Michael M. Moore

An implemented MRI program to eliminate radiation from the evaluation of pediatric appendicitis

BACKGROUND Recent efforts have been directed at reducing ionizing radiation delivered by CT scans to children in the evaluation of appendicitis. MRI has emerged as an alternative diagnostic modality. The clinical outcomes associated with MRI in this setting are not well-described. METHODS Review of a 30-month institutional experience with MRI as the primary diagnostic evaluation for suspected appendicitis (n=510). No intravenous contrast, oral contrast, or sedation was administered. Radiologic and clinical outcomes were abstracted. RESULTS MRI diagnostic characteristics were: sensitivity 96.8% (95% CI: 92.1%-99.1%), specificity 97.4% (95% CI: 95.3-98.7), positive predictive value 92.4% (95% CI: 86.5-96.3), and negative predictive value 98.9% (95% CI: 97.3%-99.7%). Radiologic time parameters included: median time from request to scan, 71 minutes (IQR: 51-102), imaging duration, 11 minutes (IQR: 8-17), and request to interpretation, 2.0 hours (IQR: 1.6-2.6). Clinical time parameters included: median time from initial assessment to admit order, 4.1 hours (IQR: 3.1-5.1), assessment to antibiotic administration 4.7 hours (IQR: 3.9-6.7), and assessment to operating room 9.1 hours (IQR: 5.8-12.7). Median length of stay was 1.2 days (range: 0.2-19.5). CONCLUSION Given the diagnostic accuracy and favorable clinical outcomes, without the potential risks of ionizing radiation, MRI may supplant the role of CT scans in pediatric appendicitis imaging.

Ethylene Glycol Toxicity: Chemistry, Pathogenesis, and Imaging

The ingestion of ethylene glycol results in toxicity with characteristic chemical, pathological, and imaging findings. In the case presented, magnetic resonance imaging demonstrated bilateral symmetric hyperintensity within the basal ganglia, thalami, and brainstem. Ethylene glycol toxicity also resulted in restricted diffusion within the white matter tracts of the corona radiata, a finding not previously described in the literature. In the acute clinical setting, ethylene glycol toxicity is an important differential consideration of the pathologies involving the deep grey matter nuclei.

Alternative diagnoses at paediatric appendicitis MRI

As the utilization of MRI in the assessment for paediatric appendicitis increases in clinical practice, it is important to recognize alternative diagnoses as the cause of abdominal pain. The purpose of this review is to share our institutions experience using MRI in the evaluation of 510 paediatric patients presenting with suspected appendicitis over a 30 month interval (July 2011 to December 2013). An alternative diagnosis was documented in 98/510 (19.2%) patients; adnexal pathology (6.3%, n = 32), enteritis-colitis (6.3%, n = 32), and mesenteric adenitis (2.2%, n = 11) comprised the majority of cases. These common entities and other less frequent illustrative cases obtained during our overall institutional experience with MRI for suspected appendicitis are reviewed.

Bisphosphonate therapy for chronic recurrent multifocal osteomyelitis

This patient was diagnosed with chronic multifocal recurrent osteomyelitis of the ankle approximately 4 years prior to the presented images. Multiple treatments were administered, most notably monthly intravenous pamidronate, a therapy that was continued for 17 months, until recrudescent disease prompted a change in therapy. At the time of the presented images, the patient had not received bisphosphonate therapy for 2 years. Bisphosphonates are a class of medications used primarily in adult patients with decreased bone mineral density. When the drug is incorporated into the hydroxyapatite matrix of nascent bone, osteoclastic activity is inhibited, and as a result, bone mineral density increases. Also used in patients with expansile bone lesions, the decrease in osteoclastic activity serves to slow the progression of enlargement, demonstrating an analgesic effect. Finally, it is thought that bisphosphonates engender a direct anti-inflammatory response by altering the inflammatory cascade [1]. In children, bisphosphonates have been used for the treatment of conditions resulting in low bone mineral density, such as osteogenesis imperfecta [2]. Furthermore, several recent studies have demonstrated the effectiveness of bisphosphonate therapy as a second-line treatment for CRMO-associated pain [3]. Most CRMO treatment regimens consist of daily infusions of IV pamidronate for 1–3 days, repeated every 3 months [1, 3, 4]. Pain relief is usually rapid, within days of initiation, and resolution of inflammation by MR imaging follows in up to 80 % of patients [2]. Radiologically, the cyclical inhibition of osteoclast activity in the skeletally immature patient gives rise to dense metaphyseal bands migrating longitudinally from the zone of provisional calcification into the diaphysis, as previously described [5, 6]. Additionally, undertubulation of the affected areas, as well a “bone within a bone” appearance can be seen [7]. The presence of metaphyseal bands engenders differential considerations such as lead poisoning and hypervitaminosis D, as well as causes of standard growth recovery lines (times of malnutrition, severe illness, etc.). As none of the causes of metaphyseal bands are common, the interpreting radiologist may be inspired to suggest further testing when confronted with this unusual finding. However, the recognition of focal undertubulation (most striking at the distal femur in this case) helps cinch the diagnosis. Recognition of these findings can be clinically important, as the abrupt change of bone mineral density at the dense bands has been implicated as a stress riser, similar to the interface between a prosthesis and native bone [8]. The potential increase in fracture risk presented by these bands may prompt a change in the duration of therapy.

