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Biomedical subjects

Laurie L Fajardo

Publications and source records attributed to Laurie L Fajardo.

17 recordsLinked to original sources
PubMed2007

Breast MRI lesion classification: improved performance of human readers with a backpropagation neural network computer-aided diagnosis (CAD) system.

PURPOSE: To develop and test a computer-aided diagnosis (CAD) system to improve the performance of radiologists in classifying lesions on breast MRI (BMRI). MATERIALS AND METHODS: A CAD system was developed that uses a semiautomated segmentation method. After segmentation, 42 features based on lesion shape, texture, and enhancement kinetics were computed, and the 13 best features were selected and used as inputs to a backpropagation neural network (BNN). The BNN was trained and tested using the leave-one-out method on 80 BMRI lesions (37 benign, 43 malignant). Lesion histopathology was used as the reference standard. Five human readers classified the 80 lesions first without and then with CAD assistance. The performance of the computer classifier and the human readers was assessed using receiver operating characteristic curves; the performance of the human readers was also evaluated using multireader multicase (MRMC) analysis. RESULTS: The performance of the human readers significantly improved when aided by the CAD system (P < 0.05). MRMC analysis showed that human reader performance with and without CAD system assistance can be generalized to the population of cases (P < 0.001). CONCLUSION: A CAD system based on lesion morphology and enhancement kinetics can improve the performance of human readers in classifying lesions on breast MRI.

Breast Neoplasms↗
PubMed2006

Quality control for digital mammography: part II. Recommendations from the ACRIN DMIST trial.

The Digital Mammography Imaging Screening Trial (DMIST), conducted under the auspices of the American College of Radiology Imaging Network (ACRIN), is a clinical trial designed to compare the accuracy of digital versus screen-film mammography in a screening population [E. Pisano et al., ACRIN 6652-Digital vs. Screen-Film Mammography, ACRIN (2001)]. Part I of this work described the Quality Control program developed to ensure consistency and optimal operation of the digital equipment. For many of the tests, there were no failures during the 24 months imaging was performed in DMIST. When systems failed, they generally did so suddenly rather than through gradual deterioration of performance. In this part, the utility and effectiveness of those tests are considered. This suggests that after verification of proper operation, routine extensive testing would be of minimal value. A recommended set of tests is presented including additional and improved tests, which we believe meet the intent and spirit of the Mammography Quality Standards Act regulations to ensure that full-field digital mammography systems are functioning correctly, and consistently producing mammograms of excellent image quality.

Breast↗
PubMed2006

Cone-beam mammo-computed tomography from data along two tilting arcs.

Over the past several years there has been an increasing interest in cone-beam computed tomography (CT) for breast imaging. In this article, we propose a new scheme for theoretically exact cone-beam mammo-CT and develop a corresponding Katsevich-type reconstruction algorithm. In our scheme, cone-beam scans are performed along two tilting arcs to collect a sufficient amount of information for exact reconstruction. In our algorithm, cone-beam data are filtered in a shift-invariant fashion and then weighted backprojected into the three-dimensional space for the final reconstruction. Our approach has several desirable features, including tolerance of axial data truncation, efficiency in sequential/parallel implementation, and accuracy for quantitative analysis. We also demonstrate the system performance and clinical utility of the proposed technique in numerical simulations.

Algorithms↗
PubMed2005

Diagnostic performance of digital versus film mammography for breast-cancer screening.

