Heung Sik Kang

Pulmonary Cement Embolism after Percutaneous Vertebroplasty in Osteoporotic Vertebral Compression Fractures: Incidence, Characteristics, and Risk Factors

PURPOSE To prospectively evaluate the incidence of, characteristics of, and risk factors for pulmonary cement embolism after percutaneous vertebroplasty (PVP) in osteoporotic vertebral compression fractures (VCFs). MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. From June 2006 to September 2007, 75 patients (57 women, 18 men; mean age, 74.78 years; range, 48-93 years) who underwent 78 PVP sessions at 119 levels for osteoporotic VCFs were prospectively enrolled in this study. Computed tomographic (CT) scans of the chest and treated vertebrae were obtained after PVP. The presence, location, involved pulmonary arteries, number, and size of each pulmonary cement embolus were analyzed at CT. Possible risk factors were analyzed as follows: Age, injected cement volumes, and numbers of treated vertebrae were analyzed by using the Mann-Whitney U test; operators (radiologist or nonradiologist), level of treated vertebrae, guidance equipment, approach (uni- or bipedicular), presence of intravertebral vacuum clefts, and presence of paravertebral venous leakage were analyzed by using Pearson chi(2) and Fisher exact tests. RESULTS Pulmonary cement emboli developed in 18 (23%) of 78 PVP sessions and were detected in the distal to third-order pulmonary arteries. Only cement leakage into the inferior vena cava showed a statistically significant relationship to pulmonary cement embolism (P = .03). A higher frequency of pulmonary cement embolism was noted for the absence of intravertebral vacuum clefts, for the bipedicular approach, and for a nonradiologist operator with C-arm fluoroscopy (P > .05). CONCLUSION In osteoporotic VCFs, pulmonary cement embolism was detected in 23% of PVP sessions, developed in the distal to third-order pulmonary arteries, and was related to leakage into the inferior vena cava.

A Practical MRI Grading System for Lumbar Foraminal Stenosis

OBJECTIVE This study aimed to evaluate the reproducibility of a new grading system for lumbar foraminal stenosis. MATERIALS AND METHODS Four grades were developed for lumbar foraminal stenosis on the basis of sagittal MRI. Grade 0 refers to the absence of foraminal stenosis; grade 1 refers to mild foraminal stenosis showing perineural fat obliteration in the two opposing directions, vertical or transverse; grade 2 refers to moderate foraminal stenosis showing perineural fat obliteration in the four directions without morphologic change, both vertical and transverse directions; and grade 3 refers to severe foraminal stenosis showing nerve root collapse or morphologic change. A total of 576 foramina in 96 patients were analyzed (from L3-L4 to L5-S1). Two experienced radiologists independently assessed the sagittal MR images. Interobserver agreement between the two radiologists and intraobserver agreement by one reader were analyzed using kappa statistics. RESULTS According to reader 1, grade 1 foraminal stenosis was found in 33 foramina, grade 2 in six, and grade 3 in seven. According to reader 2, grade 1 foraminal stenosis was found in 32 foramina, grade 2 in six, and grade 3 in eight. Interobserver agreement in the grading of foraminal stenosis between the two readers was found to be nearly perfect (kappa value: right L3-L4, 1.0; left L3-L4, 0.905; right L4-L5, 0.929; left L4-L5, 0.942; right L5-S1, 0.919; and left L5-S1, 0.909). In intraobserver agreement by reader 1, grade 1 foraminal stenosis was found in 34 foramina, grade 2 in eight, and grade 3 in seven. Intraobserver agreement in the grading of foraminal stenosis was also found to be nearly perfect (kappa value: right L3-L4, 0.883; left L3-L4, 1.00; right L4-L5, 0.957; left L4-L5, 0.885; right L5-S1, 0.800; and left L5-S1, 0.905). CONCLUSION The new grading system for foraminal stenosis of the lumbar spine showed nearly perfect interobserver and intraobserver agreement and would be helpful for clinical study and routine practice.

