Coronal Orientation Research Articles

Imaging hemidiaphragmatic injury

The supine chest radiograph is the initial and most commonly performed imaging study to evaluate the thorax after trauma. Whenever the chest radiograph is equivocal or suspicious for acute diaphragmatic injury (DI), computed tomography (CT) is usually the next study of choice since it is both generally available and often used to examine other body regions in the patient after trauma. CT is usually diagnostic, particularly if supplemented by multiplanar reformation (MPR) obtained using thin-slice axial scanning and overlapping images for reformations. Magnetic resonance imaging (MRI) is potentially useful to assess the diaphragm if CT findings are indeterminate and the patient is stable enough to have the procedure. Simple T1-weighted spin-echo images in the sagittal and coronal orientation are usually sufficient to establish or exclude DI. This article reviews imaging modalities and strategies for diagnosing DI from blunt trauma.

Value of Single-Dose Contrast-Enhanced Magnetic Resonance Angiography Versus Intraarterial Digital Subtraction Angiography in Therapy Indications in Abdominal and Iliac Arteries

The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committe was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30 degrees , field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses > or = 50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.

Morphometric analyses of the cervical superior facets and implications for facet dislocation

The articular facets of the cervical spine have been well addressed; however, little information is available on the relationship of the superior facets of the cervical spine to traumatic dislocation in the literature. Morphometric analyses of the superior facets of 30 dried cervical spines from C3 to C7 were performed to determine any morphological differences. The angle of the superior facet with respect to the transverse plane was also measured on computed tomography (CT) scans of 30 patients having neck injury without fracture/dislocation. The vertical and surface lengths of the superior facet were significantly lower (P < 0.01) at C6-C7 levels than at C3-5 levels. The anteroposterior diameter of the superior facet was smaller (P < 0.05) at C6 and C7 levels compared to C3-5 levels. Although the superior facet joint surface is in a more coronal orientation in lower cervical vertebrae, the inclination of the superior facet is more horizontal relative to the transverse plane when measured in vivo. A combination of lower height, smaller anteroposterior diameter of the superior facet, and a more horizontally oriented superior facet at C6 and C7 levels in vivo may explain the predilection of translation relative to one another in the lower cervical spine.

Robot-Assisted Laparoscopic Nephroureterectomy

Laparoscopic nephroureterectomy for upper-tract urothelial tumors is a minimally invasive approach that parallels the open technique in oncologic efficacy. Multiple approaches to manage the distal ureter have been described. We developed a new technique using the daVinci robot system to perform a transvesical excision of the distal ureter and bladder cuff. Ten consecutive patients with upper-tract urothelial cancer underwent a laparoscopic nephroureterectomy. The daVinci robot was docked through the umbilical, ipsilateral lateral rectus, and an additional contralateral lateral rectus port. The bladder was clam-shelled in a coronal orientation at the dome and the distal ureterectomy performed. Our technique was successful in all ten patients. The mean operative time for the entire case was 4.4 hours. The average hospital stay was 3 days. Robot-assisted laparoscopic nephroureterectomy is a safe, minimally invasive approach to upper- tract urothelial cancer that reduces the technical challenge of excision of the distal ureter.

Three‐dimensional dose verification for intensity modulated radiation therapy using optical CT based polymer gel dosimetry

Dose distributions generated from intensity-modulated-radiation-therapy (IMRT) treatment planning present high dose gradient regions in the boundaries between the target and the surrounding critical organs. Dose accuracy in these areas can be critical, and may affect the treatment. With the increasing use of IMRT in radiotherapy, there is an increased need for a dosimeter that allows for accurate determination of three-dimensional (3D) dose distributions with high spatial resolution. In this study, polymer gel dosimetry and an optical CT scanner have been employed to implement 3D dose verification for IMRT. A plastic cylinder of 17 cm diameter and 12 cm height, filled with BANG3 polymer gels (MGS Research, Inc., Madison, CT) and modified to optimal dose-response characteristics, was used for IMRT dose verification. The cylindrical gel phantom was immersed in a 24 x 24 x 20 cm water tank for an IMRT irradiation. The irradiated gel sample was then scanned with an optical CT scanner (MGS Research Inc., Madison, CT) utilizing a single He-Ne laser beam and a single photodiode detector. Similar to the x-ray CT process, filtered back-projection was used to reconstruct the 3D dose distribution. The dose distributions measured from the gel were compared with those from the IMRT treatment planning system. For comparative dosimetry, a solid water phantom of 24 x 24 x 20 cm, having the same geometry as the water tank for the gel phantom, was used for EDR2 film and ion chamber measurements. Root mean square (rms) deviations for both dose difference and distance-to-agreement (DTA) were used in three-dimensional analysis of the dose distribution comparison between treatment planning calculations and the gel measurement. Comparison of planar dose distributions among gel dosimeter, film, and the treatment planning system showed that the isodose lines were in good agreement on selected planes in axial, coronal, and sagittal orientations. Absolute point-dose verification was performed with ion chamber measurements at four different points, varying from 48% to 110% of the prescribed dose. The measured and calculated doses were found to agree to within 4.2% at all measurement points. For the comparison between the gel measurement and treatment planning calculations, rms deviations were 2%-6% for dose difference and 1-3 mm for DTA, at 60%-110% doses levels. The results from this study show that optical CT based polymer gel dosimetry has the potential to provide a high resolution, accurate, three-dimensional tool for IMRT dose distribution verification.

