New imaging technology significantly reduces radiation exposure during uterine artery embolization

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A study presented at the Society of Interventional Radiology’s (SIR’s) 2015 annual scientific meeting reveals that a new angiographic imaging platform (AlluraClarity, Philips Healthcare) maintains similar procedure time as a current C-arm imaging platform (Allura, Philips), yet with substantially reduced radiation exposure for uterine artery embolization procedures.

These findings have particular relevance for the many women undergoing uterine artery embolization who are of child-bearing age, as well as for the interventional radiology staff present in the room during the procedure.

Rüdiger Egbert Schernthaner, a member of Jean-Francois Geschwind’s research team at the Johns Hopkins University, Baltimore, USA, set out to quantify the radiation exposure reduction of a new C-arm imaging platform for women with symptomatic uterine fibroids who were treated with uterine artery embolization. 

In this ongoing prospective trial, twenty nine consecutive patients with symptomatic uterine fibroids were treated either on the new dose reduction imaging platform (n=15; AlluraClarity) or the reference imaging platform (n=14; Allura). X-ray dose logging was performed using a dedicated Radiation Dose Structured Reporting (RDSR) server.

The new system uses optimised acquisition parameters to lower the radiation exposure and real-time image processing algorithms such as noise reduction, temporal averaging and automatic pixel shift to restore the image quality.

Air kerma, the radiation exposure in free air before reaching the body, dose area product, the absorbed radiation dose multiplied by the area irradiated and acquisition time for digital fluoroscopy and digital subtraction angiography were recorded. The body mass index of patients was also noted. Unpaired t-tests and Wilcoxon rank-sum tests were used to assess statistical differences between the platforms. 

The investigators found that there was no difference in body mass index between the two patient cohorts. “Additionally, there was no significant difference in digital fluoroscopy or digital subtraction angiography time between the new and reference platforms, indicating that the procedure courses were similar between the two cohorts,” Schernthaner said.

“Compared to the reference platform, the new platform significantly reduced the cumulative air kerma and dose area product by 57% and 66%, respectively (p2, p=0.04) and 80% (65.5 vs. 320.5 Gy*cm2, p<0.001), respectively,” he reported.

“The reduction of radiation exposure to only 20% of the standard system during digital subtraction angiography is especially important when considering that a number of interventional radiologists reported during the SIR meeting that they restrict the use of digital subtraction angiography in an attempt to lower the radiation exposure, but at the cost of an increased risk of non-target embolization,” Schernthaner explained.

Schernthaner is an attending radiologist at the Medical University of Vienna, Vienna, Austria.


Dose reduction for visceral embolization procedures

A similar study, also presented at the SIR annual meeting, that set out to evaluate the impact of a Alluraclarity on radiation dose during visceral embolization procedures for both fluoroscopy and digital subtraction angiography, has found that the new technology lowers the radiation dose during these procedures considerably.

Frederic Baumann, Miami Cardiac & Vascular Institute, Miami Baptist Hospital, Miami, USA, reported the results of the study showing that the ClarityIQ (Philips) technology was shown to significantly reduce radiation dose for visceral embolization procedures.

Baumann told delegates that dose was highly reduced even in patients with increased body mass index. “Therefore, further scrutiny of this new imaging software is warranted for endovascular therapies,” Baumann said.

The researchers included data from a consecutive series of patients undergoing endovascular visceral embolization to carry out a retrospective, single-centre data analysis after approval by the local institutional review board. They compared the data from visceral procedures performed between July 2013 and April 2014 using ClarityIQ technology data from patients treated with the former AlluraXper technology, which was used from May 2011 to June 2013.

Baumann and colleagues categorised patients into three groups based on their body mass index: group 1 included patients whose body mass index was less than 25 kg/m2; group 2 included those whose body mass index was above 25 and below 30 kg/m2 and group 3 included patients whose body mass index I was greater than 30 kg/m2. They also measured procedure time, fluoroscopy time, the total dose of ionised contrast administered and air kerma for the quantification of radiation dose were obtained. Air kerma was furthermore adjusted per fluoroscopic minute (AirKerma PFM).

“A total of 100 patients using ClarityIQ (59 were male, mean age: 70.6 years) were compared to 139 patients using AlluraXper (71 were male, mean age: 70.1 years). We found that the procedure time was shorter for AlluraXper (91.4 vs. 108.3 minutes, p=0.004), whereas fluoroscopy time and the amount of contrast media were equally distributed,” Baumann said.

He noted that comparing ClarityIQ and AlluraXper, airKerma was 1342.9±1080.1 vs. 2214.8±1826.8 (p<0.001) and AirKerma PFM was 61.8±47 vs. 103.2±65.6 (p<0.001), respectively.