Unusual hemodynamics and pseudolesions of the noncirrhotic liver at CT

Liver Pseudotumor Due to Aberrant Left Gastric Vein: A Case Report

Liver pseudotumors (pseudolesions) pose diagnostic challenges in imaging, often linked to anomalous venous drainage. Notably, aberrant left gastric vein (ALGV) plays a role in segment 2 and 3 pseudolesions. A liver parenchymal pseudolesion due to abnormal venous drainage involving ALGV is highlighted. Understanding hepatic vascular dynamics, exemplified by ALGV-related pseudolesions, aids diagnosis and guides decisions. Further investigating intricate mechanisms underlying these anomalies is crucial.

Teaching Point

The recognition of third inflow pathways such as ALGV holds significance in distinguishing hepatic pseudolesions from true lesions.

Surgical Anatomy of the Liver-Significance in Ovarian Cancer Surgery

INTRODUCTION

Ovarian cancer is the leading cause of death among all gynecological malignancies. Most patients present with an advanced stage of the disease. The routes of spread in ovarian cancer include peritoneal dissemination, direct invasion, and lymphatic or hematogenous spread, with peritoneal and lymphatic spread being the most common among them. The flow direction of the peritoneal fluid makes the right subphrenic space a target site for peritoneal metastases, and the most frequently affected anatomical area in advanced cases is the right upper quadrant. Complete cytoreduction with no macroscopically visible disease is the most important prognostic factor.

METHODS

We reviewed published clinical anatomy reports associated with surgery of the liver in cases of advanced ovarian cancer.

RESULTS

The disease could disseminate anatomical areas, where complex surgery is required-Morrison's pouch, the liver surface, or porta hepatis. The aim of the present article is to emphasize and delineate the gross anatomy of the liver and its surgical application for oncogynecologists. Moreover, the association between the gross and microscopic anatomy of the liver is discussed. Additionally, the vascular supply and variations of the liver are clearly described.

CONCLUSIONS

Oncogynecologists performing liver mobilization, diaphragmatic stripping, and porta hepatis dissection must have a thorough knowledge of liver anatomy, including morphology, variations, functional status, potential diagnostic imaging mistakes, and anatomical limits of dissection.

Artificial intelligence-powered software detected more than half of the liver metastases overlooked by radiologists on contrast-enhanced CT

PURPOSE

To evaluate the sensitivity of artificial intelligence (AI)-powered software in detecting liver metastases, especially those overlooked by radiologists.

METHODS

Records of 746 patients diagnosed with liver metastases (November 2010-September 2017) were reviewed. Images from when radiologists first diagnosed liver metastases were reviewed, and prior contrast-enhanced CT (CECT) images were checked for availability. Two abdominal radiologists classified the lesions into overlooked lesions (all metastases missed by radiologists on prior CECT) and detected lesions (all metastases if any of them were correctly identified and invisible on prior CECT or those with no prior CECT). Finally, images from 137 patients were identified, 68 of which were classified as "overlooked cases." The same radiologists created the ground truth for these lesions and compared them with the software's output at 2-month intervals. The primary endpoint was the sensitivity in detecting all liver lesion types, liver metastases, and liver metastases overlooked by radiologists.

RESULTS

The software successfully processed images from 135 patients. The per-lesion sensitivity for all liver lesion types, liver metastases, and liver metastases overlooked by radiologists was 70.1%, 70.8%, and 55.0%, respectively. The software detected liver metastases in 92.7% and 53.7% of patients in detected and overlooked cases, respectively. The average number of false positives was 0.48 per patient.

CONCLUSION

The AI-powered software detected more than half of liver metastases overlooked by radiologists while maintaining a relatively low number of false positives. Our results suggest the potential of AI-powered software in reducing the frequency of overlooked liver metastases when used in conjunction with the radiologists' clinical interpretation.

Lobar hepatic steatosis: Association with portal flow hemodynamics evaluated by multiphasic dynamic contrast-enhanced CT

PURPOSE

This study aimed to evaluate the association of portal flow hemodynamics with lobar hepatic steatosis by means of dynamic contrast-enhanced (DCE) CT.

METHODS

The study population consisted of 235 patients, 77 with lobar hepatic steatosis (right, n = 67; left, n = 10), 158 with diffuse hepatic steatosis with (n = 76) and without (n = 82) a focal fatty spared area. CT attenuation values (Hounsfield units: HU) of the liver with and without hepatic steatosis were measured in unenhanced and arterial-phase CT. The contrast enhancement (CE) values were calculated as the difference in HU values between unenhanced and arterial-phase CT.

RESULTS

In 67 patients with lobar steatosis of the right lobe, the median CE values of the areas of right lobar steatosis were significantly lower than those of the non-fatty left lobe (13 [IQR 7-19] vs 23 [13-33] HU, P < 0.01), suggesting dominant SMV flow to the right lobe with lobar hepatic steatosis. Conversely, in 10 patients with lobar steatosis of the left lobe, the median CE values of the areas of left lobar steatosis were lower than those of the non-fatty right lobe (15.5 [11.75-21.5] vs 16 [14.5-22] HU); however, this difference was not statistically significant (P = 0.20). In 76 patients with a focal fatty spared area, there were significant differences in the median CE values between hepatic steatosis areas and focal fatty spared areas in the gallbladder fossa group (P = 0.01) and in the segment IV group (P < 0.01).

