Value of digital volume tomography in patients with conductive hearing loss

Evaluation of the Morphometry of the Stylomastoid Foramen in the Turkish Population: A Retrospective Study Using Cone-Beam Computed Tomography (CBCT)

Objectives  This study aimed to investigate the morphometric features of the stylomastoid foramen (SMF) and the facial canal in the Turkish population using cone-beam computed tomography (CBCT) retrospectively. Methods  The randomly selected 479 patients aged from 8 to 87 years were examined, and a total of 958 CBCT images of the SMF and facial canal (FC) were analyzed. The diameter of the SMF and FC at the mastoid segment and their relation to age, gender, and side were evaluated. Statistical analyses were performed using Kolmogorov-Smirnov, one-way analysis of variance, Student's t -test, chi-squared test, Tukey's honestly significant difference, and Fisher-Freeman-Halton exact test. p -Values < 0.05 were accepted as statistically significant at the 95% confidence interval. Results  The mean age of the patients was 40.49 ± 19.73 years. The mean diameter of the right SMF was 2.24 ± 0.58 and 2.50 ± 0.63 mm in females and males. The mean diameter of the left SMF was 2.25 ± 0.56 and 2.44 ± 0.62 mm in females and males. The mean diameter of the right FC was 1.60 ± 0.35 and 1.70 ± 0.34 mm in females and males. The mean diameter of left FC was 1.55 ± 0.35 and 1.66 ± 0.33 mm in females and males. A statistically significant difference was found between the age groups in terms of the mean SMF and FC diameter on both sides ( p  < 0.05). Conclusion  Information obtained from this study regarding the morphometric features of the SMF and thereby FC may assist surgeons in treatment plans and reduce the risk of neurosurgical complications.

The morphometric analysis of mastoid foramen and mastoid emissary canal on cone-beam computed tomography (CBCT)

PURPOSE

The purpose of this retrospective study was to assess the prevalence and morphometric features of the mastoid foramen (MF) and mastoid emissary canal (MEC) using cone-beam computed tomography (CBCT), as well as their relationship with age, sex, and side.

METHODS

CBCT scans of 500 patients aged 8-87 years were examined retrospectively. The presence and number of MF, mean diameter of the MEC and MF, MF location, and the distance between MF and asterion were all examined. The collected data were subjected to appropriate statistical analysis. P values < 0.05 were accepted as statistically significant at a 95% confidence interval.

RESULTS

The study included 472 patients. MF was present in 82% and absent bilaterally in 18% of the 472 patients. The prevalence of MF was 67.8% on the right side and 65.7% on the left. The mean diameter of the MF was 3.39 ± 1.48 mm and the number of the MF ranged from zero to four. The mean diameter of the MEC was 2.05 ± 1.06 mm and the distance between MF and asterion was 22,46 ± 5,18 mm. 52.4% of the MF was observed on the occipito-mastoid suture.

CONCLUSION

To prevent surgical complications, particularly those that concern the temporal and mastoid areas, radiologists should report the results of the preoperative examination of the morphometry of the MF and MEC. CBCT imaging is a reliable diagnostic method that can be used to evaluate the MEC and MF before surgical procedures.

Insight in to the Awareness of CBCT as an Imaging Modality in the Diagnosis and Management of ENT Disorders: A Cross Sectional Study

The advent of Cone-beam computed tomography (CBCT), has revolutionized 3D imaging in dentistry. CBCT has enormous potential to be used as an alternative imaging modality by Otolaryngologists. But their knowledge regarding CBCT is limited. The study aims to evaluate the awareness of CBCT as an imaging modality among Ear, nose and Throat (ENT) practitioners. The validated questionnaire was sent by email and the participants were asked to fill the google form through the link provided to record the responses. The participants were asked to answer 25 multiple choice questions regarding the general information and practice related to CBCT imaging. Data was evaluated according to the descriptive statistics and the Chi-square test was used to determine the test of significance. The response rate for this study was 84.4%. The mean age of the participants was 44.9 ± 11.3. 69% of the respondents were academicians,14.2% had exclusive clinical practice, and 16.8% had both clinical and academic exposure. Among the study population, 76.8% had never advised CBCT in their practice. Only 10.3% of the study participants were aware of the potential of CBCT in ENT disorders. The mean knowledge, attitude and practice scores were very low regarding the applications of CBCT. Most of the study participants advised CBCT for maxillofacial fractures (78.1%) and was statistically significant p < 0.05. The knowledge about various advantages and clinical applications of CBCT among Otolaryngologists is limited. However, continuing medical education and inclusion in the medical curriculum will increase the scope and awareness about CBCT among ENT fraternity.

