In blunt trauma patients, low-dose whole body computed tomography (WBCT) does not seem to increase the risk of missed injury diagnoses compared with standard-dose protocols, and almost halves exposure to diagnostic radiation, a quasi-experimental study suggests.
“In suspected multiple trauma, radiological imaging…plays an integral role during initial work-up and resuscitation,” Dr. Dirk Stengel of BG Kliniken-Klinikverbund der Gesetzlichen Unfallversicherung gGmbH in Berlin told Reuters Health by email. “In industrialized countries and at designated trauma centers, an early WBCT scan from the skull to the pelvis – often coined the ‘pan-scan’ – emerged as a preferred option to screen for life-threatening injuries.”
“As many patients are rather young,” he said, “excess radiation with a liberal pan-scan policy remains an issue of debate.”
Several imaging approaches for reducing noise and radiation in CT technology are available from major manufacturers of high-end multisclice scanners, he noted. “No previous large-scale study had investigated the clinical effects – i.e., rate of missed injuries, diagnostic accuracy – of lowering the radiation dose to the currently achievable minimum.”
Dr. Stengel and colleagues recruited 565 consecutive patients admitted for suspected blunt multiple trauma from September 2014 through July 2015 for the standard-dose protocol, and 509 patients from August 2015 through August 2016 for the low-dose protocol.
As reported in JAMA Surgery, 971 patients (mean age, 52.7; 66.8% men) completed the study. One hundred and fourteen (11.7%) had multiple trauma, defined as an Injury Severity Score of 16 or greater.
A missed injury diagnosis at the point of care was defined as any injury demanding clinical awareness or therapeutic action at any time, but that was not recognized in the initial WBCT or contained in the initial (“hot”) report provided to the trauma team.
The proportion of patients with any such injury was 23.3% in the standard-dose and 21.3% in the low-dose WBCT groups (unadjusted odds ratio, 0.89). Adjustments for autocorrelation and multiple confounding variables did not alter the results.
Radiation exposure, measured by the volume CT dose index, was lowered from a median of 11.7 mGy in the standard-dose group to 5.9 mGy in the low-dose group. The median dose-length product was reduced from 1,109 mGy/cm to 735 mGy/cm.
Further, the contrast-to-noise ratio consistently favored low-dose WBCT for all investigated anatomical regions.
Dr. Stengel said, “We conclude that, if WBCT scanning is considered the diagnostic strategy of choice, it should be performed at low-dose using a modern iterative image-processing algorithm.”
With that said, based on a 2012 report from the same team (http://bit.ly/2Gi4Mob), “we stress that an initially ‘negative’ WBCT scan is not confirmative,” he added. “Certain injuries in trauma patients simply need time to demark. In the early phase of resuscitation, patients may have a centralized circulatory system, and active bleeding to the large body cavities – i.e., cranium, thorax, abdomen, retroperitoneum, pelvis – can only be detected after volume has been replaced.”
“We urge trauma teams worldwide to find the appropriate balance amongst the ideal time of scheduling patients to a WBCT scan and its capability to detect injuries,” he concluded.
Dr. Anthony Charles of the University of North Carolina at Chapel Hill, coauthor of a related editorial, noted in an email to Reuters Health that although it was a good study, he has concerns.
“In trauma, there is acuity, and the risk of missed injury is much higher than a very low potential risk of radiation-induced cancer in the future,” he said. “In addition, this study had a high baseline risk of missed injury within the regular and low-dose WBCT groups – certainly, a lot higher missed injury rate than we see in the United States.”
“If they had missed injury rates similar to the U.S., this study would have shown that low-dose WBCT resulted in a higher missed injury rate,” he said.
“The strength of any radiologic study is in the image quality and the interpretation,” he added. “Radiologists as well as trauma surgeons (who also must concur with the radiologist interpretations of any image) must be confident that low-dose WBCT can yield the same results. This will take time and practice, but more importantly, more robust studies before one can allow low-dose WBCT to go mainstream.”
Source : Medscape