CONCLUSION

Lobar hepatic steatosis may be associated with regional changes of the portal flow hemodynamics (i.e., predominant perfusion from the SMV flow to the lobes with steatosis).

Lesion or Pseudolesion? A Comprehensive Description of Perfusion-Based Liver Alterations on Contrast-Enhanced Computed Tomography and Literature Review

ABSTRACT

Pseudolesions on contrast-enhanced computed tomography represent a diagnostic challenge for radiologists because they could be difficult to distinguish from true space-occupying lesions. This article aims to provide a detailed overview of these entities based on radiological criteria (hyperattenuation or hypoattenuation, localization, morphology), as well as a brief review of the hepatic vascular anatomy and pathophysiological process. Relevant examples from hospital case series are reported as helpful hints to assist radiologists in recognizing and correctly diagnosing these abnormalities.

Falciform ligament abscess with disseminated intrahepatic foci: a case report

Background

Falciform ligament abscess (FLA) is a rare disease, and its diagnosis can be challenging without typical image findings of an abscess. We report a patient with FLA that presented as a mass, with an indistinct border between it and the liver, in addition to disseminated foci within the liver. This made it difficult to determine whether it was FLA or a malignancy.

Case presentation

A 69-year-old man presented with epigastric pain. Contrast-enhanced computed tomography revealed a 25-mm mass below the middle of the diaphragm. Based on an initial diagnosis of infection of the falciform ligament, we administered conservative antibiotic treatment and there was initial improvement in the patient’s clinical condition and laboratory data. However, he continued to experience mild epigastric pain. A month later, imaging studies revealed enlargement of the falciform ligament mass and the emergence of a new nodule in the liver, whereas laboratory findings showed re-elevated C-reactive protein levels. Since conservative treatment had failed, we decided to perform surgery. Considering the imaging study findings, malignant disease could not be ruled out. Based on the operative findings, we performed combined resection of the falciform ligament, left liver, and gallbladder. Histopathological examination of the resected specimens revealed extensive neutrophil infiltration and the presence of giant cells and foam cells within the lesions. These findings were indicative of abscess. Pseudomonas aeruginosa was cultured from the pus in the falciform ligament mass and bile in the gallbladder. Although multiple abscesses postoperatively developed in the residual portion of the liver, they could be treated through antibiotic therapy.

Conclusions

FLA can spread to both adjacent and distant organs via its rich vascular and lymphatic networks. When FLA displays atypical image findings and/or an atypical clinical course, it can be difficult to distinguish it from malignant disease. In such cases, surgical treatment, with intraoperative pathological diagnosis, should be attempted.

Hepatic pseudolesions caused by alterations in intrahepatic hemodynamics

Hepatic pseudolesion may occur in contrast-enhanced computed tomography and magnetic resonance imaging due to the unique haemodynamic characteristics of the liver. The concept of hepatic arterial buffer response (HABR) has become mainstream for the understanding of the mechanism of the reciprocal effect between hepatic arterial and portal venous flow. And HABR is thought to be significantly related to the occurrence of the abnormal imaging findings on arterial phase of contrast enhanced images, such as hepatic arterial-portal vein shunt and transient hepatic attenuation difference, which mimic hypervascular tumor and may cause clinical problems. Third inflow to the liver also cause hepatic pseudolesion, and some of the cases may show histopathologic change such as focal hyperplasia, focal fatty liver, and focal sparing of fatty liver, and called pseudotumor. To understand these phenomena might be valuable for interpreting the liver imaging findings.

Imaging of the chemotherapy-induced hepatic damage: Yellow liver, blue liver, and pseudocirrhosis

The liver is the major drug-metabolizing and drug-detoxifying organ. Many drugs can cause liver damage through various mechanisms; however, the liver response to injury includes a relatively narrow spectrum of alterations that, regardless of the cause, are represented by phlogosis, oxidative stress and necrosis. The combination of these alterations mainly results in three radiological findings: vascular alterations, structural changes and metabolic function reduction. Chemotherapy has changed in recent decades in terms of the drugs, protocols and duration, allowing patients a longer life expectancy. As a consequence, we are currently observing an increase in chemotherapy-associated liver injury patterns once considered unusual. Recognizing this form of damage in an early stage is crucial for reconsidering the therapy regimen and thus avoiding severe complications. In this frontier article, we analyze the role of imaging in detecting some of these pathological patterns, such as pseudocirrhosis, “yellow liver” due to chemotherapy-associated steatosis-steatohepatitis, and “blue liver”, including sinusoidal obstruction syndrome, veno-occlusive disease and peliosis.

Unveiling the unreal: Comprehensive imaging review of hepatic pseudolesions

Hepatic pseudolesions are defined as non-neoplastic focal abnormalities of the liver which can mimic or conceal true liver lesions. It is particularly common in liver due to its unique dual blood supply and the existence of multilevel anastomosis between them. Because of the recent advances in CT and MRI technology, they are being increasingly encountered in daily practice. Broadly they can be categorised in to (1) Focal parenchymal abnormalities like focal fatty change, focal fat sparing, focal confluent fibrosis, segmental hypertrophy and regenerative nodules, (2) Perfusion abnormalities which include transient hepatic parenchymal enhancement in portal vein obstruction, third inflow, intrahepatic shunts, hepatic arterial occlusion and hepatic venous obstruction, (3) Imaging pitfalls like parenchymal compression, unenhanced vessels and pseudolipoma. It is essential for the radiologists to be familiar with the typical and atypical imaging features of pseudolesions to avoid mistaking them for sinister pathologies and also to avoid overlooking underlying hidden pathologies.

