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| 2. |
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| 3. |
- Wikström, Johan, et al.
(författare)
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Abdominal vessel enhancement with an ultrasmall, superparamagnetic iron oxide blood pool agent : evaluation of dose and echo time dependence at different field strengths
- 1999
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Ingår i: Academic Radiology. - 1076-6332 .- 1878-4046. ; 6:5, s. 292-298
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: The purpose of the study was to determine the dose and echo time dependence of abdominal vessel enhancement at magnetic resonance (MR) imaging after injection of a blood pool contrast agent at two field strengths. MATERIALS AND METHODS: Sixteen healthy volunteers received NC100150 Injection at three dose levels (1.0 mg, 2.5 mg, and 4.0 mg of iron per kilogram of body weight). Images of the aorta and inferior vena cava (IVC) were obtained at 0.5 or 1.5 T. Four sequences with varying echo times were used with each subject. Signal intensities were recorded from the aorta, IVC, vessel vicinity, air, and a marker outside the patient. Contrast-to-noise ratios (CNRs) were calculated for the vessels. Aortic delineation was subjectively evaluated. RESULTS: Images with the highest mean vessel signal intensities, subjectively assessed as satisfactory for aortic delineation, were obtained with 2.5-4.0 mg of iron per kilogram of body weight at both field strengths. The highest CNR was found with 4.0 mg of iron per kilogram of body weight at 1.5 T. An increase in echo time caused larger signal intensity loss at larger dose levels. The signal intensity from the IVC was higher than that of the aorta at all dose levels, echo times, and field strengths. CONCLUSION: NC100150 Injection is an efficient T1-reducing agent at both 0.5 and 1.5 T. A positive dose response for CNR of the aorta and IVC was seen at 1.5 T.
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| 4. |
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| 5. |
- Bornefalk, Hans
(författare)
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Estimation and Comparison of CAD System Performance in Clinical Settings
- 2005
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Ingår i: Academic Radiology. - : Elsevier BV. - 1076-6332 .- 1878-4046. ; 12:6, s. 687-694
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives. Computer-aided detection (CAD) systems are frequently compared using free-response receiver operating characteristic (FROC) curves. While there are ample statistical methods for comparing FROC curves, when one is interested in comparing the outcomes of 2 CAD systems applied in a typical clinical setting, there is the additional matter of correctly determining the system operating point. This article shows how the effect of the sampling error on determining the correct CAD operating point can be captured. By incorporating this uncertainty, a method is presented that allows estimation of the probability with which a particular CAD system performs better than another on unseen data in a clinical setting. Materials and Methods. The distribution of possible clinical outcomes from 2 artificial CAD systems with different FROC curves is examined. The sampling error is captured by the distribution of possible system thresholds of the classifying machine that yields a specified sensitivity. After introducing a measure of superiority, the probability of one system being superior to the other can be determined. Results. It is shown that for 2 typical mammography CAD systems, each trained on independent representative datasets of 100 cases, the FROC curves must be separated by 0.20 false positives per image in order to conclude that there is a 90% probability that one is better than the other in a clinical setting. Also, there is no apparent gain in increasing the size of the training set beyond 100 cases. Discussion. CAD systems for mammography are modeled for illustrative purposes, but the method presented is applicable to any computer-aided detection system evaluated with FROC curves. The presented method is designed to construct confidence intervals around possible clinical outcomes and to assess the importance of training set size and separation between FROC curves of systems trained on different datasets.
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| 6. |
- Cagnoli, Patricia, et al.
(författare)
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Reduced Insular Glutamine and N-Acetylaspartate in Systemic Lupus Erythematosus: A Single-Voxel H-1-MR Spectroscopy Study
- 2013
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 20:10, s. 1286-1296
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: To investigate for differences in metabolic concentrations and ratios between patients with systemic lupus erythematosus (SLE) without (group SLE) and those with neurological symptoms (group NPSLE) compared to a healthy control (group HC) in three normal-appearing brain regions: the frontal white matter, right insula (RI), and occipital gray matter and whether changes in any of the metabolites or metabolic ratios are correlated to disease activity and other clinical parameters. Materials and Methods: Twenty patients with SLE (18 women and 2 men, age range 23.4-64.6 years, mean age 43.9 years), 23 NPSLE patients (23 women, age range 23.7-69.8 years, mean age 42.4 years), and 21 HC (19 women and 2 men, age range 21.0-65.7 years, mean age 43.4 years) were included. All subjects had conventional brain magnetic resonance imaging and H-1 single-voxel spectroscopy, clinical assessment, and laboratory testing. Results: NPSLE patients had significantly reduced N-acetylaspartate (NAA)/creatine compared to HC (P = .02) and SLE patients (P = .01) in the RI. Lower glutamine/creatine levels were also detected in RI in both patient groups and in frontal white matter in NPSLE patients compared to HC (P = .01, P = .02). NAA/Cr ratio in the RI was significantly negatively correlated with the Systemic Lupus Erythematosus Disease Activity Index (r = -0.41; P = .008), and patients with active SLE symptoms also had a trend toward lower NAA/creatine ratios (1.02 vs 1.12; P = .07). Conclusions: The present data support previous findings of abnormal metabolic changes in normal-appearing regions in the brain of both SLE and NPSLE patients and raise the possibility that especially NAA, glutamine, and glutamate may be additional biomarkers for cerebral disease activity in SLE patients as these early metabolic changes occur in the brain of SLE patients before neurologic and imaging manifestations become apparent.
