Objectives

To review the main aspects of the aortic repair, how to identify the principal different grafts and surgical techniques (open and endovascular) and recognize some common and uncommon complications and it mimickers.

Background

Aortic aneurysm is an abnormal dilatation of the aorta, carrying a substantial risk of rupture and thereby marked risk of death. The complication depends on patient vascular anatomy, extension and type of aneurysm, as can be related to procedure specific techniques.

Imaging findings OR Procedure findings

The uncomplicated aortic post operatory, showing how to differentiate between open surgical procedure and endovascular aneurysm repair (EVAR).

Differences on EVAR devices, with 3D reformation and schematic illustrations.

Analyzing some surgical complications, such as endoleak, infection, stent / coil migration, aneurysmal growth, pseudoaneurysm, signs of vulnerability and risk of rupture, fistulas and collections, occlusion / stenosis, aortic dissection, organ ischemia and other endovascular procedure specific complications.

Conclusion

Aortic aneurysms are a common vascular affection with a myriad of possible surgical treatments and outcomes. The importance of recognition of normal post operatory aspects and its complications relies on prognosis of the patient, implying on possible change of medical decision.

Objectives

To review imaging techniques, diagnosis and evaluation of gastrointestinal (GI) bleeding on computed tomography. CT may yield critical information regarding presence, location, and cause of active bleeding and therefore guide subsequent therapy.

Background

GI bleeding results in 300.000 hospital admissions annually in the United States with death rates approaching 40% in unstable patients. Peptic ulcer accounts for more than 50% of upper-GI bleeding, whereas colonic diverticulum and angioectasia are the most common causes of lower-GI bleeding. The type of diagnostic examination is dependent of many factors, including rate of bleeding, hemodynamic stability and complications. Evidence suggests that CT angiography (CTA) may be a useful diagnostic tool in the workup of patients presenting acute manifestations of upper or lower-GI bleeding, even reducing rates of negative endoscopy results.

Imaging findings OR Procedure findings

Active GI bleeding has many differential diagnoses. We will use different cases with CT multiplanar and angiographic reconstructions to illustrate these clinical conditions.

The preferred protocol is biphasic scanning after intravenous contrast injection, including arterial and venous phase. The diagnosis can be easily made if there is extravasation of contrast into the bowel lumen, intraluminal hematic collection or a jet of contrast that was not present on the non-enhanced scan.

Conclusion

Acute GI bleeding warrants expert clinical decision making and advanced diagnostic testing. CTA is a well-established modality that has the advantage of being readily available, noninvasive and fast, while providing information about related conditions.

Objectives

This exhibit aims at reviewing the imaging patterns that may allow to include primary or secondary neuroendocrine tumors (NETs) as a diagnostic possibility in the setting of suspicious liver lesions. Epidemiological and clinical features of such tumors will also be discussed. Finally, a case-based review illustrating the wide range of imaging patterns of presentation of primary and secondary NETs will be provided.

Background

NETs are a heterogeneous group of tumors with distinct morphological and biological manifestations. The liver is the main organ affected by metastases of NETs. Primary hepatic involvement, on the other hand, is extremely rare.

Imaging findings OR Procedure findings

Several imaging features of primary and secondary hepatic NETs may be found, such as single/multiple lesions, solid/ cystic lesions, hyper/ hypovascular enhancement, presence of calcifications etc.

Conclusion

Although the heterogeneity and non-specificity of imaging features of hepatic NETs may make it the diagnosis a challenge, awareness of the main imaging patterns may allow the radiologist to include NETs among the differential diagnoses of liver lesions in the appropriate clinical setting and to search for a possible extrahepatic primary site when metastases are suspected.

Objectives

This exhibit aims at:

a) Briefly reviewing the pharmacokinetic and pharmacodynamic properties of gadoxetate disodium and its clinical applications in liver imaging;

b) Discussing technical and imaging reading pitfalls and how to avoid them. A case-based review illustrating such points will be provided.

Background

Gadoxetic acid is a contrast agent that combines the properties of conventional extracellular gadolinium chelates (allowing hepatic arterial and portal venous phase imaging), as well as of liver-specific contrast agent (owing to delayed hepatocyte uptake in the hepatocellular phase, HCP). Gadoxetate disodium-enhanced MR imaging allows to improve the detection of liver lesions, define them as hepatocellular or nonhepatocellular, and also characterize some hepatocellular lesions, such as focal nodular hyperplasia (FNH).

Imaging findings OR Procedure findings

A range of pitfalls may be found when interpreting liver imaging in such a context: siderotic, steatotic and FNH nodules may mimic hepatocellular carcinomas; adenomas and areas of focal fat sparing may show enhancement on HCP; decreased/ absent hepatocellular uptake in fibrosis may limit liver evaluation, among many others. Such pitfalls (as well as tricks to avoid them) will be discussed.

Conclusion

Awareness of some very challenging pitfalls is of paramount importance when interpreting gadoxetate disodium-enhanced MR imaging of the liver, ultimately aiding the radiologist to reach an accurate diagnosis.

