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Biomedical subjects

G Newstead

Publications and source records attributed to G Newstead.

12 recordsLinked to original sources
PubMed2001

International investigation of breast MRI: results of a multicentre study (11 sites) concerning diagnostic parameters for contrast-enhanced MRI based on 519 histopathologically correlated lesions.

A multicentre study was undertaken to provide fundamentals for improved standardization and optimized interpretation guidelines of dynamic contrast-enhanced MRI. Only patients scheduled for biopsy of a clinical or imaging abnormality were included. They underwent standardized dynamic MRI on Siemens 1.0 (163 valid lesions > or = 5 mm) or 1.5 T (395 valid lesions > or = 5 mm) using 3D fast low-angle shot (FLASH; 87 s) before and five times after standardized bolus of 0.2 mmol Gd-DTPA/kg. One-Tesla and 1.5 T data were analysed separately using a discriminant analysis. Only histologically correlated lesions entered the statistical evaluation. Histopathology and imaging were correlated in retrospect and in open. The best results were achieved by combining up to five wash-in or wash-out parameters. Different weighting of false-negative vs false-positive calls allowed formulation of a statistically based interpretation scheme yielding optimized rules for the highest possible sensitivity (specificity 30%), for moderate (50%) or high (64-71%) specificity. The sensitivities obtained at the above specificity levels were better at 1.0 T (98, 97, or 96%) than at 1.5 T (96, 93, 86%). Using a widely available standardized MR technique definition of statistically founded interpretation rules is possible. Choice of an optimum interpretation rule may vary with the clinical question. Prospective testing remains necessary. Differences of 1.0 and 1.5 T are not statistically significant but may be due to pulse sequences.

Adult↗
PubMed1997

Fatty and fibroglandular tissue volumes in the breasts of women 20-83 years old: comparison of X-ray mammography and computer-assisted MR imaging.

OBJECTIVE: A method for segmenting MR images of the breast was applied to determine fatty and fibroglandular tissue volumes in breasts of women in different age groups. The results were compared with subjective assessments of breast density from X-ray mammograms in the same patients. MATERIALS AND METHODS: Two experienced mammographers assessed the percentage of fat in the breasts of 40 women who were 20-83 years old. MR images were obtained on a 1.0-T scanner equipped with a bilateral receive-only breast coil. Images were acquired using a three-dimensional T1-weighted gradient-echo sequence with a 1.25 x 1.4 x 2.5 mm resolution. On average, breast parenchyma appeared in 30 images in each breast. Image segmentation was based on a semiautomated, two-compartmental (fatty and fibroglandular tissue) model that accounts for partial volume effects. To validate the accuracy of the MR imaging segmentation technique, we performed a phantom study using an identical imaging sequence. RESULTS: The accuracy of the MR imaging segmentation of the phantom was of the order of 2%. In our subjects, fat content was 42.5% +/- 30.3% (mean +/- SD) on mammography versus 66.5% +/- 18% on MR images. Although we found a significant correlation (r = .63) between the two techniques, mammography poorly differentiated breasts containing less than 45% fat. When our analysis included only dense breasts (i.e., those containing less than 75% fat on MR images), the correlation coefficient decreased to .34. The largest discrepancies between mammography and MR imaging occurred in breasts that had 60-80% fat as measured on MR imaging. CONCLUSION: Fatty and fibroglandular tissue can be differentiated on MR images of the breast with high precision and accuracy, therefore allowing assessment of breast density. The conclusions of researchers who used mammographic density patterns should be reassessed.

Adipose Tissue↗
PubMed1995

MR imaging of the breast.

Studies suggest that magnetic resonance (MR) imaging may have a variety of roles in the detection and management of breast disease. However, because study methods and imaging techniques are not standard, there is still a great deal of uncertainty about its place in clinical practice. The authors review the current state of breast MR imaging and address a number of issues, including the basis for contrast material-enhanced imaging, techniques, and possible clinical roles, including treatment planning, evaluation of the posttreatment breast, evaluation of breast implants, characterization of breast masses, MR imaging-guided biopsy, and the potential for cancer screening. Although it is premature to recommend the routine use of breast MR imaging, contrast-enhanced MR imaging has potential as a comprehensive platform for the detection, localization, biopsy, and treatment of breast cancers.

Breast↗
PubMed1994

Controversies in breast MRI.

