Debbie Lee Bennett MD, Presenter: Nothing to Disclose

Leena M. Hamberg PhD, Abstract Co-Author: Nothing to Disclose

Bing Wang MS, MD, Abstract Co-Author: Nothing to Disclose

Joshua A. Hirsch MD, Abstract Co-Author: Consultant, CareFusion Corporation Consultant, Johnson & Johnson Consultant, Koninklijke Philips Electronics NV Shareholder, IntraTech Medical Ltd

Ramon Gilberto Gonzalez MD, PhD, Abstract Co-Author: Nothing to Disclose

George Joseph Hunter MD, Abstract Co-Author: Nothing to Disclose

Delayed image acquisition is often used in head and neck CT angiography (CTA) for evaluation of carotid occlusion and active hemorrhage. However, acquisition of this extra CTA series increases the radiation dose of the examination. The aim of this study was to evaluate how often delayed images provided additional, unique information beyond that seen on the initial phase images and if such information changed patient management.

All CT angiography studies of the head and neck performed between 1/1/09 and 6/30/09 were evaluated. The studies were examined to determine if a delayed image series had been acquired. For each study with delayed images the reports were read; those diagnostic reports that indicated the presence of additional findings on the delayed images, as compared to the initial phase images, were then evaluated by consensus to determine if the additional information was only seen on the delayed series. In those cases where additional information was only seen on the delayed images, further review of the electronic medical record was performed to determine if this information changed patient management.

A total of 1748 CTA examinations were identified. Both early and delayed images were acquired in 624 (36%) of these studies. In 58 of the 624 studies with delayed phase imaging (9.3%), the presence of diagnostic, additional information on the delayed series was recorded in the report. Of these 58 studies, consensus review of the report identified 9 cases (1.4%) where the additional information was derived only from the delayed series. Further review of the electronic medical record found that management decisions for these 9 patients were not changed by the additional delayed series information.

Patient management was not changed by information present on routinely acquired delayed images during head and neck CTA. We suggest that delayed imaging be reserved for very specific indications such as pre-surgical evaluation of a potential string sign, or assessing pseudo-thrombosis of venous sinuses. This would limit increased radiation dose to those patients most likely to benefit from the procedure.

Collection of additional delayed images during head and neck CTA does not change patient management and should be avoided. Furthermore, this also would prevent unnecessary radiation to the patient.

Bennett, D, Hamberg, L, Wang, B, Hirsch, J, Gonzalez, R, Hunter, G, Diagnostic Yield of Delayed Image Acquisition in CT Angiography of the Head and Neck.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002083.html