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Biomedical subjects

Mark A Helvie

Publications and source records attributed to Mark A Helvie.

31 records · Page 2Linked to original sources
PubMed2004

An observer study comparing spot imaging regions selected by radiologists and a computer for an automated stereo spot mammography technique.

We are developing an automated stereo spot mammography technique for improved imaging of suspicious dense regions within digital mammograms. The technique entails the acquisition of a full-field digital mammogram, automated detection of a suspicious dense region within that mammogram by a computer aided detection (CAD) program, and acquisition of a stereo pair of images with automated collimation to the suspicious region. The latter stereo spot image is obtained within seconds of the original full-field mammogram, without releasing the compression paddle. The spot image is viewed on a stereo video display. A critical element of this technique is the automated detection of suspicious regions for spot imaging. We performed an observer study to compare the suspicious regions selected by radiologists with those selected by a CAD program developed at the University of Michigan. True regions of interest (TROIs) were separately determined by one of the radiologists who reviewed the original mammograms, biopsy images, and histology results. We compared the radiologist and computer-selected regions of interest (ROIs) to the TROIs. Both the radiologists and the computer were allowed to select up to 3 regions in each of 200 images (mixture of 100 CC and 100 MLO views). We computed overlap indices (the overlap index is defined as the ratio of the area of intersection to the area of interest) to quantify the agreement between the selected regions in each image. The averages of the largest overlap indices per image for the 5 radiologist-to-computer comparisons were directly related to the average number of regions per image traced by the radiologists (about 50% for 1 region/image, 84% for 2 regions/image and 96% for 3 regions/image). The average of the overlap indices with all of the TROIs was 73% for CAD and 76.8% +/- 10.0% for the radiologists. This study indicates that the CAD determined ROIs could potentially be useful for a screening technique that includes stereo spot mammography imaging.

Biophysical Phenomena↗
PubMed2004

Invasive cancers detected after breast cancer screening yielded a negative result: relationship of mammographic density to tumor prognostic factors.

PURPOSE: To evaluate common breast tumor prognostic characteristics, including estrogen receptor (ER) status, grade, size, and method of detection, in relationship to mammographic density. MATERIALS AND METHODS: The study involved 121 women who had negative results at both screening mammography and breast physical examination within 17 months before a diagnosis of breast cancer. Mammographic density was classified according to Breast Imaging Reporting and Data System patterns 1 through 4 (where 1 indicates a fatty breast and 4 indicates a dense breast). Axillary nodal status and tumor histologic ER status, histologic grade, size, stage, and method of detection (mammography alone, palpation alone, or both palpation and mammography) were analyzed by density category and tested for statistically significant differences across categories by using analysis of variance. RESULTS: Statistically significant differences (P <.05) by density category were found for the following variables: ER positivity (15 of 15 tumors in category 1 breasts, 32 of 41 tumors in category 2 breasts, 37 of 49 tumors in category 3 breasts, and eight of 16 tumors in category 4 breasts were ER positive), occurrence of grade 1 tumors (eight, 11, 19, and four tumors in category 1, category 2, category 3, and category 4 breasts, respectively, were grade 1), mean tumor size (11.3, 13.0, 14.7, and 19.7 mm for category 1, category 2, category 3, and category 4 breasts, respectively), detection with mammography alone (13, 31, 36, and four tumors in category 1, category 2, category 3, and category 4 breasts, respectively, were detected with mammography alone), and occurrence of stage I tumors (10, 25, 28, and five tumors in category 1, category 2, category 3, and category 4 breasts, respectively, were stage I). CONCLUSION: In women with negative results at clinical and mammographic screening within 17 months before breast tumor detection, subsequently diagnosed cancers tend to be ER negative, of higher grade, and larger in size in those with dense tissue patterns than in those with fat patterns.

Adult↗
PubMed2004

Small (< 2.0-cm) breast cancers: mammographic and US findings at US-guided cryoablation--initial experience.