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| 7. |
- Chai, Chun-Ming, et al.
(författare)
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Signs in Vector-Electrocardiography (VECG) Predicting the Fibrillatory Propensity of Iodixanol and Mannitol Solutions After Injection Into the Left Coronary Artery of Pigs.
- 2007
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 14:2, s. 162-177
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives. To find signs in vector-electrocardiography (VECG) predicting the ventricular fibrillatory propensity (VF-PROP) of iodixanol and mannitol solutions after injection into the left coronary artery (LCA) of pigs. Materials and Methods. Five plasma-isotonic solutions perfused LCA: lod 320 + Na/Ca (iodixanol 320 mg I/mL, 19 mM NaCl, 0.3 mM CaCl2), lod 320 + Mann (iodixanol 320 mg I/mL, 50 mM mannitol), Mann + Na/Ca (240 mM mannitol, 19 mM NaCl, 0.3 mM CaCl2) Mann (275 mM mannitol), and Ringer (representing "physiologic electrolytes"). The first two solutions have at 37 degrees C viscosity 13 mPas and the others <1 mPas. In eight pigs, 20 mL of each solution was injected twice for 10 seconds, and in 15 pigs, each solution was injected for 11-40 seconds (0.5 mL/second) through a wedged catheter in the LCA. If ventricular fibrillation (VF) occurred, injection was stopped and heart was defibrillated. If VF did not occur, perfusion period was 40 seconds. A higher frequency of VF and a shorter period from start of injection until start of VF gave a solution a higher ranking of VF-PROP. Results. The 10-second injections caused no VF. Ringer and lod 320 + Na/Ca caused no VF after 40-second injections, whereas the other solutions caused VF. Ranking the solutions from lowest to highest VF-PROP gave: Ringer = lod 320 + Na/Ca < lod 320 + Mann < Mann + Na/Ca < Mann. Prolongation of QRS time and QTc time were the only VECG signs that showed significant differences (P <.05) between all solutions and correctly ranked the VF-PROP of all solutions in both animal groups. Conclusion. The results fit with the concept that a more physiologic electrolyte composition and a higher viscosity of a test solution will, after start of injection of that solution into LCA, delay changes in the electrolyte composition in myocardial interstitial fluid and also delay start of VF. If a plasma isotonic contrast medium (CM) with lower viscosity than that of iodixanol at 320 mgI/mL were created, we conclude that such a CM should have electrolyte composition closer to that of Ringer than present composition (19 mM NaCl and 0.3 mM CaCl2) to counteract the effects of faster diffusion of nonphysiologic electrolyte composition from the low-viscosity CM to myocardial interstitial fluid.
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| 8. |
- Diaz, Sandra, et al.
(författare)
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Progression of Emphysema in a 12-month Hyperpolarized (3)He-MRI Study Lacunarity Analysis Provided a More Sensitive Measure than Standard ADC Analysis(1).
- 2009
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 16:6, s. 700-707
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: Inhaled hyperpolarized (3)He magnetic resonance (MR) imaging has been used to measure alveolar size in patients with emphysema. The aim of this study was to test the hypothesis that (3)He MR images could be used to develop a biomarker of emphysema progression. MATERIALS AND METHODS: Twelve healthy controls and 18 patients with emphysema (eight current smokers, 10 ex-smokers) were imaged at baseline and 6 and 12 months. An additional nine subjects with alpha-1 antitrypsin deficiency (four with emphysema, six without symptoms) were also imaged at baseline and at 6 months. Each subject was imaged at two lung volumes: functional residual capacity (FRC) and FRC plus 15% of total lung capacity. Means and standard deviations of apparent diffusion coefficients (ADCs) were calculated from coronal images of the entire lung and correlated with pulmonary function test results. The lacunarity hypothesis was tested and calculated from the data using a range of 2x2 x 2 to 6x6 x 6 voxels, and the average was calculated. RESULTS: There was no change in the mean ADC at either lung volume in any subject over the 6- or 12-month period. FRC and residual volume increased over the 12 months, suggesting air trapping. The lacunarity of images collected at FRC increased at 6 and 12 months in smokers only (P=.063 and P=.023, respectively). CONCLUSIONS: The mean ADC calculated from MR images of the lungs with helium was not sufficiently sensitive to detect changes over a 12-month period. However, lacunarity captured more of the spatial information in the images and detected emphysema progress in the smokers.
