Background Computed tomography (CT) is a central modality in modern radiology contributing to diagnostic medicine in almost every medical subspecialty, but particularly in emergency services. To solve the inverse problem of reconstructing anatomical slice images from the raw output the scanner measures, several methods have been developed, with filtered back projection (FBP) and iterative reconstruction (IR) subsequently providing criterion standards. Currently there are new approaches to reconstruction in the field of artificial intelligence utilizing the upcoming possibilities of machine learning (ML), or more specifically, deep learning (DL). Method This review covers the principles of present CT image reconstruction as well as the basic concepts of DL and its implementation in reconstruction. Subsequently commercially available algorithms and current limitations are being discussed. Results and Conclusion DL is an ML method that utilizes a trained artificial neural network to solve specific problems. Currently two vendors are providing DL image reconstruction algorithms for the clinical routine. For these algorithms, a decrease in image noise and an increase in overall image quality that could potentially facilitate the diagnostic confidence in lesion conspicuity or may translate to dose reduction for given clinical tasks have been shown. One study showed equal diagnostic accuracy in the detection of coronary artery stenosis for DL reconstructed images compared to IR at higher image quality levels. Consequently, a lot more research is necessary and should aim at diagnostic superiority in the clinical context covering a broadness of pathologies to demonstrate the reliability of such DL approaches. Key Points: Citation Format
Purpose To assess radiation exposure in men undergoing prostate artery embolization (PAE) for the treatment for symptomatic, benign prostatic hyperplasia depending on growing experience of interventional radiologists over a 4-year period. Methods A total of 250 consecutive patients underwent PAE at a single center. Data on radiation exposure [dose area product (DAP), effective dose (ED), entrance skin dose (ESD), and fluoroscopy time (FT)] were retrospectively evaluated. Primary outcomes of interest were patient radiation exposure in five consecutive groups of 50 patients each and Pearson correlation with the number of patients treated. Results Median DAP, ED, and ESD during prostate artery embolization were significantly higher in the first compared to the second 50 patients (56 298 µGym 2 vs. 24 709 µGym 2 , p < 0.001, 146.4 mSv vs. 64.2 mSv, p < 0.001, and 5.1 Gy vs. 2.4 Gy, p < 0.001, respectively). The following consecutive groups did not differ significantly from the respective preceding group in terms of DAP, ED, and ESD. Number of digital subtraction angiography series, FT, and procedure time decreased with increasing operator experience (Pearson’s r = − 0.240, p < 0.001, r = − 0.269, p < 0.001, and r = − 0.504, p < 0.001, respectively). Bilateral prostate artery embolization was associated with less ESD and shorter FT than unilateral embolization (median 2.5 vs. 3.5 Gy, p = 0.02, and 26 min vs. 42 min, p < 0.001, respectively). Conclusion Exposure to radiation in men who underwent PAE decreased with growing operator experience and decreasing complexity of procedures.
Purpose To evaluate the effect of cone-beam computed tomography (CBCT) on radiation exposure, procedure time, and contrast media (CM) use in prostatic artery embolization (PAE). Materials and Methods Seventy-eight patients were enrolled in this retrospective, single-center study. All patients received PAE without (group A; n = 39) or with (group B; n = 39) CBCT. Total dose-area product (DAPtotal; Gycm2), total entrance skin dose (ESDtotal; mGy), and total effective dose (EDtotal; mSv) were primary outcomes. Number of digital subtraction angiography (DSA) series, CM use, fluoroscopy time, and procedure time were secondary outcomes. PAE in group A was performed by a single radiologist with 15 years experience, PAE in group B was conducted by four radiologists with 4 to 6 years experience. Results For groups A vs. B, respectively, median (IQR): DAPtotal 236.94 (186.7) vs. 281.20 (214.47) Gycm2(p = 0.345); EDtotal 25.82 (20.35) vs. 39.84 (23.75) mSv (p = < 0.001); ESDtotal 2833 (2278) vs. 2563 (3040) mGy(p = 0.818); number of DSA series 25 (15) vs. 23 (10)(p = 0.164); CM use 65 (30) vs. 114 (40) mL(p = < 0.001); fluoroscopy time 23 (20) vs. 28 (25) min(p = 0.265), and procedure time 70 (40) vs.120 (40) min(p = < 0.001). Bilateral PAE was achieved in 33/39 (84.6%) group A and 32/39 (82.05%) group B(p = 0.761), all other patients received unilateral PAE. There were no significant differences between clinical parameters and origins of the prostatic arteries (PA) (p = 0.206–1.00). Conclusion Operators with extensive expertise on PAE may not benefit from addition of CBCT to DSA runs, whereas for operators with less expertise, CBCT when used alongside with DSA runs increased the overall radiation exposure.
Background Patients with cirrhosis and ascites (and portal hypertension) are at risk of developing acute kidney injury (AKI). Although many etiologies exist, hepatorenal AKI (HRS-AKI) remains a frequent and difficult-to-treat cause, with a very high mortality when left untreated. The standard of care is the use of terlipressin and albumin. This can lead to reversal of AKI, which is associated to survival. Nevertheless, only approximately half of the patients achieve this reversal and even after reversal patients remains at risk for new episodes of HRS-AKI. TIPS is accepted for use in patients with variceal bleeding and refractory ascites, which leads to a reduction in portal pressure. Although preliminary data suggest it may be useful in HRS-AKI, its use in this setting is controversial and caution is recommended given the fact that HRS-AKI is associated to cardiac alterations and acute-on-chronic liver failure (ACLF) which represent relative contraindications for transjugular intrahepatic portosystemic shunt (TIPS). In the last decades, with the new definition of renal failure in patients with cirrhosis, patients are identified at an earlier stage. These patients are less sick and therefore more likely to not have contraindications for TIPS. We hypothesize that TIPS could be superior to the standard of care in patients with HRS-AKI. Methods This study is a prospective, multicenter, open, 1:1-randomized, controlled parallel-group trial. The main end-point is to compare the 12-month liver transplant-free survival in patients assigned to TIPS compared to the standard of care (terlipressin and albumin). Secondary end-point include reversal of HRS-AKI, health-related Quality of Life (HrQoL), and incidence of further decompensation among others. Once patients are diagnosed with HRS-AKI, they will be randomized to TIPS or Standard of Care (SOC). TIPS should be placed within 72 h. Until TIPS placement, TIPS patients will be treated with terlipressin and albumin. Once TIPS is placed, terlipressin and albumin should be weaned off according to the attending physician. Discussion If the trial were to show a survival advantage for patients who undergo TIPS placement, this could be incorporated in routine clinical practice in the management of patients with HRS-AKI. Trial registration Clinicaltrials.gov NCT05346393. Released to the public on 01 April 2022.
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