Radiologic Diagnosis of Osteoid Osteoma: From Simple to Challenging Findings

Osteoid osteoma is characterized by an intracortical nidus with a variable amount of calcification, as well as cortical thickening, sclerosis, and bone marrow edema. When these findings are present, a diagnosis of osteoid osteoma is easily made. However, osteoid osteoma may display imaging findings that can be misleading, and it can be difficult to differentiate osteoid osteoma from other conditions such as infection, inflammatory and noninflammatory arthritis, and other tumors. In addition, stress fracture, intracortical abscess, intracortical hemangioma, chondroblastoma, osteoblastoma, and compensatory hypertrophy of the pedicle may mimic osteoid osteoma. To make the correct diagnosis, it is necessary to identify the nidus, and it is important to be familiar with the radiologic findings of osteoid osteoma and its mimics.

MR Imaging Assessment of the Spine: Infection or an Imitation?

Magnetic resonance (MR) imaging is a powerful diagnostic tool that can be used to help evaluate spinal infection and to help distinguish between an infection and other clinical conditions. In most cases of spinal infection, MR images show typical findings such as vertebral endplate destruction, bone marrow and disk signal abnormalities, and paravertebral or epidural abscesses. However, it is not always easy to diagnose a spinal infection, particularly when some of the classic MR imaging features are absent or when there are unusual patterns of infectious spondylitis. Furthermore, noninfectious inflammatory diseases and degenerative disease may simulate spinal infection. It is necessary to be familiar with atypical MR imaging findings of spinal infection and features that may mimic spinal infection to avoid misdiagnosis and inappropriate treatment.

MRI Findings of Subcutaneous Epidermal Cysts: Emphasis on the Presence of Rupture

OBJECTIVE Our aim was to describe the MRI findings of subcutaneous epidermal cysts with an emphasis on determining the presence of rupture. CONCLUSION Epidermal cysts show a fluidlike signal with variable low-signal components on T2-weighted images and peripheral rim enhancement on gadolinium-enhanced images. Most ruptured cysts have septa, show thick and irregular rim enhancement, and are accompanied by a fuzzy enhancement in surrounding subcutaneous tissues. These imaging features of a ruptured epidermal cyst simulate a mass of infectious or neoplastic origin.

Grading of anterior cruciate ligament injury: Diagnostic efficacy of oblique coronal magnetic resonance imaging of the knee

Objective This study was undertaken to evaluate the diagnostic efficacy of additional oblique coronal magnetic resonance (MR) imaging of the knee for the grading of anterior cruciate ligament (ACL) injury. Methods We retrospectively reviewed MR images of the knee in 169 patients. The MR examinations included routine sequences and oblique coronal T2-weighted images, which oriented in parallel to the course of the femoral intercondylar roof. Two independent readers evaluated the status of the ACL by routine knee MR imaging and then by additional oblique coronal imaging. The severity of the ACL injury was graded using a 4-point system from MR images, namely, intact, low-grade partial tear, high-grade partial tear, and complete tear, and results were compared with arthroscopic findings. Weighted &kgr; statistics were used to analyze the diagnostic accuracy of routine knee MR imaging with and without additional oblique coronal imaging. Results The weighted &kgr; scores (&kgr;ws) were 0.752 (reader 1) and 0.784 (reader 2) by routine knee MR imaging only; with additional oblique coronal imaging, the &kgr;ws increased to 0.809 (reader 1) and 0.843 (reader 2). Interobserver agreements for routine knee MR imaging and additional coronal imaging were considered to be “very good” (&kgr;w = 0.851, 0.868, respectively). Conclusion Additional use of oblique coronal MR imaging of the knee improves diagnostic accuracy in the grading of ACL injury.

MR Imaging Mapping of Skeletal Muscle Denervation in Entrapment and Compressive Neuropathies

The diagnoses of entrapment and compressive neuropathies have been based on the findings from clinical examinations and electrophysiologic tests, such as electromyography and nerve conduction studies. The use of magnetic resonance (MR) imaging for the diagnosis of entrapment or compressive neuropathies is increasing because MR imaging is particularly useful for discerning potential causes and for identifying associated muscle denervation. However, it is sometimes difficult to localize nerve entrapment or demonstrate nerve compression lesions with MR imaging. Nevertheless, even in these cases, MR imaging may show denervation-associated changes in specific muscles innervated by the affected nerves. The analysis of denervated muscle distributions by using MR imaging, with a knowledge of nerve innervation patterns, would be helpful for determining the nerves involved and the levels of nerve entrapment or compression. In this context, the mapping of skeletal muscle denervation with MR imaging has a supplementary or even a primary role in the diagnosis of entrapment and compressive neuropathies.