PURPOSE: To determine the mammographic and ultrasonographic (US) findings at cryoablation of small solitary invasive breast cancers and compare them with presence of residual malignancy after treatment. MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. Nine patients with small solitary invasive breast cancers diagnosed at core biopsy were treated with US-guided cryoablation and a 2.7-mm cryoprobe. Mean cancer size was 12 mm (range, 8-18 mm); four were palpable. Tabletop argon gas-based cryoablation system with a double-freeze-thaw protocol was used to treat cancers in outpatient setting. Tumor sites were excised at lumpectomy 2-3 weeks after cryoablation. Findings at mammography and US before, during, and after cryoablation were assessed to categorize densities and masses on mammograms and masses on US images with Breast Imaging Reporting and Data System (BI-RADS); maximum cancer size was measured. Imaging findings and clinical breast examination data were compared with histologic findings from lumpectomy specimens to determine presence of intraductal or invasive cancer. RESULTS: With US guidance, ice balls (maximal mean size, 4.4 cm) were formed around cancers. Before excision, eight patients underwent mammography; all had new focal densities (maximum size, 2.5-5.0 cm) at cancer sites. Six patients underwent preexcisional US; 100% of them had new hyperechogenicity in tissue surrounding cancer site. Seven (78%) of nine patients had no residual cancer; specimens contained fat necrosis. One patient had a small focus of invasive cancer; one had extensive multifocal ductal carcinoma in situ. Patients with BI-RADS category 1 or 2 densities on mammograms or nonpalpable tumors had no residual malignancy. No residual invasive cancer occurred in tumors 17 mm or smaller or in cancers without spiculated margins at US. CONCLUSION: After cryoablation, there was increased echogenicity at US and increased density at mammography; these findings were observed in areas that approximated location and size of the ice ball. Tumor size, mammographic density, and US characteristics may be indicators of likelihood of complete cryoablation.

Adenocarcinoma, Mucinous↗
PubMed2004

Combination of digital mammography with semi-automated 3D breast ultrasound.

This paper describes work aimed at combining 3D ultrasound with full-field digital mammography via a semi-automatic prototype ultrasound scanning mechanism attached to the digital mammography system gantry. Initial efforts to obtain high x-ray and ultrasound image quality through a compression paddle are proving successful. Registration between the x-ray mammogram and ultrasound image volumes is quite promising when the breast is stably compressed. This prototype system takes advantage of many synergies between the co-registered digital mammography and pulse-echo ultrasound image data used for breast cancer detection and diagnosis. In addition, innovative combinations of advanced US and X-ray applications are being implemented and tested along with the basic modes. The basic and advanced applications are those that should provide relatively independent information about the breast tissues. Advanced applications include x-ray tomosynthesis, for 3D delineation of mammographic structures, and non-linear elasticity and 3D color flow imaging by ultrasound, for mechanical and physiological information unavailable from conventional, non-contrast x-ray and ultrasound imaging.

Adult↗
PubMed2002

Optimal neural network architecture selection: improvement in computerized detection of microcalcifications.

RATIONALE AND OBJECTIVES: The authors evaluated the effect of optimal neural network architecture selection on the performance of a computer-aided diagnostic system designed to detect microcalcification clusters on digitized mammograms. MATERIALS AND METHODS: The authors developed a computer program to detect microcalcification clusters automatically on digitized mammograms. Previously, they found that a properly selected and trained convolution neural network (CNN) could reduce false-positive (FP) findings and therefore improve the accuracy of microcalcification detection. In the current study, they evaluated the effectiveness of the CNN optimized with an automated optimization technique in improving the accuracy of the microcalcification detection program, comparing it with the manually selected CNN. An independent test data set was used, which included 472 mammograms selected from the University of South Florida public database and contained 253 biopsy-proved malignant clusters. RESULTS: At an FP rate of 0.7 cluster per image, the film-based sensitivity was 84.6% for the optimized CNN, compared with 77.2% for the manually selected CNN. For clusters imaged on both craniocaudal and mediolateral oblique views, a cluster could be considered detected when it was detected on one or both views. For this case-based approach, at an FP rate of 0.7 per image, the sensitivity was 93.3% for the optimized and 87.0% for the manually selected CNN. CONCLUSION: The classification of true and false signals is an important step in the microcalcification detection program. An optimized CNN can effectively reduce FP findings and improve the accuracy of the computer-aided detection system.

