Imaging Features in the Liver after Stereotactic Body Radiation Therapy

LI-RADS radiation-based treatment response algorithm for HCC: what to know and how to use it

Locoregional treatments (LRT) continue to advance for hepatocellular carcinoma (HCC). Selective internal radiation therapy (SIRT) or transarterial radioembolization (TARE) with radioactive 90 Yttrium (Y90) microspheres is currently widely accepted, and external beam and stereotactic body radiation (EBRT/SBRT) are increasingly used as LRT1-5. Assessment of treatment response after these radiation-based therapies can be challenging, given that the adjacent liver also undergoes treatment related changes, inflammatory changes occur, and there is a variable time for response to develop. In 2017, the liver imaging reporting and data system (LI-RADS) workgroup initially developed a single algorithm for the imaging assessment of treatment response encompassing all types of locoregional therapies, the LI-RADS treatment response (LR-TR) algorithm. Recognizing that response and imaging patterns differ between radiation and non-radiation based therapies, the LR-TR working group recently updated the algorithm to reflect the unique characteristics of tumor response for therapies involving radiation. This article aims to elucidate the changes in the new version of the LI-RADS TR, with a guide for algorithm utilization and illustration of expected and unexpected findings post liver directed therapies for HCC.

Current State of Evidence for Use of MRI in LI-RADS

The American College of Radiology Liver Imaging Reporting and Data System (LI-RADS) is the preeminent framework for classification and risk stratification of liver observations on imaging in patients at high risk for hepatocellular carcinoma. In this review, the pathogenesis of hepatocellular carcinoma and the use of MRI in LI-RADS is discussed, including specifically the LI-RADS diagnostic algorithm, its components, and its reproducibility with reference to the latest supporting evidence. The LI-RADS treatment response algorithms are reviewed, including the more recent radiation treatment response algorithm. The application of artificial intelligence, points of controversy, LI-RADS relative to other liver imaging systems, and possible future directions are explored. After reading this article, the reader will have an understanding of the foundation and application of LI-RADS as well as possible future directions.

Hypointense Findings on Hepatobiliary Phase MR Images

Hepatobiliary (HB) contrast agents are increasingly valuable diagnostic tools in MRI, offering a wider range of applications as their clinical use expands. Normal hepatocytes take up HB contrast agents, which are subsequently excreted in bile. This property creates a distinct HB phase providing valuable insights into liver function and biliary anatomy. HB contrast agents can assist in diagnosing a broad spectrum of HB diseases ranging from diffuse liver disease to focal hepatic lesions and can delineate anatomic details of the biliary tree. Understanding the pharmacodynamics of HB contrast agents is paramount to their appropriate clinical application and troubleshooting. HB phase hypointensity can arise from various diffuse and focal abnormalities that may or may not be associated with biliary excretion. Hypointensity during the HB phase can be broadly grouped into diffuse hypointensity, regional hypointensity, and focal lesions for better evaluation of the underlying cause. Abnormalities may arise from hepatic parenchymal, biliary, or vascular causes, or a combination thereof in each of the broad groups. Recognition of a suboptimal hypointense HB phase is important in the evaluation of focal lesions in patients with cirrhosis of the liver and particularly in those with hepatocellular carcinoma. Furthermore, hypointensity can also suggest the aggressiveness of malignancies such as hepatocellular carcinoma or colorectal metastases, which may affect the prognosis. It is essential to consider all imaging findings relative to the clinical context and the complete set of the MRI sequences performed for diagnosis of liver abnormalities. This comprehensive approach minimizes the risk of misinterpretation or pitfalls. The authors aim to equip radiologists with key insights for accurately understanding hypointensity in the HB phase, ultimately leading to more accurate diagnoses. ©RSNA, 2025 Supplemental material is available for this article.

