16-MDCT of the Posttraumatic Pediatric Elbow: Optimum Parameters and Associated Radiation Dose

Comparative dosimetry of radiography device, MSCT device and two CBCT devices in the elbow region

The aim of the study was to estimate and to compare effective doses in the elbow region resulting from four different x-ray imaging modalities. Absorbed organ doses were measured using 11 metal oxide field effect transistor (MOSFET) dosimeters that were placed in a custom-made anthropomorphic elbow RANDO phantom. Examinations were performed using Shimadzu FH-21 HR radiography device, Siemens Sensation Open 24-slice MSCT-device, NewTom 5G CBCT device, and Planmed Verity CBCT device, and the effective doses were calculated according to ICRP 103 recommendations. The effective dose for the conventional radiographic device was 1.5 µSv. The effective dose for the NewTom 5G CBCT ranged between 2.0 and 6.7 µSv, for the Planmed Verity CBCT device 2.6 µSv and for the Siemens Sensation MSCT device 37.4 µSv. Compared with conventional 2D radiography, this study demonstrated a 1.4-4.6 fold increase in effective dose for CBCT and 25-fold dose for standard MSCT protocols. When compared with 3D CBCT protocols, the study showed a 6-19 fold increase in effective dose using a standard MSCT protocol. CBCT devices offer a feasible low-dose alternative for elbow 3D imaging when compared to MSCT.

Current Concepts in the Treatment of Lateral Condyle Fractures in Children

Lateral condyle fractures of the humerus are the second most common fracture about the elbow in children. The injury typically occurs as a result of a varus- or valgus-applied force to the forearm with the elbow in extension. Plain radiographs are sufficient in making the diagnosis; however, an elbow arthrogram permits optimal visualization of the articular surface in minimally displaced fractures. Traditionally, nonsurgical management is indicated for fractures with ≤2 mm of displacement and a congruent articular surface. Closed reduction and percutaneous pinning is performed for fractures with >2 mm of displacement with an intact cartilaginous hinge at the articular surface. Open reduction and internal fixation is often necessary for fractures with ≥4 mm of displacement or if there is articular incongruity. Complications include malunion, delayed presentation, fishtail deformity, lateral spurring, and growth arrest. Evolving management concepts include relative indications for surgical management, the optimal pin configuration, and the use of cannulated screw and bioresorbable fixation.

Posteromedial elbow dislocation with lateral humeral condylar fracture in children: Three case reports and a literature review

RATIONALE

Posteromedial dislocations of the elbow with lateral humeral condylar fractures (LCFs) are uncommon, and only isolated cases have been reported in the English-language literature. Because of the complex radiolucent cartilaginous structures and late-appearing ossification centers, radiological diagnosis of elbow dislocations with LCF in children is challenging.

PATIENT CONCERNS

We report three children with posteromedial elbow dislocation: two patients with Milch type I and one patient with Milch type II LCF.

DIAGNOSES

In our report, radiographs showed only a small bone fragment, and arthrography or computed tomography were helpful diagnostic aids in cases 1 and 3. In contrast, the patient in case 2 was initially misdiagnosed as having an epiphyseal separation of the distal humerus, and open reduction and internal fixation through the posterior approach revealed Milch type II LCF.

INTERVENTIONS

In case 1 and 3, Milch type I LCFs, open reduction and internal fixation was performed through the posterolateral approach. On the other hand, in case 2, Milch type II LCF, open reduction and internal fixation was performed through the posterior approach.

OUTCOMES

Poor reduction of Milch type I LCFs resulted in incongruity of the articular surface and poor cosmetic results in two patients. In case 2, Milch type II LCF, plain radiographs showed adequate healing without elbow deformity and the clinical result was excellent.

LESSONS

Because LCFs are intra-articular fractures, anatomical reduction is crucial for satisfactory outcomes. We promote awareness of this injury, especially posteromedial dislocation with Milch type I LCF. Preoperative evaluation is helpful for achieving satisfactory outcomes, and open reduction and internal fixation through an anterolateral approach might be most appropriate for Milch type I LCFs.

Diagnosis, management and complications of distal humerus lateral condyle fractures in children

We review the diagnosis, evaluation and management of paediatric lateral condylar fractures. The complications of these fractures are also discussed, including the management of fracture non-union.

Dose reduction and compliance with pediatric CT protocols adapted to patient size, clinical indication, and number of prior studies

PURPOSE

To assess compliance and resultant radiation dose reduction with new pediatric chest and abdominal computed tomographic (CT) protocols based on patient weight, clinical indication, number of prior CT studies, and automatic exposure control.

