Oblique Coronal Plane Research Articles

Effectiveness of Ultrasound-Guided Corticosteroid Injection for the Treatment of Gluteus Medius Tendinopathy

The objective of our study was to evaluate the effectiveness of ultrasound-guided corticosteroid injection for the treatment of gluteus medius tendinopathy. We prospectively evaluated 54 consecutive patients (48 women, six men; mean age, 54.7 years; mean body mass index, 26 kg/m2) with a clinical diagnosis of gluteus medius tendinopathy. Pain assessment using a 10-cm visual analog scale (VAS) was obtained as part of the initial clinical evaluation of all patients. A hip ultrasound study was performed followed by a gluteus medius peritendinous ultrasound-guided injection of 30 mg of triamcinolone combined with 3 mL of bupivacaine 0.5% using an anterior oblique coronal plane. One month after treatment, participants were reassessed clinically, and they were asked to quantify their pain using the VAS pain score and their satisfaction with the outcome of the injection using a 4-point rating scale (very satisfied, somewhat satisfied, somewhat dissatisfied, or very dissatisfied). Statistical analysis included a paired Student's t test (comparison of pain levels before and after treatment, p=0.05) and a multivariate analysis of covariance. There was a 55% average reduction of pain level before versus after treatment (mean VAS pain score, 6.4 vs 2.9 cm, respectively; p<0.001). One month after treatment, 72% of the patients showed a clinically significant improvement in pain level, which was defined as a reduction in the VAS pain score of >or=30%. Seventy percent of patients were satisfied with the results of the intervention. No correlation was shown between treatment outcome and any of the clinical variables or ultrasound findings. Our study shows that a peritendinous ultrasound-guided corticosteroid injection may be an effective treatment of gluteus medius tendinopathy.

Accessory left atrial diverticulae: contractile properties depicted with 64-slice cine-cardiac CT

To assess the contractility of accessory left atrial appendages (LAAs) using multiphasic cardiac CT. We retrospectively analyzed the presence, location, size and contractile properties of accessory LAAs using multiphasic cardiac 64-slice CT in 102 consecutive patients (63 males, 39 females, mean age 57). Multiplanar reformats were used to create image planes in axial oblique, sagittal oblique and coronal oblique planes. For all appendages with an orifice diameter >or= 10 mm, axial and sagittal diameters and appendage volumes were recorded in atrial diastole and systole. Regression analysis was performed to assess which imaging appearances best predicted accessory appendage contractility. Twenty-three (23%) patients demonstrated an accessory LAA, all identified along the anterior LA wall. Dimensions for axial oblique (AOD) and sagittal oblique (SOD) diameters and sagittal oblique length (SOL) were 6.3-19, 3.4-20 and 5-21 mm, respectively. All appendages (>or=10 mm) demonstrated significant contraction during atrial systole (greatest diameter reduction was AOD [3.8 mm, 27%]). Significant correlations were noted between AOD-contraction and AOD (R = 0.57, P < 0.05) and SOD-contraction and AOD, SOD and SOL (R = 0.6, P < 0.05). Mean diverticulum volume in atrial diastole was 468.4 +/- 493 mm(3) and in systole was 171.2 +/- 122 mm(3), indicating a mean change in volume of 297.2 +/- 390 mm(3), P < 0.0001. Stepwise multiple regression analysis revealed SOL to be the strongest independent predictor of appendage contractility (R(2) = 0.86, P < 0.0001) followed by SOD (R(2) = 0.91, P < 0.0001). Accessory LAAs show significant contractile properties on cardiac CT. Those accessory LAAs with a large sagittal height or depth should be evaluated for contractile properties, and if present should be examined for ectopic activity during electrophysiological studies.

Tunnel Enlargement after Double-Bundle Anterior Cruciate Ligament Reconstruction (SS-43)

Sixty patients were randomized with closed envelopes into either double-bundle or single-bundle anterior cruciate ligament reconstruction with hamstring tendons and bioabsorbable screw fixation. After 2-year follow-up, tunnel enlargement was determined by MRI measuring the widths perpendicular to the long axis of the tunnels on an oblique coronal and sagittal plane. Double-bundle ACL reconstruction technique results in less tunnel enlargement in each tunnel on tibial side than the single-bundle technique with similar fixation methods, graft material, and rehabilitation.

