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Purpose CT findings of hospitalized COVID-19 patients were analyzed during both the first and the second waves of the pandemic, in order to detect any significant differences between the two groups. Methods In this observational, retrospective, monocentric study, all hospitalized patients who underwent CT for suspected COVID-19 pneumonia from February 27 to March 27, 2020 (first wave) and from October 26 to November 24, 2020 (second wave) were enrolled. Epidemiological data, radiological pattern according to the RSNA consensus statement and visual score extension using a semi-quantitative score were compared. Results Two hundred and eleven patients (mean age, 64.52 years ± 15.14, 144 males) were evaluated during the first wave while 455 patients (mean age, 68.26 years ± 16.34, 283 males) were studied during the second wave. The same prevalence of patterns was documented in both the first and the second waves (p = 0.916), with non-typical patterns always more frequently observed in elderly patients, especially the “indeterminate” pattern. Compared to those infected during the first wave, the patients of the second wave were older (64.52 vs.68.26, p = 0.005) and presented a slightly higher mean semi-quantitative score (9.0 ± 2.88 vs. 8.4 ± 3.06, p = 0.042). Age and semi-quantitative score showed a positive correlation (r = 0.15, p = 0.001). Conclusions There was no difference regarding CT pattern prevalence between the first and the second waves, confirming both the validity of the RSNA consensus and the most frequent radiological COVID-19 features. Non-typical COVID-19 features were more frequently observed in older patients, thus should not be underestimated in the elderly population.

Liver cirrhosis is a leading cause of death worldwide, with 1-year mortality rates of up to 57% in decompensated patients. Hepatocellular carcinoma (HCC) is the most common primary tumor in cirrhotic livers and the second leading cause of cancer-related mortality worldwide. Annually, up to 8% of patients with cirrhosis develop HCC. The diagnosis of HCC rarely requires histological confirmation: in fact, according to the most recent guidelines, the imaging features of HCC are almost always sufficient for a certain diagnosis. Thus, the role of the radiologist is pivotal because the accurate detection and characterization of focal liver lesions in patients with cirrhosis are essential in improving clinical outcomes. Despite recent technical innovations in liver imaging, several issues remain for radiologists regarding the differentiation of HCC from other hepatic lesions, particularly benign lesions and pseudolesions. It is important to avoid misdiagnosis of benign liver lesions as HCC (false-positive cases) because this diagnostic misinterpretation may lead to ineligibility of a patient for potentially curative treatments or inappropriate assignment of high priority scores to patients on waiting lists for liver transplantation. This review presents a pocket guide that could be useful for the radiologist in the diagnosis of benign lesions and pseudolesions in cirrhotic livers, highlighting the imaging features that help in making the correct diagnosis of macroregenerative nodules; siderotic nodules; arterioportal shunts; hemangiomas, including fast-filling hemangiomas, hemangiomas with pseudowashout, and sclerosed hemangiomas; confluent fibrosis; pseudomasses in chronic portal vein thrombosis; and focal fatty changes.

Purpose: To evaluate the diagnostic accuracy of the four standardized categories for CT reporting proposed by the Radiological Society of North America (RSNA) to support a faster triage compared with real-time reverse-transcription polymerase chain reaction (RTPCR), which is the reference standard for suspected coronavirus disease 2019 (COVID-19), but has long reporting time (6–48 hours). Materials and Methods: A retrospective analysis of 569 thin-section CT examinations performed for patients suspected of having COVID-19 from February 27 to March 27, 2020 (peak of infection in Italy) was conducted. The imaging pattern was classified according to the statement by the RSNA as “typical,” “indeterminate,” “atypical,” and “negative” and compared with RT-PCR for 460 patients. Interobserver variability in reporting between a senior and a junior radiologist was evaluated. Use of the vascular enlargement sign in indeterminate cases was also assessed. Results: The diagnosis of COVID-19 was made in 45.9% (211/460) of patients. The “typical” pattern (n = 172) showed a sensitivity of 71.6%, a specificity of 91.6%, and a positive predictive value of 87.8% for COVID-19. The “atypical” (n = 67) and “negative” (n =123) pattern demonstrated a positive predictive value of 89.6% and 86.2% for non–COVID-19, respectively. The “indeterminate” (n = 98) pattern was nonspecific, but vascular enlargement was most frequently found in patients with COVID-19 (86.1%; P , .001). Interobserver agreement was good for the “typical” and “negative” pattern and fair for “indeterminate” and “atypical” (k = 0.5; P =.002). Conclusion: In an epidemic setting, the application of the four categories proposed by the RSNA provides a standardized diagnostic hypothesis, strongly linked to the RT-PCR results for the “typical,” “atypical,” and “negative” pattern. In the “indeterminate” pattern, the analysis of the vascular enlargement sign could facilitate the interpretation of imaging features.

