A comparison study of size-specific dose estimate calculation methods.

BACKGROUND: The size-specific dose estimate (SSDE) has emerged as an improved metric for use by medical physicists and radiologists for estimating individual patient dose. Several methods of calculating SSDE have been described, ranging from patient thickness or attenuation-based (automated and manual) measurements to weight-based techniques. OBJECTIVE: To compare the accuracy of thickness vs. weight measurement of body size to allow for the calculation of the size-specific dose estimate (SSDE) in pediatric body CT. MATERIALS AND METHODS: We retrospectively identified 109 pediatric body CT examinations for SSDE calculation. We examined two automated methods measuring a series of level-specific diameters of the patient's body: method A used the effective diameter and method B used the water-equivalent diameter. Two manual methods measured patient diameter at two predetermined levels: the superior endplate of L2, where body width is typically most thin, and the superior femoral head or iliac crest (for scans that did not include the pelvis), where body width is typically most thick; method C averaged lateral measurements at these two levels from the CT projection scan, and method D averaged lateral and anteroposterior measurements at the same two levels from the axial CT images. Finally, we used body weight to characterize patient size, method E, and compared this with the various other measurement methods. Methods were compared across the entire population as well as by subgroup based on body width. RESULTS: Concordance correlation (ρc) between each of the SSDE calculation methods (methods A-E) was greater than 0.92 across the entire population, although the range was wider when analyzed by subgroup (0.42-0.99). When we compared each SSDE measurement method with CTDIvol, there was poor correlation, ρc<0.77, with percentage differences between 20.8% and 51.0%. CONCLUSION: Automated computer algorithms are accurate and efficient in the calculation of SSDE. Manual methods based on patient thickness provide acceptable dose estimates for pediatric patients <30 cm in body width. Body weight provides a quick and practical method to identify conversion factors that can be used to estimate SSDE with reasonable accuracy in pediatric patients with body width ≥20 cm.

Efficiency of combined blocking of aerobic and glycolytic metabolism pathways in treatment of N1-S1 hepatocellular carcinoma in a rat model.

BACKGROUND/AIM: The aim of this study was to determine whether the addition of bumetanide (BU), a glycolytic metabolism pathway inhibitor, to arterial embolization improves tumor necrosis of N1-S1 hepatocellular carcinoma in a rat model. MATERIALS AND METHODS: N1-S1 tumors were surgically implanted in the liver of 14 Sprague-Dawley rats. The rats were divided into three groups: In control group (n = 5), 1 ml of normal saline was injected intra-arterially. The tumor in the transarterial embolization group (TAE, n = 4) was embolized using 10 mg of 50-150 µ polyvinyl alcohol (PVA) particles and embolization plus BU group (TAE + BU, n = 5) were embolized with 10 mg of PVA plus 0.04 mg/kg of BU. Tumor volume was measured using two-dimensional ultrasound before intervention and twice a week afterward. Relative tumor volume after the intervention was calculated as the percentage of preinterventional tumor volume. After 4 weeks of observation, the rats were sacrificed for histopathological evaluation. RESULTS: No statistically significant difference was detected in the preintervention tumor sizes between the three groups (P > 0.05). In the control group, the relative tumor volume increased to 142.5% larger than baseline measurements. In the TAE group, the tumor volume decreased by 18.2 ± 12.2%. The tumor volume in the TAE + BU group decrease by 90.4 ± 10.2%, which was 72.2% more than in TAE only group (P < 0.0001). Histopathological evaluation demonstrated no residual tumor in the TAE + BU group. CONCLUSION: Tumor necrosis significantly increased in N1-S1 tumor that received BU at the time of TAE when compared to TAE alone.

Is Ultrasound Fusion a Reasonable Replacement for Computed Tomography in Guiding Abdominal Interventions?

OBJECTIVES: To compare the diagnostic yield, complication rate, and procedure length of ultrasound fusion-guided liver biopsy to the diagnostic yield, complication rate, and procedure length of computed tomography (CT)-guided liver biopsy; to measure the average ionizing radiation dose that patients are exposed to during a typical CT-guided liver biopsy procedure; and to present relevant and interesting cases of ultrasound fusion-guided abdominal interventions to describe the efficacious use of the technology. METHODS: A retrospective analysis of 63 patients who had image-guided liver biopsies performed at our institution was completed. Patient records were divided into 2 groups according to the type of image guidance used during the procedure (ultrasound fusion versus CT), and data were compared by the χ(2) test, Student t test, and Mann-Whitney U test. RESULTS: The diagnostic yields and complication rates were not statistically significantly different between the modalities. The average procedure durations were significantly different: ultrasound fusion-guided biopsy, 31.63 minutes; compared to CT-guided biopsy, 61.67 minutes (P = .003). CONCLUSIONS: Diagnostic yields and complication rates were comparable for ultrasound fusion and CT. However, the average procedure duration for an ultrasound fusion-guided liver biopsy was approximately half that of CT-guided liver biopsy, likely increasing both cost-effectiveness and patient satisfaction.

