however , it is difficult to target the exact site of a microcalcification or non - palpable breast lesion if it is not detectable by ultrasound . because stereotactic vacuum - assisted breast biopsy ( vab ) has a higher accuracy rate using a horizontal ( x ) , vertical ( y ) , and depth ( z)-axis compared with ultrasound - guided vab for breast microcalcification or non - palpable lesions , it has been used as a reliable technique to localize and sample those breast lesions . furthermore , if the targeting is successful , it is easier than ultrasound - guided vab or surgical biopsy . however , an expensive , dedicated prone table is necessary to perform prone - positioned stereotactic vab . additionally , there are some limitations to upright stereotactic vab , such as inconvenience or a vasovagal reaction of patients . although the lateral decubitus position is an alternative position for stereotactic vab , the breast lesion often moves in the lateral decubitus position , as identified in cranio - caudal ( cc ) or mediolateral - oblique ( mlo ) mammography views . therefore , a true lateral mammography view is needed to overcome this problem , which is nearly identical to stereotactic mammography in a lateral decubitus position . we used the lateral decubitus position during stereotactic vab combined with true lateral mammography on 15 patients . between january and june 2010 , we performed stereotactic directional vab on 15 patients at the breast cancer center of pusan national university hospital . in all cases , the cc and mlo mammography planes were preferentially reviewed to identify non - palpable lesions with or without microcalcifications , and those lesions were classified according to the breast imaging reporting and data system ( bi - rads ) . true lateral views of the mammographic images ( ge medical systems , milwaukee , usa ) were obtained in all cases before lateral decubitus positioning for stereotactic vab . the patient laid on a stereotactic vab table ( digital stereotaxy with senographe ds interventional ; ge medical systems ) in the lateral decubitus position with the breast lesion facing up ( figure 1 ) . the scout view and 15 paired stereotactic mammography were performed to localize the breast lesion , which was compared with a true lateral view ( figure 2 ) . we calculated the horizontal ( x ) and vertical ( y ) distanced and the depth ( z ) from the zero point of the stereotactic vab device . local anesthesia was performed with 2 ml of a 2% lidocaine injection under aseptic conditions . stereotactic 15 paired mammographic views were obtained again after an 8-gauge vab probe ( mammotome ; ethicon - endosurgery , cincinnati , usa ) was inserted to verify the site where the microcalcification was located . the needle position was corrected when the distance was more than 2 mm between the needle tip and the breast lesion . each of two breast tissue specimens were collected from six clockwise directions ( 2 , 4 , 6 , 8 , 10 , and 12 o'clock ) and arranged in a regular sequence on a petri dish containing round filter paper ( figure 3 ) . the stereotactic vab was concluded when the breast lesion was identified by specimen mammography in more than two breast tissues . additional sampling was performed when the breast lesion was still identified on stereotactic mammography or was not identified in specimen mammography . a post - procedure mammography view was obtained after a breast marker clip ( johnson & johnson , ethicon - endosurgery , cincinnati , usa ) was inserted . the breast was manually compressed at the procedure table . only a piece of strip envelope ( steri - strip ; 3 m , st . microcalcifications were observed in 12 ( 80.0% ) of the 15 cases , and the remaining three cases ( 20.0% ) showed non - palpable breast masses . eight cases ( 53.3% ) were classified as bi - rads category 3 and seven ( 46.7% ) were category 4 ( table 1 ) . the morphological characters of the microcalcifications were scattered punctuate ( n=5 ) , clustered punctuate ( n=4 ) , amorphous ( n=2 ) and pleomorphic ( n=1 ) . non - palpable masses without microcalcifications were spiculated ( n=2 ) and oval shape ( n=1 ) . microcalcification clusters were 6 - 15 mm in diameter ( mean , 10.3 mm ) and masses were 6 - 8 mm in diameter ( mean , 6.7 mm ) ( table 2 ) . the mean patient age was 45.7 years ( range , 33 - 63 ) . ten cases of microcalcifications were identified in the first specimen mammographic image , and the breast marker clip was located accurately in two cases of non - palpable masses after one procedure . the mean procedure time was approximately 30.1 minutes , and the average number and length of obtained core tissues was 14.4 ( range , 9 - 26 ) and 2.7 cm ( range , 0.8 - 3.3 ) , respectively . no patient developed a vasovagal reaction such as nausea , vertigo , or syncope during the procedure . one week after the procedure , complications were identified by a physical examination and ultrasound . a minimal hematoma was observed in two cases ( 13.3% ) , which resolved spontaneously ( table 3 ) . in the histopathologic diagnoses of the stereotactic vab , 14 cases had benign breast lesions and 1 case was a ductal carcinoma in situ ( dcis ) . additional breast conserving surgery ( quadrantectomy with a local flap ) was performed for the malignant case . among 12 cases of microcalcification on mammography , the microcalcification was confirmed in 11 ( 91.7% ) by the pathological findings of normal stroma , benign ductules , fibrocystic changes , or dcis . three cases without microcalcification on mammography were confirmed as sclerotic stroma with benign breast tissue . fibroadenomas were identified in two cases , which were combined with fibrocystic changes and microcalcification ( table 4 ) . stereotactic breast biopsy is a reliable procedure for localizing and sampling