Feasibility of Magnetic Resonance Angiography in Patients With Legg-Calvé-Perthes Disease.

BACKGROUND: The etiology of Legg-Calvé-Perthes disease (LCPD) remains unknown; however, interruption of medial circumflex femoral artery (MCFA) supply to the femoral head is the key pathogenic factor. The main purpose of this study is to determine the feasibility of using magnetic resonance angiography (MRA) to evaluate the course of the MCFA in the normal and affected hips of patients with unilateral LCPD. METHODS: We analyzed 24 patients with unilateral LCPD using a time-resolved imaging of contrast kinetics magnetic resonance angiography (TRICKS-MRA). The course of the MCFA was divided into 4 segments in the coronal plane and in 3 segments in the axial plane, based on its location with respect to the femoral neck. The visibility of each segment was studied in the normal and affected sides. The segments were defined as not visible when no contrast was seen within the vessel lumen or visible when the lumen was partially or completely visualized with contrast. The statistical analysis was done using the χ2 test. RESULTS: TRICKS-MRA provided well-defined images of the first 2 segments of the MCFA on both the normal and affected sides of patients with LCPD (P=1). In half of the patients, the third segment was also visible using TRICKS-MRA on both sides (P=1). The fourth segment of the MCFA, which was the ascending lateral epiphyseal segment, was not visible on either side (P=0.49). No significant difference was found between the normal and affected hips in terms of visibility of the 4 segments of the MCFA using TRICKS-MRA. Anastomosis of the MCFA with the inferior gluteal artery was found in 3 hips (2 hips with LCPD and 1 normal hip). CONCLUSIONS: TRICKS-MRA provides well-defined images of the arterial supply to the proximal femoral epiphysis in children with LCPD, presenting a noninvasive and radiation-free alternative to conventional angiography. However, the TRICKS-MRA method used did not allow visualization of the ascending lateral epiphyseal segment of MCFA in the affected and the contralateral normal side. We believe that further advancement of this noninvasive imaging technique may open new opportunities for research aimed at evaluating the vascular supply of the femoral head in children. LEVEL OF EVIDENCE: Level IV-case-control study.

Fast field echo resembling a CT using restricted echo-spacing (FRACTURE): a novel MRI technique with superior bone contrast.

OBJECTIVE: Computerized tomography (CT) is the modality of choice for imaging bone; however, it utilizes ionizing radiation and suffers from poor soft-tissue contrast. Unlike CT, magnetic resonance imaging (MRI) provides excellent soft-tissue contrast but is limited in its ability to image bone. The objective of this study is to describe a new technical innovation which provides superior cortical and trabecular bone contrast on MRI. METHODS: FRACTURE (fast field echo resembling a CT using restricted echo-spacing), a 3D gradient echo pulse sequence with restricted echo-spacing combined with an automated post-processing, is described. RESULTS: Cases demonstrating the application and utility of this technique in diagnostic MRI performed for traumatic, inflammatory, neoplastic, and developmental conditions in pediatric patients are presented. CONCLUSION: The cortical and trabecular bone contrast generated by FRACTURE yields clinically relevant information for diagnosis and management of a subset of patients in whom it may potentially obviate the need for a preoperative CT scan.

ACR Appropriateness Criteria® Suspected Physical Abuse-Child.

The youngest children, particularly in the first year of life, are the most vulnerable to physical abuse. Skeletal survey is the universal screening examination in children 24 months of age and younger. Fractures occur in over half of abused children. Rib fractures may be the only abnormality in about 30%. A repeat limited skeletal survey after 2 weeks can detect additional fractures and can provide fracture dating information. The type and extent of additional imaging for pediatric patients being evaluated for suspected physical abuse depends on the age of the child, the presence of neurologic signs and symptoms, evidence of thoracic or abdominopelvic injuries, and social considerations. Unenhanced CT of the head is the initial study for suspected intracranial injury. Clinically occult abusive head trauma can occur, especially in young infants. Therefore, head CT should be performed in selected neurologically asymptomatic physical abuse patients. Contrast-enhanced CT of the abdomen/pelvis is utilized for suspected intra-abdominal or pelvic injury. Particular attention should be paid to discrepancies between the patterns of injury and the reported clinical history. Making the diagnosis of child abuse also requires differentiation from anatomical and developmental variants and possible underlying metabolic and genetic conditions. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Urinary Tract Infection-Child.

