thoracic aortic dissection, which may facilitate therapeutic planning.

Ultra–high-field Magnetic Resonance Enterography in the Diagnosis of Ileitis (Neo-)Terminalis

Magnetic resonance (MR) enterography provides the advantages of conventional enteroclysis and those of cross-sectional imaging. Adequate luminal distension, combined with ultrafast sequences, results in excellent delineation of mural and extramural manifestations of Crohn's disease. Recent technical advances, including ultra-high-field strength MR with its capability to provide fast multiplanar images with excellent soft tissue contrast, are only rarely included in abdominal studies. One hundred four consecutive patients with a proved or suspected diagnosis of ileitis terminalis were prospectively selected for MR imaging studies and ileocolonoscopy. The final diagnosis was based on histopathological findings or based on a combined endpoint of clinical, laboratory, endoscopic, and imaging findings. According to the endoscopic examination, stenosis was present in 26 patients (25%) and could be ruled out in 78 patients (75%). Total agreement between MR and endoscopy could be reached in 74 patients (71%). Histology indicated absence of inflammation in 50 patients (48%). MR and endoscopic findings were concordant in 38 patients (76%) and 37 patients (74%), respectively. Corresponding results by ileocolonoscopy were 37 true negative, 29 true positive, 4 false positive, and 12 false negative (sensitivity, 70.7%; specificity, 74%). MR enterography with a 3.0-T scanner is a powerful tool in the evaluation of ileal diseases, and has therefore made MR enterography the first-line modality at our institution in patients with suspected inflammatory bowel disease.

Computed tomography angiography evaluation of internal carotid artery free-floating thrombus—single-center diagnosis, false-positives, and follow-up

The incidence and management of free-floating thrombus (FFT), also known as intraluminal carotid thrombus, within the internal carotid artery (ICA) are currently unknown. The first case series documenting FFT was published in 1966 [1]. There have been numerous case series publications describing FFT using various modalities mostly including angiography, duplex ultrasound (DU), and more recently computed tomography (CT). Based on retrospective studies, its incidence is estimated to be between 0.4–0.7 % and 0.05 % at cerebral angiography and DU, respectively [2–4]. A more recent single-center retrospective analysis using CT angiography (CTA) quoted the incidence at 3.1 % [5]. With current guidelines for imaging of acute stroke and transient ischemic attack, CTA and magnetic resonance imaging angiography are more frequently being performed in the urgent setting [6]. More than 90 % of patients with FFT develop neurologic sequelae [7]. The “donut sign” has been used to describe the appearance of FFT in the axial plane on CTA [5]. Further characterization of FFT is possible with multiplanar reformatted images and may help distinguish FFT from other mimickers. We present the CTA findings of FFT and describe its potentially unstable clinical course and its resolution on imaging after treatment. Potential false-positives, including complex ulcerated plaque, will be discussed.

Percutaneous MR-guided cryoablation of prostate cancer: initial experience

We report our initial experience and the technical feasibility of transperineal prostate cryoablation under MR guidance. Percutaneous MR-guided cryoablation was performed in 11 patients with prostatic adenocarcinoma contraindicated for surgery (mean age: 72 years, mean Gleason score: 6.45, mean prostate-specific antigen (PSA): 6.21 ng/ml, T1-2c/N0/M0, mean: prostate volume 36.44 ml). Free-hand probe positioning was performed under real-time MR imaging. Four to seven cryoprobes were inserted into the prostate, depending on gland volume. The ice ball was monitored using real-time and high-resolution BLADE multi-planar imaging. Patients were followed at 1, 3, 6, 9 and 12 months after the procedure with serum PSA level and post-ablation MRI. Prostate cryoablation was technically feasible in 10/11 patients. The ice ball was clearly and sharply visualised in all cases as a signal-void area. Mean ice-ball volume was 53.3 ml. Mean follow-up was 15 months (range: 1-25). Mean PSA nadir was 0.33 ng/ml (range: 0.02-0.94 ng/ml). Mean hospitalisation was 5 days (range: 3-13). Complications included a urethro-rectal fistula, urinary infection, transient dysuria and scrotal pain. MR-guided prostate cryoablation is feasible and promising, with excellent monitoring of the ice ball. Future perspectives could include the use of MR guidance for focal prostate cancer cryotherapy. • Magnetic resonance allows precise positioning of cryoprobes with real-time imaging. • High-resolution MRI allows excellent monitoring of the developing ice ball. • Cryoablation of prostate cancer under MR guidance is technically feasible. • Further work will refine the procedure and make it even safer.

Anatomical surgical planning for oral and oropharyngeal primary carcinoma combined with adjuvant treatment where indicated is associated with improved local control

We aimed to find out whether surgical tactics that lead to a reduction in tumour-involved surgical margins also improve local control. We retrospectively reviewed a consecutive case series (n=162) of previously untreated patients who had operations for squamous cell carcinoma (SCC) of the oral cavity or oropharynx. Extensive use was made of computed tomographic multiplanar imaging to plan primary resections. Nine patients (6%) had tumour at the resection margin. Local control at 36 months was 96%, disease-specific survival (DSS) was 86%, and overall survival (OS) was 77%. Carefully planned primary operation for SCC of the oral cavity and oropharynx to minimise tumour-involved margins combined with conventional adjuvant treatment where indicated, is associated with a high probability of local control and disease-specific survival.