The Liver Imaging Reporting and Data System (LI-RADS) is a widespread comprehensive system for standardising the reporting and data collection of liver imaging to standardise chronic liver disease evaluation. However, the LI-RADS, based on the identification of some categories of lesions by means of a conceptual and nonquantitative probability approach, has many limitations. In fact, recently, the European Association for the Study of the Liver Guidelines regarding the management of hepatocellular carcinoma did not accept the LI-RADS. The aim of this paper was to critically analyse the LI-RADS, focusing on some interesting issues such as the absence of a clear distinction between two different imaging modalities (computed tomography and MRI), the lack of validation of some major features, the assessment of its ancillary features and its complexity. Despite these limitations, the LI-RADS represents a great opportunity for the radiological community. We must not let it escape, but time and experience are necessary for its improvement. Copyright (C) 2018 Wolters Kluwer Health, Inc. All rights reserved.

Aims: Texture analysis (TA) is becoming an increasingly used tool in radiological research. Some papers have been published on its use in ultrasound (US), but the way in which the machine settings affect the features has not yet been fully explored. With this research, we analyze how the time gain compensation (TGC) influences the features of the gray-level matrices in the abdominal US setting. Subjects and Methods: We analyzed the images acquired from the hepatorenal acoustic window of a healthy 29-year-old volunteer acquired with different TGC settings. TA was carried out using the LifeX software. Results: Several both 1st and 2nd order gray-level matrices features showed a strong correlation with TGC settings. Conclusions: TGC settings must be accounted for when carrying out further TA studies.

To prospectively assess the additional value of the hepatobiliary (HB) phase of Gd-EOB-DTPA-MRI in identifying and characterising small (≤ 2 cm) hepatocellular carcinomas (HCCs) undetermined in dynamic phases alone because of their atypical features, according to the AASLD criteria.127 cirrhotic patients were evaluated with Gd-EOB-DTPA-MRI in two sets: unenhanced and dynamic phases; unenhanced, dynamic and HB phases. Sixty-two out of 215 nodules (29%) were atypical in 42 patients (33%).62 atypical nodules were reported at histology: high-grade dysplastic nodules (HGDN)/early HCC (n = 20), low-grade DN (LGDN) (n = 21), regenerative nodules (n = 17) and nodular regenerative hyperplasia (n = 4). The sensitivity, specificity, accuracy, positive and negative predictive value (PPV, NPV) were increased by the addition of the HB phase: 88.4-99.4%, 88-95%, 88-98.5%, 97-99%, and 65-97.5%, respectively. Twenty atypical nodules were malignant (32%), 19 of which were characterised only during the HB phase.The HB phase is 11% more sensitive in the classification of HGDN/early HCC than dynamic MRI, with an added value of 32.5% in the NPV. The high incidence (33%) of atypical nodules and their frequent malignancy (32%) suggest the widespread employment of Gd-EOB-DTPA-MRI in the follow-up of small nodules (≤ 2 cm) in cirrhosis.

To prospectively evaluate the ability of macromolecular contrast medium (MMCM)-enhanced dynamic magnetic resonance (MR) imaging to depict vascular changes in response to cyclooxygenase-2 (COX-2) inhibition of angiogenesis in a human breast cancer model.The institutional committee for animal research approved this study. A human breast cancer cell line, MDA-MB-231, was implanted in 30 female homozygotous athymic rats that were alternately assigned to either a drug treatment group that received celecoxib on a daily basis for 7 days or a control group that received saline. Each animal underwent MR imaging after intravenous administration of a high-molecular-weight contrast agent at baseline and again 24 hours and 7 days after administration. Eleven rats in each group successfully underwent all three studies and had data sets of sufficient technical quality. A bidirectional two-compartment tissue model was used to estimate transendothelial permeability (K(PS)) and fractional plasma volume (fPV) for each tumor. Microvessel density was also measured to enable histologic assessment of angiogenesis. Repeated-measures analysis of variance and unpaired two-tailed t tests were used to evaluate differences in mean values between MR examinations performed in the same rats and between baseline values in treated and control rats, respectively.MR imaging-assayed microvascular K(PS) decreased significantly after 7 days of treatment with celecoxib (P.05), but it was not significantly changed after 7 days in the control group. Likewise, microvascular density, a histologic surrogate of angiogenesis, was significantly (P.05) lower in the treatment group than in the control group. The fPV did not significantly change in either group.Dynamic MR imaging revealed microvascular permeability to a high-molecular-weight contrast agent was significantly reduced by treatment with celecoxib.

