| 1. |
- Blomqvist, L
(author)
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Colorectal cancer imaging
- 2004
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In: AJR. American journal of roentgenology. - : American Roentgen Ray Society. - 0361-803X .- 1546-3141. ; 182:6, s. 1600-1601
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Journal article (other academic/artistic)
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| 2. |
- Dahlman, Pär, et al.
(author)
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How Much Dose Can Be Saved in Three-Phase CT Urography? A Combination of Normal-Dose Corticomedullary Phase With Low-Dose Unenhanced and Excretory Phases
- 2012
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In: American Journal of Roentgenology. - 0361-803X .- 1546-3141. ; 199:4, s. 852-860
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Journal article (peer-reviewed)abstract
- OBJECTIVE:The purpose of this study was to investigate the degree to which the total radiation dose for CT urography can be lowered by selective reduction of the dose in the unenhanced and excretory phases when images in these phases are systematically evaluated alongside normal-dose corticomedullary phase images.SUBJECTS AND METHODS:Twenty-seven patients (mean age, 74 ± 9 years) underwent single-bolus CT urography with acquisition in the unenhanced, corticomedullary, and 5-minute excretory phases. The scanning parameters for normal-dose CT urography were as follows: 16 × 0.75 mm, 120 kV, and automatic exposure control technique reference tube loads of 100, 120, and 100 effective mAs (mAseff). The patients also underwent low-dose unenhanced and excretory phase scanning, in which the dose was escalated stepwise from a volume CT dose index (CTDIvol) of 1.7 to 6.6 mGy (reference 20-40-60-80 mAseff). Images were analyzed for quality and diagnostic confidence. If low-dose scans of three patients were inadequate, the study continued to the next dose level. When 20 patients were successfully included in the unenhanced and excretory phase groups, the study ended. Doses were calculated with a CT patient dosimetry calculator.RESULTS:Combined with the normal dose for corticomedullary phase scanning, doses of CTDIvol 1.5 mGy for the unenhanced phase and CTDIvol 2.7 mGy for the excretory phase were sufficient. The effective dose for three-phase CT urography was lowered from 16.2 to 9.4 mSv, a decrease of 42%. Diagnostic confidence in low-dose images was equal to that in normal-dose images when low-dose unenhanced and excretory phase images were read along-side normal-dose corticomedullary phase images.CONCLUSION:With a three-phase CT urographic protocol, significant dose reductions in the unenhanced and excretory phases can be achieved when these phases are combined with a normal-dose corticomedullary phase.
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| 3. |
- de Geer, Jakob, et al.
(author)
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Effect of Tube Voltage on Diagnostic Performance of Fractional Flow Reserve Derived From Coronary CT Angiography With Machine Learning: Results From the MACHINE Registry
- 2019
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In: American Journal of Roentgenology. - : AMER ROENTGEN RAY SOC. - 0361-803X .- 1546-3141. ; 213:2, s. 325-331
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Journal article (peer-reviewed)abstract
- OBJECTIVE. Coronary CT angiography (CCTA)-based methods allow noninvasive estimation of fractional flow reserve (cFFR), recently through use of a machine learning (ML) algorithm (cFFR(ML)). However, attenuation values vary according to the tube voltage used, and it has not been shown whether this significantly affects the diagnostic performance of cFFR and cFFR(ML). Therefore, the purpose of this study is to retrospectively evaluate the effect of tube voltage on the diagnostic performance of cFFR(ML). MATERIALS AND METHODS. A total of 525 coronary vessels in 351 patients identified in the MACHINE consortium registry were evaluated in terms of invasively measured FFR and cFFR(ML). CCTA examinations were performed with a tube voltage of 80, 100, or 120 kVp. For each tube voltage value, correlation (assessed by Spearman rank correlation coefficient), agreement (evaluated by intraclass correlation coefficient and Bland-Altman plot analysis), and diagnostic performance (based on ROC AUC value, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy) of the cFFR(ML) in terms of detection of significant stenosis were calculated. RESULTS. For tube voltages of 80, 100, and 120 kVp, the Spearman correlation coefficient for cFFR(ML) in relation to the invasively measured FFR value was rho = 0.684, rho = 0.622, and rho = 0.669, respectively (p amp;lt; 0.001 for all). The corresponding intraclass correlation coefficient was 0.78, 0.76, and 0.77, respectively (p amp;lt; 0.001 for all). Sensitivity was 100.0%, 73.5%, and 85.0%, and specificity was 76.2%, 79.0%, and 72.8% for tube voltages of 80, 100, and 120 kVp, respectively. The ROC AUC value was 0.90, 0.82, and 0.80 for 80, 100, and 120 kVp, respectively (p amp;lt; 0.001 for all). CONCLUSION. CCTA-derived cFFR(ML) is a robust method, and its performance does not vary significantly between examinations performed using tube voltages of 100 kVp and 120 kVp. However, because of rapid advancements in CT and postprocessing technology, further research is needed.
