BACKGROUNDBenign bone tumors are common incidental findings in the pediatric population during radiographic evaluation. Counseling these patients requires reassurance and raises questions about the natural history of these tumors over time. The purpose of this study was to estimate the prevalence and observe the behavior of benign childhood bone tumors in an asymptomatic population.METHODSA historical, longitudinal radiographic collection of healthy children was reviewed, which included comprehensive left-sided radiographs of the extremities at yearly intervals. In this study, 262 subjects with 25,555 radiographs were screened for benign bone tumors at a median age of 8 years (range, 0 to 18 years). All potential tumors were reviewed by a multidisciplinary panel, which confirmed the radiographic diagnosis of each lesion, the age at which the lesion first appeared, and the age at which it had resolved. Prevalence rates were calculated using the number of distinct subjects available for each radiographic location and age.RESULTSThirty-five tumors were identified in 33 subjects, including 19 nonossifying fibromas, 8 enostoses, 6 osteochondromas, and 2 enchondromas. The prevalence rate for all tumors combined increased with age and was 18.9% overall. The overall prevalence rates for specific tumor types were 7.5% for nonossifying fibromas, 5.2% for enostoses, 4.5% for osteochondromas, and 1.8% for enchondromas. Nonossifying fibromas demonstrated a bimodal distribution of prevalence, with a peak at 5 years (10.8%) and another after skeletal maturity (13.3%). The median age at the first appearance for all tumors combined was 9 years (range, 2 to 15 years), but varied by tumor type. Nonossifying fibromas often resolved (7 [37%] of 19), with further resolution possible beyond the last available radiograph. Enostoses, osteochondromas, and enchondromas persisted until the last available radiographs in all subjects.CONCLUSIONSThe prevalence of benign childhood bone tumors of the extremities was 18.9% in a historical asymptomatic population. Longitudinal radiographs allowed observation of the timing of the first appearance and the potential for resolution for each tumor type. These findings provide unique evidence to answer many commonly encountered questions when counseling patients and their families on benign bone tumors.LEVEL OF EVIDENCEPrognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Juxtacortical or surface tumors of bone are neoplasms arising from or just outside the cortex, and are composed of different histologic types. Although the imaging appearances of these lesions have similarities to their intramedullary counterparts, their location alters their radiographic and MR characteristics, creating difficulties in diagnosis. Meanwhile, several non-neoplastic lesions, such as stress reaction/stress fracture and indolent infectious processes, compound the differential diagnosis. Neoplastic juxtacortical lesions of bone have been classified into five categories: cartilaginous, fibrous, lipomatous, osseous, and metastatic tumors. Our goal in part two of this review is to illustrate the characteristic radiographic, CT and MR imaging features of various juxtacortical neoplasms, including pathognomonic imaging findings that can aid in diagnosis, and to develop an appropriate differential diagnosis for surface lesions based on imaging characteristics, lesion location and patient age.

Purpose The purpose of this study was to investigate how the use of multi-modal rigid image registration integrated within a standard picture archiving and communication system affects the efficiency of a radiologist while performing routine interpretations of cases including prior examinations. Methods Six radiologists were recruited to read a set of cases (either 16 neuroradiology or 14 musculoskeletal cases) during two crossover reading sessions. Each radiologist read each case twice, one time with synchronized navigation, which enables spatial synchronization across examinations from different study dates, and one time without. Efficiency was evaluated based upon time to read a case and amount of scrolling while browsing a case using Wilcoxon signed rank test. Results Significant improvements in efficiency were found considering either all radiologists simultaneously, the two sections separately and the majority of individual radiologists for time to read and for amount of scrolling. The relative improvement for each individual radiologist ranged from 4 to 32% for time to read and from 14 to 38% for amount of scrolling. Conclusion Image registration providing synchronized navigation across examinations from different study dates provides a tool that enables radiologists to work more efficiently while reading cases with one or more prior examinations.

