Temporal Scans Research Articles

CT Virtual Endoscopy in Assessing Ossicular Chain Disruption Csused by Temporal Bone Fracture and Ear Trauma

ObjectiveTo explore the value of computed tomography virtual endoscopy (VE) in assessing ossicular chain disruption in temporal bone fracture and ear trauma with intact tympanum. MethodsHigh resolution spiral computerized tomography (CT) was completed in 35 cases of temporal bone fracture and 5 cases of tympanum trauma, all with intact or healed tympanum. Three-dimensional reconstruction was completed using a virtual endoscopy software. Audiological tests were conducted in all patients and evaluation of facial nerve injury in patients with facial paralysis. Patients with mild conductive deafness, ossicular chain subluxation on VE, and no facial paralysis were treated conservatively for 4-12 weeks with repeated hearing evaluation; those with facial paralysis underwent surgery if no recovery after 4-8 weeks of conservative treatment. Patients with moderate to severe conductive hearing loss or mixed hearing loss, incus long process fracture or dislocation on VE and facial paralysis, underwent ossicular chain reconstruction and facial nerve decompression after conservative treatment for 4-8 weeks, or exploratory tympanotomy only if no facial paralysis. VE, audiological tests and facial nerve function tests were repeated in 3-6 months after surgery. ResultsOf the 6 cases with mild conductive hearing loss, ossicular chain subluxation and no facial paralysis, 3 recovered to normal hearing spontaneously and 3 showed no significant improvement, after 4-12 weeks of conservative treatment. After conservative treatment for 4-8 weeks, 3 of the 12 cases with mild conductive deafness, ossicular chain dislocation on VE and facial paralysis recovered to normal hearing and House-Brackmann (HB) grade I facial function from HB grade II, 4 showed facial function recovery to HB grade I (n=2) or II (n=2) from HB grade III but no hearing recovery, and 5 gained no recovery and went on to receive exploratory tympanotomy and facial nerve decompression. The 11 cases with moderate to severe conductive deafness, incus long process fracture or dislocation on VE and facial paralysis all received ossicular chain reconstruction and facial nerve decompression after 4-8 weeks of conservative treatment. The 7 cases with moderate to severe conductive deafness, dislocated or fallen incus on VE but no facial paralysis received ossicular chain reconstruction after conservative treatment. The 4 cases with mixed hearing loss, dislocated or fallen incus on VE and no facial paralysis received ossicular chain repair via the intact canal wall epitympanum approach after conservative treatment. Pharmacological therapies continued postoperatively in these patients to treat sensorineural deafness. Although temporal bone CT scans displayed the fracture line and malleus/incus abnormalities, VE provided additional detailed information on dislocation of incudomalleal and incudostapedial joints, incus dislocation or fracture, separation between crus longum incudis and stapes, and incus shifting. These were all confirmed during surgery. VE results and surgery findings were 100% consistent in patients with ossicular chain disruption. ConclusionVE can provide reliable visual evidence for accurate assessment of traumatic ossicular chain disruption, timing of surgery and individualizing surgical strategies and postoperative follow-up.

Multislice Computed Tomography Overestimates Superior Semicircular Canal Dehiscence Syndrome

We assessed the prevalence of superior semicircular canal dehiscence (SSCD) through examination of ultrahigh-resolution computed tomography (CT) scans of the temporal bone and attempted to verify the correspondence between a radiologic diagnosis of SSCD and clinical signs of SSCD syndrome. A prospective study was carried out on 191 consecutive patients who underwent temporal bone ultrahigh-resolution CT scans. Cases that matched the radiologic diagnosis of SSCD were subsequently referred for a comprehensive audiological evaluation that might enable a final diagnosis of SSCD syndrome. Among the 191 patients, 17 had a radiologic diagnosis of SSCD, which was bilateral in 5 cases, for a total of 22 SSCD cases, with a prevalence rate of 5.8%. In 2 of the 17 patients, the audiological examination revealed signs and symptoms indicative of SSCD syndrome, with a total prevalence rate of 0.5%. Our data confirm that the radiologic diagnosis of SSCD, performed by mean thin-section CT scans reformatted in the plane of the superior semicircular canal, is not necessarily related to the clinical presentation of SSCD syndrome. Our study also showed a prevalence rate of SSCD syndrome that was similar to the prevalence of SSCD reported from studies of histologic specimens.