Urinary tract infection (UTI) is common in young children and may cause pyelonephritis and renal scarring. Long-term complications from renal scarring are low. The role of imaging is to evaluate for underlying urologic abnormalities and guide treatment. In neonates there is increased risk for underlying urologic abnormalities. Evaluation for vesicoureteral reflux (VUR) may be appropriate especially in boys because of higher prevalence of VUR and to exclude posterior urethral valve. In children older than 2 months with first episode of uncomplicated UTI, there is no clear benefit of prophylactic antibiotic. Ultrasound is the only study that is usually appropriate. After the age of 6 years, UTIs are infrequent. There is no need for routine imaging as VUR is less common. In children with recurrent or complicated UTI, in addition to ultrasound, imaging of VUR is usually appropriate. Renal cortical scintigraphy may be appropriate in children with VUR, as renal scarring may support surgical intervention. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

3D MRI Quantification of Femoral Head Deformity in Legg-Calvé-Perthes Disease.

The purpose of this study was to quantify femoral head deformity in patients with Legg-Calvé-Perthes disease (LCPD) using a novel three dimensional (3D) magnetic resonance imaging (MRI) reconstruction and volume based analysis. Bilateral femoral heads of 17 patients (mean age 9.9 ± 2.0 years; 12 boys, 5 girls) with LCPD were scanned 1-2 times (n = 33 LCPD heads, 20 normal heads) using a 1.5T MRI scanner. Fourteen patients had unilateral and three had bilateral LCPD with five hips in the Waldenström initial stage, 9 in the fragmentation stage, 14 in the reossification stage, and 5 in the healed stage. 3D digital reconstructions of femoral heads were created using MIMICS software. Deformity was quantified using a 3D volume ratio method based on reference hemisphere volume as well as two surface geometry methods. Intra-observer analysis showed that 97% of the LCPD femoral heads were within 10% of the original value and test shapes had 99.6% accuracy. For normal femoral heads, the volume ratios of all except one were between 95 and 98% (n = 20) of a perfect hemisphere volume. For femoral heads affected with LCPD, the volume ratios ranged from 43% to 96% of a perfect hemisphere (n = 33). The volume ratio method and the two surface geometry comparison methods had high correlation (r = 0.89 and 0.96). In summary, the 3D MRI volume ratio method allowed accurate quantification and demonstrated small changes (<10%) of the femoral head deformity in LCPD. This method may serve as a useful tool to evaluate the effects of treatment on femoral head shape. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2051-2058, 2017.

Assessment of Femoral Head Revascularization in Legg-Calvé-Perthes Disease Using Serial Perfusion MRI.

BACKGROUND: Legg-Calvé-Perthes disease is a juvenile form of osteonecrosis of the femoral head. The purpose of this study was to use serial perfusion magnetic resonance imaging (MRI) to determine the pattern and rate of revascularization of the femoral heads of patients with the active stage of Legg-Calvé-Perthes disease. METHODS: We performed a prospective study of 29 patients (30 hips) with a mean age (and standard deviation) of 8.4 ± 1.9 years who were diagnosed with Waldenström Stage-1 or 2 Legg-Calvé-Perthes disease. All patients had ≥2 perfusion MRIs, and 21 patients (22 hips) had ≥3. Perfusion percentages of the femoral epiphyses were measured by 2 independent observers. Statistical analyses included calculation of the intraclass correlation coefficient, the paired t test, the Mann-Whitney U test, and the Kruskal-Wallis test. RESULTS: Initial perfusion MRIs showed the percent perfusion in the affected femoral heads to range from 5% to 70%. The average percent perfusion (and standard deviation) was 35% ± 16% on the first MRI, which increased to 77% ± 14% on the follow-up MRI acquired at an average of 10.5 ± 2.9 months later (p < 0.01). Serial assessment showed a general pattern of revascularization starting from the periphery of the posterior, lateral, and medial aspects of the femoral epiphysis and converging toward the anterocentral region. The average rate of revascularization was 4.9% ± 2.3% per month with a wide range among the patients (0.6% to 10.4% per month). CONCLUSIONS: Revascularization of the necrotic femoral head increased over time in a horseshoe pattern, starting from the posterior, lateral, and medial aspects of the femoral epiphysis. The rate of revascularization was highly variable among patients. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

ACR Appropriateness Criteria Fever Without Source or Unknown Origin-Child.

