Hepatobiliary phase enhancement of liver metastases on gadoxetic acid MRI: assessment of frequency and patterns

MRI findings of newly present benign focal hepatic observations following chemotherapy: distinct features in early- and late-term follow-up

OBJECTIVE

To evaluate gadoxetic acid-enhanced (Gd-EOB-DTPA) MRI features of newly detected benign focal hepatic observations after chemotherapy.

METHODS

In this retrospective single-center case-control study, we enrolled a cohort of 43 cancer patients with 93 newly detected benign focal hepatic observations after chemotherapy between January 2010 and December 2020. We evaluated several parameters including the delay of occurrence after chemotherapy, imaging features, and imaging follow-up. These parameters were compared with those observed in a control group comprising 34 patients with 93 hepatic metastases.

RESULTS

For focal hepatic observations occurring at early-term follow-up (delay of occurrence after chemotherapy, median 3 months, range 1-6 months) with 22 patients encompassing 45 lesions, most lesions exhibited an ill-defined margin on HBP images (64.4%), negative on diffusion-weighted images (84.4%), mottled hypo-intensity on hepatobiliary phase images (88.9%), and undistorted vessels traversing the lesions (80.0%). Follow-up imaging indicated that 91.9% of these lesions resolved within 4-20 months. For focal hepatic observations occurring at late-term follow-up (delay of occurrence after chemotherapy, median 34 months, range 12-60 months) with 21 patients encompassing 48 lesions, which were diagnosed as focal nodular hyperplasia (FNH)-like lesions based on MRI features. A hepatobiliary ring enhancement was observed in 56.3% of lesions, and 66.7% of patients showed an increase in lesion size and/or number during follow-up imaging.

CONCLUSION

Focal hepatic observations occurring at early-term and late-term follow-ups after chemotherapy have distinctive imaging features at Gd-EOB-DTPA-MRI. Early-term focal observations tend to resolve spontaneously, whereas FNH-like lesions can increase in size and number during follow-up.

KEY POINTS

Question Focal benign liver lesions related to chemotherapy-induced hepatic injury were reported in recent years, often leading to confusion with metastasis and resulting in misdiagnosis. Findings Chemotherapy-induced focal hepatic observations identified during early- and late-term follow-up exhibit distinct imaging characteristics on Gd-EOB-DTPA-MRI and demonstrate varying temporal changes. Clinical relevance Chemotherapy-induced hepatic observations can be differentiated from metastasis based on Gd-EOB-DTPA MRI findings and their temporal changes. A deeper understanding of their findings can avoid unnecessary biopsies or surgical resections.

CT-based liver peritumoural radiomics features predict hepatic metastases sources as gastrointestinal or non-gastrointestinal

OBJECTIVES

To investigate the feasibility of radiomics models for predicting the source of hepatic metastases from gastrointestinal (GI) vs non-gastrointestinal (non-GI) primary tumours on contrast-enhanced CT (CECT).

METHODS

Three hundred and forty-seven patients with liver metastases (180 from GI and 167 from non-GI) and abdominal CECT including arterial, portal venous, and delayed phases were divided into training (221) and validation (96) sets at a ratio of 7:3 and an independent testing set (30). Radiomics features were extracted from volumes of interest (VOIs) including tumoural (Vtc) and peritumoural (Vpt) regions on CECT. Optimal radiomics features were used in logistic regression models using receiver operating curve (ROC) analysis to evaluate the diagnostic efficiency.

RESULTS

The best single-phase model was a venous phase peritumoural VOI with 11 features. Area under the curve (AUC), sensitivity, and specificity were 0.817, 0.740, and 0.761, respectively in the validation set. While the best arterial phase tumoural VOI gave an AUC of 0.677 in the validation set. For the combined models, peritumoural VOI in arterial and venous phases (15 features) achieved the best prediction performance with an AUC of 0.926 in the validation set and 0.884 in the testing set.

CONCLUSION

Liver peritumoural radiomics features extracted from CECT were able to identify the source of hepatic metastases as GI vs non-GI.

ADVANCES IN KNOWLEDGE

Peritumoural radiomics features showed a correlation with source of liver metastases. The radiomics features from liver peritumoural arterial and venous phases CT were promising in differentiating the source of hepatic metastases from GI vs non-GI primary tumours.

Gadoxetic acid-enhanced MRI for the detection of liver metastases from melanoma

PURPOSE

We aimed to assess imaging findings and detection sensitivity for melanoma liver metastases on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

METHODS

This retrospective study included patients with melanoma liver metastasis who underwent gadoxetic acid-enhanced MRI. Two abdominal radiologists independently evaluated signal characteristics of liver metastases on morphologic imaging (precontrast T1- and T2-weighted imaging), diffusion-weighted imaging (DWI), dynamic imaging, and hepatobiliary phase (HBP). Imaging findings were compared according to detection on HBP and the primary site of the melanoma using logistic regression with the generalized estimating equation (GEE). Detection sensitivity for metastases was compared among different MR imaging sets using logistic regression with GEE.

