The role of gadoxetic acid as a paramagnetic contrast medium in the characterization and detection of focal liver lesions: a review

Imaging prognostic biomarkers in hepatocellular carcinoma: a comprehensive review

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide with its incidence on the rise globally. This paper provides a comprehensive review of prognostic imaging markers in HCC, emphasizing their role in risk stratification and clinical decision-making. We explore quantitative and qualitative criteria derived from imaging studies, such as computed tomography and magnetic resonance imaging, which can offer valuable insights into the biological behavior of the tumor. While many of these markers are not yet widely integrated into current clinical guidelines, they represent a promising future direction for approaching this highly heterogeneous cancer. However, standardization and validation of these markers remain important challenges. We conclude by emphasizing the importance of ongoing research to enhance clinical practices and improve outcomes for patients with HCC.

No Cases of Nephrogenic Systemic Fibrosis after Administration of Gadoxetic Acid

Background Gadoxetic acid (GA) has distinctive pharmacokinetic properties with important applications in hepatobiliary imaging. However, there are limited data evaluating the safety of GA administration in patients with impaired kidney function and the incidence of nephrogenic systemic fibrosis (NSF). Purpose To evaluate safety of GA regarding risk of NSF in patients with impaired kidney function. Materials and Methods This retrospective study identified all GA-enhanced MRI (hereafter, GA MRI) examinations performed between July 2008 and December 2019 through a search of the electronic medical record. Serum creatinine values within 180 days or less of each GA MRI examination were retrieved and estimated glomerular filtration rate (eGFR) was calculated. The eGFR value nearest to each MRI examination was used. A separate search in the electronic medical record was also performed to identify patients with NSF. Dermatologists, nephrologists, and nephrologists at our institution were surveyed for any cases of NSF. In patients with NSF, all MRI examinations performed and contrast agents administered to these patients were recorded. Results Overall, 7820 GA MRI examinations were identified, performed in 5351 patients (3022 women and 2329 men). These included 299 examinations (242 patients) with eGFR of 30-44 mL/min/1.73 m² and 183 examinations (157 patients) with eGFR less than 30 mL/min/1.73 m². There were 109 examinations (in 94 patients) with eGFR of 15-29 mL/min/1.73 m², 40 examinations (in 39 patients) with eGFR less than 15 mL/min/1.73 m², and 34 examinations in 27 patients undergoing hemodialysis. Seventeen patients with eGFR less than 30 mL/min/1.73 m² or undergoing dialysis underwent GA MRI two or more times. Eighteen patients with biopsy-confirmed NSF were identified, none of whom were exposed to GA. The mean follow-up period for GA MRI examinations performed in patients with severe kidney impairment was 4.2 years (range, 0.2-11.3 years). Conclusion Gadoxetic acid may be safe with respect to nephrogenic systemic fibrosis in this patient population, although further studies are needed to confirm this. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Davenport and Shankar in this issue.

The value of morphofunctional magnetic resonance imaging with hepatospecific contrast agent in the characterization of hepatocellular carcinoma in a non-cirrhotic patient with hepatitis C

Hepatocellular carcinoma in patients with hepatitis C in the absence of cirrhosis is uncommon. We demonstrate the importance of morphofunctional magnetic resonance imaging (MRI) with a hepatospecific contrast agent by describing an asymptomatic female patient with HCV, who presented with a nodule detected on ultrasound. She underwent inconclusive computed tomography, presenting no signs of chronic liver disease. MRI with hepatospecific contrast providing functional information combined with the superior tissue contrast inherent to this method stands out for its greater accuracy with the possibility of not resorting to invasive diagnostic methods. With increasing experience and the dissemination of this new diagnostic modality in the medical field, its use and other potential benefits of morphofunctional MRI with hepatospecific contrast agents may be established, benefiting patients with challenging focal liver lesions.

