Short Protocols Help MRI Breast Cancer Screening
MRI for breast cancer screening is not used widely enough, even within recent guideline recommendations. Christiane Kuhl showed ways to initiate change.
“MRI finds a large numbers of cancers, but is this overdiagnosis? – Not necessarily,” said Kuhl. A cancer’s detectability is determined by its angiogenic and protease activity. MRI has a bias towards progressive and prognostically relevant cancers and DCIS.
Enhancement in MRI is also a strong biomarker for the prognostic importance of DCIS: If the lesion does not enhance, it is likely prognostically unimportant, i.e. overdiagnosis. “MRI alone as a screening method would help to avoid such overdiagnosis,” said Kuhl.
How is this Put into Practice?
Kuhl cited a US study from five US Breast Cancer Surveillance Consortium Registers that evaluated MRI use in community practices (Wernli 2014). Data showed that out of 25.620 women eligible for MRI due to a lifetime breast cancer risk of more than 20%, only 384 actually received an MRI. “Only 1.5 percent of women who should get an MRI do in fact get it,” underlined Kuhl. She believes cost and a lack of MRI availability are the main reasons.
Simple and Short – Abbreviated breast MRI
In order to reduce cost and increase availability, she and her team have developed an abbreviated protocol (AB-MRI), consisting of one pre- and one post-contrast acquisition (Kuhl 2014). It needs three minutes table time. Maximum intensity projection (MIP) images are then used to detect significant enhancement. This takes expert readers less than three seconds. “It was too short to measure exactly,” commented Kuhl. If there is enhancement, FAST images are used to characterize the enhancement. The time to read the individual subtracted images was 28±23 seconds.
AB-MRI has shown an additional cancer yield of 18.3 per 1000 women per year. The mean tumor size was 8.4mm, the median 8.0mm. The diagnostic accuracy was as good as with the full MRI protocol.
Since Kuhl’s initial publication in 2014, 18 other trial with more than 7,000 women on the same topic have been published, all supporting Kuhl’s findings.
First results of the currently ongoing ECOG/ACRIN trial comparing AB-MRI and digital tomosynthesis will be published this year. “AB-MRI has the potential to make MRI suitable for mass screening,” concluded Kuhl.
An audience member asked Kuhl whether fat-sat should be used or not. It should not, she answered: “Fat is the only contrast we use in mammography, it delineates the lesion’s morphology”. She added that fat-sat is used in the US. “I believe that is, because breast radiologists were not involved in the guideline board meetings.
With regards to MRI cost she noted that these calculations should be done “once we have machines with fast throughput.”
The last question inquired about contrast use for breast MRI. “We use five to six milliliters of Gadovist,” answered Kuhl. Regarding gadolinium retention in the brain Kuhl remarked that “we are encouraged by the current findings that Gadovist is not retained for a length of time.”
Kuhl CK et al. Abbreviated breast magnetic resonance imaging (MRI): first postcontrast subtracted images and maximum-intensity projection-a novel approach to breast cancer screening with MRI. J Clin Oncol. 2014 Aug 1;32(22):2304-10.
Wernli KJ et al. Patterns of breast magnetic resonance imaging use in community practice. JAMA Intern Med. 2014;174(1):125-32.
Related content: Breast, MRI
Presentation Title: Using Abbreviated Protocols
Speaker: Christiane Kuhl, Aachen University, Germany
Date: Wednesday, 27th February 2019
Session Code: SY 1