Lynne M Hurwitz

Duke University, Durham, North Carolina, United States

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Publications (60)160.27 Total impact

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    ABSTRACT: This study sought to compare the accuracy of 2-dimensional transesophageal echocardiography (TEE) and computed tomography angiography (CTA) for noninvasive aortic annular sizing as required for transcatheter aortic valve implantation (TAVI). Direct intraoperative (OR) sizing is the gold standard for aortic annular measurement in surgical aortic valve replacement. Unlike surgical aortic valve replacement, TAVI requires noninvasive assessment of aortic annular dimensions for determining the size of prosthesis to be implanted and controversy exists regarding the best imaging technique for TAVI sizing. Preoperative CTA and OR TEE images of the aortic annulus in 227 patients who underwent proximal aortic surgery with OR annular sizing at the Duke University Medical Center were reviewed. Both imaging techniques were compared with direct OR measurements of aortic annulus diameter using metric sizers as the gold standard. CTA overestimated aortic annulus diameter in 72.2% of cases, with 46.3% >1 TAVI valve-size (>3 mm) overestimations, whereas TEE underestimated aortic annulus diameter in 51.1% of cases, with 16.7% >1 valve-size underestimations. Combining both techniques improved the estimation of aortic annular size. In conclusion, there are limitations to current imaging techniques for noninvasive determination of aortic annular dimensions compared with direct OR sizing. Undersizing by TEE and oversizing by CTA are common and may be related to differences in methods for sizing an elliptical structure. Combining measurements from both techniques would decrease the false exclusion rate for TAVI eligibility because of size mismatch. Copyright © 2015 Elsevier Inc. All rights reserved.
    The American Journal of Cardiology 03/2015; DOI:10.1016/j.amjcard.2015.02.060 · 3.43 Impact Factor
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    ABSTRACT: This study aimed to assess vascular contrast opacification and homogeneity using single-bolus contrast administration with hybrid thoracic and abdominopelvic computed tomographic angiography in patients with severe aortic valve stenosis. Combination electrocardiogram-gated thoracic and dual-source, high-pitch abdominopelvic computed tomographic angiography examinations of 50 patients with severe aortic stenosis between December 2013 and March 2014 were reviewed. Contrast administration was individualized to patient-specific physiology. Image analysis of vascular opacification was obtained and interdependencies of vascular contrast and homogeneity of contrast distribution were assessed. The mean volume of contrast administered was 106 ± 11.7 mL. Mean attenuation was 371 ± 90.7 Hounsfield units (HU) in the thoracic aorta and 388 ± 95.9 HU in the abdominal aorta. Homogeneous opacification was obtained throughout with coefficient of variation of 11%. Procedural planning for transcatheter aortic valve replacement can be achieved using a single-injection bolus contrast protocol in combination with a 2-part multidetector computed tomographic image acquisition technique with optimal opacification of major arterial structures.
    Journal of Computer Assisted Tomography 01/2015; DOI:10.1097/RCT.0000000000000194 · 1.60 Impact Factor
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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; DOI:10.1097/RCT.0000000000000180 · 1.60 Impact Factor
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    ABSTRACT: Purpose To determine the effectiveness of radiologists' search, recognition, and acceptance of lung nodules on computed tomographic (CT) images by using eye tracking. Materials and Methods This study was performed with a protocol approved by the institutional review board. All study subjects provided informed consent, and all private health information was protected in accordance with HIPAA. A remote eye tracker was used to record time-varying gaze paths while 13 radiologists interpreted 40 lung CT images with an average of 3.9 synthetic nodules (5-mm diameter) embedded randomly in the lung parenchyma. The radiologists' gaze volumes ( GV gaze volume s) were defined as the portion of the lung parenchyma within 50 pixels (approximately 3 cm) of all gaze points. The fraction of the total lung volume encompassed within the GV gaze volume s, the fraction of lung nodules encompassed within each GV gaze volume (search effectiveness), the fraction of lung nodules within the GV gaze volume detected by the reader (recognition-acceptance effectiveness), and overall sensitivity of lung nodule detection were measured. Results Detected nodules were within 50 pixels of the nearest gaze point for 990 of 992 correct detections. On average, radiologists searched 26.7% of the lung parenchyma in 3 minutes and 16 seconds and encompassed between 86 and 143 of 157 nodules within their GV gaze volume s. Once encompassed within their GV gaze volume , the average sensitivity of nodule recognition and acceptance ranged from 47 of 100 nodules to 103 of 124 nodules (sensitivity, 0.47-0.82). Overall sensitivity ranged from 47 to 114 of 157 nodules (sensitivity, 0.30-0.73) and showed moderate correlation (r = 0.62, P = .02) with the fraction of lung volume searched. Conclusion Relationships between reader search, recognition and acceptance, and overall lung nodule detection rate can be studied with eye tracking. Radiologists appear to actively search less than half of the lung parenchyma, with substantial interreader variation in volume searched, fraction of nodules included within the search volume, sensitivity for nodules within the search volume, and overall detection rate. © RSNA, 2014 Online supplemental material is available for this article.