The cause of fever in a child can often be determined from history, physical examination, and laboratory tests; infections account for the majority of cases. Yet in 20%, no apparent cause can be found, designated as fever without source (FWS). The yield of chest radiography in children with FWS is low, and it is usually not appropriate. However, in children with respiratory signs, high fever (>39°C), or marked leukocytosis (≥20,000/mm(3)), chest radiography is usually appropriate, as it has a higher yield in detecting clinically occult pneumonia. In newborns with FWS, there is higher risk for serious bacterial infection, and the routine use of chest radiography is controversial. In children with neutropenia, fever is a major concern. In some clinical circumstances, such as after hematopoietic stem cell transplantation, chest CT scan may be appropriate even if the results of chest radiography are negative or nonspecific, as it has higher sensitivity and can demonstrate specific findings (such as lung nodule and "halo sign") that can guide management. In a child with prolonged fever of unknown origin despite extensive medical workup (fever of unknown origin), diagnosis is usually dependent on clinical and laboratory studies, and imaging tests have low yield. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria Osteonecrosis of the Hip.

Osteonecrosis of the hip (Legg-Calvé-Perthes) is a common disease, with 10,000-20,000 symptomatic cases annually in the United States. The disorder affects both adults and children and is most frequently associated with trauma and corticosteroid usage. The initial imaging evaluation of suspected hip osteonecrosis is done using radiography. MRI is the most sensitive and specific imaging modality for diagnosis of osteonecrosis of the hip. The clinical significance of hip osteonecrosis is dependent on its potential for articular collapse. The likelihood of articular collapse is significantly increased with involvement of greater than 30%-50% of the femoral head area, which is optimally evaluated by MRI, often in the sagittal plane. Contrast-enhanced MRI may be needed to detect early osteonecrosis of the hip in pediatric patients, revealing hypoperfusion. In patients with a contraindication for MRI, use of either CT or bone scintigraphy with SPECT (single-photon emission CT) are alternative radiologic methods of assessment. Imaging helps guide treatment, which may include core decompression, osteotomy, and ultimately, need for joint replacement. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria Acute Trauma to the Knee.

More than 500,000 visits to the emergency room occur annually in the United States, for acute knee trauma. Many of these are twisting injuries in young patients who can walk and bear weight, and emergent radiographs are not required. Several clinical decision rules have been devised that can considerably reduce the number of radiographs ordered without missing a clinically significant fracture. Although a fracture is seen on only 5% of emergency department knee radiographs, 86% of knee fractures result from blunt trauma. In patients with a fall or twisting injury who have focal tenderness, effusion, or inability to bear weight, radiographs should be the first imaging study obtained. If the radiograph shows no fracture, MRI is best for evaluating for a suspected meniscus or ligament tear, or the injuries from a reduced patellar dislocation. Patients with a knee dislocation should undergo radiographs and an MRI, as well as an angiographic study such as a fluoroscopic, CT, or MR angiogram. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures, by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria Vomiting in Infants up to 3 Months of Age.

Vomiting is a commonly reported symptom in infants less than three months of age. There are a multitude of pathologies to consider, both within and outside the gastrointestinal tract. In addition to conducting a thorough history and physical examination, a clinician formulates a reasonable differential diagnosis by consideration of two main factors: the infant's age and the characterization of the vomit as bilious or nonbilious. In this endeavor, the clinician is able to determine if an imaging study is needed and, if so, the urgency of the request. A review of the appropriate imaging evaluation of vomiting infants in the newborn to three-month-old age group is provided by organizing the discussion around the following three clinical scenarios: bilious vomiting, intermittent nonbilious vomiting since birth, and new-onset bilious vomiting. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria Acute Trauma to the Foot.

