Axial Reformations Research Articles

Morphological CBCT parameters for an accurate differentiation between nasopalatine duct cyst and the normal nasopalatine canal

BackgroundThe incisive foramen width was a traditional imaging criterion for diagnosing nasopalatine duct (NPD) cysts. Recent CBCT studies demonstrated significant dimensional variations of the nasopalatine canal, which raised questions about the accuracy of this criterion. This study investigated whether nasopalatine canal diameters assessed on CBCT images can accurately differentiate NPD cysts from normal nasopalatine canals.MethodsThe study included 19 patients with NPD cysts (12 (63.2%) males, 7 (36.8%) females, mean age 44.7 ± 13.3), and a control group of 164 patients (72 (43.9%) males, 92 (56.1%) females, mean age 47.25 ± 17.74). CBCT images were retrospectively evaluated. The following nasopalatine canal diameters were measured on reference sagittal, coronal, and axial reformation images: nasal opening anteroposterior (AP) and mediolateral (ML) diameter, oral opening AP (APOO) and ML (MLOO) diameter, nasopalatine canal length, minimum ML (minML) diameter, anterior wall expansion (AWE), nasopalatine canal angle, and the mid-level AP diameter (midAP). All parameters were compared between groups. Discriminant functional analysis (DFA) was applied to detect CBCT parameters that best differentiate the NPD cyst from the normal canal.ResultsPatients with NPD cyst had significantly greater values of APOO (7.06 ± 2.09 vs. 5.61 ± 1.70), MLOO (6.89 ± 2.95 vs. 3.48 ± 1.24), minML (2.88 ± 1.53 vs. 2.25 ± 1.09), AWE (2.15 ± 0.65 vs. 0.41 ± 0.67), and midAP (4.58 ± 1.61 vs. 2.48 ± 0.96). DFA showed MLOO, AWE, and midAP as the most accurate in distinguishing NPD cyst from the normal canal. When combined in the discriminant function equation X = 0.390·MLOO + 1.010·AWE + 0.288·midAP (cut score 1.669), the differentiation can be performed with a sensitivity and specificity of 98.8% and 76.9%, respectively.ConclusionNPD cysts can be accurately distinguished from the normal nasopalatine canal by measuring MLOO, AWE, and midAP diameter on CBCT images.

Visualization of meniscus with 3D axial reconstructions

PurposeTo visualize the meniscus of the knee joint in the axial plane and identify injuries that cannot be visualized using conventional sequences. MethodsTwo hundred and two subjects underwent an improvised 3-Dimensional Proton Density Fat Saturation (3D-PD FS) Magnetic Resonance (MR) sequence on their meniscus. The transverse images were reconstructed and examined. Fifty-three of the subjects had a healthy meniscus and their images were used as part of a qualitative evaluation to verify that all parts of the meniscus were properly visualized. The evaluation was based on a four-level scale indicating the visualization of meniscal parts. The same evaluation was also performed on the 149 subjects with meniscal pathologies. Another qualitative evaluation was performed on all subjects concerning five image characteristics based on a five-level scale. Finally, images from 20 patients with meniscal pathologies were compared with arthroscopic images visualizing meniscal tears. ResultsIn all subjects, all parts of the meniscus were clearly visualized. The axial reformats provided ideal imaging of the meniscus, yielding high total image quality, satisfactory smoothing and sharpening, fewer artifacts, and successful fat saturation. The findings of the MR images from the 20 subjects with meniscal pathologies, concerning the topography of meniscal tears coincided at 100% with their arthroscopic findings. ConclusionThe use of the improvised 3D-PD FS sequence provides the possibility of axial reconstruction with a better depiction of the meniscus. These images can accurately illustrate the range of the meniscus and any meniscal tears along with their exact location with high image quality.

DIAGNOSTICS OF DICHOTOMY TEETH IN ORTHODONTIC RELAPSE

Aim: increasing the effectiveness of diagnosis and further orthodontic-surgical treatment of various clinical forms of hyperdontia (supernumerary teeth) and preventing recurrence with the use of cone-ray computer tomography data in orthodontic practice. Materials and methods. The clinical case of patient (born in 2004) treatment is presented, with severe hyperdontia and retention of teeth that had little effect on the formation of the general configuration of occlusion. The patient's examination and treatment was carried out with the assistance of clinical, anthropometric and radiological data. The clinical method was to examine the patient and formulate a plan for further orthodontic therapy. The radiological method consisted of data analysis of cefalometry by Bjork, Steiner using a computer program and conducting a survey using a cone-ray computer tomography, followed by the use of these data in diagnosis and orthodontic treatment. Results. Following the clinical and radiological methods of examination and subsequent orthodontic surgery, the corresponding end results were obtained: 1. The localization and topography of supernumerary teeth as the causes of relapse of pathology with the help of data obtained with the help of CBCT. 2. Radiographic picture reflected on the sagital and axial re-formats of tomograms for the diagnosis of supernumerary teeth, is more informative than diagnostics by standard diagnostic protocols. 3. After analysis of the study data, a more meaningful protocol of surgical intervention is prescribed. 4. Implementation of the results of modern diagnostics significantly influenced on the final result of orthodontic treatment. Conclusions. Thus, in the process of corresponding work installed: – the availability of computer tomography data is crucial for objective and qualitative diagnosis and treatment of hypertension. – the general level of diagnostics during the intervention is significantly increased.

