Accuracy of sonography BIRADS lexicon

Transcription

1 Accuracy of sonography BIRADS lexicon Poster No.: C-0255 Congress: ECR 2011 Type: Authors: Keywords: DOI: Scientific Paper N. Ahmadinejad, S. Pourjabbar, M. Shakiba, A. Imanzadeh; Tehran/IR Breast, Obstretric imaging, Oncology, Ultrasound, Biopsy /ecr2011/C-0255 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 9

2 Purpose Breast cancer is the most common malignancy in women.(1) More than cases are diagnosed each year and women die annually from this cancer. (1) By invention of high resolution sonographic probes and new advances in the corresponding technology, ultrasound speculated as a complementary to mammography in assessing breast lesions. It has been helpful in diagnosis of up to 27% of mammographically occult lesions. (2,3) In 2003, the American college of radiology (ACR) introduced Breast Imaging Report and Data system (BIRADS) for ultrasound. (4,5) The ACR has suggested that each lesion entitles into a single BIRADS category and undergo the appropriate recommendations. (6,7) The possibility of malignancy in each category became a field of interest soon after the appearance of BIRADS Lexicon and as a result, it has been tested in several studies. (2, 8, 9) In the present study, we are going to assess the diagnostic efficacy of BIRADS lexicon [in terms of diagnostic indices including sensitivity, specificity and predictive values] in high US BIRADS scores [3,4 and 5 scores]. Methods and Materials Files of all the women who referred to our department between were retrospectively studied. They were referred by physicians for either primary or complementry evaluations by sonography.150 had lesions with mammographic or sonographic BIRADS III, IV and V and recommended for further investigations. The patients were recommended the plan according to ACR guidelines (Table 1) and totally, documents 108 of them that accepted to undergo core needle biopsy via sonography were available and reviewed. Data on BIRADS descriptors, associated findings, BIRADS category and pathology reports were gathered. Descriptors were the same as ACR lexicon. (7) Our device was an ultrasonic XP with multifrequency probe; the biopsies were taken by an automatic 14 gauge needle. Sensitivity, specificity and accuracy, PPV (Positive Predictive Value) and NPV (Negative Predictive Value), PLR (Positive Liklihood Ratio)and NLR(Negative Likelihood Ratio) of US were evaluated.we calculataed these indices in three different situations: first when we considered BIRADS 4 and 5 as malignancy, second when BIRADS 4b and 5 were considered as malignancy and finally, when only BIRADS 5 was considered as malignancy.accordingly, the ROC analysis using ROC-fit technique was performed and the area under the curve,[auc], standard deviation Page 2 of 9

3 and p-value for ROC curve and the AUC were calculated. As the study was retrospective and the procedure done was part of the diagnosis, no ethical problem was encountered. BIRADS Category Risk of Malignancy Management 1 Normal 0 Clinical lump follow up & screening 2 Benign Finding 0 Clinical lump follow up & screening 3 Probabely Benign # 2% Patient choice: follow up versus biopsy 4a Mildly Suspicious 2% - 50% Biopsy 4b Moderately Suspicios 50% - 90% Biopsy 5 Malignant # 90% Biopsy Results Our patients were between 18 to 75 years old with the mean age of 43.9 ±11.5 years old. We found 98 masses, 4 cysts and 6 lesions in the form of focal tissue thickening. 49 lesions categorized as sonographic BIRADS III, 19 as IVa,18 as IVb and 22 as V. It was an age difference between BIRADS groups though it was not significant. Histological reports of all the 108 lesions were obtained. 78(72.2%) reported as benign and 30 (27.8%) lesions as malignant. In benign lesions 35 were fibradenoma. Details on benign lesions are shown in table 1. Table 1: Pathologic reports of benign lesions Benign Lesions Fibroadenoma 35 Typical Ductal Hyperplasia Fibrocystic Changs 16 Fibro adipose Tissue Intraductal Papiloma Sclerosing Adenosis 10 Cholestrol GranulommaRadial 5 Tension Cyst Page 3 of 9

4 Fat Necrosis 4 Sclerosing Lesion 1 Rate of malignancy finding was 2% in category 3, zero in category 4a, 50% in category 4b and 90.9% in category 5 of BIRADS.Thus among 59 suspicious lesions [patients with category 4 & 5], 29 (49.1%) were malignant in histology. The receiver operating curve (ROC) analysis was done for BIRADS. As the BIRADS is an ordinal variable, we can't do the classic ROC analysis thus we did a smooth ROC technique for this purpose using mentioned three cut of points. After the analysis, we yielded an area under the curve of 0.96 (CI= ) (p-value=0.187). [figure1] Considering BIRADS 4 and 5 as malignancy, we yielded the sensitivity and specificity of 0.97 and 0.62 respectively. These figures were 0.97 and 0.86 when we considered BIRADS 4b and 5 as malignancy and were 0.67 and 0.97 when we considered only BIRADS 5 as malignancy. Details are shown in Table 2. Table 2:Three different BIRADS cut points 3 vs. (4,5) 0.97 (CI = ) (3,4a) vs. (4b,5) Sensitivity Specificity PPV NPV PLR NLR (CI= (CI= ) ) (3,4) vs (CI ) (CI= ) ( ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) (CI= ) Images for this section: Page 4 of 9

