Lynne M Hurwitz

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

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Publications (33)98.67 Total impact

  • [Show abstract] [Hide abstract]
    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; · 6.34 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: 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; · 3.41 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.
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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. · 2.79 Impact Factor
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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. · 0.73 Impact Factor
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    ABSTRACT: The purpose of this study was to assess the radiation dose distribution and image quality for organ-based dose modulation during adult thoracic MDCT. Organ doses were measured using an anthropomorphic adult female phantom containing 30 metal oxide semiconductor field-effect transistor detectors on a dual-source MDCT scanner with two protocols: standard tube current modulation thoracic CT and organ-based dose modulation using a 120° radial arc. Radiochromic film measured the relative axial dose. Noise was measured to evaluate image quality. Breast tissue location across the anterior aspect of the thorax was retrospectively assessed in 100 consecutive thoracic MDCT examinations. There was a 17-47% decrease (p = < 0.05) in anterior thoracic organ dose and a maximum 52% increase (p = < 0.05) in posterior thoracic organ dose using organ-based dose modulation compared with tube current modulation. Effective dose (SD) for tube current modulation and organ-based dose modulation were 5.25 ± 0.36 mSv and 4.42 ± 0.30 mSv, respectively. Radiochromic film analysis showed a 30% relative midline anterior-posterior gradient. There was no statistically significant difference in image noise. Adult female breast tissue was located within an average anterior angle of 155° (123-187°). Organ-based dose modulation CT using an anterior 120° arc can reduce the organ dose in the anterior aspect of the thorax with a compensatory organ dose increase posteriorly without impairment of image quality. Laterally located breast tissue will have higher organ doses than medially located breast tissue when using organ-based dose modulation. The benefit of this dose reduction must be clinically determined on the basis of the relationship of the irradiated organs to the location of the prescribed radial arc used in organ-based dose modulation.
    American Journal of Roentgenology 07/2012; 199(1):W65-73. · 2.90 Impact Factor
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    ABSTRACT: The purpose of this study was to assess the difference in absorbed organ dose and image quality for MDCT neck protocols using automatic tube current modulation alone compared with organ-based dose modulation and in-plane thyroid bismuth shielding. An anthropomorphic female phantom with metal oxide semiconductor field effect transistor (MOSFET) detectors was scanned on a 64-MDCT scanner. The protocols included a reference neck CT protocol using automatic tube current modulation and three modified protocols: organ-based dose modulation, automatic tube current modulation with thyroid shield, and organ-based dose modulation with thyroid shield. Image noise was evaluated quantitatively with the SD of the attenuation value, and subjectively by two neuroradiologists. Organ-based dose modulation, automatic tube current modulation with thyroid shield, and organ-based dose modulation with thyroid shield protocols reduced the thyroid dose by 28%, 33%, and 45%, respectively, compared with the use of automatic tube current modulation alone (p ≤ 0.005). Organ-based dose modulation also reduced the radiation dose to the ocular lens (33-47%) compared with the use of automatic tube current modulation (p ≤ 0.04). There was no significant difference in measured noise and subjective image quality between the protocols. Both organ-based dose modulation and thyroid shields significantly reduce the thyroid organ dose without degradation of subjective image quality compared with automatic tube current modulation. Organ-based dose modulation has the additional benefit of dose reduction to the ocular lens.
    American Journal of Roentgenology 05/2012; 198(5):1132-8. · 2.90 Impact Factor
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    ABSTRACT: The purpose of this study was to assess the effect of peak kilovoltage on radiation dose and image quality in adult neck MDCT. An anthropomorphic phantom with metal oxide semiconductor field effect transistor detectors was imaged with a 64-MDCT scanner. The reference CT protocol called for 120 kVp, and images obtained with that protocol were compared with CT images obtained with protocols entailing 80, 100, and 140 kVp. All imaging was performed with automatic tube current modulation. Organ dose and effective dose were determined for each protocol and compared with those obtained with the 120-kVp protocol. Image noise was evaluated objectively and subjectively for each protocol. The highest organ doses for all protocols were to the thyroid, ocular lens, skin, and mandible. The greatest reductions in organ dose were for the bone marrow of the cervical spine and mandible: 43% and 35% with the 100-kVp protocol and 63% and 53% with the 80-kVp protocol. Effective dose decreased as much as 9% with the 100-kVp protocol and 12% with the 80-kVp protocol. Use of the 140-kVp protocol was associated with an increase in organ dose as high as 64% for bone marrow in the cervical spine and a 19% increase in effective dose. Image noise increased with lower peak kilovoltage. The measured noise difference was greatest at 80 kVp, absolute increases were less than 2.5 HU. There was no difference in subjective image quality among protocols. Reducing the voltage from 120 to 80 kVp for neck CT can result in greater than 50% reduction in the absorbed organ dose to the bone marrow of the cervical spine and mandible without impairment in subjective image quality.
