Oblique Axial Planes Research Articles

Capsular elongation in shoulders with recurrent anterior dislocation. Quantitative assessment with magnetic resonance arthrography.

Elongation of the shoulder capsule is often noticed on arthrograms or during surgery in shoulders of patients who have experienced recurrent anterior dislocations. We can quantify the elongation of the capsule in shoulders with recurrent anterior dislocations by using magnetic resonance arthrography. Retrospective review of prospectively collected data. Twelve patients with unilateral recurrent anterior shoulder dislocations were enrolled in this study. Magnetic resonance images in the axial and coronal oblique planes were obtained from both shoulders (involved and uninvolved sides) after 10 ml of gadolinium/saline solution was injected into the glenohumeral joint. The length of the anteroinferior, inferior, and posteroinferior portions of the capsule was measured by using image analyzing software and normalized to the humeral head diameter. The anteroinferior capsule was significantly elongated in the involved shoulder at 4 mm (16% elongation) and 10 mm (19% elongation) superior to the inferior margin of the glenoid. The inferior capsule was also significantly elongated in the involved side both at the center (12% elongation) and at 4 mm anterior to the center of the glenoid (29% elongation). The posteroinferior capsule did not show any significant elongation. The anteroinferior and inferior portions of the shoulder capsule are elongated an average of 19% in shoulders with recurrent anterior dislocation.

Malalignment at the Lisfranc joint: MR features in asymptomatic patients and cadaveric specimens.

To assess the frequency of malalignment in the 1st, 2nd and 3rd tarso-metatarsal joints (Lisfranc joint) in cadaveric specimen and asymptomatic individuals utilizing oblique axial MR images. Four fresh frozen cadaveric feet were dissected in the oblique axial plane at 5 mm slice thickness. Thirty MR studies in 29 patients who had no history of pain, trauma or surgery at the tarso-metatarsal area were included in our study. The 1st to 3rd tarso-metatarsal joints were evaluated on the MR studies and cadaveric slices by two musculoskeletal radiologists for (1) the presence of a medial and/or lateral step-off and (2) articular surface divergence. In the cadaveric dissections there were lateral step-offs in the 1st ( n=3) and in the 2nd ray ( n=3) respectively. No joint incongruity was evidenced. The MR studies in the patients population depicted 28 step-offs (9 medial, 19 lateral) in the 1st ray, 16 (2 medial, 14 lateral) in the 2nd ray and two in the 3rd ray. Joint incongruity was present in the 2nd ray ( n=6) and in the 3rd ray ( n=12). All the above findings were limited to a few images. Isolated joint malalignment with otherwise normal findings (no ligamentous injury, no fracture and no bone marrow edema) might reflect normal anatomic features at the tarso-metatarsal joints and must be interpreted carefully.

Dominancia hemisférica para el lenguaje y resonancia magnética funcional: comparación de tres tareas

The object of this study to analyse and compare the efficacy of the classic language tasks (repetition, phonological fluency and lexical decision), for the purpose of identifying the dominant hemisphere for language by means of functional magnetic resonance. The three tasks were performance with a groups of 10 right handed subjects with ages of 22 to 40 years. The examination was carried out using a 1,5 T MRI apparatus. An eight sequence of planar echo gradient (BOLD technique) was used, making the oblique axial plane coincide with the line between the anterior and posterior commissures (CA CP line) and covering the entire brain. Dominance was calculated by means of the lateralization index, comparing the activation in each hemisphere in two locations: first, taking account the temporal lobe together with the right and left frontal lobes, and second, taking into account only the right and left frontal lobes. The result indicate that the most effective test for obtaining the dominant hemisphere was the one for phonological fluency, this task activated the frontal areas, which showed greater participation in the left hemisphere.

Magnetic resonance imaging of reconstructed anterior cruciate ligament.

After anterior cruciate ligament reconstruction with autologous patellar tendon, 23 patients who had clinically stable knees were studied prospectively with sequential magnetic resonance imaging 1, 2, 3, 6, and 12 months after surgery. The images of the anterior cruciate ligament were obtained with a 1.5 tesla magnetic resonance scanner in the oblique sagittal, coronal, and oblique axial planes. The cross-sectional area and signal intensity on the reconstructed anterior cruciate ligament were measured in an oblique axial image. The usefulness of the oblique axial image in evaluating the integrity of the reconstructed anterior cruciate ligament was seen. The result showed that the diameter of the graft increased by 70% of its initial size and the signal intensity of the reconstructed graft also showed a tendency to increase. In three patients, there was discontinuity in the graft direction on the oblique sagittal image, but on the oblique axial image there was no evidence of reconstructed anterior cruciate ligament rupture in the sequential images. This shows the value of the oblique axial image in evaluating the integrity of the reconstructed anterior cruciate ligament. Also, sufficient notchplasty in anterior cruciate ligament reconstruction may be needed to prevent graft impingement.

