mammography is the primary imaging modality for the early detection of breast cancer . despite advances in mammographic techniques ( digital )
, mammography still has its limitations with regard to both sensitivity ( 65.685.5% ) and specificity ( 87.794.3% ) .
mammograms are coded using the ordered categories of the american college of radiology ( acr ) breast imaging reporting and data system ( bi - rads ) lexicon : category 1 , negative ; 2 , benign finding ; 3 , probably benign ; 4 , suspicious finding ; 5 , highly suggestive of malignancy .
the diagnostic work - up of breast lesions depends on the bi - rads classification of the breast lesions .
the guideline for non - invasive diagnostic tests for breast abnormalities of the agency for health care research and quality in the united states ( ahrq ) states that breast lesions classified as bi - rads 1 and 2 require no further work - up or follow - up other than routinely called for .
the chance of a bi - rads 4 lesion being malignant varies from 2% to 95% , whereas this chance is over 95% for a bi - rads 5 lesion .
this biopsy procedure can not be replaced by breast magnetic resonance imaging ( mri ) , because histology is obligatory in these cases .
the most difficult mammographic lesions are the lesions that are classified as bi - rads 3 .
the probability of a bi - rads 3 lesion being cancer is considered to be less than 2% . for the work - up of a bi - rads 3 lesion , biopsy or follow - up
, the decision on the work - up of bi - rads 3 lesions depends on the possibilities for biopsy procedures , the wishes of the patient and the preference of the radiologist .
most patients who are referred for a biopsy have benign disease because of the low predictive value of both physical examination and mammography .
the value of breast mri in bi - rads 3 lesions is not yet clear .
breast mri is emerging as a clinically useful additional diagnostic tool and has an excellent sensitivity and negative predictive value ( npv ) , which usually exceeds 90% .
the diagnostic accuracy of breast mri varies with the expertise of the radiologist and the particular patient population studied .
it is important that breast mri is used for those groups of patients for whom there is evidence of acceptable diagnostic accuracy .
breast mri as a first - line imaging modality is performed by screening women at increased risk for breast cancer . as a second - line modality
, breast mri can be used for the following indications : inconclusive findings in conventional imaging , preoperative staging , axillary node malignancy and unknown site of primary tumor , the evaluation of therapy response in the neoadjuvant chemotherapy setting , imaging of the breast after conservative therapy , prosthesis imaging , nipple discharge and mr - guided biopsy and lesion localization .
although the npv of mri in breast cancer is the highest of all imaging techniques and in most cases a negative breast mri excludes malignancy , it is not yet common practice to use breast mri as a problem - solving modality in excluding patients for further diagnostic work - up .
therefore , in this meta - analysis , the usefulness of breast mri as a problem - solving modality in patients with mammographic bi - rads 3 lesions is investigated .
a computerized search was performed to identify relevant studies in medline and embase up to 2010 .
the following strategy was followed in medline :  magnetic resonance imaging  [ mesh term ] or  magnetic resonance imaging  [ text word ] or  mri  [ text word ] or 
mr imaging  [ text word ] and  probably benign lesions  [ text word ] or  microcalcifications  [ text word ] or  inconclusive findings  [ text word ] and mammography [ mesh term ] or mammography [ text word ] and  sensitivity and specificity  [ mesh term ] or  specificity or sensitivity  [ text word ] . in embase
medline and embase were searched for studies that used breast mri as a problem - solving modality in mammographic bi - rads 3 lesions .
studies were included if the following inclusion criteria were met : ( 1 ) all patients underwent a mammography and breast mri ; ( 2 ) the study population had mammographic bi - rads 3 lesions or mammographic bi - rads 3 microcalcifications ; ( 3 ) accuracy , sensitivity , specificity , positive predictive value ( ppv ) and/or npv was / were measured ; ( 4 ) studies with original data that were published in peer - reviewed journals .