Modified Friedman technique: a new proposed method of measuring glenoid version in the setting of glenohumeral dysplasia.

Glenoid version angles are measured to objectively follow changes related to glenohumeral dysplasia in the setting of brachial plexus birth palsy. Measuring glenoid version on cross-sectional imaging was initially described by Friedman et al. in 1992. Recent literature for non-dysplastic shoulders advocates time-consuming reconstructions and reformations for an accurate assessment of glenoid version. To compare Friedman's original method for measuring glenoid version to a novel technique we developed ("modified Friedman") with the reference standard of true axial reformations. With institutional review board approval, we retrospectively examined 30 normal and dysplastic shoulders obtained from magnetic resonance imaging examinations of 30 patients with an established diagnosis of brachial plexus birth palsy between January 2012 and September 2017. Four pediatric radiologists performed glenoid version measurements using Friedman's method, the modified Friedman method and a previously described true axial reformation method. The modified Friedman technique better accounts for scapular positioning by selecting a reference point related to the acromion-scapular body interface. Inter-rater reliability and inter-method agreement were assessed using intraclass correlation, paired t-tests and mixed linear model analysis. Equivalence tests between methods were performed per reader. Glenoid version measurements were significantly different when comparing Friedman's method to true axial reformations in normal (-10.8±5.7° [mean±standard deviation] vs. -8.8±5.3°; P≤0.001) and dysplastic shoulders (-34.6±17.7° vs. -28.1±17.5°; P≤0.001). Glenoid version measurements were not significantly different when comparing the modified Friedman's method to true axial reformations in normal (-6.3±5.8° vs. -8.8±5.3°; P=0.06) and dysplastic shoulders (-29.0±18.3° vs. -28.1±17.5°; P=0.06). Friedman's method was not equivalent to true axial reformations for measurements in dysplastic shoulders for all readers (P=0.68, 0.81, 0.86, 0.99); the modified Friedman method was equivalent to of true axial reformations for measurements in dysplastic shoulders for 3 of 4 readers (P≤0.001, P≤0.001, P≤0.001, P=0.10). In glenohumeral dysplasia, the modified Friedman method and post-processed true axial reformations provide statistically similar and reproducible values. We propose that our modified Friedman technique can be performed in lieu of post-processed true axial reformations to generate glenoid version measurements.

Is Increased Acetabular Cartilage or Fossa Size Associated With Pincer Femoroacetabular Impingement?

