Radiation-induced liver injury mimicking liver metastases on FDG-PET-CT after chemoradiotherapy for esophageal cancer: A retrospective study and literature review

False Liver Metastasis by Positron Emission Tomography/Computed Tomography Scan after Chemoradiotherapy for Esophageal Cancer-Potential Overstaged Pitfalls of Treatment

In patients with esophageal cancer undergoing neoadjuvant chemoradiotherapy (nCRT), subsequent restaging with F-18-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) can reveal the presence of interval metastases, such as liver metastases, in approximately 10% of cases. Nevertheless, it is not uncommon in clinical practice to observe focal FDG uptake in the liver that is not associated with liver metastases but rather with radiation-induced liver injury (RILI), which can result in the overstaging of the disease. Liver radiation damage is also a concern during distal esophageal cancer radiotherapy due to its proximity to the left liver lobe, typically included in the radiation field. Post-CRT, if FDG activity appears in the left or caudate liver lobes, a thorough investigation is needed to confirm or rule out distant metastases. The increased FDG uptake in liver lobes post-CRT often presents a diagnostic dilemma. Distinguishing between radiation-induced liver disease and metastasis is vital for appropriate patient management, necessitating a combination of imaging techniques and an understanding of the factors influencing the radiation response. Diagnosis involves identifying new foci of hepatic FDG avidity on PET/CT scans. Geographic regions of hypoattenuation on CT and well-demarcated regions with specific enhancement patterns on contrast-enhanced CT scans and MRI are characteristic of radiation-induced liver disease (RILD). Lack of mass effect on all three modalities (CT, MRI, PET) indicates RILD. Resolution of abnormalities on subsequent examinations also helps in diagnosing RILD. Moreover, it can also help to rule out occult metastases, thereby excluding those patients from further surgery who will not benefit from esophagectomy with curative intent.

Increased 18F-FAPI Uptake in Radiation-Induced Liver Injury

ABSTRACT

A 51-year-old woman with breast cancer underwent a complete surgical resection and chemoradiotherapy approximately 3 months ago. Follow-up abdominal ultrasound detected a new lesion with decreased echogenicity in the hepatic segment IV/VIII. 18F-FDG PET/CT showed the hepatic lesion without abnormal uptake. The patient was subsequently enrolled in a clinical trial of 18F-FAPI PET/CT to assess the hepatic lesion. An intense 18F-FAPI activity was identified in the hepatic lesion. Finally, pathological analysis combined with imaging follow-up confirmed the diagnosis of radiation-induced liver injury.

Radiation-induced liver disease: beyond DNA damage

Radiation-induced liver disease (RILD), also known as radiation hepatitis, is a serious side effect of radiotherapy (RT) for hepatocellular carcinoma. The therapeutic dose of RT can damage normal liver tissue, and the toxicity that accumulates around the irradiated liver tissue is related to numerous physiological and pathological processes. RILD may restrict treatment use or eventually deteriorate into liver fibrosis. However, the research on the mechanism of radiation-induced liver injury has seen little progress compared with that on radiation injury in other tissues, and no targeted clinical pharmacological treatment for RILD exists. The DNA damage response caused by ionizing radiation plays an important role in the pathogenesis and development of RILD. Therefore, in this review, we systematically summarize the molecular and cellular mechanisms involved in RILD. Such an analysis is essential for preventing the occurrence and development of RILD and further exploring the potential treatment of this disease.

Liver Injury in Patients With Distal Esophageal Carcinoma After Precision Radiation Therapy: Systematic Review of FDG-PET/CT Patterns

OBJECTIVE

To determine the incidence and various patterns of radiation-induced liver injury (RILI) and its temporal evolution on fluorodeoxiglucose-positron emission tomography/computed tomography (FDG-PET/CT) after neoadjuvant chemoradiation using precision radiation in patients with esophageal carcinoma.

MATERIAL AND METHODS

We evaluated 639 patients with locally advanced esophageal carcinoma who had serial FDG-PET/CTs after neoadjuvant chemoradiation. Two readers reviewed the imaging studies in consensus and recorded the cases where new foci of increased FDG uptake were identified within the radiated liver parenchyma. RILI was confirmed by follow-up imaging or percutaneous biopsy.

