Specialist learning curves and clinical feasibility of introducing a new MRI grading system for skeletal maturity.

Objective: MRI is an emerging imaging modality to assess skeletal maturity. This study aimed to chart the learning curves of paediatric radiologists when using an unfamiliar MRI grading system of skeletal maturity and to assess the clinical feasibility of implementing said system. Methods: 958 healthy paediatric volunteers were prospectively included in a dual-facility study. Each subject underwent a conventional MRI scan at 1.5 T. To perform the image reading, the participants were grouped into five subsets (subsets 1-5) of equal size (n∼192) in chronological order for scan acquisition. Two paediatric radiologists (R1-2) with different levels of MRI experience, both of whom were previously unfamiliar with the study's MRI grading system, independently evaluated the subsets to assess skeletal maturity in five different growth plate locations. Congruent cases at blinded reading established the consensus reading. For discrepant cases, the consensus reading was obtained through an unblinded reading by a third paediatric radiologist (R3), also unfamiliar with the MRI grading system. Further, R1 performed a second blinded image reading for all included subjects with a memory wash-out of 180 days. Weighted Cohen kappa was used to assess interreader reliability (R1 vs consensus; R2 vs consensus) at non-cumulative and cumulative time points, as well as interreader (R1 vs R2) and intrareader (R1 vs R1) reliability at non-cumulative time points. Results: Mean weighted Cohen kappa values for each pair of blinded readers compared to consensus reading (interreader reliability, R1-2 vs consensus) were ≥0.85, showing a strong to almost perfect interreader agreement at both non-cumulative and cumulative time points and in all growth plate locations. Weighted Cohen kappa values for interreader (R1 vs R2) and intrareader reliability (R1 vs R1) were ≥0.72 at non-cumulative time points, with values ≥0.82 at subset 5. Conclusions: Paediatric radiologists' clinical confidence when introduced to a new MRI grading system for skeletal maturity was high from the outset of their learning curve, despite the radiologists' varying levels of work experience with MRI assessment. The MRI grading system for skeletal maturity investigated in this study is a robust clinical method when used by paediatric radiologists and can be used in clinical practice. Advances in knowledge: Radiologists with fellowship training in paediatric radiology experienced no learning curve progress when introduced to a new MRI grading system for skeletal maturity and achieved desirable agreement from the first time point of the learning curve. The robustness of the investigated MRI grading system was not affected by the earlier different levels of MRI experience among the readers.

Anatomical and dynamic rotational alignment in spastic unilateral cerebral palsy.

BACKGROUND: Even in mild unilateral cerebral palsy increased internal hip rotation can be noted on physical- and gait examination. The influence of spasticity on femoral growth in the transverse plane is not clear. These deviations and asymmetry in movement pattern may negatively affect efficiency of gait and cause psychological concerns about appearance. RESEARCH QUESTION: Is increased internal hip rotation on the involved side in mild unilateral CP common and is there compensatory external pelvic rotation to keep foot progression symmetrical? METHODS: This prospective study included 45 individuals with unilateral cerebral palsy, mean age 17.7 (13.0-24.0) years. All were Gross Motor Function Classification Level I. Physical examination, three-dimensional gait analysis and magnetic resonance imaging for assessment of rotational alignment was performed. RESULTS: On physical examination internal hip rotation was mean 50.6 (SD 10.4) degrees on the involved side and 44.3 (SD 10.3) on the non-involved side, p = 0.001. In gait analysis calculating the whole gait cycle, internal hip rotation was mean 2.3 (6.2) degrees on the involved side, and on the non-involved side external 1.8 (7.6) degrees, p = 0.004. Increased external pelvic rotation was noted on the involved side, mean 2.0 (4.3) degrees with corresponding internal rotation on the non-involved side, mean 3.6 (4.4), p = 0.001. There was no difference in foot progression, p = 0.067, with mean 5.1 (8.6) and 3.9 (6.4) external respectively. Magnetic resonance imaging revealed femoral torsion on the involved side mean 17.3 (11.3) degrees compared to 11.4 (10.8) on the non-involved side, p = 0.001. SIGNIFICANCE: Transverse plane asymmetry in the femur was noted in mild unilateral cerebral palsy. Increased anatomical and dynamic internal rotation was compensated for by external pelvic rotation. Rotational malalignment may contribute to gait deviations in this mild group and should be part of the overall assessment.

T2 mapping and post-contrast T1 (dGEMRIC) of the patellar cartilage: 12-year follow-up after patellar stabilizing surgery in childhood.

