[Show abstract][Hide abstract] ABSTRACT: Purpose:
To compare the Medicare population cost of colorectal cancer (CRC) screening of average risk individuals by CT colonography (CTC) vs. optical colonoscopy (OC).
The authors used Medicare claims data, fee schedules, established protocols, and other sources to estimate CTC and OC per-screen costs, including the costs of OC referrals for a subset of CTC patients. They then modeled and compared the Medicare costs of patients who complied with CTC and OC screening recommendations and tested alternative scenarios.
CTC is 29% less expensive than OC for the Medicare population in the base scenario. Although the CTC cost advantage is increased or reduced under alternative scenarios, it is always positive.
CTC is a cost-effective CRC screening option for the Medicare population and will likely reduce Medicare expenditures for CRC screening.
[Show abstract][Hide abstract] ABSTRACT: Purpose:
Noise index (NI) enables the mAs to be automatically determined to achieve the desired CT
noise level. The scientific foundation behind the use of NI is the linear relationship between noise variance (σ2) and the 1/mAs. This relationship has been severely violated by the use of the highly nonlinear MBIR algorithm, making the traditional NI system no longer valid. This work studied how the quantitative relationship between σ2 and mAs should be modified in MBIR so that a new NI-mAs correspondence can be established.
Medical Physics 06/2015; 42(6):3548. DOI:10.1118/1.4925276 · 2.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The introduction of the highly nonlinear MBIR algorithm to clinical CT systems has made CNR an invalid metric for kV optimization. The purpose of this work was to develop a task-based framework to unify kV and mAs optimization for both FBP- and MBIR-based CT systems.
The kV-mAs optimization was formulated as a constrained minimization problem: to select kV and mAs to minimize dose under the constraint of maintaining the detection performance as clinically prescribed. To experimentally solve this optimization problem, exhaustive measurements of detectability index (d') for a hepatic lesion detection task were performed at 15 different mA levels and 4 kV levels using an anthropomorphic phantom. The measured d' values were used to generate an iso-detectability map; similarly, dose levels recorded at different kV-mAs combinations were used to generate an iso-dose map. The iso-detectability map was overlaid on top of the iso-dose map so that for a prescribed detectability level d', the optimal kV-mA can be determined from the crossing between the d' contour and the dose contour that corresponds to the minimum dose.
Taking d'=16 as an example: the kV-mAs combinations on the measured iso-d' line of MBIR are 80-150 (3.8), 100-140 (6.6), 120-150 (11.3), and 140-160 (17.2), where values in the parentheses are measured dose values. As a Result, the optimal kV was 80 and optimal mA was 150. In comparison, the optimal kV and mA for FBP were 100 and 500, which corresponded to a dose level of 24 mGy. Results of in vivo animal experiments were consistent with the phantom results.
A new method to optimize kV and mAs selection has been developed. This method is applicable to both linear and nonlinear CT systems such as those using MBIR. Additional dose savings can be achieved by combining MBIR with this method. This work was partially supported by an NIH grant R01CA169331 and GE Healthcare. K. Li, D. Gomez-Cardona, M. G. Lubner: Nothing to disclose. P. J. Pickhardt: Co-founder, VirtuoCTC, LLC Stockholder, Cellectar Biosciences, Inc. G.-H. Chen: Research funded, GE Healthcare; Research funded, Siemens AX.
Medical Physics 06/2015; 42(6):3620. DOI:10.1118/1.4925689 · 2.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: IntroductionSince its introduction 20 years ago, CT colonography (CTC), also referred to as virtual colonoscopy, has evolved from an experimental research tool with relatively limited clinical applications to a validated colorectal examination [1-3]. For certain diagnostic indications, such as following an incomplete optical colonoscopy (OC), CTC is now well established throughout most of the developed world [4-8]. CTC for the purpose of asymptomatic screening, however, is currently performed in only a handful of experienced centers. The need for additional effective screening options for colorectal cancer (CRC) is clear since this preventable condition remains the second leading cause of cancer death in the USA . Although CTC is now poised for broader implementation as a frontline screening tool, a number of hurdles persist—none of which is likely insurmountable or even related to its clinical performance profile [10, 11]. This update will review the relative advantages and disadva ...
