Daniel T Boll

Duke University Medical Center, Durham, North Carolina, United States

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Publications (137)292.16 Total impact

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    ABSTRACT: The aim of the study was to assess the image quality of multi-detector-row computed tomography (CT) angiographic images of the thoracic aorta reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction, and model-based iterative reconstruction (MBIR) at different kVp and mA settings. A healthy 56.1-kg Yorkshire pig underwent sequential arterial CT angiograms on a 64-slice multi-detector-row CT scanner (Discovery CT 750HD; GE Healthcare Inc, Milwaukee, Wis) at progressively lower kVp and mA settings. At 120-, 100-, and 80-kVp levels, the pig was scanned at 700, 400, 200, 100, and 50 mA at, for a total of 15 scans. Each scan was reconstructed with FBP, adaptive statistical iterative reconstruction (50% blend), and MBIR. Relative noise and contrast-to-noise ratio (CNR) were calculated from regions of interest over the aorta and paraspinous muscle. In addition, selected axial and oblique sagittal images were scored subjectively for both aortic wall visibility and for overall image quality. Averaged across all kVp and mA variations, MBIR reduced relative noise by 73.9% and improved CNR by 227% compared with FBP; MBIR reduced relative noise by 63.4% and improved CNR by 107% compared with ASIR. The effects were more pronounced in lower tube output settings. At 100 kVp/700 mA, MBIR reduced noise by 57% compared with FBP and 40% compared with ASIR. At 100 kVp/50 mA, MBIR reduced noise by 82% compared with FBP and 75% compared with ASIR. Subjective improvements in image quality were noted only in higher noise settings. Model-based iterative reconstruction reduces relative noise and improves CNR compared with ASIR and FBP at all kVp and mA settings, which were significantly greater at lower mA settings.
    Journal of computer assisted tomography. 12/2014;
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    ABSTRACT: To evaluate the performance of a prototype, fully-automated post-processing solution for whole-liver and lobar segmentation based on MDCT datasets.
    Abdominal Imaging 10/2014; · 1.91 Impact Factor
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    ABSTRACT: To assess the impact of patient habitus, acquisition parameters, detector efficiencies, and reconstruction techniques on the accuracy of iodine quantification using dual-source dual-energy CT (DECT).
    European radiology. 10/2014;
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    ABSTRACT: Recent technologic advances in computed tomography (CT)-enabling the nearly simultaneous acquisition of clinical images using two different x-ray energy spectra-have sparked renewed interest in dual-energy CT. By interrogating the unique characteristics of different materials at different x-ray energies, dual-energy CT can be used to provide quantitative information about tissue composition, overcoming the limitations of attenuation-based conventional single-energy CT imaging. In the past few years, intensive research efforts have been devoted to exploiting the unique and powerful opportunities of dual-energy CT for a variety of clinical applications. This has led to CT protocol modifications for radiation dose reduction, improved diagnostic performance for detection and characterization of diseases, as well as image quality optimization. In this review, the authors discuss the basic principles, instrumentation and design, examples of current clinical applications in the abdomen and pelvis, and future opportunities of dual-energy CT. © RSNA, 2014.
