Joong Mo Ahn

Risk Factors of New Compression Fractures in Adjacent Vertebrae after Percutaneous Vertebroplasty

Purpose: To evaluate the risk factors related to the development of new fractures in adjacent vertebrae after vertebroplasty. Material and Methods: The study was conducted on 106 patients in whom 212 vertebroplasties were performed during a period of 3 years. Evaluations of the five vertebrae superior and inferior to the treated vertebra were performed. Consequently, 913 vertebrae were evaluated and the fracture‐free interval of the vertebral body adjacent to the treated vertebra was calculated. Survival analysis was performed using the Kaplan‐Meier method and Cox proportional hazards regression analysis. Results: Seventy‐two (7.9%) new fractures were revealed. The Kaplan‐Meier estimate of the 1‐year fracture‐free rate was 93.1%. The mean fracture‐free interval was 32 months (95% CI, 32∼33 months). The greater degree of height restoration of the treated vertebra, the location of the adjacent vertebra in the TL junction, and the shorter distance between the treated and the adjacent vertebra increased the risk of new vertebral fractures. Conclusion: Thoracolumbar junction, shorter distance from the treated vertebrae, and greater degree of height restoration of the cemented vertebrae may increase the fracture risk of vertebrae adjacent to cement vertebrae after vertebroplasty.

Lung cancer in patients with idiopathic pulmonary fibrosis: CT findings.

PURPOSE The frequency of lung cancer in patients with idiopathic pulmonary fibrosis (IPF) is higher than that of general population. To evaluate CT findings of lung cancer associated with IPF, we analyzed 32 patients with lung cancer associated with IPF. METHOD We analyzed retrospectively 32 patients with histologically confirmed lung cancer out of 244 consecutive cases diagnosed as IPF by either CT and clinical findings (n = 220) or histologically (n = 24). The patients were 40-85 years old (mean 66 years, M/F = 31/1). Scanning techniques were conventional CT in 24 patients, high-resolution CT (HRCT) in 2 patients, and both conventional CT and HRCT in 6 patients. We analyzed the CT patterns, locations, and histologic types of lung cancer. RESULTS The frequency of lung cancer in patients with IPF was 13.1% (32/244). In 17 of 32 patients, the CT findings of lung cancer were ill defined lesions mimicking air-space consolidation. Lung cancer was located mainly in the lower lobes (21/32) and peripheral portion (21/32). Histologically, squamous cell carcinoma was the most common type (18/32). CONCLUSION Typical CT findings of lung cancer were ill defined consolidation-like masses at the peripheral portion where the most advanced fibrosis was located.

Tibiofibular syndesmosis: high-resolution MRI using a local gradient coil.

PURPOSE Our goal was to correlate high-resolution MR images of the tibiofibular syndesmosis with anatomic sections. METHOD MRI was performed inside a local gradient coil on six cadaveric feet taped in 10-20 degrees dorsiflexion and 40-50 degrees plantar flexion by using axial and coronal T1-weighted SE sequences. After imaging, the specimens were frozen and sectioned into 3-mm-thick slices along the MR planes. Images were correlated with the anatomic sections. RESULTS MRI depicted the anatomy of the tibiofibular syndesmosis and surrounding structures. With the foot taped in dorsiflexion, axial imaging provided optimum views of the anterior, posterior, interosseous, and transverse tibiofibular ligaments. Coronal images allowed visualization of the entire course of the anterior, posterior, and transverse tibiofibular ligaments. The multifascicular appearance of the anterior tibiofibular ligament was best visualized in coronal sections. With the foot taped in dorsiflexion or in plantar flexion, it was possible to distinguish the posterior tibiofibular ligament and transverse tibiofibular ligament from the posterior talofibular ligament in all specimens. CONCLUSION High-resolution MRI using a local gradient coil provides excellent delineation of the ligaments of the distal tibiofibular syndesmosis.

Adhesive capsulitis of the shoulder: diagnosis using magnetic resonance arthrography, with arthroscopic findings as the standard.