forty - one out of the 52 studies were excluded based on the title . from the 11 remaining studies the abstract or full paper was reviewed .
four studies were excluded because no bi - rads classification was used and 2 studies were reviews .
a computerized search was performed to identify relevant studies in medline and embase up to 2010 .
the following strategy was followed in medline :  magnetic resonance imaging  [ mesh term ] or  magnetic resonance imaging  [ text word ] or  mri  [ text word ] or 
mr imaging  [ text word ] and  probably benign lesions  [ text word ] or  microcalcifications  [ text word ] or  inconclusive findings  [ text word ] and mammography [ mesh term ] or mammography [ text word ] and  sensitivity and specificity  [ mesh term ] or  specificity or sensitivity  [ text word ] . in embase
medline and embase were searched for studies that used breast mri as a problem - solving modality in mammographic bi - rads 3 lesions .
studies were included if the following inclusion criteria were met : ( 1 ) all patients underwent a mammography and breast mri ; ( 2 ) the study population had mammographic bi - rads 3 lesions or mammographic bi - rads 3 microcalcifications ; ( 3 ) accuracy , sensitivity , specificity , positive predictive value ( ppv ) and/or npv was / were measured ; ( 4 ) studies with original data that were published in peer - reviewed journals .
forty - one out of the 52 studies were excluded based on the title . from the 11 remaining studies the abstract or full paper was reviewed .
four studies were excluded because no bi - rads classification was used and 2 studies were reviews .
in the 5 selected studies , 376 breast lesions were reported , of which 213 were microcalcifications , 110 were asymmetric mammographic findings , 36 were non - calcified regular - shaped lesions , 12 were architectural distortion and 5 were scar lesions . in 2 studies , mammographic bi - rads
3 lesions were included ; one only included category 3 lesions , the other also included bi - rads 0 and 4 lesions . in the other 3 studies , mammographic bi - rads 3 microcalcifications were included but microcalcifications that were classified as bi - rads 4 and 5 were also included ( table 1 ) . 

table 1study characteristicsstudy ( first author , year of publication)moy 2009gokalp 2006akita 2009cilotti 2007uetmatsu 2007no . of patients11543535596study designr ,
cp , cnrnrp , cno . of lesions115565055100mammographic findingsasymmetry9812architectural distortion12scar lesion5non - calcified regular - shaped lesions36generalized calcifications7a cluster of tiny calcifications1microcalcifications5055100mammographic bi - rads0781231556923554224125275718gold standardpathologypathology , follow - up 6 monthspathologypathologypathologymammographysensitivity ( % ) nrnr10077nrspecificity ( % ) 80.7nr2459nrppv ( % ) 8.7nrnr6367npv ( % ) nrnrnr7493accuracy ( % ) 78.3nr4467.2nrmrisensitivity ( % ) 1001008573nrspecificity ( % )
91.796.410076nrppv ( % ) 4033.3nr7386npv ( % ) 100100nr7697accuracy ( % ) 92.296.49674.5nrc , consecutive ; nr , not reported ; p , prospective ; r , retrospective.in the analysis of moy et al . , cilotti et al . and uematsu et al .
bi - rads 3 lesions were considered as benign and bi - rads 4 and 5 as malignant.mg+mri .
study characteristics c , consecutive ; nr , not reported ; p , prospective ; r , retrospective . in the analysis of moy et al . , cilotti et al . and
bi - rads 3 lesions were considered as benign and bi - rads 4 and 5 as malignant . in one study ,
the role of mri in the evaluation of mammographic bi - rads 3 lesions was investigated .
mri was performed on 56 lesions described as bi - rads 3 by mammography in 43 patients .
the 56 mammographic bi - rads 3 lesions were distributed into non - calcified regular - shaped lesions ( 64.3% ) , focal asymmetric densities ( 21.4% ) , generalized microcalcifications ( 12.6% ) and a cluster of tiny calcifications ( 1.7% ) . the sensitivity , specificity , accuracy , ppv and npv of mri in the determination of malignancy in these mammographic bi - rads 3 lesions were calculated as 100% , 96.4% , 96.4% , 33.3% and 100% , respectively .