Hemodynamic changes of abdominal organs after CT colonography with transrectal administration of CO2: evaluation with early-phase contrast-enhanced dynamic CT

PURPOSE

To evaluate the hemodynamic changes in the liver, pancreas, gastric mucosa and abdominal vessels in early-phase dynamic contrast-enhanced (DCE) CT immediately after CT colonography (CTC) with carbon dioxide expansion.

MATERIALS AND METHODS

This study included 82 patients with DCE-CT after CTC (CTC group) and 77 patients without CTC (control group). Contrast enhancement values of the gastric mucosa, liver, pancreas, portal vein (PV), splenic vein (SpV), superior mesenteric vein (SMV), and inferior mesenteric vein (IMV) in early-phase CT were measured. The presence of hepatic pseudolesions were also recorded.

RESULTS

The mean contrast enhancement values of the gastric mucosa, pancreas and SpV in the CE-CTC group were significantly lower than those in the control group (p < 0.001, p < 0.001, p = 0.014). Conversely, the mean contrast enhancement values of the liver, PV, SMV and IMV in the CE-CTC group were significantly higher than those in the control group (p = 0.003, p = 0.013, p < 0.001, p < 0.001). Hypovascular hepatic pseudolesions were seen in early-phase CT in six patients after CTC, while they were not seen in the control group.

CONCLUSIONS

On DCE-CT performed immediately after CTC with carbon dioxide expansion, it is important to be aware of the imaging findings induced by visceral hemodynamic changes.

A 3D-printed Apparatus for Imaging Multiple Rats Simultaneously

CT (computerized tomography) is a necessary imaging modality for cancer staging and disease monitoring. Rodent models of cancer are commonly studied prior to human clinical trials, but CT in rodents can be difficult due to their small size and constant movement, which necessitates general anesthesia. Because microCT equipment is not always available, clinical CT may be a viable alternative. Limitations of microCT and clinical CT include biosecurity, anesthesia to limit image distortion due to motion, and cost. To address several of these constraints, we created a 3D-printed apparatus that accommodated simultaneous imaging of as many as 9 rats under gas anesthesia. Rats were anesthetized in series and placed in a 3 × 3 arrangement. To assess differences in attenuation between individual chambers and rows or columns in the device, we first imaged a standardized phantom plug as a control. We hypothesized that attenuation of specific rat organs would not be affected regardless of the location or position in the 3D-printed device. Four organs-liver, kidney, femur, and brain-were evaluated in 9 rats. For both the phantom and kidneys, statistically significant, but clinically negligible, effects on attenuation were noted between rows but not between columns. We attribute this finding to the absence of a top layer of the apparatus, which thus created asymmetric attenuation and beam hardening through the device. This apparatus allowed us to successfully image 9 rats simultaneously in a clinical CT machine, with negligible effects on attenuation. Planned improvements in this apparatus include completely enclosed versions for biosecure imaging.

Vascular disorders of the gallbladder and bile ducts: Imaging findings

Vascular disorders of the gallbladder and biliary tree are many and varied. In the acute setting, the clinical presentation of vascular conditions such as hemorrhagic cholecystitis and gangrenous cholecystitis are non-specific and rely on imaging for diagnosis and triaging for emergent surgery. These hemorrhagic and ischemic complications of acute cholecystitis are uncommon but potentially fatal. Hemorrhage into the gallbladder and biliary tree, from other causes, may itself result in acute cholecystitis. Knowledge of vascular anatomy of the gallbladder and biliary tree is essential for surgeons to prevent significant operative bleeding complications, particularly in laparoscopic cholecystectomy. The unique venous drainage of the gallbladder and biliary tree, with their connections to the portal venous system, lends itself to less well-recognised vascular phenomena such as gallbladder varices, portal biliopathy, and gallbladder bed perfusion abnormalities.

Hepatic "hot-spot" on angio-computed tomography: the role of inferior Sappey's and ensiform veins

Hepatic "hot spots" in anterior paraumbilical hepatic segments of patients suffering from superior vena cava syndrome may be revealed by angio-computed tomography. They may be due to a collateralizing system, the epigastric-paraumbilical venous system (EPVS), which enters the liver as a "third inflow". We report a typical case emphasizing the role of the ensiform and inferior Sappey's veins which constitute typical anatomic components of the EPVS.

Changes of the hepatic subcapsular blood flow in a case of high-grade retroperitoneal liposarcoma: what to expect?

Changes of the hepatic subcapsular blood flow with the early appearance of hypervascularity near the falciform ligament are rare radiologic findings. They present most frequently in cases of superior vena cava (SVC) obstruction and are related to the recruitment of the cavo-mammary-phrenic-hepatic-capsule-portal and the cavo-superficial-umbilical-portal pathways. We present the case of a 52-year-old female patient with an highly aggressive retroperitoneal liposarcoma with SVC obstruction caused by external compression due to a mediastinal metastatic mass. The patient exhibited no symptoms of SVC obstruction due to the collateral cavo-portal pathways.