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| 9. |
- Elias, Augusto E., et al.
(författare)
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MR Spectroscopy Using Normalized and Non-normalized Metabolite Ratios for Differentiating Recurrent Brain Tumor from Radiation Injury
- 2011
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 18:9, s. 1101-1108
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: To compare the ability of normalized versus non-normalized metabolite ratios to differentiate recurrent brain tumor from radiation injury using magnetic resonance spectroscopy (MRS) in previously treated patients. Materials and Methods: Twenty-five patients with previous diagnosis of primary intracranial neoplasm confirmed with biopsy/resection, previously treated with radiation therapy (range, 54-70 Gy) with or without chemotherapy and new contrast enhancing lesion on a 1.5 T magnetic resonance imaging at the site of the primary neoplasm participated in this retrospective study. After MRS, clinical, radiological, and histopathology data were used to classify new contrast-enhancing lesions as either recurrent neoplasm or radiation injury. Volume of interest included both the lesion and normal-appearing brain on the contralateral side. Non-normalized metabolic ratios were calculated from choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) spectroscopic values obtained within the contrast-enhancing lesion: Cho/Cr, NAA/Cr, and Cho/NAA. Normalized ratios were calculated using the metabolic values from the contralateral normal side: Cho/normal creatinine (nCr), Cho/normal N-acetylaspartate (nNAA), Cho/normal choline, NAA/nNAA, NAA/nCr, and Cr/nCr. Results were correlated with the final diagnosis by Wilcoxon rank-sum analysis. Results: Two of three non-normalized ratios, Cho/NAA (sensitivity 86%, specificity 90%) and NAA/Cr (sensitivity 93%, specificity 70%) significantly associated with tumor recurrence even after correcting for multiple comparisons. Of the six normalized ratios, only Cho/nNAA significantly correlated with tumor recurrence (sensitivity 73%, specificity 40%), but did not remain significant after correcting for multiple comparisons. Conclusion: Cho/NAA and NAA/Cr were the two ratios with the best discriminating ability and both had better discriminating ability than their corresponding normalized ratios (Area under the curve = 0.92 versus 0.77, AUC= 0.85 vs. 0.66), respectively.
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| 11. |
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| 12. |
- Hedner, Charlotta, et al.
(författare)
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Associations between Presence of Relevant Information in Referrals to Radiology and Prevalence Rates in Patients with Suspected Pulmonary Embolism.
- 2013
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 20:9, s. 1115-1121
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to assess if the presence of information including the pretest probability (Wells score), other known risk factors, and symptoms given on referrals for computed tomography (CT) pulmonary angiography correlated with prevalence rates for pulmonary embolism (PE). Also, to evaluate for differences between a university and a regional hospital setting regarding patient characteristics, amount of relevant information provided on referrals, and prevalence rates for pulmonary embolism.
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| 13. |
- Jensen, Kristin, et al.
(författare)
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Quantitative Measurements Versus Receiver Operating Characteristics and Visual Grading Regression in CT Images Reconstructed with Iterative Reconstruction : A Phantom Study
- 2018
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Ingår i: Academic Radiology. - : ELSEVIER SCIENCE INC. - 1076-6332 .- 1878-4046. ; 25:4, s. 509-518
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: This study aimed to evaluate the correlation of quantitative measurements with visual grading regression (VGR) and receiver operating characteristics (ROC) analysis in computed tomography (CT) images reconstructed with iterative reconstruction. Materials and Methods: CT scans on a liver phantom were performed on CT scanners from GE, Philips, and Toshiba at three dose levels. Images were reconstructed with filtered back projection (FBP) and hybrid iterative techniques (ASiR, iDose, and AIDR 3D of different strengths). Images were visually assessed by five readers using a four- and five-grade ordinal scale for liver low contrast lesions and for 10 image quality criteria. The results were analyzed with ROC and VGR. Standard deviation, signal-to-noise ratios, and contrast to-noise ratios were measured in the images. Results: All data were compared to FBP. The results of the quantitative measurements were improved for all algorithms. ROC analysis showed improved lesion detection with ASiR and AIDR and decreased lesion detection with iDose. VGR found improved noise properties for all algorithms, increased sharpness with iDose and AIDR, and decreased artifacts from the spine with AIDR, whereas iDose increased the artifacts from the spine. The contrast in the spine decreased with ASiR and iDose. Conclusions: Improved quantitative measurements in images reconstructed with iterative reconstruction compared to FBP are not equivalent to improved diagnostic image accuracy.
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| 14. |
- Lidegran, Marika, et al.
