Jacob L. Jaremko

Value and Limitations of Diffusion-Weighted Imaging in Grading and Diagnosis of Pediatric Posterior Fossa Tumors

SUMMARY: DWI reportedly accurately differentiates pediatric posterior fossa tumors, but anecdotal experience suggests limitations. In 3 years, medulloblastoma and JPA were differentiated by DWI alone in 23/26 cases (88%). Ependymoma (n = 5) could not be reliably differentiated from medulloblastoma or JPA. A trend toward increased diffusion restriction in higher grade tumors (1/14 grade I, 7%; 9/12 grade IV, 75%) had too much overlap to predict the grade of individual cases. The overlap in ADC between tumor types appeared partly due to technical factors (in small, heterogeneous, calcific, or hemorrhagic tumors) but also likely reflected true histologic variability, given that our 3 overlap cases included a desmoplastic medulloblastoma, an anaplastic ependymoma, and a JPA with restricted diffusion in its nodule. Simple structural features (macrocystic tumor, location off midline) aided in distinguishing JPA from the other tumors in these cases.

Incident vertebral fractures and risk factors in the first three years following glucocorticoid initiation among pediatric patients with rheumatic disorders

Vertebral fractures are an important yet underrecognized manifestation of osteoporosis in children with chronic, glucocorticoid‐treated illnesses. Our goal was to determine the incidence and clinical predictors of vertebral fractures in the 3 years following glucocorticoid initiation among pediatric patients with rheumatic disorders. Incident vertebral fractures were evaluated according to the Genant semiquantitative method on lateral radiographs at baseline and then annually in the 3 years following glucocorticoid initiation. Extended Cox models were used to assess the association between vertebral fractures and clinical risk predictors. A total of 134 children with rheumatic disorders were enrolled in the study (mean ± standard deviation (SD) age 9.9 ± 4.4 years; 65% girls). The unadjusted vertebral fracture incidence rate was 4.4 per 100 person‐years, with a 3‐year incidence proportion of 12.4%. The highest annual incidence occurred in the first year (6.0%; 95% confidence interval (CI) 2.9% to 11.7%). Almost one‐half of the patients with fractures were asymptomatic. Every 0.5 mg/kg increase in average daily glucocorticoid (prednisone equivalents) dose was associated with a twofold increased fracture risk (hazard ratio (HR) 2.0; 95% CI 1.1 to 3.5). Other predictors of increased vertebral fracture risk included: (1) increases in disease severity scores between baseline and 12 months; (2) increases in body mass index Z‐scores in the first 6 months of each 12‐month period preceding the annual fracture assessment; and (3) decreases in lumbar spine bone mineral density Z‐scores in the first 6 months of glucocorticoid therapy. As such, we observed that a clinically significant number of children with rheumatic disorders developed incident vertebral fractures in the 3 years following glucocorticoid initiation. Almost one‐half of the children were asymptomatic and thereby would have been undiagnosed in the absence of radiographic monitoring. In addition, discrete clinical predictors of incident vertebral fractures were evident early in the course of glucocorticoid therapy.

Incident Vertebral Fractures in Children With Leukemia During the Four Years Following Diagnosis

OBJECTIVES The purpose of this article was to determine the incidence and predictors of vertebral fractures (VF) during the 4 years after diagnosis in pediatric acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS Children were enrolled within 30 days of chemotherapy initiation, with incident VF assessed annually on lateral spine radiographs according to the Genant method. Extended Cox models were used to assess the association between incident VF and clinical predictors. RESULTS A total of 186 children with ALL completed the baseline evaluation (median age, 5.3 years; interquartile range, 3.4-9.7 years; 58% boys). The VF incidence rate was 8.7 per 100 person-years, with a 4-year cumulative incidence of 26.4%. The highest annual incidence occurred at 12 months (16.1%; 95% confidence interval [CI], 11.2-22.7), falling to 2.9% at 4 years (95% CI, 1.1-7.3). Half of the children with incident VF had a moderate or severe VF, and 39% of those with incident VF were asymptomatic. Every 10 mg/m(2) increase in average daily glucocorticoid dose (prednisone equivalents) was associated with a 5.9-fold increased VF risk (95% CI, 3.0-11.8; P < .01). Other predictors of increased VF risk included VF at diagnosis, younger age, and lower spine bone mineral density Z-scores at baseline and each annual assessment. CONCLUSIONS One quarter of children with ALL developed incident VF in the 4 years after diagnosis; most of the VF burden was in the first year. Over one third of children with incident VF were asymptomatic. Discrete clinical predictors of a VF were evident early in the patients clinical course, including a VF at diagnosis.