    Radiology 10/2014; DOI:10.1148/radiol.14132918 · 6.21 Impact Factor
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    ABSTRACT: Background Preprocedural multidetector computed tomography (MDCT) may identify patients at risk for mechanical complications during lead extraction. Methods To describe the use and feasibility of computed tomography scanning for preprocedural planning of lead extraction, we conducted a retrospective study of high-risk patients, who underwent electrocardiogram (ECG)-gated MDCT before planned lead extraction between January 1, 2012, and March 30, 2013. ResultsAmong 30 patients the mean age was 63 15 years, 60% were male, and 20% had prior sternotomy. Most devices were left sided (93%) and 24 had implantable defibrillators (80%). Indications for extraction included lead malfunction (n = 15; 50%), class I lead advisories (n = 11; 37%), and infection (n = 10; 33%). Overall, there were 65 leads extracted (mean 2.1 leads per patient). One extraction procedure was deferred due to MDCT evidence of significant myocardial perforation with the lead tip > 1 cm beyond the epicardium (n = 1, 3%). MDCT suggestion of lead adherence to central venous structures (n = 13, 43%) was associated with significantly longer laser times (88 +/- 71 seconds vs 30 +/- 37 seconds, P = 0.02) and larger sheath size (14.9 +/- 1.3 vs 13.5 +/- 1.2 French, P = 0.02). MDCT evidence of central venous occlusion or stenosis was not associated with increased laser times. Excluding the patient with MDCT evidence of significant perforation, clinical success was achieved in all patients (n = 29/29). ConclusionsECG-gated MDCT scanning before lead extraction may facilitate the identification of significant perforation and patients at high risk for mechanical complication.
    Pacing and Clinical Electrophysiology 09/2014; 37(10). DOI:10.1111/pace.12485 · 1.25 Impact Factor
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    ABSTRACT: Background. Nontraumatic cerebral air embolism cases are rare. We report a case of an air embolism resulting in cerebral infarction related to angioinvasive cavitary aspergillosis. To our knowledge, there have been no previous reports associating these two conditions together. Case Presentation. A 32-year-old female was admitted for treatment of acute lymphoblastic leukemia (ALL). Her hospital course was complicated by pulmonary aspergillosis. On hospital day 55, she acutely developed severe global aphasia with right hemiplegia. A CT and CT-angiogram of her head and neck were obtained demonstrating intravascular air emboli within the left middle cerebral artery (MCA) branches. She was emergently taken for hyperbaric oxygen therapy (HBOT). Evaluation for origin of the air embolus revealed an air focus along the left lower pulmonary vein. Over the course of 48 hours, her symptoms significantly improved. Conclusion. This unique case details an immunocompromised patient with pulmonary aspergillosis cavitary lesions that invaded into a pulmonary vein and caused a cerebral air embolism. With cerebral air embolisms, the acute treatment option differs from the typical ischemic stroke pathway and the provider should consider emergent HBOT. This case highlights the importance of considering atypical causes of acute ischemic stroke.
    08/2014; 2014:406106. DOI:10.1155/2014/406106
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    ABSTRACT: Purpose: To evaluate the impact of body size and tube power limits in the optimization of fast scanning with high-pitch dual source CT (DSCT).