[Show abstract][Hide abstract] ABSTRACT: Colorectal cancer (CRC) is the second most common cancer and second most common cause of cancer-related deaths in Europe. The introduction of CRC screening programmes using stool tests and flexible sigmoidoscopy, have been shown to reduce CRC-related mortality substantially. In several European countries, population-based CRC screening programmes are ongoing or being rolled out. Stool tests like faecal occult blood testing are non-invasive and simple to perform, but are primarily designed to detect early invasive cancer. More invasive tests like colonoscopy and CT colonography (CTC) aim at accurately detecting both CRC and cancer precursors, thus providing for cancer prevention. This review focuses on the accuracy, acceptance and safety of CTC as a CRC screening technique and on the current position of CTC in organised population screening. Based on the detection characteristics and acceptability of CTC screening, it might be a viable screening test. The potential disadvantage of radiation exposure is probably overemphasised, especially with newer technology. At this time-point, it is not entirely clear whether the detection of extracolonic findings at CTC is of net benefit and is cost effective, but with responsible handling, this may be the case. Future efforts will seek to further improve the technique, refine appropriate diagnostic algorithms and study cost-effectiveness.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Gut 12/2014; 64(2). DOI:10.1136/gutjnl-2014-308696 · 14.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose:
To retrospectively identify morphologic findings at computed tomographic (CT) colonography that are the most reliable in the differentiation of masslike chronic diverticular disease from sigmoid carcinoma in a large patient cohort.
Materials and methods:
This study was approved by the institutional review boards. The need for signed consent was waived for this retrospective study. The cohort consisted of 212 patients (mean age, 68 years; 113 women, 99 men) with focal masslike findings in the sigmoid colon at CT colonography, representing chronic diverticular disease (n = 97) or sigmoid carcinoma (n = 115). CT colonography studies were scored according to presence or absence of potential discriminators by a panel of four readers in consensus. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated, and multivariate analysis was performed.
Absence of diverticula in the affected segment showed high NPV and PPV (0.95 and 0.93, respectively). Also, shoulder phenomenon showed a high NPV (0.92) and PPV (0.75). Segment length of 10 cm or less (NPV, 0.85; PPV, 0.61) and destroyed mucosal folds (NPV, 1.00; PPV, 0.62) had a high NPV but a low PPV. Although segments affected by carcinoma often showed straightened and eccentric growth patterns, no thick fascia sign, and more and larger local-regional lymph nodes (all P < .05), NPV was insufficient for discrimination (NPV ≤ 0.66). Combination of absence of diverticula and presence of shouldering showed a high diagnostic certainty (93%).
Carcinoma is best differentiated from masslike diverticular disease by the absence of diverticula in the affected segment and the presence of shoulder phenomenon.
[Show abstract][Hide abstract] ABSTRACT: Purpose of review:
The aim of this review is to provide an update on important recent advances in radiologic colorectal imaging, with emphasis on detection, staging, and surveillance of colorectal neoplasia.
Colorectal imaging advances with magnetic resonance (MR), computed tomography colonography (CTC), and positron emission tomography (PET) over the past year or so have been substantial. Progress in MRI for rectal cancer was most notable in terms of assessment of response to neoadjuvant therapy. Continued maturation and clinical validation of CTC was observed for the evaluation of advanced neoplasia, among other areas. Multimodality approaches to colorectal imaging that incorporate functional PET data have also made impressive strides forward.
Recent advances in cross-sectional and functional radiologic imaging of the colorectum will positively impact the clinical capabilities for noninvasive evaluation of colorectal neoplasia.
Current Opinion in Gastroenterology 11/2014; 31(1). DOI:10.1097/MOG.0000000000000141 · 4.29 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aim:
To perform an objective, intra-individual comparison of residual colonic fluid volume and attenuation associated with the current front-line laxative magnesium citrate (MgC) versus the former front-line laxative sodium phosphate (NaP) at CT colonography (CTC).
Materials and methods:
This retrospective Health Insurance and Portability and Accountability Act-compliant study had institutional review board approval; informed consent was waived. The study cohort included 250 asymptomatic adults (mean age at index 56.1 years; 124 male/126 female) who underwent CTC screening twice over a 5 year interval. Colon catharsis at initial and follow-up screening employed single-dose NaP and double-dose MgC, respectively, allowing for intra-patient comparison. Automated volumetric analysis of residual colonic fluid volume and attenuation was performed on all 500 CTC studies. Colonic fluid volume <200 ml and mean attenuation between 300-900 HU were considered optimal. Paired t-test and McNemar's test were used to compare differences.
