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PURPOSE: To compare the delivered radiation dose between a low-dose hip CT (Computed Tomography) scan protocol and traditional hip CT scan protocols (referred to as: traditional CT). METHODS: This was a retrospective comparative cohort study. A group of patients who underwent hip preservation surgery (including arthroscopy, surgical hip dislocation, or periacetabular osteotomy procedures) at our institution between 2016-2017 were identified. Patients were excluded if they had a BMI>35 kg/m(2), previous surgery, or absence of a radiation dose report. The low-dose group included patients undergoing hip CT at our institution utilizing a standardized protocol of 100 kVp, 100 mAs and limited scanning field. The traditional CT group included patients who had hip CT scans performed at outside institutions. The total effective dose (E(hip)), effective dose per millimeter-body-length-scanned (E(mm)), and the patients’ age, BMI were compared by univariate analysis. The correlation of E(hip) to BMI was assessed. RESULTS: Forty-one consecutive patients were included in the low-dose group, and 18 consecutive patients were included in the traditional CT group. Low-dose CT resulted in 90% reduction in radiation exposure compared to traditional CT (E(hip)=0.97 ± 0.28 vs. 9.68 ± 6.67mSv, p

Juvenile localized scleroderma comprises a group of autoimmune conditions often characterized clinically by an area of skin hardening. In addition to superficial changes in the skin and subcutaneous tissues, juvenile localized scleroderma may involve the deep soft tissues, bones and joints, possibly resulting in functional impairment and pain in addition to cosmetic changes. There is literature documenting the spectrum of findings for deep involvement of localized scleroderma (fascia, muscles, tendons, bones and joints) in adults, but there is limited literature for the condition in children. We aimed to document the spectrum of musculoskeletal magnetic resonance imaging (MRI) findings of both superficial and deep juvenile localized scleroderma involvement in children and to evaluate the utility of various MRI sequences for detecting those findings. Two radiologists retrospectively evaluated 20 MRI studies of the extremities in 14 children with juvenile localized scleroderma. Each imaging sequence was also given a subjective score of 0 (not useful), 1 (somewhat useful) or 2 (most useful for detecting the findings). Deep tissue involvement was detected in 65% of the imaged extremities. Fascial thickening and enhancement were seen in 50% of imaged extremities. Axial T1, axial T1 fat-suppressed (FS) contrast-enhanced and axial fluid-sensitive sequences were rated most useful. Fascial thickening and enhancement were the most commonly encountered deep tissue findings in extremity MRIs of children with juvenile localized scleroderma. Because abnormalities of the skin, subcutaneous tissues and fascia tend to run longitudinally in an affected limb, axial T1, axial fluid-sensitive and axial T1-FS contrast-enhanced sequences should be included in the imaging protocol.

The diagnosis of soft-tissue masses in children can be difficult because of the frequently nonspecific clinical and imaging characteristics of these lesions. However key findings on imaging can aid in diagnosis. The identification of macroscopic fat within a soft-tissue mass narrows the differential diagnosis considerably and suggests a high likelihood of a benign etiology in children. Fat can be difficult to detect with sonography because of the variable appearance of fat using this modality. Fat is easier to recognize using MRI, particularly with the aid of fat-suppression techniques. Although a large portion of fat-containing masses in children are adipocytic tumors, a variety of other tumors and mass-like conditions that contain fat should be considered by the radiologist confronted with a fat-containing mass in a child. In this article we review the sonographic and MRI findings in the most relevant fat-containing soft-tissue masses in the pediatric age group, including adipocytic tumors (lipoma, angiolipoma, lipomatosis, lipoblastoma, lipomatosis of nerve, and liposarcoma); fibroblastic/myofibroblastic tumors (fibrous hamartoma of infancy and lipofibromatosis); vascular anomalies (involuting hemangioma, intramuscular capillary hemangioma, phosphate and tensin homologue (PTEN) hamartoma of soft tissue, fibro-adipose vascular anomaly), and other miscellaneous entities, such as fat necrosis and epigastric hernia.

Post-traumatic subperiosteal hematoma of the iliac bone may present insidiously without external evidence of bleeding or go undetected in the acute setting. In some cases, the patient may come to medical attention due to femoral nerve palsy rather than hip or groin pain. In this report, we describe a case of femoral nerve palsy caused by acute post-traumatic subperiosteal hematoma of the iliac bone using MRI to highlight the subperiosteal location. Anatomy of the femoral nerve is also discussed.