BACKGROUND: Cartilage degeneration has been reported after recurrent patellar dislocation. However, effects of surgical stabilization in childhood have not yet been described. PURPOSE: To examine the cartilage quality in very young adults operated with a patellar stabilizing procedure due to recurrent patellar dislocation in childhood, and evaluate if cartilage quality correlates with clinical parameters and patient-reported outcomes. MATERIAL AND METHODS: Seventeen patients were investigated ≥ 5 years (mean = 11.6 years) after patellar stabilizing surgery in childhood. Pre-contrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after 0.2 mM/kg Gd-DTPA2 i.v., post-contrast T1 (T1(Gd)) was analyzed in the same regions. Patient-reported outcomes (KOOS, Kujala, and Tegner scores) and recurrence rates were evaluated. RESULTS: Comparing operated to healthy side, neither T2 nor dGEMRIC differed between the operated and the reference knee regarding the superficial half of the cartilage. In the deep half of the cartilage, T1(Gd) was shorter in the central part of the cartilage, whereas T2 was longer medially (P < 0.05). A low score in the KOOS subscales Symptom and Sports & Recreation, was correlated to the degenerative changes detected by T1(Gd) (r = 0.5, P = 0.041). CONCLUSION: In general, our findings demonstrate good cartilage quality 12 years after patellar stabilizing surgery during childhood. The subtle changes in T2 and T1(Gd) in the deep cartilage layer may be a result of altered biomechanics, although very early degenerative changes cannot be excluded. The short T1(Gd) centrally may reflect lower glycosaminoglycan content, whereas the increase in T2 medially indicates increased cartilage hydration.

Morphology and Anatomic Patellar Instability Risk Factors in First-Time Traumatic Lateral Patellar Dislocations: A Prospective Magnetic Resonance Imaging Study in Skeletally Immature Children.

BACKGROUND: The incidence of primary lateral patellar dislocation (LPD) in children aged 9 to 14 years is 0.6 to 1.2 per 1000. Causation is assumed to be multifactorial, including anatomic variants of the patellofemoral (PF) joint that result in a higher risk of LPD. No publication has compared the morphology of the PF joint and anatomic patellar instability risk factors (APIFs) in a primary LPD population versus controls, defining children by skeletal maturity. PURPOSE: To characterize the PF morphology and APIFs (trochlear dysplasia, abnormal lateral patellar tilt, elevated tibial tubercle-trochlear groove [TT-TG] distance, patella alta) through magnetic resonance imaging (MRI) measurements in skeletally immature children with and without a primary LPD and to identify (potential) distinctive differences between these 2 groups. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A prospective series of 103 skeletally immature children aged 9 to 14 years with an MRI-confirmed primary LPD were matched with a control group of 69 children. The PF morphology and APIFs were assessed during a 2.5-year period with standardized MRI using sagittal and axial views. RESULTS: In the LPD group, 79% had 2 to 4 APIFs compared with 7% in the control group. All major measurements of trochlear dysplasia were significantly different between the 2 groups. The mean central condylar height was significantly higher in the LPD group compared with the control group, resulting in a lower trochlear depth (2.3 vs 4.5 mm, respectively) and higher sulcus angle (156.7° vs 141.1°, respectively). The LPD group had significantly higher values of patellar height, Caton-Deschamps index (1.33 vs 1.15, respectively), lateral patellar tilt (21.1° vs 8.5°, respectively), and TT-TG distance (13.9 vs 9.8 mm, respectively) compared with the control group. The main divergent APIF was trochlear dysplasia (defined as trochlear depth <3 mm), seen in 74% of the LPD group compared with 4% of the control group. Elevated TT-TG distance as a single APIF was never present in the LPD group; patellar tilt was only seen in the LPD group. The most common APIF in the control group was patella alta (36%). CONCLUSION: There was a significant difference in mean values of all established APIFs between the children with a first-time LPD and the controls. Trochlear dysplasia was the main APIF, and together with lateral patellar tilt (≥20°), they had the strongest association with LPD.

Medial Patellofemoral Ligament Injuries in Children With First-Time Lateral Patellar Dislocations: A Magnetic Resonance Imaging and Arthroscopic Study.