Residual fluid volumes <200 ml were recorded in 192 examinations (76.8%) following MgC and in 204 examinations (81.6%) following NaP (p = 0.23). The mean total residual fluid volume was 155 ± 114 ml for MgC and 143 ± 100 ml for NaP (p = 0.01). The attenuation range of 300-900 HU was significantly more frequent for MgC (n = 220, 88%) than for NaP (n = 127, 50.8%; p < 0.001). Mean fluid attenuation was significantly lower for MgC (700 ± 165 HU) than for NaP (878 ± 155 HU; p < 0.001). Concomitant presence of both optimal fluid volume and attenuation was significantly more frequent for MgC 65.2% than for NaP (38%; p < 0.001).
Objective intra-individual comparison using automated volumetric analysis suggests that the replacement of NaP by MgC as the front-line laxative for CTC has not compromised overall examination quality.
[Show abstract][Hide abstract] ABSTRACT: Although the overall prevalence of peptic ulcer disease (PUD) and related hospitalizations are decreasing, the initial presentation of complicated PUD on CT remains common. It, therefore, remains critical for radiologists to recognize the findings of PUD at CT for initial diagnosis. While the CT findings of complicated PUD have been previously described in the literature, the CT findings of uncomplicated PUD have not been well documented. Furthermore, although CT is certainly not the diagnostic evaluation of choice for patients with suspected uncomplicated PUD, many patients with PUD will nonetheless present to the emergency department with unexplained abdominal pain and undergo MDCT evaluation as the initial diagnostic test. Therefore, recognizing the MDCT findings of uncomplicated PUD can help appropriately direct patient management, and help prevent the development of complications. To facilitate improved recognition of PUD on abdominal CT, we present an overview of the CT findings of both uncomplicated and complicated PUD, as well as several diagnostic pitfalls which can result in misdiagnosis from peptic ulcer mimics.
[Show abstract][Hide abstract] ABSTRACT: Purpose
To objectively compare residual colonic fluid volume and attenuation of oral sulfate solution (OSS) with four different established cathartic regimens using an automated volumetric software tool at CT colonography (CTC).
This HIPAA-compliant study had institutional review board approval. Volumetric analysis of residual contrast-tagged colonic fluid was performed on CTC studies in 263 adults (mean age 60.1 years; 137M/126F) using an automated volumetric software tool. Twenty-three patients receiving 177 mL OSS (SUPREP; single-bottle purgation) were compared with 60 patients each receiving 45 mL sodium phosphate (NaP), 90 mL NaP (2× NaP), 592 mL (two bottles) magnesium citrate (MgC), and 4,000 mL polyethylene glycol (PEG). All patients received oral contrast cleansing after catharsis. Data were analyzed with unpaired t test with Welch correction and F test.
The mean volume of residual colonic fluid was less with OSS (125 ± 60 mL) than for established cathartic agents: 2× NaP (206 ± 125 mL, P
[Show abstract][Hide abstract] ABSTRACT: Many solid tumors contain an overabundance of phospholipid ethers relative to normal cells. Capitalizing on this difference, we created cancer-targeted alkylphosphocholine (APC) analogs through structure-activity analyses. Depending on the iodine isotope used, radioiodinated APC analog CLR1404 was used as either a positron emission tomography (PET) imaging ((124)I) or molecular radiotherapeutic ((131)I) agent. CLR1404 analogs displayed prolonged tumor-selective retention in 55 in vivo rodent and human cancer and cancer stem cell models. (131)I-CLR1404 also displayed efficacy (tumor growth suppression and survival extension) in a wide range of human tumor xenograft models. Human PET/CT (computed tomography) and SPECT (single-photon emission computed tomography)/CT imaging in advanced-cancer patients with (124)I-CLR1404 or (131)I-CLR1404, respectively, demonstrated selective uptake and prolonged retention in both primary and metastatic malignant tumors. Combined application of these chemically identical APC-based radioisosteres will enable personalized dual modality cancer therapy of using molecular (124)I-CLR1404 tumor imaging for planning (131)I-CLR1404 therapy.