    Radiology 05/2014; 271(2):327-42. · 6.34 Impact Factor
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    ABSTRACT: PurposeTo investigate variation in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) pharmacokinetic parameter measurements between different methods of precontrast tissue relaxation (T10) estimation: pixel-based mapping versus a fixed reference value.Materials and Methods In 15 DCE-MRI studies the female pelvis, uterine fibroids, the left psoas muscle, and the fifth lumbar vertebral body were chosen to represent tissues with varying perfusion characteristics. All DCE-MRI studies were processed using a variable flip angle T10 map and a fixed T10 reference value of 1000 msec. A subset of five DCE-MRI studies were each processed multiple times using the fixed T10 method with the reference T10 ranging from 0–2000 msec in 100-msec increments. Pharmacokinetic measurements of Ktrans, kep, ve, and initial area under the gadolinium curve (iAUGC) were performed maintaining the identical position for region of interest placement on each structure.ResultsThe mean difference in pharmacokinetic output between the pixel-based T10 map and the fixed T10 reference value ranged from 6.6% for kep in the muscle to 54.9% for iAUGC in the vertebral body. At lower T10 (<1000 msec) aberrations in T10 estimation resulted in a larger error. Accurate measurement of T10 for each structure subsequently incorporated as a fixed T10 reference value yielded relative differences from −41.8% to 22.3% compared to the pixel-based T10 map.Conclusion Direct comparison of pharmacokinetic parameters derived from a pixel-based approach versus a reference value uniformly applied to all pixels for T10 estimation is impeded by the inherent spatial heterogeneity of T10 within tissues. J. Magn. Reson. Imaging 2014;39:1136–1145. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 05/2014; 39(5). · 2.57 Impact Factor
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    ABSTRACT: This retrospective study assessed whether dual-source high-pitch computed tomographic angiography (CTA) offered advantages over single-source standard-pitch techniques in the evaluation of the ascending aorta. Twenty patients who received both thoracic dual-source high-pitch and single-source standard-pitch CTAs within 1 year were assessed. Dual-source CTAs were performed; standard-pitch imaging used dose-modulated 120 kVp/150 mAs and 0.8 pitch compared with high-pitch protocols employing dose-modulated 120 kVp/250 mAs and 2.4 target pitch. Radiation dose was documented. Contrast-to-noise ratios (CNRs) at sinuses of the Valsalva (CNRValsalva) and ascending aorta (CNRAorta) were calculated. Dose/CNR for each technique was compared with paired t-tests. Motion at aortic valve, aortic root and ascending aorta were assessed with four-point scales and Mann-Whitney U tests; longitudinal extension of motion was compared with paired t-tests. Significantly lower motion scores for high-pitch, compared with standard-pitch acquisitions for aortic annulus, 0 vs. 2, aortic root, 0 vs. 3, and ascending aorta, 0 vs. 2, were achieved. Significantly reduced longitudinal extension of motion at aortic root, 4.9 mm vs 15.7 mm, and ascending aorta, 4.9 mm vs 21.6 mm, was observed. Contrast was not impacted: CNRValsalva, 45.6 vs 46.3, and CNRAorta, 45.3 vs 47.1. CTDIvol was significantly decreased for high-pitch acquisitions, 13.9 mGy vs 15.8 mGy. Dual-source high-pitch CTAs significantly decreased motion artefact without negatively impacting vascular contrast and radiation dose. • Dual-source high-pitch CTA significantly decreased motion artefact of the ascending aorta. • Dual-source high-pitch CTA did not negatively impact on vascular contrast. • Dual-source high-pitch CTA significantly decreased radiation dose compared with single-source standard-pitch acquisitions.
