Digital Tomography for Detection of Acute Occult Scaphoid Fractures

Diagnostic Performance and Advanced Imaging Reduction With Digital Tomosynthesis in Scaphoid Fracture Management

BACKGROUND

Management of scaphoid fractures often requires advanced imaging to achieve accurate diagnoses and appropriate treatment. Digital tomosynthesis (DTS) is a cross-sectional imaging modality that may be used to substitute magnetic resonance imaging or computed tomographic scans. The purpose of this study is to: (1) determine the diagnostic accuracy of DTS in occult scaphoid fractures; and (2) report on the reduction of other advanced imaging when using DTS.

METHODS

From May 2014 to October 2017, the charts of all patients who underwent scaphoid tomogram were retrospectively reviewed. The diagnostic accuracy of DTS for occult fracture was compared with 2-week follow-up plain films. To measure the reduction in utilization of advanced imaging, it was determined whether DTS eliminated the need for advanced imaging by providing adequate information regarding the clinical question.

RESULTS

A total of 78 patients underwent scaphoid tomography in this time frame: 39 for occult fracture, 33 for fracture union, 5 for fracture morphology, and 1 for hardware positioning. For the detection of occult fracture, DTS had a sensitivity of 100%, specificity of 83%, positive predictive value of 64%, and negative predictive value of 100%. Advanced imaging was not used in 35 of the remaining 39 patients based on the results obtained by DTS. In patients who did receive advanced imaging, 83% of tomograms provided conclusive diagnostic information.

CONCLUSIONS

Digital tomosynthesis increases the diagnostic sensitivity of occult scaphoid fractures, reducing unnecessary immobilization and advanced imaging. Digital tomosynthesis provides clinical detail beyond plain film, which reduces the need to obtain advanced imaging when assessing union, fracture pattern, and hardware placement.

Diagnosis of Suspected Scaphoid Fractures

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Suspected scaphoid fractures are a diagnostic and therapeutic challenge despite the advances in knowledge regarding these injuries and imaging techniques. The risks and restrictions of routine immobilization as well as the restriction of activities in a young and active population must be weighed against the risks of nonunion that are associated with a missed fracture.

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The prevalence of true fractures among suspected fractures is low. This greatly reduces the statistical probability that a positive diagnostic test will correspond with a true fracture, reducing the positive predictive value of an investigation.

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There is no consensus reference standard for a true fracture; therefore, alternative statistical methods for calculating sensitivity, specificity, and positive and negative predictive values are required.

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Clinical prediction rules that incorporate a set of demographic and clinical factors may allow stratification of secondary imaging, which, in turn, could increase the pretest probability of a scaphoid fracture and improve the diagnostic performance of the sophisticated radiographic investigations that are available.

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Machine-learning-derived probability calculators may augment risk stratification and can improve through retraining, although these theoretical benefits need further prospective evaluation.

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Convolutional neural networks (CNNs) are a form of artificial intelligence that have demonstrated great promise in the recognition of scaphoid fractures on radiographs. However, in the more challenging diagnostic scenario of a suspected or so-called "clinical" scaphoid fracture, CNNs have not yet proven superior to a diagnosis that has been made by an experienced surgeon.

Digital tomography is an effective investigation for sternoclavicular joint pathology

OBJECTIVE

Plain radiographs of the sternoclavicular joint (SCJ) are difficult to interpret, and a CT or MRI scan is the usual investigation of choice. At our hospital, we use digital SCJ tomograms as our first-line investigation for all SCJ pathologies. We wanted to ascertain whether this is a safe and appropriate first-line imaging investigation.

MATERIALS AND METHODS

We retrospectively reviewed every patient who had undergone an SCJ digital tomogram (DT) over a 4-year period. We cross-referenced each patient with their records to assess the reason for referral, result, requirement for further investigation, diagnosis and management.

RESULTS

We identified 132 SCJ tomograms over the study period. Twelve patients were referred from other hospitals with pre-existing imaging and were excluded. The reasons for radiological investigation in the remaining 120 patients were pain/lump without trauma (54.2%), pain/lump with trauma (30.8%) and post-operative review (15%). Of the 102 patients who had DT as their initial investigation, the most common diagnoses identified included osteoarthritis, normal SCJ, fracture and dislocation among others. Only 18 (17.6%) of these patients required further investigation with CT and/or MRI.

CONCLUSION

Our study is the first to assess digital tomography in SCJ pathology. We have shown that digital tomograms are an accurate and economically beneficial investigation for SCJ pathology and propose that it should be used as a first-line imaging investigation.