Exploring the Evolving Landscape of Stereotactic Body Radiation Therapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) carries significant morbidity and mortality. Management of the HCC requires a multidisciplinary approach. Surgical resection and liver transplantation are the gold standard options for the appropriate settings. Stereotactic body radiation therapy (SBRT) has emerged as a promising treatment modality in managing HCC; its use is more studied and well-established in advanced HCC (aHCC). Current clinical guidelines universally endorse SBRT as a viable alternative to radiofrequency ablation (RFA), transarterial chemoembolisation (TACE), and transarterial radioembolisation (TARE), a recommendation substantiated by literature demonstrating comparable efficacy among these modalities. In early-stage HCC, SBRT primarily manages unresectable tumours unsuitable for ablative procedures such as microwave ablation and RFA. SBRT has been incorporated as a modality to downstage tumours or as a bridge to transplant. In the case of intermediate or advanced HCC, SBRT offers excellent results either as a single modality or adjunct to other locoregional modalities such as TACE/TARE. Recent data from late-stage HCC patients illustrate the effectiveness of SBRT in achieving local tumour control while minimising damage to surrounding healthy liver tissue. It has promising local control of approximately 80-90% in managing HCC. Additional prospective data comparing the efficacy of SBRT with the first-line recommended therapies such as RFA, TACE, and surgery are essential. The standard of care for patients with advanced/metastatic disease is systemic therapy (immunotherapy/tyrosine kinase inhibitors). SBRT, in combination with immune-checkpoint inhibitors, has an immune-modulatory effect that results in a synergistic effect. Recent findings indicate that the combination of immunotherapy and SBRT in HCC is well-tolerated and exhibits synergistic effects. Further exploration of diverse immunotherapy and radiotherapy strategies is essential to identify the appropriate time for combination treatments and to optimise dose and fraction regimens. Prospective, randomised studies are imperative to establish SBRT as the primary treatment for HCC.

Impact of right-sided breast cancer adjuvant radiotherapy on the liver

BACKGROUND

In patients with right-sided breast cancer the liver can be partially irradiated during adjuvant radiotherapy (RT). We aimed to determine breast cancer RT effects on liver using with magnetic resonance elastography (MRE) and biological results.

PATIENTS AND METHODS

This retrospective study enrolled 34 patients diagnosed with right-sided breast cancer who underwent adjuvant RT. Liver segment assessments were conducted using MRE for all participants. Additionally, a complete blood count and liver enzyme analysis were performed for each patient. All measurements were taken both prior to the initiation and upon completion of RT.

RESULTS

A statistically significant difference was found in ALT (p = 0.015), ALP (p = 0.026), total protein (p = 0.037), and albumin (p = 0.004) levels before and after RT. The highest mean liver stiffness (kPa) value was recorded in segment 8, while the lowest was observed in segment 6. A weak but statistically significant positive correlation was found between segment 5 stiffness and liver volume (p = 0.039). Additionally, a statistically significant positive correlation was detected between ALP levels and the stiffness values in segment 4A (p = 0.020) and segment 6 (p = 0.003). Conversely, a weak negative correlation was observed between the stiffness values in segment 8 and post-RT total protein levels (p = 0.031).

CONCLUSIONS

MRE can help us identify the level of fibrotic stiffness in the liver segments within the RT area without establishing clinical symptoms. MRE can support the clinician in evaluating the liver functions of right breast cancer patients who underwent RT. We assume these results will facilitate new studies with a large number of patients on MRE imaging at certain intervals in the follow-up of patients with right breast cancer who received RT before the development of radiation-induced liver disease (RILD).

Durable Response to Combined Nivolumab, Lenvatinib, and Radiation Therapy Against Oligometastatic Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and is associated with major risk factors such as hepatitis B virus (HBV), hepatitis C virus (HCV), alcoholic fatty liver disease, and metabolic dysfunction-associated steatotic liver diseases. Despite the recent progress in systemic treatment regimens involving immunotherapies and targeted therapeutics, advanced HCC remains difficult to control. Moreover, with several treatment modalities currently available for HCC such as radiation therapy, transarterial chemoembolization (TACE), checkpoint immunotherapies, and multi-tyrosine kinase inhibitors, it is unclear what combination yields the greatest treatment efficacy and durability. Here, we present the case of a male patient in his 60s with HCV-associated cirrhosis diagnosed with HCC with a metastatic lesion to the T9 spine. Treatment with nivolumab and subsequently lenvatinib in addition was complicated by adverse effects including hand rash and kidney injury. Systemic therapy was stopped, and consolidative stereotactic body radiation therapy (SBRT) was delivered to the sites of the disease. The combination proved to be highly durable without any evidence of progression for over three years despite having stopped all therapy. All toxicities have resolved since, and the patient remains very active. This case demonstrates the feasibility of combining therapeutic modalities to achieve exceptional disease control in the setting of oligometastatic disease.