ObjectiveThe purpose of this study was to assess the usefulness of magnetic resonance (MR) arthrography of the glenohumeral joint in the diagnosis of adhesive capsulitis. MethodsMR arthrography of the glenohumeral joint was performed in 16 patients with arthroscopically proven adhesive capsulitis and 11 controls. Thickness of the joint capsule and synovium, filling ratio of the fluid-distended axillary recess to the posterior joint cavity, and a width of the rotator cuff interval were measured by 2 musculoskeletal radiologists. The measurements of those parameters for the patients with adhesive capsulitis and the controls were compared. Interobserver variability for the measurements of each parameter was calculated. ResultsThe mean thickness of the joint capsule and synovium was 2.97 mm in patients with adhesive capsulitis and 1.86 mm in controls (P < 0.001). The mean filling ratio of the fluid-distended axillary to the posterior joint cavity was 0.51 in patients with adhesive capsulitis and 0.82 in controls (P = 0.004). The mean width of the rotator cuff interval was 7.45 mm in patients with adhesive capsulitis and 8.48 mm in controls (P > 0.05). Intraclass correlation coefficient for interobserver variability showed good agreement (95% CI; 0.72–0.95). ConclusionsOn MR arthrography, thickening of the joint capsule and synovium and diminished filling ratio of the axillary recess to posterior joint cavity appeared to be useful diagnostic criteria for the diagnosis of adhesive capsulitis of the shoulder.

Analysis of patellar cartilage: Comparison of conventional MR imaging and MR and CT arthrography in cadavers

Objective: To compare the sensitivity of conventional MR sequences, MR arthrography, and CT arthrography for the detection of cartilage lesions of the patella in cadavers. Material and Methods: Cartilage lesions in 10 cadaveric specimens were evaluated by MR imaging, including T1-weighted, proton density-weighted and T2-weighted sequences, and fat-suppressed spoiled gradient recalled acquisition in the steady state (SPGR), MR arthrography including T1-weighted and SPGR sequences, and double-contrast CT arthrography including conventional and subtracted images. The sensitivities with regard to detection of lesions were compared to results from morphologic and histologic investigations of sectioned specimens. Results: Twenty-one lesions were detected morphologically. For the detection of these lesions, sensitivities were as follows: T1-weighted images 33.3%; proton density-weighted images 85.7%; T2-weighted images 85.7%; SPGR images 80.9%; MR arthrography with T1-SE sequences 57.1%; MR arthrography with SPGR sequence 90.5%; and CT arthrography, both regular and subtracted images 85.7%. Conclusion: For noninvasive techniques, T2-weighted images revealed the highest sensitivity for the detection of patellar cartilage lesions, which was surpassed only by MR arthrography using the SPGR sequence. CT arthrography delineated surface irregularities but failed to demonstrate intrachondral lesions.

Pulmonary nocardiosis : CT findings

Objective To evaluate CT findings of pulmonary nocardiosis in immunocompromised patients. Materials and Methods Five patients with bacteriologically confirmed pulmonary nocardiosis were evaluated. Four patients were receiving corticosteroids with or without other immunosuppressive drugs for lupus nephritis (two patients), idiopathic thrombocytopenic purpura (one patient), and renal transplantation (one patient), and one patient had long-standing diabetes. Nocardia asteroides was isolated from blood culture, bronchial washing, pleuropulmonary aspirates, or open lung biopsy. Plain chest radiography and CT were performed on all patients, and follow-up CT was performed on one patient. Results On CT there were pleural effusion (four patients), air-space consolidation with internal low attenuation with or without cavities (four patients), multiple noncavitating pulmonary nodules and subpleural pulmonary nodules (three patients), and chest wall extension (three patients). Follow-up CT after treatment showed marked improvement of the pleural and pulmonary lesions. Conclusion In the immunocompromised and chronically debilitated host, pulmonary nocardiosis should be included in differential diagnosis if chest CT shows consolidation with low attenuation areas with or without cavitation, multiple pulmonary nodules, pleural effusion, and chest wall extension.

Transverse ligament and its effect on meniscal motion. Correlation of kinematic MR imaging and anatomic sections.

RATIONALE AND OBJECTIVES To evaluate the effect of the transverse ligament on translation of the menisci. METHODS Six cadaveric knees were examined by MR imaging inside a positioning device before and after transecting the transverse ligament. The knees were examined at various positions: extension, 30 degrees of flexion, 60 degrees of flexion, and full flexion. Sagittal T1-weighted spin-echo images were generated at each knee position and evaluated for statistical differences with regard to anterior-posterior meniscal excursion. RESULTS Statistically significant differences in meniscal excursion were found before and after transsecting the transverse ligament for anterior-posterior meniscal motion of the anterior horn of the medial meniscus at 30 degrees of knee flexion. No such significant differences were found, however, at 60 degrees of flexion and full flexion in anterior-posterior meniscal excursion of the anterior or posterior horn of either meniscus before and after transsecting the transverse ligament. CONCLUSIONS The transverse ligament has a restricting effect on anterior-posterior excursion of the anterior horn of the medial meniscus at lower degrees of knee flexion.

