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Keywords:
CT, Trauma, Emergency, Abdomen, Contrast agent-intravenous, Radiation safety
Authors:
R. Lakshmanan1, R. M. Mendelson2, S. Rao2, P. D. Fatovich2; 1Perth, Western Australia/AU, 2Perth/AU
DOI:
10.1594/ecr2015/C-0087
Results
Demographics
Fig. 5: Demographics table
References: Royal Perth Hospital, Radiology Department
- Each group had the same number of patients
- Each group had the same number of males and females
- There was a higher mean age and broader age range for those who underwent the new protocol.
Objective quality measures (HU)
Fig. 6: Comparison of HU measures between the cases and controls
References: Royal Perth Hospital, Radiology Department
Fig. 7: Statistical significance of the higher HU values in the case group.
References: Royal Perth Hospital, Radiology Department
- Patients who underwent the new triple fractionated scanning protocol (case group) had higher average HU measurements in the aorta,
portal vein,
IVC and best enhancing renal pelvis,
see Fig. 6.
- The higher hounsfield units recorded in the case group were statistically significantly higher,
see Fig. 7.
Subjective quality measures (visual analog scale 0 - 10cm)
Fig. 8: Average subjective quality scores for each reviewer and across all reviewers (yellow).
References: Royal Perth Hospital, Radiology Department
- The average subjective arterial,
portal venous,
renal pelvic and overall quality scores were 70 or above out of 100 on the visual analogue scale,
see Fig. 8.
- Intra-class correlation measures4,5 show that only arterial and renal pelvic subjective quality measures had acceptable inter-observer reliability.
Radiation dose
Fig. 9: Radiation dose statistics
References: Royal Perth Hospital, Radiology Department
- The new triple fractionated contrast injection protocol had a lower mean and a lower median radiation dose compared to the control group,
see Fig. 9.
- The new protocol group was associated with the lowest minimum radiation dose,
see Fig. 9.
Scan phases performed
Patients who underwent the triple fractionated contrast injection protocol had no additional scan phases performed.
11 patients under the old protocol required additional scan phases
- 7 had one additional phase – 2x non-con,
3x arterial,
2x delayed
- 3 had two additional phases – 2x non-con+ arterial,
1x arterial + delayed
- 1 had three additional phases – 1x non-con + arterial + delayed
Follow up
- Follow up of the clinical notes showed no adverse events relating to the 40 - 60mL of additional contrast received by those on the new protocol.
Anecdotal Cases Illustrating Utilty of Triple Fractionated Injection Technique
Fig. 10: Detection of extraperitoneal bladder rupture on the initial scan due to the presence of delayed contrast obviated the need for a further CT cystogram.
References: Royal Perth Hospital, Radiology Department
- Extraperitoneal bladder rupture was diagnosed on the initial CT in a patient with multiple pelvic fractures,
this avoided the patient having a further CT cystogram to reach the diagnosis of extraperitoneal bladder rupture,
saving radiation dose,
see Fig. 10.
Fig. 11: Patient with high grade renal trauma showing no evidence of collecting system injury eliminating the need for a further delayed study.
References: Royal Perth Hospital, Radiology Department
- In a patient with renal lacerations extending into the renal hilum the presence of delayed contrast in the collecting systems reassuringly showed no evidence of collecting system injury.
This patient did not need a further delayed CT,
again saving radiation dose,
see Fig. 11.