Left Ventricular Apical Thinning as Normal Anatomy

Apical thinning of the left ventricular myocardium has been described by anatomists as a normal feature. Nonetheless, it does not appear in most anatomic atlases. We investigated its presence in healthy patients and patients with left ventricular hypertrophy using coronary computed tomographic arteriography (CCTA). Sixty-four patients without a history of cardiac disease and 8 patients with left ventricular hypertrophy were imaged using coronary computed tomographic arteriography. All 64 patients had a focus of myocardial thinning at the left ventricular apex (mean, 1.2 mm [SD, 1.1 mm]). Its average span in the oblique coronal plane was 4.4 mm (2.9 mm), corresponding to a median area of 14.3 mm2 with an interquartile range of 3.9 to 31.6. The focus faced 4.8 degrees (5.9 degrees) toward the diaphragmatic side of the apex. The 8 hypertrophied hearts also had a zone of apical thinning. In a subset of 12 patients in whom functional data were analyzed, this focus did not thicken or move over the cardiac cycle. A zone of substantial thinning of the left ventricular apex is a normal anatomic feature.

Partial Loss of Hippocampal Striation in Medial Temporal Lobe Epilepsy: Pilot Evaluation with High-Spatial-Resolution T2-weighted MR Imaging at 3.0 T

To determine whether partial loss of the hippocampal striation (PLHS) at 3.0 T is more accurate than the currently accepted methods of using conventional magnetic resonance (MR) imaging to detect hippocampal sclerosis in medial temporal lobe epilepsy (MTLE). This retrospective study had institutional review board approval, and informed consent was waived. Fluid-attenuated inversion-recovery (FLAIR) MR images and T2-weighted MR images in the oblique coronal plane in 22 consecutive patients (10 men, 12 female patients; mean age, 41.0 years; range, 14-76 years) (25 hemispheres) with a clinical diagnosis of MTLE were retrospectively evaluated. Twenty-five hippocampi in 15 subjects without epilepsy were evaluated as age-matched controls. The volumes and thicknesses of the four anatomic sections of the hippocampi were quantitatively measured on the T2-weighted images. Two radiologists independently reviewed the MR imaging findings of the hippocampus regarding atrophy, abnormal signal intensity, and PLHS on each side separately, without comparing both sides. Sensitivity and specificity were calculated among the MR imaging findings. Signal intensity abnormality on FLAIR images had a sensitivity of 36%, a specificity of 96%, and an accuracy of 66% for the diagnosis of hippocampal sclerosis. PLHS on T2-weighted MR images had a sensitivity of 76% and a specificity of 80% for the diagnosis of hippocampal sclerosis. The sensitivity for PLHS was higher than that for atrophy (44%) and abnormal signal intensity (48%) of the hippocampus on T2-weighted MR images. Although the mean volume of the hippocampus and the thickness of the hippocampal body were significantly smaller for patients with MTLE than for control subjects (P < .001 for both), there was no clear distinguishing threshold value between abnormal and normal hippocampi. PLHS showed the highest sensitivity for MTLE. This MR imaging feature might improve the accuracy of the diagnosis of bilateral hippocampal sclerosis, although further research is required.

