Botched contrast uptake? Try post-processing—that should fix it right up

A German-Belgian group of researchers used post-processing tools to reduce repeat imaging when diagnosing pulmonary embolism, publishing their research in the February issue of Academic Radiology.

Pulmonary embolism is one of the most common causes of death in the U.S.; nearly 16 percent of all medical autopsies find a major blockage in a blood vessel in a lung. Successfully treatment is highly time-sensitive, so a diagnosis must be quick and accurate if a patient is to survive. Computed tomography angiography (CTA) has emerged as the modality of choice but sub-optimal contrast uptake can hamper diagnostic efforts, resulting in repeated scans.

“This translates to a double radiation exposure for the patient, as well as a double amount of contrast agent,” the authors wrote. “This is particularly crucial in patients with renal failure, young patients, or patients with a low probability of pulmonary embolism.”

Instead of doubling a patient’s dose, clinicians can use widely available post-processing tools to clear up the image, giving them more confidence in their diagnosis. Study authors used vContrast, a Phillips Healthcare-developed tool that uses low contrast clustering and structures enhancement to bring suboptimal images up to diagnostic standards.

Using imaging from 41 patients with sub-optimal contrast uptake, researchers measured diagnostic image quality with quantitative criteria such as image noise and qualitative criteria such as the opinions of independent radiologists.

They found vContrast to be an effective tool for boosting the quality of imaging with poor contrast. While image noise remained about the same, the main pulmonary artery was significantly easier to see, adding diagnostic value to the imaging.

“The CT density of the contrast-filled pulmonary arteries is increased on vContrast images, and the discrimination of embolus and enhanced vessels is better on vContrast images compared to the standard images with low contrast of the pulmonary arteries,” the authors wrote.

Reducing patient dose is a hot topic in the imaging community, but lowering contrast dose doesn’t get the attention it deserves, according to the authors.

“Contrast media load on individual patients can result in significant side effects, notably renal complications especially in elderly patients or patients with preexisting renal dysfunction,” they wrote. “Further, with a body weight-dependent contrast load and a growing number of obese individuals (currently represent more than one-third of US adults), a growing number of patients with side effects can be expected in the near future, causing a further increase in cost for the public health sector.”

The authors see possibilities beyond studies with botched contrast, saying this post-processing technology could potentially be used to reduce contrast dose across the board. However, they acknowledge that current-day technology is better suited for adding diagnostic value to existing imaging, rather than as a standalone assessment.

“We believe that the main goal of CT imaging of the pulmonary vessels remains an optimized time management for excellent contrast opacification of the pulmonary arteries. However, vContrast is intended to be a complement to the original examination dataset for improved detectability of PE,” the authors wrote. “So we recommend vContrast as a feasible additive tool for diagnostic evaluation of suboptimal contrast-enhanced pulmonary arteries.”