Hepatic Sinusoidal Disorders

Hepatic sinusoids are highly specialized microcirculatory conduits within the hepatic lobules that facilitate liver functions. The sinusoids can be affected by various disorders, including sinusoidal dilatation, sinusoidal obstruction syndrome (SOS), sinusoidal cellular infiltration, perisinusoidal infiltration, and endothelial neoplasms, such as hemangioendothelioma and angiosarcoma. While these disorders, particularly SOS and neoplasms, can be life threatening, their clinical manifestation is often nonspecific. Patients may present with right upper quadrant pain, jaundice, hepatomegaly, ascites, splenomegaly, and unexplained weight gain, although the exact manifestation depends on the cause, severity, and duration of the disease. Ultimately, invasive tests may be necessary to establish the diagnosis. A comprehensive understanding of imaging manifestations of various sinusoidal disorders contributes to early diagnosis and can help radiologists detect subclinical disease. Additionally, specific imaging features may assist in identifying the cause of the disorder, leading to a more focused and quicker workup. For example, a mosaic pattern of enhancement of the liver parenchyma is suggestive of sinusoidal dilatation; peripheral and patchy reticular hypointensity of the liver parenchyma on hepatobiliary MR images is characteristic of SOS; and associated diffuse multiple hyperintensities on diffusion-weighted images may be specific for malignant sinusoidal cellular infiltration. The authors provide an overview of the pathogenesis, clinical features, and imaging appearances of various hepatic sinusoidal disorders, with a special emphasis on SOS. ©RSNA, 2024 Supplemental material is available for this article.

Radiation-induced liver disease mimicking liver metastasis after low-dose hepatic irradiation during radiotherapy for gastric mucosa-assisted lymphoid tissue lymphoma: A case report

RATIONALE

Radiation-induced liver disease (RILD) is an established complication of hepatic irradiation that is typically reported in patients receiving high-dose radiotherapy for hepatocellular carcinoma or liver metastases. However, RILD can also occur after unintentional low-dose liver exposure during radiotherapy for other gastrointestinal malignancies when careful precautions are not taken.

PATIENT CONCERNS

We report the case of a 44-year-old woman with gastric mucosa-associated lymphoid tissue lymphoma who underwent salvage radiotherapy administered to the entire stomach. One month after completing this radiotherapy, computed tomography and magnetic resonance imaging of the patient's abdomen revealed a 4 cm lesion in the left lateral liver segment, suggestive of metastasis.

DIAGNOSES

An ultrasound-guided biopsy was performed, and the histopathological findings were consistent with those of RILD.

INTERVENTIONS

Conservative management was pursued with close monitoring of liver function tests.

OUTCOMES

The patient's imaging findings and liver enzyme levels normalized approximately 3 months after the initial diagnosis.

LESSONS

This case highlights the importance of considering RILD in the differential diagnosis of new hepatic lesions detected after radiotherapy, even in patients with low-dose liver exposure within generally acceptable limits. Careful correlation with the radiotherapy plan is crucial to avoid misdiagnosing RILD as metastatic disease and to guide appropriate management.

Imaging Considerations before and after Liver-Directed Locoregional Treatments for Metastatic Colorectal Cancer

Colorectal cancer is a leading cause of cancer-related death. Liver metastases will develop in over one-third of patients with colorectal cancer and are a major cause of morbidity and mortality. Even though surgical resection has been considered the mainstay of treatment, only approximately 20% of the patients are surgical candidates. Liver-directed locoregional therapies such as thermal ablation, Yttrium-90 transarterial radioembolization, and stereotactic body radiation therapy are pivotal in managing colorectal liver metastatic disease. Comprehensive pre- and post-intervention imaging, encompassing both anatomic and metabolic assessments, is invaluable for precise treatment planning, staging, treatment response assessment, and the prompt identification of local or distant tumor progression. This review outlines the value of imaging for colorectal liver metastatic disease and offers insights into imaging follow-up after locoregional liver-directed therapy.