Magnetic resonance imaging of the ocular motor nerves in normal volunteers

To display the detail functional anatomy of ocular motor nerves in the orbits, cavernous sinus and brainstem by high-resolution MRI. Twenty normal subjects between 24 and 38 years of age, mean age was 28.25 +/- 4.07 (SD). Imaging of the ocular motor nerves at the brainstem was performed in 0.8 mm thickness image planes using 3D-FIESTA sequence; nerves in the cavernous sinus was imaged with a head coil, the FSE/T(1)WI was obtained in coronal planes; nerves to extraocular muscles (EOMs) in the orbits were imaged with FSE/T(1)WI oblique-coronal planes using surface coils, and within 2.0 mm thick planes. A human orbit was celloidin embedding and serially sectioned at 0.1 mm of thickness for HE stain, which would be used to distinguish motor nerves to the EOMs. Oculomotor nerves (CN3) and abducens (CN6) of the cisternal segment were well demonstrable in all normal subjects. Trochlear nerves (CN4) were depicted 95%. CN3 could be demonstrated consistently in the cavernous sinus, because of their small diameter, CN4 and CN6 not always detectable. The larger inferior division of CN3 and branches to the target EOMs and CN6 were demonstrated well in all species. The superior division of CN3 was demonstrated 60%, CN4 was showed 40%. 3D-FIESTA Sequence combined with MPR (Multiplanar Reformation) could precisely show the ocular motor nerves, as well as the relationships with adjacent structures in the cistern. The inferior division of CN3 and the CN6 could be well depicted in the orbits. But of the small sizes and complicated neighboring structures in the orbit, the superior division of the CN3 and the CN4 could not be demonstrated consistently. The capabilities of MRI can be fully used only with thorough knowledge of the complicated topographic relationships in the corresponding region.

Surgical anatomy of hepatic caudate lobe based on 3D virtual human liver

Objective To provide practical anatomy of hepatic eaudate lobe for clinical practice. Method Based on Chinese Visible Human 1--5 and assisted by technique of 3D visualization, the dig-itized 3D models of liver were reconstructed and the anatomy of caudate lobe was investigated. Results The right and ventral boundaries of caudate lobe were obscure. The coronal oblique plane through the confluence of hepatic veins and the fissura ligamenti venosi and the sagittal oblique plane through the end of right hepatic vein and the gallbladder fossa could stand for the relative ventral and right borders of the caudate lobe. The caudate lobe could be divided into 2 principal regions: the Spiegel lobe and the paraeaval portion. Conclusion Our classification and the relative borders of the caudate lobe might be reasonable and practical. The 3D visualization is a convenient and accurate study method on clinical a-natomy. Key words: Anatomy; Caudate lobe; 3D visualization; Chinese Visible Human

Tunnel Enlargement After Double-Bundle Anterior Cruciate Ligament Reconstruction: A Prospective, Randomized Study

The aim of this study was to compare tunnel enlargement in patients with double-bundle and single-bundle anterior cruciate ligament (ACL) reconstruction. Sixty patients were randomized by closed envelopes into 2 different groups of ACL reconstruction with hamstring tendons: double-bundle technique with bioabsorbable screw fixation (n = 35) and single-bundle technique with bioabsorbable screw fixation (n = 25). Magnetic resonance imaging evaluation was performed in 53 patients (88%) (32 in double-bundle group and 21 in single-bundle group) for a mean of 27 months' follow-up (range, 24 to 36 months). Tunnel enlargement was determined by digital measurement of the widths perpendicular to the long axis of the tunnels on an oblique coronal and sagittal plane. The magnetic resonance imaging measurements were compared with the intraoperative drill diameter. No significant differences were found between the double-bundle group and the single-bundle group in tunnel enlargement on the femoral side. However, on the tibial side, tunnel enlargement was greater in the single-bundle group than in the double-bundle group in each tunnel (P = .051). In all knees, tunnel enlargement both on the tibial side and on the femoral side correlated significantly with the anterior and rotational laxity of the operated knee. In the double-bundle group, no tunnel communication between the anteromedial and posterolateral tunnels was seen in any of the patients on either the tibial side or femoral side. This prospective, randomized study showed that our double-bundle ACL reconstruction technique results in less tunnel enlargement in each tunnel on the tibial side than the single-bundle technique with similar fixation methods, graft material, and rehabilitation. In addition, no tunnel communication was observed in the patients undergoing double-bundle ACL reconstruction. The clinical results were good in both groups. However, the patients who had more tunnel enlargement had significantly more anterior and rotational laxity of the operated knee as well. Level I, therapeutic randomized controlled trial.