Use of diffusion-weighted imaging in the noninvasive diagnostic of obstructed biliary ducts

OBJECTIVE

This study sought to evaluate the role of diffusion-weighted imaging (DWI) in differentiation between obstructed and unobstructed bile ducts in patients undergoing magnetic resonance imaging (MRI).

METHODS

Eighty-four patients, 40 males and 44 females (mean age: 56.4 ± 15.1 years), undergoing MRI with DWI (0-50-500-700) were evaluated and divided into two groups: 58 with abnormal laboratory tests (obstructed group) and 26 with normal laboratory values (unobstructed group). Laboratory tests were total bilirubin, alkaline phosphatase, and gamma-glutamyltransferase. Median ADC values were calculated and correlated with laboratory tests and degree of bile-duct dilatation (absent, moderate, or severe). The persistence of signal on DWI (b500 and b700) in the biliary tract was evaluated. Bilirubin values were tested for correlation with bile-duct ADC values and persistence of b700 signal. For statistical analysis, Student t test, chi-square test and Wilcoxon-Mann-Whitney test were used. ADC maps were plotted for three levels of the biliary tree, and a receiver operating characteristic (ROC) curve was calculated.

RESULTS

In the obstructed group, 15 patients had severe dilatation, 24 had moderate dilatation, and 19 had no appreciable dilatation; 38 patients had persistent signal on b700 images. In the unobstructed group, 23 patients had no dilatation and 3 had moderate dilatation; 4 patients had persistent signal on b700 images. Correlation was found between degree of bile-duct dilatation, bilirubin levels, persistence of b700 signal, and ADC map values. The calculated ADC map cutoff value (353 10^-6 mm²/s) was able to differentiate the obstructed and unobstructed groups with 92.3% sensitivity, 81% specificity, and 91.9% accuracy.

CONCLUSIONS

DWI is able to distinguish patients with obstructed versus unobstructed bile ducts, regardless of the degree of dilatation, correlating with clinical and laboratory findings.

Pseudolesion in the right parafissural liver parenchyma on CT: The base is found in embryology and collagen content

Background

Computed tomography (CT) images of livers may show a hypo-attenuated structure alongside the falciform ligament, which can be a focal fatty pseudolesion and can mimic a malignancy. The preferred location is on the right parafissural site, ventral in segment IVa/b. The etiology is not clear, nor is it known how the histology of this location develops. These are evaluated in this study.

Methods

40 adult cadavers with autopsy and / or postmortem CT in a university hospital and a forensic center were included. Liver biopsies were taken at the left side of the falciform ligament as control, and at the right side as the possible precursor of a pseudolesion; these were examined for collagen and fat content. Cadavers with steatotic (>5% fat) or fibrotic (>2% collagen) control samples were excluded.

Results

Significantly more collagen was present in the right parafissural liver parenchyma: median 0.68% (IQR: 0.32–1.17%), compared to the left side 0.48% (IQR: 0.21–0.75%) (p 0.008), with equal fat content and CT attenuation values. The etiophysiology goes back to the demise of the umbilical venes in the early embryonic and neonatal period.

Conclusions

The right parafissural area contains more collagen and an equal amount of fat compared to the control left side. This supports the hypothesis of delayed, ‘third’ inflow: the postnatal change in blood supply from umbilical to portal leaves the downstream parafissural area hypoperfused leading to hypoxia which in turn results in collagen accumulation and the persistence of paraumbilical veins of Sappey.

Spectrum of Pitfalls, Pseudolesions, and Misdiagnoses in Noncirrhotic Liver

OBJECTIVE

The purpose of this article is to illustrate the various pitfalls, mimics, and atypical features that can lead to inaccurate diagnosis of focal lesions in a noncirrhotic liver. The content includes relevant pathogenesis and background as well as specific clues that can be used to reach an accurate diagnosis.

CONCLUSION

When assessing focal hepatic lesions, it is important to avoid pitfalls and misdiagnoses that can alter the management plan. Helpful strategies for avoiding pitfalls include paying close attention to the clinical history of the patient, carefully evaluating all of the available imaging studies, and being aware of the various radiologic mimics.

Focal hypersteatosis: a pseudolesion in patients with liver steatosis

PURPOSE

We aimed to describe ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) findings of focal hypersteatosis (FHS).

METHODS

We retrospectively reviewed our database for patients with hypersteatosis. Over a 5-year period (February 2005 to September 2010) a total of 17 321 patients underwent abdominal CT scan and 28 patients were determined to have FHS. All patients had US, CT, and MRI studies. Size, area, and density measurements were performed on CT images. Fat signal percentage (FSP) was measured on T1-weighted in- and out-of-phase gradient-echo images. FHS was defined based on MRI findings, as an area of greater signal drop on out-of phase images compared with the rest of the fatty liver.

