Improved CT-detection of acute bowel ischemia using frequency selective non-linear image blending

Sven Schneeweiss; Michael Esser; Wolfgang Thaiss; Hans Boesmueller; Hendrik Ditt; Konstantin Nikolau; Marius Horger

doi:10.1177/2058460117718224

Improved CT-detection of acute bowel ischemia using frequency selective non-linear image blending

Acta Radiol Open. 2017 Jul 10;6(7):2058460117718224. doi: 10.1177/2058460117718224. eCollection 2017 Jul.

Authors

Sven Schneeweiss¹, Michael Esser¹, Wolfgang Thaiss¹, Hans Boesmueller¹, Hendrik Ditt², Konstantin Nikolau³, Marius Horger³

Affiliations

¹ Institute of Pathology, University Hospital Tuebingen, Tübingen, Germany.
² Siemens Healthcare GmbH, Erlangen, Germany.
³ Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tübingen, Germany.

Abstract

Background: Computed tomography (CT) as a fast and reliable diagnostic technique is the imaging modality of choice for acute bowel ischemia. However, diagnostic is often difficult mainly due to low attenuation differences between ischemic and perfused segments.

Purpose: To compare the diagnostic efficacy of a new post-processing tool based on frequency selective non-linear blending with that of conventional linear contrast-enhanced CT (CECT) image blending for the detection of bowel ischemia.

Material and methods: Twenty-seven consecutive patients (19 women; mean age = 73.7 years, age range = 50-94 years) with acute bowel ischemia were scanned using multidetector CT (120 kV; 100-200 mAs). Pre-contrast and portal venous scans (65-70 s delay) were acquired. All patients underwent surgery for acute bowel ischemia and intraoperative diagnosis as well as histologic evaluation of explanted bowel segments was considered "gold standard." First, two radiologists read the conventional CECT images in which linear blending was adapted for optimal contrast, and second (three weeks later) the frequency selective non-linear blending (F-NLB) image. Attenuation values were compared, both in the involved and non-involved bowel segments creating ratios between unenhanced and CECT.

Results: The mean attenuation difference between ischemic and non-ischemic wall in the portal venous scan was 69.54 HU (reader 2 = 69.01 HU) higher for F-NLB compared with conventional CECT. Also, the attenuation ratio between contrast-enhanced and pre-contrast CT data for the non-ischemic walls showed significantly higher values for the F-NLB image (CECT: reader 1 = 2.11 (reader 2 = 3.36), F-NLB: reader 1 = 4.46 (reader 2 = 4.98)]. Sensitivity in detecting ischemic areas increased significantly for both readers using F-NLB (CECT: reader 1/2 = 53%/65% versus F-NLB: reader 1/2 = 62%/75%).

Conclusion: Frequency selective non-linear blending improves detection of bowel ischemia compared with conventional CECT by increasing attenuation differences between ischemic and perfused segments.

Keywords: Computed tomography (CT); bowel ischemia; contrast enhancement; non-linear blending.