Rationale and Objectives This study was performed to evaluate the relationship between dose levels of contrast medium and image quality in magnetic resonance (MR) angiography of the carotid arteries with fluoroscopically monitored, manually triggered, elliptically ordered image acquisitions. Materials and Methods Twenty-five patients with clinical indications for angiography of the carotid arteries were examined with MR at 1.5 T by using a fluoroscopically monitored, manually triggered, elliptically ordered pulse sequence with the administration of one of three different volumes of gadolinium-based contrast medium. The signal intensities of the vessel lumen and the surrounding tissues were measured in single partitions at the origin of the common carotid artery, the carotid bifurcation, and the intracranial internal carotid arteries. The contrast-to-noise ratio in these regions of interest also was measured. Maximum intensity projection image quality was appraised for blurring, artifacts, venous enhancement, background suppression, and contrast medium distribution. Results No artifacts or venous enhancement was observed. The position of the fluoroscopic section affected the distribution of contrast medium along the vessel, as evidenced by the difference between the contrast-to-noise ratio at the origin of the common carotid artery and the ratio at the carotid bifurcation and the intracranial internal carotid arteries (P < .01). The contrast medium dose administered was strongly correlated with image quality (r = 0.90). Conclusion Contrast medium dose is related to image quality in MR angiography of the carotid arteries performed with elliptical ordering, fluoroscopic monitoring, and manual triggering.

Summary Background Gadoxetic acid (Gd-EOB-DTPA) is a ‘hepatocyte-specific’ contrast agent for magnetic resonance (MR) in both the vascular and the hepatobiliary phases. Aim To evaluate the contribution of the hepatobiliary phase of Gd-EOB-DTPA MR in the diagnosis of small hepatocellular carcinoma (HCC) in cirrhotic patients under surveillance. Methods Between 2008 and 2011, 48 consecutive small (10–30 mm) liver nodules were detected in 33 patients, who prospectively underwent contrast-enhanced ultrasound (CEUS), Gd-EOB-DTPA-enhanced MR and helical-computed tomography (CT) in a blind study. The diagnosis of HCC was established according to AASLD 2005 criteria. Results Of the 48 nodules, 38 (79%) were diagnosed as HCC, 24 (63%) of them based on AASLD non-invasive criteria, 11 diagnosed at histology and 3 during follow-up. The typical vascular pattern (arterial hypervascularisation and venous/late washout) was detected in 30 (79%) HCC nodules by MR, in 22 (58%) by CT and in 17 (45%) by CEUS. Hypointensity during the MR hepatobiliary phase was observed in all HCC nodules and in 3 nonmalignant nodules (sensitivity 100%, specificity 70%, positive predictive value 93%, negative predictive value 100%, positive likelihood ratio 3.33, negative likelihood ratio 0). Eight (21%) of the 38 HCC nodules, 7 of which lacked the typical vascular features at any of the imaging modalities, showed washout in the portal/venous phase and hypointensity in the hepatobiliary phase at MRI, while this pattern was not detected in any nonmalignant lesion. Conclusions Gadoxetic acid magnetic resonance may enhance the sensitivity of the non-invasive diagnosis of small hepatocellular carcinoma nodules in cirrhotic patients under surveillance. Double hypointensity in the portal/venous and hepatobiliary phases could be considered a new magnetic resonance pattern, highly suggestive of hypovascular hepatocellular carcinoma.

Purpose: To investigate whether the malignancy of atypical nodules in cirrhosis can be identified at gadoxeticacid- disodium(Gd-EOB-DTPA)-MRI by their hypointensity in the hepatobiliary(HB)-phase alone or combined with any other MR imaging features. Materials and Methods: One hundred eleven atypical nodules detected in 77 consecutive Gd-EOB-DTPA-MRIs were divided, based on arterial-phase behavior, into: Class I, isovascular (n ¼ 82), and Class II, hypervascular without portal/delayed washout (n ¼ 29). The two classes were further grouped based on HB-phase intensity (A/B/ C hypo/iso/hyperintensity). Portal/venous/equilibriumphase behavior and T2w features were also collected. Histology was the gold standard. Per-nodule sensitivity, specificity, negative and positive predictive values (NPV/PPV), and diagnostic accuracy were calculated for HB-phase hypointensity alone, and combined with vascular patterns and T2w hyperintensity. Results: Histology detected 60 benign and 51 malignant/ premalignant nodules [10 overt hepatocellular carcinomas (HCCs) and 41 high-grade dysplastic nodules (HGDN)/ early HCC]. Class IA contained 31 (94%) malignancies, IB one (3%), and IC only benign lesions. Class IIA had 100% malignancies, IIB three (37.5%) and IIC only two (28.5%). HB-phase hypointensity alone (Classes I–IIA) had 88% sensitivity, 91% NPV, and 93% diagnostic accuracy, superior (P < 0.05, P < 0.006, and P < 0.05, respectively) to any other MR imaging feature alone or combined. Conclusion: In atypical cirrhotic nodules, HB-phase hypointensity by itself is the strongest marker of malignancy.

