Comparison of written reports of mammography, sonography and magnetic resonance mammography for preoperative evaluation of breast lesions, with special emphasis on magnetic resonance mammography

Abstract

was diagnosed by mammography in 78.9% and by MR mammography in 68.4% of patients. Combination of all three diagnostic methods lead to the best results for detection of invasive cancer and multifocal disease. However, sensitivity of mammography and sonography combined was identical to that of MR mammography (ie 94.6%).

Introduction

].

]. In those studies, MR mammography was performed and evaluated by highly specialized radiologists in a research setting. It was therefore the purpose of the present prospective study to compare the validity of MR mammography with mammography and sonography in clinical routine practice. Findings for the three diagnostic methods documented on routine reports that were available to the surgeon preoperatively formed the basis of this comparison. Special emphasis was placed on the identification of multifocal and multicentric invasive disease.

Patients

Between September 1995 and September 1998, 413 patients with abnormal breast findings were referred for histological evaluation to the Department of Gynecology of the Friedrich-Schiller University, Jena, Germany. Patients had been selected and referred because of the presence of breast lesions detected by palpation and/or mammography and/or sonography. In addition, MR mammography was performed in all patients. We excluded five patients with invasive cancer who had a history of core-needle or fine-needle biopsy cancer within 2 weeks before referral, because the presence of haematoma may mimic false-positive findings on MR mammography. In addition, five patients who did not keep still during MR mammography were excluded.

Imaging

were excluded from analysis because the value of sonography for detection of premalignant disease is limited. Mammography was not performed in 32 patients who were younger than 30 years or who had had a mastectomy with suspected local recurrence. For all patients, written reports of mammographic, sonographic and dynamic MR mammographic findings were available preoperatively.

The majority of mammograms (68%) were performed at the Institute for Diagnostic and Interventional Radiology, Friedrich-Schiller-University, using a senograph DMR (GE Medical Systems, Milwaukee, Wisconsin, USA) with standard craniocaudal and mediolateral oblique projections. Mammograms obtained at other institutions that were considered to match the quality standards of our institution were also accepted for evaluation.

All sonography and MR examinations were carried out at the Department of Gynecology and the Institute for Diagnostic Interventional Radiology, Friedrich-Schiller-University, respectively. Sonography was done using a 7.5-MHz linear array probe with a Sonoline Versa Pro (Siemens, Erlangen, Germany). MR mammography was performed exclusively at the Institute for Diagnostic Interventional Radiology, using a Gyroscan ACSII (Philips, Nijmegen, The Netherlands) with a field strength of 1.5 T using a double-breast coil. Dynamic T1-weighted images were aquired using a multislice two-dimensional fast-field-echo (FFE) sequence. We used the following parameters: TR 97, TE 5.0, flip angle 80°, slice thickness 4.0 mm, gap 0.4 mm, field of view 350 mm and transverse orientation. In addition T2-weighted images (4000/300/90°/4.0 mm/0.4/350 mm) were obtained. As contrast medium, 0.1 mmol gadolinium-DTPA/kg body weight (Magnevist; Schering, Berlin, Germany) was used and injected as a bolus. One unenhanced and seven enhanced studies were acquired with an acquisition time of 1 min. Criteria for malignancy were signal enhancement of 90% or more within the first 2 min after bolus injection and signal plateau or washout phenomena afterward. Additional criteria were irregular borders of the lesion and low signal intensity in the T2-weighted images.

Mammograms were read by three different radiologists, sonography was done by three different gynaecologists and MR mammography was interpreted by a total of six different radiologists.

Definition for multifocal carcinoma was a distance of less than 3 cm and for multicentric carcinoma a distance over 3 cm between various lesions.

Statistical analysis

Interpretation of the various diagnostic procedures was compared with the histological examination with regard to sensitivity, specificity, accuracy, and positive and negative predictive value. Criteria for suspected malignancy in the written reports were the terms 'cancer', 'malignant lesion or tumor', or 'suspicious for cancer'. Sensitivity, specificity, negative and positive predicitive value, and accuracy were evaluated as follows:

Sensitivity = patients with suspected breast cancer/patients with histologically confirmed breast cancer

Specificity = patients with suspected benign disease/patients with histologically confirmed benign disease

Positive predictive value = patients with histologically confirmed breast cancer/patients with suspected breast cancer

Negative predictive value = patients with histologically confirmed benign disease/patients with suspected benign disease

Accuracy = patients with true-positive and true-negative detected disease/patients with histologically confirmed breast cancer

test.

Results

. The mean age of patients was 58 years (range 19-85 years).

).

). Of 10 invasive cancers missed by MR mammography, eight were found by mammography and sonography. By all three techniques, one invasive ductal carcinoma (pT1b) was misinterpreted as fibroadenoma. In another patient, a microinvasive lobular carcinoma of 5 mm diameter was not detected with mammography and MR mammography, whereas sonography detected a solid, benign tumour. MR mammography identified 10 invasive cancers (5.2%) that were missed by mammography and sonography, whereas one invasive cancer was found by mammography alone. By sonography alone, not a single case of invasive disease was detected when MR mammography or mammography were nonsuspected.

< 0.05 versus mammography + sonography). Multifocal invasive disease was suspected in 12 patients by mammography, in 13 patients by sonography, and in 16 patients by MR mammography, but only unifocal disease was confirmed by histology. Out of nine patients with histologically confirmed multicentric invasive cancer, eight (88.8%) of these cancers were detected by MR mammography and five (55.5%) by mammography or sonography. One patient was diagnosed with multicentric invasive-lobular carcinoma stage pT2G2, which had been misinterpreted as benign tumour by sonography and mammography, and as haematoma by MR mammography.

increased to 87% (not significant).

Discussion

].

). The present results are similar with regard to sensitivity and specificity for the detection of malignant breast lesions, with MR mammography reaching the highest sensitivity of all imaging procedures.

]. In the present study, we also found the highest sensitivity, specificity, and positive and negative predictive values for the combination of all three methods. Combination of mammography and sonography was as sensitive as MR mammography alone (94.6% versus 94.6%).

].

] found that lobular and mucinous carcinomas had a low microvessel density.

]. We found a detection rate of multifocality of 66.7% by MR mammography, as compared with 26.2% by mammography and sonography. However, in 16 patients multifocal invasive disease as diagnosed by MR mammography was shown to be unifocal by histology.

] reported that MR mammography yielded the highest sensitivity for detection of multicentricity as compared with mammography and sonography (89, 66 and 79%, respectively) in 38 patients. These findings are comparable with the present results, in which eight out of nine multicentric cancers were diagnosed correctly.

] demonstrated two cases without early contrast enhancement.

The present study showed that, for detection of breast cancer, MR mammography is not superior to a combination of sonography and mammography. For identification of multifocal or multicentric disease, MR mammography proved to be the most accurate technique.

Figures and Tables

Histopathology of 185 invasive cancers

= 254)

< 0.05, versus sonography. NPV, negative predictive value; PPV, positive predictive value.

= 254)

< 0.05, versus MR mammography and mammography. NPV, negative predictive value; PPV, positive predictive value.

= 10) for 185 invasive cancers

Review of the literature: case series that compared mammography, sonography and MR mammography in patients with benign tumours and invasive cancer

-, not indicated; Sens, sensitivity; Spec, specificity.

Keywords

• breast lesions
• diagnostic methods