concluded that mri may be helpful in the evaluation of focal asymmetric densities as mri confirmed that 9 of the 12 mammographic focal asymmetric densities were breast tissue and the other 3 were masses .
another study evaluated the usefulness of breast mri in cases of inconclusive mammographic or sonographic findings . in this study , not only mammographic bi - rads 3 lesions ( n  =  15 ) were included but also bi - rads 4 lesions ( n  =  22 ) and mammographic bi - rads 0 lesions ( n  =  78 ) . in total , 115 breast mri scans were used as an adjunctive tool and the findings were correlated with pathology .
the equivocal mammographic findings for which mri was performed were asymmetry without associated microcalcifications ( 85.2% ) , architectural distortion ( 10.4% ) and change in the appearance of the site of a previous benign biopsy finding ( 4.3% ) .
mri had a sensitivity of 100% , npv of 100% and compared with mammography had significantly higher specificity ( 91.7% versus 80.7% , p  =  0.029 ) , ppv ( 40% vs 8.7% , p  =  0.032 ) , and overall accuracy ( 92.2% vs 78.3% , p  =  0.00052 ) .
concluded that breast mri can be a useful adjunctive tool when equivocal findings at conventional mammography are asymmetry or architectural distortion .
three published studies evaluated the role of mri in patients with mammographic bi - rads 3 microcalcifications .
also included mammographic bi - rads 4 microcalcifications and cilotti et al . and uetmatsu et al . included mammographic bi - rads 4 and 5 microcalcifications . in the study of akita et al
. the clinical value of additional breast mri in patients with microcalcifications on mammography and negative ultrasound findings was evaluated .
fifty patients with mammographic microcalcifications ( 9 bi - rads category 3 and 41 bi - rads category 4 ) were included .
mammography had a sensitivity of 100% , a specificity of 24% and an accuracy of 44% , whereas mammography plus mri had a sensitivity of 85% , a specificity of 100% and an accuracy of 96% .
they concluded that breast mri significantly improved the rate of diagnosis of malignancy in breast lesions that were detected as mammographic bi - rads 3 or 4 microcalcifications compared with mammography alone . in the study of uematsu et al .
, breast mri was performed in 100 microcalcifications detected at screening mammography in 96 patients .
ppvs and npvs were calculated on the basis of a bi - rads category and the absence or presence of contrast uptake in the area of microcalcifications .
npv of bi - rads mammography 3 was 93% versus 97% npv of mri ( p  =  0.167 ) .
the ppv of contrast uptake of mri was 86% , which is significantly higher than the 67% ppv of bi - rads mammography 4 and 5 ( p  =  0.033 ) .
concluded that the imperfect ppvs and npvs of mri in the evaluation of microcalcifications detected at screening can not replace stereotactic vacuum - assisted biopsy .
concluded that the ppv and npv of mri in the characterization of microcalcifications are not high . in their study , 55 patients with mammographic calcifications classified as bi - rads categories 3 , 4 or 5 underwent mri and stereotactic vacuum - assisted biopsy .
the sensitivity , specificity , ppv , npv and diagnostic accuracy were 73% , 76% , 73% , 76% and 74.5% , respectively .
their conclusion is that mri can not be considered a diagnostic tool for evaluating microcalcifications .
in one study , the role of mri in the evaluation of mammographic bi - rads 3 lesions was investigated .
mri was performed on 56 lesions described as bi - rads 3 by mammography in 43 patients .