    European Radiology 02/2014; · 4.34 Impact Factor
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    ABSTRACT: PURPOSE To evaluate the intrinsic variability in radiation dose delivery of CT scanners in clinical use, independent of patient-specific factors. METHOD AND MATERIALS We identified colon cancer, lung cancer, and renal stone patients who underwent the same CT protocol at least twice between 1/2007 and 2/2013. Evaluating patients undergoing multiple scans with identical protocols allowed us to control for any patient- and protocol-specific factors which could affect CT dose. Patient and dose data was taken from DICOM headers and dose sheets in PACS. We performed multivariate analysis to characterize the dose variation for each patient, and to identify any significant cofactors in this variability. We used the "total exam Dose Length Product" (DLP) in our analyses. CT protocols were: (a) Abdomen/Pelvis with IV contrast (A/P), (b) Chest/Abdomen/Pelvis with IV contrast (C/A/P), (c) Renal Stone, and (d) Chest without IV contrast. RESULTS 2606 patients underwent 12,632 repeat CT scans (mean 4.8, range 2-33 repeat scans/patient). There were 875 A/P, 4620 C/A/P, 1053 Renal Stone, and 6084 Chest CT scans. The per-patient dose variation was identified, then normalized using coefficients of variation, and ratios of maximum dose to minimum dose. In both cases, a higher value indicates higher dose variability. There was statistically significant variation across all patients and protocols (p<0.0001). For the four protocols, the coefficients of variability were 0.22, 0.23, 0.32, and 0.25 and maximum/minimum ratios were 1.6, 1.8, 2.0, and 2.0 (i.e. on average, the maximum dose was 60-100% higher than the minimum dose), respectively. ANOVA identified CT table height, patient size, scanner manufacturer, and scanner model as statistically significant covariates/factors (p<0.0001). No effect was seen for patient gender or age. For all protocols, there was a trend toward decreasing dose over time. CONCLUSION There is a statistically significant variation in the radiation dose delivered to a single patient undergoing repeat identical CT scans which varies by scanner and is higher in large patients. The data suggests that there are opportunities to reduce this variability by careful monitoring of key factors, CT table height being one example. CLINICAL RELEVANCE/APPLICATION Evaluation and scrutiny of CT dose delivery in clinical practice allows for determination of the intrinsic and controllable variability in an attempt to achieve more consistent patient care.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
  • Radiology 11/2013; 269(2):620-1. · 6.34 Impact Factor
  • Article: Response.
    Tobias J Heye, Daniel T Boll
    Radiology 11/2013; 269(2):621. · 6.34 Impact Factor
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    ABSTRACT: With the expansion of cross-sectional imaging, the number of renal lesions that are incidentally discovered has increased. Multidetector CT (MDCT) is the investigation of choice for characterising and staging renal lesions. Although a definitive diagnosis can be confidently posed for most of them, a number of renal lesions remain indeterminate following MDCT. Further imaging tests are therefore needed, with subsequent increase of healthcare costs, radiation exposure, and patient anxiety. By addressing most of the issues with conventional MDCT imaging, dual-energy MDCT can improve the diagnosis of renal lesions and, potentially, may represent a paradigm shift from a merely attenuation-based to a material-specific spectral imaging investigation. The purpose of this review is to provide an overview of current clinical applications of dual-energy CT in the evaluation of renal lesions. Key Points • As MDCT expands, an increasing number of renal lesions are serendipitously discovered. • With conventional MDCT, technical issues affect the diagnosis of renal lesions. • Dual-energy CT addresses some of the drawbacks of conventional MDCT. • Dual-energy CT may represent a paradigm shift for renal lesions imaging.
    European Radiology 10/2013; · 4.34 Impact Factor
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    ABSTRACT: OBJECTIVE. The purpose of this article is to validate an automated screening method for evaluation of hepatic steatosis or siderosis. MATERIALS AND METHODS. This was a two-part study, with retrospective and prospective portions. First, 130 consecutive abdominal MRI examinations, including both the automated algorithm and reference standard fat and iron quantification, were retrospectively identified. The algorithm's performance was validated against the reference standard and was compared with the performance of three expert readers. Subsequently, 39 subjects undergoing liver MRI were prospectively identified and enrolled. These subjects were scanned with a protocol where quantification sequences were either performed or not performed on the basis of the recommendation of the algorithm. Total examination time in these subjects was compared with examination times in the 90 subjects from the retrospective cohort who had undergone a similar liver MRI protocol with complete quantification. RESULTS. The automated algorithm was accurate in determining the presence of deposition disease (93.1%), with no significant difference between its conclusions and those of any of the readers (p = 0.48-1.0). Use of the algorithm resulted in a small but statistically significant time savings compared with performing quantification in all subjects (28 minutes 56 seconds vs 31 minutes 20 seconds; p < 0.05). CONCLUSION. Automated screening for hepatic steatosis and siderosis can be performed in real time during abdominal MRI examinations, can save total scan time compared with always performing quantification, and could serve as a gatekeeper for dedicated quantification sequences.