RESULTS

The period prevelance of focal hypersteatosis was measured as 0.16% over the 5-year period. Cancer was the most common diagnosis (22 of 28 patients, 78.5%), with the breast (32.1%) and colorectal (25%) cancers predominating. FHS was seen in segment 4 (n=26, 92.8%), segment 8 (n=1, 3.6%), and segment 3 (n=1, 3.6%). Shape was nodular in 21 patients (75%), while triangular or amorphous in the remaining 7 patients (25%). FHS was hyperechoic and isoechoic in 5 (17.9%) and 23 (82.1%) patients, respectively. FHS was hypodense on CT of all patients relative to fatty liver. On MRI, the FHS was hyperintense on T1-weighted in-phase images in 17 patients (60.7%). Median liver parenchymal FSP was 21.5% (range, 10%-41.4%) and median FSP of hypersteatotic area was 32.5% (range, 19%-45%).

CONCLUSION

Focal hypersteatosis is a pseudolesion that can be observed in patients with liver steatosis. It appears hypodense on CT and mostly isoechoic on US relative to fatty liver. It may mimic metastasis in cancer patients with steatosis, due to nodular shape and atypical location. MRI should be used for correct diagnosis in patients with equivocal findings on CT to avoid biopsy.

Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT

OBJECTIVE

The purpose of this study was to evaluate the imaging characteristics of liver metastases overlooked at contrast-enhanced CT.

MATERIALS AND METHODS

The records of 746 patients with a diagnosis of liver metastases from colorectal, breast, gastric, or lung cancer between November 2010 and September 2017 were reviewed. Images were reviewed when liver metastases were first diagnosed, and images from prior contrast-enhanced CT examinations were checked if available. These lesions were classified into two groups: missed lesions (those missed on the prior images) and detected lesions (those correctly identified and invisible on the prior images or there were no prior images). Tumor size, contrast-to-noise ratio, location, presence of coexisting liver cysts and hepatic steatosis, and indications for examination were compared between the groups. The t test and Fisher exact test were used to analyze the imaging characteristics of previously overlooked lesions.

RESULTS

The final analysis included 137 lesions, of which 68 were classified as missed. In univariate analysis, contrast-to-noise ratio was significantly lower in missed lesions (95% CI, 2.65 ± 0.24 vs 3.90 ± 0.23; p < 0.001). The proportion of subcapsular lesions (odds ratio, 3.44; p < 0.001), hepatic steatosis (odds ratio, 6.35; p = 0.007), and examination indication other than survey of malignant tumors (odds ratio, 9.07; p = 0.02) were significantly higher for missed lesions.

CONCLUSION

Liver metastases without sufficient contrast enhancement, those in patients with hepatic steatosis, those in subcapsular locations, and those found at examinations for indications other than to assess for tumors were significantly more likely to be overlooked.

Multifocal fatty liver disease, insulin resistance and carotid atherosclerosis: exploring the interrelated relationship

Introduction: Multifocal fatty liver infiltrations are not uncommon ultrasonographic finding; they are explained by the presence of aberrant vascular supply independent of the portal circulation or insulin resistance. Aim: To study the significance of this ultrasonographic finding. Methods: A study group (n = 96) with multifocal fatty liver and two control groups: healthy subjects (n = 100) and patients with diffuse fatty liver disease (n = 100) were enrolled. They were tested for fasting blood glucose, lipid profile, transaminases, serum insulin, glycated hemoglobin, Homeostatic Model Assessment of Insulin Resistance, high-sensitivity C-reactive protein and liver stiffness in Fibroscan. Results: Patients with multifocal fatty liver showed a statistically significant higher values of serum transaminases, markers of insulin resistance, high-sensitivity C-reactive protein, and neutrophil lymphocyte ratio (p <0.05). Lipid profile parameters were significantly higher (p <0.05). Mean liver stiffness (9.8 ± 1.2 kPa) and carotid intima media thickness (1.16 ± 0.2 mm) were significantly higher when compared to healthy subjects and patients with diffuse fatty liver disease. Independent predictors of insulin resistance and premature carotid atherosclerosis in patients with multifocal fatty liver disease were: serum gamma-glutamyl transferase (odds ratio 1.69), high-sensitivity C-reactive protein (odds ratio 1.62), uric acid (odds ratio 1.55), very low-density lipoprotein (odds ratio 1.74), total cholesterol/high-density lipoprotein (odds ratio 1.58) and severity of liver stiffness measured by Fibroscan (odds ratio 1.9). Conclusions: Multifocal fatty liver is an aggressive form of nonalcoholic fatty liver disease and should be considered a radiological sign of insulin resistance that needs special attention and management.

Introduction: Multifocal fatty liver infiltrations are not uncommon ultrasonographic finding; they are explained by the presence of aberrant vascular supply independent of the portal circulation or insulin resistance. Aim: To study the significance of this ultrasonographic finding. Methods: A study group (n = 96) with multifocal fatty liver and two control groups: healthy subjects (n = 100) and patients with diffuse fatty liver disease (n = 100) were enrolled. They were tested for fasting blood glucose, lipid profile, transaminases, serum insulin, glycated hemoglobin, Homeostatic Model Assessment of Insulin Resistance, high-sensitivity C-reactive protein and liver stiffness in Fibroscan. Results: Patients with multifocal fatty liver showed a statistically significant higher values of serum transaminases, markers of insulin resistance, high-sensitivity C-reactive protein, and neutrophil lymphocyte ratio (p <0.05). Lipid profile parameters were significantly higher (p <0.05). Mean liver stiffness (9.8 ± 1.2 kPa) and carotid intima media thickness (1.16 ± 0.2 mm) were significantly higher when compared to healthy subjects and patients with diffuse fatty liver disease. Independent predictors of insulin resistance and premature carotid atherosclerosis in patients with multifocal fatty liver disease were: serum gamma-glutamyl transferase (odds ratio 1.69), high-sensitivity C-reactive protein (odds ratio 1.62), uric acid (odds ratio 1.55), very low-density lipoprotein (odds ratio 1.74), total cholesterol/high-density lipoprotein (odds ratio 1.58) and severity of liver stiffness measured by Fibroscan (odds ratio 1.9). Conclusions: Multifocal fatty liver is an aggressive form of nonalcoholic fatty liver disease and should be considered a radiological sign of insulin resistance that needs special attention and management.