Safety and Efficacy of C2 Pedicle Screws Placed With Anatomic and Lateral C-Arm Guidance

This is a retrospective review of 150 C2 pedicle screw placements. Candidates had their C2 pedicle morphology assessed through three-dimensional imaging, including preoperative image guidance. After surgery, the patients were serially CT scanned. Follow-up, with fusion assessment, ranged from 1 to 12 years. We will show that an open technique combined with lateral C-arm guidance provides rapid placement of C2 pedicle screws. C2 pedicle screws can be successful anchors for a variety of cervical problems. Standard intraoperative image guidance, biplane fluoroscopy, or free hand techniques all have their drawbacks. After adequate C2 exposure, the C2 pedicle is palpated. The dissector remains stationary to provide coronal orientation while a lateral C-arm radiograph is obtained for sagittal orientation. The drill trajectory is set, the C2 pedicle cannulated, and a cancellous screw placed. A total of 71 patients had bilateral screws placed and 8 patients had unilateral screws placed. The overall complication rate was 2.7%. In our series, we have found a consistent way to cannulate the C2 pedicle. C2 fixation serves as an integral part of cervical reconstruction. Preoperative planning, anatomic knowledge, and lateral C-arm orientation create a low morbidity method for C2 screw placement.

BGEM: An In Situ Hybridization Database of Gene Expression in the Embryonic and Adult Mouse Nervous System

This article describes an open-access gene expression database analyzed for more than 2,000 genes on mouse nervous system tissue in the coronal, sagittal, and transverse orientation representing multiple developmental ages.

Trigeminusneuralgie: Wie häufig gibt es einen Gefäß-Nerven-Kontakt bei schmerzfreien Probanden?

To assess prospectively how often contacts are found between the trigeminal nerve and arteries or veins in the perimesencephalic cistern via MRI in normal volunteers. 48 volunteers without a history of trigeminal neuralgia were examined prospectively (MRI at 1.5 T; T2-CISS sequence, coronal orientation, 0.9 mm slice thickness). Two radiologists decided by consensus whether there was a nerve-vessel contact in the perimesencephalic cistern. In 27 % of the volunteers, no contact was found between the trigeminal nerve and regional vessels, while in 73 %, such a contact was present. In 61 % of the cases, the offending vessel was an artery, in 39 %, it was a vein. In 2 volunteers, a deformation of the nerve was noted. Contrary to what has been suggested by retrospective studies, the majority of normal volunteers, if studied prospectively, do show a contact between the trigeminal nerve and local vessels. A close proximity between the nerve and regional vessels is thus normal and is not necessarily proof of a pathological nerve-vessel conflict.

Is 3-dimensional volume sonography an effective alternative method to the standard 2-dimensional technique of measuring the nuchal translucency?

To determine whether 3-dimensional (3D) volume scanning is an effective alternative method of measuring nuchal translucency in first-trimester fetuses compared with the standard 2-dimensional (2D) technique, and to report a standardized method of evaluation. We measured the nuchal translucency of 29 fetuses between 11.4 and 13.9 weeks of age using the standard 2D sonographic technique with the fetus in a sagittal view. We then rescanned the fetus in a coronal orientation and obtained a 3D volume of the fetal neck area from crown to rump using a consistent technique. The sagittal orientation was reconstructed, and the width of the nuchal translucency was measured electronically using the reconstructed midsagittal view. The measurements using a conventional 2D sagittal view were then compared with the 3D reconstructed sagittal view. The nuchal translucency was adequately measured in all fetuses in which the 3D assessment was attempted. The nuchal translucencies of 29 consecutive fetuses were measured using both 2D and 3D multiplanar reconstruction of the fetal neck. The mean +/- standard deviation for the standard 2D assessment of the nuchal translucency was 1.7 +/- 1.4 mm. Using 3D reconstruction of the Z plane, the measurement was 1.8 +/- 1.6 mm. This was not a statistically significant difference (P = 0.4). There was a very high correlation between the two techniques (r = 0.984, P < 0.001). There is an excellent correlation between the measurements of the nuchal translucency using standard 2D scanning and those obtained from 3D multiplanar reconstruction of the Z plane. Using a consistent technique, the nuchal translucency can be accurately and reliably measured with a 3D rendering. This technique is potentially useful in fetuses that are not in an optimal position for standard 2D nuchal translucency measurement.

