New compression paddle for wire localization in mammography.

RATIONALE AND OBJECTIVES: Current wire localization compression paddles provide a limited access window with no compression in this window. We describe a new compression paddle that addresses these issues and report on preliminary patient testing. MATERIALS AND METHODS: Four mechanical engineering students collaborated with a medical physicist, a radiographer, and two radiologists. Several concept designs were developed, one of which used a mesh surface. This went on to prototype development. After phantom testing, internal review board approval, US Food and Drug Administration waiver for nonsignificant risk device, and Medicare Part A exemption were obtained, the device was used in 10 patients going to wire localization for medical indications. Informed consent was obtained and a range of breast size was included. Wires were positioned from superior, lateral, and medial approach. RESULTS: A total of 10 wires were successfully positioned in nine patients. The one technical failure was due to inadequate access to the axillary region because of the single prototype size. The grid system provided accurate localization of suspicious findings. The mesh was not visible in digital mammograms so there was no interference. CONCLUSION: The new paddle improves on currently available models. Advantages included lack of visual (on imaging) and technical interference from the compression mesh, and compression of the active window allowed localization of subtle findings. The large active area facilitated multiple wire placements within a single window. All localizations were easily performed on the initial image because of the large active window, obviating the need for acquisition of additional images and the associated additional radiation.

Multi-modality CADx: ROC study of the effect on radiologists' accuracy in characterizing breast masses on mammograms and 3D ultrasound images.

RATIONALE AND OBJECTIVES: To investigate the effect of a computer-aided diagnosis (CADx) system on radiologists' performance in discriminating malignant and benign masses on mammograms and three-dimensional (3D) ultrasound (US) images. MATERIALS AND METHODS: Our dataset contained mammograms and 3D US volumes from 67 women (median age, 51; range: 27-86) with 67 biopsy-proven breast masses (32 benign and 35 malignant). A CADx system was designed to automatically delineate the mass boundaries on mammograms and the US volumes, extract features, and merge the extracted features into a multi-modality malignancy score. Ten experienced readers (subspecialty academic breast imaging radiologists) first viewed the mammograms alone, and provided likelihood of malignancy (LM) ratings and Breast Imaging and Reporting System assessments. Subsequently, the reader viewed the US images with the mammograms, and provided LM and action category ratings. Finally, the CADx score was shown and the reader had the opportunity to revise the ratings. The LM ratings were analyzed using receiver-operating characteristic (ROC) methodology, and the action category ratings were used to determine the sensitivity and specificity of cancer diagnosis. RESULTS: Without CADx, readers' average area under the ROC curve, A(z), was 0.93 (range, 0.86-0.96) for combined assessment of the mass on both the US volume and mammograms. With CADx, their average A(z) increased to 0.95 (range, 0.91-0.98), which was borderline significant (P = .05). The average sensitivity of the readers increased from 98% to 99% with CADx, while the average specificity increased from 27% to 29%. The change in sensitivity with CADx did not achieve statistical significance for the individual radiologists, and the change in specificity was statistically significant for one of the radiologists. CONCLUSIONS: A well-trained CADx system that combines features extracted from mammograms and US images may have the potential to improve radiologists' performance in distinguishing malignant from benign breast masses and making decisions about biopsies.

Academic radiology and the emergency department: does it need changing?

RATIONAL AND OBJECTIVES: The increasing importance of imaging for both diagnosis and management in patient care has resulted in a demand for radiology services 7 days a week, 24 hours a day, especially in the emergency department (ED). We hypothesized the resident preliminary reports were better than generalist radiology interpretations, although inferior to subspecialty interpretations. MATERIALS AND METHODS: Total radiology volume through our Level I pediatric and adult academic trauma ED was obtained from the radiology information system. We conducted a literature search for error and discordant rates between radiologists of varying experience. For a 2-week prospective period, all preliminary reports generated by the residents and final interpretations were collected. Significant changes in the report were tabulated. RESULTS: The ED requested 72,886 imaging studies in 2004 (16% of the total radiology department volume). In a 2-week period, 12 of 1929 (0.6%) preliminary reports by residents were discordant to the final subspecialty dictation. In the 15 peer-reviewed publications documenting error rates in radiology, the error rate between American Board of Radiology (ABR)-certified radiologists is greater than that between residents and subspecialists in the literature and in our study. However, the perceived error rate by clinicians outside radiology is significantly higher. CONCLUSION: Sixteen percent of the volume of imaging studies comes through the ED. The residents handle off-hours cases with a radiology-detected error rate below the error rate between ABR-certified radiologists. To decrease the perceived clinician-identified error rate, we need to change how academic radiology handles ED cases.