Liver vascular anatomy: a refresher

To prevent and decrease procedural complications, it is important to identify variants of hepatic vascular anatomy before interventional radiologic procedures, surgery, and liver transplantation. Knowledge of the vascular variants helps in selecting patients and in exploring alternative management options. Non-invasive detailed demonstration of the hepatic vascular anatomy is possible with advanced multi-detector computed tomography (CT) and magnetic resonance (MR) imaging. The objective of this review is to provide a brief overview of clinically relevant hepatic vascular anatomy and important variants.

Hepatic Hemangioma on SPECT Myocardial Perfusion Imaging

Extracardiac uptake on SPECT MPI, seen with physiologic radiotracer distribution, benign or malignant neoplasm, infection, inflammation, or granulomatous disease, may confound the accuracy of MPI or lead to unsuspected pathology. A 38-year-old woman with end-stage renal disease on hemodialysis had SPECT MPI for renal transplant preoperative risk stratification, showing left anterior descending artery ischemia and an intense extracardiac soft tissue focus adjacent to the diaphragmatic right ventricle concerning for focal infection related to prior coronary or gastric surgeries or tumor. CT revealed focal herniation of liver containing a flash-fill hemangioma into the left hemithorax accounting for this focal uptake.

Malignant Venous Obstruction: Superior Vena Cava Syndrome and Beyond

Venous obstruction in the cancer population can result in substantial morbidity and, in extreme cases, mortality. While venous obstruction can be caused by both benign and malignant etiologies in this population, the management of malignant venous obstruction as a palliative measure can be somewhat nuanced with respect to nonprocedural and procedural management, both with respect to treatment of the underlying malignancy as well as treatment of venous hypertension, which may be associated with venous thrombosis. Symptom severity, primary malignancy, functional status, and prognosis are all fundamental to the patient workup and dictate both the timing and extent of endovascular intervention. The morbidity and mortality associated with malignant obstructions of central venous structures, specifically the superior vena cava and inferior vena cava, can be significantly improved with endovascular management in appropriately selected patients. Thus, the pertinent literature regarding the clinical presentation, workup, and endovascular management of malignant central venous obstruction syndromes, with directed attention to superior vena cava syndrome and inferior vena cava syndrome, will be reviewed in this article.

Prognostic value of incidental hypervascular micronodules detected on cone-beam computed tomography angiography of patients with liver metastasis

PURPOSE

To determine the clinical relevance of incidentally-found hypervascular micronodules (IHM) on cone-beam computed tomography angiography (CBCTA) in patients with liver metastasis undergoing transarterial (chemo)embolization (TACE/TAE).

MATERIAL AND METHODS

This was a HIPAA-compliant institutional review board-approved single-institution retrospective review of 95 non-cirrhotic patients (52 men; mean age, 60 years) who underwent CBCTA prior to (chemo)embolic delivery. IHM were defined by the presence of innumerable subcentimetre hepatic parenchymal hypevascular foci not detected on pre-TACE/TAE contrast-enhanced cross-sectional imaging. Multivariate analysis was performed to compare time to tumour progression (TTP) between patients with and without IHM.

RESULTS

IHM were present in 21 (22%) patients. Patients with IHM had a significantly shorter intrahepatic TTP determined by a higher frequency of developing new liver metastasis (hazard ratio [HR]: 1.99; 95% confidence interval [CI] 1.08-3.67, P= 0.02). Patients with IHM trended towards a shorter TTP of the tumour(s) treated with TACE/TAE (HR: 1.72; 95% CI: 0.98-3.01, P= 0.056). Extrahepatic TTP was not significantly different between the two cohorts (P= 0.27).

CONCLUSION

Patients with IHM on CBCTA have worse prognosis due to a significantly higher risk of developing new hepatic tumours. Further work is needed to elucidate its underlying mechanisms of pathogenesis.

KEY POINTS

• 21% of liver metastasis patients undergoing TACE/TAE have IHM on CBTA. • IHM are associated with a high risk of developing new hepatic tumours. • IHA are also associated with a trend toward poorer response to TACE/TAE.

Liver parenchyma at the site of hypodense parafissural pseudolesion contains increased collagen

PURPOSE

To identify a histological substrate explaining the hypodense pseudolesion in the liver at the right side of the falciform ligament and the correlation with CT radiodensity.

MATERIALS AND METHODS

Tissue specimens were obtained from the right (pseudolesion) and left (control) side of the falciform ligament at the level of the left portal vein, in deceased adults during autopsy. Radiodensity was measured at the same locations at CT. Digital image analysis determined the amount of collagen and fat in histological sections, and the number of portal triads and central veins were counted. Glycogen content was visually assessed by the area percentage of the histological section.