Diagnostic value of cone-beam CT in histologically confirmed otosclerosis

This retrospective case review was performed with the aim to asses the value of cone-beam computed tomography (CBCT) in the preoperative diagnosis of otosclerosis. A total of 32 patients with histologically confirmed stapedial otosclerosis, who underwent unilateral stapedectomies were analyzed. Preoperative temporal bone CBCT scans were performed in all cases. CBCT imaging was characterized by a slice thickness of 0.3 mm and multiplanar image reconstruction. Histopathologic examination of the removed stapes footplates was performed in all cases. Findings of CBCT were categorized according to Marshall's grading system (from grade 0 to grade 3). Histopathologic results were correlated to multiplanar reconstructed CBCT scans, respectively. Histologically active foci of otosclerosis (n = 21) were identified by CBCT in all cases with a sensitivity of 100 %. However, CBCT was unable to detect histologically inactive otosclerosis (n = 11, sensitivity = 0 %). According to CBCT scans, no retrofenestral lesions were found and all positive cases were recruited into the grade 1 group indicating solely fenestral lesions at the anterior pole of stapes footplates. In conclusion, CBCT is a reliable imaging method with considerably lower radiation dose than high-resolution CT (HRCT) in the preoperative diagnosis of otosclerosis. These results indicate that CBCT has high sensitivity and specificity in the detection of hypodense lesions due to histologically active otosclerosis.

Temporal changes in magnetic resonance imaging in the mdx mouse

BackgroundDuchenne muscular dystrophy (DMD) is characterized clinically by severe, progressive loss of skeletal muscle. The phenotype is much less severe in the mdx mouse model of DMD than that seen in patients with DMD. However, a “critical period” has been described for the mdx mouse, during which there is a peak in muscle weakness and degeneration/regeneration between the 2nd and 5th weeks of life. A number of studies have employed small animal magnetic resonance imaging (MRI) to examine skeletal muscle in various dystrophic models, but such studies represent a snapshot in time rather than a longitudinal view.ResultsThe in vivo cross-sectional T2-weighted image of the healthy (wild type, WT) muscles is homogeneously dark and this homogeneity does not change with time, as there is no disease. We, and others, have shown marked changes in MRI in dystrophic muscle, with multiple, unevenly distributed focal hyperintensities throughout the bulk of the muscles. Here we monitored an mdx mouse using MRI from 5 to 80 weeks of age. Temporal MRI scans show an increase in heterogeneity shortly after the critical period, at 9 and 13 weeks of age, with a decrease in heterogeneity thereafter. The 4.3-fold increase in percent heterogeneity at week 9 and 13 is consistent with the notion of an early critical period described for mdx mice.ConclusionsAge is a significant variable in quantitative MR studies of the mdx mouse. The mdx mouse is typically studied during the critical period, at a time that most closely mimics the DMD pathology, but the preliminary findings here, albeit based on imaging only one mdx mouse over time, suggest that the changes in MRI can occur shortly after this period, when the muscles are still recovering.

영역 이진화 모델링과 지역적 변형 모델을 이용한 시간차 흉부 CT 영상의 폐 실질 비강체 정합 기법

본 논문에서는 시간차 흉부 CT 영상의 폐 실질 비강체 정합을 위하여 영역 이진화 모델링과 지역적 변형 모델을 이용한 정합 기법을 제안한다. 제안 기법은 먼저 폐 혈관과 실질을 분할하고, 영역 이진화 모델링을 수행하여 두 영상 사이의 밝기값의 차이에 따른 정합 오차를 최소화 한다. 다음으로 초기 정합 기법으로 두 폐 표면을 전역적으로 정렬하고, 지역적 변형 변환 모델을 제안하여 비강체 정합을 수행한다. 또한, 정합 후 감산된 시간에 따른 밝기값 차이가 미리 정의된 칼라 맵을 이용하여 가시화 된다. 실험 결과는 제안기법이 10명의 환자에 대하여 최대호흡과 최소호흡 CT 영상에서 폐 실질을 정확하게 정합하였음을 보여주었다. 제안된 비강체 정합 기법은 폐 실질에 대한 정량적 분석 결과의 직관적인 칼라 매핑을 통하여 다양한 폐 질환의 정량적 분석에 유용하게 사용될 수 있다. In this paper, we propose a non-rigid registration method of lung parenchyma in temporal chest CT scans using region binarization modeling and locally deformable model. To cope with intensity differences between CT scans, we segment the lung vessel and parenchyma in each scan and perform binarization modeling. Then, we match them without referring any intensity information. We globally align two lung surfaces. Then, locally deformable transformation model is developed for the subsequent non-rigid registration. Subtracted quantification results after non-rigid registration are visualized by pre-defined color map. Experimental results showed that proposed registration method correctly aligned lung parenchyma in the full inspiration and expiration CT images for ten patients. Our non-rigid lung registration method may be useful for the assessment of various lung diseases by providing intuitive color-coded information of quantification results about lung parenchyma.