Magnetic resonance arthrography of the acetabular labrum: value of radial reconstructions.

The intention was to compare the sensitivity and specificity of radial planes with oblique coronal and oblique axial planes for the detection of labral abnormalities of the acetabulum on magnetic resonance arthrography (MRa). Twenty cadaveric hip joints were examined by radiography and MRa. For MRa, 15 ml of a solution of iodinated contrast material and gadolinium diethylene triamine tetra-acetic acid (Gd-DTPA; 100:1) were injected under fluoroscopic guidance. MRI was performed on a 1.5-T MR scanner with a fat-suppressed 3D-FLASH sequence (TR/TE/flip-angle 42 ms/10 ms/40 degrees; field of view 16 cm, matrix 256 x 256, section thickness 1.5 mm, pixel size 0.7 x 0.7 mm). Multiplanar image reconstructions were done perpendicular to the acetabulum in oblique coronal and oblique axial planes and in radial planes. Macroscopic and histopathologic examination of the labral specimens was performed. Labral lesions were found in 15/20 hips (75%) on pathologic examination. Six hips demonstrated labral degeneration. The labrum was partially detached in 7 hips and completely detached in 2 hips. A flap-like labrum was found in 2 cases, 1 with partial detachment of the labrum and 1 with a degenerated labrum. Using oblique coronal and oblique axial reconstructions, pathologic findings were confirmed by MRa in 9/15 specimens (sensitivity 60%). There were no false-positive findings (specificity 100%, accuracy 70%). Also, 3/6 labral degenerations without detachment, 4/7 partial detachments, and 2/2 complete detachments were correctly diagnosed. Two flap-like labra were not recognized. With radial reconstructions, pathologic findings were correctly confirmed in 12/15 specimens (sensitivity 80%) without false-positive findings (specificity 100%, accuracy 85%). Also, 3/6 labral degenerations without detachment, 6/7 partial detachments, 2/2 complete detachments, and 1/2 flap-like labra were correctly diagnosed. MRa of the acetabular labrum using radial reconstructions is well suited to delineate the acetabular labrum and to diagnose labral detachments. Radial reconstructions allow for perpendicular display of the whole acetabular circumference and are more accurate for the diagnosis of acetabular labral lesions, when compared with oblique coronal and oblique axial reconstructions.

Posteromedial corner of the knee: MR imaging with gross anatomic correlation

The objective of this study was to illustrate the magnetic resonance (MR) image appearance of the structures of the posteromedial "corner" of the knee with particular emphasis on the anatomy and differentiation between the medial collateral ligament and the posterior oblique ligament. Six cadaveric knee specimens underwent MR imaging, before and following instillation of intra-articular contrast material. The knees were sectioned in the axial, coronal, and coronal oblique planes and the gross morphology of the posteromedial corner and surrounding structures was studied and correlated with the MR images. The human cadaveric specimens were from two female and four male patients (age at death, 72-86 years; average, 78 years). The contrast-enhanced sequences and the coronal oblique images allowed for improved visualization of the structures.

Efficacy of MR Arthrography in the Diagnosis of the Acetabular Labral Tear

Purpose : To determine the accuracy of magnetic resonance (MR) arthrography in the detection and staging of lesions of the acetabular labrum. Materials and Methods : Fifteen hips of 14 patients with chronic hip pain and clinical suspicion of labral lesions were examined with direct or indirect MR arthrography and underwent subsequent arthroscopic evaluation. The study population consisted of six women and eight men aged between 40 and 59 years. Nine arthrograms were obtained intra-articular administration of gadolinium solution, and six involved articular motion exercise after intravenous administration of gadolinium solution. In 14 cases a phased-array pelvic coil was used, and a shoulder coil in one. Fat-suppressed T1-weighted images were obtained in the coronal, oblique coronal and oblique axial planes, and T1-and T2-weighted images were obtained in the axial plane. Labral lesions were graded according to the Czerny classification and evaluated on the basis of presence or absence of a tear and lo-cation (anteroinferior, anterosuperior, superior, posterosuperior, posteroinferior). The findings were then cor-related with the arthroscopic findings. Results : After direct and indirect MR arthography, the findings-based on the Czerny classification -were as follows : stage IA:3; IB:1; IIA:8; IIB:1; IIIA:4; IIIB:0. MR arthrography also showed that seven cases were locat-ed in the anterosuperior portion of the labrum, seven in the superior portion, and three in the posteroinferior portion. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR arthrography for diagnosis of the labral tear was 92%, 75%, 92%, 75 %, and 88 %, respectively. Conclusion : In this preliminary study, MR arthrography appears to be a promising imaging modality for accu-rate diagnosis and useful for screening patients with chronic hip pain.