Morphometric Analysis of Cleft Lip Palate and Prognathic Mandibles in Relation to Mandibular Canal Course

INTRODUCTION

This study aimed to evaluate the mandibular canal course in individuals with cleft lip palate (CLP) and mandibular prognathism in terms of the sagittal split-ramus osteotomy using cone-beam computed tomography.

MATERIALS AND METHODS

Individuals with CLP older than 16 years of age and planned to undergo Le fort I + SSR osteotomies and those with class III occlusion planned to undergo Le fort I + SSR osteotomies were included. The measurements on the cleft side of CLP patients were compared with both their noncleft sides and those with class III occlusion. The course of the inferior alveolar nerve and its position in the mandible were evaluated starting from the mandibular foramen, the first entrance to the mandible, to the mental foramen, the exit from the mandible.

RESULTS

The distance between the mandibular canal and the buccal surface of the mandible (B3) on the plane tangent to the distal of the mandibular first molar and perpendicular to the occlusal plane was found to be greater in individuals with CLP (P = 0.011). Buccal cortex thickness (C4) at the level of the mandibular canal on the plane tangent to the distal of the mandibular second molar and perpendicular to the occlusal plane was found to be lower in individuals with CLP (P = 0.021).

CONCLUSIONS

The buccal cortex thickness of the mandible corpus and the distance of the mandibular canal to the buccal surface is different in patients with CLP compared to class III individuals' posterior to the mandible. Surgeons should take these differences into consideration during mandibular osteotomy.

Image quality of flat-panel computed tomography using 2 different acquisition times versus multidetector computed tomography in whole-head temporal bone specimen

PURPOSE

Imaging of temporal bone and skull base acquire high resolution due to the small anatomic structures with high clinical relevance. The purpose of this study was to compare image quality of the temporal bone in standard 20 s protocol flat-panel computed tomography (FPCT) with the new time- and dose improved 10 s protocol as well as with 128 slice multidetector computed tomography (MDCT). The aim was to evaluate the new time- and dose improved 10 s protocol.

METHODS

10 whole-skull preparations-20 temporal bones-were scanned with either 128 slice MDCT CT (SOMATOM Definition AS + , Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10 s or 20 s protocol.

RESULTS

We show here that overall FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the temporal bone compared to 128 slice MDCT. Especially the shorter, dose saving 10 s protocol of the FPCT is still superior to 128 slice MDCT. The 20 s FPCT protocol was only significantly superior in identification of the cochlear apical turn and can thereby be used specifically in clinical cases with pathologies in this area.

CONCLUSIONS

The 10 s FPCT protocol yields a significantly better image quality than MDCT in imaging finer structures of the temporal bone.

"Is Cone Beam Computed Tomography (CBCT) a Potential Imaging Tool in ENT Practice?: A Cross-Sectional Survey Among ENT Surgeons in the State of Odisha, India