Repères échographiques de gyration cérébrale fœtale normale

Purpose Define normal sulcation patterns and their chronological order of appearance on transabdominal ultrasound by comparing them with brain maturation references available in fetopathological studies and MRI findings. Patients and methods By means of a prospective study, 158 normal fetal brains aged 21 to 34 gestational weeks have been analyzed with standardized data by transabdominal ultrasound in eleven different views using axial, coronal and sagittal orientation. Results . The sequential development of cerebral sulci has been described according to the gestational age. This chronology was consistent with anatomo-pathologic references presenting a mean late period of one week and with MRI but without any late period. This study is available on the following website: http://www.gyration-foetale.fr. Conclusion This ultrasound study provides accurate landmarks and imaging features of normal fetal brain sulcation. The analysis and the knowledge of this sulcation provide better understanding of the brain cortex maturation and may be helpful in diagnosing brain diseases.

Genetic Ablation of Polysialic Acid Causes Severe Neurodevelopmental Defects Rescued by Deletion of the Neural Cell Adhesion Molecule

Poly-alpha2,8-sialic acid (polySia) is a unique modification of the neural cell adhesion molecule, NCAM, tightly associated with neural development and plasticity. However, the vital role attributed to this carbohydrate polymer has been challenged by the mild phenotype of mice lacking polySia due to NCAM-deficiency. To dissect polySia and NCAM functions, we generated polySia-negative but NCAM-positive mice by simultaneous deletion of the two polysialyltransferase genes, St8sia-II and St8sia-IV. Beyond features shared with NCAM-null animals, a severe phenotype with specific brain wiring defects, progressive hydrocephalus, postnatal growth retardation, and precocious death was observed. These drastic defects were selectively rescued by additional deletion of NCAM, demonstrating that they originate from a gain of NCAM functions because of polySia deficiency. The data presented in this study reveal that the essential role of polySia resides in the control and coordination of NCAM interactions during mouse brain development. Moreover, this first demonstration in vivo that a highly specific glycan structure is more important than the glycoconjugate as a whole provides a novel view on the relevance of protein glycosylation for the complex process of building the vertebrate brain.

High Resolution MR Perfusion Imaging of the Kidneys at 3 Tesla without Administration of Contrast Media

The feasibility of high-resolution arterial spin labeling (ASL) perfusion imaging of the kidneys was tested and proven at 3 Tesla using a flow-sensitive alternating inversion recovery (FAIR) true fast imaging in steady precession (TrueFISP) technique. Kidney perfusion maps of six healthy volunteers and two patients were acquired using a clinical 3-Tesla whole-body scanner. An ASL sequence with FAIR spin preparation and a TrueFISP signal detection strategy was adapted for high-resolution perfusion imaging of the kidneys at 3 Tesla. To avoid banding artifacts in TrueFISP images, which are generally prominent at 3 Tesla, a frequency scout was implemented. Perfusion maps with an in-plane resolution of 1.5 mm were recorded in transverse and coronal orientation. For fast mapping of whole-kidney perfusion, an in-plane resolution of 2 mm was applied. In all volunteers and patients, high-resolution perfusion images with excellent image quality were able to be obtained in a measuring time of approximately 10 minutes. The whole kidney was able to be mapped with good image quality in less than 10 minutes. For all slices, a suitable frequency offset made it possible to reproduce the kidneys without TrueFISP artifacts. Perfusion values of the renal cortex ranged from 250 ml/100 g/min up to 400 ml/100 g/min (mean cortical perfusion right kidney 316 +/- 43, left 336 +/- 40). High-resolution ASL perfusion images of the whole kidney were able to be obtained with good image quality by means of a 3 Tesla MR setting within a clinically applicable measuring time, thus providing an alternative to conventional perfusion imaging involving potentially nephrotoxic contrast media.