    American Journal of Roentgenology 09/2013; 201(3):583-8. · 2.90 Impact Factor
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    ABSTRACT: OBJECTIVE. The purpose of this article is to evaluate contrast-enhanced (CE) MR venography (MRV) with a blood-pool agent for detection of abdominopelvic and lower extremity deep venous thrombosis (DVT) compared with a conventional unenhanced gradient-recalled echo (GRE) MRV technique. MATERIALS AND METHODS. This retrospective study was performed on 30 patients (mean age, 52.7 years; 15 men and 15 women) referred for MRV between March 2010 and November 2010 for evaluation of lower extremity or abdominopelvic DVT. All patients underwent a GRE sequence followed by a CE T1-weighted sequence with gadofosveset, a blood-pool agent. The abdominopelvic and lower extremity venous system was divided into 13 segments. The presence of acute or chronic DVT was assessed by six radiologists, as well as qualitative and quantitative assessments of each venous segment. Image acquisition and interpretation times were also tabulated. RESULTS. The sensitivity and specificity for acute DVT were 91.0% and 99.8%, respectively, on CE MRV compared with 80.8% and 95.8%, respectively, on GRE MRV (p = 0.077 and p < 0.001). The sensitivity and specificity for chronic DVT were 84.4% and 98.4%, respectively, on CE MRV and 64.5% and 95.6%, respectively, on GRE MRV (p < 0.001 for both). Subjective ratings of vein visualization, signal homogeneity, and confidence pertaining to DVT diagnosis were significantly higher with the CE images (p < 0.001). The contrast-to-noise ratio for CE images was similar or significantly higher for all venous segments. Image acquisition and radiologist interpretation times on the CE studies were decreased (p < 0.001). CONCLUSION. Gadofosveset-enhanced MRV had equal or higher sensitivity and specificity for detection of DVT than did GRE MRV, with decreased time for image acquisition and interpretation.
    American Journal of Roentgenology 07/2013; 201(1):208-14. · 2.90 Impact Factor
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    ABSTRACT: BACKGROUND: To evaluate the contrast agent performance of Gd-EOB-DTPA and Gd-BOPTA for detection and assessment of extrahepatic findings, semi-quantitatively and qualitatively. METHODS: 13 patients with 19 extrahepatic lesions underwent liver MRI with Gd-EOB-DTPA and Gd-BOPTA. Quantitative and relative SNR measurements were performed in each dataset in the arterial and portalvenous phase within the extrahepatic lesion, aorta, inferior vena cava, portal vein, spleen, pancreas and renal cortex. Further, relative CNR measurements were performed. Three readers assessed contrast quality using a five-point scale and choosing the preferred image dataset. Statistical analysis consisted of a Student's t-test with p < 0.05 deemed significant, a weighted kappa statistic for assessment of interobserver variability and an ROC analysis. RESULTS: Mean SNR after injection of Gd-BOPTA was significantly higher compared with Gd-EOB-DTPA for all measurements (p < 0.05). Mean relative SNR was also higher for Gd-BOPTA, but without being statistically significant. There was no significant difference in relative CNR. Interobserver agreement for selection of image preference was moderate (mean weighted kappa 0.485). The area under the curve for the ROC-analysis regarding contrast agent performance was 0.464. CONCLUSION: Even though mean SNR is significantly higher after injection of Gd-BOPTA compared with Gd-EOB-DTPA, there is no significant difference in relative CNR with extrahepatic lesions being assessed equally well. Visual impression may differ after injection of Gd-EOB-DTPA, but does not influence image interpretation. Extrahepatic findings can be assessed similarly to MRI after injection of Gd-BOPTA.