the 56 mammographic bi - rads 3 lesions were distributed into non - calcified regular - shaped lesions ( 64.3% ) , focal asymmetric densities ( 21.4% ) , generalized microcalcifications ( 12.6% ) and a cluster of tiny calcifications ( 1.7% ) . the sensitivity , specificity , accuracy , ppv and npv of mri in the determination of malignancy in these mammographic bi - rads 3 lesions were calculated as 100% , 96.4% , 96.4% , 33.3% and 100% , respectively .
concluded that mri may be helpful in the evaluation of focal asymmetric densities as mri confirmed that 9 of the 12 mammographic focal asymmetric densities were breast tissue and the other 3 were masses .
another study evaluated the usefulness of breast mri in cases of inconclusive mammographic or sonographic findings . in this study , not only mammographic bi - rads 3 lesions ( n  =  15 ) were included but also bi - rads 4 lesions ( n  =  22 ) and mammographic bi - rads 0 lesions ( n  =  78 ) . in total , 115 breast mri scans were used as an adjunctive tool and the findings were correlated with pathology . the equivocal mammographic findings for which mri was performed were asymmetry without associated microcalcifications ( 85.2% ) , architectural distortion ( 10.4% ) and change in the appearance of the site of a previous benign biopsy finding ( 4.3% ) .
mri had a sensitivity of 100% , npv of 100% and compared with mammography had significantly higher specificity ( 91.7% versus 80.7% , p  =  0.029 ) , ppv ( 40% vs 8.7% , p  =  0.032 ) , and overall accuracy ( 92.2% vs 78.3% , p  =  0.00052 ) .
concluded that breast mri can be a useful adjunctive tool when equivocal findings at conventional mammography are asymmetry or architectural distortion .
three published studies evaluated the role of mri in patients with mammographic bi - rads 3 microcalcifications .
also included mammographic bi - rads 4 microcalcifications and cilotti et al . and uetmatsu et al . included mammographic bi - rads 4 and 5 microcalcifications . in the study of akita et al .
the clinical value of additional breast mri in patients with microcalcifications on mammography and negative ultrasound findings was evaluated .
fifty patients with mammographic microcalcifications ( 9 bi - rads category 3 and 41 bi - rads category 4 ) were included .
mammography had a sensitivity of 100% , a specificity of 24% and an accuracy of 44% , whereas mammography plus mri had a sensitivity of 85% , a specificity of 100% and an accuracy of 96% .
they concluded that breast mri significantly improved the rate of diagnosis of malignancy in breast lesions that were detected as mammographic bi - rads 3 or 4 microcalcifications compared with mammography alone . in the study of uematsu et al .
, breast mri was performed in 100 microcalcifications detected at screening mammography in 96 patients .
ppvs and npvs were calculated on the basis of a bi - rads category and the absence or presence of contrast uptake in the area of microcalcifications .
npv of bi - rads mammography 3 was 93% versus 97% npv of mri ( p  =  0.167 ) .
the ppv of contrast uptake of mri was 86% , which is significantly higher than the 67% ppv of bi - rads mammography 4 and 5 ( p  =  0.033 ) .
uematsu et al . concluded that the imperfect ppvs and npvs of mri in the evaluation of microcalcifications detected at screening can not replace stereotactic vacuum - assisted biopsy .
concluded that the ppv and npv of mri in the characterization of microcalcifications are not high . in their study , 55 patients with mammographic calcifications classified as bi - rads categories 3 , 4 or 5 underwent mri and stereotactic vacuum - assisted biopsy .
the sensitivity , specificity , ppv , npv and diagnostic accuracy were 73% , 76% , 73% , 76% and 74.5% , respectively .
their conclusion is that mri can not be considered a diagnostic tool for evaluating microcalcifications .
the ahrq guideline states that the work - up for mammographic bi - rads 3 lesions should be biopsy or follow - up imaging after 6 months .
there is not yet a role for breast mri , because ultrasonography- or mammography - guided core or vacuum biopsy can obtain histological proof of a bi - rads 3 lesion .
a variety of minimally invasive procedures are widely available , relatively safe , inexpensive and provide a diagnosis without surgical intervention .