    American Journal of Roentgenology 03/2012; 198(3):621-7. · 2.90 Impact Factor
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    ABSTRACT: The purpose of this study was to identify an optimal cross-sectional neck diameter that correlates with image quality and radiation exposure in MDCT examinations of the neck performed with automatic tube current modulation. Ninety-six adults underwent 64-MDCT of the neck with automatic tube current modulation at the same noise setting. On frontal and lateral scout images, maximal body diameters were measured in the transverse and anteroposterior planes at two levels: just below the mandible (upper neck) and at the lung apex (lower neck). Neck diameters were correlated with image quality on a subjective 4-point scale and with radiation exposure (volume CT dose index). As continuous variables, both anteroposterior and transverse diameters in the lower neck were associated with image quality (p ≤ 0.0012). Diameters in the upper neck were not associated with image quality. When diameters in the lower neck were categorized into small, medium, and large, image quality grades were higher for smaller patients (p < 0.001). Images of 81% of small patients (lower neck transverse diameter < 40 cm) had a high image quality grade, compared with images of 7-20% of large patients (diameter > 48 cm). Transverse diameter in the lower neck correlated best with radiation dose measured as volume CT dose index (r = 0.78). When transverse diameter in the lower neck was used to categorize patients' size, the mean volume CT dose index for small patients was 34.1 mSv and that for large patients was 63.5 mSv. Lower neck transverse diameter on the CT scout image best correlates with image quality and radiation exposure for neck MDCT examinations performed with automatic tube current modulation. Images of patients with a lower neck transverse diameter less than 40 cm are of higher quality than those of larger patients. Individualized dose reduction techniques therefore may be appropriate for smaller patients.
    American Journal of Roentgenology 11/2011; 197(5):W904-9. · 2.90 Impact Factor
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    ABSTRACT: The purpose of this article is to compare the radiation dose of conventional fluoroscopy-guided lumbar epidural steroid injections (ESIs) and CT fluoroscopy (CTF)-guided lumbar ESI using both clinical data and anthropomorphic phantoms. We performed a retrospective review of dose parameters for 14 conventional fluoroscopy ESI procedures performed by one proceduralist and 42 CTF-guided ESIs performed by three proceduralists (14 each). By use of imaging techniques similar to those for our clinical cohorts, a commercially available anthropomorphic male phantom with metal oxide semiconductor field effect transistor detectors was scanned to obtain absorbed organ doses for conventional fluoroscopy-guided and CTF-guided ESIs. Effective dose (ED) was calculated from measured organ doses. The mean conventional fluoroscopy time for ESI was 37 seconds, and the mean procedural CTF time was 4.7 seconds. Calculated ED for conventional fluoroscopy was 0.85 mSv compared with 0.45 mSv for CTF. The greatest contribution to the radiation dose from CTF-guided ESI came from the planning lumbar spine CT scan, which had an ED of 2.90 mSv when z-axis ranged from L2 to S1. This resulted in a total ED for CTF-guided ESI (lumbar spine CT scan plus CTF) of 3.35 mSv. The ED for the CTF-guided ESI was almost half that of conventional fluoroscopy because of the shorter fluoroscopy time. However, the overall radiation dose for CTF-guided ESIs can be up to four times higher when a full diagnostic lumbar CT scan is performed as part of the procedure. Radiation dose reduction for CTF-guided ESI is best achieved by minimizing the dose from the preliminary planning lumbar spine CT scan.