    BMC Medical Imaging 03/2013; 13(1):10. · 1.09 Impact Factor
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    ABSTRACT: PURPOSE: To determine the reproducibility of TWIST-derived (Time-Resolved Angiography with Interleaved Stochastic Trajectories) quantitative dynamic contrast enhanced (DCE) MRI in a uterine fibroid model. MATERIALS AND METHODS: The institutional review board approved this retrospective study. Dynamic contrast-enhanced TWIST datasets from 15 randomly selected 1.5 Tesla pelvic MR studies were postprocessed. Five readers recorded kinetic parameters (K(trans) [volume transfer constant], v(e) [extracellular extravascular space volume], k(ep) [flux rate constant], iAUC [initial area under the gadolinium-time curve]) of the largest uterine fibroid using three region-of-interest (ROI) selection methods. Measurements were randomized and repeated three times, and measures of reproducibility were calculated. RESULTS: The intra-rater coefficients of variation (CVs, brackets indicate 95% confidence intervals) varied from 4.6% to 7.6% (K(trans) 7.6% [6.1%, 9.1%], k(ep) 7.2% [5.9%, 8.5%], v(e) 4.6% [3.8%, 5.4%], and iAUC 7.2% [6.1%, 8.3%]). v(e) was the most reproducible (P < 0.05). Inter-rater reproducibility was significantly (P < 0.05) greater for the large ROI method (range of intraclass correlation coefficients [ICCs] = 0.80-0.98 versus 0.48-0.63 [user-defined ROI] versus 0.41-0.69 [targeted ROI]). The uterine fibroid accounted for the greatest fraction of variance for the large ROI method (range across kinetic parameters: 83-98% versus 56-69% [user-defined ROI] versus 47-74% [targeted ROI]). The reader accounted for the greatest fraction of variance for the user-defined ROI method (0.4-14.1% versus 0.1-3.0% [large ROI] versus <0.1-1.5% [targeted ROI]). CONCLUSION: Changes in TWIST-derived DCE-MRI kinetic parameters of up to 9-15% may be attributable to measurement error. Large DCE-MRI regions of interest are the most reproducible across multiple readers. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 12/2012; · 2.57 Impact Factor
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    ABSTRACT: Purpose:To compare the inter- and intraobserver variability with manual region of interest (ROI) placement versus that with software-assisted semiautomatic lesion segmentation and histogram analysis with respect to quantitative dynamic contrast material-enhanced (DCE) MR imaging determinations of the volume transfer constant (K(trans)).Materials and Methods:The study was approved by the institutional review board and compliant with HIPAA. The requirement to obtain informed consent was waived. Fifteen DCE MR imaging studies of the female pelvis defined the study group. Uterine fibroids were used as a perfusion model. Three varying types of lesion measurements were performed by five readers on each study by using DCE MR imaging perfusion analysis software with manual ROI placement and a semiautomatic lesion segmentation and histogram analysis solution. Intra- and interreader variability of measurements of K(trans) with the different measurement types was calculated.Results:The overall interobserver variability of K(trans) with manual ROI placement (mean, 28.5% ± 9.3) was reduced by 42.5% when the semiautomatic, software-assisted lesion measurement method was used (16.4% ± 6.2). Whole-lesion measurement showed the lowest interobserver variability with both measurement methods (20.1% ± 4.3 with the manual method vs 10.8% ± 2.6 with the semiautomatic method). The overall intrareader variability with the manual ROI method (7.6% ± 10.6) was not significantly different from that with the semiautomatic method (7.3% ± 10.8), but the intraclass correlation coefficient for intrareader reproducibility improved from 0.86 overall with the manual method to 0.99 with the semiautomatic method.Conclusion:A semiautomatic lesion segmentation and histogram analysis approach can provide a significant reduction in interobserver variability for DCE MR imaging measurements of K(trans) when compared with manual ROI methods, whereas intraobserver reproducibility is improved to some extent.© RSNA, 2012.