BACKGROUND: Film mammography has limited sensitivity for the detection of breast cancer in women with radiographically dense breasts. We assessed whether the use of digital mammography would avoid some of these limitations. METHODS: A total of 49,528 asymptomatic women presenting for screening mammography at 33 sites in the United States and Canada underwent both digital and film mammography. All relevant information was available for 42,760 of these women (86.3 percent). Mammograms were interpreted independently by two radiologists. Breast-cancer status was ascertained on the basis of a breast biopsy done within 15 months after study entry or a follow-up mammogram obtained at least 10 months after study entry. Receiver-operating-characteristic (ROC) analysis was used to evaluate the results. RESULTS: In the entire population, the diagnostic accuracy of digital and film mammography was similar (difference between methods in the area under the ROC curve, 0.03; 95 percent confidence interval, -0.02 to 0.08; P=0.18). However, the accuracy of digital mammography was significantly higher than that of film mammography among women under the age of 50 years (difference in the area under the curve, 0.15; 95 percent confidence interval, 0.05 to 0.25; P=0.002), women with heterogeneously dense or extremely dense breasts on mammography (difference, 0.11; 95 percent confidence interval, 0.04 to 0.18; P=0.003), and premenopausal or perimenopausal women (difference, 0.15; 95 percent confidence interval, 0.05 to 0.24; P=0.002). CONCLUSIONS: The overall diagnostic accuracy of digital and film mammography as a means of screening for breast cancer is similar, but digital mammography is more accurate in women under the age of 50 years, women with radiographically dense breasts, and premenopausal or perimenopausal women. (ClinicalTrials.gov number, NCT00008346.)

Adult↗
PubMed2005

Ultrasound-guided microwave imaging of breast cancer: tissue phantom and pilot clinical experiments.

Microwave imaging promises high contrast between tumor and normal breast tissues, but its spatial resolution is limited. Here, we present a multimodality approach for high-resolution microwave imaging, where microwave image reconstruction is structurally guided by ultrasound imaging. The combined imaging concept is demonstrated using tissue phantom measurements obtained from a 16 x 15 transmitter/receiver microwave imaging system and a modified B-mode ultrasound system. With the geometry of the target and background known a priori from ultrasound, successful dielectric property images are recovered using a finite element-based reconstruction algorithm. We show that a target as small as 1.2 mm in diameter can be imaged with the multimodality approach, whereas it is impossible to detect such a small-size object using microwave imaging alone. The pilot clinical studies on two cases suggest that breast tumors can be much more accurately detected by the multimodality method.

Algorithms↗
PubMed2005

Free-response receiver operating characteristic evaluation of lossy JPEG2000 and object-based set partitioning in hierarchical trees compression of digitized mammograms.

PURPOSE: To assess the effects of two irreversible wavelet-based compression algorithms--Joint Photographic Experts Group (JPEG) 2000 and object-based set partitioning in hierarchical trees (SPIHT)--on the detection of clusters of microcalcifications and masses on digitized mammograms. MATERIALS AND METHODS: The use of the images in this retrospective image-collection study was approved by the institutional review board, and patient informed consent was not required. One hundred twelve mammographic images (28 with one or two clusters of microcalcifications, 19 with one mass, 17 with both abnormal findings, and 48 with normal findings) obtained in 60 women who ranged in age from 25 to 79 years were digitized and compressed at 40:1 and 80:1 by using the JPEG2000 and object-based SPIHT methods. Five experienced radiologists were asked to locate and rate clusters of microcalcifications and masses on the original and compressed images in a free-response receiver operating characteristic (FROC) data acquisition paradigm. Observer performance was evaluated with the jackknife FROC method. RESULTS: The mean FROC figures of merit for detecting clusters of microcalcifications, masses, and both radiographic findings on uncompressed images were 0.80, 0.81, and 0.72, respectively. With object-based SPIHT 80:1 compression, the corresponding values were larger than the values for uncompressed images by 0.005, 0.009, and -0.005, respectively. The 95% confidence interval for the differences in figures of merit between compressed and uncompressed images was -0.039, 0.033 for the microcalcification finding; -0.055, 0.034 for the mass finding; and -0.039, 0.030 for both findings. Because each of these confidence intervals includes zero, no significant difference in detection accuracy between uncompressed and object-based SPIHT 80:1 compression was observed at a P value of 5%. The F test of the null hypothesis that all of the modes (uncompressed and four compressed modes) were equivalent yielded the following results: F = 0.255, P = .903 for the microcalcification finding; F = 0.340, P = .848 for the mass finding; and F = 0.122, P = .975 for both findings. CONCLUSION: To within the accuracy of these measurements, lossy compression of digital mammographic data at 80:1 with JPEG2000 or the object-based SPIHT algorithm can be performed without decreasing the rate of detection of clusters of microcalcifications and masses.