(författare)
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Cranial CT for diagnosis of intracranial complications in adult and pediatric patients during ECMO : Clinical benefits in diagnosis and treatment
- 2007
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Ingår i: Academic Radiology. - Netherlands : Elsevier BV. - 1076-6332 .- 1878-4046. ; 14:1, s. 62-71
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: To evaluate the clinical utility of cranial computed tomography (CT) in pediatric and adult patients during ongoing extracorporeal membrane oxygenation (ECMO) treatment from acute respiratory failure and to assess the frequency of intracranial hemorrhage (ICH) and infarction during the treatment. MATERIALS AND METHODS: The medical records of 123 consecutive patients, 54 children (ages 3 months-17 years) and 69 adults (ages 18-62 years), treated with ECMO over a 10-year period were searched for cranial CT performed during ECMO. Indications for CT, CT findings, impact on clinical management, and patient outcome were noted. In addition, all CT scans were reviewed for the frequency of ICH or infarction. RESULTS: Seventy-eight patients had cranial CT while on ECMO. ICH or cerebral infarction were detected in 45 (37%) of the 123 patients. Eighteen patients (15%) had focal hemorrhage, 11 (9%) focal infarction, and 16 (13%) general brain edema. In 16 of the 45 patients, the CT findings were decisive to withdraw the ECMO treatment. Five patients were weaned from ECMO, and in four patients the findings motivated cranial surgery during ECMO. In the remaining 20 patients with less extended intracranial pathology, the ECMO treatment was continued with high survival. CONCLUSION: Cranial CT has an important role during ECMO treatment to reveal or exclude severe intracranial complications where ECMO treatment should be discontinued. Less severe complications have a favorable prognosis with continued treatment. Our study suggests an underreporting of intracranial complications in adults and pediatric patients on ECMO because of low utilization of neuroimaging.
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| 15. |
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| 16. |
- Masch, William R, et al.
(författare)
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Comparison of Diffusion Tensor Imaging and Magnetic Resonance Perfusion Imaging in Differentiating Recurrent Brain Neoplasm From Radiation Necrosis
- 2016
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 23:5, s. 569-576
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: To compare differences in diffusion tensor imaging (DTI) and dynamic susceptibility-weighted contrast-enhanced (DSC) magnetic resonance (MR) perfusion imaging characteristics of recurrent neoplasm and radiation necrosis in patients with brain tumors previously treated with radiotherapy with or without surgery and chemotherapy. MATERIALS AND METHODS: Patients with a history of brain neoplasm previously treated with radiotherapy with or without chemotherapy and surgery who developed a new enhancing lesion on posttreatment surveillance MRI were enrolled. DSC perfusion MRI and DTI were performed. Region of interest cursors were manually drawn in the contrast-enhancing lesions, in the perilesional white matter edema, and in the contralateral normal-appearing frontal lobe white matter. DTI and DSC perfusion MR indices were compared in recurrent tumor versus radiation necrosis. RESULTS: Twenty-two patients with 24 lesions were included. Sixteen (67%) lesions were placed into the recurrent neoplasm group and eight (33%) lesions were placed into the radiation necrosis group using biopsy results as the gold standard in all but three patients. Mean apparent diffusion coefficient values, mean parallel eigenvalues, and mean perpendicular eigenvalues in the contrast-enhancing lesion were significantly lower, and relative cerebral blood volume was significantly higher for the recurrent neoplasm group compared to the radiation necrosis group (P < 0.01, P = 0.03, P < 0.01, and P < 0.01, respectively). CONCLUSIONS: The combined assessment of DTI and DSC MR perfusion properties of new contrast-enhancing lesions is helpful in distinguishing recurrent neoplasm from radiation necrosis in patients with a history of brain neoplasm previously treated with radiotherapy with or without surgery and chemotherapy.
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| 17. |
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| 18. |
- Rohrbach, Daniel J., et al.
(författare)
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Preoperative Mapping of Nonmelanoma Skin Cancer Using Spatial Frequency Domain and Ultrasound Imaging
- 2014
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Ingår i: Academic Radiology. - : Elsevier. - 1076-6332 .- 1878-4046. ; 21:2, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and ObjectivesThe treatment of nonmelanoma skin cancer (NMSC) is usually by surgical excision or Mohs micrographic surgery and alternatively may include photodynamic therapy (PDT). To guide surgery and to optimize PDT, information about the tumor structure, optical parameters, and vasculature is desired.Materials and MethodsSpatial frequency domain imaging (SFDI) can map optical absorption, scattering, and fluorescence parameters that can enhance tumor contrast and quantify light and photosensitizer dose. High frequency ultrasound (HFUS) imaging can provide high-resolution tumor structure and depth, which is useful for both surgery and PDT planning.ResultsHere, we present preliminary results from our recently developed clinical instrument for patients with NMSC. We quantified optical absorption and scattering, blood oxygen saturation (StO2), and total hemoglobin concentration (THC) with SFDI and lesion thickness with ultrasound. These results were compared to histological thickness of excised tumor sections.ConclusionsSFDI quantified optical parameters with high precision, and multiwavelength analysis enabled 2D mappings of tissue StO2 and THC. HFUS quantified tumor thickness that correlated well with histology. The results demonstrate the feasibility of the instrument for noninvasive mapping of optical, physiological, and ultrasound contrasts in human skin tumors for surgery guidance and therapy planning.
