Split-bolus single-pass CT for vascular complications in acute pancreatitis: assessment of radiation dose and multi-phasic contrast enhancement compared to single-bolus multi-pass CT.

AIM: To assess vascular contrast enhancement and radiation dose of split-bolus single-pass computed tomography (CT) compared to single-bolus multi-pass CT for acquiring a multi-phasic study. MATERIALS AND METHODS: Patients who underwent CT for acute pancreatitis were included retrospectively. Thirty consecutive patients scanned with a split-bolus protocol were compared to 30 consecutive patients scanned with a single-bolus protocol. Data were collected on attenuation measurements (aorta, portal vein and spleen) and images were assessed for subjective vascular enhancement quality and splenic homogeneity. Radiation dose was measured by dose-length product (DLP). RESULTS: There was no significant difference in the aortic (p = 0.88) or portal vein (p = 0.35) attenuation values between the two groups. The percentage of examinations reaching the target aortic and portal attenuation in the split-bolus group were 96.7% and 93.3%, and in the single-bolus group were 96.7% and 85.7%, respectively. The mean DLP was 492 mGy.cm for the single-bolus group and 940 mGy.cm for the split-bolus group (p < 0.0001). Subjective assessment revealed higher rates of splenic heterogeneity in the split-bolus group. DISCUSSION: In acute pancreatitis, split-bolus imaging can produce arterial and venous enhancement comparable to a multi-pass technique with a significant reduction in radiation dose. Loss of temporal resolution and increased splenic heterogeneity are the main disadvantages. The low prevalence of pseudoaneurysms favours the lower-dose imaging technique.

Quantitative and qualitative assessment of a coding system for reporting CT colonography.

AIM: To validate a coding system implemented to summarise computed tomography colonography (CTC) findings for the detection of suspected colorectal cancer (CRC) by assessing interobserver variability and also to evaluate any weaknesses through qualitative analysis. MATERIALS AND METHODS: All CTC investigations over a 6-month period (01/07/2016 to 31/12/2016) were analysed retrospectively. Each study was read initially by an advanced practitioner radiographer with a final report issued by a consultant gastrointestinal radiologist. Rates of interobserver agreement, using the kappa statistic, provided a quantitative assessment of levels of agreement. Areas of poor interobserver agreement were identified for further qualitative assessment. RESULTS: The present study included 1,321 CTC procedures and the mean age of patients was 68.4 years (range 28-96 years). Percentage agreement for colonic coding was 90% and for extra-colonic coding 47%. This corresponds to kappa scores of 0.69 (substantial agreement) and 0.22 (fair agreement), respectively. Reasons and examples of disagreement in the colonic coding are highlighted. CONCLUSIONS: High interobserver agreement was observed for C coding, suggesting it is a reproducible method of classifying intra-colonic CTC findings. Some of the difference in classifying extra-colonic findings is the perceived importance of incidental findings between readers, as well as differences in skill set; however, some themes recurred in areas of disagreement and recommendations for refining and improving the coding system are provided.

Early experience with a split-bolus single-pass CT protocol in paediatric trauma.

AIM: To determine the adequacy of the split-bolus computed tomography (CT) technique in terms of vascular enhancement and solid-organ injury assessment in paediatric trauma. MATERIALS AND METHODS: A retrospective review was undertaken of all split-bolus trauma CT examinations performed in patients <16 years during the period from 1 January 2015 to 31 January 2016. Twelve examinations were performed in this time on patients with an age range of 2-15 years (mean 10.8) consisting of eight male and four female patients. Abdominal aortic and portal vein attenuation were measured using a region of interest tool. RESULTS: The mean aortic attenuation was 267 HU and mean portal vein attenuation was 203 HU. Five cases of solid-organ injury were detected and the image quality was sufficient to grade the injury and guide clinical management in all cases. DISCUSSION: Although the cohort is relatively small, good arterial and portal venous enhancement were achieved in all but one patient, where there was suboptimal portal venous opacification; however, there were no other patients in the same weight group making it difficult to determine whether this was a systematic problem or due to patient factors. Overall, these findings have reassured us locally that the current protocol should continue to be used, but the performance of the protocol will be audited continually.