Triple-split-bolus versus single-bolus CT in abdominal trauma patients: a comparative study.

Background Split-bolus computed tomography (CT) is a recent development in trauma imaging. Instead of multiple scans in different contrast phases after a single contrast bolus, split-bolus protocols consist of one single scan of the thorax and abdomen after two or three contrast injections at different points of time. Purpose To evaluate and compare image quality and injury findings of a new triple-split-bolus CT (TS-CT) protocol of thorax and abdomen with those of a portal venous phase CT (PV-CT) in the same patient group. Material and Methods Trauma patients in 2009-2012 who underwent both the TS-CT initially and a PV-CT during the next six weeks were included. The TS-CT examination was performed as one CT run after application of three contrast boluses (total 175 mL) to enhance renal pelvis and urinary tract, the abdominal organs, and the large arterial vessels. The PV-CT had a fixed delay of 85 s. We measured attenuation in Hounsfield units (HU), evaluated possible organ injury and assessed image quality on a 5-point scale. Results Thirty-five patients were included. Attenuation measurements of major abdominal vessels, organs, and renal pelvis were significantly higher with the TS-CT protocol. Performance in organ injury diagnosis and image quality was equal in both protocols. Conclusion The overall performance of the TS-CT protocol is similar to the standard PV-CT. Excellent visualization of the arterial tree and the collecting system may eliminate the need for separate scans.

Quantitative Measurements Versus Receiver Operating Characteristics and Visual Grading Regression in CT Images Reconstructed with Iterative Reconstruction: A Phantom Study.

RATIONALE AND OBJECTIVES: This study aimed to evaluate the correlation of quantitative measurements with visual grading regression (VGR) and receiver operating characteristics (ROC) analysis in computed tomography (CT) images reconstructed with iterative reconstruction. MATERIALS AND METHODS: CT scans on a liver phantom were performed on CT scanners from GE, Philips, and Toshiba at three dose levels. Images were reconstructed with filtered back projection (FBP) and hybrid iterative techniques (ASiR, iDose, and AIDR 3D of different strengths). Images were visually assessed by five readers using a four- and five-grade ordinal scale for liver low contrast lesions and for 10 image quality criteria. The results were analyzed with ROC and VGR. Standard deviation, signal-to-noise ratios, and contrast-to-noise ratios were measured in the images. RESULTS: All data were compared to FBP. The results of the quantitative measurements were improved for all algorithms. ROC analysis showed improved lesion detection with ASiR and AIDR and decreased lesion detection with iDose. VGR found improved noise properties for all algorithms, increased sharpness with iDose and AIDR, and decreased artifacts from the spine with AIDR, whereas iDose increased the artifacts from the spine. The contrast in the spine decreased with ASiR and iDose. CONCLUSIONS: Improved quantitative measurements in images reconstructed with iterative reconstruction compared to FBP are not equivalent to improved diagnostic image accuracy.

EVALUATION OF OCCUPATIONAL RADIATION DOSE IN TRANSCATHETER AORTIC VALVE IMPLANTATION.

Occupational doses during fluoroscopy in interventional procedures vary largely (Kim et al. (Occupational radiation doses to operators performing cardiac catheterization procedures. Health Phys. 2008;94:211-227)). In transcatheter aortic valve implantation, the operators' positions and use of radiation shielding are particularly related to the entry choice on the patient's heart. This study evaluates how occupational doses depend on operator positioning during transfemoral and transaortal access. Occupational dosimetric readings were collected with electronic dosemeters on two cardiothoracic surgeons and one cardiologist during 31 procedures. The findings were significantly higher body doses and eye lens doses to the surgeons during transaortal access compared to transfemoral access. The median equivalent eye lens dose per procedure received by the cardiologists was 0.05-0.06 mSv; hence, the cardiologists should wear protective eye wear to prevent reaching the proposed annual dose limit of 20 mSv to the eye lens. Surgeons ought to use protective eye wear as well, and should only perform a restricted number of transcatheter aortic valve implantations with transaortal access annually.