Safe and Informed Use of Gadolinium-Based Contrast Agent in Body Magnetic Resonance Imaging: Where We Were and Where We Are

Gadolinium-based contrast agents (GBCAs) have helped to improve the role of magnetic resonance imaging (MRI) for the diagnosis and treatment of diseases. There are currently nine different commercially available gadolinium-based contrast agents (GBCAs) that can be used for body MRI cases, and which are classifiable according to their structures (cyclic or linear) or biodistribution (extracellular-space agents, target/specific-agents, and blood-pool agents). The aim of this review is to illustrate the commercially available MRI contrast agents, their effect on imaging, and adverse reaction on the body, with the goal to lead to their proper selection in different clinical contexts. When we have to choose between the different GBCAs, we have to consider several factors: (1) safety and clinical impact; (2) biodistribution and diagnostic application; (3) higher relaxivity and better lesion detection; (4) higher stability and lower tissue deposit; (5) gadolinium dose/concentration and lower volume injection; (6) pulse sequences and protocol optimization; (7) higher contrast-to-noise ratio at 3.0 T than at 1.5 T. Knowing the patient's clinical information, the relevant GBCAs properties and their effect on body MRI sequences are the key features to perform efficient and high-quality MRI examination.

Abdominal compartment syndrome: what radiologist needs to know

The intra-abdominal hypertension (IAH) and the abdominal compartment syndrome (ACS) are life-threatening conditions with a significant rate of mortality; therefore, early detection is paramount in their optimal management. IAH is diagnosed when the intra-abdominal pressure (IAP) is more than 12 mmHg. It can occur when the intra-abdominal volume increases (ileus, ascites, trauma, pancreatitis, etc.) and/or the abdominal wall compliance decreases. IAH can cause decreased venous flow, low cardiac output, renal impairment, and decreased respiratory compliance. Consequently, these complications can lead to multiple organ failure and induce the abdominal compartment syndrome (ACS) when IAP rises above 20 mmHg. The diagnosis is usually made with intravesical pressure measurement. However, this measurement was not always possible to obtain; therefore, alternative diagnostic techniques should be considered. In this setting, computed tomography (CT) may play a crucial role, allowing the detection and characterization of pathological conditions that may lead to IAH. This review is focused on the pathogenesis, clinical features, and radiological findings of ACS, because their presence allows radiologists to raise the suspicion of IAH/ACS in critically ill patients, guiding the most appropriate treatment.

Hepatobiliary-specific magnetic resonance contrast agents: role in biliary trauma

Non-iatrogenic traumatic bile duct injuries (NI-TBIs) are a rare complication after abdominal trauma, with an estimated prevalence of 2.8-7.4% in patients underwent blunt liver injuries. They may be overlooked in patients with extensive multi-organ trauma, particularly hepatic, splenic and duodenal injuries, which have a prevalence of 91%, 54% and 54%, respectively. Whole body contrast-enhanced computed tomography (CE-CT) represents the examination of choice in polytraumatized hemodynamically stable patients, as it allows a comprehensive evaluation of vascular, parenchymal, bone and soft tissues injuries, but the diagnosis of any biliary leaks is limited to the evaluation of nonspecific imaging findings and on findings evolution in the follow-up, such as the progressive growth of fluid collections. Furthermore, biliary complications, such as the occurrence of biloma or biliary peritonitis, may become manifest several days after the initial trauma, often with unspecific progressive signs and symptoms. Although CT and ultrasonography can suggest bile leaks based on several nonspecific imaging findings (e.g., fluid collections), magnetic resonance imaging (MRI) using hepatobiliary contrast agents helps to identify the site and entity of post-traumatic biliary disruption. Indeed, MRI allows to obtain cholangiographic sequences that may show post-traumatic active bile leakage and cysto-biliary communications by direct visualisation of contrast material extravasation into fluid collections, increasing the preoperative accuracy of NI-TBIs. Few data are available about MRI use in the follow-up of trauma with NI-TBI management. So, in the present mini review, its role is reviewed and our preliminary experience in this field is reported.

MRI-Cavernosography: A New Diagnostic Tool for Erectile Dysfunction Due to Venous Leakage: A Diagnostic Chance

Erectile dysfunction caused by venous leakage is a vascular disease in which blood fails to accumulate in the corpora cavernosa due to the abrupt drainage of blood from the penis secondary to an abnormal venous network that affects 1 to 2% of men under 25 years old and about 10 to 20% over 60 years old, who do not raise a sufficient erection for penetrative sex. The study of the venous leak and its characterization in young patients with erectile dysfunction represent a diagnostic challenge, and imaging remains the best way to diagnose this condition. In the article, it is described the methods of execution and the diagnostic role of the cavernous MRI in the study of vasogenic erectile dysfunction from the venous leak, proposing it as a good alternative to the cavernous CT, considering the satisfactory results in terms of diagnostic interpretation, the absence of ionizing radiation, the higher soft tissue resolution of the imaging method and the lower administration of contrast agent.