This questioner survey aimed about awareness of the Cone Beam Computed Tomography (CBCT) machine and its various clinical applications in ENT, among the ENT surgeons in the state of Odisha. 150 questioner forms on CBCT were distributed to the all the participating ENT surgeons at a state level ENT conference, out of which the response rate was 110. The participants were asked to answer 30 multiple choice questions, which were divided into 3 parts; general information on CBCT, general approach to CBCT and practice related to CBCT. The statistical analysis of the data collected was carried out by a Chi square test to compare the means at a significance level of P < 0.05. The response rate for this study was 73%. The mean age of the participant ENT surgeons was 47.9 (±19.2). Of the study population, 71.2% (89) did not ever advice CBCT in their practice. Only 33.9% (38) of the population believed that CBCT is more beneficial in the field of ENT. Only 25% (28) knew that CBCT requires lower radiation dose than conventional CT. 28.1% (31) of population believed that the spatial orientation is better in CBCT than CT. 62.5% (69) of the population did not knew that CBCT can be used in imaging sinusitis of dental origins. 75% (83) of the population did not knew that CBCT can be used in diagnosis of obstructive sleep apnoea and visualizing airway space. Only 18.8% (21) of the study population agreed that the CBCT has the potential to replace conventional CT in ENT imaging in future. In the conclusion, this study clearly showed that the number of ENT surgeons advising CBCT imaging in their practice is very less. The knowledge about various advantages and clinical applications of CBCT had been very limited. However, through continuing medical education and conducting various seminars and workshops on CBCT, imparting chapters on CBCT, in the undergraduate and post graduate curriculum will definitely help increase the awareness on CBCT among ENT fraternity.

Flat Panel Angiography in the Cross-Sectional Imaging of the Temporal Bone: Assessment of Image Quality and Radiation Dose Compared with a 64-Section Multisection CT Scanner

BACKGROUND AND PURPOSE

Cross-sectional imaging of the temporal bone is challenging because of the complexity and small dimensions of the anatomic structures. We evaluated the role of flat panel angiography in the cross-sectional imaging of the temporal bone by comparing its image quality and radiation dose with a 64-section multisection CT scanner.

MATERIALS AND METHODS

We retrospectively collected 29 multisection CT and 29 flat panel angiography images of normal whole-head temporal bones. Image quality was assessed by 2 neuroradiologists, who rated the visualization of 30 anatomic structures with a 3-point ordinal scale. The radiation dose was assessed with an anthropomorphic phantom.

RESULTS

Flat panel angiography showed better image quality than multisection CT in depicting the anterior and posterior crura of the stapes, the footplate of the stapes, the stapedius muscle, and the anterior ligament of the malleus (P < .05). In contrast, multisection CT showed better image quality than flat panel angiography in assessing the tympanic membrane, the bone marrow of the malleus and incus, the tendon of the tensor tympani, the interscalar septum, and the modiolus of the cochlea (P < .05). Flat panel angiography had a significantly higher overall image quality rating than multisection CT (P = .035). A reduction of the effective dose of approximately 40% was demonstrated for flat panel angiography compared with multisection CT.

CONCLUSIONS

Flat panel angiography shows strengths and weaknesses compared with multisection CT. It is more susceptible to artifacts, but due to the higher spatial resolution, it shows equal or higher image quality in assessing some bony structures of diagnostic interest. The lower radiation dose is an additional advantage of flat panel angiography.

Direct comparison of conventional radiography and cone-beam CT in small bone and joint trauma

OBJECTIVE

To compare the diagnostic value of cone-beam computed tomography (CBCT) and conventional radiography (CR) after acute small bone or joint trauma.

MATERIALS AND METHODS

Between March 2013 and January 2014, 231 patients with recent small bone or joint trauma underwent CR and subsequent CBCT. CR and CBCT examinations were independently assessed by two readers, blinded to the result of the other modality. The total number of fractures as well as the number of complex fractures were compared, and inter- and intraobserver agreement for CBCT was calculated. In addition, radiation doses and evaluation times for both modalities were noted and statistically compared.

RESULTS

Fracture detection on CBCT increased by 35% and 37% for reader 1 and reader 2, respectively, and identification of complex fractures increased by 236% and 185%. Interobserver agreement for CBCT was almost perfect, as was intraobserver agreement for reader 1. The intraobserver agreement for reader 2 was substantial. Radiation doses and evaluation time were significantly higher for CBCT.

CONCLUSION

CBCT detects significantly more small bone and joint fractures, in particular complex fractures, than CR. In the majority of cases, the clinical implication of the additionally detected fractures is limited, but in some patients (e.g., fracture-dislocations), the management is significantly influenced by these findings. As the radiation dose for CBCT substantially exceeds that of CR, we suggest adhering to CR as the first-line examination after small bone and joint trauma and keeping CBCT for patients with clinical-radiographic discordance or suspected complex fractures in need of further (preoperative) assessment.