Unsuccessful lumbar puncture (LP) attempts may lead to epidural hematoma (EH) formation within the spinal canal at the site of needle insertion, which can affect subsequent attempts. We aimed to determine the rate of EH formation after infant LP using bedside ultrasound (US). Furthermore, we aimed to correlate both perceived trauma during LP and cerebral spinal fluid (CSF) red blood cell (RBC) counts with EH formation.We enrolled infants younger than 6 months who underwent LP in the emergency department. The primary investigator performed a bedside US of the lumbar spine, which was reviewed and interpreted by a pediatric radiologist. Treating clinicians performed the procedure and were asked to classify each attempt as "traumatic" or "atraumatic." Cerebral spinal fluid RBC counts were recorded.Thirty-one percent of patients had evidence of post-LP EH, 17% of which completely effaced the thecal sac. Forty percent of patients with at least 1 traumatic attempt had evidence of EH, whereas 25% without reported trauma showed EH (P = 0.17). Patients with EH had a median CSF RBC cell count of 186 cells/mm (range, 0-239,525) compared with 5 cells/mm (range, 0-3429) in patients without evidence of EH (P = 0.008).Epidural hematomas are frequent after LP. Perceived trauma during LP and CSF RBC counts are not adequate predictors of EH formation. Point-of-care US may be a valuable adjunct to help guide subsequent needle insertions sites for repeat attempts after an unsuccessful LP.

BACKGROUND Unsuccessful lumbar puncture (LP) attempts may lead to epidural hematoma (EH) formation within the spinal canal at the site of needle insertion, which can affect subsequent attempts. We aimed to determine the rate of EH formation after infant LP using bedside ultrasound (US). Furthermore, we aimed to correlate both perceived trauma during LP and cerebral spinal fluid (CSF) red blood cell (RBC) counts with EH formation. METHODS We enrolled infants younger than 6 months who underwent LP in the emergency department. The primary investigator performed a bedside US of the lumbar spine, which was reviewed and interpreted by a pediatric radiologist. Treating clinicians performed the procedure and were asked to classify each attempt as "traumatic" or "atraumatic." Cerebral spinal fluid RBC counts were recorded. RESULTS Thirty-one percent of patients had evidence of post-LP EH, 17% of which completely effaced the thecal sac. Forty percent of patients with at least 1 traumatic attempt had evidence of EH, whereas 25% without reported trauma showed EH (P = 0.17). Patients with EH had a median CSF RBC cell count of 186 cells/mm (range, 0-239,525) compared with 5 cells/mm (range, 0-3429) in patients without evidence of EH (P = 0.008). CONCLUSIONS Epidural hematomas are frequent after LP. Perceived trauma during LP and CSF RBC counts are not adequate predictors of EH formation. Point-of-care US may be a valuable adjunct to help guide subsequent needle insertions sites for repeat attempts after an unsuccessful LP.

Acute appendicitis, especially if perforated at presentation, is often complicated by postoperative abscess formation. The detection of a postoperative abscess relies primarily on imaging. This has traditionally been done with contrast-enhanced computed tomography. Non-contrast magnetic resonance imaging (MRI) has the potential to accurately detect intra-abdominal abscesses, especially with the use of diffusion-weighted imaging (DWI). To evaluate our single-center experience with a rapid non-contrast MRI protocol evaluating post-appendectomy abscesses in children with persistent postsurgical symptoms. In this retrospective, institutional review board-approved study, all patients underwent a clinically indicated non-contrast 1.5- or 3-Tesla abdomen/pelvis MRI consisting of single-shot fast spin echo, inversion recovery and DWI sequences. All MRI studies were reviewed by two blinded pediatric radiologists to identify the presence of a drainable fluid collection. Each fluid collection was further characterized as accessible or not accessible for percutaneous or transrectal drainage. Imaging findings were compared to clinical outcome. Seven of the 15 patients had a clinically significant fluid collection, and 5 of these patients were treated with percutaneous drain placement or exploratory laparotomy. The other patients had a phlegmon or a clinically insignificant fluid collection and were discharged home within 48 h. Rapid non-contrast MRI utilizing fluid-sensitive and DWI sequences can be used to identify drainable fluid collections in post-appendectomy patients. This protocol can be used to triage patients between conservative management vs. abscess drainage without oral/intravenous contrast or exposure to ionizing radiation.