Liver parenchymal changes detected by MR elastography and diffusion-weighted imaging after stereotactic body radiotherapy for hepatocellular carcinoma

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a local treatment option for hepatocellular carcinoma (HCC). SBRT-induced focal reactions on the liver parenchyma have not been thoroughly evaluated using quantitative magnetic resonance imaging (MRI).

PURPOSE

To quantitatively evaluate liver parenchymal changes caused by SBRT for HCC using magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI).

METHOD

We retrospectively evaluated 22 adult patients who received SBRT for HCC and 27 who received locoregional therapy other than SBRT (controls). Liver stiffness by MRE and apparent diffusion coefficient (ADC) values by DWI of the liver parenchyma were measured before and after SBRT. Regions of interest (ROIs) were drawn on the two areas of radiation dose distribution levels, > 30 Gy and ≤ 30 Gy; a ROI was drawn in the control group. The two indices were compared before and after SBRT using a Wilcoxon matched-pairs signed-rank test.

RESULTS

Liver stiffness and ADC values were significantly increased after SBRT in the dose areas of > 30 Gy compared with those before SBRT (4.05 vs 4.85 kPa; p < 0.05 in liver stiffness, and 1.10 vs 1.40 ×10-3 s/mm2; p < 0.05 in ADC values). In the dose area of ≦ 30 Gy, liver stiffness showed a significant increase in one reader (p = 0.033) but not in another reader (p = 0.085); ADC value showed no significant difference before and after SBRT as per both readers (p > 0.05). The control group demonstrated no significant differences before and after treatment (p > 0.05).

CONCLUSION

MRE and DWI can be used to detect SBRT-induced liver parenchymal changes.

Cancer Therapy-related Hepatic Injury in Children: Imaging Review from the Pediatric LI-RADS Working Group

The liver is the primary organ for the metabolism of many chemotherapeutic agents. Treatment-induced liver injury is common in children undergoing cancer therapy. Hepatic injury occurs due to various mechanisms, including biochemical cytotoxicity, hepatic vascular injury, radiation-induced cytotoxicity, and direct hepatic injury through minimally invasive and invasive surgical treatments. Treatment-induced liver injury can be seen contemporaneous with therapy and months to years after therapy is complete. Patients can develop a combination of hepatic injuries manifesting during and after treatment. Acute toxic effects of cancer therapy in children include hepatitis, steatosis, steatohepatitis, cholestasis, hemosiderosis, and vascular injury. Longer-term effects of cancer therapy include hepatic fibrosis, chronic liver failure, and development of focal liver lesions. Quantitative imaging techniques can provide useful metrics for disease diagnosis and monitoring, especially in treatment-related diffuse liver injury such as hepatic steatosis and steatohepatitis, hepatic iron deposition, and hepatic fibrosis. Focal liver lesions, including those developing as a result of treatment-related vascular injury such as focal nodular hyperplasia-like lesions and hepatic perfusion anomalies, as well as hepatic infections occurring as a consequence of immune suppression, can be anxiety provoking and confused with recurrent malignancy or hepatic metastases, although there often are imaging features that help elucidate the correct diagnosis. Radiologic evaluation, in conjunction with clinical and biochemical screening, is integral to diagnosing and monitoring hepatic complications of cancer therapy in pediatric patients during therapy and after therapy completion for long-term surveillance. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material See the invited commentary by Ferraciolli and Gee in this issue.

Thermal ablation compared to stereotactic body radiation therapy for hepatocellular carcinoma: A multicenter retrospective comparative study

BACKGROUND AIMS

Early-stage HCC can be treated with thermal ablation or stereotactic body radiation therapy (SBRT). We retrospectively compared local progression, mortality, and toxicity among patients with HCC treated with ablation or SBRT in a multicenter, US cohort.