Differences of radiological artefacts in cochlear implantation in temporal bone and complete head

OBJECTIVES

Accurate radiological evaluation of cochlear implants is essential for improvement of devices and techniques and also for assessing the position of the electrodes within the cochlea. Radiological study of implants has focused on isolated temporal bones. Previous studies showed relevant sizes of artefacts (dimensions of the radiological image compared with the actual dimensions of the electrode) in visualization of cochlear implants in computed tomography and cone beam computed tomography (CBCT). In this study, we aimed to obtain CBCT images of cochlear electrodes in isolated temporal bones and in whole heads and to assess the differences in image quality between the two.

METHODS

Cochlear electrodes were implanted in three complete human heads. Radiological examinations were performed using a single CBCT scanner with varying x-ray tube currents, voltages, and rotation angles. The temporal bones were then removed and the same radiological examinations were repeated, with and without the receiver coils. Artefacts from a basal electrode (electrode 9) and an apical electrode (electrode 2) were calculated. These were compared with each other by measuring the diameter of the image of the electrode (electrode inclusive of imaging artefacts) and with the real electrode diameters from the manufacturer's data. Additionally, the radiological diameters (inclusive of artefact) of the electrodes were compared to the cross-sectional diameters of the basal and apical coils of the cochlea at the locations of these two electrodes.

RESULTS

In comparison to the real electrode diameters, radiological artefact proportions of 51-58% for electrode 9 and 56-61% for electrode 2 were calculated. The differences between whole head images (group 1) and temporal bone images with and without the receiver coil (groups 2 and 3) were highly significant for each protocol (P < 0.001).

DISCUSSION AND CONCLUSION

These results indicate that it is not possible reliably to determine the exact intracochlear positions of electrodes using CBCT. Imaging of isolated temporal bones produced significantly greater artefacts than imaging of the whole head. Evaluations of image quality based only on results for isolated temporal bones are not transferable to clinical situations, and should be assessed critically.

Visualisation of the Bonebridge by means of CT and CBCT

Background

With the Bonebridge, a new bone-anchored hearing aid has been available since March 2012. The objective of the study was to analyse the visualisation of the implant itself as well as its impact on the representation of the bony structures of the petrosal bone in CT, MRI and cone beam CT (CBCT).

Methods

The Bonebridge was implanted unilaterally in two completely prepared human heads. The radiological imaging by means of CBCT, 64-slice CT, 1.5-T and 3.0-T MRI was conducted both preoperatively and postoperatively. The images were subsequently evaluated from both the ENT medical and nd radiological perspectives.

Results

As anticipated, no visualisation of the implant or of the petrosal bones could be realised on MRI because of the interactive technology and the magnet artefact. In contrast, an excellent evaluability of the implant itself as well as of the surrounding neurovascular structures (sinus sigmoideus, skull base, middle ear, inner ear, inner auditory canal) was exhibited in both the CT and in the CBCT.

Conclusion

The Bonebridge can be excellently imaged with the radiological imaging technologies of CT and CBCT. In the process, CBCT shows discrete advantages in comparison with CT. No relevant restrictions in image quality in the evaluation of the bony structures of the petrosal bones could be seen.

Measurement and comparison of labyrinthine structures with the digital volume tomography: ancient Egyptian mummies' versus today's temporal bones

The objective of this study was to investigate whether the labyrinthine structures of ancient Egyptian mummies differ significantly from modern labyrinths. The new technique of digital volume tomography (DVT) was used to visualize the temporal bones. To obtain standardized images and measurements, precise instructions regarding volume rotation, slicing and measurements' positioning were determined. Twenty-five dimensions were obtained. The groups were compared statistically. No significant differences could be found except one cochlear diameter which proved to be significantly larger in the control group. DVT is applicable for imaging of temporal bones. Measurements might help to increase understanding of the temporal bone's structure, to aid the diagnostics of pathologies as well as to supplement the planning of surgical procedures.