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| 4. |
- Kalra, Mannudeep K., et al.
(author)
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Sinogram-Affirmed Iterative Reconstruction of Low-Dose Chest CT: Effect on Image Quality and Radiation Dose
- 2013
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In: American Journal of Roentgenology. - : American Roentgen Ray Society (ARRS). - 0361-803X .- 1546-3141. ; 201:2, s. W235-W244
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Journal article (peer-reviewed)abstract
- OBJECTIVE. The purpose of this study is to compare sinogram-affirmed iterative reconstruction (SAFIRE) and filtered back projection (FBP) reconstruction of chest CT acquired with 65% radiation dose reduction.SUBJECTS AND METHODS. In this prospective study involving 24 patients (11 women and 13 men; mean [+/- SD] age, 66 +/- 10 years), two scan series were acquired using 100 and 40 Quality Reference mAs over a 10-cm scan length in the chest with a 128-MDCT scanner. The 40 Quality Reference mAs CT projection data were reconstructed with FBP and four settings of Safire (S1, S2, S3, and S4). Six image datasets (FBP with 100 and 40 Quality Reference mAs, and S1, S2, S3, S4 with 40 Quality Reference mAs) were displayed on a DICOM-compliant 55-inch 2-megapixel monitor for blinded evaluation by two thoracic radiologists for number and location of lesions, lesion size, lesion margins, visibility of small structures and fissures, and diagnostic confidence. Objective noise and CT values were measured in thoracic aorta for each image series, and the noise power spectrum was assessed. Data were analyzed with analysis of variance and Wilcoxon signed rank tests.RESULTS. All 186 lesions were seen on 40 Quality Reference mAs SAFIRE images. Diagnostic confidence on SAFIRE images was higher than that for FBP images. Except for the minor blotchy appearance on SAFIRE settings S3 and S4, no significant artifacts were noted. Objective noise with 40 Quality Reference mAs S1 images (21.1 +/- 6.1 SD of HU) was significantly lower than that for 40 Quality Reference mAs FBP images (28.5 +/- 8.1 SD of HU) (p andlt; 0.001). Noise power spectra were identical for SAFIRE and FBP with progressive noise reduction with higher iteration SAFIRE settings.CONCLUSION. Iterative reconstruction (SAFIRE) allows reducing the radiation exposure by approximately 65% without losing diagnostic information in chest CT.
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| 5. |
- Kemerink, Martijn, et al.
(author)
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Editorial Material: The Application of X-Rays in Radiology: From Difficult and Dangerous to Simple and Safe in AMERICAN JOURNAL OF ROENTGENOLOGY, vol 198, issue 4, pp 754-759
- 2012
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In: American Journal of Roentgenology. - : AMER ROENTGEN RAY SOC. - 0361-803X .- 1546-3141. ; 198:4, s. 754-759
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Journal article (other academic/artistic)abstract
- OBJECTIVE. This article will provide an assessment of the application of x-rays in the early days of radiology, which is an excellent way to come to value the convenience and safety of modern x-ray systems. CONCLUSION. The gas tubes that were originally applied for x-ray production were very unstable because of variations in the tubes vacuum. In an effort to understand some of the problems of these tubes and the high occupational exposure that was indirectly caused by the tubes erratic behavior, we measured x-ray output rates as a function of the gas pressure inside the tube. The pressure range for the optimal production of x-rays, using an original Ruhmkorff inductor as a high-voltage generator, was found to be narrow. With the vacuum changing over time, this might explain the many photographs from the first years of radiology with operators watching their unshielded tube, either with bare eyes or with a fluoroscope, and their own hand as a test object. This practice often led to severe damage of the hands and to many early deaths due to cancer. Today, after a century of technologic development of x-ray tubes and associated equipment, the total average effective dose of workers in radiology can be close to natural background levels.