    American Journal of Roentgenology 10/2011; 197(4):778-82. · 2.90 Impact Factor
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    ABSTRACT: The purpose of this article is to assess whether iopamidol-370 provides superior vascular contrast of the coronaries and depiction of anatomic detail without affecting heart rate and beat-to-beat variability during coronary dual-source MDCT compared with iodixanol-320. In this prospective trial, coronary CT angiography was performed on 60 adult patients using either iopamidol-370 or iodixanol-320. Cohorts were matched by age, habitus, sex, and baseline heart rate, with cohort sizes determined by power analysis. All studies were performed on a dual-source MDCT scanner with retrospective ECG-gating utilizing automatic pitch adjustment. Data assessment focused on heart rate variability during contrast administration statistically evaluated as Student t test comparisons within and between cohorts, coronary contrast-to-noise ratio analysis of the main coronary arteries utilizing Student t test comparisons between cohorts, and coronary branch depiction and distribution analysis in dual-reader consensus decisions between cohorts. Thirty patients matched for age, habitus, sex, and heart rate were evaluated in each cohort. ECG analyses found a statistically significant (p = 0.013) decrease in heart rate during administration of iodixanol-320. Beat-to-beat variations, expressed as coefficient of variation, within and among cohorts were low (coefficient of variation, < 0.05). Contrast-to-noise ratio was significantly increased for iopamidol-370 versus iodixanol-320 (aortic root, p = 0.021; left main, p = 0.032; left anterior descending, p = 0.033; left circumflex, p = 0.039; and right, p = 0.009). Analysis of coronary branch visualization revealed improved depiction for iopamidol-370 compared with iodixanol-320. Iopamidol-370, with its higher iodine concentration, provided greater vascular contrast of the arterial coronary tree and improved depiction of anatomic detail without significantly impacting cardiac heart rate during coronary MDCT imaging, as compared with iodixanol-320.
    American Journal of Roentgenology 09/2011; 197(3):W445-51. · 2.90 Impact Factor
  • Medical Physics 01/2011; 38(6):3407-. · 2.91 Impact Factor
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    ABSTRACT: The aim of this study was to measure the radiation dose of dual-energy and single-energy multidetector computed tomographic (CT) imaging using adult liver, renal, and aortic imaging protocols. Dual-energy CT (DECT) imaging was performed on a conventional 64-detector CT scanner using a software upgrade (Volume Dual Energy) at tube voltages of 140 and 80 kVp (with tube currents of 385 and 675 mA, respectively), with a 0.8-second gantry revolution time in axial mode. Parameters for single-energy CT (SECT) imaging were a tube voltage of 140 kVp, a tube current of 385 mA, a 0.5-second gantry revolution time, helical mode, and pitch of 1.375:1. The volume CT dose index (CTDI(vol)) value displayed on the console for each scan was recorded. Organ doses were measured using metal oxide semiconductor field-effect transistor technology. Effective dose was calculated as the sum of 20 organ doses multiplied by a weighting factor found in International Commission on Radiological Protection Publication 60. Radiation dose saving with virtual noncontrast imaging reconstruction was also determined. The CTDI(vol) values were 49.4 mGy for DECT imaging and 16.2 mGy for SECT imaging. Effective dose ranged from 22.5 to 36.4 mSv for DECT imaging and from 9.4 to 13.8 mSv for SECT imaging. Virtual noncontrast imaging reconstruction reduced the total effective dose of multiphase DECT imaging by 19% to 28%. Using the current Volume Dual Energy software, radiation doses with DECT imaging were higher than those with SECT imaging. Substantial radiation dose savings are possible with DECT imaging if virtual noncontrast imaging reconstruction replaces precontrast imaging.
    Academic radiology 08/2009; 16(11):1400-7. · 2.09 Impact Factor
  • Jenny K Hoang, Santiago Martinez, Lynne M Hurwitz
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    ABSTRACT: OBJECTIVE: The objective of our study was to review expected findings and complications after thoracic endovascular aortic repair on CT angiography (CTA). CONCLUSION: Luminal and extraluminal changes to the thoracic aorta occur after endovascular stent-grafting. The radiologist can facilitate appropriate management by detecting and differentiating expected CTA findings from complications.