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| 19. |
- Sundgren, Pia
(författare)
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Mentoring Radiology Residents in Clinical and Translational Research.
- 2012
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 19:9, s. 1110-1113
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Tidskriftsartikel (refereegranskat)abstract
- To be an effective mentor at any level is always a challenge and requires a dedication to teaching and mentorship and being prepared to devote a significant proportion of one's time. But if you are open-minded and deeply care for your mentee, you have the opportunity to be a successful mentor. This presentation is based on personal experience of mentoring radiology residents, doctoral students, and post doctoral students for several years.
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| 20. |
- Söderman, Christina, et al.
(författare)
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Detection of Pulmonary Nodule Growth with Chest Tomosynthesis: A Human Observer Study Using Simulated Nodules
- 2019
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Ingår i: Academic Radiology. - : Elsevier BV. - 1076-6332 .- 1878-4046. ; 26:4, s. 508-518
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Tidskriftsartikel (refereegranskat)abstract
- Chest tomosynthesis has been suggested as a suitable alternative to CT for follow-up of pulmonary nodules. The aim of the present study was to investigate the possibility of detecting pulmonary nodule growth using chest tomosynthesis. Materials and Methods: Simulated nodules with volumes of approximately 100 mm 3 and 300 mm 3 as well as additional versions with increasing volumes were created. The nodules were inserted into images from pairs of chest tomosynthesis examinations, simulating cases where the nodule had either remained stable in size or increased in size between the two imaging occasions. Nodule volume growths ranging from 11% to 252% were included. A simulated dose reduction was applied to a subset of the cases. Cases differing in terms of nodule size, dose level, and nodule position relative to the plane of image reconstruction were included. Observers rated their confidence that the nodules were stable in size or not. The rating data for the nodules that were stable in size was compared to the rating data for the nodules simulated to have increased in size using ROC analysis. Results: Area under the curve values ranging from 0.65 to 1 were found. The lowest area under the curve values were found when there was a mismatch in nodule position relative to the reconstructed image plane between the two examinations. Nodule size and dose level affected the results. Conclusion: The study indicates that chest tomosynthesis can be used to detect pulmonary nodule growth. Nodule size, dose level, and mismatch in position relative to the image reconstruction plane in the baseline and follow-up examination may affect the precision.
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| 23. |
- Vikgren, Jenny, 1957, et al.
(författare)
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Visual and Quantitative Evaluation of Emphysema: A Case-Control Study of 1111 Participants in the Pilot Swedish CArdioPulmonary BioImage Study (SCAPIS)
- 2020
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Ingår i: Academic Radiology. - : Elsevier BV. - 1076-6332 .- 1878-4046. ; 27:5, s. 636-643
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: Emphysema is a hallmark of chronic obstructive pulmonary disease. The primary aim of this study was to investigate inter- and intraobserver agreement of visual assessment of mild emphysema in low-dose multidetector computed tomography of subjects in the pilot SCAPIS in order to certify consistent detection of mild emphysema. The secondary aim was to investigate the performance of quantitative densitometric measurements in the cohort. Materials and Methods: Participants with emphysema (n = 100, 56 males and 44 females) reported in the electronic case report form of pilot SCAPIS and 100 matched controls (gender, age, height, and weight) without emphysema were included. To assess interobserver variability the randomized examinations were evaluated by two thoracic radiologists. For intraobserver variability three radiologists re-evaluated randomized examinations which they originally evaluated. The results were evaluated statistically by Krippendorff's α. The dataset was also assessed quantitively for % lung attenuation value −950 HU (LAV950), mean lung density and total lung volume by commercially available software. Results: Emphysema was visually scored as mild and Krippendorff's α was ≥0.8 for both the inter- and intraobserver agreement regarding presence of emphysema and approaching 0.8 regarding presence and extent of emphysema by location in the upper lobes. Mean LAV950 was not different between the emphysematous and the nonemphysematous participants; 8.3% and 8.4%, respectively. Conclusion: The inter- and intraobserver agreement for visual detection of mild emphysema in low-dose multidetector computed tomography was good. Surprisingly, quantitative analysis could not reliably identify participants with mild emphysema, which hampers the use of automatic evaluation. © 2019 The Association of University Radiologists
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| 24. |
- Wang, Page I., et al.
