Nodular lymphocyte Hodgkin lymphoma (NLPHL) is a rare disease for which the optimal therapy is unknown. We hypothesized that rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) could decrease rates of relapse and transformation. We retrospectively reviewed patients with NLPHL diagnosed between 1995 and 2015 confirmed by central pathologic review. Fifty-nine had sufficient treatment and follow-up data for analysis. We described progression-free survival (PFS), overall survival (OS), and histologic transformation according to treatment strategy and explored prognostic factors for PFS and OS. The median age at diagnosis was 41 years; 75% were male, and 61% had a typical growth pattern. Twenty-seven patients were treated with R-CHOP with an overall response rate of 100% (complete responses 89%). The median follow-up was 6.7 years, and the estimated 5- and 10-year PFS rates for patients treated with R-CHOP were 88.5% (95% confidence interval [CI], 68.4% to 96.1%) and 59.3 (95% CI, 25.3% to 89.1%), respectively. Excluding patients with histologic transformation at diagnosis, the 5-year cumulative incidence of histologic transformation was 2% (95% CI, 87% to 100%). No patient treated with R-CHOP experienced transformation. A high-risk score from the German Hodgkin Study Group was adversely prognostic for OS ( = .036), whereas male sex and splenic involvement were adversely prognostic for PFS ( = .006 and .002, respectively) but not OS. Our data support a potential role for R-CHOP in patients with NLPHL. Larger prospective trials are needed to define the optimal chemotherapy regimen.
Mammography is the only technique currently used for detecting microcalcification (MC) clusters, an early indicator of breast cancer. However, mammographic images superimpose a three-dimensional compressed breast image onto two-dimensional projection views, resulting in overlapped anatomical breast structures that may obscure the detection and visualization of MCs. One possible solution to this problem is the use of cone beam computed tomography (CBCT) with a flat-panel (FP) digital detector. Although feasibility studies of CBCT techniques for breast imaging have yielded promising results, they have not shown how radiation dose and x-ray tube voltage affect the accuracy with which MCs are detected by CBCT experimentally. We therefore conducted a phantom study using a FP-based CBCT system with various mean glandular doses and kVp values. An experimental CBCT scanner was constructed with a data acquisition rate of 7.5 frames/s. 10.5 and 14.5 cm diameter breast phantoms made of gelatin were used to simulate uncompressed breasts consisting of 100% glandular tissue. Eight different MC sizes of calcium carbonate grains, ranging from 180-200 microm to 355-425 microm, were used to simulate MCs. MCs of the same size were arranged to form a 5 x 5 MC cluster and embedded in the breast phantoms. These MC clusters were positioned at 2.8 cm away from the center of the breast phantoms. The phantoms were imaged at 60, 80, and 100 kVp. With a single scan (360 degrees), 300 projection images were acquired with 0.5 x, 1x, and 2x mean glandular dose limit for 10.5 cm phantom and with 1x, 2x, and 4x for 14.5 cm phantom. A Feldkamp algorithm with a pure ramp filter was used for image reconstruction. The normalized noise level was calculated for each x-ray tube voltage and dose level. The image quality of the CBCT images was evaluated by counting the number of visible MCs for each MC cluster for various conditions. The average percentage of the visible MCs was computed and plotted as a function of the MGD, the kVp, and the average MC size. The results showed that the MC visibility increased with the MGD significantly but decreased with the breast size. The results also showed that the x-ray tube voltage affects the detection of MCs under different circumstances. With a 50% threshold, the minimum detectable MC sizes for the 10.5 cm phantom were 348(+/-2), 288(+/-7), 257(+/-2) microm at 3, 6, and 12 mGy, respectively. Those for the 14.5 cm phantom were 355 (+/-1), 307 (+/-7), 275 (+/-5) microm at 6, 12, and 24 mGy, respectively. With a 75% threshold, the minimum detectable MC sizes for the 10.5 cm phantom were 367 (+/-1), 316 (+/-7), 265 (+/-3) microm at 3, 6, and 12 mGy, respectively. Those for the 14.5 cm phantom were 377 (+/-3), 334 (+/-5), 300 (+/-2) microm at 6, 12, and 24 mGy, respectively.
In cone beam breast computed tomography (CT), scattered radiation leads to nonuniform biasing of CT numbers known as a cupping artifact. Besides being visual distractions, cupping artifacts appear as background nonuniformities, which impair efficient gray scale windowing and pose a problem in threshold based volume visualization/segmentation. To overcome this problem, we have developed a background nonuniformity correction method specifically designed for cone beam breast CT. With this technique, the cupping artifact is modeled as an additive background signal profile in the reconstructed breast images. Due to the largely circularly symmetric shape of a typical breast, the additive background signal profile was also assumed to be circularly symmetric. The radial variation of the background signals was estimated by measuring the spatial variation of adipose tissue signals in front view breast images. To extract adipose tissue signals in an automated manner, a signal sampling scheme in polar coordinates and a background trend fitting algorithm were implemented. The background fits compared with targeted adipose tissue signal value (constant throughout the breast volume) to get an additive correction value for each tissue voxel. To test the accuracy, we applied the technique to cone beam CT images of mastectomy specimens. After correction, the images demonstrated significantly improved signal uniformity in both front and side view slices. The reduction of both intraslice and interslice variations in adipose tissue CT numbers supported our observations.