    Medical Physics 06/2014; 41(6):559-559. DOI:10.1118/1.4889636 · 3.01 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; DOI:10.1007/s00330-014-3120-2 · 4.34 Impact Factor
  • American Journal of Respiratory and Critical Care Medicine 02/2014; 189(3):356-357. DOI:10.1164/rccm.201307-1259IM · 11.99 Impact Factor
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    ABSTRACT: PURPOSE To investigate within the same patient the relationship between radiation dose and noise to patient body size in thoracoabdominal aortic CT angiography (CTA), using non-ECG-assisted high-pitch dual-source and standard-pitch acquisitions. METHOD AND MATERIALS This HIPAA-compliant retrospective study received IRB approval with a waiver of informed consent. Fifty consecutive patients (29 men, 21 women; mean age, 68 years ± 13 standard deviation [SD]; mean body mass index [BMI], 29.9 kg/m2 ± 7) underwent clinically-indicated CTA of the thoracoabdominal aorta using a second-generation dual-source scanner. Standard-pitch (pitch=0.8) unenhanced acquisition was followed by a non-ECG-assisted high-pitch (pitch=1.6-3.0;mean,2.8±0.2) dual-source contrast-enhanced acquisition. Radiation dose was calculated for each patient as CTDIvol and size-specific dose estimate (SSDE). Noise was measured as voxel SD from a region-of-interest in the subcutaneous fat of the thoracic and abdominal wall. The relationship between CTDIvol, SSDE, and noise as a function of BMI was assessed using linear regression models. RESULTS Mean CTDIvol and SSDE (±SD) were significantly lower with high-pitch compared to standard-pitch acquisition (8.2±1.0 vs 10.6±3.0 mGy and 9.0±1.5 vs 11.2±2.1 mGy, respectively [P<.0001]). For each patient, noise was higher with high-pitch compared to standard-pitch (mean noise [±SD], 11.3±2.1 vs 8.7±1.6 in the thorax and 12.6±2.9 vs 9.6±2.5 in the abdomen [P<.0001]). Linear regression analysis showed a significantly positive correlation between CTDIvol and BMI for both standard-pitch (R2=0.47) and high-pitch (R2=0.02). While SSDE was independent of BMI with a standard-pitch, the high-pitch acquisition showed significantly negative correlation between SSDE and BMI (R2=0.33), likely reflecting limitation of the scanner output. Noise showed a significantly positive correlation with BMI for both acquisitions, though the higher slope at high-pitch suggests higher dependency on patient body size. CONCLUSION Non-ECG-assisted high-pitch dual-source acquisition for aortic CTA yields lower radiation dose, at the cost of higher noise in large patients. CLINICAL RELEVANCE/APPLICATION Radiologists should be aware of the higher noise using high-pitch settings in large patients, likely reflecting limitation of the scanner output.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: Although frailty has recently been examined in various populations as a predictor of morbidity and mortality, its effect on thoracic aortic surgery outcomes has not been studied. The objective of the present study was to evaluate the role of frailty in predicting postoperative morbidity and mortality in patients undergoing proximal aortic replacement surgery. A retrospective analysis of a prospectively maintained database was performed for all patients undergoing elective and nonelective proximal aortic operations (root, ascending aorta, and/or arch) at a single-referral institution from June 2005 to December 2012. A total of 581 patients underwent proximal aortic surgery, of whom 574 (98.8%) were included in the present analysis; 7 were excluded because of incomplete data. Frailty was evaluated using an index consisting of age >70 years, body mass index <18.5 kg/m(2), anemia, history of stroke, hypoalbuminemia, and total psoas volume in the bottom quartile of the population. One point was given for each criterion met to determine a frailty score of 0 to 6. Frailty was defined as a score of ≥2. Risk models for length of stay >14 days, discharge to other than home, 30-day composite major morbidity, 30-day composite major morbidity/mortality, and 30-day and 1-year mortality were calculated using multivariate regression modeling. Of the 574 patients, 148 (25.7%) were defined as frail (frailty score ≥2). The unadjusted 30-day/in-hospital and long-term outcomes were significantly worse for the frail versus nonfrail patients in all but 1 of the outcomes analyzed; no difference was found in the 30-day readmission rates between the 2 groups. In the multivariate model, a frailty score of ≥2 was associated with discharge to other than home and 30-day and 1-year mortality. Frailty, as defined using a 6-component frailty index, can serve as an independent predictor of discharge disposition and early and late mortality risk in patients undergoing proximal aortic surgery. These frailty markers, all of which are easily assessed preoperatively, could provide valuable information for patient counseling and risk stratification before proximal aortic replacement.