Background Large regenerative nodules (LRNs) are hyperplastic benign nodules most commonly associated with Budd-Chiari syndrome (BCS), caused by outflow obstruction of the hepatic veins or vena cava. To our knowledge, no cases of LRNs arising in BCS after transjugular intrahepatic portosystemic shunt (TIPS) positioning and detected by Gd-EOB-DTPA MRI have been reported in the literature. Methods A 58-year-old woman with BCS, on the liver transplantation (LT) list, underwent a follow-up enhanced MRI. Two years earlier, a TIPS had been placed. In 2008, recurrent hepaticoencephalopathy resistant to medical treatment fulfilled the LT criteria for BCS treated with TIPS and the patient was therefore added to the LT list. CT performed before TIPS had not detected any hepatic lesions. CT performed six months after TIPS showed its complete patency but documented two indeterminate hypervascular liver lesions. Results MRI performed with Gd-EOB-DTPA revealed additional hypervascular lesions with uptake and retention of the medium in the hepatobiliary phase, thus refecting a benign behavior of hepatocellular composition. These MRI features were related to LRNs as confrmed by histopathologic analysis. Conclusions Gd-EOB-DTPA-enhanced MRI is potentially superior to standard imaging using gadolinium chelates or spiral CT, especially for the differential diagnosis of hypervascular lesions. Gd-EOB-DTPA MRI may become the imaging method of choice for evaluating LT list patients with BCS after TIPS placement.

A55 year-oldmanwith no known medical conditions or surgical history presented to our hospital to be evaluated as potential living liver donor. In our centre donor candidates are evaluated using a specific living donor protocol; this includes imaging studies for liver volumetrics (to quantify the amount of parenchyma that could be donated versus the remnant) and liver vascular anatomy, and magnetic resonance cholangiopancreatography (MRCP) to evaluate anatomy of the biliary tree. Computed tomography scanning was performed to estimate volume of the right and left lobes of the liver: the right lobe would be harvested for transplantation into the recipient, while the left would be the donor’s remnant liver; the test confirmed adequate volume of both liver lobes. MRCP showed biliary variants characterized by a right posterior hepatic duct (RPHD), which in classic biliary anatomy fuses with the right anterior duct to constitute a short right hepatic duct, draining directly into the common hepatic duct (CHD) (Fig. 1A, arrow). MRCP also showed that the cystic duct, which usually drains into the lateral aspect of the CHD below its origin, drained directly into theRPHDabove its confluence with theCHD(Fig. 1B, arrow). Classic biliary anatomy appears in about 58% of the population, while the variant in which RPHD drains directly into the CHD has a prevalence of approximately 5% [1]. These anatomical biliary variants are relevant in potential donors evaluated for living donor liver transplantation.

We investigate in vivo detection of mammary tumors in a rat model using autofluorescence imaging in the red and far-red spectral regions. The objective was to explore this method for non-invasive detection of malignant tumors and correlation between autofluorescence properties of tumors and their pathologic status. Eighteen tumor-bearing rats, bearing eight benign and seventeen malignant tumors were imaged. Autofluorescence images were acquired using spectral windows centered at 700-nm, 750-nm and 800-nm under laser excitation at 632.8-nm and 670- nm. Intensity in the autofluorescence images of malignant tumors under 670-nm excitation was higher than that of the adjacent normal tissue. whereas intensity of benign tumors was lower compared to normal tissue.

