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1. The thoracic CT findings are diagnostic of arteriovenous malformation

The thoracic CT findings are diagnostic of arteriovenous malformation. Establishing this diagnosis at thoracic CT requires demonstrating a circumscribed, often peripheral, nodule or mass associated with one or more enlarged supplying arteries and one or more draining veins; the diagnosis of an arteriovenous malformation is a morphological one. While demonstrating enhancement of the nodule, or nidus, provides reinforcing evidence of the presence of an arteriovenous malformation, it is not required for diagnosis. In some cases, the nidus may be thrombosed, in which case enhancement of the nidus may not be apparent, but the diagnosis may nevertheless be established through appreciation of the characteristic morphological features of arteriovenous malformation. Catheter pulmonary angiography can also establish the diagnosis of arteriovenous malformation, but is not required for this purpose- the typical CT manifestations of arteriovenous malformation are sufficient in this regard. Both a positive echocardiographic bubble study and systemic shunting to be visualized on a 99mTc-macroaggregated albumin ventilation-perfusion scintigraphy study are evidence of right-to-left shunting, but neither are specific for the diagnosis of arteriovenous malformation).

Further clinical course: The patient underwent contrast-enhanced thoracic CT (Figure 3) as well.

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Figure 3. Panels A-I:  Axial enhanced static thoracic CT scan displayed in lung windows. Lower panel: movie of the axial thoracic CT.

Which of the following represents the next most appropriate step for the treatment of this patient? (Click on the correct answer to move to the next panel)

  1. Assessment of shunt via breathing 100% oxygen with therapy only if significant shunt is demonstrated
  2. Catheter pulmonary angiography with coil or detachable balloon embolization of the arteriovenous malformation
  3. Percutaneous transthoracic CT-guided placement of coils or plugs within the lingular arteriovenous malformation
  4. Thoracotomy for resection of the lingular arteriovenous malformation
  5. Video-assisted thoracoscopic resection of the lingular arteriovenous malformation

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