    The Journal of thoracic and cardiovascular surgery 10/2013; 147(1). DOI:10.1016/j.jtcvs.2013.09.011 · 3.99 Impact Factor
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    ABSTRACT: Aortic stenosis affects many people worldwide with a significant impact on morbidity and mortality with uncorrected, symptomatic aortic valve stenosis carrying mortality of 50 % at one year. Degenerative calcific pathology, the most common cause of aortic stenosis, increases in prevalence with age; estimated prevalence of 5 % in individuals over 75 years of age. Despite the malignant prognosis without valve replacement, many patients are not offered surgery due to advanced age and co-existing medical conditions; reported to be a third of symptomatic patients. In the last several years, transcatheter aortic valve replacement has emerged as an alternative treatment in patients with high or prohibitive open surgical risk. The PARTNER cohort B data, employing the Sapien valve, demonstrated a 20 % absolute mortality benefit at one year compared with medical therapy. In this review, we provide an update of this technology and discuss patient selection, procedural planning, complications, and look toward the future of transcatheter heart valves in the treatment of aortic stenosis.
    Current Cardiology Reports 06/2013; 15(6):367. DOI:10.1007/s11886-013-0367-1
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    ABSTRACT: Purpose: To study Bismuth (Bi) shielding for the breast, organ dose and image quality were compared under the following conditions: (1) tube current modulation (TCM), (2) TCM with a Bi shield placed after topogram, and (3) manually reduced tube current (RTC) with no Bi. Methods: All measurements were performed with a 64‐slice scanner at 120 kVp. Organ dose was measured with MOSFETs using an adult male anthropomorphic phantom with supine breast attachments. The reference exposure and reduced exposure (with 4‐ply Bi shield) was measured with an ion chamber located at the level of the breast. The mA was reduced by normalizing the reference mA to the ratio of the reduced exposure to the reference exposure. Image quality was measured using a high contrast insert placed in the lung. Regions of Interest (ROIs) were drawn in thoracic organs to measure signal‐to‐noise ratio (SNR), percent contrast (%Contrast), noise, and HU values. Results: Organ doses (mGy) for the three scans (TCM, TCM with Bi, and RTC) were 11.1, 6.89, and 6.04 to the breast; 8.83, 8.01, and 7.62 to the lung; and 8.20, 7.36 and 8.40 to the heart, respectively. HU increase was greatest in the TCM with Bi scan for organs closest to the shield. The SNRs were 37.6, 34.1, and 43.3 and the %Contrast values were 349.2, 326.3, and 354.3 with TCM, TCM with Bi, and RTC, respectively. Conclusion: For thoracic CT, this RTC method provides a dose reduction to the breast similar to that of the TCM with Bi. Decrease in SNR and %Contrast in the TCM with Bi scan was expected due to decrease in photons reaching the detectors and beam hardening from the shield, respectively. Increased SNR in RTC scan was due to the increased mA compared to TCM scan at the level of measurement. U.S. NRC Health Physics Fellowship Grant No. NRC‐HQ‐12‐G‐38‐0022
    Medical Physics 06/2013; 40(6):111. DOI:10.1118/1.4814044 · 3.01 Impact Factor
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    ABSTRACT: To evaluate the quantitative and qualitative image quality of pulmonary CT arteriography images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) scanned at differential radiation doses.Materials and MethodsA healthy 56.1 kg Yorkshire pig underwent fluoroscopic placement of a femoral central venous catheter. The catheter was subsequently injected with macerated, previously clotted autologous blood. After pulmonary emboli were visualized in the left lower lobe segmental pulmonary arteries, successive pulmonary arterial CT angiography on a Discovery 750HD MDCT scanner (GE Healthcare) was performed at 700, 400, 200, 100, and 50 mA at 120, 100, and 80 kVp, for a total of 15 scans. Each scan was reconstructed FBP, ASIR (50% blend) and MBIR. Noise (SD) and contrast-to-noise ratios were calculated from ROIs over the left lower lobe segmental pulmonary artery and paraspinous muscle. Selected axial images were scored subjectively for PE visibility and overall image quality.ResultsAveraged across all doses, MBIR reduced noise and improved contrast to noise ratio (CNR) compared to FBP by 73% and 232%, and reduced noise and improved CNR compared to ASIR by 69% and 110%, respectively. The effect was more pronounced in higher noise settings. Averaged across all doses, MBIR improved subjective image quality and diagnostic sensitivity for pulmonary embolism (PE) compared to FBP by 50% and compared to ASIR by 25%. Subjective improvements in image quality were most pronounced in higher noise settings. At 120 kVp/400 mA, readers scored FBP, ASIR, and MBIR images equally. At 100 mA/120 kVp, readers scored FBP and ASIR images as nondiagnostic for detection of PE, while MBIR images were considered of moderate quality but remained diagnostic for detection of PE.ConclusionMBIR reduced image noise and improved CNR for the pulmonary arteries compared to ASIR and FBP across all dose levels. Furthermore, MBIR resulted in higher subjective image quality and improved diagnostic sensitivity for pulmonary embolism, particularly in higher noise settings.