Adult↗
PubMed2004

Adrenal adenoma with organizing hematoma: diagnostic dilemma at MRI.

We report a case of adrenal adenoma with organizing hematoma mimicking hemangioma on magnetic resonance imaging (MRI). The lesion demonstrated heterogeneous hyperintensity on heavily T2-weighted images. On dynamic contrasted-enhanced MRI, the lesion demonstrated early, patchy peripheral enhancement with subsequent fill-in that persisted. Chemical shift gradient-echo images failed to demonstrate the presence of intracellular lipid. Magnetic resonance imaging failed to characterize the lesion, and an erroneous preoperative diagnosis of adrenal hemangioma was made. Although the MRI findings reflected the organized hematoma with abundant vascular spaces, our case emphasizes the point that the MRI characteristics of intratumoral hemorrhage may overlap with those of adrenal hemangioma and chronic expanding hematoma.

Adrenal Cortex Neoplasms↗
PubMed2004

Stereotactic and sonographic large-core biopsy of nonpalpable breast lesions: results of the Radiologic Diagnostic Oncology Group V study.

RATIONALE AND OBJECTIVES: To determine the diagnostic accuracy of stereotactically and sonographically guided core biopsy (CB) for the diagnosis of nonpalpable breast lesions. MATERIALS AND METHODS: Twenty-two institutions enrolled 2,403 women who underwent imaging-guided fine needle aspiration followed by imaging-guided large-CB of nonpalpable breast abnormalities. All mammograms were reviewed for study eligibility by one of two breast imaging radiologists. The protocol for image-guided biopsy, using either ultrasound (USCB) or stereotactic (SCB) guidance, was standardized at all institutions and all biopsy specimens were over-read by one of three expert pathologists. Patients with atypical ductal hyperplasia (ADH), atypical lobular hyperplasia, or lobular neoplasia on CB underwent surgical excision. Those with negative CB but suspicious ("discordant") pre-biopsy mammography also underwent surgical excision. Patients having a negative CB that was concordant with the pre-biopsy mammography suspicion were assigned to follow-up mammography at 6, 12, and 24 months following CB. RESULTS: A gold standard diagnosis based on definitive histopathologic diagnosis, mammography follow-up, or an imputed gold standard diagnosis was established for 1,681 patients. Of 310 cases with a gold standard diagnosis of invasive breast carcinoma, 261 (84.2%) were invasive carcinoma, 31 (10%) were ductal carcinoma in situ (DCIS), four (1.3%) were ADH, one (0.3%) was a non-breast cancer, and 13 (4.2%) were benign on CB. For 138 cases with a gold standard diagnosis of DCIS, 113 (81.9%) were DCIS, 20 (14.5%) were ADH, and five (3.6%) were benign on CB. For 57 cases (13 masses, 44 calcifications) with an initial CB diagnosis of ADH, atypical lobular hyperplasia or lobular neoplasia, 20 (35.1%) had a gold standard diagnosis of DCIS (4 masses, 16 calcifications) and four (7.0%) had a gold standard diagnosis of invasive cancer (4 calcifications). Of 144 cases (22 masses, 122 calcifications) with an initial CB diagnosis of DCIS, 31 (21.5%) had a gold standard diagnosis of invasive cancer (10 masses, 21 calcifications). The sensitivity, specificity and accuracy for CB by either imaging guidance method in this trial were .91, 1.00, and .98, respectively. The sensitivity, predictive value negative, and accuracy of CB for diagnosing masses (.96, .99, and .99, respectively) were significantly greater (P < .001) than for calcifications (.84, .94, and .96, respectively). The sensitivity (.89) of SCB for diagnosing all lesions was significantly lower (P = 0.029) than that of USCB (.97) because of the preponderance of calcifications biopsied by SCB versus USCB. There was no difference between USCB and SCB in sensitivity, predictive value negative, or accuracy for the diagnosis of masses (97.3, 98.9, and 99.2, respectively for USCB; 95.6, 98.5, and 98.9 respectively for SCB). CONCLUSION: Percutaneous, imaged-guided core breast biopsy is an accurate diagnostic alternative to surgical biopsy in women with mammographically detected suspicious breast lesions.