Surgical treatment for pincer femoroacetabular impingement (FAI) of the hip remains controversial, between trimming the prominent acetabular rim and reverse periacetabular osteotomy (PAO) that reorients the acetabulum. However, rim trimming may decrease articular surface size to a critical threshold where increased joint contact forces lead to joint degeneration. Therefore, knowledge of how much acetabular articular cartilage is available for resection is important when evaluating between the two surgical options. In addition, it remains unclear whether the acetabulum rim in pincer FAI is a prominent rim because of increased cartilage size or increased fossa size. We used reformatted MR and CT data to establish linear length dimensions of the lunate cartilage and cotyloid fossa in normal, dysplastic, and deep acetabula. We reviewed the last 200 hips undergoing PAO, reverse PAO, and surgical dislocation for acetabular rim trimming at one institution. We compared MR images of symptomatic hips with acetabular dysplasia (20 hips), pincer FAI (29 hips), and CT scans of asymptomatic hips from patients who underwent CT scans for reasons other than hip pain (20 hips). These hips were chosen sequentially from the underlying pool of 200 potential subjects to identify the first 10 male and the first 10 female hips in each group that met inclusion criteria. As a result of low numbers, we included all hips that had undergone reverse PAO and met inclusion criteria. Cartilage width was measured medially from the cotyloid fossa to the lateral labrochondral junction. Cotyloid fossa linear height was measured from superior to inferior and cotyloid fossa width was measured from anterior to posterior. Superior lunate cartilage width (SLCW) and cotyloid fossa height (CFH) were measured on MR and CT oblique coronal reformats; anterior lunate cartilage width (ALCW), posterior lunate cartilage width (PLCW), and cotyloid fossa width (CFW) were measured on MR and CT oblique axial reformats. Cohorts were compared using multivariate analysis of variance with Bonferroni's adjustment for multiple comparisons. Compared with control acetabula, dysplastic acetabula had smaller SLCW (2.08 ± 0.29 mm versus 2.63 ± 0.42 mm, mean difference = -0.55 mm; 95% confidence interval [CI] = -0.83 to -0.27; p < 0.01), ALCW (1.20 ± 0.34 mm versus 1.64 ± 0.21 mm, mean difference = -0.44 mm; 95% CI = -0.70 to -0.18; p = 0.00), CFH (2.84 ± 0.37 mm versus 3.42 ± 0.57 mm, mean difference = -0.59 mm; 95% CI = -0.96 to -0.21; p < 0.01), and CFW (1.98 ± 0.50 mm versus 2.77 ± 0.33 mm, mean difference = -0.80 mm; 95% CI = -1.16 to -0.42; p < 0.0001). Based on the results, we identified two subtypes of deep acetabula. Compared with controls, deep subtype 1 had normal CFH and CFW but increased ALCW (2.09 ± 0.42 mm versus 1.64 ± 0.21 mm; p < 0.001) and PLCW (2.32 ± 0.36 mm versus 2.00 ± 0.32 mm; p = 0.04). Compared with controls, deep subtype 2 had increased CFH (4.37 ± 0.51 mm versus 3.42 ± 0.57 mm; p < 0.01) and CFW (2.76 ± 0.54 mm versus 2.77 ± 0.33 mm; p = 1.0) but smaller SCLW (2.12 ± 0.40 mm versus 2.63 ± 0.42 mm; p < 0.01). Deep acetabula have two distinct morphologies: subtype 1 with increased anterior and posterior cartilage lengths and subtype 2 with a larger fossa in height and width and smaller superior cartilage length. In patients with deep subtype 1 hips that have increased anterior and posterior cartilage widths, rim trimming to create an articular surface of normal size may be reasonable. However, for patients with deep subtype 2 hips that have large fossas but do not have increased cartilage widths, we propose that a reverse PAO that reorients yet preserves the size of the articular surface may be more promising. However, these theories will need to be validated in well-controlled clinical studies.

Influence of model based iterative reconstruction algorithm on image quality of multiplanar reformations in reduced dose chest CT.

BackgroundModel-based iterative reconstruction (MBIR) reduces image noise and improves image quality (IQ) but its influence on post-processing tools including maximal intensity projection (MIP) and minimal intensity projection (mIP) remains unknown.PurposeTo evaluate the influence on IQ of MBIR on native, mIP, MIP axial and coronal reformats of reduced dose computed tomography (RD-CT) chest acquisition.Material and MethodsRaw data of 50 patients, who underwent a standard dose CT (SD-CT) and a follow-up RD-CT with a CT dose index (CTDI) of 2–3 mGy, were reconstructed by MBIR and FBP. Native slices, 4-mm-thick MIP, and 3-mm-thick mIP axial and coronal reformats were generated. The relative IQ, subjective IQ, image noise, and number of artifacts were determined in order to compare different reconstructions of RD-CT with reference SD-CT.ResultsThe lowest noise was observed with MBIR. RD-CT reconstructed by MBIR exhibited the best relative and subjective IQ on coronal view regardless of the post-processing tool. MBIR generated the lowest rate of artefacts on coronal mIP/MIP reformats and the highest one on axial reformats, mainly represented by distortions and stairsteps artifacts.ConclusionThe MBIR algorithm reduces image noise but generates more artifacts than FBP on axial mIP and MIP reformats of RD-CT. Conversely, it significantly improves IQ on coronal views, without increasing artifacts, regardless of the post-processing technique.

Evaluation of a new mid-scala cochlear implant electrode using microcomputed tomography.

To investigate electrode position, depth of insertion, and electrode contact using an electrode array with a mid-scala design following round window (RW) and cochleostomy insertion. Eight fresh-frozen cadaveric bones were implanted; half via a RW approach and half through an anteroinferior cochleostomy using a styleted mid-scala electrode design. Microcomputed tomography was used to acquire oblique coronal and oblique axial reformations. Individual electrode positions along each array, insertional depth, and electrode contact were determined using National Institutes of Health Image J software. All electrodes were inserted without significant resistance. The average angular depth of insertion was 436.5° for the RW group and 422.7° for the cochleostomy group. All electrodes acquired a perimodiolar position in the proximal segment and a lateral wall position at the basal turn, regardless of approach. Electrodes distal to the basal turn demonstrated a variable location, with 78% mid scala. One cochleostomy array fractured through the interscalar partition (ISP), acquiring a scala vestibuli position. The odds ratio for either abutting the modiolus, ISP, lateral wall or floor, or fracturing through the ISP were 2.7 times more likely following a cochleostomy insertion (P = .032). The styleted mid-scala electrode design acquires a proximal perimodiolar position, a lateral wall location, as it traverses the basal turn, and most commonly a mid-scala position in the distal array. Interscalar excursion occurred in one of the cochleostomy insertions. Cochleostomy insertion is more likely to result in ultimate final electrode position adjacent to critical intracochlear structures. NA.