BACKGROUND: A lateral patellar dislocation (LPD) is the most common knee injury in children with traumatic knee hemarthrosis. The medial patellofemoral ligament (MPFL), the important passive stabilizer against LPDs, is injured in more than 90% of cases. The MPFL injury pattern is most often defined in adults or in mixed-age populations. The injury pattern in the skeletally immature patient may be different. PURPOSE: To describe MPFL injuries in the skeletally immature patient by magnetic resonance imaging (MRI), and to compare the results with the injury pattern found at arthroscopic surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This was a prospective series of patients aged 9 to 14 years with acute, first-time traumatic LPDs in whom clinical examinations, radiographs, MRI, and arthroscopic surgery were performed within 2 weeks from the index injury. The MPFL injury was divided into 3 different groups according to the location: patellar site, femoral site, or multifocal. The MPFL injury site was confirmed on MRI by soft tissue edema. The length of the MPFL injury at the patellar site was measured at arthroscopic surgery, and those ≥2 cm were defined as total ruptures. RESULTS: A total of 74 patients (40 girls and 34 boys; mean age, 13.1 years) were included; 73 patients (99%) had an MPFL injury according to MRI and arthroscopic surgery. The MRI scans showed an isolated MPFL injury at the patellar attachment site in 44 of 74 patients (60%), a multifocal injury in 26 patients (35%), an injury at the femoral site in 3 patients (4%), and no injury in 1 patient (1%). Arthroscopic surgery disclosed an isolated MPFL injury at the patellar site in 60 of 74 patients (81%) and a multifocal injury in 13 patients (18%); the MPFL injury at the patellar site was a total rupture in 49 patients (66%). Edema at the patellar attachment site on MRI was proven to be an MPFL rupture at the same site at arthroscopic surgery in 99% of the patients. A patellar-based injury, isolated or as part of a multifocal injury, was present on MRI in 95% (n = 70) of the patients, with a false-negative rate of 5% (n = 4) of patients compared with arthroscopic surgery. CONCLUSION: Skeletally immature children are more prone to sustaining an MPFL injury at the patellar attachment site. Arthroscopic surgery and MRI complement each other in the investigation of MPFL injuries.

Pre- and postcontrast T1 and T2 mapping of patellar cartilage in young adults with recurrent patellar dislocation.

PURPOSE: To examine the cartilage quality in young adults with recurrent patellar dislocation in childhood using different magnetic resonance imaging parameters. METHODS: Sixteen young adults with unilateral recurrent patellar dislocation were investigated ≥5 y (mean, 8.5 y) after the first dislocation. Pre- and postcontrast T1 and precontrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after intravenous injection of 0.2 mM/kg Gd-DTPA(2-), postcontrast T1 [T1(Gd)] and ΔR1 [1/T1 (precontrast) - 1/T1 (postcontrast)] were analyzed in the regions. Muscle performance and patient-reported outcome were evaluated. RESULTS: When comparing the injured side with the noninjured side, differences were seen in the superficial half but not the deep half of the cartilage. T1(Gd) was shorter in the central part, whereas T2 was shorter in the periphery of the patellar cartilage (P < 0.05). ΔR1 demonstrated similar differences between healthy and diseased cartilage as T1(Gd) alone. The knee function was not correlated to the degenerative changes. CONCLUSION: The short T1(Gd) centrally indicates degenerative cartilage changes consistent with loss of glycosaminoglycans. Precontrast and ΔR1 calculations may be excluded in clinical dGEMRIC, which simplifies the procedure. A decrease in T2 may be a very early sign of joint pathology but warrants further investigation.

Occult Intra-articular Knee Injuries in Children With Hemarthrosis.

BACKGROUND: Hemarthrosis after acute knee trauma is a sign of a potentially serious knee injury. Few studies have described the epidemiology and detailed injury spectrum of acute knee injuries in a general pediatric population. PURPOSE: To document the current injury spectrum of acute knee injuries with hemarthrosis in children aged 9 to 14 years and to describe the distribution of sex, age at injury, type of activity, and activity frequency in this population. STUDY DESIGN: Descriptive epidemiology study. METHODS: All patients in the Stockholm County area aged 9 to 14 years who suffered acute knee trauma with hemarthrosis were referred to Astrid Lindgren Children's Hospital, Karolinska University Hospital, from September 2011 to April 2012. The patients underwent clinical examination, radiography, and magnetic resonance imaging (MRI). The type of activity when injured, regular sports activity/frequency, and patient sex and age were registered. The diagnoses were classified into minor and serious injuries. RESULTS: The study included 117 patients (47 girls and 70 boys; mean age, 13.2 years). Seventy percent had a serious knee injury. Lateral patellar dislocations, anterior cruciate ligament ruptures, and anterior tibial spine fractures were the most common injuries, with an incidence of 0.6, 0.2, and 0.1 per 1000 children, respectively. The sex distribution was equal up to age 13 years; twice as many boys were seen at the age of 14 years. The majority of injuries occurred during sports. Forty-six patients (39%) had radiographs without a bony injury but with a serious injury confirmed on MRI. CONCLUSION: Seventy percent of the patients aged 9 to 14 years with traumatic knee hemarthrosis had a serious intra-articular injury that needed specific medical attention. Fifty-six percent of these patients had no visible injury on plain radiographs. Physicians who treat this group of patients should consider MRI to establish the diagnosis when there is no or minimal radiographic findings. The most common serious knee injury was a lateral patellar dislocation. This should be taken into consideration to improve prevention strategies and treatment algorithms in pediatric knee injuries.