MR Imaging Appearances of Acromioclavicular Joint Dislocation

The key structures involved in dislocation of the acromioclavicular joint (ACJ) are the joint itself and the strong accessory coracoclavicular ligament. ACJ dislocations are classified with the Rockwood system, which comprises six grades of injury. Treatment planning requires accurate grading of the ACJ disruption, but correct classification can be difficult with clinical assessment. Magnetic resonance (MR) imaging has a well-established role in evaluation of ACJ pain. MR imaging performed in the coronal oblique plane parallel to the distal clavicle allows assessment of the acromioclavicular and coracoclavicular ligaments owing to its in-plane orientation in relation to these structures. This technique enables distinction between grade 2 and grade 3 injuries, which can be difficult with conventional clinical and radiographic evaluation. In addition, diagnosis of grade 1 injuries is possible by demonstration of a ruptured superiodorsal acromioclavicular ligament. Resultant thickening of the acromioclavicular or coracoclavicular ligament allows identification of chronic ACJ injuries.

Effect of compaction drilling during ACL reconstruction with hamstrings on postoperative tunnel widening

This study investigates whether the amount of tibial and femoral bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction with hamstrings can be reduced by compaction bone tunnel drilling. Patients undergoing primary ACL reconstruction with four-strand hamstrings (n = 26) were matched to either extraction drilling (n = 13) or compaction drilling (n = 13). Extracortical femoral fixation was by means of a 20 mm Endobutton CL and tibial fixation was by resorbable interference screw. A CT scan was performed on the second postoperative day and an average of 4 months (range 3.8-5 months) postoperatively in all patients. Tunnel enlargement was determined by digitally measuring the widths perpendicular to the long axis of the tunnels on an oblique coronal and axial plane. The CT measurements were compared to the intraoperative drill diameter. With extraction drilling the average tibial tunnel diameter proximal to the interference screw increased from 8.5 to 10.4 mm (P < 0.0001) and the average femoral tunnel from 8.0 to 10.6 mm (P < 0.0001). With compaction drilling it increased from 8.2 to 10.0 mm (P < 0.0001) and from 7.6 to 9.7 mm (P < 0.002), respectively. Tunnel widening was 22% on the tibial side for both groups and 33 versus 28% on the femoral side (P = 0.09) for extraction versus compaction drilling. There was a significant tibial and femoral tunnel widening on CT an average of only 4 months following ACL reconstruction with hamstrings. Compaction drilling with a stepped router did not prove to reduce the postoperative tunnel widening significantly. Tunnel widening was higher on the femoral side which could be related to the extracortical femoral fixation technique. Level 4.

Oblique MR imaging of the anterior cruciate ligament based on three‐dimensional orientation

To investigate the three-dimensional (3D) course of the anterior cruciate ligament (ACL) and determine the optimum planes for oblique full-length MRI of the ligament. Twenty-five healthy volunteers were examined. Axial proton density-weighted (PDw) images of the knees of 20 volunteers were obtained. 3D paths along the course of the ACL and corresponding tangents were constructed. Angles between these tangents and reference lines RFL-1 (the line connecting the posterior edges of the femoral condyles), RFL-2 (the line through the intercondylar joint space), and RFL-3 (the line connecting the anterior and posterior edge of the medial tibial condyle) were measured. These angles were used for oblique T2-weighted (T2w) MRI of the knees of the remaining five volunteers, and the number of slices that depicted the entire ACL was calculated. The mean angles to the ACL were 74.0 degrees for RFL-1, 79.9 degrees for RFL-2, and 70.4 degrees for RFL-3. Full-length visualization of the ACL was demonstrated by 1.4 slices using the sagittal oblique plane prescribed for RFL-1, 2.4 slices using the sagittal oblique plane prescribed for RFL-2, and 1.4 slices using the coronal oblique plane prescribed for RFL-3. The ACL is best depicted using a sagittal oblique imaging plane angled at 80 degrees from a line through the intercondylar joint space.

Can isotropic fast gradient echo imaging be substituted for conventional T1 weighted sequences in shoulder MR arthrography at 3 Tesla?