    Radiology 12/2012; · 6.34 Impact Factor
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    ABSTRACT: Purpose:To test the reproducibility of model-derived quantitative and semiquantitative pharmacokinetic parameters among various commercially available perfusion analysis solutions for dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging.Materials and Methods:The study was institutional review board approved and HIPAA compliant, with waiver of informed consent granted. The study group consisted of 15 patients (mean age, 44 years; range, 28-60 years), with 15 consecutive 1.5-T DCE MR imaging studies performed between October 1, 2010, and December 27, 2010, prior to uterine fibroid embolization. Studies were conducted by using variable-flip-angle T1 mapping and four-dimensional, time-resolved MR angiography with interleaved stochastic trajectories. Images from all DCE MR imaging studies were postprocessed with four commercially available perfusion analysis solutions by using a Tofts and Kermode model paradigm. Five observers measured pharmacokinetic parameters (volume transfer constant [K(trans)], v(e) [extracellular extravascular volume fraction], k(ep)[K(trans)/v(e)], and initial area under the gadolinium curve [iAUGC]) three times for each imaging study with each perfusion analysis solution (between March 13, 2011, and September 8, 2011) by using two different region-of-interest methods, resulting in 1800 data points.Results:After normalization of data output, significant differences in mean values were found for the majority of perfusion analysis solution combinations. The within-subject coefficient of variation among perfusion analysis solutions was 48.3%-68.8% for K(trans), 37.2%-60.3% for k(ep), 27.7%-74.1% for v(e), and 25.1%-61.2% for iAUGC. The intraclass correlation coefficient revealed only poor to moderate consistency among pairwise perfusion analysis solution comparisons (K(trans), 0.33-0.65; k(ep), 0.02-0.81; v(e), 20.03 to 0.72; and iAUGC, 0.47-0.78).Conclusion:A considerable variability for DCE MR imaging pharmacokinetic parameters (K(trans), k(ep), v(e), iAUGC) was found among commercially available perfusion analysis solutions. Therefore, clinical comparability across perfusion analysis solutions is currently not warranted. Agreement on a postprocessing standard is paramount prior to establishing DCE MR imaging as a widely incorporated biomarker.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120278/-/DC1.
    Radiology 12/2012; · 6.34 Impact Factor
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    ABSTRACT: PURPOSE CTA evaluation of the aorta can be problematic due to cardiac motion artifact during conventional non-ECG gated helical single source standard pitch (SS SP) CTA acquisition. Dual source non-ECG gated high pitch (DS HP) CTA is an alternative technique that may reduce motion artifact without increasing radiation dose or compromising diagnostic image quality. This study compares dose and image quality of DS HP vs SS SP CTA of the thoracic aorta. METHOD AND MATERIALS In this IRB-approved study we evaluated 20 patients who had both a DS HP and comparison SS SP CTA of the thoracic aorta. HP exams were performed on a dual source 64 MDCT scanner (Definition, Siemens Medical Systems) with the following settings: 120 kVp, qual ref mAs 250, automatic pitch adjustment (1.85-2.4), rotation time 0.33 s. SS SP CTAs were acquired on a 64 MDCT with identical parameters except for pitch (1.375) and rotation time, 0.5-0.8 s. Weight-based contrast dosing of IsoVue 370 was used for all scans at the same injection rate. CTDIvol was recorded for all exams. Quantitative image quality was assessed by calculating contrast to noise (CNR) at the sinuses of Valsalva (CNRv) and ascending aorta (CNRa). Qualitative assessment was performed by randomized, blinded dual reader consensus for wall motion artifact at the aortic valve annulus, sinuses of Valsalva and ascending aorta on a 4-point scale (0=no motion, 3=severe). Statistical analysis with paired t-test evaluated corresponding qualitative and quantitative parameters. RESULTS Mean CTDI for DS HP vs. SS SP CTA was lower (13.9±2.4 vs. 15.9±4.0, respectively, p=0.08). CNR analysis showed a marginal increase in mean CNRv (46.3 vs. 45.6, p=0.79), and mean CNRa (47.1 vs. 45.3, p=0.52), for the HP protocol. There were, however, significant improvements in image quality in relation to motion for DS HP vs. SS SP technique (p<0.05), with mean scores assessing wall motion artifacts at the level of the annulus (0.4 vs. 1.8), sinuses of Valsalva (0.7 vs. 2.0), and ascending aorta (0.6 vs. 1.8). CONCLUSION DS HP CTA significantly decreases motion-related artifact of the thoracic aortic without decreasing CNR compared to SS SP CTA at comparable radiation dose levels. CLINICAL RELEVANCE/APPLICATION DS HP CTA may result in decreased motion artifact of the thoracic aorta thereby potentially improving diagnostic accuracy without negatively impacting CNR or patient radiation dose.