MRI of Prostate Cancer at 1.5 and 3.0 T: Comparison of Image Quality in Tumor Detection and Staging

This prospective study was performed to compare the image quality, tumor delineation, and depiction of staging criteria on MRI of prostate cancer at 1.5 and 3.0 T. Twenty-four patients with prostate cancer underwent MRI at 1.5 T using the combined endorectal-body phased-array coil and at 3.0 T using the torso phased-array coil, among them 22 before undergoing radical prostatectomy. The prostate was imaged with T2-weighted sequences in axial and coronal orientations at both field strengths and, in addition, with an axial T1-weighted sequence at 1.5 T. Preoperative analysis of all MR images taken together was compared with the histologic findings to determine the accuracy of MRI for the local staging of prostate cancer. In a retroanalysis, the image quality, tumor delineation, and conspicuity of staging criteria were determined separately for both field strengths and compared. Statistical analysis was performed using Wilcoxon's and the McNemar tests. In the preoperative analysis, MRI (at both 1.5 and 3.0 T) had an accuracy of 73% for the local staging of prostate cancer. The retroanalysis yielded significantly better results for 1.5-T MRI with the endorectal-body phased-array coil in terms of image quality (p < 0.001) and tumor delineation (p = 0.012) than for 3.0-T MRI with the torso phased-array coil. Analysis of the individual staging criteria for extracapsular disease did not reveal a superiority of either of the two field strengths in the depiction of any of the criteria. Intraindividual comparison shows that image quality and delineation of prostate cancer at 1.5 T with the use of an endorectal coil in a pelvic phased-array is superior to the higher field strength of 3.0 T with a torso phased-array coil alone. As long as no endorectal coil is available for 3-T imaging, imaging at 1.5 T using the combined endorectal-body phased-array coil will continue to be the gold standard for prostate imaging.

Ist der einseitige Strabismus sursoadductorius eine paretische Störung? - Kernspintomographische Untersuchungen

Recent reports postulate that the concomitant vertical deviation found in congenital superior oblique palsy is due to mechanical abnormalities rather than a congenitally paretic muscle, and is overcome in most patients by fusion. On the basis of the clinical characteristics alone a primary paresis is indeed unlikely. Although intraoperatively a different elasticity of the superior oblique tendon exists in congenital versus acquired cases of superior oblique palsy, preoperatively performed MR imaging shows that the clinical findings in congenital superior oblique muscle malfunction could nevertheless be of paretic origin. Seventeen consecutive patients (males: n = 13; females: n = 4) were examined. The vertical deviation in adduction was concomitant in vertical versions, the excyclotropia was small and concomitant in all directions of gaze and was less than 10 degrees even after diagnostic occlusion. All patients showed a positive Bielschowsky head tilt phenomenon and large fusional ability. We performed preoperative MR imaging of both orbits in high resolution 3 mm sections in coronal and axial orientations with and without contrast enhancement. In sixteen patients we found a significant reduction in muscle volume or even total aplasia of the superior oblique muscle of the affected side in comparison to the sound muscle on the other side. In contrast, two patients had a full blown clinical picture of a congenital superior oblique palsy but showed symmetrical muscle volumes on both sides in all coronal sections. Hypoplasia or aplasia of the superior oblique muscle on magnetic resonance imaging provides evidence for a primary paretic cause for the vertical squint found with congenital superior oblique dysfunction. It is not clear, however, whether this is caused by a primary hypoplasia or is of neurogenic origin. Our data together with the consistent difference in tendon morphology of the congenital and acquired forms of superior oblique palsy seem to exclude a purely neurogenic cause for the affection.

Visuelle Abschätzung der funktionellen Lungenanteile in der HRCT und 3He-MRT bei Patienten nach Einzel-Lungentransplantation: Vergleich mit der absoluten Volumetrie

Visual assessment of the ventilation using HRCT and (3)He-MRI in patients after single lung transplantation (SLTX). Analysis of specific ventilation defects found with (3)He-MRI and morphological changes found with HRCT. We evaluated 8male patients (54 +/- 6 years) suffering from emphysema and six patients (3males and 3 females, 58 +/- 9.5 years) suffering from idiopathic pulmonary fibrosis (IPF) after SLTX. The morphological changes at HRCT were classified and localized. In (3)He-MRI (2D FLASH), 10 to 14 slices (slice thickness 10 mm, gap 5 mm) were acquired in coronal orientation to cover the whole lung. Ventilation defects were localized and characterized. The visually estimated ventilation was recorded on a 5-point scoring system. A double threshold technique was applied to volumetric quantification in (3)He-MRI to serve as internal reference. We found no correlation between morphological changes in HRCT and ventilation defects in (3)He-MRI. The visual assessment of ventilation in (3)He-MRI was sufficient in patients with emphysema, but this was not confirmed in patients with IPF. The visual assessment in HRCT did not correlate with the volumetric evaluation in both conditions. The various ventilation defects were not linked to specific morphological changes. For the visually assessed ventilation in patients with emphysema, (3)He-MRI is superior to HRCT.