Breast Neoplasms↗
PubMed2002

Decreasing rate of fatty involution at screening mammography.

RATIONALE AND OBJECTIVES: This study was performed to document the perceived decrease in fatty involution at screening mammography during the past decade and evaluate the influence of hormone replacement therapy (HRT). MATERIALS AND METHODS: In December 1996, the mammograms of 261 consecutive screening patients with a comparison study obtained 5 years earlier were evaluated, and their breasts were categorized according to Breast Imaging Reporting and Data System categories for breast density. The women, aged 50-59 years, included 119 who had been receiving HRT for 0.25-15 years (mean, 3 years). From the files, 261 age-matched screening mammograms from 1986 were obtained; these patients also had comparison mammograms from 1981. Analysis of variance was used to determine differences between the 1980s group, the 1990s group receiving HRT, and the 1990s group not receiving HRT. Scheffé tests were used for post hoc comparisons. Stepwise regression analysis was used to evaluate the relative influence of age, decade, score of the first mammogram, and HRT. RESULTS: Breast density for the 1991 mammograms did not differ significantly from that in 1981 (P < .05). Initial breast density was the best predictor of final breast density in both decades (P < .001), regardless of HRT status. The change in breast density (toward fatty) over the 5-year interval in the 1980s (mean, 0.48) was significantly greater than that in both 1990s groups (mean for HRT group, 0.11; no HRT, 0.30; P < .05). CONCLUSION: These results confirm that breast density at screening mammography in the 1990s did not decrease with age at the same rate as in the 1980s, even in patients not receiving HRT.

Adipose Tissue↗
PubMed2002

Detection of Epstein-Barr virus in rapidly growing fibroadenomas of the breast in immunosuppressed hosts.

Fibroadenomas are the most common benign tumors of the female breast and are associated with a slight increase in the risk of subsequent breast cancer. Multiple fibroadenomas have been described in patients after renal transplantation and are thought to be secondary to drug-related growth stimulation. Epstein-Barr virus (EBV) has been detected in many neoplasms, including breast cancer. We set out to investigate whether EBV plays a role in the development of rapidly growing fibroadenomas in immunocompromised patients. We studied 19 fibroadenomas and one invasive ductal carcinoma that developed after organ transplantation or treatment for lupus erythematosus. As a control group we included 11 fibroadenomas from non-immunocompromised patients. DNA was amplified using polymerase chain reaction (PCR) of the EBV-encoded small RNA (EBER-2) DNA sequence. EBV latent membrane protein 1 (LMP-1) transcripts were amplified using reverse transcription (RT) PCR. Immunohistochemical (IHC) staining for LMP-1 protein was performed. A total of 9 out of 20 tumors (45%) were concordantly positive by PCR and IHC. IHC stained exclusively the epithelial cells. All the fibroadenomas in non-immunocompromised patients were negative for LMP-1 (Fisher's exact test P =.0006). These data suggest that EBV is associated with fibroadenomas in this immunosuppressed population and that the infection is specifically localized to epithelial cells. This is the first study suggesting a role for EBV in the pathogenesis of fibroadenomas.

Adult↗
PubMed2002

Improvement of computerized mass detection on mammograms: fusion of two-view information.