To assess the practical utility of isotropic shoulder imaging in patients undergoing MR arthrography. Isotropic shoulder imaging can be performed in less than three minutes with use of fast gradients. Two experienced musculoskeletal radiologists retrospectively interpreted MR images of the shoulder in 100 consecutive patients undergoing MR arthrography of the shoulder. All patients underwent MRI of the shoulder in oblique coronal, oblique sagittal, and axial planes on a 3.0-Tesla MRI system. All patients had conventional fast spin-echo T1-weighted imaging. All patients also had thin section (0.4 mm) isotropic spoiled gradient echo images performed. A total of 67 of the 100 patients underwent subsequent arthroscopy and results were compared with MR interpretations. There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears (seven articular surface and two bursal surface), 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated by consensus retrospective reading of the 100 shoulder MR exams. There was no difference in interpretation of the isotropic images as compared to the conventionally acquired images in the oblique coronal, oblique sagittal, and axial planes. Some patients had more than one finding on each exam. A total of 67 patients went on to arthroscopy. There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears, 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated on arthroscopy. All full- and partial-thickness supraspinatus tendon tears seen at arthroscopy were seen on consensus MR reading. A total of 19 out of the 21 patients with superior labral anterior posterior (SLAP) tears at arthroscopy were seen on consensus MR reading. A total of 16 of the 18 anterior labral tears and six of the seven posterior labral tears seen at arthroscopy were seen on consensus MR reading. Some of the 67 patients had more than one finding on arthroscopy. Isotropic imaging of the shoulder is practical in clinical imaging when performed with use of fast gradients on a 3-Tesla system. Isotropic imaging provides the same clinical information as conventional imaging and can be acquired in less than three minutes.

T2mapping of hip articular cartilage in healthy volunteers at 3T: A study of topographic variation

To perform baseline T2 mapping of the hips of healthy volunteers, focusing on topographic variation, because no detailed study has involved hips. T2 mapping is a quantitative magnetic resonance imaging (MRI) technique that evaluates cartilage matrix components. Hips of 12 healthy adults (six men and six women; mean age = 29.5 +/- 4.9 years) were studied with a 3.0-Tesla MRI system. T2 measurement in the oblique-coronal plane used a multi-spin-echo (MSE) sequence. Femoral cartilage was divided into 12 radial sections; acetabular cartilage was divided into six radial sections, and each section was divided into two layers representing the superficial and deep halves of the cartilage. T2 of these sections and layers were measured. Femoral cartilage T2 was the shortest (-20 degrees to 20 degrees and -10 degrees to 10 degrees, superficial and deep layers), with an increase near the magic angle (54.7 degrees ). Acetabular cartilage T2 in both layers was shorter in the periphery than the other parts, especially at 20 degrees to 30 degrees. There were no significant differences in T2 between right and left hips or between men and women. Topographic variation exists in hip cartilage T2 in young, healthy adults. These findings should be taken into account when T2 mapping is applied to patients with degenerative cartilage.

3-T MR imaging of partial ACL tears: a cadaver study

Magnetic resonance imaging (MRI) is the most commonly used diagnostic imaging procedure for suspected injuries to the anterior cruciate ligament (ACL). However, MRI has less utility for the evaluation of partial ACL tears. The goal of this study was to evaluate the possibility of distinguishing partial ACL tears applying the double bundle concept by dividing the ACL anatomy in the anteromedial (AM) and posterolateral bundle (PL). Six human cadaver knees were used in this laboratory study. The protocol consisted of sagittal, oblique coronal, and oblique sagittal proton-density-weighted fast spin echo sequences. After MRI the AM and the PL bundle were severed to mimic different partial ACL rupture patterns. MRI scanning of each knee was repeated, to record the quantitative parameters tilt and ACL angles and discontinuity as a nonquantitative parameter. Three orthopaedic surgeons and two radiologists were enlisted as blinded observers to evaluate the images. The transection patterns could be differentiated by evaluating discontinuity both in the paracoronal and in the sagittal plane. Evaluating the transection patterns, the AM bundle reached a better result in both planes compared to the PL bundle and the paracoronal plane had a better result in assessing the transection patterns compared to the sagittal plane for the PL bundle. Partial ACL transections could predictably be recognized on oblique sagittal and oblique coronal planes utilizing 3-T MRI technology. This concept allows a more precise description of ACL rupture patterns and might lead to a more distinctive approach for reconstructive surgery. The presurgical planning could be improved by applying a treatment algorithm based on a description of each bundle as intact or ruptured, leading to a reconstruction of the torn and a preservation of the intact bundle.