Imaging of ancient Egyptian mummies' temporal bones with digital volume tomography

The radiographic imaging of ancient Egyptian mummies has always been of great interest. Computed tomography is the method of choice to demonstrate bony pathologies with high quality. As digital volume tomography (DVT) is an extension of panoramic tomography with a very high resolution, its qualities were evaluated by examination of temporal bones of Egyptian mummy skulls. Ten Egyptian mummy skulls from the Zoological Collection Marburg, estimated 1,700-5,000 years of age, from Abydos, Philae, Theben-West and Sakkarah, were examined by DVT (3D Accuitomo, Morita, Japan). Through a rotation 360° of the X-ray source around the region of interest, a cylinder of 3 × 4 cm was captured as a three-dimensional volume. The gained data were analyzed with the help of special software on a PC. The angles of the axial, coronal and sagittal sections were arbitrarily changed to represent single structures with high resolution of 0.125 mm to analyze specific anatomical structures. In all skulls, conditions of the temporal bone and its anatomical structures were evaluated and normal as well as pathological findings evaluated in detail. The analysis of special landmarks such as the ossicular chain, cochlea, external, and internal auditory canal, facial nerve canal, and semicircular canals showed an intact ossicular chain in six temporal bones, while only isolated and dislocated ossicles were found in eight temporal bones. Besides one dehiscence of the superior semicircular canal in one temporal bone which might have led to vertigo and deafness at lifetime, all other findings were normal. Fragments of foreign bodies additionally found in the labyrinth, external ear canal and intracranially were attributed to postmortem damage. Digital volume tomography extends the imaging possibilities of CT for paleoradiological evaluation of temporal bones. With its high resolution, geometric accuracy, reconstruction capabilities, rapidness, and comparably low costs, even small bony pathologies are precisely demonstrated in a limited area. Investigations of larger numbers of specimen might reveal further details of ancient history for further interdisciplinary investigation of anthropologists, Egyptiologists, otolaryngologists, and radiologists.

Analysis of pneumatization and neurovascular structures of the sphenoid sinus using cone-beam tomography (CBT)

BACKGROUND

The sphenoid sinus is a frequent target of paranasal sinus surgery. Because of the high risk of injuring the surrounding structures (e.g. internal carotid artery, optical nerve) a preoperative imaging is absolutely necessary.

PURPOSE

To analyze the possibilities of cone-beam computed tomography (CBCT), which is especially quite a new technique in ENT, in the evaluation of the sphenoid sinus, its surrounding structures, and the corresponding anatomical variations.

MATERIAL AND METHODS

This was a retrospective, single-centre study of 580 patients (1160 sides = cases). The Accu-I-Tomo-F17 was used. Pneumatization of sphenoid sinus, course of internal artery, course of optical nerve, and dehiscence of the bony canals were evaluated.

RESULTS

In the case of pneumatization a type I (completely missing or minimal sphenoid sinus) was found in two patients (0.3%), type II (posterior wall of sphenoid sinus is in front of the anterior wall of the sella) in 38 patients (6.6%), type III (posterior wall is between anterior and posterior wall of sella) in 332 patients (57,2%), type IVa (posterior wall is behind the posterior wall of sella without air dorsal the sella) in 104 patients (17.9%), and type IVb (similar to type IVa but with air dorsal the sella) in 104 patients (17.9%). In 1025 cases (89.5%) a smooth course of the internal carotid artery was found whereas a free course could be detected in 120 cases (10.5%). Defects of the bony canal of the optical nerve were found in 16.7% and of the internal carotid artery in 2.7% of the cases. The optical nerve showed a free course through the sphenoid in 151 cases (13.7%) and a smooth course in 1007 cases (87.0%).

CONCLUSION

CBCT could evaluate all relevant anatomic structures and answer the questions of different anatomical variants. A modified classification of the pneumatization of the sphenoid sinus could be described. Frequencies of anatomical variations are in accordance with the current literature of CT research.

