Progress in early breast cancer detection

Breast Microcalcifications Studied with 3d Contrast-enhanced High-field Magnetic Resonance Imaging: More Accuracy in the Diagnosis of Breast Cancer

Aims

To evaluate the reliability of magnetic resonance imaging (MRI) performed with three-dimensional (3D) sequences in mammographically detected breast microcalcifications.

Methods

During an 8-month period, a group of 28 patients with mammographically detected microcalcifications suspicious for malignancy underwent MRI. Their ages ranged from 33 to 65 years. Examinations were performed with a 1.5 Tesla MR unit and a 3D T1 weighted sequence. Images were interpreted on the basis of morphologic parameters and dynamic behavior in the uptake of contrast medium (Gd-DTPA). Histologic findings were considered as the gold reference.

Results

Histologic analysis revealed invasive carcinoma in 7 patients, 3 of which were associated with foci of lobular carcinoma in situ. Intraductal carcinoma was diagnosed in 8 patients, 1 of which was associated with a tubular carcinoma. Benign lesions accounted for 13 patients. All the neoplastic conditions showed enhancement on MR images (sensitivity, 100%), whereas early and intense enhancement was noted in 5 of 13 benign lesions (specificity, 61%). The positive predictive value was 75% and negative predictive value, 100%.

Conclusions

Although an overlap in the enhancement behavior of malignant and some benign lesions is clearly evident, a careful interpretation of MR images is helpful in detecting and mainly ruling out breast cancer combined with mammographically suspicious microcalcifications.

Improving PET imaging for breast cancer using virtual pinhole PET half-ring insert

A PET insert with detector having smaller crystals and placed near a region of interest in a conventional PET scanner can improve image resolution locally due to the virtual-pinhole PET (VP-PET) effect. This improvement is from the higher spatial sampling of the imaging area near the detector. We have built a prototype half-ring PET insert for head-and-neck cancer imaging applications. In this paper, we extend the use of the insert to breast imaging and show that such a system provides high resolution images of breast and axillary lymph nodes while maintaining the full imaging field of view capability of a clinical PET scanner. We characterize the resolution and contrast recovery for tumors across the imaging field of view. First, we model the system using Monte Carlo methods to determine its theoretical limit of improvement. Simulations were conducted with hot spherical tumors embedded in background activity at tumor-to-background contrast ranging from 3:1 to 12:1. Tumors are arranged in a Derenzo-like pattern with their diameters ranging from 2 to 12 mm. Experimental studies were performed using a chest phantom with cylindrical breast attachment. Tumors of different sizes arranged in a Derenzo-like pattern with tumor-to-background ratio of 6:1 are inserted into the breast phantom. Imaging capability of mediastinum and axillary lymph nodes is explored. Both Monte Carlo simulations and experiment show clear improvement in image resolution and contrast recovery with VP-PET half-ring insert. The degree of improvement in resolution and contrast recovery depends on location of the tumor. The full field of view imaging capability is shown to be maintained. Minor artifacts are introduced in certain regions.

Positron emission mammographic instrument: initial results

Performance characteristics of a positron emission mammographic (PEM) instrument were studied. This dedicated metabolic breast imaging system has spatial resolution of 2.8-mm full width at half maximum (FWHM), coincidence resolving time of 12-nsec FWHM, and absolute efficiency of 3%. Hot spots with diameter of 16 mm in a phantom with signal-to-background activity ratio of 6:1 were distinguishable with a scanning time of 5 minutes.

