Imaging features of primary and secondary malignant tumours of the sacrum.

Malignant tumours of the sacrum may be primary or secondary. While sacral metastases are frequently encountered, a diagnostic dilemma can present when there is a single sacral bone tumour with no history or evidence of malignancy elsewhere in the body. Familiarity with the imaging features and clinical presentations of primary malignant bone tumours is helpful in narrowing the differential. This pictorial review will illustrate with both common and uncommon malignant sacral tumours CT, MRI and positron emission tomography/CT, highlighting the specific features of each.

Mammographic appearance of ductal carcinoma in situ does not reliably predict histologic subtype.

Histologic subtypes of ductal carcinoma in situ (DCIS) have been correlated with disease prognosis. There are conflicting reports on whether the grade of DCIS can be predicted by the morphology of calcifications seen on mammography. We undertook this study to determine whether the grade of DCIS can be reliably and accurately determined by mammography prior to excisional biopsy. Ninety consecutive cases of DCIS from 1993 to 1996 were identified, of which 75 cases had mammograms available for review. Any lesion with invasion was excluded. The mammogram showed only a mass in 10 of 75 cases, a mass and calcifications in 3 of 75 cases, and calcifications alone in 62 of 75 cases. Three board-certified radiologists with special expertise in mammography reviewed and categorized the mammographic findings as well, intermediate or poorly differentiated DCIS without knowledge of the histologic diagnosis. Histologic grading was performed without knowledge of the mammographic finding. Receiver operating curves (ROCs) were computed for each of the radiologists. For microcalcifications, the ROC comparisons of the radiologists' opinions of tumor grade and random chance were not significantly different. In those cases with available magnification views, the grade assessment did not change significantly. If only a mass was present on mammography, well-differentiated DCIS was the predominant histologic subtype. A histologic grade of DCIS cannot accurately be determined prospectively based on the mammographic appearance of microcalcifications. However, if only a mass is present, this is more likely to represent well-differentiated DCIS.

Previous breast biopsy for benign disease rarely complicates or alters interpretation on screening mammography.

OBJECTIVE: It has been suggested that breast screening leads to too many biopsies for benign disease that permanently scar the breast and confuse the interpretation of subsequent mammograms. We undertook retrospective and prospective studies to determine how often an excisional biopsy for benign breast disease complicates or alters interpretation of screening mammograms. MATERIALS AND METHODS: Retrospective review of our screening center database yielded 31,025 asymptomatic patients who had routine mammographic screening studies between 1993 and 1996. Of the 58,538 examinations of these patients, 53,510 were of patients who had no history of breast biopsy and 5028 were of patients who had a history of breast biopsy for benign disease. Recall rates were compared between the two groups. In the prospective study, radiologists reviewed the mammograms of 1997 consecutive patients presenting to the screening center, 173 of whom reported a prior breast biopsy for benign disease. The radiologist interpreting the images determined how often evidence of the biopsy site was apparent on the mammogram and how often such changes necessitated additional imaging. RESULTS: In the retrospective study, 3296 (6%) of the 53,510 studies done in patients who did not have a biopsy for benign disease and 360 (7%) of the 5028 studies done in women who had a biopsy for benign disease led to additional imaging. Eight recalls for further imaging (0.16%) among the 5028 studies in women with a prior biopsy for benign disease were related to the biopsy site. In the prospective study, 24 (14%) of the 173 women who had a biopsy for benign disease had mammographic evidence of the biopsy site. Nine (5%) of the 173 women who had previously had a biopsy for benign disease and 86 (5%) of the 1824 patients without a prior biopsy were recalled for additional imaging. No women were recalled because a previous breast biopsy for benign disease led to confusion or diagnostic concern. CONCLUSION: Changes in patients' breasts due to previous excisional biopsies for benign breast disease rarely pose a diagnostic dilemma in the interpretation of routine screening mammograms.

Digital tomosynthesis in breast imaging.

PURPOSE: To describe and evaluate a method of tomosynthesis breast imaging with a full-field digital mammographic system. MATERIALS AND METHODS: In this tomosynthesis method, low-radiation-dose images were acquired as the x-ray source was moved in an arc above the stationary breast and digital detector. A step-and-expose method of imaging was used. Breast tomosynthesis and conventional images of two imaging phantoms and four mastectomy specimens were obtained. Three experienced readers scored the relative lesion visibility, lesion margin visibility, and confidence in the classification of six lesions. RESULTS: Tomosynthesis image-reconstruction algorithms allow tomographic imaging of the entire breast from a single arc of the x-ray source and at a radiation dose comparable with that in single-view mammography. Except for images of a large mass in a fatty breast, the tomosynthesis images were superior to the conventional images. CONCLUSION: Digital mammographic systems make breast tomosynthesis possible. Tomosynthesis may improve the specificity of mammography with improved lesion margin visibility and may improve early breast cancer detection, especially in women with radiographically dense breasts.