Use of cone beam computed tomography in otolaryngologic treatments

Cone beam computed tomography (CBCT) allows us to evaluate 3-dimensional (3D) morphology of the maxillofacial skeleton and also used in dentomaxillofacial imaging to solve complex diagnostic and treatment planning problems such as craniofacial fractures, temporamandibular dysfunctions or sinus imaging. CBCT uses a rectangular or round 2D detector, which allows a single rotation of the gantry to generate a scan of the entire region of interest. Technological and application-specific factors such as development of compact, relatively low-cost, high-quality, large, flat-panel detector arrays; the availability of low-cost computers with processing power sufficient for cone beam image reconstruction; the fabrication of highly efficient radiograph tubes capable of multiple exposures necessary for cone beam scanning at prices lower than those currently used for fan beam CT; and limited volume scanning (e.g., head and neck) eliminating the need for subsecond gantry rotation speeds make this possible. The objective of this study is to review published evidence for CBCT having an important role in ORL treatments. We aimed to review all the available literature about the CBCT imagination in ORL treatments. Systematic literature search was performed using PubMed and Ovid. Additional literature was retrieved from reference lists in the articles. Systematic analysis of the literature from 1998 to 2010 was performed. A total of 40 abstracts were evaluated independently by two members of the project group, and 38 articles were included in the review.

Controlling the position and the dislocation of the middle ear transducer with high-resolution computed tomography and digital volume tomography: implications for the transducers' design

A minimal tip dislocation of the middle ear transducer (MET(®), Otologics Ltd) may result in poor hearing performance. Our objective was to examine if a defined MET dislocation can be diagnosed by high-resolution computed tomography (HRCT) or digital volume tomography (DVT). A human cadaver head was sequentially implanted with different MET tips (incus application) including a ceramic tip (T 1c), a titanium tip (T 1t), a new, thinner titanium tip (T 2), and a spherical titanium tip (Ts). HRCT and DVT studies were performed. Afterward, the tips were pulled back 0.5 mm, so that they were not attached to the incus. HRCT and DVT scans were repeated to identify the dislocation. Using the best plain in HRCT images, the dislocation of the transducer could be measured reliably and reproducibly in half of the cases. In particular, the precise positioning and the dislocation could be identified when T 1t and Ts were implanted, with the Ts showing the best visibility. DVT failed in recognizing the dislocation in all cases. The identification of MET tip's dislocation with HRCT depends on the shape, size, and material of the tip. This knowledge is useful for the design of the implants, as determination of the right position of the middle ear transducer may be proven important for the hearing outcome. In some cases, however, surgical exploration may still be required. Although DVT represents a promising imaging method for the otologists, it can barely help when MET dislocation is suspected.

Artifacts of the electrode in cochlea implantation and limits in analysis of deep insertion in cone beam tomography (CBT)

Until now more than 250,000 cochlea implantations have been performed worldwide. The surgical procedure is well standardized. A discussion about the kind of postoperative radiological control has started since cone beam tomography (CBT) has been established in ENT and hearing preservation operations have come more into the focus. Further research has been concentrated on the role of CBT and the insertion of the basal turn. The aim of this study was to look for the possibilities of CBT and deep insertion. The second aim was to analyze the artifacts of cochlea implants in CBT. Three human cadaver ears were implanted with a flex soft electrode of MedEl© in a standard operation procedure with round window insertion and a full insertion. Afterwards 72 CBT sets per ear were performed with different X-ray-tube currents (2-10 mA), voltages (72-90 kV), and exposure times (9 and 17 s). On each data set, the radiological diameter of the electrode 9 (basal), electrode 2 (apical), the diameter of the cable next to the electrodes 9 and 2, and the associated diameter of the cochlea next to the electrodes 9 and 2 were evaluated. Additionally, a comparison to the real diameter was done. The mean radiological diameters of the measure point at electrode 9 were: electrode = 1.19 mm; cable = 0.65 mm; cochlea = 1.77 mm. Results for measure point at electrode 2 were: electrode = 0.98 mm; cable = 0.48 mm; cochlea = 1.21 mm. The real diameters were at electrode 9 in lateral view 0.58 mm and in top view 0.63 mm and at electrode 2 in lateral view 0.36 mm and in top view 0.50 mm. Differences between the diameters of the electrode 9 and 2 were highly significant. Interestingly, the real diameter of the electrode is half in comparison to the radiological one. Also in comparison to the diameter of the cable and the associated electrode is nearly half. Nearly 50% artifact exists on radiologic evaluation of the diameter of the electrode. Varying the X-ray adjustments did not lead to optimized results. The difficulties in evaluating a cochlea electrode with CBT could be shown. The high rate of artifacts (50%) makes it extremely difficult to predict the inserted scale, especially when evaluating the intracochlear position in the medial and apical turn of the cochlea. In conclusion, until now CBT allows a relatively safe evaluation of the electrode in the basal turn, whereas in deep insertion it is not really a useful tool to answer the question of insertion trauma, implanted scale, or scale displacements.