Objectives: Lateralization of the tibial tubercle plays a significant role in the pathophysiology of patellar instability and is most often assessed by the tibial tubercle to trochlear groove distance (TT-TG) measured on CT or MRI with the knee in extension. However, tracking of the patella in 30 to 45 degrees of flexion has been suggested to be of greater clinical significance. Merchant radiographs can demonstrate the position of the tibial tubercle relative to the trochlear groove in this range of flexion and thus may serve as a valuable tool in the assessment of patellar tracking. The purpose of the current study was (1) to validate radiographic assessment of the merchant view TT-TG and (2) to determine the correlation with MRI-based measurements. Methods: To validate Merchant TT-TG as a marker of the position of the tibial tubercle, 41 patients between the ages of 10-18 had standardized Merchant radiographs in 45 degrees flexion yielding imaging of 82 knees. Lead markers were placed upon the skin centered over the tibial tubercle based on palpation. Radiographs were collected and analyzed. The TT-TG was measured as the distance between lines centered over the deepest point of the trochlear groove and the center of the tibial tubercle and perpendicular to the anterior condylar axis. In order to correlate Merchant TT-TG to MRI TT-TG, 16 additional patients were added to reach a total of 30 patients with a Merchant radiograph and MRI, as power calculation determined 29 knees needed to detect a Pearson correlation coefficient (PCC) of .500. There was excellent interobserver reliability between two readers for Merchant TT-TG with and without use of a radiographic marker (ICC = .975 and .923 respectively). Results: The tibial tubercle could be identified on Merchant radiograph in 67 images (81.7%). Merchant TT-TG measured with use of a marker was very strongly correlated measurement based on bony landmarks alone (PCC = .848). The Merchant TT-TG measured with bony landmarks alone was strongly correlated to MRI TT-TG (PCC = .602). The strength of this correlation was increased by standardizing TT-TG by patellar width (PCC = .710). MRI TT-TG was increased in patients with patellar instability at 13.9 mm compared to 10.5 mm (p Conclusion: Standardized Merchant radiographs without radiographic markers allow for assessment of TT-TG in the majority of patients. Merchant TT-TG strongly correlates with MRI TT-TG but measured 5-8 mm smaller than MRI TT-TG.

Objectives: Abnormal patellofemoral tracking has been implicated in patellar instability and can be influenced by the bony anatomy and alignment of the femoral trochlea, patella, and tibial tubercle. Tibiofemoral joint rotation has been recently suggested to play a role in patellofemoral kinematics but there has been little investigation of its contribution to patellar instability, including in pediatric and adolescent patients. Methods: A retrospective case-control design was utilized. 30 patients aged 9-18 with a prior patellar dislocation and an MRI of the involved knee were included. Cases were matched for age and gender with controls without patellar instability. Patients with ACL tears, tibial eminence or tubercle fractures, or prior surgery in the involved extremity were excluded. There was no difference in gender, age, height, but BMI was higher in the case group. MRI images taken with knee in extension were analyzed. Tibial tubercle-trochlear groove (TT-TG), tibial tubercle-posterior cruciate ligament (TT-PCL), and tibiofemoral rotation were measured. All measurements were performed by a single reader with excellent intra and interobserver reliability for tibiofemoral rotation (ICC-intra > .954 and ICC-inter > .905) demonstrated in a subset of patients. Results: The TT-TG was increased in patients with patellar instability at 16.3 mm compared to 10.9 mm in controls (p 5° external rotation versus only 3/41 controls (7.3%). There was a strong correlation between TT-TG and tibiofemoral rotation (PCC = 0.776) and a moderate correlation between TT-TG and TT-PCL (PCC = .661). There was only a weak correlation between tibiofemoral rotation and TT-PCL. Conclusion: Increased tibiofemoral rotation is present in patients with patellar instability and may play a role in the pathophysiology of patellar instability. Increased tibiofemoral rotation can lead to an increased TT-TG even when TT-PCL is normal.

Whole-body MR imaging is being increasingly used in children to evaluate the extent of various oncologic and non-oncologic entities. The lack of exposure to ionizing radiation, excellent soft-tissue contrast (even without the use of contrast agents), and functional imaging capabilities make it especially suitable for screening and surveillance in the pediatric population. Technical developments such as moving table platforms, multi-channel/multi-element surface coils, and parallel imaging allow imaging of the entire body with multiple sequences in a reasonable 30- to 40-min time frame, which has facilitated its acceptance in routine clinical practice. The initial investigations in whole-body MR imaging were primarily focused on oncologic applications such as tumor screening and staging. The exquisite sensitivity of fluid-sensitive MR sequences to many different types of pathology has led to new applications of whole-body MR imaging in evaluation of multifocal rheumatologic conditions. Availability of blood pool contrast agents has allowed whole-body MR angiographic imaging of vascular malformations, vasculitides and vasculopathies. Whole-body MRI is being applied for delineating the extent and distribution of systemic and multifocal diseases, establishing diagnoses, assessing treatment response, and surveillance imaging. This article reviews the technique and clinical applications of whole-body MR imaging in children.

During a study to determine if any genetic linkage existed between the chicken mutations pirouette and naked neck, it was found that when both traits are expressed simultaneously in an individual, an “automutilation” condition can be created in some cases. The tremulous head movements of naked neck-pirouette chicks cause scraping of the skin on the neck against the egg shell during hatching, resulting in lacerations of the neck in varying degrees. Because of this potential for injury, it is suggested that matings between carriers of tremulous neurological disorders and carriers of mutations that result in lack of down cover be avoided whenever possible.