Characterization of dentin, enamel, and carious lesions by a polarization-sensitive optical coherence tomography system

Enamel and dentin are the primary components of human teeth. Both of them have a strong polarization effect. We designed a polarization-sensitive optical coherence tomography (PSOCT) system to study the spatially resolved scattering and polarization phenomena of teeth. The system is constructed in free space to avoid the complexity of polarization control in fiber-based PSOCT. The structural features of enamel were evaluated in five human teeth that had no visible evidence of caries. The teeth were subsequently sectioned in mesial distal orientation and coronal orientation. Then the structural aspects of dentin were evaluated. OCT images were made of the mantel dentin near the dentin-enamel junction. Five teeth with interproximal and occlusal caries were also studied. With two channel and phase-retardation images, PSOCT provided better functional contrast and more detailed structural information than conventional OCT. For a better description of the measured PSOCT data, we classify these features by two types, i.e., the local textural features and the global structural features. This study indicates that PSOCT has the potential to be a powerful tool for research of dental formation and caries diagnosis.

Multislice computed tomography perfusion imaging for visualization of acute pulmonary embolism: animal experience

The purpose of our animal study was to evaluate a new computed tomography (CT) subtraction technique for visualization of perfusion defects within the lung parenchyma in subsegmental pulmonary embolism (PE). Seven healthy pigs were entered into a prospective trial. Acute PE was artificially induced by fresh clot material prior to the CT scans. Within a single breath-hold, whole thorax CT scans were performed with a 16-slice multidetector-row CT scanner (SOMATOM Sensation 16; Siemens, Forchheim, Germany) before and after intravenous application of 80 ml of contrast medium with a flow rate of 4 ml/s, followed by a saline chaser. The scan parameters were 120 kV and 100 mAs(eff), using a thin collimation of 16x0.75 mm and a table speed/rotation of 15-18 mm (pitch, 1.25-1.5; rotation time, 0.5 s). Axial source images were reconstructed with an effective slice thickness of 1 mm (overlap, 30%). A new automatic subtraction technique was used. After 3D segmentation of the lungs in the plain and contrast-enhanced series, threshold-based extraction of major airways and vascular structures in the contrast images was performed. This segmentation was repeated in the plain CT images segmenting the same number of vessels and airways as in the contrast images. Both scans were registered onto each other using nonrigid registration. After registration both image sets were filtered in a nonlinear fashion excluding segmented airways and vessels. After subtracting the plain CT data from the contrast data the resulting enhancement images were color-encoded and overlaid onto the contrast-enhanced CT angiography (CTA) images. This color-encoded combined display of parenchymal enhancement of the lungs was evaluated interactively on a workstation (Leonardo, Siemens) in axial, coronal and sagittal plane orientations. Axial contrast-enhanced CTA images were rated first, followed by an analysis of the combination images. Finally, CTA images were reread focusing on areas with perfusion deficits indicating PE on the color-coded enhancement display. Subtraction was feasible for all seven studies. In one animal, opacification of the pulmonary arteries was suboptimal owing to heart insufficiency. In the remaining six pigs, a total of 37 perfusion defects were clearly assessable downstream of occluded subsegmental arteries, showing lower or missing enhancement compared with normally perfused lung parenchyma. Indeterminate findings from CTA showed typical PE perfusion defects in four out of six cases on CT subtraction. Additionally, 22 peripheral triangular-shaped enhancement defects were delineated. Nine of these findings were reclassified as definitely being caused by PE on second reading of the CTA data sets. Our initial results have shown that this new subtraction technique for perfusion imaging of PE is feasible, using routine contrast delivery. Dedicated examination protocols are mandatory for adequate opacification of the pulmonary arteries and for optimization of data sets for subsequent subtraction. Perfusion imaging allows a comprehensive assessment of morphology and function, providing more accurate information on acute PE.

