Imaging of Scaphoid Fractures According to the New S3 Guidelines

Abstract

Up to 30 % of acute scaphoid fractures are missed in conventional radiography. CT and MRI should be early performed in the diagnostic workflow, when radiograms (dorsopalmar, lateral and Stecher’s views) are negative or inconclusive in fracture detection. Significance of CT is different from that of MRI: Sensitivity of CT imaging (85 to 95 %) is superior to conventional radiography (about 70 %), but inferior to MRI (almost 100 %). However, CT (specificity 95 to 100 %) is able to provide more detailed anatomic information of the fracture pattern when compared to MRI (specificity 80 to 90 %). Particularly, differentiation of bone contusion (“bone bruise”) and non-displaced fracture can be difficult in MRI. Thus, CT indication is not only given for fracture detection, but also for assessing the morphology in scaphoid fractures (localization, fragment dislocation, comminuted zones) and the fragment instability, too. MRI should be limited to equivocal trauma cases presenting pain in the snuff box, but with inconclusive CT findings. In CT and MRI of scaphoid fractures, image display must be aligned along the longitudinal extension of the scaphoid, either by acquiring or reformatting oblique-sagittal and oblique-coronal planes.

Key points

• Radiography can be limited to the dorsopalmar, lateral and Stecher’s views in scaphoid fractures.

• In CT and MR imaging, the dedicated anatomy of the scaphoid has to be covered with oblique-sagittal and oblique-coronal images.

• CT provides most detailed information of scaphoid fractures (localization, fragment dislocation and instability pattern). However, its capability in detecting non-displaced fractures is inferior to MRI.

• All scaphoid fractures are seen in MRI. But differentiation of bone contusion (bone bruise) and a non-displaced fracture can be crucial.

• This order is recommended in the diagnostic algorithm of scaphoid fractures: 1. radiography, 2. CT, and 3. MRI.

Citation Format:

• Schmitt R, Rosenthal H. Imaging of Scaphoid Fractures According to the New S3 Guidelines. Fortschr Röntgenstr 2016; 188: 459 – 469

Zusammenfassung

In der Projektionsradiografie werden bis zu 30 % der Skaphoidfrakturen übersehen. Deshalb sollten die Schnittbildverfahren der CT und MRT großzügig eingesetzt werden, wenn die Projektionsradiogramme (dorsopalmare, seitliche, Stecheraufnahmen) keinen oder einen unsicheren Frakturnachweis ergeben. Die Aussagemöglichkeiten der Schnittbildverfahren müssen differenziert betrachtet werden: Die CT weist mit einer Sensitivität zwischen 85 % und 95 % mehr Frakturen als das konventionelle Röntgen nach, jedoch weniger als die MRT (Sensitivität annähernd 100 %). Demgegenüber liefert die CT (Spezifität 95 – 100 %) bessere anatomische Informationen zum Frakturmuster und zur Fragmentdislokation im Vergleich zur MRT (Spezifität 80 – 90 %), bei der die Differenzierung einer Knochenkontusion („bone bruise“) gegenüber einer nicht dislozierten Fraktur schwierig sein kann. Neben dem Frakturnachweis ist die CT daher bei jeder Skaphoidfraktur zur Beurteilung der Morphologie (Frakturlokalisation, Fragmentdislokation, Trümmerzone) und der Stabilität indiziert. In unsicherer Situation sollte die MRT eingesetzt werden, wenn am symptomatischen Kahnbein mit der CT der Frakturnachweis nicht gelingt. Die Schnittführung muss sowohl am CT als auch am MRT parallel zur Längsachse des Kahnbeins mit schräg-sagittalen und schräg-koronalen Schichten ausgerichtet werden.

Key words

conventional radiography - CT - MR-imaging - trauma - scaphoid fracture

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