MRI of the SI joints commonly shows non-inflammatory disease in patients clinically suspected of sacroiliitis.

PURPOSE To determine the prevalence of clinically relevant non-inflammatory disease on MRI of the sacroiliac (SI) joints in patients suspected of sacroiliitis. To assess the added value of axial imaging of the pelvis in these patients. METHODS In a retrospective study of 691 patients undergoing MRI of the SI joints from January 2006 to December 2012 for inflammatory back pain the prevalence of sacroiliitis and non-inflammatory disease was recorded. RESULTS In 285 (41%) patients MRI did not show any abnormal findings. In 36% of patients MRI features of sacroiliitis were present. Spinal degenerative changes were the most common non-inflammatory finding in 305 patients (44.1%) and consisted of disc degeneration in 222 (32%) patients, facet joint arthrosis in 58 (8.4%) patients and disc herniation in 25 (3.6%) patients. Hip joint disease in 44 (6.4%) patients, lumbosacral transitional anomaly in 41 (5.9%) patients, SI joint degenerative changes in 25 (3.6%) patients and diffuse idiopathic skeletal hyperostosis in 24 (3.5%) patients were also common. Osteitis condensans ilii in 17 (2.5%) patients, tumour in 11 (1.6%) patients, fracture in 8 (1.2%) patients, infection in 4 (0.6%) patients and acute spondylolysis in 2 patients (0.3%) were less frequently seen. CONCLUSION Our study shows that non-inflammatory disease is more common than true sacroiliitis on MRI of the SI joints in patients with inflammatory type back pain. Axial pulse sequences may demonstrate unexpected findings that remain undetected if only coronal images are obtained. Clinical relevance statement:, MRI of the SI joints may demonstrate conditions that clinically mimic sacroiliitis. Axial imaging of the pelvis may help detect these unexpected findings.

MR imaging findings and MR criteria for instability in osteochondritis dissecans of the elbow in children

PURPOSE Osteochondritis dissecans (OCD) of the elbow is an uncommon cause of elbow pain in adolescents and occurs at different locations in the elbow joint. Early diagnosis and treatment may prevent surgery. The aim of the study is to describe the MR imaging features of OCD at initial imaging, and to correlate these findings with surgical findings of stability and instability with arthroscopic findings as the reference standard. METHODS Patients were identified through a keyword search of the radiology information system from 2000 to 2009. Twenty-five patients (26 elbows) with OCD of the elbow were identified (age 10.4-18 years, mean age 14 years). MR studies were retrospectively reviewed by two radiologists in consensus to define MR imaging findings and to determine the presence of previously described MR imaging criteria for OCD instability (i.e., high T2 signal rim, surrounding cysts, high T2 signal fracture line, fluid-filled osteochondral defect). Sensitivity of the individual and combined criteria was calculated. RESULTS OCD occurred in the capitellum in 24 patients (92%), in the trochlea in 2 patients (8%) and radial head in 1 patient (4%). Loose bodies were identified in 11 (42%) patients. Eighteen patients demonstrated MRI findings in keeping with unstable lesions. In all 11 patients who had surgery the surgical findings of instability correlated with the MRI findings. When combined, the MR criteria were 100% sensitive for instability of OCD lesions of the elbow. CONCLUSION The vast majority of OCD of the elbow occurs in the capitellum. When used together, the MR criteria for instability were 100% sensitive for evaluation OCD lesions of the elbow.