Science translational medicine 06/2014; 6(240):240ra75. DOI:10.1126/scitranslmed.3007646 · 15.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: For patients undergoing screening computed tomography colonography (CTC), an opportunity exists for bone mineral density (BMD) screening without additional radiation exposure using quantitative computed tomography (QCT). This study investigated the use of dual-energy X-ray absorptiometry (DXA)-equivalent QCT Computed Tomography X-Ray Absorptiometry (CTXA) analysis at the hip obtained using CTC examinations using a retrospective asynchronous calibration of patient scans. A cohort of 33 women, age 61.3 (10.6) yr (mean [standard deviation]), had routine CTC using various GE LightSpeed CT scanner models followed after 0-9 mo by a DXA hip BMD examination using a GE Lunar Prodigy machine. Areal bone mineral density (aBMD) and T-scores of the proximal femur were measured from either prone or supine CTC examinations using Mindways QCT Pro software following standard workflow except that the CT scanners were asynchronously calibrated by phantoms scanned retrospectively of the CTC examination without the subject present. CTXA and DXA aBMD were highly correlated (R(2) = 0.907) with a linear relationship of DXA_BMD = 1.297*CTXA_BMD + 0.048. The standard error of estimate (SEE) on the linear fit was 0.053 g/cm(2). CTXA and DXA T-scores showed a linear relationship of DXA_T-score = 1.034*CTXA_T-score + 0.3 and an SEE of 0.379 T-scores. CTXA and DXA aBMD and T-score measurements showed good correlation despite asynchronous scan acquisition and retrospective QCT calibration. The SEE of 0.053 g/cm(2) is on par with the literature comparing Hologic and Lunar DXA devices. The observed relationship between CTXA and Lunar DXA aBMD matches predictions from published cross-calibrations relating CTXA to DXA aBMD measurement. Thus, opportunistic use of CTXA T-scores obtained at the time of CTC could enhance osteoporosis screening.
[Show abstract][Hide abstract] ABSTRACT: Existing and emerging colorectal screening tests can be assessed in terms of the key categories of diagnostic performance, procedural risks, patient acceptability, and cost-effectiveness. To push a new screening test to acceptance, it need not outperform existing strategies in all of these criteria. Rather, a relative advantage in one criterion combined with acceptable performance in the others may be considered adequate. For computed tomographic colonography (CTC), a strong case can be made that this test meets or exceeds optical colonoscopy, the current screening standard, in all of these categories. Published data, including our own experience with CTC screening, will be reviewed to support this claim. Reasons why CTC has not yet achieved its full potential as a valuable screening test for colorectal cancer prevention will also be considered.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: We propose a diverticular disease severity score (DDSS) based on CT colonography (CTC) findings. METHODS: Seventy-nine patients (62 ± 14.5 years) underwent CTC after recovering from an episode of acute diverticulitis. Two independent readers classified each case using a four-point scale (DDSS), based on maximum sigmoid colon wall thickness (MSCWT) and minimum lumen diameter at CTC: 1 = MSCWT <3 mm, lumen diameter ≥15 mm; 2 = MSCWT 3-8 mm, lumen diameter ≥5 mm; 3 = MSCWT ≥8 mm, lumen diameter ≥5 mm; 4 = MSCWT ≥8 mm, lumen diameter <5 mm. Intra- and interobserver reproducibility was evaluated. Of 79 patients, 32 (40 %) underwent surgery after CTC; MSCWT was directly measured on the pathological specimen. RESULTS: Intra- and interobserver reproducibility of DDSS were almost perfect (k = 0.90-0.84). DDSS significantly correlated with the probability of surgery (P = 0.001). After surgery, histopathology revealed acute/chronic diverticular inflammation only in 29 cases, and superimposed sigmoid cancer (n = 2) or Crohn's disease (n = 1) in 3 patients with a DDSS of 4. MSCWT at histopathology correlated with DDSS (P = 0.008). CONCLUSION: DDSS is highly reproducible and correlates with pathological MSCWT. Nearly 1 in 3 patients with a DDSS of 4 had significant superimposed histopathology. CTC with DDSS can provide colorectal surgeons with valuable information. KEY POINTS: • A diverticular disease severity score (DDSS) based on CT colonography is proposed. • This DDSS is based on sigmoid colon wall thickness and lumen diameter. • High scores may be associated with relevant coexisting lesions. • A CTC-based DDSS may influence therapeutic decision-making.
European Radiology 05/2013; 23(10). DOI:10.1007/s00330-013-2882-2 · 4.01 Impact Factor