(författare)
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Perfusion-weighted MR Imaging in Cerebral Lupus Erythematosus
- 2012
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 19:8, s. 965-970
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objective: Neuropsychiatric systemic lupus erythematosus (NPSLE) is a diagnostically challenging, severe, and life-threatening condition, which is currently lacking a "gold standard." Our aim with this study is to look for magnetic resonance (MR) perfusion differences in NPSLE, SLE, and healthy control (HC) patients and correlate our findings with clinical parameters. Materials and Methods: Twenty-four NPSLE patients, 21 SLE patients, and 21 HC underwent dynamic susceptibility contrast enhanced MR perfusion using a 3-T scanner. Nine prospectively selected intracranial regions of interest were placed in white and gray matter and the cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MU) values were calculated. Subjects underwent clinical evaluation with SLEDAI and serum antibodies. Results: The SLE patients had higher CBF and CBV compared to the HC overall (P =.01) and in specific areas (P =.03-.048). SLE patients with signs of active disease (elevated SLEDAI and anti-double-stranded DNA) had significantly elevated CBV, CBF, and MU in the posterior cingulate gyrus (P =.01-.02). No significant difference was seen in the magnetic resonance perfusion measurements of NPSLE patients compared to SLE and HC, although the NPSLE patients also showed higher CBV variability compared to the SLE (P =.0004) and HC cohort (P <.0001). Conclusion: SLE patients have increased CBV and CBF compared to healthy controls. The SLE patients with clinical markers for active disease have elevated CBV, CBF, and MU in the posterior cingulate gyrus. NPSLE patients show increased variability in perfusion measurements, which may explain why susceptibility contrast enhanced MRI has not yet provided a specific target for NPSLE.
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| 25. |
- Zakhary, Mina M., et al.
(författare)
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Prevalence and Etiology of Intracranial Hemorrhage in Term Children Under the Age of Two Years: A Retrospective Study of Computerized Tomographic Imaging and Clinical Outcome in 798 Children
- 2009
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 16:5, s. 572-577
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives. The purposes of this study were to retrospectively identify various etiologies underlying intracranial hemorrhages (ICHs) in term infants aged <2 years and their respective prevalence in this population and to describe the long-term clinical outcomes in these patients. Materials and Methods. A retrospective review of the medical records and computed tomographic studies of the head in 798 term infants aged 0 to 24 months with suspected or known ICHs was conducted. Results. ICHs were present in 195 of the 798 infants (24%). More than one type of ICH was present in 32%. Subdural hemorrhage was the most frequent type of ICH, occurring in 63% of the infants. Good clinical outcomes were present in 49% of the infants but varied depending on the location, etiology, and timing of the ICH. Conclusion. The incidence of various etiologies of ICH depended on the ages of the infants. The overall clinical outcomes were good, with no long-term sequelae in half of the infants presenting with ICHs. In infants aged >4 weeks presenting with ICHs, special attention should be given to the possibility of nonaccidental trauma etiology, because this is common and has worse long-term outcomes.
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| 34. |
- Stenström, Mats, et al.
(författare)
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Methodologic aspects of computed microtomography to monitor the development of osteoporosis in gastrectomized rats
- 1995
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Ingår i: Academic Radiology. - 1076-6332. ; 2:9, s. 785-791
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives We investigated the methodologic development of computed microtomography (CMT) for monitoring the development of osteoporosis in male Sprague-Dawley rats. Methods Eight rats were gastrectomized and eight rats were sham operated. Femurs, tibias, and tails were prepared, and CMT scans with spatial resolutions of 5–500 μm were made. Bone diameters, bone areas, and moments of inertia were determined from the CMT scans. Optimal slice position and the need for spatial resolution and energy optimization for future in vivo applications were investigated. Results Gastrectomy caused dramatic changes in the bone architecture of the tibia and the femur. The main features were vacuolization of the bone and reduced amounts of compact bone. Although the outer diameters of tubular bones (femur and tibia) were largely unaffected, their inner diameters were greatly increased following gastrectomy. Relative bone area and moment of inertia were greatly reduced. The optimal photon energy was 12 keV. Conclusion It is possible to monitor gastrectomy-evoked changes in bone morphology at various sites in rats using CMT scanning. The changes are suggestive of osteoporosis. By optimizing the energy spectrum and spatial resolution, as well as choosing the proper slice position, it should be possible to keep absorbed doses low enough to avoid acute radiation injury in repeated in vivo measurements.
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| 39. |
- Au, Lauren E., et al.