Non-contrast diffusion weighted imaging for the assessment of knee synovitis: a comparative study against contrast-enhanced MRI

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S252 446 NON-CONTRAST DIFFUSION WEIGHTED IMAGING FOR THE ASSESSMENT OF KNEE SYNOVITIS: A COMPARATIVE STUDY AGAINST CONTRAST-ENHANCED MRI E.H. Oei yz, E.J. McWalter y, B. Sveinsson y, M.T. Alley y, B.A. Hargreaves y, G.E. Gold y. y Stanford Univ., Stanford, CA; z Erasmus MC, Rotterdam, Netherlands Purpose: Over recent years, attention has turned to the importance of synovitis in osteoarthritis (OA). Synovitis, characterized by thickening of the synovial membrane and joint effusion, is believed to play a significant role in the pathogenesis of OA, and is regarded as a potential target for novel treatment strategies. The current reference standard for imaging of synovitis is contrast enhanced magnetic resonance imaging (CE MRI) which is associated with higher costs, elevated risks, and prolonged scan times compared to non-contrast enhanced MRI exams. A modified version of the novel three-dimensional (3D) double echo steady state (DESS) sequence can be exploited to image synovitis without contrast agents by increasing diffusion weighting and thereby improving contrast between the synovium and the joint fluid. The purpose of this study was to compare DESS with contrast-enhanced MRI for knee synovitis assessment. Methods: Nine individuals with symptomatic inflammatory arthritis of the knee underwent a 3.0T MRI examination. The protocol consisted of routine clinical sequences followed by the modified 3D DESS sequence (sagittal acquisition with axial reformats; matrix 256 256; field of view 16 cm; slice thickness 3 mm; acquisition time 5:00 minutes) acquired with a high diffusion gradient (10 cycles/voxel) and contrastenhanced (CE) T1-weighted imaging (sagittal and axial; matrix 384 256; slice thickness 3 mm; acquisition time 4:30 minutes). DESS and CE MRI images were scored independently and in random order by a blinded musculoskeletal radiologist. The presence and severity of synovitis was graded at 11 joint sites and a whole-joint sum score was calculated according to the recently published semiquantitative scoring system by Guermazi et al. Diagnostic performance statistics were calculated on the site and patient levels andwhole-joint synovitis scores of DESS were correlated with those of CE MRI (reference standard). Results: Compared to CE MRI, DESS showed good to excellent diagnostic performance for the detection of synovitis of any severity (sensitivity, specificity, and agreement of 81, 85, and 83%, respectively, on site level; and 100%, 100%, and 100%, respectively, on patient level) (see Fig. 1 for illustrative example). DESS, however, systematically underestimated synovitis severity compared to CE MRI (74% absolute score agreement analyzed by site). Excellent correlation was found between summed whole-joint synovitis scores of DESS and CE MRI (Pearson’s correlation coefficient 0.87 (p 1⁄4 0.002), intra-class correlation coefficient 0.86 (95%CI 0.49–0.97)) (Fig. 2). Conclusions: Our results suggest that diffusion weighted imaging with a modified 3D double echo steady state (DESS) sequence acquired with high diffusion gradient is a promising MRI technique for the reliable diagnosis and (semiquantitative) grading of knee synovitis without the need for contrast agents. DESS may be a useful sequence to include in MRI protocols for the comprehensive assessment of OA with reduced costs, risks, and scan time compared to contrast enhanced sequences. Fig. 1. Severe degree of synovitis visualized in the paraand suprapatellar, intercondylar, and posterior cruciate ligament regions (arrows) on CE MRI (left) and DESS (right). Fig. 2. Correlation plot of summed whole-joint synovitis scores of DESS vs. CE MRI. 447 QUANTITATIVE T1r, T2 AND T2* MAPPING OF ARTICULAR CARTILAGE CHANGES IN A RAT MODEL OF OSTEOARTHRITIS USING IN VIVO HIGH-RESOLUTION MAGNETIC RESONANCE IMAGING G. Mohan y, G. Melkus y, K. Subburaj y, S. Magnitsky y, A. Dang z, N.E. Lane x, S. Majumdar y. yDept. of Radiology and BioMed. Imaging, Univ. of California, San Francisco, San Francisco, CA; zDept. of Orthopaedic Surgery, Univ. of California, San Francisco, San Francisco, CA; xDept. of Internal Med., Univ. of California at Davis Med. Ctr., Sacramento, Sacramento, CA Purpose:Magnetic resonance imaging (MRI) has become a key imaging tool in osteoarthritis (OA) research due to its ability to visualize bone as well as soft tissues such as cartilage, ligaments, menisci and synovium. Cartilage matrix degradation is a characteristic feature of OA and compositional MRI can assess early biochemical (proteoglycan and collagen content) and structural changes in the cartilage. Quantitative MRI techniques such as T1r, T2 and T2* were shown to provide accurate

