Mammography, Ultrasonography, MRI And ¹⁸F-FDG PET-CT In Detecting The Primary Breast Malignancy Of Patients Initially Presenting As Axillary Metastasis

Objective: To analyze the mammography, ultrasonography, MRI and 18F-FDG PETCT findings in patients with axillary lymph node metastases with no palpable mass in the breast, to compare mammography, ultrasonography, MRI and 18F-FDG PET-CT in identifing primary occult breast carcinoma.Materials and Methods: This retrospective study evaluated 73 women with axillary lymph node metastases with no palpable mass in the breast who underwent breast MRI between Jan 2005 to Nov 2014. Among them, 61 patients had mammography examination, 69 patients had ultrasonography examination, 19 patients had MRI-directed Sonography examination, 22 patients had 18F-FDG PET-CT examination. According to the lexicon of Breast Imaging Reporting and Data System(BI-RADS) designed by American College of Radiology(ACR), including morphology, margin and density of mass, morphology and distribution of microcalcification and focal asymmetry on mammography, morphology, echo pattern and posterior features of mass, calcifications, associated features including architectural distortion, duct changes and vascularity on ultrasonography, morphology or distribution, internal enhancement characteristics, Time intensity curve on MRI. Two senior nuclear medicine physicians with more than 5 years of experience reviewed all 18F-FDG PET-CT images. The positive lesions uptake higher than that of the neaeby normal tissue. The maximum standardardized uptake value(SUVmax) of the positive lesions was calculated with the computer software. Using a SUVmax of ≥2.0 as a reference indicated malignancy. Take pathological diagnosis result as golden standard. The detection rate and accuracy rate of mammography, ultrasonography, MRI and 18F-FDG PET-CT identifing primary breast carcinoma were calculated, χ2 test was used for testing the difference of each examination.Results: Of the 73 patients, primary breast carcinoma was proven in 60 women, including invasive carcinoma of no special type(NST) in 41(68.3%), ductal carcinoma in situ(DCIS) in 9(15.0%), invasive micropapillary carcinoma in 3(5.0%),invasive lobular invasive(ILC) in 2(3.4%), DCIS with early invasion in 2(3.3%), microinvasive carcinoma in 2(3.3%) and glycogen-rich clear cell carcinoma in one(1.7%). No tumor was found at mastectomy in the other 13 women. A total of 61 women underwent mammography examination. Tumors of 51 patients were found in the specimens. The primary breast carcinomas were detected by mammography in 16 patients and no suspicious lesions were detected in 35 patients. No tumor was found at mastectomy in the other 10 women with no suspicious findings on mammography. The detection rate and accuracy rate of mammography in the diagnosis of the primary malignancy were 31.4%(16/51) and 42.6%(26/61).There are scattered areas of fibroglandular density in 9(56.3%). The breasts are heterogeneoously dense in 7(43.7%). The Finding of carcinoma was focal asymmetry in 8(50.0%), calcifications in 5(31.3%), mass in one(6.3%), mass with calcifications in one(6.2%) and focal asymmetry with calcifications in one(6.2%). The morphology of calcifications was fine pleomorphic in 3 patients and amorphous in 2 patients. The distribution of calcifications was regional in 2 patients, segmental in 2 patients and grouped in one patients. No suspicious findings were detected on mammography in 35 patients. Of 35 patiens, the primary breast carcinomas were detected by MRI in 33 patients, including 21(63.6%) non-mass lesions and 12(36.4%) masses. A total of 69 women underwent ultrasonography examination. Tumors of 56 patients were found in the specimens. The primary breast carcinomas were detected by ultrasonography in 15 patients and no suspicious lesions were detected in 41 patients. No tumor was found at mastectomy in the other 13 women with no suspicious findings on ultrasonography. The detection rate and accuracy rate of mammography in the diagnosis of the primary malignancy were 26.8%(15/56) and 40.6%(28/69). Ultrasonography detected 15 primary malignancy, including hyperechoic mass in 10(66.7%), multiple hyperechoic areas arraying in a duct or a duct that branches in 2(13.3%), hyperechoic area arraying in a duct in 2(13.3%) and extension of duct with calcifications in one(6.7%). Size of the masses ranged from 0.5 cm to 1.7 cm, mean(1.1±0.3) cm. The morphology was irregular in 8 patients, round or oval in 2 patients, the margin of lesions was not circunscribed in 9 patients and circunscribed in one patients. 6 cases had absent vascularity, 3 cases had internal vascularity and one case had vessels in rim. The posteroir features was no posteroir features in 5 cases, enhancement in 4 cases and shadowing in 1 cases. One cases had calcifications in a mass. No suspicious findings were detected on ultrasonography in 41 patients. Of 41 patiens, the primary breast carcinomas were detected by MRI in 39 patients, including 23(63.9%) non-mass lesions and 16(41.0%) masses. 