Predicting the histology of anterior mediastinal masses: comparison of chest radiography and CT.

The objective of this study was to compare chest radiography with computed tomography (CT) in the prediction of a specific diagnosis in adult patients with anterior mediastinal masses. Chest radiographs and CT scans of 128 patients with anterior mediastinal masses were randomized and analyzed retrospectively by two independent observers. The observers listed the three most likely diagnoses in order of probability and recorded the degree of confidence in their first-choice diagnosis. Findings from chest radiographs and CT scans were recorded by each observer and used for a stepwise discriminant analysis between diagnoses. Results showed that the correct first-choice diagnosis, regardless of the degree of confidence, was made in 36% of chest radiographs and 48% of CT scans (p < 0.05). The correct diagnosis was included among top three diagnoses in 59% and 72% of the studies, respectively (p < 0.001). A high confidence diagnosis (level 1) was reached in 9% and 34% of each study, respectively, (p < 0.001), and was correct in 58% and 80% of the studies, respectively. Interobserver agreement (k statistics) on the correct first-choice diagnosis was 0.45 and 0.53, respectively. Interpretations of the CT scans were most often accurate in the confident diagnosis of benign germ cell tumors (n = 10, 100%), thymolipomas (n = 3, 100%), and omental hernia (n = 2, 100%). Seven of 15 radiographic findings and 11 of 22 CT findings were discriminant. We conclude that although CT is better then chest radiography in determining the pathologic diagnosis of an anterior mediastinal mass, CT is still poor at making that prediction with confidence. However, several anterior mediastinal masses could be diagnosed accurately by CT.

A New MRI Grading System for Cervical Foraminal Stenosis Based on Axial T2-Weighted Images.

Objective The purpose of this study was to evaluate the reliability of a new magnetic resonance imaging (MRI) grading system for cervical neural foraminal stenosis (NFS). Materials and Methods Cervical NFS at bilateral C4/5, C5/6, and C6/7 was classified into the following three grades based on the T2-weighted axial images: Grade 0 = absence of NFS, with the narrowest width of the neural foramen greater than the width of the extraforaminal nerve root (EFNR); Grade 1 = the narrowest width of the neural foramen the same or less than (but more than 50% of) the width of the EFNR; Grade 2 = the width of the neural foramen the same or less than 50% of the width of the EFNR. The MRIs of 96 patients who were over 60 years old (M:F = 50:46; mean age 68.4 years; range 61-86 years) were independently analyzed by seven radiologists. Interobserver and intraobserver agreements were analyzed using the percentage agreement, kappa statistics, and intraclass correlation coefficient (ICC). Results For the distinction among the three individual grades at all six neural foramina, the ICC ranged from 0.68 to 0.73, indicating fair to good reproducibility. The percentage agreement ranged from 60.2% to 70.6%, and the kappa values (κ = 0.50-0.58) indicated fair to moderate agreement. The percentages of intraobserver agreement ranged from 85.4% to 93.8% (κ = 0.80-0.92), indicating near perfect agreement. Conclusion The new MRI grading system shows sufficient interobserver and intraobserver agreement to reliably assess cervical NFS.

Evaluation of the triangular fibrocartilage and the scapholunate and lunotriquetral ligaments in cadavers with low-field-strength extremity-only magnet. Comparison of available imaging sequences and macroscopic findings.

RATIONALE AND OBJECTIVES The authors assessed the ability of a low-field-strength extremity-only magnet to provide visualization of the triangular fibrocartilage and the scapholunate and lunotriquetral ligaments. METHODS Twelve human wrists were examined with a 0.2 T extremity-only magnet. T1-weighted spin echo, proton density-weighted, and T2-weighted turbo spin echo, short-tau inversion recovery, and three-dimensional gradient recalled echo images were acquired, and sections of the specimens were then made that corresponded to the magnetic resonance images. Masked imaging analyses were correlated with macroscopic and limited histopathologic findings. RESULTS Low-field-strength extremity-only magnet allowed consistent visualization of the triangular fibrocartilage and accurate assessment of a small number of complete tears of the triangular fibrocartilage. The scapholunate ligaments in all cases were identified using a combination of imaging sequences. Consistent visualization of the lunotriquetral ligament with a low-field-strength extremity magnet was difficult. CONCLUSIONS Magnetic resonance imaging with a low-field-strength extremity-only magnet can be used to visualize the triangular fibrocartilage and the scapholunate ligament, but not the lunotriquetral ligament.