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Biomedical subjects

D C Sullivan

Publications and source records attributed to D C Sullivan.

At least 37 records · Page 2Linked to original sources
PubMed1998

Disparity mapping applied to sonography of the breast: technical note.

A two-dimensional sonoelastographic technique called "disparity mapping" was applied to breast sonographic examinations in eight patients to test discrimination between benign and malignant lesions. With probe compression, pairs of gray-scale sonographic scans were obtained about 1 second apart. The disparity mapping procedure calculated the apparent displacement of the speckle pattern about each point in the image and presented that information in the form of a disparity map. Findings were consistent with a firm lesion in two of the three cancers, were indistinguishable from normal tissue in all three fibroadenomas, were indistinguishable from normal findings in one cyst, and showed no disparity in one cyst because it had few internal echoes.

Adult↗
PubMed1997

MR imaging of ductal carcinoma in situ.

PURPOSE: To investigate the ability of magnetic resonance (MR) imaging to depict ductal carcinoma in situ (DCIS). MATERIALS AND METHODS: Between January 1992 and April 1996, 330 women underwent MR imaging before excisional biopsy. Of these, 101 women had carcinoma, 19 of whom had DCIS. The MR imaging findings in the 19 women were reviewed. RESULTS: Thirteen of 19 patients had pure DCIS. The mean lesion diameter was 10 mm (range, 2-22 mm). MR imaging enabled identification of DCIS in 10 (77%) of the 13 cases as ductal enhancement (n = 6), regional enhancement (n = 3), or a peripherally enhancing mass (n = 1). The three lesions not identified had a mean diameter of 3.7 mm. Six of 19 patients had both DCIS and an invasive cancer. In four of these patients, DCIS was identified only at MR imaging (mean diameter, 3 mm). In two of six patients, DCIS was not identified at MR imaging. CONCLUSION: MR imaging can depict mammographically visible and occult foci of DCIS. Some small foci of DCIS detected at mammography and histologic examination, however, may be occult at MR imaging.

Adult↗
PubMed1997

Breast carcinoma: MR imaging before re-excisional biopsy.

PURPOSE: To investigate the role of magnetic resonance (MR) imaging in the examination of patients after excisional biopsy of breast carcinoma before re-excision. MATERIALS AND METHODS: Forty-seven patients underwent contrast material-enhanced MR imaging after initial excisional biopsy of breast carcinoma before further surgery. RESULTS: The positive predictive value of MR imaging for predicting residual disease was 82%; the negative predictive value was 61%. Fourteen patients had multifocal (n = 6) or diffuse (n = 8) carcinoma. The extent of tumor was correctly identified with MR imaging alone in nine of the 14 patients, with both mammography and MR imaging in three patients, with mammography alone in one patient, and with no imaging modality in one patient. In four of the 14 patients, management was altered from re-excision to mastectomy (n = 3) or from breast-conservation therapy to mastectomy (n = 1). CONCLUSION: MR imaging has a high positive predictive value for predicting residual tumor after excisional biopsy. The identification of mammographically and clinically unsuspected multifocal or extensive residual tumor may lend support for mastectomy rather than re-excision. However, false-negative findings due to postsurgical changes and false-positive findings due to enhancement of granulation tissue and benign breast tissue remain limitations.

Adult↗
PubMed1996

Variability in the interpretation of screening mammograms by US radiologists. Findings from a national sample.

OBJECTIVE: To evaluate the effectiveness of screening mammography by estimating the variability in radiologists' ability to detect breast cancer within the US population of radiologists at mammography centers accredited by the American College of Radiology. METHODS: A two-way sample survey design was used as follows. Fifty mammography centers having an American College of Radiology-accredited unit were randomly sampled from across the United States. One hundred eight radiologists from these centers gave blinded interpretation to the same set of 79 randomly selected screening mammograms. The mammograms were from women who had been screened at a large screening center. Before their sampling, these women had been stratified by their breast disease status, established either by biopsy or by 2-year follow-up. Rates of biopsy recommendations were summarized by the mean, median, minimum, maximum, and range of sensitivity and specificity. Overall cancer detection ability was summarized by similar statistics for receiver operating characteristic curve areas. Ninety-five percent lower confidence bounds on the ranges in accuracy measures were established by boo-strapping. RESULTS: There is a range of at least 40% among US radiologists in their screening sensitivity. There is a range of at least 45% in the rates at which women without breast cancer are recommended for biopsy. As indicated by receiver operating characteristic curve areas, the ability of radiologists to detect cancer mammograms varies by as much as 11%. CONCLUSIONS: Our findings indicate that there is wide variability in the accuracy of mammogram interpretation in the population of US radiologists. Current accreditation programs that certify the technical quality of radiographic equipment and images but not the accuracy of the interpretation given to mammograms may not be sufficient to help mammography fully realize its potential to reduce breast cancer mortality.