    Single Tube Standard Pitch Computed Tomographic Angiography (CTA) of the Thoracic Aorta: Quantitative and Qualitative Assessment of Image Quality and Radiation Dose. Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
  • Daniel Tobias Boll, Tobias Heye, Sebastian Feuerlein
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    ABSTRACT: PURPOSE To assess accuracy of iodine quantification based on spectral dual-energy CT (DECT) extraction with additional noise reduction using iterative reconstruction in simulated normal and obese patient environments. METHOD AND MATERIALS Two custom-designed DECT phantoms containing 10 vials with iodine concentrations representing arterial/parenchymal enhancement ranging from water-isodensity to ~150 HU and 40 vials simulating enhancement seen in non-diluted thoracic inlet vasculature, and urinary bladder/renal collecting systems of up to ~2000 HU. DECT acquisition was performed using a dual-source scanner at 140kVp / 90mAs and 80kVp / 495mAs. Backprojection-based soft tissue kernels and corresponding iteratively reconstructed kernels generated dual-energy series used for iodine extraction. Fractional variations between known and spectrally determined iodine concentration were calculated for each concentration step; paired t-tests evaluated variations between backprojected and iteratively reconstructed datasets for normal and obese phantoms. Bland Altman plots with regression analyses assessed concentration differences observed in backprojected and iteratively reconstructed data. RESULTS For backprojected data, mean concentration variations of 8.7% ± 8.4 and 12.2% ± 6.3 were detected in normal/obese phantoms, respectively, compared to significantly less variation observed in iteratively reconstructed data with 6.1% ± 6.2 and 11.0% ± 6.5. Dual-energy quantification systematically overestimated concentrations in lower concentration ranges and underestimated concentrations in higher concentration ranges. Regression analyses showed cubic distribution of concentration differences for backprojected, R2=0.697, and linear distribution for iteratively reconstructed data, R2=0.701. CONCLUSION Spectral DECT-based iodine quantification is able to accurately quantify iodine in phantoms simulating normal and large patients; iterative reconstruction improves the accuracy of iodine detection. Systematic deviations of the spectrally determined iodine concentrations could potentially be corrected with weighting curves. CLINICAL RELEVANCE/APPLICATION Habitus limits accuracy to detect subtle iodine uptake. By combining dual-energy iodine extraction with iterative reconstruction, accuracy of detecting subtle iodine uptake could be improved.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE To investigate differences in noise reduction on standard of care (SOC) and low dose (LD) abdominal MDCT when using adaptive statistical iterative reconstruction (ASiR) or model based iterative reconstruction (MBIR) algorithm in patients with different body habitus. METHOD AND MATERIALS This prospective, multi-center HIPAA-compliant study was IRB-approved. 24 patients (mean age, 61±9 ys) underwent both a SOC and LD [120 kVp, auto mA with noise index on 0.625mm slices of 43 HU for SOC and 70 HU for LD (projected 70% dose reduction)], 64-slice MDCT (750HD; GE) of the abdomen. SOC and LD scans were reconstructed with filtered back projection (FBP), ASiR (40% blend) and MBIR at a slice thickness of 2.5mm. Image noise (S.D.) was measured in subcutaneous fat. Patient size was measured as the cross-sectional area (mm2) from a CT image at the level of the celiac artery. Repeated-measures analysis of variance with Bonferroni correction was used to compare the differences in image noise. The generalized linear model was used to analyze the influence of CT dose and