This ACR Appropriateness Criteria article offers imaging triage guidance for several variants of patients presenting with acute foot trauma. Patients meeting inclusion criteria for the Ottawa Rules should undergo a 3-view radiographic series. Diabetic patients with peripheral neuropathy should undergo radiography, even though they do not meet the Ottawa Rules inclusion criteria. Patients with suspected midfoot and/or Lisfranc injury should undergo 3-view radiographs with weight bearing on at least the anterior-posterior view. Patients with suspected Lisfranc injury and normal radiographs should be considered for MRI and CT on a case-by-case basis. MRI or ultrasound could confirm cases of suspected acute tendon rupture. Radiography is the initial imaging modality for suspected plantar plate injury after metatarsal-phalangeal joint injury. Weight-bearing anterior-posterior, lateral, and sesamoid axial views may detect proximal migration of the hallux sesamoids. Ultrasound or MRI can directly evaluate the capsuloligamentous complex, specifically the plantar plate. Radiography can detect radiopaque penetrating foreign bodies, and ultrasound can be helpful in detecting those that are nonradiopaque. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures, by the panel. In instances in which evidence is lacking or is not definitive, expert opinion may be used to recommend imaging and treatment.

ACR Appropriateness Criteria acute trauma to the ankle.

Acute ankle injuries are frequently diagnosed and treated in emergency departments and outpatient clinics. Recent evidence-based clinical treatment guidelines and systematic review of economic analyses support the use of 3-view (anteroposterior, lateral, and mortise) radiographic evaluation of patients meeting the criteria of the Ottawa ankle rules. Cross-sectional imaging has a limited secondary role primarily as a tool for preoperative planning and as a problem-solving technique in patients with persistent symptoms and suspected of having occult fractures. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

A radiographic scoring system to assess healing in congenital pseudarthrosis of the tibia.

The aim of this study was to determine whether an established radiographic union scoring system for tibial fracture healing (RUST) is reliable when used in neurofibromatosis (NF1) patients with congenital pseudarthrosis of the tibia (CPT) treated by intramedullary fixation. Four individuals reviewed 36 sets of radiographs from 12 NF1 patients with CPT (preoperative, and 6 months and 1 year postoperative). Intraobserver reliability (κ-value 0.89) and interobserver reliability (κ-value 0.76) were high. The modified RUST scoring system is a useful tool when faced with the challenge of postoperative radiographic evaluation of the tibia in NF1 patients with CPT.

The cross-table lateral radiograph results in a significantly increased effective radiation dose compared with the Dunn and single frog lateral radiographs.

BACKGROUND: A lateral radiograph of the proximal femur is critical in the evaluation of patients with suspected femoroacetabular impingement. Positioning patients for a cross-table lateral (XTL) image is difficult, which may result in repeat exposures and increased cumulative radiation. Alternatively, the 45-degree Dunn (Dunn) and single frog lateral (SFL) views have been shown to accurately reveal proximal femoral abnormalities in femoroacetabular impingement. The purpose of this study was to compare the effective radiation doses (ERD) for 3 lateral hip projections that provide similar diagnostic information. METHODS: Patients presenting to the adolescent hip clinic with indicated examinations were evaluated with a standard anteroposterior (AP) pelvic radiograph and one of 3 lateral hip radiographs: XTL (n=16), Dunn (n=17), or SFL (n=27). Technical exposure parameters and published reference data for an AP pelvic radiograph were used to extrapolate the ERD. A simple Pearson r correlation test determined the relationships between body mass index, age, and ERD. The rate of repeat exposures per study was calculated. RESULTS: Body mass index positively correlated (r=0.34) and age and negatively correlated (r=-0.27) with ERD. ERD was increased for the XTL (0.83±0.98 mSv) over the Dunn (0.37±0.15 mSv) and SFL (0.22±0.11 mSv; P<0.05). Repeat exposures were performed in 10.4%, 4%, and 6% of XTL, Dunn, and SFL studies, respectively. CONCLUSIONS: The ERD for a single projection is highest for the XTL, and the examination is more likely to be repeated. The XTL radiograph should be avoided whenever possible and substituted with alternative images providing similar diagnostic information, such as the Dunn or SFL, to minimize lifetime cumulative radiation exposure to the patient. LEVEL OF EVIDENCE: Level II.