Contrast-enhanced CT accurately detects hemorrhage in torso trauma: direct comparison with angiography.

OBJECTIVE: To assess the ability of contrast enhanced computed tomography (CECT) to detect active hemorrhage and other vascular injuries in chest, abdominal, and pelvic trauma patients, using angiographic findings and need for intervention as paired gold standards. METHODS: We obtained approval from the Institutional review board for a retrospective search of the radiology information system: seeking trauma patients undergoing angiography within 24 hours of CECT for chest, abdominal, or pelvic injuries. CECT protocol was standard trauma CT, not specialized for CT angiography. Angiographic techniques varied with indication. Clinical and imaging reports and selected radiologic studies were reviewed, but the original dictated report was the interpretive standard. We used Fisher's exact test for statistical analysis. RESULTS: During the 30-month study period, 466 patients underwent emergent interventional radiologic procedures. Of those, 418 were excluded for nontrauma indications or neuroangiographic procedures. Fourty-eight patients (33 male, 15 female, average age 43.4) thus constituted the study population in whom we evaluated 63 traumatic injuries. CT findings had statistically significant associations (p < 0.0001) with both angiographic evidence of active hemorrhage and the need for intervention, which were tabulated separately. CT had 94.1% sensitivity and 97.6% negative predictive value (NPV) for detection of active hemorrhage, and 92.6% sensitivity and 91.2% NPV for predicting need for surgical or endovascular intervention. CONCLUSIONS: CECT findings correlate strongly with angiographic findings, though sensitivity remains imperfect. However, when CT is used in the context of other clinical features, particularly hemodynamic instability, it may enable clinicians to reserve emergent angiography for those patients in whom emergent intervention is planned.

Costs of achieving high patient compliance after recall from screening mammography.

OBJECTIVE: The purpose of our study was to document the hidden costs in achieving high recall patient compliance from an off-site screening mammography program. MATERIALS AND METHODS: This study was approved by our institutional review board. At our institution, no patient was placed in final BI-RADS assessment category 3, 4, or 5 without a diagnostic study. Each incomplete study, in addition to the formal report, was flagged on the day sheet, letters were sent to the referring physician and patient, and an incomplete computer code was added. Working from the day sheets, a clerk contacted the patient by telephone within 2 working days to schedule the diagnostic study. Diagnostic slots were purposely left open to accommodate these cases. An ongoing computer tickler file of incomplete codes provided a further check. A time study of clerical performance with recalled patients was measured prospectively for 100 consecutive cases. RESULTS: For the years 2002-2004, 4,025 (13%) of 30,286 screening patients were recalled for diagnostic mammography. After an average of 2.2 telephone calls per patient, (3.64 minutes of clerical time), 3,977 of 4,005 patients returned for a diagnostic study. Forty-eight of 4,025 initially noncompliant patients received an average of six telephone calls (4.7 minutes) and a registered letter. One of the 28 initially noncompliant patients went on to biopsy that revealed a breast cancer. Patient compliance was 4,005 (99.5%) of 4,025. The additional cost for this program was $4,724 divided by 30,286 screening patients, or 16 cents per screening patient. CONCLUSION: The radiology department assumed responsibility for contacting patients who needed recall for additional diagnostic imaging. Using strict documentation of the incomplete breast imaging evaluations, computer checks, clerical support, and prompt scheduling, we achieved 99.5% compliance. The additional cost was small, 16 cents per screening patient.

Effects on breast MRI of artifacts caused by metallic tissue marker clips.

OBJECTIVE: The purpose of our study was to investigate MR artifacts related to tissue marker clips used in breast imaging procedures. MATERIALS AND METHODS: Breast phantoms were created using gelatin doped with gadolinium. Four commercially available tissue marker clips were evaluated. Clinical MR evaluation of all phantoms with 1.5-T gradient-recalled echo sequences was performed. Images were evaluated for size and character of the visible artifacts and graphically appreciable fat saturation inhomogeneities. Quantitative measurement of the local inhomogeneity in 3D parts per million maps was obtained as a function of distance from each tissue marker. RESULTS: All tissue marker clips caused signal void artifacts on non-fat-suppressed images that measured 2-6 times the clip diameter. The degree of fat suppression inhomogeneity was minor but clinically appreciable. The local clip-induced field inhomogeneity varied from 0.25 to greater than 4.0 PPM for the four clips. At 0.25 PPM, the zonal diameter of frequency shift varied from 6 mm to 44 mm. CONCLUSION: Artifacts caused by tissue marker clips could limit the sensitivity of MRI for detection and follow-up of breast cancer. The local effects on field inhomogeneity will affect local fat suppression and make spectroscopy data less reliable. These effects, though small, are measurable and vary among the different clips evaluated.

