Abbreviated Breast MRI for Screening
Kuhl CK, Schrading S, et. al.
Introduction
MRI associated with high direct and indirect costs
conventional protocols time consuming to acquire and read
limited access to screening MRI
Introduction
Propose abbreviated MRI protocol
early postcontrast period only
MIP for fast overview of imaging volume
Reduce time and cost associated with screening breast MRI
Increase access
Methods - design
Prospective, 2009 - 2010
Hypothesized abbreviated protocol (AP) associated with reduced diagnostic accuracy
May be worth it for increased speed/decreased cost
Methods - protocol
T1 pre
T1 post (1st acquisition)
T1 subtracted
MIP
T1 post (2nd acquisition)
T1 post (3rd acquisition)
T1 post (4th acquisition)
T1 post (5th acquisition)
Coronal T1
Axial T2
Methods - inclusion
Women referred for screening MRI on clinical grounds
24% Dense breast tissue
26% Family history
50% Personal history (screening contralateral breast)
Methods - interpretation
Two readers, 18 and 6 years experience
Images read immediately
1st with AP
MIPs read first, recorded presence of abnormal enhancement
then rest of AP, given BI-RADS category
then with FDP (full diagnostic protocol)
Time to establish diagnosis recorded
Results - participants
443 women (163 underwent 2 annual screening rounds)
606 MRIs
82% of exams in women with mildly or moderately increased risk
All were asymptomatic and had negative or benign mammogram at time of MRI
427 of 606 had negative or benign US
Results - cancer yield
11 cancers diagnosed (incidence = 2.5%)
4 DCIS
7 invasive
All had (false) negative or benign mammograms
10 of 11 had (false) negative or benign US, 11th had negative targeted US at site of MRI detected cancer
8 high-risk lesions
3 papillomas
2 LCIS
2 ADH
1 radial scar
Results - timing
Acquisition time
AP: 3 m, 4 s
FDP: 17 m, 4 s
Reading time
MIP: 2.8 s
AP: 28 s
Results - diagnostic accuracy
p=0.317
Discussion
Cancer yield and diagnostic accuracy equivalent between abbreviated and full protocols
Substantially reduced time of acquisition and reading
NPV of MIPs alone 99.8%
Sens/spec of AP identical to FDP
Discussion
FDP mainly needed for lesion characterization
38% of BI-RADS 3 lesions diagnosed on FAST images downgraded to BI-RADS 2 after reading full protocol
Will decreased costs of AP justify increase in BI-RADS 3 diagnoses?
Discussion - limitations
High volume MRI readers, perhaps not transferrable to community practice
Editorial -
Elizabeth Morris
MRI superior to mammography and US
Likelihood of finding cancer at biopsy < 10% if performed on basis of US findings, 30% if on basis of MRI findings
MRI geared to detect more biologically relevant cancers (neovascularity, inflammation)
Editorial
Currently, MRI limited to high risk populations
Limited access
expensive
time-consuming
Editorial
FAST MRI could reduce barriers to MRI screening
MRI screening should be offered to all eligible patients
MRI should be next additional screening modality, not US
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