Breast Diseases↗
PubMed1996

Effect of human variability on independent double reading in screening mammography.

RATIONALE AND OBJECTIVES: To demonstrate the range of gains and losses that radiologists might experience from independent double reading in screening mammography. METHODS: From a national random sample of radiologists, the authors formed 131 pairs. For each radiologist, the authors analyzed the increase relative to his or her individual true-positive rate (TPR) or false-positive rate (FPR), number of additional cancers detected, and change to negative biopsy rate that would result from independent double reading after pairing. RESULTS: The average radiologist can expect an 8%-14% gain in TPR and a 4%-10% increase in FPR with pairing. For some radiologists, double reading increased the TPR with a small concomitant increase in FPR. Other radiologists, however, realized small gains in TPR with large increases in FPR. Adding the reading from a more experienced radiologist did not necessarily improve the TPR of a radiologist with less experience. CONCLUSION: Radiologists can form complementary and noncomplementary pairs for double reading. Use of this procedure must be decided on an individual basis.

Breast Neoplasms↗
PubMed1996

High-resolution MR imaging of the breast: clinical context.

Preliminary investigation into magnetic resonance (MR) imaging as a breast imaging technique has demonstrated several promising roles for this modality when used as an adjunct to mammography for the detection and diagnosis of breast cancer. There are many technical factors that must be considered, including high resolution, rapid imaging, fat suppression, and localization and biopsy capability. Potential clinical applications include differentiating benign from malignant lesions, detecting cancer when results of clinical examination or conventional imaging are equivocal, detecting cancer recurrence after breast conservation treatment, staging newly diagnosed breast cancer, and detecting occult cancer in patients presenting with axillary node metastasis. Pitfalls include false-positive and false-negative results. Awareness of the strengths and limitations of MR imaging of the breast will facilitate integration of this technique into the work-up of patients with suspicious breast lesions.

Adult↗
PubMed1995

Seromas in residual fibrous capsules after explantation: mammographic and sonographic appearances.

PURPOSE: To evaluate the mammographic and sonographic findings associated with seromas that develop in residual fibrous capsules after explantation of breast prostheses. MATERIALS AND METHODS: Preoperative and postoperative mammograms were reviewed in 86 patients (mean age, 51 years; age range, 24-71 years) who had undergone surgical explantation of breast prostheses. Six seromas were found in four patients 46-68 years of age. Imaging findings were correlated with surgical and laboratory results for three seromas. A presumptive diagnosis was made of the other three lesions. RESULTS: Mammograms demonstrated all seromas as large, elliptic, water-opacity masses, some with well-circumscribed and some with irregular borders. Sonograms showed thin, compressible masses, two of which were flat and anechoic and one of which was hypoechoic. Three patients' images were initially misinterpreted, leading to excision of two seromas and aspiration of one. Seromas were not identified in patients whose implants were removed by means of complete capsulectomy. CONCLUSION: Radiologists must be aware of the imaging findings associated with seromas and of a patient's surgical history to avoid biopsy of benign lesions.

Aged↗
PubMed1994

Prediction of breast cancer malignancy using an artificial neural network.

BACKGROUND: An artificial neural network (ANN) was developed to predict breast cancer from mammographic findings. This network was evaluated in a retrospective study. METHODS: For a set of patients who were scheduled for biopsy, radiologists interpreted the mammograms and provided data on eight mammographic findings as part of the standard mammographic workup. These findings were encoded as features for an ANN. Results of biopsies were taken as truth in the diagnosis of malignancy. The ANN was trained and evaluated using a jackknife sampling on a set of 260 patient records. Performance of the network was evaluated in terms of sensitivity and specificity over a range of decision thresholds and was expressed as a receiver operating characteristic curve. RESULTS: The ANN performed more accurately than the radiologists (P < 0.08) with a relative sensitivity of 1.0 and specificity of 0.59. CONCLUSIONS: An ANN can be trained to predict malignancy from mammographic findings with a high degree of accuracy.

Algorithms↗
PubMed1994

Needle core biopsy of mammographic lesions.

Needle core biopsy and fine-needle aspiration cytology (FNAC) provide histologic diagnoses in a wide variety of clinical settings. In breast disease, surgeons have used these techniques to evaluate palpable masses for many years. In recent years, radiologists have used image-guided adaptations of these two techniques to evaluate mammographically detected lesions.

Biopsy, Needle↗
PubMed1993

Impact of patient-controlled compression on the mammography experience.