An update on pyelonephritis: role of contrast enhancement ultrasound (CEUS)

Acute pyelonephritis (APN) is a bacterial infection causing inflammation of the kidneys. Diagnosis is usually based on clinical and laboratory findings. Imaging is required if a complication is suspected in acute pyelonephritis to assess the nature and extent of the lesions and to detect underlying causes. CT represents the current imaging modality of choice in clinical practice. CEUS is an alternative that has been proven to be equally accurate in the detection of acute pyelonephritis renal lesions. CEUS allows us to distinguish small simple nephritic involvement from abscess complications and to follow their evolution over time during antibiotic therapy. The absence of ionizing radiation and the lack of nephrotoxicity make CEUS an ideal tool in the study of pyelonephritis.

Non-Operative Management of Polytraumatized Patients: Body Imaging beyond CT

In the transition from the operative to the conservative approach for the polytraumatized patients who undergo blunt trauma, diagnostic imaging has assumed a pivotal role, currently offering various opportunities, particularly in the follow-up of these patients. The choice of the most suitable imaging method in this setting mainly depends on the injury complications we are looking for, the patient conditions (mobilization, cooperation, medications, allergies and age), the biological invasiveness, and the availability of each imaging method. Computed Tomography (CT) represents the “standard” imaging technique in the polytraumatized patient due to the high diagnostic performance when a correct imaging protocol is adopted, despite suffering from invasiveness due to radiation dose and intravenous contrast agent administration. Ultrasound (US) is a readily available technology, cheap, bedside performable and integrable with intravenous contrast agent (Contrast enhanced US—CEUS) to enhance the diagnostic performance, but it may suffer particularly from limited panoramicity and operator dependance. Magnetic Resonance (MR), until now, has been adopted in specific contexts, such as biliopancreatic injuries, but in recent experiences, it showed a great potential in the follow-up of polytraumatized patients; however, its availability may be limited in some context, and there are specific contraindications, such as as claustrophobia and the presence non-MR compatible devices. In this article, the role of each imaging method in the body-imaging follow-up of adult polytraumatized patients will be reviewed, enhancing the value of integrated imaging, as shown in several cases from our experience.

Multimodality ultrasound assessment of the spleen: Normal appearances and emergency abnormalities

This paper summarizes the main splenic emergencies and their ultrasonographic findings to orient appropriate patient management. US requires minimal preparation time and allows to examine the parenchyma and to detect intraperitoneal fluid collections, which may be indirect evidence of solid organ injuries. In this paper, we analyze the role of B-mode, Doppler and Contrast-Enhanced Ultrasound in the diagnosis of splenic emergencies, with a particular focus on splenic infarction, infection, traumatic injuries and vascular splenic anomalies.

Ultrasound of scrotal and penile emergency: how, why and when

High-resolution ultrasound is the most common imaging technique used to supplement the physical examination of scrotum and penis with great accuracy in assisting the diagnosis of the various pathologies of male genital system, with the highest diagnostic potential in emergency conditions. Technical advancements in real-time high-resolution, color flow Doppler sonography and contrast enhanced ultrasonography (CEUS) have led to an increase in the clinical applications of scrotal and penile sonography. In this pictorial review we focus on common and uncommon male genitalia emergency with special emphasis on the role of ultrasound assessment and its specific findings to improve diagnostic accuracy.

"Tethered Fat Sign": The Sonographic Sign of Omental Infarction

Our purpose is to describe the ultrasound sign for a correct non-invasive diagnosis of omental infarction in children. From January 2014 to December 2018, a total of 234 children (109 boys and 125 girls, age range 3-15 y) with acute right-sided abdominal pain, admitted to our hospital with a presumptive diagnosis of acute appendicitis, were prospectively evaluated. In all patients, abdominal ultrasound was performed, and the omental fat was always evaluated. In 228 patients, the omental fat resulted to be normal or hyperechogenic, never tethered, and they results affected by other causes of abdominal pain different from omental infarction (such as appendicitis, pancreatitis, urolithiasis and others). In the remaining 6 children, we found a hyperechoic mass between the anterior abdominal wall and the ascending or transverse colon in the right abdomen quadrant, suggesting the diagnosis of omental infarction. This subhepatic mass was always tethered to the abdominal wall, motionless during respiratory excursions. We named this finding the "tethered fat sign." The diagnosis was confirmed with laparoscopy in 4 children. The other 2 children were treated with conservative therapy. In these 2 patients, a sonographic follow-up was performed, showing a progressive reduction in size of the right-sided hyperechoic mass. In conclusion, our study suggests that the presence of the "tethered fat sign" may be an accurate sonographic sign for non-invasive diagnosis of omental infarction in children.