    Journal of Vascular and Interventional Radiology 04/2013; 24(4):S105-S106. DOI:10.1016/j.jvir.2013.01.258 · 2.15 Impact Factor
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    ABSTRACT: Advances in computed tomography (CT) scanners and electrocardiographic gating techniques have resulted in superior image quality of the ascending aorta and increased the use of CT angiography for evaluating the postoperative ascending aorta. Several abnormalities of the ascending aorta and aortic arch often require surgery, and various open techniques may be used to reconstruct the aorta, such as the Wheat procedure, in which both an ascending aortic graft and an aortic valve prosthesis are implanted; the Cabrol and modified Bentall procedures, in which a composite synthetic ascending aorta and aortic valve graft are placed; the Ross procedure, in which the aortic valve and aortic root are replaced with the patient's native pulmonary valve and proximal pulmonary artery; valve-sparing procedures such as the T. David-V technique, which leaves the native aortic valve intact; and more extensive arch repair procedures such as the elephant trunk and arch-first techniques, in which interposition or inclusion grafts are implanted, with or without replacement of the aortic valve. Normal postoperative imaging findings, such as hyperattenuating felt pledgets, prosthetic conduits, and reanastomosis sites, may mimic pathologic processes. Postoperative complications seen at CT angiography that require further intervention include pseudoaneurysms, anastomotic stenoses, dissections, and aneurysms. Radiologists must be familiar with these procedures and their imaging features to identify normal postoperative appearances and complications.
    Radiographics 01/2013; 33(1):73-85. DOI:10.1148/rg.331125090 · 2.73 Impact Factor
  • Conference Paper: Cardiac PET
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    ABSTRACT: LEARNING OBJECTIVES 1) To understand the complimentary role of anatomic and functional imaging in the assessment of CAD and its implications for patient management. ABSTRACT Detection of significant luminal narrowing has been the hallmark to characterize presence and extent of coronary artery disease (CAD) for decades. However, it is now known that characterizations of systemic atherosclerosis burden and inflammation as well as local quality of plaque composition and morphology allow for better characterization of CAD and thus may improve prediction of adverse cardiovascular events. Plaques characterized histologically as thin fibrous cap atheromas with a thin fibrous cap, underlying lipid rich necrotic core, and inflammatory activity have been recognized as vulnerable or high risk plaques. Both positron emission tomography (PET) and cardiac computed tomography (CT) are novel non-invasive technologies that provide morphological (CT) and metabolic (PET) information on atherosclerotic plaque. PET allows for the quantification of 18F-fluorodeoxyglucose (FDG) uptake within the arterial wall, which provides a measure of macrophages activity within atheromatous plaque. Coronary CTA allows for the visualisation of plaque morphology and composition. Thus, integrated imaging by PET/CT permits for co-registration of FGD activity with presence and morphology of plaque and may lead to improved charcaterization of vulnerable plaque and/or vulnerable patients. This course details the methodology and principles of cardiac FDG-PET and coronary CTA and provides an overview on the research with an emphasis on the detection and characterization of vulnerable plaque.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE To identify the optimal monochromatic energy level for visualization of the hepatic arteries on dual energy CT angiographic (CTA) volume rendered (VR) images. METHOD AND MATERIALS This is an IRB-approved study of 29 patients who underwent arterial phase CT of the upper abdomen with dual kVp switching (80 kVp/140 kVp) on a Discovery CT 750HD scanner (GE Healthcare). Datasets were processed with Gemstone Spectral Imaging (GSI) software to derive calculated monochromatic image sets at 40, 50, 60, 70, and 80 keV, from which noise (SD) and contrast-to-noise ratios (CNR) were determined. Standardized volume rendered images from monochromatic 40, 60 and 80 keV, datasets were scored subjectively on a 7 point scale for visualization of the left and right hepatic arteries (1=not visible; 2=visible, but contour difficult to trace; 3=visible with moderate discontinuity; 4=mild discontinuity; 5=continuous with moderate wall irregularity; 6=mild wall irregularity; 7=smooth vessel walls), and a 5 point scale for for overall image quality (1=poor, nondiagnostic image quality; 2=marginal image