Interstitial Lung Disease in Systemic Sclerosis: Focus on Early Detection and Intervention

Systemic sclerosis (SSc) is a progressive and often devastating disease characterized by autoimmune dysfunction, vasculopathy, and fibrosis. Interstitial lung disease (ILD) is identified in the majority of patients with SSc and is the leading cause of SSc-related mortality. Although clinical manifestations and ILD severity vary among patients, lung function typically declines to the greatest extent during the first 3-4 years after disease onset. We aim to provide an overview of SSc-associated ILD (SSc-ILD) with a focus on current and emerging tools for early diagnosis of ILD and current and novel treatments under investigation. Early detection of ILD provides the opportunity for early therapeutic intervention, which could improve patient outcomes. Thoracic high-resolution computed tomography is the most effective method of identifying ILD in patients with SSc; it enables detection of mild lung abnormalities and plays an important role in monitoring disease progression. Cyclophosphamide and mycophenolate mofetil are the most commonly prescribed treatments for SSc-ILD. Recently, nintedanib (an antifibrotic) was approved by the Food and Drug Administration for patients with SSc-ILD; it is indicated for slowing the rate of decline in pulmonary function. However, there is a need for additional effective and well-tolerated disease-modifying therapy. Ongoing studies are evaluating other antifibrotics and novel agents. We envision that early detection of lung involvement, combined with the emergence and integration of novel therapies, will lead to improved outcomes in patients with SSc-ILD.

Quantification of liver function by linearization of a two-compartment model of gadoxetic acid uptake using dynamic contrast-enhanced magnetic resonance imaging

Dynamic gadoxetic acid-enhanced magnetic resonance imaging (MRI) allows the investigation of liver function through the observation of the perfusion and uptake of contrast agent in the parenchyma. Voxel-by-voxel quantification of the contrast uptake rate (k₁ ) from dynamic gadoxetic acid-enhanced MRI through the standard dual-input, two-compartment model could be susceptible to overfitting of variance in the data. The aim of this study was to develop a linearized, but more robust, model. To evaluate the estimated k₁ values using this linearized analysis, high-temporal-resolution gadoxetic acid-enhanced MRI scans were obtained in 13 examinations, and k₁ maps were created using both models. Comparison of liver k₁ values estimated from the two methods produced a median correlation coefficient of 0.91 across the 12 scans that could be used. Temporally sparse clinical MRI data with gadoxetic acid uptake were also employed to create k₁ maps of 27 examinations using the linearized model. Of 20 scans, the created k₁ maps were compared with overall liver function as measured by indocyanine green (ICG) retention, and yielded a correlation coefficient of 0.72. In the 27 k₁ maps created via the linearized model, the mean liver k₁ value was 3.93 ± 1.79 mL/100 mL/min, consistent with previous studies. The results indicate that the linearized model provides a simple and robust method for the assessment of the rate of contrast uptake that can be applied to both high-temporal-resolution dynamic contrast-enhanced MRI and typical clinical multiphase MRI data, and that correlates well with the results of both two-compartment analysis and independent whole liver function measurements.

Infectious and Non-Infectious Diseases Causing the Air Crescent Sign: A State-of-the-Art Review

Aspergilloma, also known as mycetoma or fungus ball, is characterized by a round or oval mass with soft-tissue attenuation within a preexisting lung cavity. The typical computed tomography (CT) aspect of an aspergilloma is a mass separated from the wall of the cavity by an airspace of variable size and shape, resulting in the air crescent sign, also known as the meniscus sign. This CT feature is non-specific and can be simulated by several other entities that result in intracavitary masses. This review describes the main clinical and imaging aspects of the infectious and non-infectious diseases that may present with fungus-ball appearance, including pulmonary hydatid cyst, Rasmussen aneurysm, pulmonary gangrene, intracavitary clot, textiloma, lung cancer, metastasis, and teratoma, focusing on the differential diagnosis.