RESULTS

A total of 67 patients with 254 liver metastases were included (44 women; mean age ± standard deviation, 65.6 ± 13.0 years). On HBP, 76.0% of metastases were detected, and 55.5% (141/254) showed hypointensity. Most of the metastases that were not detected on HBP originated from ocular melanomas (98.4%, 60/61), ≤1 cm (90.2%, 55/61) and showed T1 hyperintensity (98.4%, 60/61). Metastases from non-ocular melanomas more frequently showed T1 hypointensity, T2 hyperintensity, diffusion restriction, arterial enhancement, and HBP hypointensity than those from ocular melanomas (Ps ≤ 0.019). The detection sensitivity of HBP (76.0%) was significantly higher than DWI (65.7%, P = 0.006), but lower than morphologic imaging (98.8%, P < 0.001) and dynamic imaging (97.6%, P < 0.001).

CONCLUSION

The detection sensitivity of HBP for melanoma liver metastasis was 76.0%, which was lower than that of morphologic or dynamic imaging. HBP of gadoxetic acid-enhanced MRI has little advantage in detecting melanoma liver metastases.

Development of Dual Diagnostic-Therapeutic Nanoformulation Effective Against Pancreatic Cancer in Animal Model

Purpose

Erythrocytes and fibroblasts in the pancreatic cancer tumor microenvironment promote tumor cell growth and invasion by providing nutrients and promoting immunosuppression. Additionally, they form a barrier against the penetration of chemotherapeutic drugs. Therefore, the search for diversified tumor-targeting materials plays an essential role in solving the above problems.

Methods

Physicochemical characterization of Graphene fluorescent nanoparticles (GFNPs) and nanomedicines were analyzed by transmission electron microscopy (TEM), elemental analyzers and ultraviolet fluorescence (UV/FL) spectrophotometer. Localization of GFNPs in cell and tissue sections imaged with laser confocal microscope, fluorescence scanner and small animal in vivo imager. Qualitative detection and quantitative detection of GFNPs and GFNPs-GEM were performed using High performance liquid chromatography (HPLC).

Results

Based on the 3 nm average dimensions, GFNPs penetrate vascular endothelial cells and smooth muscle cells, achieve up to label 30% tumor cells and 60% cancer-associated fibroblasts (CAFs) cells, and accurately label mature red blood cells in the tumor microenvironment. In orthotopic transplanted pancreatic cancer models, the fluorescence intensity of GFNPs in tumors showed a positive correlation with the cycle size of tumor development. The differential spatial distribution of GFNPs in three typical clinical pancreatic cancer samples demonstrated their diagnostic potential. To mediate the excellent targeting properties of GFNPs, we synthesized a series of nanomedicines using popular chemotherapeutic drugs, in which complex of GFNPs and gemcitabine (GFNPs-GEM) possessed stability in vivo and exhibited effective reduction of tumor volume and fewer side effects.

Conclusion

GFNPs with multiple targeting tumor microenvironments in pancreatic cancer possess diagnostic efficiency and therapeutic potential.

Preoperative MRI radiomic analysis for predicting local tumor progression in colorectal liver metastases before microwave ablation

PURPOSE

Radiomics may aid in predicting prognosis in patients with colorectal liver metastases (CLM). Consistent data is available on CT, yet limited data is available on MRI. This study assesses the capability of MRI-derived radiomic features (RFs) to predict local tumor progression-free survival (LTPFS) in patients with CLMs treated with microwave ablation (MWA).

METHODS

All CLM patients with pre-operative Gadoxetic acid-MRI treated with MWA in a single institution between September 2015 and February 2022 were evaluated. Pre-procedural information was retrieved retrospectively. Two observers manually segmented CLMs on T2 and T1-Hepatobiliary phase (T1-HBP) scans. After inter-observer variability testing, 148/182 RFs showed robustness on T1-HBP, and 141/182 on T2 (ICC > 0.7).Cox multivariate analysis was run to establish clinical (CLIN-mod), radiomic (RAD-T1, RAD-T2), and combined (COMB-T1, COMB-T2) models for LTPFS prediction.

RESULTS

Seventy-six CLMs (43 patients) were assessed. Median follow-up was 14 months. LTP occurred in 19 lesions (25%).CLIN-mod was composed of minimal ablation margins (MAMs), intra-segment progression and primary tumor grade and exhibited moderately high discriminatory power in predicting LTPFS (AUC = 0.89, p = 0.0001). Both RAD-T1 and RAD-T2 were able to predict LTPFS: (RAD-T1: AUC = 0.83, p = 0.0003; RAD-T2: AUC = 0.79, p = 0.001). Combined models yielded the strongest performance (COMB-T1: AUC = 0.98, p = 0.0001; COMB-T2: AUC = 0.95, p = 0.0003). Both combined models included MAMs and tumor regression grade; COMB-T1 also featured 10th percentile of signal intensity, while tumor flatness was present in COMB-T2.

