Breast Imaging
Christiane Kuhl

Synopsis

. We proposed an abbreviated, short MRI-protocol that is limited to the early post-contrast period, then to use standard image reconstruction tools (maximum intensity projection, MIP) to allow a very fast overview of the imaging volume, and finally to have expert radiologists interpret this limited protocol. Aim was to substantially reduce image acquisition and reading time of screening-MRI. Long term goal is to increase the access to screening breast-MRI.

Breast-MRI screening is associated with high direct and indirect costs. This, together with the lack of sites that offer high level breast-MRI, limits the clinical access to screening MRI. One reason for the high cost is the fact that current breast-MRI protocols are time consuming to acquire and to read. A typical MRI study occupies the MR system for up to 40 minutes and generates several hundred images. Although MRI pulse-sequence protocols of the different MRI-screening trials conducted so far vary widely, they all have in common that for screening, the same MRI acquisition-protocol had been used that was also used for diagnostic purposes in the respective institutions. Mammographic screening, on the other hand, is a highly standardized and relatively simple procedure. Women undergo mammography, usually without clinical examination, and the resulting mammograms are interpreted by highly trained and specialized screening radiologists who batch read up to 100 mammograms per hour. To solve this dilemma, we proposed to use an approach to breast-MRI screening that pursues a concept similar to that of mammographic screening programs. We proposed an abbreviated, short MRI-protocol that is limited to the early post-contrast period, then to use standard image reconstruction tools (maximum intensity projection, MIP) to allow a very fast overview of the imaging volume, and finally to have expert radiologists interpret this limited protocol. Aim was to substantially reduce image acquisition and reading time of screening-MRI. Long term goal is to increase the access to screening breast-MRI. We hypothesized that an abbreviated protocol, i.e. withholding diagnostic information, should be associated with a reduced diagnostic accuracy, but suspected that it may be acceptable to give up some of the very high sensitivity of regular screening breast-MRI, and trade it for acquisition and interpretation speed. In a prospective reader study, followed by a two-year validation phase, we recruited 443 women who underwent a total 606 screening rounds with the abbreviated and the full breast MRI screening protocol. The abbreviated protocol consisted of only one pre- and one post contrast acqusition, plus the respective First Post Contrast Subtracted, or FAST, images, and their MIP reconstruction. Women at moderately to mildly increased risk were offered MRI for screening only if they had undergone two view digital mammography, double read by two experienced breast radiologist with negative or benign results, as well as a high resolution ultrasound screening study of the breast, conducted by dedicated breast radiologist, again with negative or benign results. We found that the diagnostic utility of the abbreviated breast-MRI screening protocol was comparable or even identical to that of the routine breast-MRI screening protocol. The abbreviated protocol, however, allowed a substantial reduction of image acquisition time (i.e. MR system time of 3 minutes) as well as image interpretation time (i.e. expert radiologist reading-time of 3 seconds for MIP, and under 30 seconds for the FAST images). Reading the MIP-image helped exclude presence of breast-cancer with a negative predictive value of close to 100 %. Reading FAST images helped correctly characterise positive MIP findings. With the abbreviated protocol, the same added cancer yield was achieved as with the regular screening breast-MRI protocol. In conclusion, our study suggests that with the “abbreviated breast MRI” approach introduced by us, screening breast-MRI is feasible without compromise on sensitivity and specificity compared with the regular full diagnostic MRI protocol. Abbreviated breast-MRI screening could thus be used to open up the opportunity for “batch MRI screening” according to the model of mammographic screening, and pave the ground for a broader use of MRI for screening.

Acknowledgements

No acknowledgement found.

References

Kuhl CK, Schrading S, Strobel K, Schild HH, Hilgers RD, Bieling HB. 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. doi: 10.1200/JCO.2013.52.5386. Epub 2014 Jun 23. PubMed PMID: 24958821.

Mango VL, Morris EA, David Dershaw D, Abramson A, Fry C, Moskowitz CS, Hughes M, Kaplan J, Jochelson MS. Abbreviated protocol for breast MRI: are multiple sequences needed for cancer detection? Eur J Radiol. 2015 Jan;84(1):65-70. doi: 10.1016/j.ejrad.2014.10.004. Epub 2014 Oct 16. PubMed PMID: 25454099.



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)