Successful Dose Reduction Using Reduced Tube Voltage With Hybrid Iterative Reconstruction in Pediatric Abdominal CT.

OBJECTIVE: The purpose of this article is to assess radiation dose reduction, image quality, and diagnostic confidence using low tube voltage in combination with hybrid iterative reconstruction in contrast-enhanced pediatric abdominal CT. MATERIALS AND METHODS: CT examinations of 133 patients (median age, 10 years) were performed at sequentially reduced doses. The first group (group 1) was scanned using dimension-based protocols at 120 kV for all patient sizes. The optimized group (group 5) was scanned at 80 kV for less than 18 cm in the lateral dimension and 100 kV in the 19-30 cm lateral dimension. CT examinations reconstructed with filtered back projection (FBP) and four levels of hybrid iterative reconstruction were reviewed by four blinded readers for subjective image quality and diagnostic confidence. Objective noise, volume CT dose index (CTDIvol), and size-specific dose estimate (SSDE) were recorded. Data were analyzed using t tests, one and two-way ANOVA, and the intraclass correlation coefficient. RESULTS: Compared with group 1, the radiation dose was reduced for group 5 by 63% measured by SSDE (4.69 vs 10.00 mGy; p < 0.001). Subjective image noise was increased for FBP images (p < 0.001) but not was statistically significantly different for all levels of hybrid iterative reconstruction; artifacts were reduced and visibility of small structures was improved (both p < 0.001). Diagnostic confidence was improved for solid organ injury and metastatic disease (both p < 0.001) and was not statistically significantly different for appendicitis (p = 0.306). CONCLUSION: Use of hybrid iterative reconstruction with low-tube-voltage protocols enables substantial radiation dose reduction for pediatric abdominal CT with equivalent to improved subjective image quality and diagnostic confidence.

The cost of doing business in academic radiology departments.

This study identifies the major sources of overhead fees/costs and subsidies in academic radiology departments (ARDs) in the US and determines the differences between them based on geographic location or the size of their affiliated hospital. ARDs in the Northeast had the highest level of financial support from their affiliated hospitals when compared to those in the South/Southwest; however, a greater number of Midwest ARDs receive high levels of funding for teaching from their medical schools when compared to the northeast. Significantly fewer ARDs affiliated with hospitals of less than 200 beds receive subsidies for their activities when compared to those affiliated with larger hospitals. Differences in levels of overhead costs/ subsidies available to ARDs are associated with either geographic location or the size of the affiliated hospital. The reasons for these differences may be related to a variety of legal, contractual, or fiscal factors. Investigation of existing geographic and affiliate size fiscal differences and their causes by ARDs may be of benefit.

Impact of Patient Protection and Affordable Care Act on academic radiology departments' clinical, research, and education missions.

The Patient Protection and Affordable Care Act (ACA) generated significant media attention since its inception. When the law was approved in 2010, the U.S. health care system began facing multiple changes to adapt and to incorporate measures to meet the new requirements. These mandatory changes will be challenging for academic radiology departments (ARDs) since they will need to promote a shift from a volume-focused to a value-focused practice. This will affect all components of the mission of ARDs, including clinical practice, education, and research. A unique key element to success in this transition is to focus on both quality and safety, thus improving the value of radiology in the post-ACA era. Given the changes ARDs will face during the implementation of ACA, suggestions are provided on how to adapt ARDs to this new environment.

Utilization of dashboard technology in academic radiology departments: results of a national survey.

PURPOSE: The aim of this study was to identify the most widely used financial, productivity, and accessibility metrics used by academic radiology departments (ARDs) in a dashboard format via a national survey. The results provide a guide to the selection of preferred or commonly used indicators to facilitate dashboard implementation and use. METHODS: The study met the criteria for an exemption from institutional review board approval. A cross-sectional survey was conducted using a survey approved by the Society of Chairs of Academic Radiology Departments and sent to its members. The survey was designed to evaluate the adoption, access, and composition of dashboard technology in ARDs, particularly those related to measures of productivity and financial performance. RESULTS: The overall response rate was 42% (56 of 131 members). Sixty-two percent of responding ARDs currently use some form of dashboard technology, but 50% have used this technology for ≤2 years. Sixty-five percent of all ARDs use their dashboard information on a monthly basis. The two dashboard financial indicators most frequently used by ARDs are revenue and actual expenses. Similarly, the two productivity indicators used most widely are total examination volume and examination volume per modality. The two most important access indicators used are report turnaround time and backlog per unit time. CONCLUSIONS: Currently, fewer than two-thirds of the responding ARDs use dashboard technology, and one-half have used the technology for ≤2 years. Although some fiscal and productivity indices are more frequently used, there are a diverse number of factors used to measure productivity, finance, access, and other operational parameters in ARD dashboards. Thus, the information provided by each institutional dashboard may be significantly different from that in other ARDs.