The authors tested the hypothesis that giving women control over the compression portion of the mammography examination results in a less painful experience, greater overall patient satisfaction, and a radiographic image as good as that produced by means of technologist-controlled compression. One hundred nine women undergoing screening mammography at a hospital-based outpatient clinic were studied. Each underwent two-view, screen-film mammography performed in routine fashion except that, by random assignment, one breast was compressed by the technologist and the other breast, by the patient. Patient-controlled compression was significantly (P = .003) less painful than technologist-controlled compression. Overall patient satisfaction (96% [105 of 109]) and willingness to repeat the experience were extremely high. The majority of images (93.5% [202 of 216]) were rated as having good to excellent compression. With minimal patient education, self-compression resulted in an image at least as good as that produced with technologist-applied compression. Further study of this technique is warranted.

Adult↗
PubMed1992

The natural history of mammographic calcifications subjected to interval follow-up.

The purpose of this investigation was to determine the natural history and risk of malignancy associated with isolated indeterminate microcalcifications subjected to interval follow-up. During a 2-year study, 91 patients were identified with indeterminate microcalcifications alone. Specific roentgenographic features of the calcifications were evaluated on initial and follow-up mammograms. During a mean follow-up of 36 months, 19 (21%) of the women exhibited mammographic changes. Ten patients (11%) with suspicious changes underwent a needle-directed biopsy 6 to 30 months after the initial mammographic screening. Five women (5.5%) were diagnosed as having breast carcinoma; three had invasive ductal carcinoma and two had purely intraductal lesions. Four patients had axillary lymph node dissections and no metastatic disease was found. We found no significant differences in the roentgenographic features associated with malignant vs benign lesions apart from an increased overall estimation of the probability of malignancy rating in the five patients with breast carcinoma. We recommend that patients be followed up with mammography at regular intervals for at least 18 months following recognition of indeterminate microcalcifications.

Aged↗
PubMed1992

Two dimensional ultrasonic beam distortion in the breast: in vivo measurements and effects.

Two dimensional arrival time data was obtained for the propagation of ultrasound across the breasts of 7 female volunteers. These profiles were extracted through the use of cross-correlation measurements and a simulated annealing process that maintained phase closure while aligning the data. The phase aberration measured in two dimensions had a larger magnitude than previously reported phase aberration measured in one dimension in the breast. A point spread function generation computer program was used to demonstrate the system response degrading effects of the measured phase aberration and the usefulness of current one dimensional phase aberration correction techniques. The results indicate that two dimensional correction algorithms are necessary to restore the system performance losses due to phase aberration.

Female↗
PubMed1991

Evaluation of acute renal failure with magnetic resonance imaging using gradient-echo and Gd-DTPA.

Detection of acute renal failure (ARF) using fast-scan magnetic resonance imaging (MRI) with Gd-DTPA was studied in a dog model. ARF was produced in five dogs by infusion of norepinephrine (0.75 micrograms/kg/min) into the renal arteries for 40 minutes. MRI was performed 1 hour later and compared with baseline (pre-ARF) MRI. There was no significant difference in the ratios of signal intensity-vs.-time curves from 0 to 35 seconds after injection of Gd-DTPA. However, a difference between the outer and inner medulla was significant in the time period of 5 to 20 minutes after Gd-DTPA injection. These later signal intensity differences by fast-scan (gradient-echo) technique may be useful in the evaluation of ARF.

Acute Kidney Injury↗
PubMed1991

Positron emission tomography in neuropsychiatry.

Positron emission tomography (PET) allows high-resolution, three-dimensional evaluation of regional brain metabolic activity and neurotransmitter function. This imaging technique has been applied increasingly in psychiatric research and may yield new information regarding the neural mechanisms of several mental disorders. This article is an overview of PET studies conducted on schizophrenia, affective disorders, and anxiety disorders. Although this research is in the preliminary stage with some inconsistent findings, general trends have emerged that clearly warrant further investigation. These trends are discussed in light of relevant methodological and theoretical issues. Potential directions for future PET research are reviewed.

Anxiety Disorders↗
PubMed1991

The impact of acoustic velocity variations on target detectability in ultrasonic images of the breast.

Experimentally obtained ultrasonic phase aberration profiles in the breast were used to investigate the impact of acoustic velocity variations on images of simulated breast lesions. The imaging properties of several phased-array transducers with varying frequencies and geometries were studied as phase error profiles of increasing magnitude were introduced. The targets studied were anechoic lesions of various sizes. The results indicate that phase aberrations significantly degrade the contrast of ultrasonic breast images, especially for high-resolution scanning systems.

Acoustics↗