ACR Appropriateness Criteria head trauma--child.

Head trauma is a frequent indication for cranial imaging in children. CT is considered the first line of study for suspected intracranial injury because of its wide availability and rapid detection of acute hemorrhage. However, the majority of childhood head injuries occur without neurologic complications, and particular consideration should be given to the greater risks of ionizing radiation in young patients in the decision to use CT for those with mild head trauma. MRI can detect traumatic complications without radiation, but often requires sedation in children, owing to the examination length and motion sensitivity, which limits rapid assessment and exposes the patient to potential anesthesia risks. MRI may be helpful in patients with suspected nonaccidental trauma, with which axonal shear injury and ischemia are more common and documentation is critical, as well as in those whose clinical status is discordant with CT findings. Advanced techniques, such as diffusion tensor imaging, may identify changes occult by standard imaging, but data are currently insufficient to support routine clinical use. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Perfusion MRI in Early Stage of Legg-Calvé-Perthes Disease to Predict Lateral Pillar Involvement: A Preliminary Study.

BACKGROUND: Current radiographic classifications for Legg-Calvé-Perthes disease cannot be applied at the early stages of the disease. The purpose of this study was to quantify the perfusion of the femoral epiphysis in the early stages of Legg-Calvé-Perthes disease with use of perfusion magnetic resonance imaging (MRI) and to determine if the extent of epiphyseal perfusion can predict the lateral pillar involvement at the mid-fragmentation stage. METHODS: Twenty-nine patients had gadolinium-enhanced perfusion MRI at the initial stage or early fragmentation stage of Legg-Calvé-Perthes disease and were followed prospectively. The percent perfusion of the whole epiphysis and its lateral third was measured by four independent observers using image analysis software. The radiographs obtained at the mid-fragmentation stage were used for the lateral pillar classification. Intraclass correlation coefficient (ICC) and logistic regression analyses were performed. RESULTS: The mean age (and standard deviation) at diagnosis was 7.7 ± 1.7 years (range, 5.3 to 11.3 years). The mean interval between the MRI and the time of maximum fragmentation was 8.2 ± 5.5 months. The interobserver ICC for the percent perfusion of the lateral third of the epiphysis was 0.90 (95% confidence interval [CI]: 0.83 to 0.95). The mean percent perfusion of the lateral third of the epiphysis was 92% ± 2%, 68% ± 18%, and 46% ± 12% for the hips in which the lateral pillar was later classified as A, B, and C, respectively (p = 0.001). When the perfusion level was ≥90% in the lateral third of the epiphysis, the odds ratio of the lateral pillar being later classified as group A, as opposed to B or C, was 72.0 (CI: 3.5 to 1476). With a perfusion level of ≤55% in the lateral third of the epiphysis, the odds ratio of the lateral pillar being later classified as group C, as opposed to A or B, was 33.3 (CI: 2.8 to 392). Similar results were obtained for the whole epiphysis. CONCLUSIONS: Perfusion MRI measurements of the total epiphysis and its lateral third obtained at the early stages of Legg-Calvé-Perthes disease were predictive of lateral pillar involvement at the mid-fragmentation stage of the disease. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

MR perfusion index as a quantitative method of evaluating epiphyseal perfusion in Legg-Calve-Perthes disease and correlation with short-term radiographic outcome: a preliminary study.