Objectives

To review the main aspects of different primary and secondary peritoneal pathologies, benign and malignant, and discuss some differential diagnosis of tumorlike lesions.

Background

The peritoneum is a thin serosal membrane that encases the peritoneal cavity, covering partially or completely abdominal and pelvic visceral organs and the abdominal walls.

In oncology, peritoneal involvement often determines prognosis and palliative treatment. Imaging methods (CT and MRI) helps to identify the main forms of presentation of peritoneal diseases and some oncological staging pitfalls (such as subcapsular or intrafissural hepatic lesions).

Besides that, it is possible to stage benign and infectious diseases, complications and consequences of abdominal surgical procedures.

Imaging findings OR Procedure findings

We will use several illustrative cases in order to demonstrate:

- primary peritoneal tumors, malignant such as desmoplastic small round cell tumor, or benign tumors such as multicystic mesothelioma.

- metastatic peritoneal disease (peritoneal carcinomatosis and pseudomyxoma peritonei), specially from gastrointestinal tract and ovary neoplasms.

- primary abdominal tumors that spread through the peritoneum, benign such as ovarian teratomas and uterine leiomyomas, or malignant such as lymphoma or gastrointestinal stromal tumors (GIST).

- infectious diseases like tuberculosis and hydatid cystic disease.

- miscellaneous conditions like calcifications related to peritoneal dialysis, spread of splenic tissue, plexiform neurofibroma, foreign body as gossypibomas and omental infarction.

Conclusion

Computed tomography and magnetic resonance imaging play an essential role on differentiating benign and malignant peritoneal pathologies. Knowing the peritoneal anatomy as well is essential for the radiologist.

Purpose

To retrospectively compare the intensity of wall enhancement (IWE) in different small bowel segments on MR-Enterography (MRE) when using a single dose (SD) or a double dose (DD) of gadolinium (Gd).

Material and methods

60 consecutive patients who underwent MRE exams and received a single dose (0.1 ml/Kg; n=30; 37.5 ± 14.9y; 53% male) or double dose (0.2 ml/Kg; n=30; 43.7 ± 15.5y; 53% male) of Gd were included. The IWE was assessed on single slices of four different small bowel segments (proximal and distal jejunum; proximal and distal ileum) by two blinded readers, both objectively (through a variation indicator considering the signal intensities on enteric phase in relation to the pre-contrast phase) and subjectively (through a scale ranging from 1, poor enhancement, to 4, good enhancement). P values were set at 0.10.

Results

The objective analysis revealed greater IWE just for the ileal segments in the DD group (p<0.10). On subjective analysis, DD have determined greater IWE for all segments (p<0.05).

Conclusion

The present study demonstrates that DD administration of Gd has led to greater conspicuity of bowel wall enhancement on the subjective analyses, which has practical implications on a daily clinical practice scenario (in which objective signal intensity measurements are not routinely performed). This impression was also confirmed in the objective analyses of the ileal segment (most commonly affected in Crohn’s disease, for example, and an important segment of interest in MRE evaluations).

Purpose

There is scarce published data on the MR imaging features of autoimmune hepatitis (AIH) and their frequency; moreover, no previous study has assessed the repeatability of such findings. Our purpose was to determine the frequency and interobserver reproducibility of the MR diagnostic features for AIH.

Material and methods

Two abdominal radiologists, blinded to pathology data, reviewed MRI exams of 20 patients with a confirmed diagnosis of AIH for the presence of patchy or heterogeneous liver enhancement, lymphadenopathy, findings of portal hypertension, chronic liver disease and its complications. Hepatic fibrosis was graded as reticular (mild, moderate or severe), or confluent. Inter-reader agreement was assessed through intraclass correlation coefficients and κ statistics.

Results

The most common abnormal finding was surface nodularity (85%), liver reticular fibrosis (80%) [mild (25%), moderate (43.8%), severe (31.2%)], heterogeneous enhancement (65%), splenomegaly (60%), caudate lobe enlargement (50%) and lymphadenopathy (40%). Overall inter-reader agreement was almost perfect for surface nodularity (0.83), ascites (0.89) and hepatic volume (0.95); however, it was just slight (0.12) and fair (0.25) for fibrosis degree and heterogeneous liver enhancement, respectively. It was also slight (0.14) or fair (0.36) for findings of chronic liver disease, such as expanded gallbladder fossa and enlarged preportal space, respectively.

Conclusion

Overall inter-reader agreement was satisfactory for surface nodularity (the most prevalent abnormal finding), ascites, hepatic volume and splenomegaly. Conversely, frequent but less objective criteria had only slight to fair inter-reader agreement. Further studies are necessary to establish more consistent and reproducible criteria for assessing the morphological changes inherent to AIH on MRI.

Objectives

This exhibit aims at reviewing the imaging patterns that may allow to include primary or secondary neuroendocrine tumors (NETs) as a diagnostic possibility in the setting of suspicious liver lesions. Epidemiological and clinical features of such tumors will also be discussed. Finally, a case-based review illustrating the wide range of imaging patterns of presentation of primary and secondary NETs will be provided.

