Maria A. Bedoya

Diagnostic Performance of Whole-Body MRI as a Tool for Cancer Screening in Children With Genetic Cancer-Predisposing Conditions

OBJECTIVE Children with cancer-predisposing conditions are at increased risk to develop and die of cancer. Limited data exist on the utility of whole-body MRI as a cancer screening tool in children. In this study, we examined the diagnostic performance of whole-body MRI as a mechanism of tumor surveillance for children at increased genetic risk for cancer. MATERIALS AND METHODS Twenty-four children (six boys and 18 girls) with a mean age of 11.2 years (range, 2.1-18.2 years) underwent 50 unenhanced whole-body MRI examinations over a 5-year period. Scans were retrospectively reviewed and assessed for image quality; sequences performed; and the presence of osseous, soft-tissue, or solid organ abnormalities. Findings suggestive of a malignancy were stratified by risk as low (< 20% chance for cancer), moderate (20-80%), or high (> 80%). MRI findings were correlated with medical records, biopsy results, or additional follow-up imaging; biopsy and follow-up were considered as the reference standards. RESULTS Forty-eight of 50 (96%) examinations were of very good quality. Nine findings suspicious for malignancy were identified, including two high-risk, two moderate-risk, and five low-risk lesions. One high-risk lesion was proven by biopsy to be a papillary thyroid carcinoma, with the remaining lesions deemed nonmalignant. The sensitivity of whole-body MRI was 100%; specificity, 94%; positive predictive value, 25%; and negative predictive value (NPV), 100%. CONCLUSION Unenhanced whole-body MRI is safe and produces excellent images. The high sensitivity, specificity, and NPV make whole-body MRI a valuable cancer screening tool in children with a genetic predisposition for cancer.

Normal Skeletal Maturation and Imaging Pitfalls in the Pediatric Shoulder

A growing number of magnetic resonance (MR) imaging studies of the shoulder are being performed as a result of greater and earlier participation of children and adolescents in competitive sports such as softball and baseball. However, scant information is available regarding the MR imaging features of the normal sequential development of the shoulder. The authors discuss the radiographic and MR imaging appearances of the normal musculoskeletal maturation patterns of the shoulder, with emphasis on (a) development of secondary ossification centers of the glenoid (including the subcoracoid and peripheral glenoid ossification centers); (b) development of preossification and secondary ossification centers of the humeral head and the variable appearance and number of the secondary ossification centers of the distal acromion, with emphasis on the formation of the os acromiale; (c) development of the growth plates, glenoid bone plates, glenoid bare area, and proximal humeral metaphyseal stripe; and (d) marrow signal alterations in the distal humerus, acromion, and clavicle. In addition, the authors discuss various imaging interpretation pitfalls inherent to the normal skeletal maturation of the shoulder, examining clues that may help distinguish normal development from true disease (eg, osteochondral lesions, labral tears, abscesses, fractures, infection, tendon disease, acromioclavicular widening, and os acromiale). Familiarity with the timing, location, and appearance of maturation patterns in the pediatric shoulder is crucial for correct image interpretation.

Dynamic Gadolinium-Enhanced MRI of the Proximal Femur: Preliminary Experience in Healthy Children

OBJECTIVE The purpose of this study is to use dynamic contrast-enhanced MRI to evaluate the perfusion characteristics of the proximal femur in the growing skeleton. MATERIALS AND METHODS We evaluated 159 subjects (mean age, 5.67 years) who underwent a well-controlled protocol of contrast-enhanced MRI of the abdomen and hips. Perfusion and permeability parameters (enhancement ratio peak, AUC, time to peak, and rate of extraction) for six regions of the proximal femur were calculated. RESULTS A decrease with age was found for all contrast kinetics parameters in all regions (p < 0.001). Perfusion parameters differed between the regions (p < 0.001). The highest perfusion and permeability parameters were found in the metaphyseal spongiosa, metaphyseal marrow, and periosteum. The metaphyseal spongiosa had a highly vascular pattern of enhancement and showed the highest enhancement ratio peak, AUC, and rate of extraction and the lowest time to peak. The metaphyseal marrow showed a vascular pattern of enhancement with a lower peak compared with the metaphyseal spongiosa. The periosteum showed prompt nonvascular contrast enhancement that reached a plateau that remained elevated. CONCLUSION The highest enhancement was seen in areas involved with growth: the metaphyseal spongiosa, which is related to endochondral ossification, and the periosteal cambium, which is related to membranous ossification. The enhancement characteristics are radically different: in the spongiosa; enhancement is brisk and declines, with a vascular pattern, whereas contrast uptake increases with time in the periosteum. Recognition of normal enhancement patterns of the proximal femur is important for distinguishing normal development from pathologic processes.

Overuse injuries in children.

