Revised Swedish guidelines on intravenous iodine contrast medium-induced acute kidney injury 2022: A summary.

The Swedish Society of Uroradiology has revised their computed tomography (CT) guidelines regarding iodine contrast media-induced acute kidney injury (CI-AKI). They are more cautious compared to the European Society of Urogenital Radiology and the American College of Radiology since the actual risk of CI-AKI remains uncertain in patients with moderate to severe kidney damage due to a lack of prospective controlled studies and mainly based on retrospective propensity score-matched studies with low-grade evidence. Another source of uncertainty is the imprecision of glomerular filtration rate (GFR) estimating equations. However, randomized hydration studies indictae an upper limit risk of CI-AKI of about 5% for outpatients with a GFR in the range of 30-44 or 45-59 mL/min/1.73m2 combined with multiple risk factors. Apart from GFR limits, the guideline also includes limits for systemic contrast medium exposure expressed in gram-iodine/GFR ratio.

Diagnostic accuracy of dual-energy CT for detection of bone marrow lesions in the subacutely injured knee with MRI as reference method.

BACKGROUND: Dual-energy computer tomography (DECT) can detect post-traumatic bone marrow lesions. Prospective studies of the knee with large numbers of participants and intra-observer agreement assessment are limited. PURPOSE: To investigate the diagnostic accuracy of DECT in detecting bone marrow lesions as well as estimating the bone marrow lesion volume in patients with suspected anterior cruciate ligament trauma with magnetic resonance imaging (MRI) as reference standard. MATERIAL AND METHODS: Forty-eight consecutive patients with suspected anterior cruciate ligament injury were imaged bilaterally with DECT within a mean of 25 days (range 4-55 days) following injury and MRI within seven days of DECT. Two readers analyzed DECT virtual non-calcium-blinded images. Consensus MRI was reference standard. Intra- and inter-observer agreement were determined using weighted kappa statistics. Sensitivity, specificity, and negative and positive predictive values were calculated. Bone marrow lesion volumes were measured; for comparison, intra-class correlation coefficient was used. RESULTS: The 48 patients (26 men, 22 women; mean age 23 years, age range 15-37 years) were imaged bilaterally yielding 52 knees with bone marrow lesions, of which 44 were in the femur and 41 were in the tibia. Intra- and inter-observer agreement to detect bone marrow lesions was moderate and fair to moderate (κ 0.54-0.66, 95% confidence interval [CI] 0.39-0.80 and 0.37-0.41, 95% CI 0.20-0.57) and overall sensitivity and specificity were 70.1% and 69.1%, respectively. Positive and negative predictive values were 72.9% and 66.1%, respectively. Bone marrow lesion volumes showed excellent intra- and inter-observer agreement (0.83-0.91, 95% CI 0.74-0.94 and 0.76-0.78, 95% CI 0.57-0.87). CONCLUSION: The diagnostic performance of DECT to detect bone marrow lesions in the subacutely injured knee was moderate with intra- and inter-observer agreement ranging from moderate to substantial and fair to moderate. Bone marrow lesion volume correlation was excellent.

Radiation dose reduction with Sinogram Affirmed Iterative Reconstruction technique for abdominal computed tomography.