RESULTS

Specimens from 17 patients showed a 39% increase in collagen for the site of the pseudolesion compared to the contralateral side (p = 0.08). No significant differences were found for the amount of fat, glycogen, portal triads, or central veins. In one patient a pseudolesion was visible on CT, and this contained 52% more collagen than the control side.

CONCLUSION

The pseudolesion at the right parafissural side in the liver contains more collagen compared to the control left side, while there is no difference in fat or glycogen content or number of portal and hepatic veins. Collagen may be the cause of the pseudolesion.

Pseudolesion in segment IV A of the liver from vein of Sappey secondary to SVC obstruction

Pseudolesions in the liver are caused by unusual/altered hemodynamics of the liver and can be confused with a true hepatic mass. In superior vena cava (SVC) obstruction. there is recruitment of the cavo-mammary-phrenic-hepatic-capsule-portal pathway. and the venous blood follows the internal mammary vein, the inferior phrenic vein, the hepatic capsule veins, and the intrahepatic portal system. causing a hypervascular pseudolesion in segment IV A of the liver. Recognizing the classic appearances of this hypervascular pseudolesion from the vein of Sappey in a CT study of the abdomen has prognostic implications in directing further evaluation of the chest for SVC obstruction. We present a case of a 54-year-old HIV-positive male smoker in whom identification of the hypervascular pseudolesion from the vein of Sappey on the abdominal CT led to the diagnosis of SVC syndrome.

Hepatic fat quantification using the proton density fat fraction (PDFF): utility of free-drawn-PDFF with a large coverage area

PURPOSE

To evaluate the diagnostic performance of magnetic resonance imaging-estimated proton density fat fraction (MRI-PDFF) using a free-drawn region-of-interest (ROI) measurement of hepatic fat deposition compared to MR spectroscopy (MRS) as the reference standard.

MATERIALS AND METHODS

A total of 156 patients underwent 3T MR imaging with a multi-step adaptive fitting approach, multi-echo volume interpolated breath-hold examination (VIBE) acquisition and single-voxel high-speed T2-corrected multiple-echo (1)H-MR spectroscopy (SVS). Seven ROI measurements were performed in each segment of the fat percentage maps ("segmental-PDFF"). Three ROIs were placed at the same level as the SVS ("VOI-PDFF"). Free-hand-drawn ROIs were placed at three different levels along the entire liver ("free-drawn-PDFF") and separately along the right and left lobes ("free-drawn-PDFF-2").

RESULTS

A strong correlation was found between VOI-PDFF and SVS (r = 0.977). The right lobe had greater fat content than the left lobe (p < 0.001). After image analysis, 54 and 46 patients were classified as having steatosis using SVS and free-drawn-PDFF as a reference standard, respectively. The diagnostic performance of free-drawn-PDFF was significantly different from SVS (p < 0.05).

CONCLUSION

Free-drawn-PDFF provides accurate and generalized information regarding hepatic fat deposition. It is a useful method, particularly if fat deposition is heterogeneous, and should be considered as a new reference standard.

Focal fatty change in the liver that developed after cholecystectomy

Focal fatty change of the segment IV of the liver has been attributed to local systemic venous inflow replacing the portal venous supply, which could develop or be accentuated after gastrectomy. However, focal fatty change due to aberrant pancreaticoduodenal vein that developed after cholecystectomy has never been reported. We report a 30-year-old man with such a rare lesion, which was initially misdiagnosed as a hepatocellular carcinoma, but was confirmed on computed tomography during selective gastroduodenal arteriography. The lesion disappeared 12 mo later without any intervention.

Perfusion and parenchymal changes related to vascular alterations of the liver

Imaging plays a significant role in the diagnosis of vascular abnormalities of the liver and sometimes provides the only clue to the correct diagnosis. With advances of imaging techniques and multiphasic acquisition of liver imaging, various perfusion changes are frequently encountered. Correct imaging diagnosis of significant vascular diseases can prompt appropriate work-up and timely management. Accurate differentiation of clinically insignificant perfusion phenomena from clinically significant findings including neoplastic conditions and in the setting of post-transplantation is essential. This pictorial essay illustrates various perfusion and parenchymal changes associated with portal venous inflow, hepatic venous outflow, and non-portal venous third inflow and describes brief background pathophysiology and differential points.

Prevalence of hepatic pseudolesions around the falciform ligament in a paediatric population

This study investigated the prevalence and features of hepatic pseudolesions around the falciform ligament in 320 children undergoing contrast-enhanced abdominal multidetector computed tomography. Aberrant venous drainage was investigated using thin-section computed tomography images. Pseudolesions around the falciform ligament were detected in 63 patients (20%). The longest diameter was in the craniocaudal direction in 41 (65%) patients (lesions). An inferior vein of Sappey supplying the pseudolesions was seen in 11 patients (17%). Thirteen patients of the 63 patients (21%) with pseudolesions who had a history of extrahepatic malignancy were also examined by ultrasound; in two of the 13 patients the lesions were isoechoic and, in the remainding 11 patients, they were hyperechoic. It was concluded that hepatic pseudolesions around the falciform ligament occur frequently in the paediatric population on CT images. Detection of the longest diameter in the craniocaudal direction and the presence of an inferior vein of Sappey and fatty infiltration should be sufficient to exclude true lesions and make further evaluations unnecessary.