New MRI Grading System for the Cervical Canal Stenosis

OBJECTIVE The purpose of this study was to propose a new MRI grading system for cervical canal stenosis and to evaluate the reproducibility of the system. MATERIALS AND METHODS Cervical canal stenosis was classified according to the T2-weighted sagittal images into the following grades: grade 0, absence of canal stenosis; grade 1, subarachnoid space obliteration exceeding 50%; grade 2, spinal cord deformity; and grade 3, spinal cord signal change. The MRI scans of 82 patients (37 men and 45 women; mean age, 65.2 years; range, 60-86 years) were independently analyzed by six radiologists. Interobserver and intraobserver agreements were analyzed using intraclass correlation coefficient (ICC), along with the percentage agreement and kappa statistics. RESULTS The ICC for interobserver agreement was 0.716-0.802, indicating good-to-excellent agreement. For the distinction among the four grades, the percentage of agreement was 63-64% (κ = 0.60-0.62). The percentage of agreement for the presence of cervical canal stenosis (grade 0 vs grades 1, 2, and 3) was 79-85% (κ = 0.51-0.59). The percentage of agreement for insignificant (grade 0-1) or significant (grade 2-3) stenosis was 81-85% (κ = 0.57-0.66). The percentage of agreement for the presence of spinal cord signal change (grade 0-2 vs grade 3) was 92-95% (κ = 0.70-0.73). The overall intraobserver agreement was excellent, as determined by an ICC of 0.768. CONCLUSION The new grading system provides a reliable assessment of cervical canal stenosis.

Acute Appendicitis in Young Adults: Low- versus Standard-Radiation-Dose Contrast-enhanced Abdominal CT for Diagnosis

PURPOSE To compare low and standard radiation doses in intravenous contrast material-enhanced abdominal computed tomography (CT) for the diagnosis of acute appendicitis in young adults. MATERIALS AND METHODS The institutional review board approved this retrospective study and waived informed consent. The study included 257 patients (age range, 15-40 years) who underwent CT for suspected appendicitis performed by using a low radiation dose (n = 125) or a standard radiation dose (n = 132). Receiver operating characteristic (ROC) analysis, Fisher exact tests, and Mann-Whitney U tests were used to compare the diagnosis of appendicitis and diagnostic confidence as recorded in prospective CT reports between the two groups. RESULTS For 55 low-radiation-dose (median dose-length product, 122 mGy · cm) and 44 standard-dose (median dose-length product, 544 mGy · cm) examinations, one of two abdominal radiologists made primary reports that served as final reports. For the remaining examinations, on-call radiologists with differing levels of experience issued preliminary reports and the two abdominal radiologists then provided final reports. In the primary reports, the low- and standard-dose CT groups did not significantly differ in area under the ROC curve (0.96 vs 0.97, P = .76), sensitivity (90% [38 of 42] vs 89% [47 of 53], P > .99), or specificity (92% [76 of 83] vs 94% [74 of 79], P = .74) in the diagnosis of appendicitis. There was also no significant difference between the two groups in the confidence level when diagnosing (P = .71) or excluding (P = .20) appendicitis in the primary reports. Similar results were observed for the final reports. The two dose groups also did not significantly differ in terms of appendiceal visualization, diagnosis of appendiceal perforation, or sensitivity for alternative diagnoses. CONCLUSION Low-dose CT may have comparable diagnostic performance to standard-dose CT for the diagnosis of appendicitis in young adults.

Tuberculosis of the ribs: CT appearance.

Tuberculosis is the most common inflammatory lesion of the ribs, second only to metastatic neoplasm as a destructive cause of a rib lesion. We retrospectively analyzed CT findings of 13 lesions in eight patients with pathologically proven rib tuberculosis. The presenting symptoms were painful mass in five, chest pain in two, and nontender mass in one. Five patients had concomitant pulmonary tuberculosis. On CT, all showed a juxtacostal soft tissue mass with central low attenuation and peripheral rim enhancement (a so called “cold abscess”). Only 4 of 13 lesions demonstrated bone destruction: two were osteolytic expansile lesions with cortical disruption and two were mild cortical irregularities. Five lesions were located at the costochondral junction, five were in the rib shaft, two were in the sternochondral junction, and one was in the costovertebral joint. There was no evidence of direct extension into the lung parenchyma.