RESULTS

FDG-avid RILI developed in 39/639 (6%) of patients. The caudate and left hepatic lobe were involved in all cases. There were various patterns of increased FDG uptake: 38% of patients had a single focus of increased FDG uptake and 62% had 2 regions of increased FDG uptake, which were focal nodular or diffuse or a combination of focal nodular and diffuse FDG uptake. On CT, 72% of patients had a poorly-marginated region of low attenuation and 28% had a well-defined region of low attenuation with sharp, well-defined linear borders in the location of the radiation, as confirmed by the treatment plan.

CONCLUSION

The caudate and left hepatic lobes were involved in all cases of RILI. The various imaging patterns of RILI on FDG-PET/CT include 1 or 2 regions of increased FDG uptake with a nodular, diffuse, or combined appearance. Awareness of this potential complication of radiation therapy and knowledge of the imaging manifestations of RILI is important to avoid misinterpretation as a metastasis.

Response Evaluation Following Radiation Therapy With 18F-FDG PET/CT: Common Variants of Radiation-Induced Changes and Potential Pitfalls

Radiation therapy (RT) is one of the cornerstones in cancer treatment and approximately half of all patients will receive some form of RT during the course of their cancer management. Response evaluation after RT and follow-up imaging with ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) can be complicated by RT-induced acute, chronic or consequential effects. There is a general consensus that ¹⁸F-FDG PET/CT for response evaluation should be delayed for 12 weeks after completing RT to minimize the risk of false-positive findings. Radiation-induced late side effects in normal tissue can take years to develop and eventually cause symptoms that on imaging can potentially mimic recurrent disease. Imaging findings in radiation induced injuries depend on the normal tissue included in the irradiated volume and the radiation therapy regime including the total dose delivered, dose per fraction and treatment schedule. The intent for radiation therapy should be taken in consideration when evaluating the response on imaging, that is palliative vs curative or neoadjuvant vs adjuvant RT. Imaging findings can further be distorted by altered anatomy and sequelae following surgery within the radiation field. An awareness of common PET/CT-induced changes/injuries is essential when interpreting ¹⁸F-FDG PET/CT as well as obtaining a complete medical history, as patients are occasionally scanned for an unrelated cause to previously RT treated malignancy. In addition, secondary malignancies due to carcinogenic effects of radiation exposure in long-term cancer survivors should not be overlooked. ¹⁸F-FDG PET/CT can be very useful in response evaluation and follow-up in patients treated with RT, however, variants and pitfalls are common and it is important to remember that radiation-induced injury is often a diagnosis of exclusion.

PET-CT in Clinical Adult Oncology: III. Gastrointestinal Malignancies

Simple Summary

Positron emission tomography (PET), typically combined with computed tomography (CT), has become a critical advanced imaging technique in oncology. With PET-CT, a radioactive molecule (radiotracer) is injected in the bloodstream and localizes to sites of tumor because of specific cellular features of the tumor that accumulate the targeting radiotracer. The CT scan, performed at the same time, provides information to facilitate the characterization of radioactivity from deep or dense structures, and to provide detailed anatomic information. PET-CT has a variety of applications in oncology, including staging, therapeutic response assessment, restaging and surveillance. This series of six review articles provides an overview of the value, applications, and imaging interpretive strategies of PET-CT in the more common adult malignancies. The third report in this series provides a review of PET-CT imaging in gastrointestinal malignancies.

Abstract

PET-CT is an advanced imaging modality with many oncologic applications, including staging, assessment of response to therapy, restaging and longitudinal surveillance for recurrence. The goal of this series of six review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for specific oncologic indications, and the potential pitfalls and nuances that characterize these applications. In the third of these review articles, key tumor-specific clinical information and representative PET-CT images are provided to outline the role that PET-CT plays in the management of patients with gastrointestinal malignancies. The focus is on the use of ¹⁸F fluorodeoxyglucose (FDG), rather than on research radiopharmaceuticals under development. Many different types of gastrointestinal tumors exist, both pediatric and adult. A discussion of the role of FDG PET-CT for all of these is beyond the scope of this review. Rather, this article focuses on the most common adult gastrointestinal malignancies that may be encountered in clinical practice. The information provided here will provide information outlining the appropriate role of PET-CT in the clinical management of patients with gastrointestinal malignancies for healthcare professionals caring for adult cancer patients. It also addresses the nuances and provides interpretive guidance related to PET-CT for imaging providers, including radiologists, nuclear medicine physicians and their trainees.