Background

NETs are a heterogeneous group of tumors with distinct morphological and biological manifestations. The liver is the main organ affected by metastases of NETs. Primary hepatic involvement, on the other hand, is extremely rare.

Imaging findings OR Procedure findings

Several imaging features of primary and secondary hepatic NETs may be found, such as single/multiple lesions, solid/ cystic lesions, hyper/ hypovascular enhancement, presence of calcifications etc.

Conclusion

Although the heterogeneity and non-specificity of imaging features of hepatic NETs may make it the diagnosis a challenge, awareness of the main imaging patterns may allow the radiologist to include NETs among the differential diagnoses of liver lesions in the appropriate clinical setting and to search for a possible extrahepatic primary site when metastases are suspected.

Objectives

This exhibit aims at:

a) Briefly reviewing the pharmacokinetic and pharmacodynamic properties of gadoxetate disodium and its clinical applications in liver imaging;

b) Discussing technical and imaging reading pitfalls and how to avoid them. A case-based review illustrating such points will be provided.

Background

Gadoxetic acid is a contrast agent that combines the properties of conventional extracellular gadolinium chelates (allowing hepatic arterial and portal venous phase imaging), as well as of liver-specific contrast agent (owing to delayed hepatocyte uptake in the hepatocellular phase, HCP). Gadoxetate disodium-enhanced MR imaging allows to improve the detection of liver lesions, define them as hepatocellular or nonhepatocellular, and also characterize some hepatocellular lesions, such as focal nodular hyperplasia (FNH).

Imaging findings OR Procedure findings

A range of pitfalls may be found when interpreting liver imaging in such a context: siderotic, steatotic and FNH nodules may mimic hepatocellular carcinomas; adenomas and areas of focal fat sparing may show enhancement on HCP; decreased/ absent hepatocellular uptake in fibrosis may limit liver evaluation, among many others. Such pitfalls (as well as tricks to avoid them) will be discussed.

Conclusion

Awareness of some very challenging pitfalls is of paramount importance when interpreting gadoxetate disodium-enhanced MR imaging of the liver, ultimately aiding the radiologist to reach an accurate diagnosis.

Purpose

To retrospectively compare the intensity of wall enhancement (IWE) in different small bowel segments on MR-Enterography (MRE) when using a single dose (SD) or a double dose (DD) of gadolinium (Gd).

Material and methods

60 consecutive patients who underwent MRE exams and received a single dose (0.1 ml/Kg; n=30; 37.5 ± 14.9y; 53% male) or double dose (0.2 ml/Kg; n=30; 43.7 ± 15.5y; 53% male) of Gd were included. The IWE was assessed on single slices of four different small bowel segments (proximal and distal jejunum; proximal and distal ileum) by two blinded readers, both objectively (through a variation indicator considering the signal intensities on enteric phase in relation to the pre-contrast phase) and subjectively (through a scale ranging from 1, poor enhancement, to 4, good enhancement). P values were set at 0.10.

Results

The objective analysis revealed greater IWE just for the ileal segments in the DD group (p<0.10). On subjective analysis, DD have determined greater IWE for all segments (p<0.05).

Conclusion

The present study demonstrates that DD administration of Gd has led to greater conspicuity of bowel wall enhancement on the subjective analyses, which has practical implications on a daily clinical practice scenario (in which objective signal intensity measurements are not routinely performed). This impression was also confirmed in the objective analyses of the ileal segment (most commonly affected in Crohn’s disease, for example, and an important segment of interest in MRE evaluations).

Purpose

There is scarce published data on the MR imaging features of autoimmune hepatitis (AIH) and their frequency; moreover, no previous study has assessed the repeatability of such findings. Our purpose was to determine the frequency and interobserver reproducibility of the MR diagnostic features for AIH.

Material and methods

Two abdominal radiologists, blinded to pathology data, reviewed MRI exams of 20 patients with a confirmed diagnosis of AIH for the presence of patchy or heterogeneous liver enhancement, lymphadenopathy, findings of portal hypertension, chronic liver disease and its complications. Hepatic fibrosis was graded as reticular (mild, moderate or severe), or confluent. Inter-reader agreement was assessed through intraclass correlation coefficients and κ statistics.

Results

The most common abnormal finding was surface nodularity (85%), liver reticular fibrosis (80%) [mild (25%), moderate (43.8%), severe (31.2%)], heterogeneous enhancement (65%), splenomegaly (60%), caudate lobe enlargement (50%) and lymphadenopathy (40%). Overall inter-reader agreement was almost perfect for surface nodularity (0.83), ascites (0.89) and hepatic volume (0.95); however, it was just slight (0.12) and fair (0.25) for fibrosis degree and heterogeneous liver enhancement, respectively. It was also slight (0.14) or fair (0.36) for findings of chronic liver disease, such as expanded gallbladder fossa and enlarged preportal space, respectively.

Conclusion

Overall inter-reader agreement was satisfactory for surface nodularity (the most prevalent abnormal finding), ascites, hepatic volume and splenomegaly. Conversely, frequent but less objective criteria had only slight to fair inter-reader agreement. Further studies are necessary to establish more consistent and reproducible criteria for assessing the morphological changes inherent to AIH on MRI.