(författare)
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Post-Healthy, Hunger-Free Kids Act Adherence to Select School Nutrition Standards by Region and Poverty Level : The Healthy Communities Study
- 2020
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Ingår i: Journal of nutrition education and behavior. - : Elsevier BV. - 1499-4046 .- 1878-2620. ; 52:3, s. 249-258
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study determined the extent to which schools adhered to select nutrition and wellness provisions of the 2010 Healthy, Hunger-Free Kids Act and examined differences by US region and school poverty level. Design: Comparison of cross-sectional observational data from the Healthy Communities Study (2013-2015) by region and school poverty level. Participants: A total of 401 US elementary and middle schools. Main Outcome Measures: Adherence with federal nutrition standards for meals and competitive foods; extent of implementation of select aspects of school wellness policies. Analysis: Descriptive statistics and multivariate regression were used. Differences were examined by school poverty level and region, adjusting for other school- and community-level covariates. Results: Most schools reported meeting reimbursable school meal nutrition standards (74%); more schools in the West met nutrition standards (82%) than in the Midwest (64%). Most grains offered at lunch were whole grain-rich (82%), and most competitive foods complied with standards (78%) before they were required. Most schools had a wellness coordinator (80%). Lowest levels of adherence were reported for guidelines for classroom or school event foods. No differences were observed by school poverty level. Conclusions and Implications: Findings suggest that Healthy Hunger-Free Kids Act provisions were feasible across a wide variety of schools, and schools successfully implemented reimbursable school meal nutrition standards regardless of school poverty level.
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| 40. |
- Blane, Caroline E, et al.
(författare)
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Decreasing rate of fatty involution at screening mammography
- 2002
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Ingår i: Academic Radiology. - 1878-4046. ; 9:8, s. 895-898
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: This study was performed to document the perceived decrease in fatty involution at screening mammography during the past decade and evaluate the influence of hormone replacement therapy (HRT). MATERIALS AND METHODS: In December 1996, the mammograms of 261 consecutive screening patients with a comparison study obtained 5 years earlier were evaluated, and their breasts were categorized according to Breast Imaging Reporting and Data System categories for breast density. The women, aged 50-59 years, included 119 who had been receiving HRT for 0.25-15 years (mean, 3 years). From the files, 261 age-matched screening mammograms from 1986 were obtained; these patients also had comparison mammograms from 1981. Analysis of variance was used to determine differences between the 1980s group, the 1990s group receiving HRT, and the 1990s group not receiving HRT. Scheffe tests were used for post hoc comparisons. Stepwise regression analysis was used to evaluate the relative influence of age, decade, score of the first mammogram, and HRT. RESULTS: Breast density for the 1991 mammograms did not differ significantly from that in 1981 (P < .05). Initial breast density was the best predictor of final breast density in both decades (P < .001), regardless of HRT status. The change in breast density (toward fatty) over the 5-year interval in the 1980s (mean, 0.48) was significantly greater than that in both 1990s groups (mean for HRT group, 0.11; no HRT, 0.30; P < .05). CONCLUSION: These results confirm that breast density at screening mammography in the 1990s did not decrease with age at the same rate as in the 1980s, even in patients not receiving HRT.
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| 41. |
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| 45. |
- Dapi Nzefa, Léonie, 1971-, et al.
(författare)
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"I eat to be happy, to be strong, and to live." perceptions of rural and urban adolescents in Cameroon, Africa.
- 2007
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Ingår i: Journal of nutrition education and behavior. - US : Elsevier. - 1499-4046 .- 1878-2620. ; 39:6, s. 320-326
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate factors influencing rural and urban adolescents' food perceptions during a time of nutritional transition in Cameroon, Africa.DESIGN: Qualitative in-depth interviews.SETTINGS: Yaoundé urban and Bandja rural areas.PARTICIPANTS: Fifteen adolescents 12 to 15 years old purposely selected from schools in urban and rural areas.ANALYSIS: Interviews were audiotaped, transcribed, and analyzed using Grounded Theory method.FINDINGS: Factors influencing adolescents' food perceptions from the rural area were "to live" "health" and "poverty." Among adolescents from the urban poor area, "health," "beauty," and "not enough money" were factors. Among adolescents from the urban rich area, "pleasure" and "beauty" were factors. Rural girls liked "to be fat," whereas girls from the urban poor wanted "to be a little bit fat," and girls from the urban rich wanted "to be normal."CONCLUSIONS AND IMPLICATIONS: Food behavior is changing from a diet composed of traditional food in rural areas to a more westernized diet in urban areas. The relationship between socioeconomic factors and nutrition needs to be examined with a sufficiently large number of adolescents to investigate these factors in a quantitative survey. Healthful local food should be available at home and from vendors. Nutrition education about food and diet-related diseases is needed in school.
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| 46. |
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| 47. |
- Frennby, Bo, et al.