Radiation Induced Liver Injury: Collateral Damage Radiologically Simulating Interval Metastasis in Carcinoma Esophagus; a Diagnostic Dilemma Resolved Through Liver Biopsy

F-18-fluorodeoxyglucose positron emission tomography (18-FDG PET/CT) is increasingly being used in patients with cancer, both for baseline staging and for evaluation of treatment response. However, in patients with incidental irradiation of the liver during radiotherapy, particularly for lower gastrointestinal tract cancers, increased focal F-18-fluorodeoxyglucose positron emission tomography avidity may be the result of collateral radiation induced liver damage rather than metastases. Awareness of this pathologic entity and correlation with with other imaging, clinical and laboratory findings including liver biopsy is vital to avoid misinterpretation and overstaging of the carcinoma in these patients. We encountered such a scenario in an elderly female patient with distal esophageal squamous cell carcinoma patient, who developed F-18-fluorodeoxyglucose positron emission tomography avid left lobe liver lesion post neoadjuvant radiotherapy, simulating interval metastasis. A liver biopsy ruled out malignancy and helped to clinch the correct diagnosis of radiation induced liver injury.

A Rare Case of Radiation-Induced Liver Disease in Treated Abdominal Lymphoma Showing High [18F]FDG Avidity and Low EOB Uptake Proportional to the Irradiation Dose

A 44-year-old woman presented with high [¹⁸F]FDG uptake liver lesion after six courses of R-CHOP and radiotherapy for abdominal DLBCL, which was misdiagnosed as a hepatic invasion. EOB–MRI showed slight T2 hyperintensity, low-intensity DWI, and decreased EOB uptake in the hepatocellular phase. Compared with the pretreatment planning CT, the liver lesion coincided with the area of >40.5 Gy, resulting in the diagnosis of RILD. At the follow-up [¹⁸F]FDG PET/CT 7 months after irradiation, the abnormal liver uptake disappeared. Comparing [¹⁸F]FDG PET/CT, EOB–MRI, and planning CT can lead to the correct diagnosis of RILD and avoid unnecessary biopsies and treatment changes.

Pitfalls and Pearls in Esophageal Carcinoma

The management of patients with esophageal carcinoma (EC) requires accurate clinical staging and post-therapeutic evaluation. Currently, esophagogastroduodenoscopy/endoscopic ultrasound (EGD/EUS), endoscopic ultrasound-fine needle aspiration (EUS-FNA), computed tomography (CT), 18F- fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) and magnetic resonance (MR) imaging are used for the initial clinical staging, evaluation of therapeutic response and follow-up in patients with EC. However, there are limitations and pitfalls that are commonly encountered when imaging these patients that can limit accurate assessment. Knowledge of the limitations and pitfalls associated with the use of these different imaging modalities is essential in avoiding misinterpretation and guaranteeing the appropriate management for patient with EC.

Surveillance Following Treatment of Esophageal Cancer

We describe the surveillance strategies after esophageal cancer treatment, whether local therapy, induction chemoradiation, or other definitive treatment such as trimodality therapy. We discuss the shortcomings of the different invasive and imaging studies, and the recommended stage-specific surveillance after local and organ-sparing approaches to esophageal cancer treatment.

Correlation between microvessel density (MVD) and multi-spiral CT (MSCT) perfusion parameters of esophageal cancer lesions and the diagnostic value of combined CtBP2 and P16INK4A

Background

This article aims to analyze the correlation between microvessel density (MVD) and multi-spiral CT(MSCT) perfusion parameters of esophageal cancer lesions, and the diagnostic value of combining C-terminal binding protein 2 (CtBP2) and P16 inhibitor of cyclin-dependent kinase 4a (P16^INK4A).

Methods

A total of 42 cases of normal esophageal mucosa tissues >5 cm from the cancer tissue were selected as the control group. The expression levels of CtBP2 and P16^INK4A and the values of MSCT perfusion parameters and MVD were compared in the control group and esophageal cancer group. SP immunohistochemical staining was used to detect protein expression levels of CtBP2 and P16^INK4A. The Pearson method was used to analyze the differences and pertinence of MSCT perfusion parameters and MVD in the control group and esophageal cancer group. The receiver operating characteristic (ROC) curve was used to calculate the diagnostic value of CtBP2 and P16^INK4A combined with MVD and MSCT perfusion parameters in esophageal cancer.