Recent clinical studies have proved that computer-aided diagnosis (CAD) systems are helpful for improving lesion detection by radiologists in mammography. However, these systems would be more useful if the false-positive rate is reduced. Current CAD systems generally detect and characterize suspicious abnormal structures in individual mammographic images. Clinical experiences by radiologists indicate that screening with two mammographic views improves the detection accuracy of abnormalities in the breast. It is expected that the fusion of information from different mammographic views will improve the performance of CAD systems. We are developing a two-view matching method that utilizes the geometric locations, and morphological and textural features to correlate objects detected in two different views using a prescreening program. First, a geometrical model is used to predict the search region for an object in a second view from its location in the first view. The distance between the object and the nipple is used to define the search area. After pairing the objects in two views, textural and morphological characteristics of the paired objects are merged and similarity measures are defined. Linear discriminant analysis is then employed to classify each object pair as a true or false mass pair. The resulting object correspondence score is combined with its one-view detection score using a fusion scheme. The fusion information was found to improve the lesion detectability and reduce the number of FPs. In a preliminary study, we used a data set of 169 pairs of cranio-caudal (CC) and mediolateral oblique (MLO) view mammograms. For the detection of malignant masses on current mammograms, the film-based detection sensitivity was found to improve from 62% with a one-view detection scheme to 73% with the new two-view scheme, at a false-positive rate of 1 FP/image. The corresponding cased-based detection sensitivity improved from 77% to 91%.

Algorithms↗
PubMed2002

Palpable breast thickening: role of mammography and US in cancer detection.

PURPOSE: To determine the frequency of breast carcinoma and ascertain the diagnostic yield of mammography and breast ultrasonography (US) in the detection of breast carcinoma in women with palpable breast thickening. MATERIALS AND METHODS: One hundred twenty-three consecutive cases of breast thickening (103 patients) during a 1-year period were reviewed. Experienced breast examiners prospectively identified patients with breast thickening. Results of diagnostic mammographic work-up, breast US, breast biopsy, and clinical follow-up were retrospectively reviewed. RESULTS: Six (5%) of 123 cases had a diagnosis of breast carcinoma; five (83%) of the six had invasive carcinoma. Mammography was performed in all cases, US in 77 (63%) cases. Mammographic sensitivity for invasive cancer detection was 60% (three of five cases), specificity was 94% (102 of 108 cases), and negative predictive value was 97% (102 of 105 cases). Sensitivity of US alone was 100% (two of two cases), specificity was 96% (65 of 68 cases), and negative predictive value was 100% (65 of 65 cases). The combined negative predictive value of mammography and US was 100%. Patients with prior biopsies at the site of palpable thickening accounted for most false-negative mammograms. Median time to initiate follow-up of patients in whom biopsy was not performed was 14 months. CONCLUSION: Breast cancer was discovered in 5% of women with palpable breast thickening. Women with negative mammograms and US scans are at low risk for cancer but should, in our opinion, be followed up at short-term intervals with clinical examination and imaging if biopsy is not elected by their surgeon or clinician.

Adult↗
PubMed2002

Mammographic screening of TRAM flap breast reconstructions for detection of nonpalpable recurrent cancer.

PURPOSE: To evaluate findings from routine mammographic screenings in patients with transverse rectus abdominis musculocutaneous (TRAM) flap reconstructions. MATERIALS AND METHODS: During a 25-month study period, 214 consecutive screening mammograms in 113 asymptomatic women (mean age, 51 years) with TRAM flap reconstructions were obtained. Mastectomies were performed for cancer in 106 (94%) of the 113 women and for prophylaxis in seven (6%). Prospectively, a Breast Imaging Reporting and Data System (BI-RADS) assessment category 1-5 was assigned to each mammogram. Surgical, medical, pathologic, and radiographic records were retrospectively reviewed. CIs were determined by the normal approximation to the binomial distribution. RESULTS: Seven (3%) of 214 examinations were BI-RADS category 4 or 5. Six (86%) of seven patients underwent biopsy. Two (33%) of these six biopsies demonstrated invasive ductal carcinoma. Cancer detection rate for mammography was 1.9% (two of 106) (95% CI: 0.33%, 7.32%) for women with reconstruction for breast cancer during the 2-year period. One (6%) of 16 BI-RADS category 3 examinations later proved to be invasive ductal carcinoma at follow-up. No interval cancer was discovered in 171 cases of BI-RADS category 1 or 2 examinations with 1-year follow-up. No cancers occurred in women who underwent prophylactic mastectomy. A biopsy positive predictive value of 33% (95% CI: 6%, 76%) was observed. CONCLUSION: Screening mammography of TRAM flap-reconstructed breasts enables detection of nonpalpable cancer before clinical examination.