MATERIALS AND METHODS

The study was institutional review board approved and HIPAA compliant. Informed consent was waived. The new pediatric CT protocols, which were organized into six color zones based on clinical indications and number of prior CT examinations in a given patient, were retrospectively assessed. Scanning parameters were adjusted on the basis of patient weight. For gradual dose reduction, pediatric CT (n = 692) examinations were performed in three phases of incremental stepwise dose reduction during a 17-month period. There were 245 male patients and 193 female patients (mean age, 12.6 years). Two radiologists independently reviewed CT images for image quality. Data were analyzed by using multivariate analysis of variance.

RESULTS

Compliance with the new protocols in the early stage of implementation (chest CT, 58.9%; abdominal CT, 65.2%) was lower than in the later stage (chest CT, 88%; abdominal CT, 82%) (P < .001). For chest CT, there was 52.6% (9.1 vs 19.2 mGy) to 85.4% (2.8 vs 19.2 mGy) dose reduction in the early stage of implementation and 73.5% (4.9 vs 18.5 mGy) to 83.2% (3.1 vs 18.5 mGy) dose reduction in the later stages compared with dose at noncompliant examinations (P < .001); there was no loss of clinically relevant image quality. For abdominal CT, there was 34.3% (9.0 vs 13.7 mGy) to 80.2% (2.7 vs 13.7 mGy) dose reduction in the early stage of implementation and 62.4% (6.5 vs 17.3) to 83.8% (2.8 vs 17.3 mGy) dose reduction in the later stage (P < .001).

CONCLUSION

Substantial dose reduction and high compliance can be obtained with pediatric CT protocols tailored to clinical indications, patient weight, and number of prior studies.

Price of Isotropy in Multidetector CT

Recent advances in multidetector computed tomography (CT) have made isotropic data acquisition feasible for nearly every application. The benefits of routine use of isotropic data for image display and interpretation have been described in the literature and at educational conferences. However, there is usually a trade-off in the form of an increased radiation dose to the patient. The parameters that affect the radiation dose vary considerably in accordance with the CT scanner design, and those variations determine the cost in dose increase relative to the voxel size. The detector configuration and beam collimation (narrow or wide) used for a particular acquisition also affect the voxel size and the relationship between spatial resolution and the radiation dose. By closely comparing the quality of multidetector CT images obtained with different detector configurations on scanners with four, 16, 40, and 64 channels and the estimated radiation exposure incurred with each option, radiologists may achieve an understanding of the relationship between radiation dose and voxel size. This understanding, in turn, may help balance the need for diagnostic image quality against the concern for patient safety.

Multidetector computed tomography of pediatric lateral condylar fractures

OBJECTIVE

The objective of this study was to compare lateral condylar fracture characterization using radiographs and multidetector computed tomography (MDCT) of the elbow and to evaluate outcomes in a group of children managed based on MDCT findings.

METHODS

Unenhanced MDCT of the elbow with sagittal and coronal reformations was prospectively performed without sedation in 10 children between 1 and 16 years of age with lateral condylar fractures identified on frontal and lateral radiographs of the elbow. Two blinded readers reviewed all radiographs and MDCT images independently and in consensus. For the radiographs and MDCT images, readers graded the displacement of the lateral condyle fracture fragment and classified the fractures according to the Milch classification. Articular and epiphyseal cartilage integrity was assessed on MDCT. Patients were managed based on the consensus interpretation of the MDCT study. The frequency of interobserver agreement, discordant grading of fracture displacement and fracture classification between radiographs and MDCT images, and altered management based on the MDCT findings were determined.

RESULTS

Individual readers agreed on fracture displacement in 9 patients (90%) on radiographs and in all 10 patients (100%) on MDCT. Individual readers agreed on fracture classification in 4 patients (40%) on radiographs and in 9 patients (90%) on MDCT. In 4 patients (40%), grading of fracture displacement differed between the consensus interpretation of the radiographs and MDCT images. In 6 patients (60%), fracture classification differed between the consensus interpretation of the radiographs and MDCT images. All 3 patients with fracture displacement greater than 5 mm and 1 patient with fracture displacement between 2 and 5 mm demonstrated disruption of the articular and epiphyseal cartilage on MDCT. Two patients (20%) with fracture displacement near the surgical threshold of 2 mm had altered management based on the MDCT findings. All patients progressed to complete fracture healing, with no delayed displacement or other complications.

CONCLUSIONS

Multidetector computed tomography is a highly reproducible means of characterizing pediatric lateral condylar fractures and frequently demonstrates disruption of the epiphyseal and articular cartilage in patients with fracture displacement greater than 2 mm. The findings of MDCT may lead to altered treatment in patients with fracture displacement near the surgical threshold of 2 mm.