A comparison of computer-aided detection (CAD) effectiveness in pulmonary nodule identification using different methods of bone suppression in chest radiographs.

This study aimed to compare the diagnostic effectiveness of computer-aided detection (CAD) software (OnGuard™ 5.2) in combination with hardware-based bone suppression (dual-energy subtraction radiography (DESR)), software-based bone suppression (SoftView™, version 2.4), and standard posteroanterior images with no bone suppression. A retrospective pilot study compared the diagnostic performance of two commercially available methods of bone suppression when used with commercially available CAD software. Chest images from 27 patients with computed tomography (CT) and pathology-proven malignant pulmonary nodules (8-34 mm) and 25 CT-negative patient controls were used for analysis. The Friedman, McNemar, and chi-square tests were used to compare diagnostic performance and the kappa statistic was used to evaluate method agreement. The average number of regions of interest and false-positives per image identified by CAD were not found to be significantly different regardless of the bone suppression methods evaluated. Similarly, the sensitivity, specificity, and test efficiency were not found to be significantly different. Agreement between the methods was between poor and excellent. The accuracy of CAD (OnGuard™, version 5.2) is not statistically different with either DESR or SoftView™ (version 2.4) bone suppression technology in digital chest images for pulmonary nodule identification. Low values for sensitivity (<80 %) and specificity (<50 %) may limit their utility for clinical radiology.

Neglecting to screen women between the ages of 40 and 49 years with mammography: what is the impact on breast cancer diagnosis?

OBJECTIVE: The purpose of this study was to compare breast cancer stage at diagnosis in two groups of women between 40 and 49 years old: women undergoing screening mammography and women with a symptom needing diagnostic workup. This comparison is indicative of the impact of forgoing screening in this age group, as recommended by the United States Preventive Services Task Force. MATERIALS AND METHODS: A retrospective chart review was used to collect the results of imaging-guided core needle biopsies performed in women between the ages of 40 and 49 years from January 1, 2008, to December 31, 2009. In patients diagnosed with breast cancer or a high-risk lesion, the reason for presentation, pathology, tumor size, stage, and receptor characteristics were recorded. The chi-square test was used for statistical analysis. RESULTS: Of 108 primary breast cancers, 71 were detected in the screened group and 37 in the unscreened group. The screened group was significantly more likely to be diagnosed with ductal carcinoma in situ than the unscreened group (22 vs 1, chi-square = 11.6, p = 0.001). Furthermore, screened patients with invasive carcinoma were significantly more likely to be diagnosed at earlier stages (chi-square = 5.02, p = 0.025). The size of invasive breast cancer in the screened group was significantly smaller as well (chi-square = 9.3, p = 0.002). Of the high-risk lesions, atypical ductal hyperplasia (n = 29) and lobular carcinoma in situ (n = 8) were most frequently seen. CONCLUSION: Breast cancer patients undergoing screening mammography were diagnosed at earlier stages with smaller tumors. Screening also allows detection of high-risk lesions, which may prompt chemoprevention and lower subsequent breast cancer risk. We continue to support screening mammography in women between the ages of 40 and 49 years.

Dual energy subtraction digital radiography improves performance of a next generation computer-aided detection program.

PURPOSE: Computer-aided detection (CAD) has shown potential to assist physicians in the detection of lung nodules on chest radiographs, but widespread acceptance has been stymied by high false-positive rates. Few studies have examined the potential for dual energy subtraction (DES) to improve CAD performance. MATERIALS AND METHODS: Institutional review board approval was obtained, the requirement for informed consent was waived because the study was retrospective, and practices conformed to Health Insurance Portability and Accountability Act regulations. The CAD program was applied retrospectively to dual energy posteroanterior (PA) chest radiographs of 36 patients (17 women, 19 men, mean age 69 y) with 48 pathology proven lung nodules. Results were analyzed to determine the stand-alone CAD program false-positive rates, and sensitivity by nodule subtlety and location. Statistical analysis was performed using the chi(2) or Fisher exact tests for independence of sensitivities between standard PA and DES radiography. Differences in the mean false-positives per image (FPPI) between radiographic modalities were determined using the paired Students t test, and bootstrap confidence intervals were obtained to confirm results. RESULTS: The sensitivity of the CAD program with the standard PA was 46% (22 of 48 nodules) compared with 67% (32 of 48 nodules) using the DES soft tissue or bone-subtracted view (P=0.064). The average number of FPPI identified by CAD was significantly lower using DES (FPPI(soft tissue) = 1.64) when compared with the standard PA chest radiograph (FPPI(PA) = 2.39) (P<0.01). CONCLUSIONS: DES has the potential to improve stand-alone CAD performance by both increasing sensitivity for certain subtle lung cancer lesions and decreasing overall CAD false-positive rates.