Adult↗
PubMed2002

Breast cancer detection: evaluation of a mass-detection algorithm for computer-aided diagnosis -- experience in 263 patients.

PURPOSE: To evaluate the performance of a computer-aided diagnosis (CAD) mass-detection algorithm in marking preoperative masses. MATERIALS AND METHODS: Digitized mammograms were processed with an adaptive enhancement filter followed by a local border refinement stage. Features were then extracted from each detected structure and used to identify potential masses. The performance of the algorithm was evaluated in independent cases obtained from 263 patients from two institutions. Each case contained one or more pathologically proved breast masses. Contralateral mammograms obtained in the same patients that did not contain a visible lesion were used to estimate the CAD marker rate for the algorithm. The tradeoff between detection sensitivity and the number of CAD marks was analyzed in this study. RESULTS: Malignant masses were detected with the computer in 87% (135 of 156), 83% (130 of 156), and 77% (120 of 156) of the malignant cases at CAD marker rates of 1.5, 1.0, and 0.5 marks per mammogram, respectively. The difference between malignant mass-detection performance in subsets of cases collected at each institution was found to be less than 1%. The detection accuracy for benign masses was lower than that for malignant masses. CONCLUSION: This mass-detection algorithm had a high sensitivity for detection of malignant masses. It may be useful as a second opinion in mammographic interpretation.

Algorithms↗
PubMedDate not supplied

Outcome of men presenting with clinical breast problems: the role of mammography and ultrasound.

The purpose of this study was to determine the outcome of men presenting with clinical breast problems for breast imaging and to evaluate the role of mammography and ultrasound in the diagnosis of benign and malignant breast problems. We retrospectively reviewed clinical, radiographic, and pathologic records of 165 consecutive symptomatic men presenting to Breast Imaging over a 4 year period. We assessed the clinical indication for referral, mammographic findings, sonographic findings, histologic results, and clinical outcomes. Patients ranged in age from 22 to 96 years. Breast Imaging Reporting and Data System (BI-RADS) category 4 and 5 mammograms and solid sonographic masses were considered suspicious for malignancy. Six of 165 men (4%) had primary breast carcinoma, which were mammographically suspicious in all 6 (100%). Five were invasive ductal carcinoma and one was ductal carcinoma in situ (DCIS). Of 164 mammograms, 20 (12%) were suspicious. Six were cancer and 14 were benign. Clinical follow-up for 2 years or biopsy results were available for 138 of the 165 men (84%). Twelve with benign mammographic findings had benign biopsies. All men with benign mammography not undergoing biopsy were cancer free. Sensitivity for cancer detection (mammography) was 100% and specificity was 90%. Positive predictive value (mammography) was 32% (6 of 19) and the negative predictive value was 100%. Sonography was performed in 68 of the 165 men (41%). Three of three cancers (100%) were solid sonographic masses. There were 9 of 68 false-positive examinations (13%). Sensitivity and negative predictive value for cancer detection (ultrasound) was 100% and specificity was 74%. The most common clinical indication for referral was mass/thickening (56%). Mammography had excellent sensitivity and specificity for breast cancer detection and should be included as the initial imaging examination of men with clinical breast problems. The negative predictive value of 100% for mammography suggests that mammograms read as normal or negative need no further examination if the clinical findings are not suspicious. A normal ultrasound in these men confirms the negative predictive value of a normal mammogram.

Adult↗