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| 6. |
- Kim, Hae Young, et al.
(author)
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CT in Differentiating Complicated From Uncomplicated Appendicitis: Presence of Any of 10 CT Features Versus Radiologists Gestalt Assessment
- 2019
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In: American Journal of Roentgenology. - : AMER ROENTGEN RAY SOC. - 0361-803X .- 1546-3141. ; 213:5, s. W218-W226
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Journal article (peer-reviewed)abstract
- OBJECTIVE. The purpose of this study is to propose a sensitive CT criterion (the presence of any of 10 CT features) for complicated appendicitis that could be used in the nonoperative management of appendicitis and to compare the diagnostic performance of this sensitive CT criterion with that of gestalt assessment. MATERIALS AND METHODS. This retrospective study, which was conducted in a tertiary teaching hospital, included 100 patients with suspected appendicitis on CT. Complicated appendicitis, defined as gangrenous or perforated appendicitis, was pathologically or surgically confirmed in 32 patients. Six radiologists independently determined the presence of 10 previously reported CT features of complicated appendicitis (contrast enhancement defect of the appendiceal wall, abscess, extraluminal air, intraluminal air, extraluminal appendicolith, intraluminal appendicolith, moderate-to-severe periappendiceal fat stranding, periappendiceal fluid, ileus, and ascites) and rated the likelihood score for complicated appendicitis using gestalt assessment. The sensitivity and specificity of CT for complicated appendicitis were measured by the presence of any of 10 CT features (the any-of-10-features criterion) and by the radiologists gestalt assessment. Pooled sensitivity and specificity were compared using a generalized linear mixed model. RESULTS. The pooled sensitivity of the presence of any of 10 CT features was higher than that of gestalt assessment (92% vs 64%; difference, 28% [95% CI, 10-46%]; p amp;lt; 0.001), although the pooled specificity was lower (43% vs 76%; difference, -33% [95% CI, -48% to -17%]; p amp;lt; 0.001). CONCLUSION. The pooled sensitivity of the presence of any of 10 CT features was higher than that of gestalt assessment, at the cost of lower specificity. For prudent selection of patients who should receive nonoperative treatment of appendicitis, the any-of-10-features criterion may be used to decrease treatment failure associated with a false-negative diagnosis of complication.
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| 7. |
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| 8. |
- Mosavi, Firas, et al.
(author)
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Whole-Body Diffusion-Weighted MRI Compared With 18F-NaF PET/CT for Detection of Bone Metastases in Patients With High-Risk Prostate Carcinoma
- 2012
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In: American Journal of Roentgenology. - 0361-803X .- 1546-3141. ; 199:5, s. 1114-1120
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Journal article (peer-reviewed)abstract
- OBJECTIVE:The purpose of this study was to evaluate the accuracy of whole-body diffusion-weighted MRI (DWI) and 18F-NaF PET/CT for detection of bone metastases in patients with high-risk prostate cancer.SUBJECTS AND METHODS:Both patient- and lesion-based analyses were performed on 49 consecutive patients (median age, 67 years; age range, 57-80 years) with recently diagnosed high-risk prostate cancer. All patients underwent bone scintigraphy, whole-body MRI including DWI and 18F-NaF PET/CT before treatment. Bone scintigraphy, conventional MR images, and follow-up images were used as the standard of reference to evaluate 18F-NaF PET/CT and DWI.RESULTS:On patient-based analysis, five patients had skeletal metastases on reference imaging that both DWI and 18F-NaF PET/CT could verify, and 18F-NaF PET/CT and DWI showed false-positive findings in four and one patient, respectively. With lesion-based analysis, 18F-NaF PET/CT and DWI showed nine and five true-positive lesions, zero and four false-negative lesions, and seven and two false-positive lesions, respectively. Two patients with uncountable bone metastases were analyzed separately. In these patients, 18F-NaF PET/CT showed more bone metastases than did DWI.CONCLUSION:We believe 18F-NaF PET/CT is a sensitive modality for detection of bone metastases caused by prostate cancer. Whole-body DWI shows a higher specificity but lower sensitivity than 18F-NaF PET/CT. Future studies with a larger patient cohort along with analyses of costs and clinical availability are needed before implementation of these methods can be considered.
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