Risk analysis of unilateral severe-to-profound sensorineural hearing loss in children

ObjectiveTo explore the etiology of pediatric unilateral severe-to-profound sensorineural hearing loss (USPSNHL) and the risk of hearing loss in the contralateral ear. MethodsPediatric patients with USPSNHL referred to a tertiary children's hospital for unilateral bone-anchored hearing aid implantation were identified for study. Clinical charts, audiograms, and radiographic imaging of the temporal bones were reviewed. ResultsEighty-four children with USPSNHL were reviewed (40 male, 44 female). The etiology of USPSNHL could be identified in 35 patients (41.7%), with perinatal events (16.2%) and family history of hearing loss (10.0%) being the most common identifiable risk factors. Forty percent of children with available newborn hearing screens passed in both ears but later developed USPSNHL. Progressive unilateral hearing loss leading to USPSNHL was found in 21% percent of patients. No patient experienced worsening hearing in the contralateral ear (mean follow-up=31.9 months). Of the 49 temporal bone scans available for review, 40.8% demonstrated aberrant inner ear anatomy, including semicircular canal dysplasia (10.2%), cochlear aperture stenosis (10.2%), hypoplastic cochlea (8.1%), enlarged vestibular aqueduct (14.3%), incomplete partition I/II (6.1%), and anomalous internal auditory canal (2.0%). ConclusionPediatric USPSNHL can be attributed to a variety of sources with a cause identifiable in approximately 40% of patients. Temporal bone CT scan acquisition appears to be relatively high yield in this patient population, but only rarely do results have clinical implications. Early follow-up suggests that this population of children with USPSNHL does not appear to have a significantly increased risk for hearing loss in the contralateral ear.

The petromastoid canal in the young child: Appearance on computed tomography

ObjectiveThe adult petromastoid canal (PMC) is a thin anatomical structure, but in young children, it can be wide on high resolution CT (HRCT) scans. We performed this study to evaluate the year-by-year change in width and shape of the PMC in the young child. Materials and methodsWe retrospectively reviewed temporal bone HRCT scans, performed between 2007 and 2012. Eighty children were included (age range: 0.3–6.9 years; median age: 3.1 years; 56% male). All scans had a slice thickness of ≤1mm. ResultsThe average width of the PMC was 1.95mm in children <2 years, compared to 0.83mm in children ≥2 (p<0.001). We categorized the PMC into 4 subtypes. A bulky (type III) PMC was predominant <2 years. A thin curvilinear (type I) PMC was more prevalent in the older children. Type II and IV PMC were found infrequently. The PMC width correlated inversely with the degree of pericapsular ossification (p<0.001), and mastoid pneumatisation (p<0.001). ConclusionA wide PMC (≥1mm) is a common finding in children <2 years. As children grow older, the PMC progressively narrows. This correlates to increased temporal bone pneumatisation and ossification of the otic capsule.

Investigation of temporal bone asymmetry in cases with unilateral tinnitus: morphometric and multicentric clinical study

The aim of this multicentric study was to compare the anatomical structures of temporal bone in patients with unilateral tinnitus with their healthy ears. We also aimed at evaluating whether age and gender-related asymmetrical changes occur in temporal bones or not. Fifty two ears of 26 patients who had unilateral tinnitus were included into the retrospective study. The patients who had subjective nonpulsatile tinnitus and who previously had temporal computed tomography according to their file records were accepted to study. Temporal CT scans and audiometric results of patients were examined retrospectively. Middle ear volume, diameter of internal acoustic meats and diameter of jugular bulb were evaluated by both anatomist and radiologist, interobserverly. Internal acoustic meats and jugular bulb were found larger in the ears that had tinnitus than healthy ears; however, there was no statistically significance. The stereological morphometrical study of temporal bone asymmetry in humans correlate with sex is of importance for both otolarygologs and anatomists. These results will contribute to data on middle ear volume, internal acustic meats and jugular bulb sizes.