body habitus on image noise. RESULTS Mean image noise was 17.4±3.4 for FBP, 13.2±2.8 for ASiR, 10.7±4.9 for MBIR in SOC scans, and 25.6±6.7 for FBP, 18.9±4.4 for ASiR, and 11.6±7.8 for MBIR in LD scans. ASiR compared to FBP significantly reduced image noise by 24.6% and 25.3% in SOC and LD scans, respectively (p<.0001). MBIR compared to FBP significantly reduced image noise by 38.3% and 53.0% in SOC and LD scans, respectively (p<.0001). Image noise was significantly influenced by dose when using FBP and ASiR (p<.0001 each), but not when using MBIR. Image noise was significantly influenced by body habitus using MBIR (p=.013), but not when using FBP and ASiR. The increase in image noise from SOC to LD was similar for FBP and ASiR (30%/29.3%), but was significantly lower for MBIR (7.9%, p<.0001). CONCLUSION MBIR consistently reduces noise better than ASiR on both SOC and LD CT images. The ability of MBIR in noise reduction is not influenced by CT dose, but was dependent on body habitus as opposed to FBP and ASiR. This is likely due to the fact that MBIR models the entire x-ray beam rather than assuming that it is ideal. CLINICAL RELEVANCE/APPLICATION With MBIR a lower increase of image noise from SOC to LD CT can be achieved than with FBP or ASiR, which may be advantageous in patients with expected high image noise in LD CT.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE: To evaluate the value of hepatobiliary phase imaging for detection and characterization of hepatocellular carcinoma (HCC) in liver MRI with Gd-EOB-DTPA, in a North American population. MATERIALS AND METHODS: One hundred MRI examinations performed with the intravenous injection of Gd-EOB-DTPA in patients with cirrhosis were reviewed retrospectively. Nodules were classified as HCC (n = 70), indeterminate (n = 33), or benign (n = 22). Five readers independently reviewed each examination with and without hepatobiliary phase images (HBP). Lesion conspicuity scores were compared between the two readings. Lesion detection, confidence scores, and receiver operating characteristic (ROC) analysis were compared. RESULTS: Lesion detection was slightly improved for all lesion types with the inclusion of the HBP, and was substantially higher for small HCCs (96.0% versus 85.3%). Mean confidence scores for the diagnosis of HCC increased for HCCs overall and each size category (P < 0.001). Diagnostic performance improved with the addition of the HBP (aggregate AROC 87.7% versus 80.0%, P < 0.01), and sensitivity for characterization improved (90.9% versus 78.3%, P < 0.01) while specificity was unchanged. CONCLUSION: Hepatobiliary phase imaging may improve small lesion detection (<1 cm) and characterization of lesions in general, in MRI of the cirrhotic liver with Gd-EOB-DTPA. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 09/2012; · 2.57 Impact Factor

Publication Stats

1k Citations
292.16 Total Impact Points


  • 2008–2014
    • Duke University Medical Center
      • Department of Radiology
      Durham, North Carolina, United States
  • 2013
    • Assistance Publique – Hôpitaux de Paris
      • Department of Radiology
      Lutetia Parisorum, Île-de-France, France
  • 2012
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States
  • 2011
    • University of Zurich
      Zürich, Zurich, Switzerland
  • 1999–2011
    • Universität Ulm
      • Clinic of Cardiac, Thoracic and Vascular Surgery
      Ulm, Baden-Württemberg, Germany
  • 2003–2006
    • Cleveland State University
      Cleveland, Ohio, United States
  • 2005
    • Case Western Reserve University
      • Department of Radiology (University Hospitals Case Medical Center)
      Cleveland, OH, United States
  • 2004
    • Case Western Reserve University School of Medicine
      • Department of Radiology
      Cleveland, Ohio, United States