Extravasation from venous catheter: a serious complication potentially missed by lung imaging.

Three patients were referred for lung ventilation and perfusion (V/Q) imaging with symptoms strongly suggestive of pulmonary embolus (PE). Chest roentgenograms and xenon ventilation studies on all three were normal, save for prominent mediastinal silhouettes and effusions. Technetium-99m macroaggregated albumin (Tc-99m MAA), when injected through the central venous catheter (CVP), revealed mediastinal localization, whereas antecubital injections showed normal pulmonary perfusion. Contrast fluoroscopy introduced through the venous catheter in the first patient defined the extravasation. For patients under strong suspicion of PE, with a venous catheter whose distal tip is seen about the level of the heart on chest radiograph, we recommend administering the perfusion agent slowly through the central catheter to exclude catheter-induced complications. When extravasation is detected, injection of Tc-99m MAA by peripheral vein should be used to exclude PE.