Analysis of the fossa olfactoria using cone beam tomography (CBT)

CONCLUSION

A cone beam tomography (CBT) examination of the olfactory area with its different variants allows development of an individual anatomical-radiological risk profile of the ethmoid and the identification of so-called 'dangerous ethmoids.'

OBJECTIVE

Preoperative imaging performed with high-resolution CBT is imperative for analysis of the risk of injuring the olfactory fossa during sinus surgery. This study aimed to analyze the relevant parameters.

METHODS

This was a retrospective, single-center study of 141 patients. The Accu-I-Tomo F17 was used. Keros type, the point of the anterior ethmoid artery, and the angle between the lateral lamella and the cribriform plate (α(lc)) were evaluated.

RESULTS

The Keros types were distributed as follows: type I, 13% (α(lc): 131°); type II, 64% (α(lc): 116°); type III, 23% (α(lc): 108°) (p < 0.001). The angle of the olfactory fossa and the position of the anterior ethmoid artery (free course: α(lc)=112° vs integrated into the skull base: α(lc)= 120°) was significantly different.

DISCUSSION

Surgical procedures in Keros type III where the height of the lateral lamella is much longer than in type II or type I, with an angle of nearly 107° between the lateral lamella and the cribriform plate, are expected to be safer in comparison with Keros type II with 116° and Keros type I with 131°.

Finger fractures imaging: accuracy of cone-beam computed tomography and multislice computed tomography

OBJECTIVE

To compare the diagnostic accuracy and radiation exposure of cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) in the evaluation of finger fractures.

MATERIALS AND METHODS

In a 3-year period, 57 consecutive patients with post-traumatic fractures of the metacarpal-phalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints with involvement of the articular surface were studied by means of CBCT and MSCT. Student's t test was used to compare CBCT and MSCT accuracy in evaluating the percentage of joint surface involvement and in detecting bone fragments. The average tissue-absorbed doses of CBCT and MSCT were also compared. A value of p < 0.05 was considered statistically significant. Inter-observer agreement was calculated.

RESULTS

In all cases, CBCT allowed the percentage of articular involvement to be correctly depicted compared with MSCT, showing 100% sensitivity and specificity (p < 0.001). A total of 103 bone fragments were depicted on MSCT (mean 3.8 per patient, range 1-23). CBCT indicated 92 out of 103 fragments (89.3%) compared with MSCT (mean diameter of missed fragments 0.9 mm, range 0.6-1.3 mm), with no statistically significant difference between CBCT and MSCT (p < 0.025). Multislice CT radiation exposure was significantly higher than that of CBCT (0.18 mSv vs 0.06 mSv, p < 0.0025). Inter-observer agreement was good (overall κ = 0.89-0.96).

CONCLUSIONS

Cone beam CT may be considered a valuable imaging tool in the preoperative assessment of finger fractures, when MSCT is not available.

Digital volume tomography (DVT) as a diagnostic modality of the anterior skull base

CONCLUSION

Because of high resolution and the relatively lower costs in comparison with modern helical CT scanners, digital volume tomography (DVT) can be recommended in the diagnosis of the nasal cavity and paranasal sinuses.