Magnetic resonance imaging (MRI) with direct intraarticular injection of contrast (direct MR arthrography) has been employed for the diagnosis of labral and cartilaginous lesions. Several studies have shown direct MR arthrography is superior to conventional non-contrast MR imaging for detection of cartilage and labral pathologies. Magee (1) found 3.0-T MR arthrography is more sensitive than conventional MR for detection of acetabular cartilaginous defects. However, there are several disadvantages with direct MR arthrography, including its invasive nature and inherent radiation required for image guided contrast injection (2). Indirect MR arthrography has been introduced as an alternative that provides high quality and arthrogram-like images of the articulation by enhancing the highly vascular synovial membranes and by secondary arthrographic effect with contrast excreted into the synovial space. It does not require intraarticular contrast injection, thus avoids radiation exposure, the invasive nature, and the potential additional scheduling coordination problems. Indirect MR arthrogram is performed after intravenous (IV) gadolinium injection and variable periods of delay and/or exercise to allow contrast to passively diffuse into the joint thereby simulating the arthographic effect. In a typical protocol, patients are instructed to walk on a treadmill at the speed of 2.5-3 miles/hour for 15 minutes before image acquisition. Standard image analysis is performed by dividing the femoral and acetabular cartilage and labral zones into 4 quadrants (3): anteroinferior (AI) 6-9 o’clock; anterosuperior (AS) 9-12 o’clock; posterosuperior (PS) 12-3 o’clock; and posteroinferior (PI) 3-6 o’clock. Only a few studies have tested the value of indirect MR arthrogram in the evaluation of femoroacetabular labrum and cartilage. Zlatkin et al (4) found conventional MRI detects only 85% of arthroscopically detected labral tears, whereas 100% of tears are identified by indirect MR arthrography. Moreover, 70% of labral tears identified on conventional MRI are better delineated by indirect MR arthrography. However, it was concluded that detection and characterisation of cartilage abnormalities do not improve with the use of indirect MR arthrography over conventional MRI. Of note, this study was limited, as it was performed on a 1.5-T magnet and on a limited number of 14 patients. In a more recent study by Petchprapa et al (3), indirect MR arthrography on a 3-T magnet was employed to evaluate hip cartilage and labral pathology, using arthroscopy as the reference standard. Sensitivity, specificity, accuracy, negativeand positive-predictive values of indirect MR arthrography for labral lesion were 98%, 99%, 99%, 99% and 98%, respectively. The respective values for acetabular cartilage lesion were 69%, 98%, 89%, 87% and 95% and for femoral cartilage lesion 69%, 95%, 93% and 39%. It was concluded that indirect MR arthrography is a viable alternative to direct MR arthrography. However, this study had no head-to-head comparison with conventional MRI. Regarding the advantages of indirect MR arthrogram over direct MR arthrogram, this imaging approach warrants further consideration by the radiology community. Future studies with head-to-head comparison of conventional imaging as well as direct and indirect MR arthrography using the gold standard of arthroscopy are needed to evaluate the potential for substitution of direct hip arthrogram with its noninvasive counterpart.

Mucolipidosis type II (I-Cell disease) is a rare autosomal recessive lysosomal disorder, resulting from functional deficiency of lysosomal enzymes due to an impaired targeting of the enzymes to lysosomes, which leads to an abnormal cell architecture and the overflow of lysosomal enzymes into the body fluids. The life expectancy of the patients is poor, with multisystem deterioration leading to death in early childhood. According to the available reports, patients with I-cell disease do not survive beyond the first decade of life. Here, we describe and illustrate various radiological-musculoskeletal manifestations of a rare case of mucolipidosis II who has been a survivor up to now, 20 years old. The course of her disease has been complicated by early severe visual compromise due to optic nerve swelling, hearing loss and mitral valve regurgitation/stenosis, bilateral carpal tunnel, and severe growth impairment. Our case demonstrates several skeletal features of dysostosis multiplex. At the age of 20, she is wheelchair bound and her medical course is complicated by recurrent pneumonia, treated with multiple hospitalizations, antibiotics, and BiPAP. She is on outpatient palliative care, Do Not Resuscitate/Do Not Intubate (DNR/DNI) status.