Three-Dimensional Intercondylar Notch Volumes in a Skeletally Immature Pediatric Population: A Magnetic Resonance Imaging–Based Anatomic Comparison of Knees With Torn and Intact Anterior Cruciate Ligaments

PURPOSE To determine whether 3-dimensional notch volume, measured with magnetic resonance imaging (MRI), differs significantly between knees with torn and intact anterior cruciate ligaments (ACLs) after sports injury in a skeletally immature pediatric population. METHODS MRI studies of 50 pediatric patients (age range, 10 to 17 years) with ACL tears were compared with 50 age- and sex-matched intact-ACL control patients. All patients had open physes and underwent MRI after a sports injury. Notch volume was calculated through manual segmentation of notch boundaries seen on axial 1.5-T proton density-weighted images. Two-dimensional (2D) measurements (notch width and notch width index) were made on coronal proton density-weighted MRI studies. Notch volume was compared between groups by use of the Mann-Whitney U test. Pearson correlation coefficients were also calculated between indices. RESULTS Notch volume was significantly lower in knees with ACL tears than in control knees (5.5 ± 1.1 cm(3)v 6.4 ± 1.5 cm(3), P = .002), whereas 2D notch width and notch width index did not differ significantly between these groups. Girls had significantly smaller notch volumes than boys (5.4 ± 1.2 cm(3)v 6.5 ± 1.3 cm(3), P < .001). Notch volume was not correlated with age but was moderately correlated with 2D notch width (r = 0.485, P < .001). CONCLUSIONS In adolescent patients with sports injuries, the 3-dimensional notch volume was significantly smaller in knees with ACL tears than in intact-ACL control knees. Notch volume was also significantly smaller in girls than in boys and did not vary significantly with age. LEVEL OF EVIDENCE Level III, case-control study.

Diagnostic Utility of Magnetic Resonance Imaging and Radiography in Juvenile Spondyloarthritis: Evaluation of the Sacroiliac Joints in Controls and Affected Subjects

Objective. To compare the utility of radiography and magnetic resonance imaging (MRI) for the diagnosis of juvenile-onset spondyloarthritis in pediatric patients presenting with low back and/or sacroiliac (SI) pain of potentially inflammatory etiology. Methods. Radiographs and MRI studies of the SI joints in 26 patients with juvenile spondyloarthritis (JSpA) and 35 controls were assessed independently by 2 radiologists, with discrepancies arbitrated by a third. Radiographs and MRI were blinded and read in separate batches in random order. Results. Erosion was common and was the most useful diagnostic feature on radiography [positive likelihood ratio (LR) = 3.5] and was especially diagnostic of SpA on MRI (LR = 6.7). Subchondral sclerosis was common but was the least specific feature for both modalities. Joint space narrowing had some utility on radiography (LR = 2.0) and MRI (LR = 2.7) but was uncommon and had poor reader reliability. Bone marrow edema (LR = 3.1) and subarticular fat infiltration (LR = 4.5), detectable only on MRI, were both useful features. Global diagnostic impression of MRI (LR = 9.4) had very high utility for the diagnosis of JSpA, exceeding radiography (LR = 4.4) because of superior specificity. In addition, global diagnosis of SpA is much more reliably made on MRI (κ = 0.80) compared to radiography (κ = 0.30). Conclusion. Specificity and reliability of MRI of the SI joints are superior to radiography for the diagnosis of juvenile-onset SpA and, where available, MRI should replace radiography as the first line of investigation.

Preliminary Validation of 2 Magnetic Resonance Image Scoring Systems for Osteoarthritis of the Hip According to the OMERACT Filter