Objective: The objective of this study was to evaluate computed tomography (CT) enhancement characteristics for a new iodinated macromolecular contrast medium (MMCM), PEG12000-Gen4-triiodo, for angiographic effect and forassessment of abnormal vascular permeability in cancer. Materials and Methods: Time persistence of angiographic effect was evaluated on rat CT images acquired over 30 minutes using the iodinated polyethyleneglycol- (PEG) based macromolecule. Dynamic CT imaging after PEG12000-Gen4-triiodo-enhancement in tumor-bearing rats was used to quantitatively estimate plasma volume and microvascular transendothelial permeability for both tumor and normal soft tissue. Using identical doses of iodine, 300 mg iodine/kg, blood curves for this MMCM and iohexol were compared. Results: Serial whole-body CT angiograms using PEG12000-Gen4-triiodo showed diagnostic vascular detail through 20 minutes, and the blood enhancement curve was higher and more persistent than with small-molecular iohexol. Permeability estimates were significantly (P < 0.02; paired t test) higher in tumors (48.2 ′ 18.1 μL/min - 1 100 mL - 1 ) than in muscle (2.5 ′ 5.7 μL/min - 1 100 mL - 1 ). Conclusions: Use of PEG-based MMCM for experimental CT allowed for a persistent angiographic enhancement and for quantitative estimation of tumor microvascular characteristics.

The goal of this work is to highlight those unique aspects of contrast-enhanced diagnostic optical imaging (OI) that favor a broad clinical utilization of this emerging diagnostic technique and to illustrate certain identified challenges opposing the enthusiastic clinical welcome for the OI method. We consider the single most appealing feature of OI to be its much-touted exquisite sensitivity for the detection of near-infrared fluorescing (NIRF) probes, a sensitivity supporting the development of disease- and molecule-specific NIR diagnostic probes, akin to nuclear imaging but without the ionizing radiation and with superior spatial resolution. But a qualitative OI diagnostic examination, merely defining the presence or absence of NIRF signal, may not be sufficient. The signal must be measurable. A quantitative OI examination, capable of accurately assaying the tissue concentration of the fluorescing probe and changes in that probe concentration related to disease progression or treatment would be extremely valuable. We discuss here at least three challenges to quantitative diagnostic OI, a non-linear relationship between probe concentration and signal intensity, background signal in the form of tissue auto-fluorescence, and the requirement to define precise location and depth of the signal origin from within the subject.

This study was performed to evaluate the relationship between dose levels of contrast medium and image quality in magnetic resonance (MR) angiography of the carotid arteries with fluoroscopically monitored, manually triggered, elliptically ordered image acquisitions.Twenty-five patients with clinical indications for angiography of the carotid arteries were examined with MR at 1.5 T by using a fluoroscopically monitored, manually triggered, elliptically ordered pulse sequence with the administration of one of three different volumes of gadolinium-based contrast medium. The signal intensities of the vessel lumen and the surrounding tissues were measured in single partitions at the origin of the common carotid artery, the carotid bifurcation, and the intracranial internal carotid arteries. The contrast-to-noise ratio in these regions of interest also was measured. Maximum intensity projection image quality was appraised for blurring, artifacts, venous enhancement, background suppression, and contrast medium distribution.No artifacts or venous enhancement was observed. The position of the fluoroscopic section affected the distribution of contrast medium along the vessel, as evidenced by the difference between the contrast-to-noise ratio at the origin of the common carotid artery and the ratio at the carotid bifurcation and the intracranial internal carotid arteries (P.01). The contrast medium dose administered was strongly correlated with image quality (r = 0.90).Contrast medium dose is related to image quality in MR angiography of the carotid arteries performed with elliptical ordering, fluoroscopic monitoring, and manual triggering.

Benign and malignant mammary tumors were induced in rats using a potent carcinogen, N-ethyl-N-nitrosurea (ENU). Induced tumors were examined under near-infrared (NIR) fluorescence imaging (excitation wavelength 670-730 nm, detection wavelength 750-800 nm) to search for a difference in the photophysical properties of the tumors reflecting their pathologic status. Three benign and eight malignant tumors were examined optically and pathologically. The non-enhanced optical images showed a significantly lower (P

about the optical scattering coefficient of the tissue. As with endogenous optical imaging, time domain offers the potential to supersede CW for optical molecular imaging applications. The wealth of information contained in the fluorescence excitation and emission TPSFs permits the depth of the fluorophore to be obtained by even simple sonar-like approaches. Once the fluorophore depth is known, the intensity can be normalized to provide relative fluorophore concentration. In addition to the potential of TD to provide more accurate quantitative estimates of fluorophore depth and concentration than CW, TD enables the measurement of the fluoresence lifetime which CW is unable to provide. This permits the discrimination of fluorophores which may have significantly different fluoresence lifetimes, despite having similar emission spectra which challenges discrimination with intensity-based CW methods. Furthermore, it is known that the fluorescence lifetime can be influenced by the local environment of the fluorophore which provides additional physiological information. Time domain optical molecular imaging is the technological basis for the pre-clinical optical molecular imaging device (SAMITM) developed by ART.