OBJECTIVES

DVT is an advancement of panoramic tomography and is based on the principles of rotational tomography. It enables high resolution visualization of osseous structures. The slices can be displayed in three orthogonal planes that can be changed in angle arbitrarily. Data volumes of up to 12×17 cm can be examined with a new generation of the DVT. The aim of this study was to point out the potential of DVT in the anterior skull base.

SUBJECTS AND METHODS

DVT scans with a cylindrical size of 10 cm in diameter and 10 cm in height were performed in 23 patients. The identification of surgical key landmarks (uncinate process, middle turbinate, ethmoidal bulla, agger nasi cells, Haller cells, frontal recess, anterior ethmoidal artery in its relationship to the skull base, the cribiform plate of the sphenoidal sinus in relation to the optic nerve, and the internal carotid artery) was evaluated.

RESULTS

Display of the essential surgical key landmarks was possible in all patients.

Conebeam CT of the head and neck, part 2: clinical applications

SUMMARY

Conebeam x-ray CT (CBCT) is being increasingly used for point-of-service head and neck and dentomaxillofacial imaging. This technique provides relatively high isotropic spatial resolution of osseous structures with a reduced radiation dose compared with conventional CT scans. In this second installment in a 2-part review, the clinical applications in the dentomaxillofacial and head and neck regions will be explored, with particular emphasis on diagnostic imaging of the sinuses, temporal bone, and craniofacial structures. Several controversies surrounding the emergence of CBCT technology will also be addressed.

Temporal bone imaging: comparison of flat panel volume CT and multisection CT

BACKGROUND AND PURPOSE

A recent development in radiology is the use of flat panel detectors in CT to obtain higher-resolution images. This technique is known as flat panel volume CT (fpVCT). We sought to compare the image quality and diagnostic value of 2 different flat panel detector-equipped scanners: one is a prototype fpVCT scanner, and the other is a so-called flat panel digital volume tomography (fpDVT) scanner, which is routinely used in clinical setup with current state-of-the-art multisection CT (MSCT) scanners.

MATERIALS AND METHODS

Five explanted temporal bones and 2 whole-head cadaveric specimens were scanned with fpVCT, fpDVT, and MSCT scanners. The image series were blindly evaluated by 3 trained observers who rated 38 anatomic structures with regard to their delineation/appearance.

RESULTS

Although the image quality obtained with fpVCT and fpDVT was rated significantly better compared with MSCT on isolated temporal bones, the differences were not significant when whole cadaveric heads were scanned.

CONCLUSIONS

Theoretic and practical advantages exist for flat panel detector-equipped scanners, including improved image quality. However, when imaging whole cadaveric heads, no significant difference could be demonstrated between them and standard-of-care MSCT.

Bionic ear imaging

PURPOSE

The aim of this study was to illustrate the different imaging features of middle and inner ear implants, brainstem implants and inferior colliculus implants.

MATERIALS AND METHODS

We retrospectively reviewed the computed tomography (CT) images of 468 patients with congenital or acquired transmissive or neurosensory hearing loss who underwent surgery. The implants examined were: 22 Vibrant Soundbridge implants, 5 at the long limb of the incus and 17 at the round window, 350 cochlear implants, 95 brainstem implants and 1 implant at the inferior colliculus. All patients underwent a postoperative CT scan (single or multislice scanner) and/or a Dentomaxillofacial cone-beam CT scan (CBCT) (axial and multiplanar reconstruction), and/or a plain-film radiography to visualise the correct position of the implant.

RESULTS

The CBCT scan depicts Vibrant site of implant better than plain-film radiography, with a lower radiation dose compared to CT. For cochlear implants, a single plain radiograph in the Stenvers projection can directly visualise the electrodes in the cochlea. All patients with brainstem or inferior colliculus implants underwent postoperative CT to exclude complications and the assess correct implantation, but the follow-up of these implants can be performed by plain radiography alone.

CONCLUSIONS

CT and CBCT scans are reliable and relatively fast methods for precisely determining the location of middle ear implants. CBCT is preferable to CT because of the lower radiation dose administered; a single plain-film radiograph is enough to visualise and follow-up cochlear, brainstem and inferior colliculus implants.