Comparison of multi-detector row computed tomography with echocardiography for assessment of left ventricular function in healthy dogs

To evaluate the use of retrospectively ECG-gated, contrast-enhanced, multi-detector row computed tomography (MDCT) for assessment of left ventricular function in dogs and to compare the results with those obtained by use of 2-D and M-mode echocardiographc techniques. 10 healthy Beagles. Dogs underwent MDCT (performed by use of a 64-detector row CT system) and echocardiography under general anesthesia. Left ventricular end-systolic volume (ESV), end-diastolic volume (EDV), and ejection fraction (EF) were determined in MDCT-generated multiplanar reformatted images by use of Simpson and biplane area-length calculation methods. Results were compared with left ventricular ESV, EDV, and EF determined in echocardiographc images by use of Teichholz and bullet method calculations. Results were evaluated via Deming regression analysis and Pearson correlation tests. Bland-Altman analysis was used to assess limits of agreement and systematic errors between the 2 methods. Mean values for EDV and ESV determined by use of MDCT were highly correlated with those determined by use of echocardiography, regardless of the calculation methods compared (r = 0.91 to 0.96); volumes determined by use of MDCT appeared to be higher than those determined by use of echocardiography, although most differences were nonsignificant. Mean EF determined by use of MDCT with the Simpson calculation method was highly correlated with that determined by use of echocardiography with bullet method calculations (r = 0.90). Results suggested that assessment of left ventricular volume and function in dogs is feasible with MDCT. To estimate left ventricular EF with MDCT. use of the Simpson calculation method is advised.

Multiplanar CT for Suspected Pediatric Pulmonary Emboli

Research Article| March 01 2012 Multiplanar CT for Suspected Pediatric Pulmonary Emboli AAP Grand Rounds (2012) 27 (3): 31. https://doi.org/10.1542/gr.27-3-31 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Multiplanar CT for Suspected Pediatric Pulmonary Emboli. AAP Grand Rounds March 2012; 27 (3): 31. https://doi.org/10.1542/gr.27-3-31 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search nav search search input Search input auto suggest search filter All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: pulmonary embolism Source: Lee EY, Zucker E, Tsai J, et al. Pulmonary MDCT angiography: value of multiplanar reformatted images in detecting pulmonary embolism in children. AJR. 2011; 197(6): 1460– 1465; doi: https://doi.org/10.2214/AJR.11.6886Google Scholar Investigators from several Boston medical centers sought to determine whether the addition of two-dimensional reconstructed images (especially in sagittal and coronal planes) to routine axial views aided radiologists in assessing computed tomography (CT) scans performed in children/adolescents for possible pulmonary emboli (PE). For the study, CT angiography (CTA) scans with nonionic contrast were performed in consecutive patients under the age of 18 years with clinically suspected PE at Children’s Hospital Boston. Each patient underwent multiplanar reformatted (MPR) multidetector (MD) CTA. Except for two children (both younger than 5 years), patients were not sedated, kept supine, and imaged in one breathhold at end inspiration. Studies limited by... You do not currently have access to this content.

Application of cone beam computed tomography for assessment of the temporomandibular joints

Radiographic examination is essential for the diagnosis and management of temporomandibular joint (TMJ) disorders. The goals of TMJ radiography are to evaluate cortical and trabecular architecture of the bony structures and confirm their integrity, to assess the extent and monitor progression of osseous changes, and to evaluate the response to treatment. Accurate evaluation of the TMJ by conventional radiography is limited by structure superimposition. Cone beam computed tomography (CBCT) provides high-resolution multiplanar images and delivers substantially lower radiation dose, compared with multislice CT. CBCT allows examination of TMJ anatomy without superimposition and distortion to facilitate analysis of bone morphology, joint space and dynamic function in all three dimensions. This article will describe the role of CBCT imaging for the assessment of the TMJ osseous structures and present typical appearances of common pathological conditions of the TMJ.

Evaluation of the vestibular aqueduct in Ménière's disease using multiplanar reconstruction images of CT

Previous studies, in which the vestibular aqueduct (VA) was determined using axial CT, have indicated that the VA sizes in patients with Ménière's disease were smaller than those in the subjects of the control group and that 25-35% of ears with Ménière's disease were "non-visible type." In this study, in addition to obtaining the axial size, we measured the VA size along the vertical plane by using vertical multiplanar reconstruction (MPR) images. The VA size of both ears of patients with unilateral Ménière's disease (n=34) and of subjects of the control group (n=30) was measured by using the vertical MPR and the axial CT images. The VA size was measured along the axial and vertical planes in all subjects. The parameters measured on the axial image of the VA correlated with each other; however, the parameters on the vertical MPR image did not correlate with those on the axial image. Values of parameters in the affected and nonaffected ears with Ménière's disease tended to be smaller than those in the control ear. The external aperture areas of the VA fenestra of the affected and nonaffected ears of patients with Ménière's disease were significantly smaller than that for the control ears. Our findings suggest that the vertical parameters of the VA yield information that is independent of that provided by the axial parameters. In both ears of patients with unilateral Ménière's disease, the VA tended to be thinner than those in the control ear.