OBJECTIVE-The purpose of this study was to investigate the feasibility of diagnostic breast imaging using a flat-panel detector-based cone-beam CT system. CONCLUSION-Imaging of 12 mastectomy specimens was performed at 50-80 kVp with a voxel size of 145 or 290 μm. Our study shows that cone-beam breast CT images have exceptional tissue contrast and can potentially reduce examination time with comparable radiation dose.Keywords breast neoplasm; CT radiography; mastectomy; radiation dose; specimen radiography Mammography is an important tool for the screening, diagnosis, and management of breast cancers. The effectiveness of mammography is compromised by fundamental problems including radiation scatter, noise, and the over-lapping of cancers with breast anatomy. Tomosynthesis may partially overcome this limitation, but its image quality suffers from crude depth resolution and associated artifacts [1]. Cone-beam CT, on the other hand, can provide true 3D breast images with isotropic resolution (145 μm or smaller) and radiation dose comparable to two-view mammography [2]. Conventional fan-beam CT applied to breast cancer imaging in the 1970s suffered from limitations including high patient dose, low spatial resolution, long scanning time, large slice thickness, and cardiac and respiratory motion [3,4]. The advantages of cone-beam CT include a flatpanel digital detector, true 3D images with isotropic resolution, reduced motion artifacts, breast-only exposure to radiation, greater efficiency in use of the X-ray beam, no overlapping structures in the breast, and high contrast resolution. We constructed a flat-panel detector-based cone-beam CT system to investigate the feasibility for dedicated breast imaging [5]. Materials and MethodsThe experimental system consists of a general radiography tube pointing at a 30 × 40 cm amorphous silicon (a-Si/CsI) flat-panel digital detector (Paxscan 4030CB, Varian Medical Systems). A motor-driven rotation stage is used to position and rotate the specimen to simulate dedicated breast CT in which the patient would lie on a table in the prone position with one breast drawn downward through an opening to allow the X-ray tube and detector to rotate around and scan the breast beneath the table (Fig. 1).A total of 12 mastectomy specimens were acquired fresh from the pathology laboratory in our institution with institutional review board approval. Each specimen was placed in a receptacle formulated from an inverted soda bottle, and the holder was placed on the rotation stage. Scanning was performed at 50-80 kVp with reconstructed voxel size of 145 or 290 μm. The exposures in air at the isocenter of the cone-beam CT system were measured with a pencil-probe ion chamber, resulting in calculated dose levels equivalent to 6-24 mGy for the breast, which correspond to 1-4 times the mean glandular dose limits for two-view mammograms of a 5-cm-thick compressed breast. ResultsThe mean scanning time was 12 seconds for low-resolution (binning) mode, which was adequate for visualizing tissue struc...
Amorphous silicon/cesium iodide (a-Si:H/CsI:Tl) flat-panel (FP)-based full-field digital mammography systems have recently become commercially available for clinical use. Some investigations on physical properties and imaging characteristics of these types of detectors have been conducted and reported. In this perception study, a phantom containing simulated microcalcifications (microCs) of various sizes was imaged with four detector systems: a FP system, a small field-of-view charge coupled device (CCD) system, a high resolution computed radiography (CR) system, and a conventional mammography screen/film (SF) system. The images were reviewed by mammographers as well as nonradiologist participants. Scores reflecting confidence ratings were given and recorded for each detection task. The results were used to determine the average confidence-rating scores for the four imaging systems. Receiver operating characteristics (ROC) analysis was also performed to evaluate and compare the overall detection accuracy for the four detector systems. For calcifications of 125-140 microm in size, the FP system was found to have the best performance with the highest confidence-rating scores and the greatest detection accuracy (Az = 0.9) in the ROC analysis. The SF system was ranked second while the CCD system outperformed the CR system. The p values obtained by applying a Student t-test to the results of the ROC analysis indicate that the differences between any two systems are statistically significant (p<0.005). Differences in microC detectability for the large (150-160 microm) and small (112-125 microm) size microC groups showed a wider range of p values (not all p values are smaller than 0.005, ranging from 0.6 to <0.001) compared to the p values obtained for the medium (125-140 microm) size microC group. Using the p values to assess the statistical significance, the use of the average confidence-rating scores was not as significant as the use of the ROC analysis p value for p value.
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