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Medical Imaging Phantoms (MIPs) calibrate imaging devices, train medical professionals, and can help procedural planning. Traditional MIPs are costly and limited in customization. Additive manufacturing allows for customizable, patient-specific phantoms. This study examines the CT attenuation characteristics of contrast-injectable, chambered 3D-printed phantoms to optimize tissue-mimicking capabilities. A MIP was constructed from a CT of a complex pelvic tumor near the iliac bifurcation. A 3D reconstruction of these structures composed of three chambers (aorta, inferior vena cava, tumor) with ports for contrast injection was 3D printed. Desired attenuations were 200 HU (arterial I), 150 HU (venous I), 40 HU (tumor I), 150 HU (arterial II), 90 HU (venous II), and 400 HU (tumor II). Solutions of Optiray 350 and water were injected, and the phantom was scanned on CT. Attenuations were measured using ROIs. Mean attenuation for the six phases was as follows: 37.49 HU for tumor I, 200.50 HU for venous I, 227.92 HU for arterial I, 326.20 HU for tumor II, 91.32 HU for venous II, and 132.08 HU for arterial II. Although the percent differences between observed and goal attenuation were high, the observed relative HU differences between phases were similar to goal HU differences. The observed attenuations reflected the relative concentrations of contrast solutions used, exhibiting a strong positive correlation with contrast concentration. The contrast-injectable tumor phantom exhibited a useful physiologic range of attenuation values, enabling the modification of tissue-mimicking 3D-printed phantoms even after the manufacturing process. [ABSTRACT FROM AUTHOR]

Three-dimensionally printed phantoms are increasingly used in medical imaging and research due to their cost-effectiveness and customizability, offering valuable alternatives to commercial phantoms. The purpose of this study was to assess the computed tomography (CT) attenuation characteristics of 27 resin materials from Formlabs, a 3D printing equipment and materials manufacturer. Cube phantoms (both solid and hollow constructions) produced with each resin were subjected to CT scanning under varying tube current–time products with attenuation measurements recorded in Hounsfield units (HU). The resins exhibited a wide range of attenuation values (−3.33 to 2666.27 HU), closely mimicking a range of human tissues, from fluids to dense bone structures. The resins also demonstrated consistent attenuation regardless of changes in the tube current. The CT attenuation analysis of FormLabs resins produced an archive of radiological imaging characteristics of photopolymers that can be utilized to construct more accurate tissue mimicking medical phantoms and improve the evaluation of imaging device performance. [ABSTRACT FROM AUTHOR]

Objectives: To identify PanNEN imaging features associated with tumor grade and aggressive histopathological features. Methods: Associations between histopathological and imaging features of resected PanNEN were retrospectively tested. Histopathologic features included WHO grade, lymphovascular invasion (LVI), growth pattern (infiltrative, circumscribed), and intratumoral fibrosis (mature, immature). Imaging features included size, degree/uniformity of enhancement, progressive enhancement, contour, infiltrative appearance (infiltrativeim), calcifications, cystic components, tumor thrombus, vascular occlusion (VO), duct dilatation, and atrophy. Multinomial logistic regression analyses evaluated the magnitude of associations. Association of variables with outcome was assessed using Cox-proportional hazards regression. Results: 133 patients were included. 3 imaging features (infiltrativeim, ill-defined contour [contourill], and VO) were associated with all histopathologic parameters and poor outcome. Increase in grade increased odds of contourill by 15.6 times (p = 0.0001, 95% CI 3.8–64.4). PanNEN with VO were 51.1 times (p = 0.0002, 6.5–398.6) more likely to demonstrate LVI. For PanNEN with contourill, infiltrative growth pattern was 51.3 times (p < 0.0001, 9.1–288.4), and fibrosis was 14 times (p = 0.0065, 2.1–93.7) more likely. Contourill was associated with decreased recurrence-free survival (p = 0.0003, HR 18.29, 3.83–87.3) and VO (p = 0.0004, HR6.08, 2.22–16.68) with decreased overall survival. Conclusions: Infiltrativeim, contourill, and VO on imaging are associated with higher grade/histopathological parameters linked to tumor aggression, and poor outcome. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to assess the added diagnostic value of Doppler ultrasound of the liver (DUL) performed within 3 days of contrast-enhanced CT (CECT) for the diagnosis of portal vein (PV) or hepatic vein (HV) thrombosis. Methods: Adult patients were included if they underwent DUL within three days after a CECT of the abdomen in the emergency or inpatient setting. Retrospective review of clinical data and imaging reports was performed. In patients with discrepant or positive findings on CECT and/or DUL with respect to PV or HV thrombosis, image review was performed by three fellowship-trained abdominal radiologists in consensus. Results: The final cohort consisted of 468 patients. Of these, 26 (5.6%) patients had equivocal findings for thrombosis on CECT, and DUL could make a confident diagnosis of positive or negative in 18 (69%) patients. Additionally, there were 2 (0.4%) patients with PV or HV thrombosis on DUL following a limited CECT, and 2 (0.4%) patients who developed interval PV thrombosis between CECT and DUL. Conclusion: DUL after CECT added diagnostic value for PV and/or HV thrombosis in less than 5% of patients. The patency of PV and HV is often not explicitly mentioned in CECT reports at our institution, which may lead to uncertainty for the referring provider as to whether the PV and HV were adequately evaluated. Few CECT have false positive or missed or underreported findings, and a careful review of the original CECT should be performed if DUL is requested. [ABSTRACT FROM AUTHOR]