Christopher G. Anton

T2 relaxation time changes in distal femoral articular cartilage in children with juvenile idiopathic arthritis: a 3-year longitudinal study.

OBJECTIVE Increased cartilage T2 relaxation time is thought to be an early marker of disease progression in juvenile idiopathic arthritis, because it can identify microstructural changes before damage becomes visible. The purpose of this study was to investigate longitudinal changes in T2 relaxation time mapping (i.e., T2 map) in children with early juvenile idiopathic arthritis and to compare with changes in clinical assessments. SUBJECTS AND METHODS Twenty children (age range, 6.4-16 years) with early juvenile idiopathic arthritis completed at least four evaluations with T2 maps and clinical assessments: at enrollment, at 3 months, and at 1, 2, and 3 years. Sagittal T2 maps of distal femoral cartilage were generated, a region of interest was selected, and a T2 relaxation time profile was generated. The area under the curve from the T2 profile (i.e., T2 value) was correlated with patient age and sex and the following clinical assessments: total knee score, Childhood Health Assessment Questionnaire, physician global assessment, parent global assessment, and total number of active joints. RESULTS There was a significant increase in mean T2 values from 3 months to 2 years (p < 0.05). There was a significant decrease in mean Childhood Health Assessment Questionnaire values between enrollment and 2 years (p < 0.05) and a significant decrease in parent global assessment, physician global assessment, total number of active joints, and total knee score values between enrollment and 1 year (p < 0.05). There were no statistically significant correlations between T2 values and patient age, sex, or clinical assessments. CONCLUSION In patients with early juvenile idiopathic arthritis, T2 maps showed increased T2 values from the 3-month to 2-year follow-up, during which time the clinical assessments improved. This increase likely represents progressive microstructural changes, even though clinical symptoms improved with treatment.

Age and sex dependency of cartilage T2 relaxation time mapping in MRI of children and adolescents.

OBJECTIVE T2 relaxation times on MRI are sensitive to the configuration of cartilage collagen and continually increase during aging in adults. In children, T2 relaxation times increase as a result of cartilage microstructure changes in early inflammatory arthritis. The purpose of this study was to determine age- and sex-related differences in T2 mapping of the patellar cartilage in children and adolescents during normal skeletal maturation. MATERIALS AND METHODS Ninety-seven subjects (age range, 5-22 years; 51 females and 46 males; mean age, 14.3 and 13.7 years, respectively) without patellofemoral instability or inflammatory arthritis were included. All subjects underwent 1.5-T knee MRI with T2 mapping. The mean T2 relaxation time and thickness of the patellar cartilage were documented for each MRI examination. Skeletal maturation was determined by physeal patency (open; or closed or closing) on MRI. The associations between T2 relaxation times, cartilage thickness, sex, age, and physeal patency were assessed using Wilcoxon rank sum test and least-squares means regression models. RESULTS T2 relaxation times and thickness of the patellar cartilage significantly decreased (p<0.0001) with increasing chronologic age. T2 relaxation times and cartilage thickness in the open physis group were found to be greater than in the closed or closing physis group (p<0.0001). T2 relaxation times and cartilage thickness were greater in males than in females (p<0.05). CONCLUSION In contrast to senescent changes in adults, skeletal maturation in children results in a sequential decrease in T2 relaxation times that are age- and sex-dependent. Similar to cartilage in adults, cartilage in children gets progressively thinner during skeletal maturation.

Spondylolysis and Beyond: Value of SPECT/CT in Evaluation of Low Back Pain in Children and Young Adults

Single photon emission computed tomography (SPECT)/computed tomography (CT) is ideally suited for assessment of low back pain in children and young adults. Spondylolysis is one of the most common structural causes of low back pain and is readily identified and characterized in terms of its chronicity and likelihood to heal. The value of SPECT/CT extends to identification and characterization of other causes of low back pain, including abnormalities of the posterior elements, developing vertebral endplate, transverse processes, and sacrum and sacroiliac joint. Some of the disease processes that are identifiable at SPECT/CT are similar to those that occur in adults (eg, facet hypertrophy) but may be accelerated in young patients by high-level athletic activities. Other processes (eg, limbus vertebrae) are more unique to children, related to injury of the developing spine. The authors review the spectrum of pars interarticularis abnormalities with emphasis on the imaging features of causes of pediatric low back pain other than spondylolysis.

The intrarater and interrater reliability of glenoid version and glenohumeral subluxation measurements in neonatal brachial plexus palsy.

Background: Progressive and disabling glenohumeral dysplasia commonly occurs as a secondary deformity in children with neonatal brachial plexus palsy (NBPP). A number of methods for quantifying glenohumeral dysplasia are currently in use; however, the most commonly reported quantitative measures have yet to be validated. The present study assesses the intrarater and interrater reliability of the glenoid version angle (GVA) and percent of the humeral head anterior to the scapular line (PHHA) measurements on axial magnetic resonance images. Methods: Axial magnetic resonance images of the shoulder girdle of 25 children with NBPP were selected to represent a wide range of glenohumeral dysplasia severity. An axial image was preselected for each measurement. Six examiners (3 orthopaedic surgeons, 2 musculoskeletal radiologists, and an epidemiologist) digitally measured the GVA and PHHA on each image twice, with each measurement separated by 2 to 14 days and the order of image presentation placed in a different arrangement for each measurement set. Intrarater and interrater reliability was assessed with the intraclass correlation coefficient (ICC). Measurement errors for the GVA and PHHA measurements and the variances associated with the scapular and glenoid lines were calculated. Results: Using the Fleiss criteria, intrarater reliability was excellent, with ICCs averaging 0.909 (95% CI: 0.840, 0.940) for GVA and 0.891 (95% CI: 0.815, 0.921) for PHHA. Interrater reliability was excellent, with ICCs of 0.848 (95% CI: 0.788, 0.909) for GVA and 0.874 (95% CI: 0.815, 0.934) for PHHA. The GVA and PHHA measurement errors were ±6.4 degrees and ±7.2%, respectively. In a subset of 141 images measured, the between-image variance in the scapular line was greater than the glenoid line by a 1.61:1 ratio. Conclusions: The present study demonstrates excellent intrarater and interrater reliability of standard measurements of glenohumeral dysplasia in NBPP. The measurement errors for both measurements were comparable with other standard measures (eg, Cobb angle). The scapular line exhibited a greater variance than the glenoid line, which identifies an opportunity for improvement in the GVA measurement. Level of Evidence: Diagnostic study; level III.