quality with limited diagnostic value; 3=good image quality with mild noise/artifact; 4=very good image quality typical of ideal standard clinical practice; 5=superior image quality). RESULTS Compared to 80 kEv, average aortic enhancement at 40 keV increased by 346%. Concurrently, noise increased by 170%, and CNR improved by 89%. Compared to 80 kEv, subjective scores for visibility of the left and right hepatic arteries at 40 kEv improved by 15% and 8%, respectively. Overall VR image quality scores improved by 19% from a mean of 3.3 to 3.9. CONCLUSION As the keV is lowered, the attenuation and CNR of contrast-enhanced vessels increase substantially. Less dramatic, but still significant, improvements in subjective hepatic arterial visibility and overall image quality with volume rendering were also seen. These data show that reconstructing monochromatic images for volume rendering appears beneficial, and that using the lowest keV of 40 is optimal. CLINICAL RELEVANCE/APPLICATION Low keV monochromatic image sets reconstructed from dual energy hepatic CTAs improve contrast-to-noise ratios, subjective VR vessel visibility, and overall subjective VR image quality.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE To evaluate the quality of aortic CT angiographic images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) scanned at progressively lower radiation doses. METHOD AND MATERIALS A healthy 56.1 kg Yorkshire pig underwent successive thoracic arterial CT angiography on a Discovery CT 750HD MDCT scanner (GE Healthcare) at progressively lower radiation doses while under general anesthesia. The pig was scanned at 700, 400, 200, 100, and 50 mA at 120, 100, and 80 kVp, for a total of 15 scans. Each scan was reconstructed with FBP, ASIR (50% blend) and MBIR. Noise (SD) and contrast-to-noise ratios (CNR) were calculated from ROIs over the aorta and paraspinous muscle. In addition, selected axial and oblique sagittal images were scored subjectively from 1 to 5 for both aortic wall visibility (1-aortic wall margin difficult or impossible to asses; 5-superior aortic wall visualization) and for overall image quality (1-poor quality, nondiagnostic; 4-good image quality typical of expected clinical practice; 5-superior image quality with no significant noise or artifact). RESULTS Averaged across all doses, MBIR reduced noise by 73% and improved CNR by 227% compared to FBP; MBIR reduced noise by 69% and improved CNR by 107% compared to ASIR. The effect was more pronounced in higher noise settings. At 120 kVp/400 mA, MBIR reduced noise by 50% compared to FBP and 30% compared to ASIR. At 80 kVp/50 mA MBIR reduced noise by 81% compared to FBP and 74% compared to ASIR. Subjective improvements in image quality were only noted in higher noise settings. At 120 kVp/400 mA, readers scored FBP, ASIR, and MBIR images equally. At 120 kVp/50 mA, readers scored FBP and ASIR images as nondiagnostic, while MBIR images were considered of moderate quality but remained diagnostic. At very low doses (80 KvP/50 mA), FBP, ASIR, and MBIR were nondiagnostic. CONCLUSION MBIR reduced image noise compared to ASIR and FBP across all dose levels. Reductions in noise were significantly greater in lower dose settings. While quantitative data suggest that large dose reductions may be possible, qualitative data is more tempered, particularly at very low doses. CLINICAL RELEVANCE/APPLICATION Subjective data suggest that, while still beneficial, the dramatic dose reductions for MBIR implied by quantitative data may be tempered by the waxy appearance of MBIR images at low doses.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
  • Jared Dean Christensen, Lynne Michelle Hurwitz, Daniel Tobias Boll
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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
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    ABSTRACT: The purpose of this study was to investigate gray-scale inversion in nodule detection on chest radiography. Simulated nodules were superimposed randomly onto normal chest radiographs. Six radiologists interpreted 144 chest radiographs during three reading sessions: traditional presentation, inverted gray-scale, and a choice session allowing use of traditional and gray-scale inverted views. Sensitivity and specificity were used to assess accuracy based on presence or absence of a nodule. Gray-scale inversion and choice display sessions resulted in significantly higher nodule detection specificity and decreased sensitivity compared to traditional display. Gray-scale inversion may decrease false-positive nodule findings during chest X-ray interpretation.
    Clinical imaging 09/2012; 36(5):515-21. DOI:10.1016/j.clinimag.2012.01.009 · 0.60 Impact Factor