Adult↗
PubMed2004

Differentiation of cysts from solid tumors in the breast with diffuse optical tomography.

RATIONALE AND OBJECTIVES: Near-infrared diffuse optical tomography (DOT) is an emerging imaging technology that has the potential to offer enhanced contrast resolution over the existing technologies for detection and diagnosis of breast cancer. Thus far, the clinical evaluation of DOT has been largely limited to solid tumors. A pilot clinical study focused on DOT imaging of breasts with cysts is presented. MATERIALS AND METHODS: Six cases were studied using the recently developed compact, parallel-detection DOT system. Images characterizing the tissue absorption and scattering were obtained with a finite element-based reconstruction algorithm. The optical images were compared with the mammograms and sonograms. In one case, in vitro measurements of optical properties were conducted for the fluid obtained from needle aspiration. RESULTS: Substantial contrast between cyst and adjacent parenchyma is observed. For the six cases evaluated, the locations and sizes of cysts imaged optically are accurate and consistent with the mammographic and sonographic findings. For the case that aspiration was performed, the absorption and scattering coefficients imaged in the cyst region are quantitatively accurate compared with that measured in vitro from the fluid aspirated. CONCLUSION: This pilot study shows that cysts ranging from 1-4 cm in diameter can be quantitatively imaged. They can be differentiated from solid breast tumors because cysts generally demonstrate lower absorption and scattering coefficients compared with the surrounding normal tissue, whereas solid tumors show concurrent higher absorption and scattering related to the normal tissue.

Adult↗
PubMed2004

Diagnostic agreement in the evaluation of image-guided breast core needle biopsies: results from a randomized clinical trial.

BACKGROUND: Image-guided core needle biopsies (CNBs) are commonly used as the initial sampling method for nonpalpable, mammographically detected breast lesions. Although prior studies have shown that this procedure is a highly sensitive and accurate method for the detection of breast cancer, the level of diagnostic agreement between pathologists in the analysis of CNB has not been previously studied in detail. METHODS: To address this, we reviewed the pathologic findings in 2004 CNB from patients enrolled in the Radiologic Diagnostic Oncology Group 5 study, a randomized, multicenter trial designed to determine the role of CNB and fine needle aspiration biopsy in the evaluation of nonpalpable breast lesions. Slides of CNB specimens were initially diagnosed by pathologists at the 22 participating institutions (local diagnosis) and were then sent to the study pathologists for central review (central diagnosis). Local and central diagnoses were compared. RESULTS: Overall, the central diagnosis and local diagnosis were concordant in 1925 cases (96%), indicating an excellent level of agreement by kappa statistic analysis (kappa = 0.90; 95% confidence interval 0.88-0.92). The level of agreement between local and central pathologists did not vary with the image guidance system (stereotactic mammography vs. ultrasound) or with the mammographic findings (soft tissue density vs. microcalcifications). The level of diagnostic agreement observed for CNB was comparable to that observed among 596 open surgical biopsies obtained from patients in this study and subjected to central pathology review (93% agreement; kappa = 0.89, 95% confidence interval 0.86-0.92). CONCLUSIONS: The level of diagnostic agreement in interpretation of breast CNB is extremely high among pathologists and is comparable to that seen for open surgical biopsy.

Biopsy, Needle↗
PubMed2004

Portal vein occlusion with aberrant left gastric vein functioning as a hepatopetal collateral pathway.

A rare case of an aberrant left gastric vein functioning as a hepatopetal collateral as a result of portal vein occlusion is presented herein. The portal venous phase of multislice computed tomography clearly demonstrated this anatomic variation and provided a reliable vascular "road map" for percutaneous transhepatic portal venous stent placement. Portal hypertension associated with extensive gastrojejunal varices improved dramatically after stent placement.