PURPOSE: The objective of this study was to assess the effect of Sinogram Affirmed Iterative Reconstruction (SAFIRE) and filtered back-projection (FBP) techniques on abdominal computed tomography (CT) performed with 50% and 75% radiation dose reductions. METHODS: Twenty-four patients (mean age, 64 ± 14 years; male-female ratio, 10:14) gave informed consent for an institutional review board-approved prospective study involving acquisition of additional research images through the abdomen on 128-slice multi-detector-row CT (SOMATOM Definition Flash) at quality reference mAs of 100 (50% lower dose) and 50 (75% lower dose) over a scan length of 10 cm using combined modulation (CARE Dose 4D). Standard-of-care abdominal CT was performed at 200 quality reference mAs, with remaining parameters held constant. The 50- and 100-mAs data sets were reconstructed with FBP and at 4 SAFIRE settings (S1, S2, S3, S4). Higher number of SAFIRE settings denotes increased strength of the algorithm resulting in lower image noise. Two abdominal radiologists independently compared the FBP and SAFIRE images for lesion number, location, size and conspicuity, and visibility of small structures, image noise, and diagnostic confidence. Objective noise and Hounsfield units (HU) were measured in the liver and the descending aorta. RESULTS: All 43 lesions were detected on both FBP and SAFIRE images. Minor blocky, pixelated appearance of 50% and 75% reduced dose images was noted at S3 and S4 SAFIRE but not at S1 and S2 settings. Subjective noise was suboptimal in both 50% and 75% lower-dose FBP images but was deemed acceptable on all SAFIRE settings. Sinogram Affirmed Iterative Reconstruction images were deemed acceptable in all patients at 50% lower dose and in 22 of 24 patients at 75% lower dose. As compared with 75% reduced dose FBP, objective noise was lower by 22.8% (22.9/29.7), 35% (19.3/29.7), 44.3% (16.7/29.3), and 54.8% (13.4/29.7) on S1 to S4 settings, respectively (P < 0.001). CONCLUSIONS: Sinogram Affirmed Iterative Reconstruction-enabled reconstruction provides abdominal CT images without loss in diagnostic value at 50% reduced dose and in some patients also at 75% reduced dose.

A state-of-the-art pipeline for postmortem CT and MRI visualization: from data acquisition to interactive image interpretation at autopsy.

The importance of autopsy procedures leading to the establishment of the cause of death is well-known. A recent addition to the autopsy work flow is the possibility of conducting postmortem imaging, in its 3D version also called virtual autopsy (VA), using multidetector computed tomography (MDCT) or magnetic resonance imagining (MRI) data from scans of cadavers displayed with direct volume rendering (DVR) 3D techniques. The use of the data and their workflow are presented. Data acquisition was performed and high quality data-sets with submillimeter precision were acquired. New data acquisition techniques such as dual-energy CT (DECT) and quantitative MRI, then were implemented and provided additional information. Particular findings hardly visualized in conventional autopsy can rather easy be seen at the full body CT, such as air distribution, e.g. pneumothorax, pneumopericardium, air embolism, and wound channels. MRI shows natural deaths such as myocardial infarctions. Interactive visualization of these 3D data-sets can provide valuable insight into the corpses and enables non-invasive diagnostic procedures. In postmortem CT imaging, not being limited by a patient depending radiation dose limit the data-sets can, however, be generated with such a high resolution that they become difficult to handle in today's archive retrieval and interactive visualization systems, specifically in the case of full body scans. To take full advantage of these new technologies the postmortem workflow needs to be tailored to the demands and opportunities that the new technologies allow.

Quantitative analysis of the patellofemoral motion pattern using semi-automatic processing of 4D CT data.

PURPOSE: To present a semi-automatic method with minimal user interaction for quantitative analysis of the patellofemoral motion pattern. METHODS: 4D CT data capturing the patellofemoral motion pattern of a continuous flexion and extension were collected for five patients prone to patellar luxation both pre- and post-surgically. For the proposed method, an observer would place landmarks in a single 3D volume, which then are automatically propagated to the other volumes in a time sequence. From the landmarks in each volume, the measures patellar displacement, patellar tilt and angle between femur and tibia were computed. RESULTS: Evaluation of the observer variability showed the proposed semi-automatic method to be favorable over a fully manual counterpart, with an observer variability of approximately 1.5[Formula: see text] for the angle between femur and tibia, 1.5 mm for the patellar displacement, and 4.0[Formula: see text]-5.0[Formula: see text] for the patellar tilt. The proposed method showed that surgery reduced the patellar displacement and tilt at maximum extension with approximately 10-15 mm and 15[Formula: see text]-20[Formula: see text] for three patients but with less evident differences for two of the patients. CONCLUSIONS: A semi-automatic method suitable for quantification of the patellofemoral motion pattern as captured by 4D CT data has been presented. Its observer variability is on par with that of other methods but with the distinct advantage to support continuous motions during the image acquisition.