Abstract There has been a substantial increase in the number of children participating in organized competitive sports, which has led to a surge in the number of both acute and overuse injuries. To prevent further complications such as limb deformity and disability, radiologists must be familiar with typical overuse injury patterns in children. Traction apophysitis, chronic physeal injury, and stress fractures are the principal overuse injuries. This article reviews overuse injuries in children with an emphasis on the role of magnetic resonance imaging in diagnosis, prognosis, and treatment.

Common Patterns of Congenital Lower Extremity Shortening: Diagnosis, Classification, and Follow-up

Congenital lower limb shortening is a group of relatively rare, heterogeneous disorders. Proximal focal femoral deficiency (PFFD) and fibular hemimelia (FH) are the most common pathologic entities in this disease spectrum. PFFD is characterized by variable degrees of shortening or absence of the femoral head, with associated dysplasia of the acetabulum and femoral shaft. FH ranges from mild hypoplasia to complete absence of the fibula with variable shortening of the tibia. The development of the lower limb requires complex and precise gene interactions. Although the etiologies of PFFD and FH remain unknown, there is a strong association between the two disorders. Associated congenital defects in the lower extremity are found in more than 50% of patients with PFFD, ipsilateral FH being the most common. FH also has a strong association with shortening and bowing of the tibia and with foot deformities such as absence of the lateral rays of the foot. Early diagnosis and radiologic classification of these abnormalities are imperative for appropriate management and surgical planning. Plain radiography remains the main diagnostic imaging modality for both PFFD and FH, and appropriate description of the osseous abnormalities seen on radiographs allows accurate classification, prognostic evaluation, and surgical planning. Minor malformations may commonly be misdiagnosed.

Quantification of Bone Marrow Involvement in Treated Gaucher Disease With Proton MR Spectroscopy: Correlation With Bone Marrow MRI Scores and Clinical Status

OBJECTIVE The objective of our study was to use proton MR spectroscopy (MRS) to quantitatively evaluate bone marrow infiltration by measuring the fat fraction (FF) and to compare the FF with semiquantitative bone marrow MRI scores and clinical status in children treated for type 1 Gaucher disease (GD). SUBJECTS AND METHODS Over a 2-year period, we prospectively evaluated 10 treated GD patients (six males, four females; median age, 15.1 years) and 10 healthy age-matched control subjects (five males, five females; median age, 15.3 years) using 3-T proton MRS of L5 and the femoral neck. Water and lipid AUCs were measured to calculate the FF. Two blinded pediatric musculoskeletal radiologists performed a semiquantitative analysis of the conventional MR images using the bone marrow burden score and modified Spanish MRI score. We evaluated symptoms, spleen and liver volumes, platelet levels, hemoglobin levels, and bone complications. RESULTS In the femur, the FF was higher in the control subjects (median, 0.71) than the GD patients (0.54) (p = 0.02). In L5, the difference in FF--higher FF in control subjects (0.37) than in GD patients (0.26)--was not significant (p = 0.16). In both groups and both regions, the FF increased with patient age (p < 0.02). Semiquantitative scores showed no differences between control subjects and treated GD patients (p > 0.11). Eight of 10 GD patients were asymptomatic and two had chronic bone pain. The median age of patients at symptom onset was 4.0 years, the median age of patients at the initiation of enzyme replacement therapy was 4.3 years, and the median treatment duration was 10.2 years. Hemoglobin level, platelet count, and liver volume at MRI were normal. Mean pretreatment spleen volume (15.4-fold above normal) decreased to 2.8-fold above normal at the time of MRI (p = 0.01). CONCLUSION Proton MRS detected FF differences that were undetectable using conventional MRI; for that reason, proton MRS can be used to optimize treatment of GD patients.

Effect of Intravenous Administration of Contrast Media on Serum Creatinine Levels in Neonates

Purpose To assess the effect of intravenous contrast media on renal function in neonates. Materials and Methods Institutional review board approval was obtained with waiver of consent. Electronic health records from January 2011 to April 2013 were reviewed retrospectively. Measures of renal function were obtained in inpatient neonates who underwent magnetic resonance (MR) imaging or computed tomography (CT) and for whom serum creatinine (Cr) levels were obtained within 72 hours before imaging and at least one time after imaging (>1 day after administration of contrast material). A total of 140 neonates who received contrast material (59 who underwent CT with iohexol or iodixanol and 81 who underwent MR imaging with gadopentetate dimeglumine) were identified. These neonates were frequency matched according to sex, gestational and postnatal age, and preimaging serum Cr levels with neonates who underwent unenhanced MR imaging or CT. Cr levels and glomerular filtration rates (GFRs) were grouped according to when they were obtained (before imaging, 1-2 days after imaging, 3-5 days after imaging, 6-9 days after imaging, 10-45 days after imaging, and more than 45 days after imaging). Serum Cr levels and GFRs for each time period were compared between groups by using hierarchic regressions or χ2 or Fisher exact tests and with repeated-measures analysis of variance to compare groups on the rate of change in serum Cr levels and GFRs from before to after imaging. Results Cr levels decreased and GFRs increased in both groups from before to after imaging (CT group, P ≤ .01; MR imaging group, P ≤ .01). The neonates who underwent contrast material-enhanced imaging and the neonates who underwent unenhanced imaging showed similar serum Cr levels at all examined time periods. Groups also did not differ in the proportion of neonates with serum Cr levels higher than the reference range (>0.4 mg/dL) at any time point (iodine- [P > .12] or gadolinium-based [P > .13] contrast material). Similar findings were observed for GFRs. None of the neonates developed nephrogenic systemic fibrosis. Conclusion In the absence of known renal failure, neonates receiving standard inpatient care do not appear to be at increased risk for developing renal toxicity due to administration of intravenous iodine- and gadolinium-based contrast material.