Results

The positive expression rate of P16^INK4A in the esophageal cancer group was significantly lower than that in the control group. The positive expression rates of CtBP2, blood volume (BV), mean transit time (MTT), surface permeability (permeability surface, PS), and MVD values were significantly higher than those of the control group (P<0.05). There was no significant difference in blood flow (BF) value between the 2 groups (P>0.05). The BF value of the tumor invading the fibrous membrane was significantly higher than that of the non-invading fibrous membrane (P<0.05), and the PS and MVD values of the patients with lymph node metastasis were higher than those without lymph node metastasis (P<0.05). The MSCT perfusion parameters BF and BV were significantly positively correlated with MVD (P<0.05), while MTT, PS, and MVD were not significantly correlated (P>0.05). ROC results showed that the areas under curve (AUC) of CtBP2, P16^INK4A, and MSCT were 0.625, 0.747, and 0.812, respectively. However, the area under the combined detection curve was larger, at 0.869.

Conclusions

MSCT perfusion imaging of esophageal cancer lesions can indirectly reflect the angiogenesis of esophageal cancer, and the combination of CtBP2 and P16^INK4A can effectively improve the diagnostic efficiency of the disease.

PET/CT Variants and Pitfalls in Liver, Biliary Tract, Gallbladder and Pancreas

A wide variety of pathological anomalies may occur in the liver, biliary system, and pancreas. It is a necessity to use many different imaging techniques in order to distinguish such varied pathologies, especially those from malignant processes. Positron Emission Tomography/Computed Tomography (PET/CT) is an imaging method that has proven its diagnostic value in oncology and can be used for different clinical purposes. Fluoro-18 fluoro-2-deoxy-D-glucose has a wide range of uses as a dominant radiopharmaceutical in routine molecular imaging, however, molecular imaging has started to play a more important role in personalized cancer treatment in recent years with new Fluoro-18 and Gallium-68 labeled tracers. Although molecular imaging has a strong diagnostic effect, the surprises and pitfalls of molecular imaging can lead us to unexpected and misleading results. Prior to PET/CT analysis and reporting, information about possible technical and physiological pitfalls, normal histological features of tissues, inflammatory pathologies, specific clinical features of the case, treatment-related complications and past treatments should be evaluated in advance to avoid misinterpretation. In this review, the physiological and pathophysiological variants as well as pitfalls encountered in PET/CT imaging of the liver, biliary tract, gallbladder, and pancreas will be examined. Other benign and malignant pathologies that have been reported to date and that have led to incorrect evaluation will be listed. It is expected that the devices, software, and artificial intelligence applications that will be developed in the near future will enable much more effective and faster imaging that will reduce the potential causes of error. However, as a result of the dynamic and evolving structure of the information obtained by molecular imaging, the inclusion of the newly developed radiopharmaceuticals in routine practice will continue to carry new potentials as well as new troubles. Although molecular imaging will be the flagship of diagnostic oncology in the 21st century, the correct analysis and interpretation by the physician will continue to form the basis of achieving optimal performance.

Phantom simulation of liver metastasis on a positron emission tomography with computed tomography scan after neoadjuvant chemoradiotherapy for distal esophageal cancer: a case report

Background

Neoadjuvant chemoradiotherapy is currently the gold standard treatment for esophageal cancer prior to surgery. This radiation therapy will sometimes lead to liver damage parallel to esophageal lesions, which mimics liver metastasis visualized by ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography. In this report, we publish virtual radiation-induced liver damage images obtained during surgery, along with the coherent pathology, in order to confirm the false-positive result through an optimally decisive radiological examination.