Confident non-invasive diagnosis of pseudolesions of the liver using diffusion-weighted imaging at 3T MRI

PURPOSE

Pseudolesions of the liver including focal steatosis or non-steatosis and THID (transient hepatic intensity differences) are often challenging, especially when imaging patients with underlying malignant disease. We evaluated the efficacy of diffusion-weighted imaging (DWI) in the diagnostic work-up of pseudolesions.

MATERIALS AND METHODS

Forty-eight patients with pseudolesions of the liver were consecutively examined and the images were retrospectively analyzed. MRI was performed on a clinical 3T scanner using T1-GRE in-phase and opposed phase images, T2-TSE-FS, diffusion-weighted sequences (b-value 50, 300, 600), ADC mapping, and dynamic post-contrast T1-VIBE-FS sequences (32 patients received Gd-EB-DTPA and 16 patients received gadolinium chelates). All images were analyzed by two experienced radiologists in consensus. As a standard of reference, we used the T1-w GRE, in-phase and out of phase, and the contrast enhanced series, as well as long-term follow-up.

RESULTS

In the 48 patients, a total of 116 liver lesions were found. Of these, 40 were benign and eleven were malignant focal lesions. Benign lesions included one FNH, 26 simple cysts, and twelve hemangiomas. In addition, 65 pseudolesions (20 focal steatosis, 13 focal non-steatosis, and 32 THIDs) were found. All pseudolesions could be identified either on the T1-GRE in-phase and opposed phase images or on the contrast-enhanced series, or on both. However, none of them were visible on the diffusion-weighted images.

CONCLUSION

Pseudolesions are invisible on DWI (negative predictive value = 1); therefore, DWI can be used as an additional sequence to significantly increase diagnostic confidence in the differentiation between pseudolesions and other focal liver lesions.

Imaging appearance of severe subcapsular hepatic steatosis: mimicking hepatic embolic infarcts

We report a case of severe subcapsular hepatic steatosis in a middle-aged woman with diabetic nephropathy requiring continuous ambulatory peritoneal dialysis (CAPD). The CT appearances of the liver were initially suspected to be due to embolic infarcts. However, an accurate diagnosis was made only after a history of intraperitoneal insulin administration was elicited, and this was confirmed on MRI with chemical shift gradient-echo pulse sequences. Haemodialysis was recommenced, and follow-up imaging 4 years later showed complete resolution of subcapsular hepatic steatosis.

Imaging presentation of venous thrombosis in patients with cancer

OBJECTIVE

The purpose of this article is to review the imaging of venous thrombosis in patients with cancer.

CONCLUSION

Multiple imaging techniques have the capacity to display thrombosis accurately. The optimal choice is dictated by the location and duration of symptoms and by the availability of imaging techniques. Peripheral and superficial thrombi are best managed with ultrasound, whereas central thrombi require CT or MRI. If CT and MRI are contraindicated, flow studies are appropriate. FDG PET/CT appropriately shows venous thrombosis and might play a prominent role in the future.

Anomaly of iliac veins: a rare cause of transient hepatic attenuation difference in a child

We report a case of transient hepatic attenuation difference (THAD) in a child caused by iliac vein anomaly. Iliac vein anomaly as a cause for THAD in a child is extremely rare.

Analysis of focal spared areas in fatty liver using color Doppler imaging and contrast-enhanced microvessel display sonography

OBJECTIVE

The purpose of this study was to investigate whether focal fatty sparing (FFS) formation in the liver relates to aberrant blood flow.

METHODS

Sixty-three FFSs of the liver in 52 patients were examined by color Doppler flow imaging and contrast-enhanced microvessel display sonography. The 63 FFSs included 16 FFSs in the porta hepatis, 14 FFSs around the gallbladder fossa, and 33 other FFSs. The control group included patients with a diagnosis of fatty liver but no FFSs or focal lesions near the porta hepatis.

RESULTS

Fourteen of 16 FFSs in the porta hepatis showed venous blood toward those areas that were differentiated from the portal and hepatic veins. Focal fatty sparings in the hilus hepatis correlated with aberrant veins, having a statistical significance compared with the control group (P < .0001). Seven of 14 FFSs around the gallbladder fossa contained blood vessels, 5 of them veins and the remaining 2 arteries. Two FFSs were located around hemangiomas. Three FFSs were located around maldeveloped vessels.

CONCLUSIONS

The blood supply to an FFS in the porta hepatis may be correlated with aberrant veins. Focal fatty sparings around the gallbladder fossa may be associated with aberrant blood flow.

Spectrum of hepatic surface enhancement on contrast-enhanced CT in various abdominal conditions

Hepatic surface enhancement on CT can represent particular clinical significance in various abdominal conditions, at times being the only abnormality found. Detecting hepatic surface enhancement, together with the other ancillary diagnostic techniques as well, may lead to grasp of the underlying condition and to early or timely diagnosis and treatment of abdominal disorders. This manuscript describes the spectrum of hepatic surface enhancement on CT, and the importance of focusing on the hepatic surface during interpretation is emphasized.