Imaging processing for CT angiography of the cervicocranial arteries: evaluation of reformatting technique

The aim of this study was to compare computed tomography angiography (CTA) sliding-thin-slab (STS) multiplanar reformatting (MPR), STS maximum intensity projection (MIP) and three-dimensional (3D) volume rendering (VR) reformatting techniques in the evaluation of cervicocranial arteries. Twenty patients examined with multislice CT were included in this study. CTA images were reformatted as STS-MIP, STS-MPR and 3DVR in orthogonal planes and in the oblique-coronal plane. Images were evaluated in consensus by two radiologists, with a third radiologist to resolve discordances in grading image quality parameters. The Spearman correlation analysis was performed to compare results and to obtain the correlation between scores resulting from the evaluation of parameters considered with the different techniques used (STSMIP, STS-MPR and 3DVR). STS-MIP images were significantly superior to STSMPR images for all parameters considered (p<0.05). Obliquecoronal 3DVR images were significantly superior to obliquecoronal STS-MIP images in the evaluation of vertebrobasilar vessels (p<0.05); in all other cases, 3DVR images were equivalent to STS-MIP images. STS-MIP images should be the primary reformatting technique for CTA of the cervicocranial arteries in addition to viewing the source images; 3DVR images can play an important role after a previsional diagnosis is made on the STS-MIP images.

Observations on Bone Tunnel Enlargement After Double-Bundle Anterior Cruciate Ligament Reconstruction

The purpose of this study was to determine the amount of tibial and femoral bone tunnel enlargement after double-bundle anterior cruciate ligament (ACL) reconstruction. Twenty-five consecutive patients undergoing primary double-bundle hamstring ACL reconstruction were included in a prospective case series. Femoral fixation was performed by means of 2 EndoButton CL devices (Smith & Nephew Endoscopy, Andover, MA), and tibial fixation was done with 2 bioresorbable interference screws. Magnetic resonance imaging (MRI) was performed in all patients at a mean of 12.3 months postoperatively. Tunnel enlargement was determined by digitally measuring the widths perpendicular to the long axis of the anteromedial (AM) and posterolateral (PL) tunnels on an oblique coronal and axial plane. The MRI measurements were compared with the intraoperative drill diameter. The mean tibial AM bone tunnel diameter increased from 0.74 to 1.06 cm, and the mean PL diameter increased from 0.60 to 0.89 cm. The mean femoral AM bone tunnel diameter increased from 0.71 to 0.97 cm, and the mean PL diameter increased from 0.58 to 0.85 cm. Bone tunnel enlargement was 43% (P = .001) for both tibial tunnels and 35% (P = .001) versus 48% (P < .001) for the femoral AM bone tunnel versus the PL femoral bone tunnel. On the tibial side, communication of the bone tunnels occurred in 41% of patients. This study shows significant tibial and femoral bone tunnel enlargement on MRI after 4-tunnel double-bundle ACL reconstruction 1 year postoperatively. In 41% of patients separate tibial bone tunnel measurements were impossible because of tunnel communication caused by intraoperative bone tunnel drilling, screw contact, or postoperative bone tunnel enlargement. On the femoral side, no bone tunnel communication occurred. The short-term clinical results were good and were not influenced by tunnel communication. Level IV, therapeutic case series.

Visualization of motor nerves to the extraocular muscles by magnetic resonance imaging

Purpose: Magnetic resonance imaging now enables visualization of the motor nerves to the extraocular muscles (EOMs) in the deep orbit. We use serial section of a normal human orbit as reference to identify the nerves. Methods: A human orbit was celloidin embedding and serially sectioned at 0.1 μm thickness by HE stain to distinguish motor nerves to the EOMs. Nerves were imaged with FSE T1WI in orbits of 10 normal volunteers in oblique-coronal planes within 2.0 mm thickness by surface coils. Results: At the level of posterior ethmoidal canal with center gaze of subjects, branches of motor nerves appeared in close contact to the corresponding EOMs. Adjacent to the superior ophthalmic vein and ophthalmic artery, the superior division of oculomotor nerve could not be traced consistently, as shown in 13 orbits (61%); inferior division of CN3 and branches to the target EOMs were demonstrated well in all subjects. The abducens (CN6) were demonstrated consistently, while trochlear nerves (CN4), coursing along the periosteum of paries superior orbitae and levator palpebrae superioris, were hard to be visualized, as shown in eight orbits (40%). Conclusion: The inferior division of CN3 and CN6 can readily be visualized in the orbit. But of the small sizes and complicated neighboring structures in the orbit, the superior division of the CN3 and CN4 could not be demonstrated consistently.