Dual oblique MR method for imaging the sciatic nerve.

We present an alternative imaging technique for evaluation of the sacral plexus and sciatic nerve. Images were obtained in the oblique coronal, oblique sagittal, and oblique axial planes using the piriformis muscle as the initial reference point. Evaluation of the sciatic nerve is optimized by the multiplanar capability of MRI.

Ligaments of the ankle: normal anatomy with MR arthrography.

Our purpose was to define the normal MR arthrographic anatomy of ankle ligaments. Prior to injection of intraarticular gadolinium in cadaveric ankle joints, proton density and T2-weighted images were obtained to assess the integrity of the ligaments and tendons as well as the amount of preexisting joint effusion. Following injection of 10 ml of contrast agent (gadopentetate dimeglumine 1:250, Omnipaqe 300, Knox gelatin 50%, and methylene blue), T1-weighted images with fat saturation in axial, oblique axial, coronal, and sagittal planes were obtained in neutral, dorsiflexion, and plantar flexion positions. Specimens were sectioned, allowing anatomic and MR correlation. Contrast agent outlining anterior and posterior aspects of the anterior talofibular ligament and posterior talofibular ligament (PTAF) was a normal finding, related to anterior and posterior recesses of the ankle joint that extend out beyond these ligaments in an anteroposterior direction above the level of the ligaments. Intraarticular contrast material allowed resolution of superficial and deep components of the posterior tibiofibular ligament. Both were seen separately from PTAF with dorsiflexion. Posterior intermalleolar ligament was not present in our specimens. Visualization of calcaneofibular ligament was much improved by contrast material outlining the articular aspect of the ligament. Visualization of the syndesmotic ligamentous complex also was improved by contrast material outlining the articular side of the ligaments and separating them from adjacent bone. Superiorly, the distribution of contrast agent was limited by the interosseous ligament. Visualization of the medial collateral ligaments was not improved by the presence of the intraarticular contrast material. MR arthrography of the ankle allows improved visualization and evaluation of the lateral and syndesmotic ligamentous complex.

Anatomic and physiologic measurements of the internal and external anal sphincters in normal females

Objective: To assess the correlation between anal sphincter magnetic resonance imaging (MRI) measurements and manometric anorectal vectography pressures. Methods: Ten healthy, nulliparous women underwent anal sphincter MRI with examination of sagittal, axial oblique, and coronal planes. Anal manometry was performed with a radial eight-channel catheter. Customary functional measurements were recorded, including anterior and posterior sphincter length, squeeze length, length of the high-pressure zone, and maximal resting and squeeze pressures. The Spearman rank correlation coefficient was used to assess correlation. Results: The manometric squeeze length and the manometric length to maximum squeeze pressure were correlated negatively with the posterior sphincter length by MRI ( P = .049 and .044, respectively). The manometric high-pressure zone squeeze length was correlated positively with the posterior sphincter length by MRI ( P = .042). The mean ± standard deviation (SD) posterior sphincter length was 27.3 ± 6.0 mm. Anatomically, the cylindric shape of the anal sphincter is characterized by a gradual increase in muscle thickness cephalad. The external striated sphincter was much thicker posteriorly (24.7 ± 4.6 mm) than anteriorly (6.6 ± 1.7 mm) in the proximal or caudal third. The proximal internal smooth muscle sphincter was nearly equal in thickness anteriorly and posteriorly (9.0 ± 1.4 mm and 9.6 ± 1.7 mm, respectively). Although variation in the thickness of both the smooth and striated muscle was found, manometric pressures did not correlate with the muscle thickness along the sphincter. Conclusion: The length of the anal sphincter correlated positively with the functional information, as determined by manometry. An anal sphincter length of 3 cm is consistent, from an anatomic and functional view, in these ten normal women.

Auditory cortex activation in deaf subjects during cochlear electrical stimulation. Evaluation by functional magnetic resonance imaging.

The authors detect activation in the auditory cortex during cochlear electrical stimulation in deaf patients using functional magnetic resonance (MR) imaging. Stimulating electrode was inserted gently under local anesthesia close to the round window membrane of the cochlea in seven cochlear implant candidates. These patients suffered from postlingual-acquired deafness. Four patients were stimulated above the electrical perception threshold and three below the electrical discomfort threshold. Functional scans (fast low-angle shot 91 mseconds/60 mseconds) were acquired in an oblique axial plane running parallel to the sylvian fissure. Four consecutive series of six images were obtained in 6 minutes. The acquisition time of each image was 15 seconds. During electrical cochlear stimulation below the discomfort threshold, the three patients described "auditory" sensations with activation of the superior temporal regions. In two patients with electrical stimulation of the left ear, the maximum signal intensity increased by 8.42% in the right auditory cortex and 5.69% in the left. In one patient with a right electrical stimulation only the left cortex was activated. Electrical cochlear stimulation above the perception threshold induces no significant activation in the auditory cortex. Functioning MR imaging can detect activation in the auditory cortex during cochlear electrical stimulation in deaf patients using a conventional 1.5-tesla system in a routine hospital environment. Further studies are needed to investigate its usefulness in clinical practice.