Abstract P4-01-01: Integrating dynamic magnetic resonance imaging and gene expression profiling reveals novel therapeutic targets in locally advanced breast cancer.

Abstract Background: Despite advances in the treatment of breast cancer, there remains a significant clinical need for improved therapeutic strategies for patients with the most aggressive types of tumors. In particular, knowledge of the specific genes and pathways driving tumor growth in these patients would allow for treatment with therapeutics directed against these molecular targets. To this end, we reasoned that through the integrated analysis of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and gene expression profiling we could understand the molecular mechanisms associated with an aggressive imaging phenotype and thus gain insight into potential therapeutic targets for these patients. Materials and Methods: We studied 61 patients with locally advanced breast cancer, for whom DCE-MRI scans and core biopsies were available prior to the start of neoadjuvant chemotherapy. To analyse the DCE-MRI data, we used Tofts' pharmacokinetic (PK) model to quantify the rate constant kep that governs the washout of contrast agent from the tumor extravascular extracellular space. We chose to focus on the PK parameter kep since our analysis showed that it can be estimated reliably from the low temporal resolution diagnostic DCE-MRI scans that are routinely performed in the clinic. We extracted mRNA from formalin fixed paraffin embedded core biopsy samples and measured gene expression using Affymetrix U133 whole genome arrays. Following normalization and pre-processing, we used significance analysis of microarrays (SAM) to determine which genes were statistically significantly correlated with median kep. Results: Using a local false discovery rate of 5% resulted in a total of 328 genes that were significantly positively correlated with median kep. These included copper transporter like solute carrier family31member2 (SLC31A2), cancer stem cell (CSC) related genes such as CD44, aldehyde dehydrogenase family 1 member A3 (ALDH1A3), and integrin alpha-6 (ITGA6), hypoxia regulated genes such as hypoxia inducible factor 1a (HIF1a), kinases such as eukaryotic translation initiation factor2-alpha kinases (EIF2AK2, EIF2AK1), and pyruvate dehydrogenase kinases (PDK1, PDK3). Discussion: Our results illustrate how functional imaging modalities such as DCE-MRI can be combined with gene expression profiling to provide insight into molecular targets that may have important therapeutic implications in breast cancer. We found that locally advanced breast cancers with high vascular permeability and/or blood flow, as quantified by the washout parameter median kep, were associated with an up-regulation of genes related to CSCs and copper metabolism, the latter of which is known to play a role in angiogenesis. In addition, up-regulation of hypoxia related genes such as HIF1a, EIF2AK1&amp;2 and PDK1&amp;3 may promote tumor survival and spread under stress. Our results suggest that locally advanced breast cancers with high vascular permeability and/or blood flow may benefit from therapies directed at one or more of these molecular targets. Furthermore, functional imaging with DCE-MRI may be helpful as a noninvasive means of selecting and monitoring therapy against these targets. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-01-01.

Spectral domain optical coherence tomography imaging of the aqueous outflow structures in normal participants of the EPIC-Norfolk Eye Study

PurposeTo measure the dimensions of aqueous outflow structures and to investigate associations with intraocular pressure (IOP) and ocular biometry parameters in an older British population.MethodFifty-two participants from the European Prospective...

Aortic pulse wave velocity measurements with undersampled 4D flow‐sensitive MRI: comparison with 2D and algorithm determination