Radiofrequency ablation technique for treatment of OO including ablation time and temperature vary greatly between and within reported studies. This study evaluates the immediate and long-term efficacy and complication rate of a two sequential RFA technique for OO.

Background: The majority of rim recession for femoroacetabular impingement (FAI) is performed anteriorly and has traditionally been assessed by the lateral center-edge (CE) angle, which correlates most closely with lateral coverage. The radiographic false-profile view permits measurement of anterior coverage via the anterior CE angle and more closely correlates with anterior coverage. Purpose: To answer the following questions: (1) How does incremental anterior rim recession change lateral and anterior CE angles? and (2) Can these changes be predicted by a formula? Study Design: Descriptive laboratory study. Methods: Twelve cadaveric hips were dissected free of soft tissue to expose the anterior acetabular rim. Incremental resections of 2.5 mm (range, 0-10 mm) were performed from the 12- to 3-o’clock position using a Dremel rotary tool. Anteroposterior hip and false-profile radiographs were obtained at each interval using a fluoroscopic C-arm. The lateral and anterior CE angles were measured by 3 orthopaedic surgeons. Results: The average preresection lateral CE angle was 35.1°, and the mean decrease in lateral CE angle from 0 to 10 mm was 9.9°; the average preresection anterior CE angle was 38.4° and the mean decrease in anterior CE angle from 0 to 10 mm was 18.2°. The anterior CE angle decreased by a factor of 1.9 when compared with the lateral CE angle ( P = 2 × 10−7). The lateral CE angle decreased by approximately 1° (1.0°) per millimeter of rim recessed. The anterior CE angle decreased by approximately 2° (1.8°) per millimeter of rim recessed. Conclusion: The lateral CE angle should not be extrapolated to reflect anterior acetabular coverage. The anterior CE angle is a superior marker and predictably decreases with rim recession at double the rate of the lateral CE angle. Clinical Relevance: The false-profile view is recommended in the perioperative workup for all patients undergoing arthroscopic treatment of pincer impingement.

Contrast enhancement of the vertebral body marrow may be seen secondary to collateral venous blood flow via the vertebral venous plexus in the setting of superior vena cava obstruction. We report a 48-year-old woman presenting with bilateral brachiocephalic vein obstruction and multilevel thoracic spine hyperdensities as seen on venous-phase CT angiography (CTA), initially concerning for sclerotic neoplastic lesions. A contrast-enhanced CT of the neck obtained 1 day prior to the chest CTA did not demonstrate any osseous abnormality, and inspection of the chest CTA demonstrated filling of perivertebral venous collateral vessels. The abnormal vertebral body enhancement was therefore feltsecondary to retrograde collateral venous flow via the basivertebral venous plexus in the setting of functional SVC obstruction. Vertebral body enhancement should be considered in patients with thoracic central venous obstruction when enhancement or apparent sclerosis of the vertebral bodies is seen on CTA.

Diffusion-weighted imaging (DWI) is an established diagnostic tool with regards to the central nervous system (CNS) and research into its application in the musculoskeletal system has been growing. It has been shown that DWI has utility in differentiating vertebral compression fractures from malignant ones, assessing partial and complete tears of the anterior cruciate ligament (ACL), monitoring tumor response to therapy, and characterization of soft-tissue and bone tumors. DWI is however less useful in differentiating malignant vs. infectious processes. As of yet, no definitive qualitative or quantitative properties have been established due to reasons ranging from variability in acquisition protocols to overlapping imaging characteristics. Even with these limitations, DWI can still provide clinically useful information, increasing diagnostic accuracy and improving patient management when magnetic resonance imaging (MRI) findings are inconclusive. The purpose of this article is to summarize recent research into DWI applications in the musculoskeletal system.