CONCLUSION

MRI-based radiomic evaluation of CLMs is feasible and potentially useful for LTP prediction. Combined models outperformed clinical or radiomic models alone for LTPFS prediction.

Comparison of 68Ga-DOTATATE Positron Emmited Tomography/Computed Tomography and Gadoxetic Acid-Enhanced Magnetic Resonance Imaging for the Detection of Liver Metastases from Well-Differentiated Neuroendocrine Tumors

This study aimed to compare the detection of neuroendocrine tumor liver metastases (NLMs) in hepatobiliary-specific contrast-enhanced MRI (pMR) versus 68Ga-DOTATATE PET/CT (DT-PET). This retrospective study cohort included 30 patients with well-differentiated neuroendocrine tumors who underwent both DT-PET and pMR. Two readers independently assessed NLMs count, SUVmax on DT-PET, and signal characteristics on pMR. A consensus review by two additional readers resolved discrepancies between the modalities. Results showed concordance between DT-PET and pMR NLM count in 14/30 patients (47%). pMR identified more NLMs in 12/30 patients (40%), of which 4 patients showed multiple deposits on pMR but only 0-1 lesions on DT-PET. DT-PET detected more in 4/30 patients (13%). Overall, pMR detected more metastases than DT-PET (p = 0.01). Excluding the four outliers, there was excellent agreement between the two methods (ICC: 0.945, 95%CI: 0.930, 0.958). Notably, pMR had a higher NLM detection rate than DT-PET, with correlations found between lesion size on pMR and DT-PET detectability, as well as diffusion restriction on pMR and SUVmax on DT-PET. In conclusion, in consecutive patients with well-differentiated NETs, the detection rate of NLM is higher with pMR than with DT-PET. However, when excluding patients whose tumors do not overexpress somatostatin receptors (13% of the cohort), high concordance in the detection of NLM is observed between DT PET and pMR.

Gadoxetic acid in hepatocellular carcinoma and liver metastases: pearls and pitfalls

Gadoxetic disodium (Primovist) is a hepatocyte-specific magnetic resonance imaging (MRI) contrast agent with increasing popularity with its unique dual dynamic and excretory properties in focal liver lesion detection and characterisation. In-depth knowledge of its diagnostic utility and pitfalls in hepatocellular carcinoma (HCC) and liver metastases is crucial in facilitating clinical management. The current article reviews the pearls and pitfalls in these aspects with highlights from the latest research evidence. Pearls for common usage of Primovist in HCC includes detection of precursor cancer lesions in cirrhotic patients. Hepatobiliary phase hypointensity precedes arterial phase hyperenhancement (APHE) in hepatocarcinogenesis. Hepatobiliary phase hypointense nodules without APHE can represent early or progressed hepatocellular carcinoma (HCC) and high-grade dysplastic nodules. In addition, Primovist is useful to differentiate HCC from pseudolesions. Pitfalls in diagnosing HCC include transient tachypnoea in the arterial phase, rare hepatobiliary phase hyperintense HCC, and decompensated liver cirrhosis compromising image quality. Primovist is currently the most sensitive technique in diagnosing liver metastases before curative hepatic resection. Other patterns of enhancement of liver metastases, "disappearing" liver metastases are important pitfalls. Radiologists should be aware of the diagnostic utility, limitations, and potential pitfalls for the common usage of hepatobiliary specific contrast agent in liver MRI.

Pancreatic neuroendocrine neoplasms: a 2022 update for radiologists

Pancreatic neuroendocrine neoplasms (PaNENs) are a unique group of pancreatic neoplasms with a wide range of clinical presentations and behaviors. Given their heterogeneous appearance and increasing detection on cross-sectional imaging, it is essential that radiologists understand the variable presentation and distinctions PaNENs display compared to other pancreatic neoplasms. Additionally, some of these neoplasms may be hormonally functional, and it is imperative that radiologists be aware of the common clinical presentations of hormonally active PaNENs. Knowledge of PaNEN pathology and treatments may influence which imaging modality is optimal for each patient. Each imaging modality used for PaNENs has distinct advantages and disadvantages, particularly in different treatment settings. Thus, the focus of this manuscript is to provide an update for the radiologist on PaNEN pathology, imaging, and treatments.

Radiological Imaging of Gastro-Entero-Pancreatic Neuroendocrine Tumors. The Review of Current Literature Emphasizing the Diagnostic Value of Chosen Imaging Methods

Despite development of radiologic imaging, detection and follow-up of neuroendocrine neoplasms (NENs) still pose a diagnostic challenge, due to the heterogeneity of NEN, their relatively long-term growth, and small size of primary tumor. A set of information obtained by using different radiological imaging tools simplifies a choice of the most appropriate treatment method. Moreover, radiological imaging plays an important role in the assessment of metastatic lesions, especially in the liver, as well as, tumor response to treatment. This article reviews the current, broadly in use imaging modalities which are applied to the diagnosis of GEP-NETs, (the most common type of NENs) and put emphasis on the strengths and limitations of each modality.