APPROACH RESULTS

We included adult patients with treatment-naïve HCC lesions without vascular invasion treated with thermal ablation or SBRT per individual physician or institutional preference from January 2012 to December 2018. Outcomes included local progression after a 3-month landmark period assessed at the lesion level and overall survival at the patient level. Inverse probability of treatment weighting was used to account for imbalances in treatment groups. The Cox proportional hazard modeling was used to compare progression and overall survival, and logistic regression was used for toxicity. There were 642 patients with 786 lesions (median size: 2.1 cm) treated with ablation or SBRT. In adjusted analyses, SBRT was associated with a reduced risk of local progression compared to ablation (aHR 0.30, 95% CI: 0.15-0.60). However, SBRT-treated patients had an increased risk of liver dysfunction at 3 months (absolute difference 5.5%, aOR 2.31, 95% CI: 1.13-4.73) and death (aHR 2.04, 95% CI: 1.44-2.88, p < 0.0001).

CONCLUSIONS

In this multicenter study of patients with HCC, SBRT was associated with a lower risk of local progression compared to thermal ablation but higher all-cause mortality. Survival differences may be attributable to residual confounding, patient selection, or downstream treatments. These retrospective real-world data help guide treatment decisions while demonstrating the need for a prospective clinical trial.

Unique Morphologic Findings in the Liver After Stereotactic Radiation for Cholangiocarcinoma

Newer radiotherapy techniques, such as stereotactic body radiation, have been increasingly used as part of the treatment of cholangiocarcinomas, particularly as a bridge to liver transplantation. Although conformal, these high-dose therapies result in tissue injury in the peritumoral liver tissue. This retrospective study characterized the morphologic changes in the liver after stereotactic body radiation in a series of liver explant specimens with perihilar cholangiocarcinoma. The morphologic changes in the irradiated zone were compared against the nonirradiated background liver parenchyma to control for chemotherapy-related changes. Of the 21 cases studied, 16 patients (76.2%) had underlying primary sclerosing cholangitis, and 13 patients (61.9%) had advanced liver fibrosis. The average duration between completion of radiotherapy and liver transplantation was 33.4 weeks (range: 6.29 to 67.7). Twelve patients (57.1%) had no residual tumor in the liver. The most frequent histologic changes in the peritumoral irradiated liver tissue were sinusoidal congestion (100%), sinusoidal edematous stroma (100%), and hepatocellular atrophy (100%), followed by partial/complete occlusion of central veins (76.2%), sinusoidal cellular infiltrates (76.2%), and hepatocyte dropout (66.7%). The findings in the radiated areas were more extensive than in the background liver ( P <0.01). Sinusoidal edematous stroma was striking and dominated the histologic findings in some cases. Over time, there was less sinusoidal congestion but more hepatocyte dropout (r s =-0.54, P =0.012 and r s =0.64, P =0.002, respectively). Uncommon findings, such as foam cell arteriopathy in the liver hilum, were also observed. In summary, postradiation liver specimens have distinctive morphologic findings.

Role of Functional MRI in Liver SBRT: Current Use and Future Directions

Stereotactic body radiation therapy (SBRT) is an emerging treatment for liver cancers whereby large doses of radiation can be delivered precisely to target lesions in 3-5 fractions. The target dose is limited by the dose that can be safely delivered to the non-tumour liver, which depends on the baseline liver functional reserve. Current liver SBRT guidelines assume uniform liver function in the non-tumour liver. However, the assumption of uniform liver function is false in liver disease due to the presence of cirrhosis, damage due to previous chemo- or ablative therapies or irradiation, and fatty liver disease. Anatomical information from magnetic resonance imaging (MRI) is increasingly being used for SBRT planning. While its current use is limited to the identification of target location and size, functional MRI techniques also offer the ability to quantify and spatially map liver tissue microstructure and function. This review summarises and discusses the advantages offered by functional MRI methods for SBRT treatment planning and the potential for adaptive SBRT workflows.