Lower voltage CT just as effective at finding lung blockage in those with higher BMIs

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Reducing CT tube voltage in obese pulmonary angiography patients does not yield lower quality results, according to a study made available online Oct. 24 by Clinical Radiology.

As radiologists strive for image clarity when looking for pulmonary embolism (PE), there is also push for lower radiation doses, which can be achieved when using 100 kVp tube voltage, versus the previous standard protocols of 120 or 140 kVp.

According to the researchers, led by Boglarka Megyeri, MD, with the University of Debrecen Clinical Centre in Hungary, a hindrance to image clarity with the low voltage technique is both high body weight (BW) and body mass index (BM), as these cause high levels of noise in the images.

“The purpose of the current analysis was to assess the image quality and diagnostic confidence of CTPA [CT pulmonary angiography] using 100 kVp in various BW and BMI groups above 75 kg, with special emphasis on patients weighing more than 100 kg,” Megyeri and colleagues wrote.

With 216 participants divided among bodyweights (75 to 99 kg, 100 to 125 kg and more than 125 kg), they each received 100 kVP CTPA to exclude PE and both attenuation and contrast-to-noise (CNR) was calculated in the pulmonary trunk.

The study showed 100 kVp CTPA provides similar image quality and diagnostic confidence in PE patients both above and below 100 kg.

“These data suggest that the 100 kVp CTPA can be used safely in the surveyed BW range, which was 75–150 kg, although the number of patients weighing 125–150 kg was low,” the research team wrote. “To the authors' knowledge, this is the first investigation that targets image quality and diagnostic confidence with 100 kVp CTPA in patients with high BW or obesity.”

Additionally, there was no difference in confidence between obese, overweight and normal weight patients according to the BMI-based data analysis.

“The present results reflect the rather complex effect of various patient size measurements and objective image quality criteria on subjective image quality and diagnostic confidence,” Megyeri and team wrote.

They noted further studies are needed to determine the most effect noise-leveling settings that do not compromise image reading.

“The applicability of 100 kVp in the 125–150 kg BW range needs further testing in larger collectives,” the authors wrote.