BACKGROUND: Current radiographic prognosticators of the outcome of Perthes disease can only be applied after femoral head deformity has occurred. Quantification of femoral head perfusion using the gadolinium-enhanced subtraction magnetic resonance imaging (MRI) technique may serve as an early prognosticator of outcome. The purposes of this study were 2-fold: (1) to develop a reliable method to quantify femoral head perfusion using this MRI technique; and (2) to determine whether the perfusion at early stages of Perthes disease correlates with radiographic deformity after a 2-year follow-up. METHODS: A total of 20 patients meeting the following inclusion criteria were studied: radiographs and MRI obtained of femoral heads predeformity, age between 5 and 13 years, and unilateral disease. MR perfusion index, a measure of perfusion in the epiphysis, was obtained using digital image analysis of subtraction gadolinium-enhanced MRI. Intraobserver and interobserver agreement of this index was assessed by 2 independent observers. MR perfusion index was correlated with a radiographic deformity index (a measure of femoral head deformity) obtained after a minimum of 2 years. RESULTS: The intraobserver agreement assessed by the intraclass correlation coefficient was 0.96 for observer 1 and 0.97 for observer 2. The interobserver agreement of the MR perfusion index was 0.90 for trials 1 and 2. MR perfusion index in the early stages of Perthes disease was highly variable, ranging from 0 to 0.70. After a minimum of 2 years following MRI acquisition, radiographs were obtained and evaluated using the deformity index, a continuous measure of femoral head deformity, by 2 blinded observers. Deformity index at 2-year follow-up showed moderate correlation with predeformity MR perfusion index (r=-0.56, P=0.01, R=0.31). In those patients who were treated nonoperatively, the correlation was stronger (r=-0.79, P=0.006, R=0.63). CONCLUSIONS: MR perfusion index obtained from gadolinium-enhanced subtraction MR images showed a high interobserver agreement. MR perfusion index is highly variable at early stages of Perthes disease, and a lower MR perfusion index correlated with greater radiographic deformity at the 2-year follow-up. This pilot study shows the promise of predeformity MR perfusion index as a possible early prognosticator of outcome in Perthes disease. LEVELS OF EVIDENCE: Prognostic level II.

A comparison of non-contrast and contrast-enhanced MRI in the initial stage of Legg-Calvé-Perthes disease.

BACKGROUND: A prognostic indicator of outcome for Legg-Calvé-Perthes disease (LCP) is needed to guide treatment decisions during the initial stage of the disease (stage 1), before deformity occurs. Radiographic prognosticators are applicable only after fragmentation (stage II). OBJECTIVE: We investigated pre- and postcontrast MRI in depicting stage I femoral head involvement. MATERIALS AND METHODS: Thirty children with stage I LCP underwent non-contrast coronal T1 fast spin-echo (FSE) and corresponding postcontrast fat-suppressed T1-weighted fast spin-echo (FSE) sequences to quantify the extent of femoral head involvement. Three pediatric radiologists and one pediatric orthopedic surgeon independently measured central head involvement. RESULTS: Interobserver reliability of percent head involvement using non-contrasted MR images had intraclass correlation coefficient (ICC) of 0.72. Postcontrast MRI improved interobserver reliability (ICC 0.82). Qualitatively, the area of involvement was more clearly visible on contrast-enhanced MRI. A comparison of results obtained by each observer using the two MRI techniques showed no correlation. ICC ranged from -0.08 to 0.03 for each observer. Generally, greater head involvement was depicted by contrast compared with non-contrast MRI (Pearson r = -0.37, P = 0.04). CONCLUSION: Pre- and postcontrast MRI assess two different components of stage I LCP. However, contrast-enhanced MRI more clearly depicts the area of involvement.

Magnetic resonance imaging of the congenital clubfoot treated with the French functional (physical therapy) method.

The purpose of this study was to assess magnetic resonance imaging (MRI) changes that occur in clubfeet after nonoperative treatment with the French functional method, specifically pertaining to the chondro-osseous anatomy and the joint relationships. The magnetic resonance images were obtained in 6 infants before treatment and 3 months later. The MRI protocol described previously for clubfeet which were treated by the Ponseti method (J Pediatr Orthop. 2001;21:719) was closely adhered to, except that no sedation was allowed by our institutional review board. The severity of the clubfoot deformities before treatment made assessment of the tibiotalar, talonavicular, and talocalcaneal joint relationships difficult in some feet. Despite this, improvements were noted after treatment in tibiotalar plantarflexion, the talonavicular relationship, the calcaneocuboid relationship, and the varus position of the calcaneus. The wedge shape of both the navicular and distal end of the calcaneus that occasionally was noted on the MRI before treatment improved after therapy. Although improved clinically, persistent equinus of the calcaneus on MRI was significant in 2 feet and was associated with slight dorsal displacement of the cuboid on the calcaneus (MRI evidence of rocker bottom). As noted with use of the Ponseti nonoperative treatment method, the chondro-osseous abnormalities seen on MRI studies in congenital clubfoot improve after treatment with the French functional (physical therapy) method, with the exception of equinus.