Comparison of the efficacy of Gd-EOB-DTPA-enhanced magnetic resonance imaging and magnetic resonance elastography in the detection and staging of hepatic fibrosis

The present study compared the efficacy of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and magnetic resonance elastography (MRE) in the estimation of hepatic fibrosis stages with histopathologic correlation.This retrospective study included 104 patients (87 men and 17 women; mean age, 60.6 ± 10.6 years) with chronic liver disease who underwent both Gd-EOB-DTPA-enhanced MRI and MRE. The relative enhancement (RE) ratio of the liver parenchyma and the contrast enhancement index (CEI) were calculated as (SIpostliver - SIpreliver)/SIpreliver and SIpost/SIpre, respectively, where SIpost and SIpre were the liver-to-muscle signal intensity ratios on the hepatobiliary phase images and noncontrast-enhanced images, respectively. The liver stiffness values were measured using MRE stiffness maps. The diagnostic performance of MRE, RE ratios, and CEI values for hepatic fibrosis staging were compared.The distribution of fibrosis stages was as follows: F0, n = 3 (2.9%); F1, n = 12 (11.5%); F2, n = 17 (16.3%); F3, n = 26 (25.0%); and F4, n = 46 (44.2%). MRE, RE ratios, and CEI values correlated significantly with hepatic fibrosis (rs = .79, -.35, -.25, respectively, P < .05). MRE showed a significantly higher diagnostic performance than did RE ratios and CEI values for each fibrosis stage, except while distinguishing the F1 fibrosis stage (CEI, P = .15). A cutoff value of RE ratio = 0.89 can be used to identify patients with significant hepatic fibrosis, with positive predictive value, sensitivity, specificity, and negative predictive value of 93.2%, 61.8%, 73.3%, and 24.4%, respectively.Gd-EOB-DTPA-enhanced MRI can potentially predict significant hepatic fibrosis. However, the diagnostic performance of MRE for hepatic fibrosis staging was superior to that of Gd-EOB-DTPA-enhanced MRI.

Metastatic pulmonary calcification: high-resolution computed tomography findings in 23 cases

Objective

The aim of this study was to evaluate the high-resolution computed tomography (HRCT) findings in patients diagnosed with metastatic pulmonary calcification (MPC).

Materials and Methods

We retrospectively reviewed the HRCT findings from 23 cases of MPC [14 men, 9 women; mean age, 54.3 (range, 26-89) years]. The patients were examined between 2000 and 2014 in nine tertiary hospitals in Brazil, Chile, and Canada. Diagnoses were established by histopathologic study in 18 patients and clinical-radiological correlation in 5 patients. Two chest radiologists analyzed the images and reached decisions by consensus.

Results

The predominant HRCT findings were centrilobular ground-glass nodules (n = 14; 60.9%), consolidation with high attenuation (n = 10; 43.5%), small dense nodules (n = 9; 39.1%), peripheral reticular opacities associated with small calcified nodules (n = 5; 21.7%), and ground-glass opacities without centrilobular ground-glass nodular opacity (n = 5; 21.7%). Vascular calcification within the chest wall was found in four cases and pleural effusion was observed in five cases. The abnormalities were bilateral in 21 cases.

Conclusion

MPC manifested with three main patterns on HRCT, most commonly centrilobular ground-glass nodules, often containing calcifications, followed by dense consolidation and small solid nodules, most of which were calcified. We also described another pattern of peripheral reticular opacities associated with small calcified nodules. These findings should suggest the diagnosis of MPC in the setting of hypercalcemia.

Magnetic resonance imaging of the cirrhotic liver: diagnosis of hepatocellular carcinoma and evaluation of response to treatment - Part 2

In the second part of this review, we will describe the ancillary imaging features of hepatocellular carcinoma (HCC) that can be seen on standard magnetic resonance imaging (MRI) protocol, and on novel and emerging protocols such as diffusion weighted imaging and utilization of hepatocyte-specific/hepatobiliary contrast agent. We will also describe the morphologic sub-types of HCC, and give a simplified non-invasive diagnostic algorithm for HCC, followed by a brief description of the liver imaging reporting and data system (LI-RADS), and MRI assessment of tumor response following locoregional therapy.

Evaluation of the indications for performing magnetic resonance imaging of the female pelvis at a referral center for cancer, according to the American College of Radiology criteria

Objective

To evaluate the indications for performing magnetic resonance imaging of the female pelvis at a referral center for cancer.