The diagnostic value of MRI in traumatic brachial plexus injury

Findings in 34 patients with traumatic brachial plexus injury documented by surgical exploration and intra-operative somatosensory-evoked potentials were correlated with findings on myelography and magnetic resonance imaging (MRI) to determine whether MRI can identify nerve root avulsion. The coronal and sagittal planes were not able to demonstrate avulsion of the individual nerve roots. The axial and axial oblique planes did provide useful information to determine which nerve root was avulsed in the upper plexus, although it was difficult to clearly delineate the lower cervical rootlets. The accuracy of MRI was 73% for C5 and 64% for C6 and that of myelography 63% for C5 and 64% for C6. Thus, the diagnostic accuracy of MRI for upper nerve roots was slightly superior to myelography. Although its primary diagnostic value is limited to the upper nerve roots whose avulsion is relatively difficult to diagnose by myelography, MRI can provide useful guidance in the waiting period prior to surgical exploration after brachial plexus injury.

Do abnormalities of the frontonasal duct cause frontal sinusitis? A CT study in 198 patients.

The purpose of the study was to determine the correlation between frontonasal duct abnormalities (narrowing or obstruction caused by hypertrophic mucosa) and frontal sinusitis. This study was based on the hypothesis that abnormalities of the frontonasal duct cause frontal sinusitis by impairing normal drainage of the sinus. CT studies of 198 consecutive patients with clinical diagnoses of chronic sinusitis were reviewed retrospectively. Criteria for inclusion were (1) no history of sinus surgery or facial trauma and (2) absence of polyps at rhinoscopy. As 37 frontal sinuses were undeveloped, a total of 359 sinuses were evaluated. CT scans were obtained in oblique axial and coronal planes. The following CT features were assessed: (1) the frequency of detection of the frontonasal duct, (2) the appearance of the frontonasal duct: normal vs abnormal (narrowed or obstructed), and (3) the correlations between abnormalities of the frontonasal duct and frontal sinusitis. The frontonasal duct was detected in all 359 cases, either in both CT planes (81%) or only in the axial oblique plane (19%). In 267 (74%) of 359 cases, the duct appeared normal; among these, isolated frontal sinusitis was detected in five cases (2%). In 92 (26%) of 359 cases, the duct was abnormal; it was narrowed in 18 cases (5%) and obstructed in 74 cases (21%). Frontal sinusitis was noted in 78 (85%) of the 92 cases of frontonasal duct abnormalities. The sensitivity and specificity of the correlations between frontonasal duct abnormalities and frontal sinusitis were 98% and 85%, respectively. Because our results show a strong correlation between abnormalities of the frontonasal duct and frontal sinusitis, it seems highly probable that abnormalities of the frontonasal duct cause frontal sinusitis.

MR evaluation of brachial plexus injuries.

Ten cases of brachial plexus injury were subjected to magnetic resonance (MR) to demonstrate the roots, trunks, divisions or cord abnormalities. Both normal and abnormal brachial plexuses were imaged in sagittal, axial, coronal and axial oblique planes. Myelography, using water soluble contrast agents, was performed in seven cases. MR demonstrated one traumatic meningocele, one extradural cerebrospinal fluid (CSF) collection, trunk and/or root neuromas in four, focal root fibrosis in two and diffuse fibrosis in the remaining two cases. Results of MR were confirmed at surgery in four cases with neuromas, while myelography was normal in two and was not carried out in the remaining two. In two cases, where MR demonstrated diffuse fibrosis of the brachial plexus, myelography showed C7 and T1 traumatic meningocele in one and was normal in the other. Both these patients showed excellent clinical and electrophysiological correlation with MR findings and in one of them surgical confirmation was also obtained. In the other two cases with focal nerve root fibrosis, myelography was normal in one and showed a traumatic meningocele in another. Operative findings in these cases confirmed focal root fibrosis but no root avulsion was observed although seen on one myelogram. Focal fibrosis, however, was noted at operation in more roots than was observed with MR. Initial experience suggests that MR may be the diagnostic procedure of choice for complete evaluation of brachial plexus injuries.

Quantitation of digital clubbing by shadowgram technique.

Finger clubbing was quantified from the magnified silhouette of the right index finger in controls and patients with clubbing, using a simple shadowgram technique. There was good correlation between clinical assessment and measurement of both the profile angle and the hyponychial angle. The hyponychial angle appeared to be a more accurate indicator of clubbing than the profile angle.