5 Fig. 1 Page 5 of 9

6 Conclusion Nowadays US is considered as a complementary modality where mammography is not responsive enough. Non-palpable or small breast lesions can now be detected by new ultrasound devices; meanwhile, it offers a more comfortable and convenient way to provide guidance in interventional breast procedures while it is not invasive. (10) According to Stavros, any lesion with neither powerful imaging finding in favor of malignancy nor benignity will be categorized as BIRADS 4. (6) The probability of malignancy in BI-RADS 4 lesions ranges from 2% to 95% (11). As a result, there is a considerable percentage of both malignant and benign lesions in this category. This fact urges implementation of sub categorization of imaging findings for better differentiation of malignant lesions in this class. Back to figure 1, high value of AUC shows that the BIRADS lexicon has a good efficiency in differentiating of breast lesions, although the relatively borderline insignificant P-value (0.18) for smooth ROC may be due to small sample size of our study. It might be concluded from the curve that the second defined cut point [which consider 3 and 4a lesions as benign], has a better efficacy as a whole, considering sensitivity and specificity together comparing to the other two. In table 4, we see a NLR of 25.8 in the second group which is in favor of our conclusion. Presence of malignancy in each BIRADS category in our study is approximately in line with other studies (12) and also comparable to mammography surveys. (Table 4) Table 4- Rate of malignancy finding in each BIRADS category References Mammography Studies BIRADS Category Lorenzen et al Liberman et al Mendez et al Orel et al B erub e et al Sonography Studies Heinig et al Present Study Page 6 of 9

7 Being strict about the categorization will increase the false positive and demonstrate a low rate of malignancy in category 4a. It seems that the BIRADS approach is somehow stringent. Presence of features not in favor of benignity shift the BIRADS score from 3 to higher scores. Although this approach is enough conservative and makes a very low missing rate on malignant lesions (high sensitivity), but it makes a relatively high rate of unnecessary invasive procedures on benign lesions too. Based on our results, It could be proposed that moving the decision cut point from [3-4] to [4a-4b] reduces the unnecessary biopsies (improving specificity) without any loosing of malignant lesions (the same sensitivity for both). BIRADS 4a lesions are usually ones which do not show all the characters designated to benignity, however, there are some confounders such as age or positive family history of malignancy,which although are not defined in BIRADS lexicon but somehow lead the radiologist to assign BIRADS 4a instead of BIRADS3. Moreover, when more than three lobulations are present in the margin of the lesion, fibroadenoma is the likeliest cause but the rate of malignancy is slightly increased also.(6) These factors might lead us to have a zero percent of malignancy in our BIRADS 4a group. In the sonography algorithm any lesion which is thought to be a fibradenoma or intraductal papilloma but does not fulfill strict criteria of benignity is nominated for BIRADS4a. According to our study, changing current guidelines for biopsy seems probable as presence of some situations such as above mentioned factors that changed the BIRADS category to 4a could be considered as non significant findings that do not increase the rate of malignancy. Thus we can reserve the biopsy for BIRADS greater than 4a. Of course, revision of the guidelines should be done very cautiously based on studies on large series of the patients and after doing comprehensive efficiency studies that carefully evaluate the trade off of reducing breast biopsy versus missing cancerous lesions. At last we may suggest that considering BIRADS 4a lesions as benign, results in a greater specificity, PPV,PLR and NLR and helps in reducing unnecessary biopsies; though the study should be done on greater sample size in order to prove our findings. References 1-Marie Tartar, Christopher E. Comstock,Michael S. Kipper,Breast Cancer Imaging, A Multidisciplinary, Multimodality approach,. Mosby-ELSEVIER 2008 Page 7 of 9

8 2- Hong AS, Rosen EL, Soo MS, Baker JA. BI-RADS for sonography: positive and negative predictive values of sonographic features. AJR Am J Roentgenol 2005; 184: Hille H, Vetter M, Hackeloer BJ. Re-evaluating the role of breast ultrasound in current diagnostics of malignant breast lesions. Ultraschall Med 2004; 25: Levy L, Suissa M, Chiche JF, Teman G, Martin B, BIRADS ultrasonography,eur J Radiol Feb;61(2): Epub 2007 Jan 9 5- American College of Radiology. BI-RADS: ultrasound. In: Breast Imaging Reporting and Data System: BI-RADS Atlas (4th edn). American College of Radiology: Reston, VA, Stavros A. Thomas, Breast Ultrasound, 2004,By Lippincott Williams and Wilkins 7- American College of Radiology.BI-RADS US, First Edition 2003, 8 - Rahbar G, Sie AC, Hansen GC, Prince JS, Melany ML,Reynolds HE, Jackson VP, Sayre JW, Bassett LW. Benign versus malignant solid breast masses: US differentiation. Radiology 1999; 213: Stavros T, Thickman D, Rapp CL, Dennis MA, Parker SH, Sisney GA. Solid breast nodules: use of sonography to distinguish between benign and malignant lesions. Radiology 1995; 196: See-Ying Chiou,Yi-Hong Chou,Hong-Jen Chiou,Hsin-KaiWang, Chui-Mei Tiu,Ling- Ming Tseng, Cheng-Yen Chang, Sonographic features of nonpa;pable breast cancer: A study based on ultrasound-guided wire-localized surgical biopsies, Ultrasound in Med. & Biol., Vol. 32, No. 9, pp , D'Orsi CJ, Bassett LW, Berg WA, et al. Mammography. In: Breast Imaging Reporting and Data System (BI-RADS). 4th ed. Reston, Va: American College of Radiology, J. HEINIG, R. WITTELER, R. SCHMITZ, L. KIESEL and J. STEINHARD, Accuracy of classification of breast ultrasound findings based on criteria used for BI-RADS, Ultrasound Obstet Gynecol 2008; 32: Page 8 of 9

9 Personal Information Page 9 of 9