Materials and Methods

This was a retrospective, single-center study, conducted by reviewing medical records and imaging reports. We included 1060 female patients who underwent magnetic resonance imaging of the pelvis at a cancer center between January 2013 and June 2014. The indications for performing the examination were classified according to the American College of Radiology (ACR) criteria.

Results

The mean age of the patients was 52.6 ± 14.8 years, and 49.8% were perimenopausal or postmenopausal. The majority (63.9%) had a history of cancer, which was gynecologic in 29.5% and nongynecologic in 34.4%. Of the patients evaluated, 44.0% had clinical complaints, the most common being pelvic pain (in 11.5%) and bleeding (in 9.8%), and 34.7% of patients had previously had abnormal findings on ultrasound. Most (76.7%) of the patients met the criteria for undergoing magnetic resonance imaging, according to the ACR guidelines. The main indications were evaluation of tumor recurrence after surgical resection (in 25.9%); detection and staging of gynecologic neoplasms (in 23.3%); and evaluation of pelvic pain or of a mass (in 17.1%).

Conclusion

In the majority of the cases evaluated, magnetic resonance imaging was clearly indicated according to the ACR criteria. The main indication was local recurrence after surgical treatment of pelvic malignancies, which is consistent with the routine protocols at cancer centers.

Acquired portosystemic collaterals: anatomy and imaging

Portosystemic shunts are enlarged vessels that form collateral pathological pathways between the splanchnic circulation and the systemic circulation. Although their causes are multifactorial, portosystemic shunts all have one mechanism in common-increased portal venous pressure, which diverts the blood flow from the gastrointestinal tract to the systemic circulation. Congenital and acquired collateral pathways have both been described in the literature. The aim of this pictorial essay was to discuss the distinct anatomic and imaging features of portosystemic shunts, as well as to provide a robust method of differentiating between acquired portosystemic shunts and similar pathologies, through the use of illustrations and schematic drawings. Imaging of portosystemic shunts provides subclinical markers of increased portal venous pressure. Therefore, radiologists play a crucial role in the identification of portosystemic shunts. Early detection of portosystemic shunts can allow ample time to perform endovascular shunt operations, which can relieve portal hypertension and prevent acute or chronic complications in at-risk patient populations.

Abdominal vascular syndromes: characteristic imaging findings

Abdominal vascular syndromes are rare diseases. Although such syndromes vary widely in terms of symptoms and etiologies, certain imaging findings are characteristic. Depending on their etiology, they can be categorized as congenital-including blue rubber bleb nevus syndrome, Klippel-Trenaunay syndrome, and hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber syndrome)-or compressive-including "nutcracker" syndrome, median arcuate ligament syndrome, Cockett syndrome (also known as May-Thurner syndrome), and superior mesenteric artery syndrome. In this article, we aimed to illustrate imaging findings that are characteristic of these syndromes, through studies conducted at our institution, as well as to perform a brief review of the literature on this topic.

Changes seen on computed tomography of the chest in mildly symptomatic adult patients with sickle cell disease

OBJECTIVE

To describe and quantify the main changes seen on computed tomography of the chest in mildly symptomatic adult patients with sickle cell disease, as well as to evaluate the radiologist accuracy in determining the type of hemoglobinopathy.

MATERIALS AND METHODS

A prospective study involving 44 adult patients with sickle cell disease who underwent inspiration and expiration computed tomography of the chest. The frequency of tomography findings and the extent of involvement are reported. We also calculated radiologist accuracy in determining the type of hemoglobinopathy by analyzing the pulmonary alterations and morphology of the spleen.

RESULTS

The changes found on computed tomography scans, in descending order of frequency, were as follows: fibrotic opacities (81.8%); mosaic attenuation (56.8%); architectural distortion (31.8%); cardiomegaly (25.0%); lobar volume reduction (18.2%); and increased caliber of peripheral pulmonary arteries (9.1%). For most of the findings, the involvement was considered mild, five or fewer lung segments being affected. The accuracy in determining the type of hemoglobinopathy (HbSS group versus not HbSS group) was 72.7%.

CONCLUSION

In adult patients with sickle cell disease, the main tomography findings reflect fibrotic changes. In addition, computed tomography can be helpful in differentiating among hemoglobinopathies.