Categorical Classification of Spiculated Mass on Breast MRI

Transcription

1 Categorical Classification of Spiculated Mass on Breast MRI Poster No.: C-1974 Congress: ECR 2013 Type: Authors: Scientific Exhibit Y. Kanda 1, S. Kanao 2, M. Kataoka 2, K. Togashi 2 ; 1 Kyoto City/JP, 2 Kyoto/JP Keywords: DOI: Cancer, Diagnostic procedure, MR, Breast /ecr2013/C-1974 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 13

2 Purpose Breast MRI is the most sensitive imaging modality to detect malignancy. In the 21 st century, some guidelines for breast MRI (European Society of Breast Imaging, American College of Radiology and so on) are established. Lexicon and reporting system of Breast MRI are defined by Breast Imaging- Reporting and Data System (BI-RADS) MRI. According to BI-RADS MRI, tumor margin can be described as smooth, irregular, or spiculated. And also, category 5 is defined as positive predictive value (PPV) more than 95%. In practice, spiculated margins frequently are a feature of malignant breast lesions but we sometimes experience benign speculated lesions such as radial scar. Low PPV may lead to improper clinical management. Improvement of PPV is one of the important issues for breast MRI. The purpose of this study was to correlate imaging findings of spiculated mass on breast MRI with pathology and to improve the accuracy of those lesions for meeting the criteria of category 5 (positive predictive value: PPV more than 95%.) Methods and Materials Study population This study was approved by institutional review board and general informed consent was acquired by all subjects enrolled. We retrospectively reviewed 1135 cases of breast MRI in our institution, and picked up 114 cases which were reported as spiculated mass. Cases without contrast enhancement and those after pre-surgical systemic therapy were excluded. MRI protocol MRI was acquired with a 3 T scanner (Magnetom Trio Tim; Siemens Medical Solutions, Erlangen, Germany) with a breast-dedicated 16-channel coil. After getting pre-contrast axial T2-weighted, T1-wighted and diffusion-weighted images, fat-suppressed T1- weighted dynamic images were acquired once before and three times after Gadolinium infusion. At 0-1, 1-2 and 5-6 min after injection. The whole breasts were scanned in high temporal resolution of 1 min (3D-VIBE: TR/TE 3.8/1.5 ms, FA 15, FOV 330 mm 330 mm, matrix , 1 mm thickness, 144 slices) in axial orientation. At 2-5 min, a scan was conducted with high spatial resolution (3D-VIBE: TR/TE 4.0/1.6 ms, FA 15, FOV 330 mm 330 mm, matrix , 0.8 mm thick, 176 slices) in coronal orientation. Page 2 of 13

3 Infused Gadolinium contrast materials were either Gadoteridol (ProHance, Eisai Inc., Tokyo, Japan) for patients under or equal to 60 kg, or Gadodiamide (Omniscan, Daiichi- Sankyo Inc., Tokyo, Japan) for patients over 60 kg, with a dose of 0.2 ml/kg power injected at the speed of 2.0 ml/s and flashed with 20 ml of saline at the same rate. These two contrast agents were reported to have similar contrast effect. Image analysis Images were analyzed using 3D workstation (Aquarius Net, TeraRecon Inc. Tokyo Japan). Evaluation was conducted without the information of pathology by an experienced radiologist with 10-year experience in breast MRI examination. Tumor shape, internal enhancement characteristics and enhancement kinetics patterns were evaluated by lexicon of BI-RADS MRI. Tumor size was measured by longest diameter using multiplanar reformation. Pathological and statistical analysis All studies were pathologically diagnosed by surgery or needle biopsy. Statistical analysis was performed using statistical software (Excel statistics version SSRI, Tokyo, Japan). The analysis proceeded in two steps: First, the PPV of each imaging characteristic of interest was estimated as the proportion of all known cases with cancer among those who exhibited the particular characteristic at initial MR imaging. And second, exact 95% confidence intervals (CIs) were calculated for each PPV estimate. Results Among 114 cases, 107 cases (93.9%) were malignant and 7 cases (6.1%) were benign. Overall PPV of spiculated mass was 93.9%. Individual diagnoses of malignant cases were as follows: invasive ductal carcinoma (97 cases), invasive lobular carcinoma (8 cases) and ductal carcinoma in situ (2 cases). Those of benign cases were as follows: radial scar/ complex sclerosing lesion (2 cases), papilloma or ductal adenoma (2 cases), sclerosing adenosis, granulomatous mastitis and granular cell tumor. Malignant lesions were significantly larger than benign lesions (22.6 vs.9.8mm, p<0.001). PPVs of cases with 0-10mm, 10-20mm and 20- mm were 70.6% (95CI: %), 95.9% (95CI: %) and 100% respectively (Figure 1) No significant correlations were observed between contrast kinetics, shape or internal enhancement pattern and pathology (Table 1). We show the benign cases with spiculated margin (Figure 2-6). Page 3 of 13

4 Images for this section: Page 4 of 13

5 Page 5 of 13

6 Table 1: Enhancing Pattern of Benign/Malignant Lesions * n.s. ; non significant Fig. 1: Size-Specific Number of Case Page 6 of 13

7 Fig. 2: This is an example case of benign mass with spiculation. A women in her 40s presented to the clinic with abnormal finding in screening mammography. Mammography shows disturbed structure in left M area(fig 2), category4. Ultra sound study shows 9mm hypoechoic lesion and was diagnosed category 3 (Fig 3). Core needle biopsy (CNB) was performed and diagnosed invasive ductal carcinoma. The patient was referred to our hospital and underwent MRI. In MRI study, 9mm mass was found in left A area, and showed irregular shape, spiculated margin, rim enhancement, rapid/washout pattern, category 6. CNB was also performed in our hospital and suspected benign. Page 7 of 13