Mammographic density measured with quantitative computer-aided method: comparison with radiologists' estimates and BI-RADS categories.

PURPOSE: To retrospectively compare computer-aided mammographic density estimation (MDEST) with radiologist estimates of percentage density and Breast Imaging Reporting and Data System (BI-RADS) density classification. MATERIALS AND METHODS: Institutional Review Board approval was obtained for this HIPAA-compliant study; patient informed consent requirements were waived. A fully automated MDEST computer program was used to measure breast density on digitized mammograms in 65 women (mean age, 53 years; range, 24-89 years). Pixel gray levels in detected breast borders were analyzed, and dense areas were segmented. Percentage density was calculated by dividing the number of dense pixels by the total number of pixels within the borders. Seven breast radiologists (five trained with MDEST, two not trained) prospectively assigned qualitative BI-RADS density categories and visually estimated percentage density on 260 mammograms. Qualitative BI-RADS assessments were compared with new quantitative BI-RADS standards. The reference standard density for this study was established by allowing the five trained radiologists to manipulate the MDEST gray-level thresholds, which segmented mammograms into dense and nondense areas. Statistical tests performed include Pearson correlation coefficients, Bland-Altman agreement method, kappa statistics, and unpaired t tests. RESULTS: There was a close correlation between the reference standard and radiologist-estimated density (R = 0.90-0.95) and MDEST density (R = 0.89). Untrained radiologists overestimated percentage density by an average of 37%, versus 6% for trained radiologists (P < .001). MDEST showed better agreement with the reference standard (average overestimate, 1%; range, -15% to +18%). MDEST correlated better with percentage density than with qualitative BI-RADS categories. There were large overlaps and ranges of percentage density in qualitative BI-RADS categories 2-4. Qualitative BI-RADS categories correlated poorly with new quantitative BI-RADS categories, and 16 (6%) of 260 views were erroneously classified by MDEST. CONCLUSION: MDEST compared favorably with radiologist estimates of percentage density and is more reproducible than radiologist estimates when qualitative BI-RADS density categories are used. Qualitative and quantitative BI-RADS density assessments differed markedly.

ROC study of the effect of stereoscopic imaging on assessment of breast lesions.

An observer performance study was conducted to evaluate the usefulness of assessing breast lesion characteristics with stereomammography. Stereoscopic image pairs of 158 breast biopsy tissue specimens were acquired with a GE Senographe 2000D full field digital mammography system using a 1.8x magnification geometry. A phantom-shift method equivalent to a stereo shift angle of +/- 3 degrees relative to a central axis perpendicular to the detector was used. For each specimen, two pairs of stereo images were taken at approximately orthogonal orientations. The specimens contained either a mass, microcalcifications, both, or normal tissue. Based on pathological analysis, 39.9% of the specimens were found to contain malignancy. The digital specimen radiographs were displayed on a high resolution MegaScan CRT monitor driven by a DOME stereo display board using in-house developed software. Five MQSA radiologists participated as observers. Each observer read the 316 specimen stereo image pairs in a randomized order. For each case, the observer first read the monoscopic image and entered his/her confidence ratings on the presence of microcalcifications and/or masses, margin status, BI-RADS assessment, and the likelihood of malignancy. The corresponding stereoscopic images were then displayed on the same monitor and were viewed through stereoscopic LCD glasses. The observer was free to change the ratings in every category after stereoscopic reading. The ratings of the observers were analyzed by ROC methodology. For the 5 MQSA radiologists, the average Az value for estimation of the likelihood of malignancy of the lesions improved from 0.70 for monoscopic reading to 0.72 (p=0.04) after stereoscopic reading, and the average Az value for the presence of microcalcifications improved from 0.95 to 0.96 (p=0.02). The Az value for the presence of masses improved from 0.80 to 0.82 after stereoscopic reading, but the difference fell short of statistical significance (p=0.08). The visual assessment of margin clearance was found to have very low correlation with microscopic analysis with or without stereoscopic reading. This study demonstrates the potential of using stereomammography to improve the detection and characterization of mammographic lesions.

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.

Pulmonary involvement in pediatric lymphoma.