To compare pulse wave velocity (PWV) measurements obtained from radially undersampled 4D phase-contrast magnetic resonance imaging (PC-MRI) with 2D PC measurements and to evaluate four PWV algorithms. PWV was computed from radially undersampled 3D, 3-directionally velocity-encoded PC-MRI (4D) acquisitions performed on a 3T MR scanner in 18 volunteers. High temporal resolution 2D PC scans serving as a reference standard were available in 14 volunteers. Four PWV algorithms were tested: time-to-upstroke (TTU), time-to-peak (TTP), time-to-foot (TTF), and cross-correlation (XCorr). Bland-Altman analysis was used to determine inter- and intraobserver reproducibility and to compare differences between algorithms. Differences in age and PWV measurements were analyzed with Student's t-tests. The variability of age-corrected data was assessed with a Brown-Forsythe analysis of variance (ANOVA) test. 2D (4.6-5.3 m/s) and 4D (3.8-4.8 m/s) PWV results were in agreement with previously reported values in healthy subjects. Of the four PWV algorithms, the TTU, TTF, and XCorr algorithms gave similar and reliable results. Average biases of +0.30 m/s and -0.01 m/s were determined for intra- and interobserver variability, respectively. The Brown-Forsythe test revealed that no differences in variability could be found between 2D and 4D PWV measurements. 4D PC-MRI with radial undersampling provides reliable and reproducible measurements of PWV. TTU, TTF, and XCorr were the preferred PWV algorithms.

Terahertz detection using spectral domain interferometry

In this work, we present a novel method based on spectral domain interferometry for the electro-optic (EO) sampling of terahertz (THz) electric fields. This technique allows the use of thick crystals without the drawback of the over-rotation that may occur with intense THz sources, allowing longer temporal scans and thus, better spectral resolution. Using this technique, a phase difference of approximately 8898π can be measured, which is 18,000 times larger than the phase difference that could be measured using EO sampling.

Spatio‐Temporal Scan Statistics for the Detection of Outbreaks Involving Common Molecular Subtypes: Using Human Cases of Escherichia coli O157:H7 Provincial PFGE Pattern 8 (National Designation ECXAI.0001) in Alberta as an Example

Molecular typing methods have become a common part of the surveillance of foodborne pathogens. In particular, pulsed-field gel electrophoresis (PFGE) has been used successfully to identify outbreaks of Escherichia coli O157:H7 in humans from a variety of food and environmental sources. However, some PFGE patterns appear commonly in surveillance systems, making it more difficult to distinguish between outbreak and sporadic cases based on molecular data alone. In addition, it is unknown whether these common patterns might have unique epidemiological characteristics reflected in their spatial and temporal distributions. Using E.coli O157:H7 surveillance data from Alberta, collected from 2000 to 2002, we investigated whether E.coli O157:H7 with provincial PFGE pattern 8 (national designation ECXAI.0001) clustered in space, time and space-time relative to other PFGE patterns using the spatial scan statistic. Based on our purely spatial and temporal scans using a Bernoulli model, there did not appear to be strong evidence that isolates of E.coli O157:H7 with provincial PFGE pattern 8 are distributed differently from other PFGE patterns. However, we did identify space-time clusters of isolates with PFGE pattern 8, using a Bernoulli model and a space-time permutation model, which included known outbreaks and potentially unrecognized outbreaks or additional outbreak cases. There were differences between the two models in the space-time clusters identified, which suggests that the use of both models could increase the sensitivity of a quantitative surveillance system for identifying outbreaks involving isolates sharing a common PFGE pattern.

Radiographic Evaluation of the Tegmen in Patients With Superior Semicircular Canal Dehiscence

To determine a radiographic association between superior semicircular canal dehiscence (SSCD) and tegmen dehiscence (TD). Retrospective case-control series. Tertiary referral center. Patients seen between 2003 and 2010 with radiographic SSCD were compared with cochlear implant recipient controls. The tegmen and superior semicircular canal were evaluated on computed tomographic temporal bone scans. If detected, the widest point of the SSCD was measured. The tegmen was graded on a 5-point scale. After analysis, a radiographic TD was defined as any single area of absent tegmen greater than 5 mm, multiple areas of absent tegmen, or evidence of meningocele. Age, sex, and body mass index were also noted. Thirty-eight patients with SSCD and 41 cochlear implant controls were identified. Seventy-six percent (29/38) of patients with unilateral or bilateral SSCD had a radiographic TD on at least 1 side compared with 22% (9/41) of the comparison group. Ninety-four percent (7/18) of patients with bilateral SSCD had a TD on at least 1 side. Patients with SSCD had a 10.2 times (p < 0.001) higher odds of having radiographic TD in either ear compared to the controls. Among patients with any SSCD, for every millimeter increase in the width of dehiscence, the relative risk for any TD increased more than 2-fold (odds ratio, 2.5; p = 0.019). Age, sex, and a body mass index greater than 30 did not confound the association between SSCD and TD. There is a strong radiologic association between SSCD and TD, suggesting a similar etiologic process. The tegmen should be carefully evaluated in patients with SSCD. We have also proposed a new system for radiographically grading the integrity of the tegmen.