8 Incisional biopsy was performed and final pathological diagnosis was Radial Scar/ Complex Sclerosing Lesion with no malignant findings (Fig 6). Fig. 3: This is an example case of benign mass with spiculation. A women in her 40s presented to the clinic with abnormal finding in screening mammography. Mammography shows disturbed structure in left M area(fig 2), category4. Ultra sound study shows 9mm hypoechoic lesion and was diagnosed category 3 (Fig 3). Core needle biopsy (CNB) was performed and diagnosed invasive ductal carcinoma. The patient was referred to our hospital and underwent MRI. In MRI study, 9mm mass was found in left A area, and showed irregular shape, spiculated margin, rim enhancement, rapid/washout pattern, category 6. CNB was also performed in our hospital and suspected benign. Incisional biopsy was performed and final pathological diagnosis was Radial Scar/ Complex Sclerosing Lesion with no malignant findings (Fig 6). Page 8 of 13

9 Fig. 4: This is an example case of benign mass with spiculation. A women in her 40s presented to the clinic with abnormal finding in screening mammography. Mammography shows disturbed structure in left M area(fig 2), category4. Ultra sound study shows 9mm hypoechoic lesion and was diagnosed category 3 (Fig 3). Core needle biopsy (CNB) was performed and diagnosed invasive ductal carcinoma. The patient was referred to our hospital and underwent MRI. In MRI study, 9mm mass was found in left A area, and showed irregular shape, spiculated margin, rim enhancement, rapid/washout pattern, category 6. CNB was also performed in our hospital and suspected benign. Incisional biopsy was performed and final pathological diagnosis was Radial Scar/ Complex Sclerosing Lesion with no malignant findings (Fig 6). Page 9 of 13

10 Fig. 5: This is an example case of benign mass with spiculation. A women in her 40s presented to the clinic with abnormal finding in screening mammography. Mammography shows disturbed structure in left M area(fig 2), category4. Ultra sound study shows 9mm hypoechoic lesion and was diagnosed category 3 (Fig 3). Core needle biopsy (CNB) was performed and diagnosed invasive ductal carcinoma. The patient was referred to our hospital and underwent MRI. In MRI study, 9mm mass was found in left A area, and showed irregular shape, spiculated margin, rim enhancement, rapid/washout pattern, category 6. CNB was also performed in our hospital and suspected benign. Incisional biopsy was performed and final pathological diagnosis was Radial Scar/ Complex Sclerosing Lesion with no malignant findings (Fig 6). Page 10 of 13

11 Fig. 6: This is an example case of benign mass with spiculation. A women in her 40s presented to the clinic with abnormal finding in screening mammography. Mammography shows disturbed structure in left M area(fig 2), category4. Ultra sound study shows 9mm hypoechoic lesion and was diagnosed category 3 (Fig 3). Core needle biopsy (CNB) was performed and diagnosed invasive ductal carcinoma. The patient was referred to our hospital and underwent MRI. In MRI study, 9mm mass was found in left A area, and showed irregular shape, spiculated margin, rim enhancement, rapid/washout pattern, category 6. CNB was also performed in our hospital and suspected benign. Incisional biopsy was performed and final pathological diagnosis was Radial Scar/ Complex Sclerosing Lesion with no malignant findings (Fig 6). Page 11 of 13

12 Conclusion It has been obvious that categorical PPV of small sized (lower than 5mm) mass in MRI is low. In our study, the correlation between size and malignancy was also revealed. We sometimes cannot recognize masses less than 5mm as a spiculation. Thus, we set the cut off line at 10 mm. At a morphologic point of view, categorical PPV was highly marked for those with central enhancement or internal septation. These morphologic patterns are usually cannot be seen in small sized masses. And that is part of why small sized masses have lower PPV. Also, all study including benign cases showed rapid and washout/plateau pattern in dynamic study. Therefore, dynamic enhancement pattern was not useful for differential diagnosis. We concluded that it would be appropriate to categorize spiculated mass less than 10mm as category 4 and more than 10mm as category5. Our result suggests that lesion size is a useful finding and speculated masses on breast MRI should be classified as category 5 for lesions over 10mm in size, and classified as category 4 for smaller lesions. At a morphologic point of view, categorical PPV was highly marked for those with central enhancement or internal septation. These morphologic patterns are usually cannot be seen in small sized masses. And that is part of why small sized masses have lower PPV. Also, all study including benign cases showed rapid and washout/plateau pattern in dynamic study. Therefore, dynamic enhancement pattern was not useful for differential diagnosis. We concluded that it would be appropriate to categorize spiculated mass less than 10mm as category 4 and more than 10mm as category5. Our study has some limitations. Only one radiologist diagnosed all the study. The way how we measured spiculated mass could give a bias to our result. When we measure a mass, we didn't include liner lesion of spiculated mass.(fig 3) If we measure a mass at a largest margin within liner lesion, the result would possibly be different. It has been said that categorical PPV of small sized (lower than 5mm) mass in MRI is low. Harms et al 1) indicated that biopsy was recommended only for MRI-detected lesions 1cm or larger, but no deta validated this approach. Laura 2) described that MRI lesion size may be useful in predicting the likelihood of malignany in MRI-detected breast leasions. They have observed the all lesion with or without spiculations. Page 12 of 13

13 References 1) MR imaging of the breast with rotating delivery of excitation off resonance: Radology : #Does Size Matter?#Positive Predictive Value of MRI-Detected Breast Lesions as a Function of Lesion Size AJR : Personal Information Page 13 of 13