Tailgut cyst in a child

Tailgut cyst, or retrorectal cystic hamartoma, is a rare congenital lesion found in the presacral space. The lesion has been infrequently reported in the literature. We report the MRI findings of a tailgut cyst in a 2-year-old girl who presented with a sacral dimple and skin discoloration.

Spatial Variation of T2 Relaxation Times of Patellar Cartilage and Physeal Patency: An In Vivo Study in Children and Young Adults

OBJECTIVE The purpose of this study was to determine whether the T2 spatial variation of patellar cartilage is different between children and young adults with open and closed physes. MATERIALS AND METHODS Fifty-two subjects in two age ranges were included; 13 girls and 13 boys from 5 to 11 years old, and 13 female young adults and 13 male young adults from 17 to 22 years old. T2 maps of patellar cartilage were generated at 1.5 T. Physeal patency and mean T2 relaxation times as a function of normalized distance (T2 spatial variation) were evaluated in each group and sex. RESULTS All the subjects from 5 to 11 years old had open physes and all the subjects from 17 to 22 years old had closed physes. Mean T2 relaxation times of patellar cartilage in the open physis group were significantly longer than in the closed physis group throughout all normalized distances across patellar cartilage (p<0.05). There were significant differences in T2 spatial variation between the two groups (p<0.05). The open physis group had longer mean T2 relaxation times at the osteochondral area and articular cartilage than in the central portion. The closed physis group had shorter mean T2 relaxation times in the osteochondral area, with a gradual increase to longer values at the articular surface. Differences in T2 spatial variation were greatest at the osteochondral junction (p<0.05). There was no statistically significant sex difference in T2 spatial variation in either group. CONCLUSION T2 spatial variation is different between skeletally immature and mature patellar cartilage. This difference is most prominent at the osteochondral junction and likely relates to the presence or absence of ongoing endochondral ossification.

Little League shoulder: a growth plate injury

A 13-year-old boy, a baseball pitcher, presented with right shoulder pain while throwing. The external oblique image shows widening, irregularity and fragmentation of the proximal humeral physis (Fig. 1). Figure 2 is a comparison radiograph of the asymptomatic left shoulder. Little League shoulder was first described by Dotter [1] in 1953. This injury is commonly known as proximal humeral epiphysiolysis, a confusing term, because Little League shoulder is likely an overuse or stress injury of the proximal humeral growth plate or the adjacent metaphysis rather than

Patellofemoral Instability in Children: Correlation Between Risk Factors, Injury Patterns, and Severity of Cartilage Damage

OBJECTIVE The purpose of this study was to compare MRI findings between groups with and without patellofemoral instability and to correlate the MRI findings with the severity of patellar cartilage damage. MATERIALS AND METHODS Fifty-three children with patellofemoral instability and 53 age- and sex-matched children without patellofemoral instability (15.9 ± 2.4 years) were included. Knee MRI with T2-weighted mapping was performed. On MR images, femoral trochlear dysplasia, patellofemoral malalignment, medial retinaculum injury, and bone marrow edema were documented. The degree of patellar cartilage damage was evaluated on MR images by use of a morphologic grading scale (0-4) and on T2 maps with mean T2 values at the medial, central, and lateral facets. MRI findings were compared between the two groups. In cases of patellofemoral instability, MRI findings were correlated with the severity of cartilage damage at each region. RESULTS Trochlear structure and alignment were significantly different between the two groups (Wilcoxon p < 0.0001). In patellofemoral instability, a high-riding patella was associated with central patellar cartilage damage with a higher morphologic grade and T2 value (Spearman p < 0.05). The severity of medial retinacular injury and presence of bone marrow edema at either the medial patella or the lateral femoral condyle were associated with a higher grade of medial patellar cartilage damage (Wilcoxon p < 0.05). None of the other findings correlated with the severity of patellar cartilage damage. CONCLUSION Patients with patellofemoral instability have significantly different trochlear structure and alignment than those who do not, and these differences are known risk factors for patellofemoral instability. However, the only risk factors or injury patterns that directly correlated with the severity of patellar cartilage damage were patella alta, medial stabilizer injury, and bone marrow edema.

CT evaluation of extensor tendon entrapment as a complication of a distal radial fracture in a child

Extensor indicis proprius (EIP) entrapment is a rare complication of a distal radial fracture. We report an 11-year-old with limited flexion of her index finger 1 year after a distal radial fracture. The utility of cross-sectional imaging in the diagnosis and preoperative planning of this complication is presented.