Effect of routine mammography practice on tumour size of a registry-based series of breast cancer cases compared with those observed in a screening cohort

Routine mammography (MX) practice based on self-referral is considered not to be susceptible to monitoring at the population level. Invasive breast cancer cases notified to the Romagna Cancer Registry between 1989 and 1991 (total 654) were stratified by MX experience and were compared for the proportion of lesions greater than 2 cm in size (T2+) with cases observed in the study group of the Swedish Two Counties Screening Trial (TCST). Any MX more than 6 months prior to diagnosis was considered a previous routine examination. The proportion of cases registered in Romagna within 6-11 months of the most recent MX was quite similar to that shown by the interval cases of the TCST (50% vs 53%). T2+ cases registered in Romagna 12-23 months (27%) and 24-35 months (19%) after previous MX were similar in frequency to those detected at second and later screens in the TCST (22%). For longer intervals, the percentage of large tumours in the Romagna series increased, up to 45% among the cases registered more than 48 months since last MX (p < 0.0001). The whole group of cases with previous MX in Romagna and its counterpart in the TCST (i.e. interval cases + cases detected at second and later screens) had the same size distribution (35% vs 34%). The frequency of large tumours in the total series from Romagna was greater than in the total study group of the TCST (45% vs 36%, p < 0.0001). The difference was entirely accounted for by the cases with no previous MX.

c-erbB-2 oncoprotein in screen-detected breast carcinoma: an immunohistological study

This study was aimed at comparing screen-detected and symptomatic breast carcinomas with regard to the prevalence of positive immunostaining for c-erb-B-2 oncoprotein. Paraffin sections of 81 breast carcinomas detected through the National Screening Programme were examined for the over-expression of c-erbB-2 oncoprotein using the avidin-biotin immunoperoxidase technique and 2 different specific antibodies: 21N and 4D5. Twenty-one other carcinomas detected in symptomatic patients were similarly examined for comparison. The screen-detected lesions were of 2 types: palpable and impalpable which required needle localization prior to surgical removal. Of the 81 screen-detected tumours, only 8 were c-erbB-2 positive, compared with 5 out of 21 non-screen-detected tumours. When only invasive carcinomas were considered, 5 out of 63 screen-detected cases were positive, compared with 5 out of 15 symptomatic cases. Four out of the 5 screen-detected positive invasive carcinomas were clinically palpable. Our results show an obvious trend towards a lower prevalence of c-erbB-2 oncoprotein over-expression in screen-detected carcinomas. As this over-expression is thought to be associated with increased tumour aggressiveness, the findings suggest a low prevalence of aggressive tumours in screen-detected lesions, particularly impalpable invasive carcinomas, identified so far.

Nonpalpable invasive breast cancer

The use of mammography has resulted in 1464 breast biopsies for nonpalpable abnormalities at the University of Virginia in the 10 years 1980 to 1989. Two hundred sixty-four cancerous lesions (18%) were found. One hundred seventy-eight of these (67%) were in situ lesions. Invasive cancer (86 of 264 lesions or 33%) forms the basis for this report. Mammographic findings leading to biopsy were a mass in 61 of 86 cases (71%), microcalcifications in 23 of 86 (27%), or both in 2 of 86 cases. Histologic subtypes were infiltrating ductal (63 of 86), infiltrating lobular (14 of 86), and other infiltrating (9 of 86). Mastectomy was performed in 71 of 86 lesions (82%), lumpectomy/radiation in 14 of 86 (16%), and lumpectomy alone in 1 of 86 lesions. Division of the tumors into size with nodal status revealed 19 of 86 lesions (22%) less than 0.5 cm with 0 of 14 positive nodes. Thirty-nine of eighty-six lesions (46%) measured 0.6 to 1.0 cm with 10 (26%) positive nodes. Twenty-eight of eighty-six lesions (32%) measured more than 1.0 cm with 8 of 28 (28%) positive nodes. Nodal status is unknown for eight patients. Overall 18 of 78 lesions (23%) had positive nodes. Median follow-up is 44 months. Disease-free survival rate is 92% (79 of 86 patients) and overall survival rate is 94% (81 of 86 patients). Six of seven recurrences occurred in node-positive patients. For those with negative or unknown nodes, the disease-free survival rate is 98% (67 of 68 patients). These findings emphasize the benefit of early detection of breast cancer through the use of mammography.