of breast tissue using mammography . stereotactic vab has a high sensitivity ( 98% ) and specificity ( 100% ) and may provide a promising alternative to open breast biopsy [ 1,8 - 12 ] . among various type of stereotactic breast biopsy , stereotactic vab is indicated for microcalcifications or non - palpable breast lesions not detectable by ultrasound . bi - rads categories 3 or 4 for non - palpable breast lesions are usually applied for stereotactic breast biopsy , because category 5 or higher cases should be submitted to ultrasound - guided needle biopsy . stereotactic vab is a very consistent and easy procedure if the needle is well located when targeting the breast lesion . because accurate targeting is key for stereotactic vab , the needle should be inserted at the exact site of the calculated x , y , and z - axis points from the zero point , which is set in the vab machine . furthermore , the complication rates for stereotactic vab are relatively lower than ultrasound - guided vab , because less breast tissue is collected . the failure rate for stereotactic vab is 3 - 10% , mostly due to a difficult procedure site or a complication such as a lesion near the skin , muscle or axilla . in our study , we did not encounter a case in which we could not use stereotactic vab , and a surgical operation was added only for a malignant lesion . because no further procedures were performed for the other 14 benign lesions , the sensitivity and specificity of stereotactic vab could not be evaluated . a limitation of stereotactic vab is that less breast tissue volume is obtained than with ultrasound - guided vab . the procedure completion time for stereotactic vab is usually not indicated in studies and no definite guideline exists . we terminated the procedure when microcalcifications were seen in more than two tissues obtained for specimen mammography or when the breast marker clip was accurately located at a breast lesion on post - procedure mammography . because stereotactic vab focuses on diagnosis and not treatment , but , the rate of atypical ductal hyperplasia ( adh , 20.9% ) or dcis ( 11.2% ) can be underestimated . therefore , identifying an adh or dcis during stereotactic vab warrants a further procedure or surgical excision . although stereotactic vab is definitely an innovative diagnostic procedure , its disadvantages are that it is conducted in a prone position and that the unit is very large and expensive ( approximately quadruple that of a regular unit ) . it is also difficult to perform stereotactic vab when the targeting site is close to the pectoralis muscle , axilla , or skin . in contrast , stereotactic vab in an upright position allows the breast lesion to be easily found with a scout image , which is almost same as the cc plane of original mammography . however , it is very difficult to maintain a stable position , because transient neck and back pain , as well as body numbness are common during the procedure , especially in the elderly . moreover , patients can see the sharp devices , the wound and even blood , which cause anxiety , emotional stress , and possibly a vasovagal reaction , such as nausea , vertigo , or syncope . to compensate for the disadvantages of the prone or upright - positioning for stereotactic vab , a one - side decubitus position was used , which is more comfortable and stable for the patients , even if it has not been generally used . an expensive prone table is unnecessary for lateral positioning during stereotactic vab and it causes neither a vasovagal reaction nor neck , or back pain . but , it is more difficult to detect the breast lesion , because the lesions often moves , which is different from standard mammography . to alleviate this problem , we performed a true lateral mammography view before the procedure , which lengthened the procedure . breast lesions could be easily identified on stereotactic mammography , because the targeted site was nearly the same as the pre - procedure true lateral view mammography . our report has limitations such as the small number of cases with a short term follow - up and the absence of a comparison between stereotactic vab and other diagnostic procedures . according to several studies , 6 - 27% of benign breast lesions remain after a vab procedure , and it is difficult to distinguish between a post - procedural scar and residual lesion within 6 months . therefore , long term follow - up is necessary to evaluate for a residual breast lesion . although this report has simply introduced a diagnostic procedure , the usefulness of lateral decubitus positioning for stereotactic vab with true lateral mammography could be verified if a comparison between stereotactic vab and open biopsy or ultrasound - guided vab with a long term follow - up result was added .
stereotactic vacuum - assisted breast biopsy ( vab ) has been used to evaluate microcalcifications or non - palpable breast lesions on mammography . 
 although stereotactic vab is usually performed in a prone or upright position , an expensive prone table is necessary and vasovagal reactions often occur during the procedure . for these reasons , 
 the lateral decubitus position can be applied for stereotactic vab , and true lateral mammography can be used to detect the lesion . 
 we report on 15 cases of lateral decubitus positioning for stereotactic vab with true lateral mammography for non - palpable breast lesions or microcalcifications . 
 the mean procedure time was approximately 30.1 minutes , and no complications occurred during the procedures . 
 fourteen cases had benign breast lesions and one case had a ductal carcinoma in situ . 
 the lateral decubitus stereotactic vab with true lateral mammography can be applied for microcalcifications or non - palpable breast lesions and helps to minimize anxiety and vasovagal reactions in patients .