MRI for clinically suspected pediatric appendicitis: case interpretation

As utilization of MRI for clinically suspected pediatric appendicitis becomes more common, there will be increased focus on case interpretation. The purpose of this pictorial essay is to share our institution’s case interpretation experience. MRI findings of appendicitis include appendicoliths, tip appendicitis, intraluminal fluid–debris level, pitfalls of size measurements, and complications including abscesses. The normal appendix and inguinal appendix are also discussed.

Single injection, inspiratory/expiratory high-pitch dual-source CT angiography for median arcuate ligament syndrome: Novel technique for a classic diagnosis

This article discusses a novel technique for dynamic imaging of median arcuate ligament syndrome utilizing low dose CT technology and a single contrast injection.

Survey of gadolinium-based contrast agent utilization among the members of the Society for Pediatric Radiology: a Quality and Safety Committee report

BackgroundGadolinium-based contrast agents (GBCAs) have been used for magnetic resonance (MR) imaging over the last three decades. Recent reports demonstrated gadolinium retention in patients’ brains following intravenous administration. Since gadolinium is a highly toxic heavy metal, there is a potential for adverse effects from prolonged retention or deposition, particularly in children. For this reason, the Society (SPR) for Pediatric Radiology Quality and Safety committee conducted a survey to evaluate the current status of GBCAs usage among pediatric radiologists.ObjectiveTo assess the usage of GBCAs among SPR members.Materials and methodsAn online 15-question survey was distributed to SPR members. Survey questions pertained to the type of GBCAs used, protocoling workflow, requirement of renal function or pregnancy tests, and various clinical indications for contrast-enhanced MRI examinations.ResultsA total of 163 survey responses were compiled (11.1% of survey invitations), the majority of these from academic institutions in the United States. Ninety-four percent reported that MR studies are always or usually protocoled by pediatric radiologists. The most common GBCA utilized by survey respondents were Eovist (60.7%), Ablavar (45.4%), Gadovist (38.7%), Magnevist (34.4%) and Dotarem (32.5%). For several clinical indications, survey responses regarding GBCA administration were concordant with American College of Radiology (ACR) Appropriateness Criteria, including seizures, headache and osteomyelitis. For other indications, including growth hormone deficiency and suspected vascular ring, survey responses revealed potential overutilization of GBCAs when compared to ACR recommendations.ConclusionSurvey results demonstrate that GBCAs are administered judiciously in children, yet there is an opportunity to improve their utilization with the goal of reducing potential future adverse effects.

Review of key concepts in magnetic resonance physics

MR physics can be a challenging subject for practicing pediatric radiologists. Although many excellent texts provide very comprehensive reviews of the field of MR physics at various levels of understanding, the authors of this paper explain several key concepts in MR physics that are germane to clinical practice in a non-rigorous but practical fashion. With the basic understanding of these key concepts, practicing pediatric radiologists can build on their knowledge of current clinical MR techniques and future advances in MR applications. Given the challenges of both the increased need for rapid imaging in non-sedated children and the rapid physiological cardiovascular and respiratory motion in pediatric patients, many advances in complex MR techniques are being applied to imaging these children. The key concepts are as follows: (1) structure of a pulse sequence, (2) k-space, (3) “trade-off triangle” and (4) fat suppression. This review is the first of five manuscripts in a minisymposium on pediatric MR. The authors’ goal for this review is to aid in understanding the MR techniques described in the subsequent manuscripts on brain imaging and body imaging in this minisymposium.

The Primary Physis

The primary physis is responsible for long bone growth in children and adolescents. Injury and physiologic or metabolic stress to the primary physis present unique radiologic findings that are important for radiologists to recognize and diagnose. Appreciation of the anatomy and histology of the primary physis forms the basis for understanding the imaging findings associated with pathologic conditions affecting the primary physis. Salter-Harris injuries, physeal bars, growth arrest lines, rickets, and focal periphyseal edema zones are common conditions with recognizable radiologic presentations. Proper diagnosis of these primary physeal conditions will aid in the treatment of affected pediatric patients.

Wrist MR imaging in children: Effect on clinical diagnosis and management

OBJECTIVES Evaluate the impact of wrist MRI in children on clinical diagnosis and management. MATERIALS AND METHODS Four year retrospective analysis including demographics, MRI diagnoses, and effect on diagnoses and management were determined. RESULTS 101 patients were included. Wrist MRI altered management in 86% (95% CI: 77-92%) and diagnosis in 46% (36-56%) of patients. MRI changed both diagnosis and management in 41% (31-51%), changed management only in 46% (35-56%), changed diagnosis only in 5% (2-12%), and had no change in diagnosis or management in 9% (95% CI: 4-17%). CONCLUSION Wrist MRI in children changes clinical diagnosis and management in a substantial proportion of cases.