Introduction 1 11 8 12 22 15 23 25 19 26 27 4 12 16 17 28 31 4 9 13 17 18 23 24 29 18 25 32 Materials and methods Patients and US A total of 138 patients (age: 25–79 years, median 54 years) were investigated in a multicentre trial with complementary mammary diagnostic procedures over a 36-month period (November 2002 to November 2005). All women gave informed written consent for their results to be used for programme research and evaluation. On the basis of US findings, each lesion was evaluated based on size, shape (ellipsoid, round, irregular), margins (smooth, macrolobulated, microlobulated, speculated, angulated, ill-defined), posterior sonographic artefacts (shadowing, through transmission, no posterior artefacts), echogenicity (hyperechogenic, isoechoic, hypoechoic), presence of calcifications and ductal extension. Investigations were supplemented by clinical examination and mammography in two planes. Ultrasound lesions were examined in three planes using PD and digital imaging with the GE Logiq 9 (GE Medical Systems, Milwaukee, WI, USA) US units. All investigations were carried out with a high-resolution multifrequency linear matrix array transducer (Linear Array M10L, 5–10 MHz) with the modalities of THI, spatial compounding (crossbeam), speckle reduction imaging (SRI) and contrast-medium-enhanced PD with CHI and additional three-dimensional (3D) imaging. Imaging documentation of digital raw data in single-image and short sequences was effected using a Picture and Communication System (PACS). Study population The patient population was divided into two groups. In group 1, we focused on the advantage of THI, SC and an adaptive algorithm for SRI. In group 2, we focused on CHI with PD. Group 1 Thirty-eight patients (37–62 years) with 14 benign and 24 malignant tumours were examined in fundamental mode and with harmonic imaging with a high-frequency matrix-array transducer with the modalities of THI, SC and an adaptive algorithm for SRI. Prospectively, fundamental and tissue harmonic mode were used alone and in combination with all available levels of SC (cross beam: low, medium, high, maximum) and five levels of SRI. In patients without tumour lesions, criteria were differentiation of normal fibroglandular tissue from premammary and retromammary fat, including the Cooper’s ligaments and ducts. Criteria that were evaluated for differential diagnosis in patients with lesions were margin, infiltration of malignant tumours, echo pattern with tissue components, calcifications, posterior lesion boundary and posterior acoustic features. After optimising system settings, a three-level score was applied to enable comparison of the quality of scans with fundamental imaging (0=equal, −1=inferior, +1=superior). Group 2 One hundred patients (25–76 years, median 53 years) comprised 29 probably benign [Breast Imaging Reporting and Data System (BI-RADS III)] and 71 malignant (BI-RADS IV–V) tumours confirmed by vacuum-assisted biopsy in 100/100 lesions and 78/100 cases additionally in the course of surgery. Tumour diameters varied between 4 and 15 mm (mean: 9 mm). Histological confirmation was obtained in all cases. All patients were comparatively investigated with fundamental B scan, THI and CHI with PD. After the B scan and evaluation of vascularisation in native PD, we used an echo signal amplifier of the second generation with low mechanical index (MI) technology. A bolus injection of Optison was administered (0.5 ml Optison diluted with 20 ml with NaCl solution and subsequent injection of another 20 ml NaCl). The bolus of CM was injected intravenously, and spreading of the contrast enhancement and washout in the tumours were followed for at least 20 min. A low MI (0.15–0.25) was chosen to avoid early destruction of the microbubbles. CM enhancement was appraised for up to 20 min. Moreover, additional 3D evaluations of the cine sequences were also possible retrospectively in consequence of the archiving of dynamic digital images of up to 180 single images and 10- loop. The images archived in B scan and THI could also be processed retrospectively, with various phases of SRI, which enabled marginal contours of the tumours to be highlighted by homogenising tissue structures. The patients were given detailed information before each injection of CM, particularly with respect to a possible predisposition to allergic reactions. Written consent was obtained. Studies were performed only in patients with normal renal function. Approval had been obtained from the hospital’s ethics committee. Histopathological correlation Histopathological correlation was determined based on surgical and biopsy findings. Tumour size, grade, histological subtype and presence of invasion were documented. Pathological imaging correlation was performed in conjunction with both pathologist and breast imagers with regard to lesion location and size to ensure that the imaged lesions were evaluated histologically. Breast biopsy US-guided biopsies were performed as vacuum-assisted biopsies, mostly with an 11-gauge needle. Up to 12 representative tissue samples