Multiplanar transcranial ultrasound imaging: Standards, landmarks and correlation with magnetic resonance imaging

The purpose of this study was to define a standardized multiplanar approach for transcranial ultrasound (US) imaging of brain parenchyma based on matched data from 3-D US and 3-D magnetic resonance imaging (MRI). The potential and limitations of multiple insonation planes in transverse and coronal orientation were evaluated for the visualization of intracranial landmarks in 60 healthy individuals (18 to 83 years old, mean 41.4 years) with sufficient temporal bone windows. Landmarks regularly visualized even in moderate sonographic conditions with identification rates of > 75% were mesencephalon, pons, third ventricle, lateral ventricles, falx, thalamus, basal ganglia, pineal gland and temporal lobe. Identification of medulla oblongata, fourth ventricle, cerebellar structures, hippocampus, insula, frontal, parietal and occipital lobes was more difficult (< 75%). We hypothesize that multiplanar transcranial US images, with standardized specification of tilt angles and orientation, not only allow comparison with other neuroimaging modalities, but may also provide a more objective framework for US monitoring of cerebral disease than freehand scanning.

Dosisoptimierung der Mehrzeilen-Spiral-CT (MSCT) des Mittelgesichts

To optimize multislice computed tomography (MSCT) protocols of the midface for dose reduction and adequate image quality. MSCT (Somatom Volume Zoom, Siemens) of the midface was performed on 3 cadavers within 24 hours of death with successive reduction of the tube current, applying 150, 100, 70 and 30 mAs at 120 kV as well as 40 and 21 mAs at 80 kV. At 120 kV, a pitch of 0.875 and collimation of 4x1 mm were used, and at 80 kV, a pitch of 0.7 and collimation of 2x0.5 mm. Images were reconstructed in transverse and coronal orientation. Qualitative image analysis was separately performed by two radiologists using a five-point scale (1 = excellent; 5 = poor) applying the following parameters: image quality, demarcation and sharpness of lamellar bone, overall image quality, and image noise (1 = minor; 5 = strong). The effective body dose [mSv] and organ dose [mSv] of the ocular lens (using the dosimetry system "WINdose") were calculated, and the interobserver agreement (kappa coefficient) was determined. For the evaluation of the lamellar bone, adequate sharpness, demarcation and image quality was demonstrated at 120 kV/30 mAs, and for the overall image quality and noise, 120 kV/40 mAs was acceptable. With regard to image quality, the effective body dose could be reduced from 1.89 mSv to 0.34 mSv and the organ dose of the ocular lens from 27.2 mSv to 4.8 mSv. Interobserver agreement was moderate (kappa = 0.39). Adequate image quality was achieved for MSCT protocols of the midface with 30 mAs at 120 kV, resulting in a dose reduction of 70 % in comparison to standard protocols.

Proximal Crescentic Metatarsal Osteotomy: The Effect of Saw Blade Orientation on First Ray Elevation

Moderate and severe hallux valgus deformities generally require a proximal metatarsal osteotomy to correct a widened intermetatarsal angle. Although excellent results have been reported using the proximal crescentic osteotomy, concerns have been raised about the incidence of postoperative dorsal malunion, which may lead to transfer lesions. The objectives of this paper were to evaluate the influence of saw blade angulation on the final position of the first metatarsal and to test a new technique used to ensure proper orientation of the osteotomy. For part I of the study, 26 Sawbones specimens with hallux valgus deformities were corrected using a proximal crescentic osteotomy with the saw blade position incrementally rotated in the coronal plane. The sagittal change in the final position of the metatarsal was quantified radiographically and correlated to the saw blade orientation. For part II of the study, a Kirschner wire was placed in a vertical position into the medial cuneiform to serve as a guide for the crescentic saw blade in 13 cadaver feet with hallux valgus. Metatarsus primus elevatus was measured after surgical correction. Part I of the study demonstrated a highly linear relationship (R2=0.95) between first metatarsal elevation and the orientation of the saw blade. Every 10-degree of saw blade angulation resulted in a 2-mm change in the sagittal position of the first metatarsal. In part II of the study, the average change in metatarsus primus elevation for the 13 specimens after surgical correction of the hallux valgus deformity was only 1.1 mm (range -3.9 to +4.9 mm). Eleven of the 13 specimens had less than 2.5 mm of elevatus. Dorsal malunion of the first metatarsal after proximal crescentic osteotomy is a recognized complication. The final position of the hallux metatarsal is influenced by the coronal plane orientation of the saw. A new technique is described to aid the surgeon in proper alignment of the saw and help prevent excessive first ray elevation.