Case presentation

We report a case of a Asian male patient with distal esophageal cancer who had undergone neoadjuvant chemoradiotherapy (5000 cGy). Subsequently, a new lesion was discovered during a positron emission tomography with computed tomography scan 6 weeks later, near the left caudate lobe of the liver during tumor restaging. To exclude the possibility of liver metastasis, serial imaging was conducted, which included liver sonography, computed tomography, and magnetic resonance imaging for a more intimate probe. The patient’s condition was verified as being liver inflammation change, as seen by the liver magnetic resonance imaging presentation. Thoracoscopic esophagectomy was performed with cervical esophagogastrostomy via the retrosternal route, along with a feeding jejunostomy. The procedure was performed smoothly, with an intraoperative liver biopsy also being conducted 2 weeks later, after positron emission tomography with computed tomography restaging. The pathology report revealed esophageal cancer in the form of poorly differentiated squamous cell carcinoma, pT3N1M0. The liver biopsy revealed obvious inflammation change after radiation therapy, which elucidated sinusoidal congestion with the attenuated hepatic cords and filled with erythrocytes. There was no evidence of liver metastasis. The patient recovered uneventfully and was discharged with his oral intake performing smoothly, and a stable condition was observed during 12 months of outpatient department follow-up.

Conclusions

New foci of increased ¹⁸F-fluorodeoxyglucose avidity are commonly seen in the caudate and left hepatic lobes of the liver during neoadjuvant chemoradiation for distal esophageal cancer, and these findings generally reflect radiation-induced liver disease rather than metastatic disease. Awareness of the pitfalls of a high ¹⁸F-fluorodeoxyglucose uptake in radiation-induced liver injury is crucial in order to avoid misinterpretation and overstaging. Except for the location of ¹⁸F-fluorodeoxyglucose uptake, the shape of the lesion, and an maximum standardized uptake value (> 10/h), a convincing liver magnetic resonance imaging scan or even a liver biopsy can provide accurate information for distinguishing radiotherapy-induced liver injury from liver metastasis.

A Case of Liver Injury Mimicking Metastasis After Gamma Knife Therapy for Lung Cancer: Evaluating by 18F-FDG PET/CT

A 52-year-old man presented a mixed low-density lesion with high FDG uptake in hepatic segment VIII after gamma knife therapy for lung cancer, which was easily misdiagnosed as hepatic metastasis. Follow-up PET/CT assessment demonstrated that the hepatic lesion was barely observed and without FDG accumulation 5 months after radiotherapy. This case suggests that a new FDG-avid lesion at PET/CT after radiotherapy for lung cancer can be caused by radiation-induced liver injury. Knowledge of its imaging characteristics and nature course evaluated by follow-up PET/CT is critical to avoid misinterpretation of this lesion as metastases.

Prediction and diagnosis of interval metastasis after neoadjuvant chemoradiotherapy for oesophageal cancer using 18F-FDG PET/CT

OBJECTIVE

During neoadjuvant chemoradiotherapy for oesophageal cancer, or in the interval prior to surgery, some patients develop systemic metastasis. This study aimed to evaluate the diagnostic performance of ¹⁸F-FDG PET/CT for the detection of interval metastasis and to identify predictors of interval metastases in a large cohort of oesophageal cancer patients.

METHODS

In total, 783 consecutive patients with potentially resectable oesophageal cancer who underwent chemoradiotherapy and pre- and post-treatment ¹⁸F-FDG PET/CT between 2006 and 2015 were analyzed from a prospectively maintained database. Diagnostic accuracy measures were calculated on a per-patient basis using histological verification or clinical follow-up as a reference standard. Multivariable logistic regression analysis was performed to determine pre-treatment predictors of interval metastasis. A prediction score was developed to predict the probability of interval metastasis.

RESULTS

Of 783 patients that underwent ¹⁸F-FDG PET/CT restaging, 65 (8.3%) were found to have interval metastasis and 44 (5.6%) were deemed to have false positive lesions. The resulting sensitivity and specificity was 74.7% (95% CI: 64.3-83.4%) and 93.7% (95% CI: 91.6-95.4%), respectively. Multivariable analysis revealed that tumor length, cN status, squamous cell tumor histology, and baseline SUV_max were associated with interval metastasis. Based on these criteria, a prediction score was developed with an optimism adjusted C-index of 0.67 that demonstrated accurate calibration.

CONCLUSIONS

¹⁸F-FDG PET/CT restaging detects distant interval metastases in 8.3% of patients after chemoradiotherapy for oesophageal cancer. The provided prediction score may stratify risk of developing interval metastasis, and could be used to prioritize additional restaging modalities for patients most likely to benefit.