were taken. When there were malignant findings, US-guided wire marking was mostly undertaken before surgical excision. Afterwards, follow-up examinations were carried out at 6-month intervals. Statistical analysis Elementary statistics were computed. Fisher’s two-tailed exact test was applied for statistical assessment of powers for discriminating different vascularisation and comparison of benign tumours versus carcinomas after the use of Optison. Results Group1 THI has no effect on image quality in the near field. THI needs at least 1 cm of tissue penetration. The effect is best seen in the middle and far field, especially around the focus zone. Cutis and the first 10 mm of fat and Cooper’s ligaments are already seen in fundamental mode, with better visibility and delineation with SC (cross beam: level medium) and SRI. The reflex of the anterior mammary fascia appears thinner and brighter with SC (cross beam: level medium to high) than in fundamental imaging. Ducts in deeper areas are best visualised with a combination of SC and THI. The main disadvantage is a significant reduction of the frame rate caused by SC, especially when THI is possible in addition. The first impression from image analysis of all combinations of SC and SRI was that higher levels of SC could be avoided by using, in addition, an SRI level of 1 or 2, giving the same advantage over the fundamental image with less reduction of frame rate. The best compromise for screening examinations of breast tissue is the combination of SC (level low) and SRI (level 1 or 2) with THI in small breasts. Fat appears slightly more echogenic, which potentially helps to define small tumours. The main limitation of THI was the reduced penetration (16% of our patients). In patients with large breasts and abundant fibrous tissue, fundamental imaging should be preferred. Lesion detection and differentiation 1 33 Fig. 1  left side  right side a b  2 1 Fig. 2 a b a b  Table 1 Results of comparison of fundamental versus combination of tissue harmonic imaging (THI), spatial compounding (SC) (cross beam: level low) and speckle reduction imaging (SRI) level 1 Criteria −1 0 +1 Margin 1 11 12 Infiltration (existent in 19/24 malignant cases) 1 3 15 Echo pattern/tissue components 3 10 11 Calcifications 1 2 3 Posterior lesion boundary 1 7 16 Posterior acoustic features 9 9 6 Score : −1=fundamental superior, 0=no difference, +1=combination superior Group 2 Seventy-one cases confirmed by biopsy were classified as malignant (BI-RADS IV–V), and 29 cases were categorised as most likely benign (BI-RADS III). Histological confirmation by vacuum biopsy was also performed at patients’ expressed request and in cases of malignancy or borderline lesions also by surgery (82/100). Histological appraisal Benign lesions Histological finding detected four cases with a scar or intraductal inflammatory origin or ductal lesions, two cases of papillomas, five cases of fibrocystic mastopathy and 18 cases of fibroadenomas. Malignant lesions 3 4 5 2 Fig. 3 a d a b c d  Fig. 4 a d 3 a b c d  Fig. 5 a b a b c f a b c d e f  Table 2 Comparison of benign tumours versus carcinomas. Vascularisation after administration of CM [0.5 ml Optison]   n n Power Doppler Power Doppler +CM Power Doppler Power Doppler + CM Early phase (1–5 min)     Marginal vessels 11/29 (38%) 24/29 (83%) 43/71 (60%) 67/71 (94%) Penetrating vessels 4/29 (14%) 12/29 (41%) 28/71 (39%) p Central vessels 0/29 (0%) 6/29 (20%) 21/71 (29%) p Late phase (5–20 min)     Diffuse enhancement 0/29 0/29 0/71 p  p The results of our own investigations indicate that the tumours can be identified better during biopsy in echo-inhomogeneous tissue using CHI in biopsies of smaller tumours under 10 mm in size. This enables false negative findings to be avoided in the histopathological investigations. After injection of CM, satellite foci and lymph nodes may also show increased vascularisation, which is manifested especially in harmonic imaging with PD. Discussion 34 5 7 35 8 35 41 4 7 9 12 35 8 36 37 38 39 21  p 19 27 40 15 5 7 20 21 35 2 7 22 35 Tumour lesions of BI-RADS IV and V have to be clarified by biopsy, in particular, punch biopsy or vacuum biopsy. Consequently, US-guided biopsy is appropriate when it allows unequivocal lesion identification. US-guided interventions are required for further clarification in mammography occult findings and preoperative wire marking. In our own investigations, harmonic imaging was employed for definitive preoperative wire marking, to carry out a US-guided vacuum biopsy and also with CM enhancement for improved tumour detection. 42 43 12 13 17 22 24 25 29 31 12 4 12 16 18 24 29 31 44 4 12 25 29 44 45 4 18 31 14 15 20 32 Conclusion In conclusion, we feel confident that US using THI and CHI technologies is a valuable tool for evaluating focal breast lesions, in particular in mammography-dense breasts. If utilised extensively, it will be a cost-effective tool to facilitate detection and differentiation of malignant breast lesions in early, well-treatable stages and will thus help in reducing breast cancer mortality.