Validation of a Novel Methodology to Evaluate Changes in the Flare Geometry of Renovisceral Bridging Stent-Grafts After Fenestrated Endovascular Aneurysm Repair.

Purpose: To validate a novel method to evaluate changes in the geometry of renovisceral bridging stent-grafts (BSGs) in patients undergoing fenestrated endovascular aneurysm repair (fEVAR). Materials and Methods: Retrospective analysis was conducted of serial computed tomography angiograms (CTAs) of 10 fEVAR patients (31 BSGs) with at least 2 years of CTA follow-up. Centerline reconstructions were made through the fenestrated stent-graft (FSG) and each BSG. Flare geometry was reconstructed based on marker coordinates and a mesh of the aortic lumen. The shortest distance was calculated from the top of the flare circumference to the FSG fabric. The amount of flaring was assessed with the flare to fenestration diameter ratio and BSG compression to diameter ratio (D-ratio). All measurements were performed by 2 observers. Interobserver variability was assessed; results are presented as the intraclass correlation coefficient (ICC) and repeatability coefficient (RC). Results: Excellent interobserver agreement was achieved for BSG diameter and flare to fenestration distance calculations (ICC 0.865 and 0.944; RC 2.2% and 4.5%, respectively). Six patients had BSG-related complications during follow-up: 2 type IIIc endoleaks and 4 BSG occlusions. Five of the 6 BSGs with complications showed a considerable change in the D-ratio compared with the first postoperative CTA. Conclusion: Precise assessment of the geometry of visceral BSGs in fEVAR is feasible with the presented method. Geometrical changes that may precede later complications can be detected, which could aid in localization of the origin, but a larger series of patients is necessary to define its true clinical merit.

Potential for dose reduction in CT emphysema densitometry with post-scan noise reduction: a phantom study.

OBJECTIVE: The aim of this phantom study was to investigate the effect of scan parameters and noise suppression techniques on the minimum radiation dose for acceptable image quality for CT emphysema densitometry. METHODS: The COPDGene phantom was scanned on a third generation dual-source CT system with 16 scan setups (CTDIvol 0.035-10.680 mGy). Images were reconstructed at 1.0/0.7 mm slice thickness/increment, with three kernels (one soft, two hard), filtered backprojection and three grades of third-generation iterative reconstruction (IR). Additionally, deep learning-based noise suppression software was applied. Main outcomes: overlap in area of the normalized histograms of CT density for the emphysema insert and lung material, and the radiation dose required for a maximum of 4.3% overlap (defined as acceptable image quality). RESULTS: In total, 384 scan reconstructions were analyzed. Decreasing radiation dose resulted in an exponential increase of the overlap in normalized histograms of CT density. The overlap was 11-91% for the lowest dose setting (CTDIvol 0.035mGy). The soft kernel reconstruction showed less histogram overlap than hard filter kernels. IR and noise suppression also reduced overlap. Using intermediate grade IR plus noise suppression software allowed for 85% radiation dose reduction while maintaining acceptable image quality. CONCLUSION: CT density histogram overlap can quantify the degree of discernibility of emphysema and healthy lung tissue. Noise suppression software, IR, and soft reconstruction kernels substantially decrease the dose required for acceptable image quality. ADVANCES IN KNOWLEDGE: Noise suppression software, IR, and soft reconstruction kernels allow radiation dose reduction by 85% while still allowing differentiation between emphysema and normal lung tissue.

Validation of automatic joint space width measurements in hand radiographs in rheumatoid arthritis.

Computerized methods promise quick, objective, and sensitive tools to quantify progression of radiological damage in rheumatoid arthritis (RA). Measurement of joint space width (JSW) in finger and wrist joints with these systems performed comparable to the Sharp-van der Heijde score (SHS). A next step toward clinical use, validation of precision and accuracy in hand joints with minimal damage, is described with a close scrutiny of sources of error. A recently developed system to measure metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints was validated in consecutive hand images of RA patients. To assess the impact of image acquisition, measurements on radiographs from a multicenter trial and from a recent prospective cohort in a single hospital were compared. Precision of the system was tested by comparing the joint space in mm in pairs of subsequent images with a short interval without progression of SHS. In case of incorrect measurements, the source of error was analyzed with a review by human experts. Accuracy was assessed by comparison with reported measurements with other systems. In the two series of radiographs, the system could automatically locate and measure 1003/1088 (92.2%) and 1143/1200 (95.3%) individual joints, respectively. In joints with a normal SHS, the average (SD) size of MCP joints was [Formula: see text] and [Formula: see text] in the two series of radiographs, and of PIP joints [Formula: see text] and [Formula: see text]. The difference in JSW between two serial radiographs with an interval of 6 to 12 months and unchanged SHS was [Formula: see text], indicating very good precision. Errors occurred more often in radiographs from the multicenter cohort than in a more recent series from a single hospital. Detailed analysis of the 55/1125 (4.9%) measurements that had a discrepant paired measurement revealed that variation in the process of image acquisition (exposure in 15% and repositioning in 57%) was a more frequent source of error than incorrect delineation by the software (25%). Various steps in the validation of an automated measurement system for JSW of MCP and PIP joints are described. The use of serial radiographs from different sources, with a short interval and limited damage, is helpful to detect sources of error. Image acquisition, in particular repositioning, is a dominant source of error.

The Preoperative CT-Scan Can Help to Predict Postoperative Complications after Pancreatoduodenectomy.

After pancreatoduodenectomy, complication rates are up to 40%. To predict the risk of developing postoperative pancreatic fistula or severe complications, various factors were evaluated. 110 consecutive patients undergoing pancreatoduodenectomy at our institute between January 2012 and September 2014 with complete CT scan were retrospectively identified. Pre-, per-, and postoperative patients and pathological information were gathered. The CT-scans were analysed for the diameter of the pancreatic duct, attenuation of the pancreas, and the visceral fat area. All data was statistically analysed for predicting POPF and severe complications by univariate and multivariate logistic regression analyses. The POPF rate was 18%. The VFA measured at umbilicus (OR 1.01; 95% CI = 1.00-1.02; P = 0.011) was an independent predictor for POPF. The severe complications rate was 33%. Independent predictors were BMI (OR 1.24; 95% CI = 1.10-1.42; P = 0.001), ASA class III (OR 17.10; 95% CI = 1.60-182.88; P = 0.019), and mean HU (OR 0.98; 95% CI = 0.96-1.00; P = 0.024). In conclusion, VFA measured at the umbilicus seems to be the best predictor for POPF. BMI, ASA III, and the mean HU of the pancreatic body are independent predictors for severe complications following PD.