    American Journal of Roentgenology 03/2009; 192(2):515-24. · 2.90 Impact Factor
  • Radiology 03/2009; 250(2):604-5. · 6.34 Impact Factor
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    ABSTRACT: The purpose of this study was to assess whether radiation dose savings using a lower peak kilovoltage (kVp) setting, bismuth breast shields, and automatic tube current modulation could be achieved while preserving the image quality of MDCT scans obtained to assess for pulmonary embolus (PE). CT angiography (CTA) examinations were performed to assess for the presence or absence of pulmonary artery emboli using a 64-MDCT scanner with automatic tube current modulation (noise level=10 HU), two kVp settings (120 and 140 kVp), and bismuth breast shields. Absorbed organ doses were measured using anthropomorphic phantoms and metal oxide semiconductor field effect transistor (MOSFET) detectors. Image quality was assessed quantitatively as well as qualitatively in various anatomic sites of the thorax. Using a lower kVp (120 vs 140 kVp) and automatic tube current modulation resulted in a dose savings of 27% to the breast and 47% to the lungs. The use of a lower kVp (120 kVp), automatic tube current modulation, and bismuth shields placed directly on the anterior chest wall reduced absorbed breast and lung doses by 55% and 45%, respectively. Qualitative assessment of the images showed no change in image quality of the lungs and mediastinum when using a lower kVp, bismuth shields, or both. The use of bismuth breast shields together with a lower kVp and automatic tube current modulation will reduce the absorbed radiation dose to the breast and lungs without degradation of image quality to the organs of the thorax for CTA detection of PE.
    American Journal of Roentgenology 02/2009; 192(1):244-53. · 2.90 Impact Factor
  • Jenny K Hoang, Santiago Martinez, Lynne M Hurwitz
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    ABSTRACT: OBJECTIVE: The purpose of this article is to review open thoracic aortic surgical techniques and to describe the range of postoperative findings on CT angiography (CTA). CONCLUSION: An understanding of surgical thoracic aortic procedures will allow appropriate differentiation of normal from abnormal CTA findings on postoperative imaging.
    American Journal of Roentgenology 02/2009; 192(1):W20-7. · 2.90 Impact Factor
  • Jenny K Hoang, Santiago Martinez, Lynne M Hurwitz
    Seminars in roentgenology 02/2009; 44(1):52-62. · 0.70 Impact Factor
  • Jenny K Hoang, Lynne M Hurwitz, Daniel T Boll
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    ABSTRACT: This study sought to extract information on individual patient habitus from scout imaging and to correlate radiograph tube current settings with enhancement of the coronaries as a function of patient profiles for coronary multidetector computed tomography. Fifty patients underwent coronary 64-slice multidetector computed tomography consisting of 2-plane scouts and electrocardiography-gated coronary studies at 64 x 0.625 mm, radiograph voltage of 120 kVp, and radiograph currents of 295 to 788 mA, which were reconstructed during 65%, 75%, and 85% R-R intervals. Patients' weight was recorded. On scout imaging, chest diameters were determined, and circumferences were calculated. To determine whether body weight showed sex-specific characteristics, t test was used. Pearson correlation determined whether cross-sectional measurements reflected female/male body habitus. On coronary imaging, contrast-to-noise ratios (CNRs) of the aorta and the coronaries were calculated. To assess whether CNRs differed throughout the diastolic phase, t test was used. Data triplets of CNRs and the corresponding current and circumference were plotted; CNRs less than 250 Hounsfield unit (HU) were discarded, dissecting lines as 95th percentiles correlating radiograph currents and patients' circumferences were calculated. Female/male weights differed significantly (P = 0.0006); circumferences based on scouts adequately reflected body weight (coefficients, 0.86 male/0.87 female). Homogenous vascular enhancement of the aorta (mean +/- SD, 344.4 +/- 81.8 HU) and the right (292.3 +/- 82.8 HU) and left (285.8 +/- 81.3 HU) coronaries was achieved (P > 0.005). Ninety-fifth percentile cutoffs identified linear relationships between patient's circumference and the minimal adequate radiograph current achieving CNR less than or equal to 250 HU. Scout imaging can be used to determine individual patient habitus; habitus-adjusted minimal radiograph tube current cutoff levels identified in this study ensuring clinically required levels of coronary enhancement can be used for future coronary CT angiography optimization of tube current based on scout imaging.
    Journal of computer assisted tomography 01/2009; 33(4):498-504. · 1.38 Impact Factor