Comparison of 3D multi-echo gradient-echo and 2D T2* MR sequences for the detection of arterial thrombus in patients with acute stroke

We compared a multi-echo gradient-echo magnetic resonance sequence (susceptibility-weighted angiography [SWAN]) with the T2* sequence for the detection of an arterial thrombus in acute ischaemic stroke. Seventy-four consecutive patients with acute ischaemic stroke were included. Proximal arterial occlusions were diagnosed using time-of-flight (TOF) magnetic resonance angiography (MRA). Two-dimensional (2D) axial reformats from 3D SWAN were generated to match with 2D T2* images. For arterial thrombus detection, each set of MR images (T2*, 2D SWAN reformats and 3D multiplanar SWAN images) was examined independently and separately by three observers who assigned the images to one of three categories: (0) absence of thrombus, (1) uncertain thrombus, (2) certain thrombus. Agreement and diagnostic accuracy were calculated. Twenty-four proximal arterial occlusions involving the anterior (n = 20) or posterior (n = 4) circulation were found. Inter-observer agreement was moderate using T2* images (κ = 0.58), good using 2D SWAN reformats (κ = 0.83) and excellent using multiplanar SWAN images (κ = 0.90). For the diagnosis of thrombus, T2* images were 54% sensitive and 86% specific, 2D SWAN reformats were 83% sensitive and 94% specific and SWAN multiplanar analysis was 96% sensitive and 100% specific. Three-dimensional SWAN sequence improves the detection of arterial thrombus in patients with acute ischaemic stroke in comparison with the 2D T2* sequence. • Multi-echo gradient-echo MR (e.g. susceptibility-weighted angiograph, [SWAN]) is increasingly used in neuroradiology. • Compared with conventional T2* sequences, SWAN improves detection of arterial thrombus. • Multiplanar SWAN analysis had the best diagnostic performance for arterial thrombus detection. • Sensitivity was 96% and specificity 100%. • Findings support combination of time-of-flight and susceptibility effects in suspected acute stroke.

Accuracy of Postcontrast 3D Turbo Spin-Echo MR Sequence for the Detection of Enhanced Inflammatory Lesions in Patients with Multiple Sclerosis

Therapeutic strategies for patients with MS partly rely on contrast-enhanced MR imaging. Our aim was to assess the diagnostic performance of 3D turbo spin-echo MR imaging with variable refocusing flip angles at 3T for the detection of enhanced inflammatory lesions in patients with multiple sclerosis. Fifty-six patients with MS were prospectively investigated by using postcontrast T1-weighted axial 2D spin-echo and 3D TSE MR images. The order in which both sequences were performed was randomized. Axial reformats from 3D T1 TSE were generated to match the 2D spin-echo images. The reference standard was defined by using clinical data and all MR images available. Three separate sets of MR images (2D spin-echo images, axial reformats, and multiplanar images from 3D TSE sequences) were examined in a blinded fashion by 2 neuroradiologists separately for the detection of enhanced MS lesions. Image artifacts and contrast were evaluated. No artifacts related to vascular pulsation were observed on 3D TSE images, whereas image artifacts were demonstrated on 2D spin-echo images in 41 patients. One hundred twelve enhanced MS lesions were identified in 19 patients. Sixty-four lesions were correctly diagnosed by using 2D spin-echo images; 90, by using 3D TSE axial reformatted views; and 106, by using multiplanar analysis of the 3D TSE sequence. Multiplanar analysis was 94.7% sensitive and 100% specific for the diagnosis of patients with at least 1 enhanced lesion. Contrast of enhanced MS lesions was significantly improved by using the 3D TSE sequence (P < .011). The 3D TSE sequence with multiplanar analysis is a useful tool for the detection of enhanced MS lesions.

CT Perfusion in Acute Stroke: Added Value or Waste of Time?