Combined Subtemporal–Supralabyrinthine Approach to Geniculate Ganglion for Management of Facial Paralysis in Temporal Bone Fracture

ObjectiveTo investigate the clinical outcomes of facial never decompression via a combined subtemporal–supralabyrinthine approach to geniculate ganglion for management of facial paralysis in temporal bone fracture. MethodsEighteen patients with unilateral facial paresis due to temporal bone fracture were treated between March 2003 and March 2011. Facial function was House–Brackmann(HB) grade III in 6 patients, HB grade V in 9 patients and HB grade VI in 3 patients. The preoperative mean air conduction threshold was 52 dB HL for the 15 cases with longitudinal temporal bone fracture and showed severe sensorineural hearing loss in the 3 cases with transverse temporal bone fracture. Fracture lines were detected in 15 cases on temporal bone axial CT scans and ossicular disruption was determined in 11 cases by virtual CT endoscopy. The geniculate ganglion or the tympanic mastoid segment of the facial nerve showed an irregular morphology on curved planar reformation images of the facial nerve canal. After an intact canal wall mastoido–epitympanectomy, the ossicular chain damage was evaluated. If the ossicular chain was intact, the supralabyrinthine recess was opened by drilling through the cells between the tegmen tympani and ossicular chain. If the ossicular chain was disrupted, the incus was removed to access the supralabyrinthine recess. The geniculate ganglion and the distal labyrinthine segment of the facial nerve were exposed. After completing facial nerve decompression, the dislocated incus was replaced, or a fractured incus was reshaped to bridge the space between the malleus and the stapes. ResultsPronounced ganglion geniculatum swelling was found in 15 cases of longitudinal temporal bone fracture, with greater petrosus nerves damage in 3 cases and bleeding in 5 cases. Disrupted ossicular chains were seen in 11 cases, including dislocated incus resulting in crushing of the horizontal portion of the facial nerve in 3 cases and fracture of the incus long process in 1 case. In 3 cases of transverse fractures, dehiscence on the promontory, semicircular canal or oval window was found. All cases had primary healing with no complication. At follow–ups ranging from 0.5 to 3 years (average 1.2 years) , facial nerve function recovered to HB grade I in 11 cases, II in 5 cases and III in 2 cases. Overall hearing recovery was 33 dB. ConclusionThe clinical outcomes concerning facial nerve function and hearing recovery are satisfactory via a combined subtemporal–supralabyrinthine approach to the geniculate ganglion for facial nerve decompression in temporal bone fracture patients with facial paralysis.

Semi-automatic construction of reference standards for evaluation of image registration

Quantitative evaluation of image registration algorithms is a difficult and under-addressed issue due to the lack of a reference standard in most registration problems. In this work a method is presented whereby detailed reference standard data may be constructed in an efficient semi-automatic fashion. A well-distributed set of n landmarks is detected fully automatically in one scan of a pair to be registered. Using a custom-designed interface, observers define corresponding anatomic locations in the second scan for a specified subset of s of these landmarks. The remaining n-s landmarks are matched fully automatically by a thin-plate-spline based system using the s manual landmark correspondences to model the relationship between the scans. The method is applied to 47 pairs of temporal thoracic CT scans, three pairs of brain MR scans and five thoracic CT datasets with synthetic deformations. Interobserver differences are used to demonstrate the accuracy of the matched points. The utility of the reference standard data as a tool in evaluating registration is shown by the comparison of six sets of registration results on the 47 pairs of thoracic CT data.

Measurement of Stokes parameters of terahertz radiation in terahertz time-domain spectroscopy

We propose a technique for the measurement of Stokes parameters of terahertz radiation in terahertz time-domain spectroscopy (THz-TDS). In this technique, a rotatable wire-grid THz polarizer is placed in front of a two-contact photoconductive THz detector. Stokes parameters can be measured by making two temporal scans corresponding to two angles of the polarizer. We theoretically demonstrate that the two angles can be −45° and 45° for achieving the statistically best measurement accuracy in a single test. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2319–2324, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25450

Enhancement pattern of the normal facial nerve at 3.0 T temporal MRI.

