Low-Dose CT Scans Can Diagnose Appendicitis Accurately

By Lorraine L. Janeczko

November 29, 2021

NEW YORK (Reuters Health) - Low-dose CT scans appear to diagnose appendicitis accurately while exposing patients to less radiation, according to a study from Finland.

Low-dose and standard-dose CT scans were similarly accurate in identifying appendicitis and in differentiating cases that required surgery from those that could be treated with antibiotics alone.

"The results of this study suggest that the diagnostic CT scan radiation dose can be significantly decreased without impairing diagnostic accuracy," Dr. Paulina Salminen of the University of Turku said in a press release. "These findings will hopefully encourage physicians to implement low-dose CT modalities at emergency departments for acute appendicitis imaging to avoid unnecessary radiation in this very large patient population."

As reported in British Journal of Surgery, Dr. Salminen and her colleagues examined prospective data from a cohort of patients over 16 years of age who had suspected appendicitis. They compared the CT diagnosis with the final clinical diagnosis to determine the diagnostic accuracy of contrast-enhanced low- vs. standard-dose CT.

Of the 856 patients receiving diagnostic CT, 454 received a low radiation dose and 402 patients received a standard dose. The overall accuracy of low-dose vs. standard-dose CT scans in identifying patients with and without acute appendicitis was 98.0% and 98.5%, respectively. In patients with a BMI under 30 kg/m2, the accuracy was 98.2% for the 434 low-dose patients and 98.6% for the 210 standard-dose patients (P=1.0).

For all patients, the corresponding accuracy for differentiating between uncomplicated and complicated acute appendicitis was 90.3% and 87.6%. For those with BMI below 30 kg/m2, the corresponding accuracy was 89.8% and 88.4%, respectively (P=0.663).

Among all patients, the median low and standard radiation doses were 3 mSv and 7 mSv, respectively. Among patients with a BMI below 30 kg/m2, the median low and standard doses were 3 mSv and 5 mSv, respectively (P<0.001).

Dr. Rinat Masamed, a diagnostic radiologist at UCLA Health, in Los Angeles, told Reuters Health by email, "The findings are not surprising. At our institution, we have steadily reduced the dose of all CT examinations over the past several years and have shown that there is little to no difference in image quality and accuracy of interpretation in most cases."

"These results are encouraging," Dr. Masamed, who was not involved in the study, added, "but the study did not explore the differences in sensitivity and specificity of low-dose vs. standard-dose CT in higher-BMI individuals, who comprise a large portion of our population."

Dr. Benjamin M. Yeh, a professor of radiology and biomedical imaging at the University of California, San Francisco, said, "It is attractive to think that CT radiation doses can be readily reduced across the board without detriment to patient care. But in real life, CT radiation dose reduction is tricky."

"Lower-end CT scanners generally require higher radiation doses to produce similar-quality images as advanced scanners," Dr. Yeh, who also was not involved in the study, told Reuters Health by email. "Patients with BMI <30 kg/m2 still comprise a wide range of patient sizes. To achieve similarly diagnostic CT images, a tall person with low BMI requires a greater radiation dose than a short person with a similar BMI. Artificial intelligence may help sort through the myriad factors to help adjust radiation dose on a more granular level."

Dr. Salminen was unable to provide comments about the study in time for publication.

SOURCE: https://bit.ly/3nF6J4m British Journal of Surgery, online November 11, 2021.

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