HomeStrokeVol. 44, No. 9CT Perfusion in Acute Stroke: Added Value or Waste of Time? Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBCT Perfusion in Acute Stroke: Added Value or Waste of Time? Manas Sharma, MBBS, MD and David M. Pelz, MD, FRCPC Manas SharmaManas Sharma Department of Medical Imaging, Western University, London, Ontario, Canada Search for more papers by this author and David M. PelzDavid M. Pelz Department of Medical Imaging, Western University, London, Ontario, Canada Search for more papers by this author Originally published15 Aug 2013https://doi.org/10.1161/STROKEAHA.113.002355Stroke. 2013;44:e115Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: January 1, 2013: Previous Version 1 To the Editor:We read with interest the 2 recent articles by Zhu et al1,2 regarding the usefulness of computed tomography perfusion (CTP) studies for predicting outcomes in acute stroke patients. We are puzzled by the analysis of data from the same group of patients being interpreted in such diametrically opposite ways by the same authors.In the first article,1 the authors conclude that a cerebral blood flow/cerebral blood volume mismatch or demonstration of an ischemic penumbra on CTP maps alone cannot predict functional outcome unless recanalization status is also considered. If recanalization recurs, penumbra is a positive outcome predictor or vice versa. As the authors state, it is impossible to know the recanalization status at the time of treatment decision. So CTP, by implication, is of little predictive use by itself.In the second article,2 a mere 35 pages later, the authors state that the CTP-demonstrated penumbra constitutes unique information and is an independent predictor of 90-day modified Rankin Score. Although they mention that CTP data are only a “hallmark” of positive outcome if there is recanalization, they omit any reference to their own work showing its irrelevance. Therefore, the CTP component of an acute stroke workup now adds value. This is confusing and suggests that the authors themselves have no clear understanding of the role of CTP in acute stroke imaging.Despite the authors’ assertion that CT angiography is not useful for assessing collateral status, the references used are outdated. Many centers are questioning the use of CTP and using noncontrast CT and CT angiography source images to assess the penumbra, guide treatment, and predict outcomes.3,4 Studies have shown that CT angiography source images (3- to 4-mm axial reformats of the raw data) in modern scanners can distinguish penumbra from infarct core and that the postcontrast CT can delineate the core infarct,3 thus essentially providing the same data as CTP. This information is obtained quickly and needs no additional time or computer expertise. Many stroke centers are eliminating CTP completely, given the extra time, radiation, and processing time for questionable benefit.The usefulness of CTP in acute stroke imaging is still uncertain, and more study is required. Confusing interpretations of the same data with contradictory conclusions do nothing to clarify this question.Manas Sharma, MBBS, MDDavid M. Pelz, MD, FRCPCDepartment of Medical ImagingWestern UniversityLondon, Ontario, CanadaDisclosuresNone.FootnotesStroke welcomes Letters to the Editor and will publish them, if suitable, as space permits. Letters must reference a Stroke published-ahead-of-print article or an article printed within the past 3 weeks. The maximum length is 750 words including no more than 5 references and 3 authors. Please submit letters typed double-spaced. Letters may be shortened or edited.

Imaging of the wrist at 1.5 tesla using isotropic three‐dimensional fast spin echo cube

To compare three-dimensional fast spin echo Cube (3D-FSE-Cube) with conventional 2D-FSE in MR imaging of the wrist. The wrists of 10 volunteers were imaged in a 1.5 Tesla MRI scanner using an eight-channel wrist coil. The 3D-FSE-Cube images were acquired in the coronal plane with 0.5-mm isotropic resolution. The 2D-FSE images were acquired in both coronal and axial planes for comparison. An ROI was placed in fluid, cartilage, and muscle for SNR analysis. Comparable coronal and axial images were selected for each sequence, and paired images were randomized and graded for blurring, artifact, anatomic details, and overall image quality by three blinded musculoskeletal radiologists. SNR of fluid, cartilage and muscle at prescribed locations were higher using 3D-FSE-Cube, without reaching statistical significance. Fluid-cartilage CNR was also higher with 3D-FSE-Cube, but not statistically significant. Blurring, artifact, anatomic details, and overall image quality were significantly better on coronal 3D-FSE-Cube images (P < 0.001), but significantly better on axial 2D-FSE images compared with axial 3D-FSE-Cube reformats (P < 0.01). Isotropic data from 3D-FSE-Cube allows reformations in arbitrary scan planes, which may make multiple 2D acquisitions unnecessary, and improve depiction of complex wrist anatomy. However, axial reformations suffer from blurring, likely due to T2 decay during the long echo train, limiting overall image quality in this plane.

Evaluation of Coronary Stents With 64-MDCT: In Vitro Comparison of Scanners From Four Vendors

The purpose of this study was to compare 64-MDCT scanners from four vendors in the in vitro evaluation of coronary artery stents. Twelve coronary artery stents (nominal outer diameter, 2.5-5.0 mm) oriented in the z-axis were placed in a combined cardiac-chest phantom and imaged with 64-MDCT scanners from four vendors. Quantitative image quality parameters, including artificial in-stent luminal narrowing, image noise, and artificial in-stent luminal attenuation were measured on longitudinal and axial reformations. Imaging of stents with a luminal diameter of 3 mm or less and that of stents with a diameter greater than 3 mm also were compared. Artificial in-stent luminal narrowing was not different among the four vendors (range, 37-42%) on longitudinal reformations. Image noise inside the stent was significantly greater for one vendor (Siemens Healthcare; SD, 48 HU) than for the others (SD range, 21-26 HU) on longitudinal but not on axial images. For the same vendor, artificial in-stent luminal attenuation was significantly lower than for the other vendors. For all vendors, image noise inside the stent was significantly greater on axial than on longitudinal reformations (p < 0.001), and artificial luminal attenuation was significantly greater for all but one vendor (GE Healthcare). Stents 3 mm and narrower had significantly greater artificial luminal narrowing and artificial luminal attenuation (p < 0.05) than those with a diameter greater than 3 mm. For longitudinal reformations, scanners from the four leading vendors do not differ in artificial luminal narrowing, but there are differences in artificial luminal attenuation and image noise. The quality of images of the in-stent lumen is better on longitudinal reformations and for stents with a diameter greater than 3 mm. Except for image noise, differences between axial and longitudinal reformations are vendor specific.

Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen's kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences.

Comparison of 45° Oblique Reformats with Axial Reformats in CT Evaluation of the Vestibular Aqueduct

Measurement of the vestibular aqueduct on CT scans of the temporal bone is important for the detection of large vestibular aqueduct syndrome; typically this is done in the axial plane. We sought to determine the usefulness of reformats performed in the 45 degrees oblique plane for evaluating the vestibular aqueduct. In addition, we provide reference measurements for the vestibular aqueduct in the 45 degrees oblique plane. MATERIALS AD METHODS: We selected 15 subjects referred for reasons other than sensorineural hearing loss, and without radiographic evidence of abnormality of the inner ear. Two neuroradiologists independently evaluated both axial and 45 degrees oblique images for ease in visualizing the vestibular aqueduct. Then, one of the readers (B.O.) performed reference measurements of the diameter at the mouth and midpoint of the aqueduct. Combining the results of both observers, we judged 82% of vestibular aqueducts as well-defined or easily traced on 45 degrees oblique views, whereas we judged only 55% as well-defined or easily traced on axial views. The difference in the degrees of visualization between the 45 degrees oblique and axial reformats was significant for observer 1 (P =.022) and observer 2 (P =.001). Intraobserver agreement about the visibility of the aqueduct was higher on the 45 degrees oblique than the axial views: (kappa = 0.682, SE = 0.171) for 45 degrees oblique reformats; (kappa = 0.480, SE = 0.145) for axial reformats. On the 45 degrees oblique reformats, the mean external aperture dimension of the vestibular aqueduct was measured as 0.616 +/- 0.133 mm, and the postisthmic segment had a mean width of 0.482 +/- 0.099 mm. The 45 degrees oblique plane gives a more reliable depiction of the vestibular aqueduct than the axial plane in CT evaluation of the temporal bone. This technique can be useful in cases of borderline enlargement of the vestibular aqueduct.

Clinical Evaluation of a Computer-Aided Diagnosis (CAD) Prototype for the Detection of Pulmonary Embolism

To evaluate the performance of a prototype computer-aided diagnosis (CAD) tool using artificial intelligence techniques for the detection of pulmonary embolism (PE) and the possible benefit for general radiologists. Forty multidetector row computed tomography datasets (16/64- channel scanner) using 100 kVp, 100 mAs effective/slice, and 1-mm axial reformats in a low-frequency reconstruction kernel were evaluated. A total of 80 mL iodinated contrast material was injected at a flow rate of 5 mL/seconds. Primarily, six general radiologists marked any PE using a commercially available lung evaluation software with simultaneous, automatic processing by CAD in the background. An expert panel consisting of two chest radiologists analyzed all PE marks from the readers and CAD, also searching for additional finding primarily missed by both, forming the ground truth. The ground truth consisted of 212 emboli. Of these, 65 (31%) were centrally and 147 (69%) were peripherally located. The readers detected 157/212 emboli (74%) leading to a sensitivity of 97% (63/65) for central and 70% (103/147) for peripheral emboli with 9 false-positive findings. CAD detected 168/212 emboli (79%), reaching a sensitivity of 74% for central (48/65) and 82%(120/147) for peripheral emboli. A total of 154 CAD candidates were considered as false positives, yielding an average of 3.85 false positives/case. The CAD software showed a sensitivity comparable to that of the general radiologists, but with more false positives. CAD detection of findings incremental to the radiologists suggests benefit when used as a second reader. Future versions of CAD have the potential to further increase clinical benefit by improving sensitivity and reducing false marks.

Computed tomography demonstrates short axial globe length in cases with idiopathic intracranial hypertension

Patients with idiopathic intracranial hypertension (IIH) and papilledema have been anecdotally found to demonstrate relatively short axial lengths on ultrasound A-scans. This explains the hyperopic shift sometimes present in these patients. In this study, the authors systematically investigated globe shape in cases with IIH using computed tomography. Computed tomographic 0.625-mm sections of 10 cases with IIH and 10 control subjects were reformatted on a workstation. Globe lengths and widths were measured from axial reformats. Globe lengths and heights were measured from oblique sagittal reformats. Two masked observers took all the measurements. The authors observed that the mean axial lengths of the globes of cases with IIH were significantly shorter than those of controls (t test for independent samples, P < .001). Both observers also found globe height to be significantly greater than globe length in oblique sagittal sections of cases with IIH compared with control subjects (Mann-Whitney U tests, P < .01). The difference between length and width in axial sections was not different between cases with IIH and control subjects. Using a critical cutoff of 0.6-mm difference between globe height and length in oblique sagittal sections returned a sensitivity of 0.75 and a specificity of 0.75 for IIH detection from both right and left eyes. The authors conclude that there are considerable differences in globe shape and axial length between cases with IIH and control subjects. However, the differences in globe shape manifest significantly only in oblique sagittal sections.—Valérie Biousse