Leg length discrepancy in spastic hemiplegic cerebral palsy: a magnetic resonance imaging study.

BACKGROUND: In patients with spastic hemiplegic cerebral palsy (CP) it can be difficult to clearly define whether deviations in gait pattern result from impaired motor control, leg length discrepancy (LLD), or are a consequence of secondary compensatory mechanisms. LLD is common and treatment can be considered. The goal was to investigate the degree of LLD in the lower limb including the pelvis, femur, tibia, talus, and calcaneus using magnetic resonance imaging (MRI). METHODS: Forty-four patients with spastic hemiplegic CP and a mean age of 17.6 years (range, 13.0 to 23.0 y) participated in the study; of these 20 were female and 24 were male. All were classified as 1 on the gross motor classification scale and as Winters' type 1 or 2. On the basis of sagittal T1-weighted MRI images of the lower extremity, the length of the pelvis, femur, tibia, talus, and calcaneus was measured separately by 2 experienced observers and remeasured independently after a 2-week interval. RESULTS: Eleven of the 44 patients had a hemiplegic lower limb that was more than 15 mm shorter. The mean difference was in the calcaneus (0.9 mm; P=0.003), talus (1.3 mm; P=0.006), and tibia (8.1 mm; P=0.000). Intraobserver comparison showed high reproducibility with intraclass correlation for the calcaneus (0.91), talus (0.84), tibia (0.99), femur (0.99), and pelvis (0.98). In the interobserver comparison, the corresponding inter class correlations were 0.95, 0.84, 0.99, 0.99, and 0.98. CONCLUSIONS: This MRI study showed LLD in teenagers and young adults with hemiplegic CP. The main difference between the hemiplegic and noninvolved side was found in the tibia, but the calcaneus and talus also showed significant differences. The method proved to be reliable and the measurement of LLD should be considered in the management of hemiplegic CP. To be able to develop rational treatment plans, it is of importance to know the degree and location of LLD. LEVEL OF EVIDENCE: Prospective cross-sectional diagnostic level 1 study.

Suspected appendicitis in children: diagnosis with contrast-enhanced versus nonenhanced Helical CT.

PURPOSE: To compare the diagnostic accuracy of limited-area (lower abdominal) nonenhanced helical computed tomography (CT), intravenous contrast material-enhanced helical CT of the entire abdomen, and the combination of both. MATERIALS AND METHODS: Three hundred six children suspected of having appendicitis, who were previously included in a prospective study, underwent limited-area nonenhanced helical CT of the lower abdomen and contrast-enhanced CT of the entire abdomen. No oral or rectal contrast material was administered. The CT scans were retrospectively reviewed by three independent readers both separately and together. The readers were blinded to all clinical information and to the results of previous ultrasonographic and CT examinations. Final diagnoses were established on the basis of surgical, histopathologic, or clinical follow-up findings. The Pearson chi(2) test was performed to compare values between groups. The Student two-sample t test was performed to determine statistically significant differences in age and sex. RESULTS: One hundred twenty-nine patients (42%) had appendicitis. Readers diagnosed appendicitis with 66% pooled sensitivity and 96% pooled specificity with limited-area nonenhanced CT. With contrast-enhanced CT of the entire abdomen, appendicitis was diagnosed with 90% pooled sensitivity and 94% pooled specificity. With both sequences together, readers diagnosed appendicitis with 90% pooled sensitivity and 94% pooled specificity. The difference between the sensitivity of limited-area nonenhanced CT and that of contrast-enhanced CT was statistically significant (P <.001). CONCLUSION: Sensitivity of helical CT for suspected appendicitis in children improved significantly with abdominal contrast-enhanced CT compared with limited-area nonenhanced CT. No further improvement in sensitivity was achieved with the combination of both sequences in comparison to that with contrast-enhanced CT alone.

Side markings of the neonatal chest X-ray: two legal cases of pneumothorax side mix up.

Two medicolegal case reports are presented. They involve chest X-ray with left-and-right side confusion due to lack of radio-opaque side markers. Two premature babies with pneumothorax got thoracostomy on the wrong side, in one case with a fatal outcome.