Ultrasound Tutorials in Under 10 Minutes: Experience and Results.

OBJECTIVE The objective of the present study was to validate the use of web-based tutorials to teach technical skills in pediatric ultrasound. MATERIALS AND METHODS A series of 10 video tutorials, each of which was less than 10 minutes long, was created to improve the education of radiology trainees in terms of their ultrasound technique. Pediatric radiology fellow trainees from our institution in the United States and radiology resident trainees from our partner institution in Ethiopia were invited to participate in the study. Validation of the video tutorials was performed using two learning modules that focused on the renal bladder and the right upper quadrant (RUQ). Pretest and posttest skill and confidence assessments were also conducted. After watching the tutorials, the trainees completed questionnaires that assessed the reach, appeal, and learning effectiveness of the modules. RESULTS Ten fellow trainees and eight resident trainees participated in the study. The fellows were invited to evaluate both the RUQ and the renal bladder learning modules, whereas the residents evaluated the RUQ module only. Before reviewing the RUQ module, the fellows had performed a median of four RUQ ultrasound examinations, whereas the residents had performed a median of 400 RUQ ultrasound examinations. After the trainees viewed the learning module, the median skills test scores of the fellows increased from 20 to 37.5 (highest possible score, 45) (p < 0.01), and those of the residents increased from 38 to 40 (highest possible score, 40) (p = 0.04). With a total possible score of 15, the median confidence score improved from 8 to 11 for fellows (p < 0.01) and from 13.5 to 14.5 for residents (p = 0.04). After the fellows viewed the renal bladder learning module, their median skills test scores increased from 20 to 37.5 (highest possible score, 40) (p < 0.01), and their median confidence score increased from 8.5 to 11 (highest possible score, 15) (p = 0.01). Trainees gave the tutorials positive ratings overall. CONCLUSION Radiology fellow trainees and resident trainees with disparate backgrounds in ultrasound showed significant improvement in their technical skills in pediatric ultrasound and confidence after viewing the tutorials. The web-based design of the tutorials allows integration of international pediatric radiology training communities.

Bilateral agenesis of the anterior cruciate ligament: MRI evaluation.

Bilateral agenesis of the anterior cruciate ligament (ACL) is extremely rare. We describe a 13-year-old girl who presented with bilateral knee pain without history of trauma; she has two family members with knee instability. Magnetic resonance imaging showed bilateral absence of the ACL, and medial posterior horn meniscal tears. Bilateral arthroscopic partial meniscectomy and anterior cruciate ligament reconstruction was performed.

Diffusion-Tensor Imaging of the Physes: A Possible Biomarker for Skeletal Growth—Experience with 151 Children

Purpose To determine the changes of diffusion-tensor imaging (DTI) and tractography in the distal femur and proximal tibia related to age, sex, and height. Materials and Methods Following institutional review board approval, with waiver of consent and with HIPAA compliance, the authors retrospectively analyzed DTI images of the knee in 151 children, 73 girls (median age, 14.1 years; range, 6.5-17.8 years) and 78 boys (median age, 16.6 years; range, 6.9-17.9 years), studied from January 2013 to October 2014. At sagittal echo-planar DTI (20 directions, b values of 0 and 600 sec/mm2), regions of interest were placed in the tibial and femoral physes. Using a fractional anisotropy threshold of 0.15 and an angle threshold of 40°, the authors performed tractography and measured apparent diffusion coefficient (ADC) and tract length and volume. Changes related to age, sex, and height were evaluated by using fitted nonlinear polynomial functions on bootstrapped samples. Results Femoral tract volume and length increased and then decreased with age (P < .001); the peaks of femoral tract volume are consistent with the growth spurt, occurring earlier in girls (10.8 years) than in boys (13.0 years) (P < .001). Girls had smaller tract volumes in comparison to boys (P = .013). ADC peaks 2 years earlier than tract volume (girls at 9.3 years, boys at 11.0 years). Girls with greater than 50th percentile of height had longer tracts and greater tract volumes compared with girls with less than 50th percentile (P < .020). DTI parameters of boys do not correlate with percentile of height (P > .300). Conclusion DTI of the physis and metaphysis shows greater tract length and volumes in subjects who are at ages when the growth is fastest. ADC and tract length and volume have an earlier and smaller peak in girls than in boys. Femoral tract length and volume are larger in taller girls.