Computed Tomography Demonstrates Short Axial Globe Length in Cases with Idiopathic Intracranial Hypertension

Cases with idiopathic intracranial hypertension (IIH) have been anecdotally found to demonstrate relatively short axial lengths on ultrasound A-scans. This finding has not been rigorously documented. We therefore systematically investigated globe shape in these cases using computed tomography. Computed tomographic 0.625-mm sections of 10 cases with IIH and 10 control subjects were reformatted on a workstation. Globe lengths and widths were measured from axial reformats. Globe lengths and heights were measured from oblique sagittal reformats. Two masked observers took all the measurements. The mean axial lengths of the globes of cases with IIH were significantly shorter than those of controls (t test for independent samples, P<0.001). Both observers also found globe height to be significantly greater than globe length in oblique sagittal sections of cases with IIH compared with control subjects (Mann-Whitney U tests, P<0.01). The difference between length and width in axial sections was not different between cases with IIH and control subjects. Using a critical cutoff of 0.6-mm difference between globe height and length in oblique sagittal sections returned a sensitivity of 0.75 and a specificity of 0.75 for IIH detection from both right and left eyes. There are significant differences in globe shape and axial length between cases with IIH and control subjects. The differences in globe shape manifest significantly only in oblique sagittal sections. This imaging sign could be a useful marker for subclinical IIH.

Intraoperative Three-Dimensional Imaging With a Motorized Mobile C-Arm (SIREMOBIL ISO-C-3D) in Foot and Ankle Trauma Care

The aim of the study was to assess the feasibility and benefit of the intraoperative use of a mobile C-arm with 3-dimensional imaging (ISO-C-3D). Prospective consecutive clinical study. University hospital, level I trauma center. The ISO-C-3D was used for intraoperative visualization in foot and ankle trauma care. Conventional C-arms were used to judge the reduction and implant position before the ISO-C-3D was used. Time spent, changes resulting from use of the ISO-C-3D, and surgeons' ratings (visual analogue scale, 0-10 points) were recorded. Between January 1, 2003 and March 15, 2004, the ISO-C-3D was used in 62 cases (factures: pilon, n = 1; Weber-C ankles, n = 7; isolated dorsal Volkmann, n = 1; talus, n = 3; calcaneus, n = 20; navicular, n = 1; cuboid, n = 1; Lisfranc fracture-dislocation, n = 6; hindfoot arthrodesis with or without correction, n = 12). On average, the operation was interrupted for 440 seconds (range 330-700); 120 seconds, on average, for the ISO-C-3D scan and 210 seconds, on average, for evaluation of the images by the surgeon. In 39% of the cases (24 of 62), the reduction and/or implant position was corrected during the same procedure after the ISO-C-3D scan. The ratings of the 8 surgeons who used the ISO-C-3D were 9.2(5.2-10) for feasibility, 9.5 (6.1-10) for accuracy, and 8.2 (4.5-10) for clinical benefit. Intraoperative 3-dimensional visualization with the ISO-C-3D can provide useful information in foot and ankle trauma care that cannot be obtained from plain films or conventional C-arms. During the same procedure, after conventional C-arm scans judged the positioning to be correct and an ISO-C-3D scan was done, the reduction and/or implant position was corrected in 39% of the cases in this study, although not unnecessarily prolonging the operation. The ISO-C-3D appears to be most helpful in procedures with a closed reduction and internal fixation, and/or when axial reformations provide information that is not possible to obtain with a conventional C-arm and/or direct visualization during open reduction and internal fixation.

Rational CT diagnosis before operations on the paranasal sinuses

Movement or metal artefacts as well as the relatively high radiation exposure of both the axial and the coronal scan are disadvantages of computed tomography. A single spiral CT scan with a secondary reformation replacing the second CT scan might solve these problems. The goal of this project was to compare the diagnostic value of primary spiral CT scans of paranasal sinuses with secondary reformations. These were evaluated by ENT surgeons as well as radiologists. We performed axial and coronal spiral-CT's of paranasal sinuses in 80 patients. The secondary coronal and axial reformations were calculated with 2 mm image sections. Although a reduced resolution was observed in the secondary reformations, this did not compromise the detection of important anatomical features. Image deterioration due to artifacts was significantly reduced.