BACKGROUND: The prevalence of pulmonary lymphoma in the pediatric age group is not documented in the literature. OBJECTIVE: This study was designed to assess the prevalence of pulmonary parenchymal lymphoma in children with Hodgkin disease (HD), non-Hodgkin lymphoma (NHL) and post-transplant lymphoproliferative disorder (PTLD). MATERIALS AND METHODS: A 10-year retrospective analysis of 161 lymphoma patients (62 girls and 99 boys), mean age of 12.4 years, was performed. The definition of pulmonary lymphoma excluded those with isolated pleural disease and/or mediastinal adenopathy. RESULTS: Eighty-two patients had HD, 65 had NHL, and 14 had PTLD. Overall prevalence of pulmonary parenchymal involvement was 13% (21/161), including 12% of patients with HD, 10% of patients with NHL, and 29% of patients with PTLD. CT findings included: pulmonary nodules (90%) or mass (38%); interstitial (9%) or alveolar (9%) disease; cavitation (9%); and pleural based mass (9%). CONCLUSIONS: Pulmonary parenchymal disease in our pediatric lymphoma population was more prevalent than expected (13%). This is significant for patient management. New pulmonary lesions in patients with known lymphoma should be regarded with suspicion. In the setting of immune suppression, pulmonary lesions treated as infection may actually represent lymphoma. Expeditious biopsy of lesions failing to respond promptly to antibiotic therapy should be considered.

Pediatric renal pelvic fullness: an ultrasonographic dilemma.

PURPOSE: We conducted a prospective study to define normal renal pelvic size in children. MATERIALS AND METHODS: Institutional Review Board approved consent was obtained to perform renal ultrasound during excretory urography (IVP) scheduled for medical management. Mean patient age (17 females, 11 males) was 5.2 years. Renal ultrasound was conducted concurrent with 10-minute IVP. RESULTS: Fifty kidneys were imaged with 51 collecting systems. IVP defined 44 collecting systems as normal. Mean anteroposterior pelvic diameter on sonography for these 44 systems was 3.3 mm. One normal collecting system on IVP had a diameter greater than 10 mm on ultrasound (14 mm). No sonographic caliceal dilatation was seen in any kidney appearing normal on IVP. The 7 dilated systems on IVP had a mean ultrasound diameter of 17.1 mm. Two dilated collecting systems smaller than 10 mm in diameter on sonography had caliceal distention on ultrasound. CONCLUSIONS: Normal renal pelvis threshold diameter was 10 mm in asymptomatic children. We recommend further evaluation in children with caliceal dilatation and/or dilatation of the anteroposterior renal pelvis greater than 10 mm. Using these criteria, no system appearing abnormal on IVP would have been missed.

The effect of screening sonography on the positive rate of enemas for intussusception.

BACKGROUND: The referring physicians at our institution used the enema as a diagnostic test in children with suspected intussusception. OBJECTIVE: To determine the change in rate of positive enema findings performed for suspected intussusception with the intervention of screening ultrasound (US). MATERIALS AND METHODS: Since October 1995, 224 children (mean age 2.2 years) with suspected intussusception were referred for enema examination. In January 2001, US was introduced as a screening test for intussusception. Enemas were performed for all children with positive US findings and were offered for those with negative US findings if clinical suspicion persisted. RESULTS: Before 2001, 184 children underwent enema with intussusception documented in 40 (22%). Since January 2001, 40 children have been seen with suspected intussusception (12/40 positive or 30%). Two directly underwent enema (1/2 positive); 38 children underwent US. In 12 of 38 children, the US finding was positive, and an intussusception was found at enema examination in 11 of 12. In 26 cases, the US finding was negative. Seven of the 26 children with a negative sonogram finding had an enema, which was also negative. Nineteen enemas were canceled. With a screening US, the positive rate for enemas is now 58% (11/19). We know of no case of intussusception missed at US. CONCLUSION: Screening US has decreased unnecessary enemas for clinically suspected intussusception, increasing positive findings from 22% to 58%. This has in turn reduced children's exposure to radiation.

Computed tomographic diagnosis of unsuspected pyelonephritis in children.

OBJECTIVE: To emphasize the utility of computed tomography (CT) in the diagnosis of pyelonephritis in children with complex comorbidities. METHODS: We retrospectively reviewed the CT imaging studies and medical records of 12 patients (8 girls, 4 boys; aged 2-18 years [mean 8.6 yr]) who did not have a classic presentation of pyelonephritis but were diagnosed by CT. All patients had fever at clinical presentation, and pyelonephritis was not suspected in any case. Two children had negative urine cultures before imaging. RESULTS: All 12 patients had wedge-shaped areas of hypoattenuation on CT, 7 bilaterally; 10 had enlargement of an involved kidney; 5 had perinephric fat stranding; and 3 had focal abscesses. CONCLUSIONS: Although classic and uncomplicated pyelonephritis is a clinical diagnosis that does not require imaging, sometimes the presentation may be equivocal and the diagnosis unsuspected. Pyelonephritis is one of several potential sources of fever that can be simultaneously evaluated using CT. Using. CT, the unsuspected diagnosis of pyelonephritis can be made and therapy initiated before the urine culture is positive.

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.