(författare)
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Clearance of iohexol, chromium-51-ethylenediaminetetraacetic acid, and creatinine for determining the glomerular filtration rate in pigs with normal renal function: comparison of different clearance techniques
- 1996
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Ingår i: Academic Radiology. - 1878-4046. ; 3:8, s. 651-659
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: We wanted to improve determination of the glomerular filtration rate (GFR) with plasma clearance techniques because the alternative-renal clearance techniques-may involve inaccurate urine sampling or risk of urinary tract infection when bladder catheterization becomes necessary. Therefore, we compared the renal and plasma clearances of iohexol and chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), as well as endogenous creatinine clearance, in 19 normal pigs using different techniques. METHODS: After an intravenous bolus injection of the GFR markers, 16 plasma samples were used to plot the marker concentrations versus time for 4.5 hr. Urine was collected during nine 30-min periods. Plasma clearance was calculated by dividing the dose of marker with the area under the plasma concentration curve (AUC) from the time of injection to infinity using one-compartment (ClAUC-slope) and three-compartment (ClAUC-3comp) models. The renal clearance was calculated by dividing the amount of marker excreted in the urine in a period with the AUC in the same period. This AUC was determined by integrating the total area in the period (Clren adv)--our reference method representing the "true" GFR--or by using the arithmetic mean of the plasma concentrations of the marker at the beginning and end of the urine collection period (Clren simple). Creatinine clearance was determined according to Clren simple. RESULTS: Renal clearances of iohexol and 51Cr-EDTA were significantly higher than creatinine clearance (P = .0002). There was no significant difference between the renal clearances of iohexol and 51Cr-EDTA or between their plasma clearances. The two mathematical methods of calculating the renal clearance of iohexol were highly correlated (rs = .99), as were the two methods of calculating its plasma clearance (rs = .95). Because of the extrarenal clearance of the markers, the plasma clearance methods for iohexol and 51Cr-EDTA always overestimated the true GFR. ClAUC-3comp was the method closest to the true GFR. For iohexol, the median overestimation of the GFR was higher with ClAUC-slope when early plasma samples (30-120 min) after injection of the marker were used (5.5 ml.min-1.10 kg-1) than when late samples (180-270 min) were used (4.0 ml.min-1.10 kg-1). After subtracting the median extrarenal clearances of iohexol and 51Cr-EDTA (previously determined in nephrectomized pigs) from their plasma clearances (ClAUC-3comp), the median overestimation of the true GFR was reduced from 2.0 to 1.1 ml.min-1.10 kg-1 with iohexol and from 2.1 to 1.3 ml.min-1.10 kg-1 with 51Cr-EDTA. CONCLUSION: GFR determination with plasma clearance techniques can be improved in three- and one-compartment models by taking late plasma samples and by subtracting the extrarenal plasma clearance of the species. One-compartment models can be improved by determining a correction formula in the species for the early parts of the decay curve of the plasma concentration of the marker
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| 48. |
- Frennby, Bo, et al.
(författare)
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Extrarenal plasma clearance of iohexol, chromium-51-ethylenediaminetetraacetic acid, and inulin in anephric pigs
- 1996
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Ingår i: Academic Radiology. - 1878-4046. ; 3:2, s. 145-153
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: To improve the measurement of the glomerular filtration rate (GFR), we determined the extrarenal plasma clearance of the GFR markers iohexol, chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), and inulin using 11 anephric pigs. METHODS: After an intravenous (i.v.) bolus injection of the markers, the decay curves of their plasma concentrations were monitored for 29 hr by 16 plasma samples. The area under the curve (AUC; concentration of marker versus time) was calculated according to one- and three-compartment kinetics. The extrarenal clearance was calculated by dividing the dose of marker by the AUC. RESULTS: In the three-compartment model, the median of the extrarenal clearances of iohexol, 51Cr-EDTA, and inulin were 0.87 ml.min-1.10 kg-1 (range = 0.62-1.26 ml.min-1.10 kg-1), 0.79 ml.min-1.10 kg-1 (range = 0.61-1.04 ml.min-1.10 kg-1), and 0.83 ml.min-1.10 kg-1 (range = 0.65-1.17 ml.min-1.10 kg-1). The extrarenal clearance of 51Cr-EDTA was slightly lower than that of iohexol and inulin when measured with the three-compartment model (p = .015). There was no statistically significant difference between the two models of kinetics in calculating clearance of the same marker. CONCLUSION: Our results indicate that subtracting the median values of the extrarenal clearance of the markers from the total plasma clearance will provide GFR values closer to the "true" GFR. This technique might prove useful in GFR calculations in patients with a very low GFR (e.g., residual GFR in patients on dialysis)
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| 49. |
- Golman, Klaes, et al.
(författare)
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13C-angiography.
- 2002
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Ingår i: Academic Radiology. - 1878-4046. ; 9:Suppl 2, s. 507-510
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Tidskriftsartikel (refereegranskat)
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| 50. |
- Golman, Klaes, et al.
(författare)
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Overhauser-enhanced MRI.
- 2002
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Ingår i: Academic Radiology. - 1878-4046. ; 9 Suppl 1, s. 104-108
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Tidskriftsartikel (refereegranskat)
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