This article addresses some of the current controversies in breast magnetic resonance imaging (MRI), including (a) Is MR mammography a suitable magnetic resonance imaging (MRI), including (a) Is MR mammography a suitable name for breast MRI? (b) Do we need another breast-imaging exam (Is mammography really that bad?)? (c) What is the best technique for MRI of the breast? (d) Is fat suppression necessary? (e) Is MRI more sensitive than mammography for breast cancer detection? (f) Will MRI make a difference in patient outcome, and will it become a screening test? (g) What are the current indications for breast MRI? (h) Is MRI important for evaluation of the post-surgical breast? and (i) Should patients with radiographically dense breast undergo "screening" MRI?

Aged↗
PubMed1992

Improving the yield of biopsy for nonpalpable lesions of the breast.

Our early experience and frustration with needle localization biopsy of nonpalpable lesions of the breast led us to develop a protocol to improve diagnostic accuracy and management of patients with mammograms read as suspicious for malignancy. In this context and as part of the program, surgical and radiologic consultation is required prior to the decision to proceed with biopsy. In this article, our experience with that protocol is summarized and mammographic description with pathological findings is correlated. In a series of 200 consecutive patients who underwent biopsies, we have achieved a positive rate of 37 per cent. Only 2 per cent of those lesions with round, oval or lobulated borders were malignant, while irregular or spiculated lesions were malignant in 69 per cent of instances. We conclude that careful adherence to this protocol and to radiologic principles of contour analysis can substantially increase the yield of needle localization biopsy.

Adult↗
PubMed1991

Adjuvant post-operative radiotherapy in rectal cancer: results from the ANZ Bowel Cancer Trial (Protocol 8202).

In July 1982 the Gastrointestinal Section of The Clinical Oncological Society of Australia began a multicentre randomized trial to assess the value of post-operative pelvic radiotherapy in the local control of stage B and C carcinoma of the rectum. Patients who had undergone a potentially curative resection were randomized either to no further treatment (NO RT) or to pelvic radiotherapy (RT), 45 Gy in 25 fractions (plus a perineal boost of 5 Gy in 2 fractions after abdomino-perineal resection). The trial was prematurely terminated in December 1985 owing to slow accrual after 70 patients had been randomized: 36 patients to RT and 34 patients to NO RT. Two patients in each group were found to be ineligible after randomization and, for a variety of reasons, thirteen patients who were randomized to RT did not receive that treatment. The incidence of post-operative complications were comparable in both groups, indicating that radiotherapy produced no additional problems. Radiotherapy-related morbidity comprised mainly diarrhoea (grade 1 = 2/21; grade 2 = 5/21; grade 3 = 0/21; grade 4 = 1/21). There were no deaths due to radiotherapy and only one patient, with grade 4 diarrhoea, failed to complete the prescribed course of radiotherapy. After an average follow-up period of 52 months there were 15 local recurrences, 8 in the RT group and 7 in the NO RT group, giving an actuarial 2 year local recurrence rate of 16%. There was no difference in the time to local recurrence, either by randomization group (p = 0.50) or by actual treatment received (p = 0.91).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMedDate not supplied

MR-guided fine needle aspiration of breast lesions: initial experience.

OBJECTIVE: Fine needle aspiration (FNA) is a minimally invasive procedure that is used to obtain cytologic specimens of suspicious lesions in the breast. The goal of this study was to evaluate the logistics and limitations of MR-guided FNA using a prototype breast localization coil. MATERIALS AND METHODS: MR-guided FNAs were attempted on 18 lesions (detected on mammography and/or palpation) in 16 patients. Patients were prone with their breast compressed mediolaterally between two plates in a circularly polarized RF coil. Lesion position was determined by reference to fiducial markers that corresponded to a grid of holes placed at 5 mm intervals in the compression plate. FNA was performed with a 22G non-ferromagnetic needle. RESULTS: FNA was successful for 11 of 18 lesions (61%). Of the seven unsuccessful cases, there were four in which the lesions were too posteriorly placed to be accessed through the compression plate by the needle. Three cases were too anteriorly placed to be effectively immobilized and, although successfully localized, were insufficiently sampled by the FNA technique. CONCLUSION: MR-guided FNA is possible using a prototype breast localization device in a select group of patients. Current coil design limits its use in performing MR-guided FNA on the most anteriorly and posteriorly placed breast lesions. Unique requirements of FNA under MR guidance as compared to needle localization and biopsy have been identified. Modifications in localization hardware and cytology aspiration needles should overcome these restrictions.

Adolescent↗