19 patients underwent MRI-directed Sonography examination, including hyperechoic mass in 10(52.6%), focal hyperechoic area in 5(26.3%) which was focal enhancement in 3 patients, linear enhancement in 2 patients, multiple hyperechoic areas arraying in a duct or a duct that branches in 3(15.8%) which was segmental enhancement in 2 patients and linear enhancement in one patients on MRI and extension of duct within hyperechoic area in 0ne(5.3%). Size of the masses ranged from 0.6 cm to 2.0 cm, mean(1.1±0.4)cm. The morphology were irregular, the margin of lesions were not circunscribed. 5 cases had absent vascularity, 3 cases had internal vascularity and 2 cases had vessels in rim, the posteroir features was no posteroir features in 7 cases, shadowing in 2 cases and enhancement in one cases, 2 cases had calcifications in a mass. Among 60 women, the primary breast carcinomas were detected by MRI in 58 patients and no suspicious enhancement lesions were detected in 2 patients. No tumor was found at mastectomy in the other 13 women with no suspicious enhancement in 9 patients and suspicious enhancement in 4 patients on MRI. The detection rate and accuracy rate of MRI in the diagnosis of the primary malignancy were 96.7%(58/60) and 91.8%(67/73). Of 58 patients, Amount of fibroglandular tissue(FGT) is assessed on fat-saturated T1 W imaging or non-fat-saturated T1 W imaging in 58 women, including heterogeneous fibroglandular tissue in 36(62.1%), scattered fibroglandular tissue in 16(27.6%), extreme fibroglandular tissue in 4(6.9%) and almost entirely fat in 2(3.4%). The level of background parenchymal enhancement(BPE) is assessed on the first postcontrast image at approximately 90 seconds, including minimal in 46(79.3%), mild in 11(19.0%) and moderate in one(1.7%). MRI detected 58 primary malignancy, including 38(65.5%) non-mass lesions and 20(34.5%) masses. Size of the masses ranged from 0.7 cm to 1.7 cm, mean(1.1±0.3)cm; The morphology was irregular in 12(60%) and oval or round in 8(40%), the margin of all lesions were irregular; The internal enhancement pattern was heterogeneous in 13(65%), homogeneous in 4(20%) and rim enhancement in 3(15%). The time intensity curve was Type Ⅲ(washout) in 13(65%), Type Ⅱ(plateau) in 6(30%) and Type Ⅰ(persistent) in 1(5%). The distribution of non-mass lesions was linear in 14(36.8%), segmental in 13(34.2%), focal in 9(23.7%) and multiple regions in 2(5.3%); The internal enhancement pattern was heterogeneous in 25(65.8%), homogeneous in 8(21.1%), clumped in 4(10.5%) and clumped ring in 1(2.6%). The time intensity curve was Type Ⅲ(washout) in 16(42.1%), Type Ⅰ(persistent) in 15(39.5%) and Type Ⅱ(plateau) in 7(18.4%). A total of 22 women underwent 18F-FDG PET-CT examination. Tumors of 19 patients were found in the specimens. The primary breast carcinomas were detected by 18F-FDG PET-CT in 5 patients and no suspicious lesions were detected in 14 patients. No tumor was found at mastectomy in the other 3 women with no suspicious findings on 18F-FDG PET-CT. The detection rate and accuracy rate of 18F-FDG PET-CT in the diagnosis of the primary malignancy were 26.3%(5/19) and 36.4%(8/22). All of carcinomas was mass. Size of the masses ranged from 1.0 cm to 1.7 cm, mean(1.3±0.3) cm. No suspicious findings were detected on 18F-FDG PET-CT in 14 patients. Of 14 patiens, the primary breast carcinomas were detected by MRI in 13 patients, including 8(61.5%) non-mass lesions and 5(38.5%) masses. Size of the masses ranged from 0.8 cm to 1.2 cm, size of 3 masses was smaller than 1.0 cm. The detection rate and accuracy rate were 31.4%, 42.6%; 26.8%, 40.6%; 96.7%, 91.8%; versus 26.3%, 36.4%, respectively, in the diagnostic evaluation of identifing primary breast carcinoma on mammography, ultrasonography, MRI and 18F-FDG PET-CT. Results of χ2 test revealed that MRI showed higher detection rate and accuracy rate of primary malignancy than mammography, ultrasonography and 18F-FDG PET-CT(P < 0.001). The detection rate and accuracy rate of MRI, mammography, ultrasonography and 18F-FDG PET-CT in identifing primary breast carcinoma had no significant difference.Conclusion: MRI showed higher detection rate and accuracy rate of primary malignancy than mammography, ultrasonography and 18F-FDG PET-CT. The detection rate and accuracy rate of MRI, mammography, ultrasonography and 18F-FDG PET-CT in identifing primary breast carcinoma had no significant difference. Breast MRI should be taken in search of occult breast malignancy in women with axillary lymph node metastases.Focal asymmetry or calcifications were common mammography features. Small size of hyperechoic mass, multiple hyperechoic areas arraying in a duct or a duct that branches and focalhyperechoic area with or without calcification and extension of duct were ultrasonography features. Small size of mass and focal, ductal or segmental enhancement of non-mass lesion were common MRI features of occult malignancy. Mass(diameter >1.0cm) was 18F-FDG PET-CT 18F-FDG PET-CT.