Scalar Localization of the Electrode Array After Cochlear Implantation

Improved resolution available with 64-slice multidetector computed tomography (MDCT) could potentially be used clinically to localize the cochlear implant (CI) electrode array within the basal turn. In CI surgery, the electrode array should be inserted into and remain within the scala tympani to avoid injury to Reissner's membrane and the scala media. Correlating the position of the electrode in the basal turn with surgical technique and implant design could be helpful in improving outcomes. After a standard left mastoid exposure of the round window niche through the facial recess performed on a cadaver head, an electrode array from a Nucleus Softip Contour CI was fully inserted through a cochleostomy. The head was then scanned axially on a 64-slice MDCT with 0.4-mm slice thickness and reconstructed into the oblique axial, oblique coronal, and oblique sagittal planes of the cochlea. The temporal bone was then harvested and imaged on a microcomputed tomographic scanner using 20-microm slice thickness. Identical reconstructions were made and compared with the 64-slice images to confirm exact location of the electrode array. The 64-slice MDCT accurately localized the electrode array to the scala tympani. This was best demonstrated in the oblique sagittal plane, identifying the electrode array in the posterior inferior portion of the basal turn, posterior to the spiral lamina. This ex vivo validation study suggests that 64-slice MDCT has the potential to allow accurate localization of the CI electrode array within the basal turn of the cochlea.

Arcuate ligament of the wrist: normal MR appearance and its relationship to palmar midcarpal instability: a cadaveric study

To describe the magnetic resonance (MR) imaging and gross anatomic appearance of the scaphocapitate (SC) ligament and triquetrohamocapitate (THC) ligament, which are the radial and ulnar limbs of the composite arcuate ligament, a critical volar midcarpal stabilizing ligament. T1 spin-echo and 3D gradient-echo MR imaging in the standard, coronal oblique, and axial oblique planes were performed both before and following midcarpal arthrography in seven cadaveric wrists. The seven specimens were then sectioned in selected planes to optimally visualize the SC and THC ligaments. These specimens were analyzed and correlated with their corresponding MR images. The SC and THC ligaments can be visualized in MR images as structures of low signal intensity that form an inverted "V" joining the proximal and distal carpal rows. The entire ligamentous complex is best visualized with coronal and axial oblique MR imaging but can also be seen in standard imaging planes. SC and THC ligaments together form the arcuate ligament of the wrist. Their function is crucial to the normal functioning of the wrist. Palmar midcarpal instability (PMCI) is a resulting condition when abnormalities of these ligaments occur. Dedicated MR imaging in the coronal and axial imaging planes can be performed in patients suspected of having PCMI.

１６ＤＡＳ‐ＭＤＣＴ使用のＭＰＲ画像における角度変化に伴う解像度評価

In this study, we evaluated the resolving power of three-dimensional (3D) multiplanar reformation (MPR) images with various angles by using 16 data acquisition system multi detector row computed tomography (16DAS-MDCT) . We reconstructed the MPR images using data with a 0.75 mm slice thickness of the axial image in this examination. To evaluate resolving power, we used an original new phantom (RC phantom) that can be positioned at any slice angle in MPR images. We measured the modulation transfer function (MTF) by using the methods of measuring pre-sampling MTF, and used Fourier transform of image data of the square wave chart. The scan condition and image reconstruction condition that were adopted in this study correspond to the condition that we use for three-dimensional computed tomographic angiography (3D-CTA) examination of the head in our hospital. The MTF of MPR images showed minimum values at slice angles in parallel with the axial slice, and showed maximum values at the sagittal slice and coronal slice angles that are parallel to the Z-axis. With an oblique MPR image, MTF did not change with angle changes in the oblique sagittal slice plane, but in the oblique coronal slice plane, MTF increased as the tilt angle increased from the axial plane to the Z plane. As a result, we could evaluate the resolving power of a head 3D image by measuring the MTF of the axial image and sagittal image or the coronal image.