furthermore , breast mri has its limitations , which include higher costs , longer examination time , and lower availability compared with mammography and ultrasound .
if breast mri is to be an effective addition to the work - up of a mammographic bi - rads 3 lesion , the npv of breast mri must be sufficiently high to definitively rule out further work - up with biopsy . although there were only 5 studies that investigated the usefulness of mri as a problem - solving modality in mammographic bi - rads 3 lesions , the npv was 100% in non - calcified mammographic bi - rads 3 lesions and 7697% in mammographic bi - rads 3 microcalcifications .
on the other hand , kuhl indicated that the evidence for the effectiveness of breast mri is relatively weak in helping to solve mammographic problems , because in a multicenter trial of bluemke et al .
the npv was not high enough to exclude malignancy with sufficient confidence in the case of an equivocal or suspicious lesion seen at conventional imaging .
the diagnostic accuracy of mri was studied in 821 patients with a suspicious mammographic bi - rads 4 or 5 lesion ( 85% ) or a suspicious clinical finding with a negative or benign conventional work - up ( 15% ) before biopsy .
mri had an npv of 85% with cancer missed in 48 of 329 negative mri examinations .
this npv is not sufficiently high to avoid biopsy in suspicious mammographic bi - rads 4 or 5 lesions .
this widely referenced multicenter study was performed in 14 hospitals from 1998 to 2001 and therefore used now outdated mr equipment .
furthermore , the study of bluemke et al . included patients with microcalcifications of the breast , which have a negative influence on the npv . in this meta - analysis , 3 studies assessed the role of mri in mammographic bi - rads 3 microcalcifications .
therefore , mri can not be implemented as a problem - solving modality in mammographic microcalcifications at this time .
mri can be useful as an additional tool in patients with calcifications ; it can be helpful in demonstrating or excluding underlying invasive cancer , because mri has a high npv for invasive cancer .
an important application of mri in patients with associated with suspicious microcalcifications could be to evaluate disease extension .
however , the studies that comply with the inclusion criteria of the meta - analysis , i.e. non - calcified mammographic bi - rads 3 lesions , reported an npv of 100% and concluded that mri can be a useful tool in mammographic bi - rads 3 lesions , especially when mammographic findings are asymmetry or architectural distortion .
although there are sparse data , the first solid data indicate that breast mri might be useful as a problem - solving modality to exclude patients with non - calcified mammographic bi - rads 3 lesions from further diagnostic work - up .
 abstractthe probability of a mammographic breast imaging reporting and data system ( bi - rads ) 3 lesion being cancer is considered to be less than 2% . 
 therefore , the work - up of a mammographic bi - rads 3 lesion should be biopsy or follow - up mammography after 6 months . however , most patients referred for biopsy have benign disease . although the negative predictive value ( npv ) of magnetic resonance imaging ( mri ) is highest of all imaging techniques , it is not yet common practice to use breast mri as a problem - solving modality to exclude patients for further diagnostic work - up . therefore , in this meta - analysis the usefulness of breast mri as a problem - solving modality in mammographic bi - rads 3 lesions is investigated . after a systematic search only 5 out of 61 studies met the inclusion criteria . 
 the npv in 2 of those studies was reported to be 100% . 
 it was concluded that mri can be used as an adjunctive tool to mammographic bi - rads 3 findings to exclude patients for further diagnostic work - up . 
 the other 3 studies assessed the accuracy of mri in mammographic bi - rads 3 microcalcifications . 
 these studies reported an npv of mri between 76% and 97% . 
 therefore , mri can not be implemented as a diagnostic tool to evaluate mammographic microcalcifications at this time . 
 the first solid data indicate that breast mri might be useful as a problem - solving modality to exclude patients with non - calcified mammographic bi - rads 3 lesions for further diagnostic work - up . 
 however , further research is needed to verify these results . 