Adult↗
PubMed2003

In vivo breast imaging with diffuse optical tomography based on higher-order diffusion equations.

We report on in vivo absorption and scattering imaging of a human breast cyst and implant, using a reconstruction algorithm based on our third-order diffusion equations. To validate these in vivo images, a series of phantom experiments were conducted, in which we used low-absorbing and low-scattering heterogeneities to mimic a breast cyst or implant. These heterogeneities or targets were composed of pure water or a mixture of water and very dilute Intralipid (0.05% and 0.1%). The phantom experiment confirmed the quantitative imaging capability of our improved algorithm for reconstructing heterogeneities where the conventional diffusion approximation is inadequate. Pilot clinical results from female volunteers indicate that enhanced diffuse optical tomography can quantitatively image findings such as breast cysts or implants in which the absorption and scattering coefficients are usually low.

Adult↗
PubMed2003

Radiology residency eCurriculum developed in-house: evaluation of benefits and weaknesses.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate residents' use of a radiology curriculum CD-ROM designed to provide ready access to the department's curricula, study materials, and Internet resources. MATERIALS AND METHODS: A survey questionnaire eliciting feedback about the usability and value of the CD-ROM, as well as suggestions for future modifications in its content, was distributed to radiology residents (n = 26) in the authors' training program. Twenty-three (88%) of the residents responded to the survey. RESULTS: Eighteen (78%) of the 23 respondents reported having used the CD-ROM at least once, and 22 (96%) considered the CD-ROM an asset to the residency program. Fourteen (61%) identified the centralization of important information as the greatest benefit of the CD-ROM. Nonetheless, a majority continued to rely on more traditional methods of obtaining information essential to their work and studies. Twelve (52%) of the 23 residents reported that daily use of the material stored on the CD-ROM would be encouraged by placing it on a departmental intranet, while seven (30%) preferred the addition of dedicated computers and the provision of study space in the department. CONCLUSION: The CD-ROM has not been fully integrated into the residency program. The greatest obstacle to its use is the lack of computer resources in the department.

Attitude to Computers↗
PubMed2003

Digital mammography: a review of technical development and clinical applications.

For detecting and diagnosing breast cancer at its earliest stage, mammography is the most sensitive technique currently available and is therefore the method of choice. Screen-film mammography has been used successfully as a screening test for breast cancer for > 2 decades. However, conventional mammography has substantial limitations and, therefore, digital mammography systems have been developed to improve image quality and overcome the limitations of screen-film technique limitations. Herein we discuss the differences between screen-film and digital mammography systems and the processes related to digital mammography that differ from conventional mammography, including detector technology, digital image formation, image processing, image display, and image archival. Finally, we review the results from currently available clinical trials regarding the performance of digital mammography and discuss clinical implications such as cost-effectiveness.

Breast Neoplasms↗
PubMed2002

Near-infrared optical imaging of the breast with model-based reconstruction.

RATIONALE AND OBJECTIVES: Near-infrared diffuse optical imaging may offer enhanced contrast resolution over that of the existing technologies for detection and diagnosis of breast cancer. The authors report quantitative absorption and scattering images of the human breast with model-based reconstruction methods using near-infrared continuous-wave tomographic data. MATERIALS AND METHODS: An automatic, multichannel optical imaging system was used to image the breasts of nine women: four with infiltrating ductal carcinomas, one with infiltrating lobular carcinoma, one with fibroadenoma, and three control subjects with no breast lesion. The image reconstruction methods are centered on the finite element solution of photon diffusion in breast tissue. RESULTS: Substantial contrast between tumor and adjacent parenchyma was observed. Images of the control subjects showed homogeneous optical features. In the six women with breast lesions, the locations and sizes of tumors imaged optically were accurate and consistent with the mammographic findings. CONCLUSION: The results of this pilot study show that cancers as small as 5 mm can be quantitatively imaged. In addition, preliminary data from the scattering images suggest that benign and malignant tumors can be noninvasively differentiated with optical imaging.

Adenocarcinoma↗