The purpose of this study was to evaluate the enhancement pattern of the normal facial nerve at 3.0 T temporal MRI. We reviewed the medical records of 20 patients and evaluated 40 clinically normal facial nerves demonstrated by 3.0 T temporal MRI. The grade of enhancement of the facial nerve was visually scaled from 0 to 3. The patients comprised 11 men and 9 women, and the mean age was 39.7 years. The reasons for the MRI were sudden hearing loss (11 patients), Méniàre's disease (6) and tinnitus (7). Temporal MR scans were obtained by fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted imaging of the brain; three-dimensional (3D) fast imaging employing steady-state acquisition (FIESTA) images of the temporal bone with a 0.77 mm thickness, and pre-contrast and contrast-enhanced 3D spoiled gradient record acquisition in the steady state (SPGR) of the temporal bone with a 1 mm thickness, were obtained with 3.0 T MR scanning. 40 nerves (100%) were visibly enhanced along at least one segment of the facial nerve. The enhanced segments included the geniculate ganglion (77.5%), tympanic segment (37.5%) and mastoid segment (100%). Even the facial nerve in the internal auditory canal (15%) and labyrinthine segments (5%) showed mild enhancement. The use of high-resolution, high signal-to-noise ratio (with 3 T MRI), thin-section contrast-enhanced 3D SPGR sequences showed enhancement of the normal facial nerve along the whole course of the nerve; however, only mild enhancement was observed in areas associated with acute neuritis, namely the canalicular and labyrinthine segment.

TH‐D‐L100J‐03: An Investigation of the Spatial Resolution Properties of MiniCAT: Flat‐Panel‐Based Volume CT System for Head and Neck Imaging

Purpose: Volume computed tomography (VCT) using flat panel detectors has the capability to provide isotropic high spatial resolution, whereas traditional multislice scanners often exhibit decreased spatial resolution in the axial direction. In many clinical applications including temporal bone imaging, reformatted images reviewed for diagnostic purposes and anisotropic resolution can reduce the clinical utility of such views. We present a spatial resolution investigation of the MiniCAT system, a commercially available flat‐panel‐based VCT system made by Xoran Technologies, Inc. and compare spatial resolution with a traditional multislice CT (MSCT) system (Siemens Sensation 16) using standard acquisition protocols. Method and Materials: We investigate the spatial resolution properties of the flat‐panel‐based VCT and traditional MSCT using line pair phantoms and a comparison of scanned human temporal bones. Graded line pair phantoms are scanned in three orientations to provide resolution measures along each axis (X,Y, and Z). The modulation transfer function (MTF) of the MiniCAT system is computed using conventional techniques. Human temporal bone scans are analyzed qualitatively and clarity of various fine detail features is assessed. Results: We find the spatial resolution of the MiniCAT system to be highly isotropic with an MTF that yields 10% contrast at 17 lp/cm. In the qualitative image quality study we find that fine feature details in the temporal bone like the bone overlying the tympanic section of the facial nerve canal are better resolved using the flat‐panel‐based VCT system than in the traditional MSCT. Conclusion: Flat‐panel‐based VCT can provide finer isotropic resolution than traditional MSCT which may give it an advantage in clinical diagnosis — particularly when looking at small details in oblique views as is common in the diagnosis of otologic pathology. Conflict of Interest: Research sponsored by Xoran Technologies, Inc.

High-Resolution Computed Tomography of Temporal Bone

The purpose of this 4-part series is to illustrate the nuances of temporal bone anatomy using a high-resolution (200 micro isotropic) prototype volume computed tomography (CT) scanner. The normal anatomy in axial and coronal sections is depicted in the first and second parts. In this, the fourth part, and the third part, the structures that are removed and/or altered in 9 different surgical procedures are color coded and inscribed in the same coronal (article IV) and axial (article III) sections. The text stresses clinically important imaging features, including the normal postoperative appearance, and common complications after these operations. The superior resolution of the volume CT images is vital to the comprehensive and accurate representation of these operations. Minuscule intricate structures that are currently only localized in the mind's eye because of the resolution limit of conventional CT are clearly seen on these scans. This enhanced visualization, together with the information presented in the text, should assist in interpreting temporal bone scans, communicating with surgeons, and teaching this complex anatomy.