Transient Hepatic Parenchymal Enhancement detected at dynamic imaging: a short instruction manual for the clinician

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.

Multislice Computed Tomographic Manifestation of Transient Hepatic Attenuation Difference in the Left Lobe of the Liver: A Retrospective Study

INTRODUCTION

Transient hepatic attenuation differences (THAD) are areas of high parenchymal enhancement observed during the hepatic arterial phase on computed tomography (CT). THAD in the left lobe of the liver can lead to surgical complications.

METHODS

A retrospective study was conducted on patients who underwent multislice computed tomography (MSCT) examination of the upper abdomen to understand the morphology, distribution, and causes of THAD and their correlation with hepatic artery variation.

RESULTS

Among 179 cases, 65 and 114 belonged to diseased and normal groups, respectively. THAD as observed in MSCT demonstrated various shapes: lobe/segment (127 cases; 70.9%), irregular sheet (31; 17.3%), strip shape (9; 5.02%), arc/semicircle (7; 3.9%), and segment + flaky (5; 2.79%). THAD were found to be caused by liver tumor (32.3%), hepatic inflammatory lesions (6.15%), biliary tract diseases (13.8%), perihepatic disease compression (9.23%), portal vein obstructive disease (1.53%), and lesion in left hepatic lobe with hepatic artery variation (29.2%). THAD exhibited variation in distribution in the left lobe of the liver. Among 114 cases, THAD in 18 (15.7%) cases were observed in the S2 segment, six (5.26%) in the S3 segment, and 90 (78.9%) in multiple segments of the liver, that is, 50 cases in S2 and S3 segments and 40 cases in S2, S3, and S4 segments. The hepatic artery of 179 cases was of various types based on Hiatt classification: 57 cases of Hiatt I (31%), 65 cases of Hiatt II (37%), 11 cases of Hiatt III (6%), 17 cases of Hiatt IV (10%), 7 cases of Hiatt V (4%), 12 cases of large left hepatic artery (7%), 6 cases of right hepatic artery originating from the celiac trunk (3%), and 4 cases (2%) of superior mesenteric artery originating from the celiac trunk.

CONCLUSION

THAD can occur as a result of specific pathological causes and hence should be considered as a diagnostic sign in liver pathologies.

Portal Vein Embolization: Radiological Findings Predicting Future Liver Remnant Hypertrophy

OBJECTIVE. The purpose of this article is to evaluate the radiologic findings predicting the future liver remnant hypertrophy ratio after portal vein embolization of the right branch. MATERIALS AND METHODS. The associations between the radiologic findings and the future liver remnant hypertrophy ratio for 79 patients who underwent portal vein embolization of the right branch between July 2007 and April 2017 were retrospectively analyzed. Multiple linear regression was performed to adjust for potential confounders, and the volume ratio of the right lobe anterior segment, number of proximal small branches from the right anterior and posterior portal veins, transient hepatic parenchymal enhancement, portal vein invasion, and variants of main portal vein anatomy were evaluated. The potential confounders were age, ratio of future liver remnant hypertrophy to total liver volume, indocyanine green clearance rate, maximum serum total bilirubin before portal vein embolization, and history of chemotherapy. RESULTS. Statistically significant associations were found between the future liver remnant hypertrophy ratio and the number of proximal small branches from the right anterior and posterior portal veins (p < 0.001), transient hepatic parenchymal enhancement (p < 0.001), portal vein invasion (p = 0.017), and variants of main portal vein anatomy (p = 0.048). The mean future liver remnant hypertrophy rate was 51.0% (n = 16) in patients without the radiologic findings showing statistically significant differences, and 25.8% (n = 63) in patients with at least one significant finding. CONCLUSION. When added to previously reported factors, the radiologic findings identified can help determine the indications for portal vein embolization and novel strategies for major hepatectomy.

Liver Masses: What Physicians Need to Know About Ordering and Interpreting Liver Imaging

PURPOSE OF REVIEW

This paper reviews diagnostic imaging techniques used to characterize liver masses and the imaging characteristics of the most common liver masses.

RECENT FINDINGS

The role of recently adopted ultrasound and magnetic resonance imaging contrast agents will be emphasized. Contrast-enhanced ultrasound is an inexpensive exam which can confirm benignity of certain liver masses without ionizing radiation. Magnetic resonance imaging using hepatocyte-specific gadolinium-based contrast agents can help confirm or narrow the differential diagnosis of liver masses.

The Impact of Transient Hepatic Attenuation Differences in the Diagnosis of Pseudoaneurysm and Arteriovenous Fistula on Follow-Up CT Scans after Blunt Liver Trauma

A feared complication to liver trauma is delayed vascular complication, such as pseudoaneurysm and arteriovenous fistula (PS/AF) seen as focal enhancement on contrast-enhanced computed tomography (CT) in the arterial phase. A hyperdense area termed transient hepatic attenuation difference (THAD) representing altered hepatic blood flow can be seen in the arterial phase near the liver lesion. The objective of this study was to describe THAD and PS/AF on follow-up CT after blunt liver trauma, and to evaluate if THAD influenced the evaluation of PS/AF. Three radiology residents retrospectively evaluated scans of 78 patients. The gold standard for PS/AF was an evaluation by an experienced senior radiologist, while THAD was a consensus between the residents. PS/AF was present in 14% and THAD in 54%. THAD was located in the periphery of the lesion with hazy borders and mean HU levels of 100, while PS/AF was located within the lesion with focal enhancement and mean HU levels of 170 (p < 0.05). In evaluation of PS/AF, the likelihood of agreement between the observers and the gold standard was 89% when THAD was present, and 98% when THAD was absent (p = 0.04). THAD is common and can hamper the evaluation of PS/AF.