Objective. Development of a validated magnetic resonance image (MRI) scoring system is essential in hip OA because radiographs are insensitive to change. We assessed the feasibility and reliability of 2 previously developed scoring methods: (1) the Hip Inflammation MRI Scoring System (HIMRISS) and (2) the Hip Osteoarthritis MRI Scoring System (HOAMS). Methods. Six readers (3 radiologists, 3 rheumatologists) participated in 2 reading exercises. In Reading Exercise 1, MRI of the hip of 20 subjects were read at a single time point followed by further standardization of methodology. In Reading Exercise 2, MRI of the hip of 18 subjects from a randomized controlled trial, assessed at 2 timepoints, and 27 subjects from a cross-sectional study were read for HIMRISS and HOAMS bone marrow lesions (BML) and synovitis. Reliability was assessed using intraclass correlation coefficient (ICC) and kappa statistics. Results. Both methods were considered feasible. For Reading 1, HIMRISS ICC were 0.52, 0.61, 0.70, and 0.58 for femoral BML, acetabular BML, effusion, and total scores, respectively; and for HOAMS, summed BML and synovitis ICC were 0.52 and 0.46, respectively. For Reading 2, HIMRISS and HOAMS ICC for BML and synovitis-effusion improved substantially. Interobserver reliability for change scores was 0.81 and 0.71 for HIMRISS femoral and HOAMS summed BML, respectively. Responsiveness and discrimination was moderate to high for synovitis-effusion. Significant associations were noted between BML or synovitis scores and Western Ontario and McMaster Universities Osteoarthritis Index pain scores for baseline values (p ≤ 0.001). Conclusion. The BML and synovitis-effusion components of both HIMRISS and HOAMS scoring systems are feasible and reliable, and should be validated further.

Real-time visualization of joint cavitation.

Cracking sounds emitted from human synovial joints have been attributed historically to the sudden collapse of a cavitation bubble formed as articular surfaces are separated. Unfortunately, bubble collapse as the source of joint cracking is inconsistent with many physical phenomena that define the joint cracking phenomenon. Here we present direct evidence from real-time magnetic resonance imaging that the mechanism of joint cracking is related to cavity formation rather than bubble collapse. In this study, ten metacarpophalangeal joints were studied by inserting the finger of interest into a flexible tube tightened around a length of cable used to provide long-axis traction. Before and after traction, static 3D T1-weighted magnetic resonance images were acquired. During traction, rapid cine magnetic resonance images were obtained from the joint midline at a rate of 3.2 frames per second until the cracking event occurred. As traction forces increased, real-time cine magnetic resonance imaging demonstrated rapid cavity inception at the time of joint separation and sound production after which the resulting cavity remained visible. Our results offer direct experimental evidence that joint cracking is associated with cavity inception rather than collapse of a pre-existing bubble. These observations are consistent with tribonucleation, a known process where opposing surfaces resist separation until a critical point where they then separate rapidly creating sustained gas cavities. Observed previously in vitro, this is the first in-vivo macroscopic demonstration of tribonucleation and as such, provides a new theoretical framework to investigate health outcomes associated with joint cracking.

Incidence and Significance of Inconclusive Results in Ultrasound for Appendicitis in Children and Teenagers

Purpose Frustratingly, sonography to assess for appendicitis in children often leads to an inconclusive report (eg, “suspicious for appendicitis”) or nonvisualization of the appendix. To aid in planning who to image and how to interpret the results, we investigated whether these 2 results were more frequent in teenagers than preteens and the prevalence of appendicitis associated with each result. Methods We retrospectively reviewed sonographic and surgical findings in patients <18 years (n = 189) referred with clinical suspicion of appendicitis over a 12-month period. Children (≤12.0 years old; n = 86) and teens (>12.0 years old; n = 103) were compared. Results Prevalence of appendicitis was 34% in each group, similar to other centres; 0% for those with negative ultrasound reports (0/35), 10% for nonvisualized appendix (8/84), 68% for inconclusive report (15/22), and 85% for positive ultrasound (41/48). Teens were significantly more likely to have an inconclusive ultrasound. Inconclusive reports were because of borderline findings (eg, appendix size near 6 mm; 9/22), body habitus, bowel gas, or unusual findings due in retrospect to perforation. The rate of nonvisualization of the appendix did not vary significantly with age (42% vs 47%). Conclusion An inconclusive result of ultrasound for appendicitis was significantly more frequent in teens than in preteens and carried a high (68%) likelihood of appendicitis. Conversely, a nonvisualized appendix was equally frequent in teens and preteens, and had a low likelihood of appendicitis (only 10% positive). These findings encourage the use of ultrasound in preteens in particular and can assist interpretation of these common results.