Quantitative assessment of global hepatic glycolysis in patients with cirrhosis and normal controls using 18F-FDG-PET/CT: a pilot study

Imaging diabetic cardiomyopathy in a type 1 diabetic rat model using 18F-FEPPA PET

OBJECTIVE

Diabetic patients often experience chronic inflammation and fibrosis in their cardiac tissues, highlighting the pressing need for the development of sensitive diagnostic methods for longitudinal assessment of diabetic cardiomyopathy. This study aims to evaluate the significance of an inflammatory marker known as translocator protein (TSPO) in a positron emission tomography (PET) protocol for longitudinally monitoring cardiac dysfunction in a diabetic animal model. Additionally, we compared the commonly used radiotracer, 18F-fluoro-2-deoxy-d-glucose (18F-FDG).

METHODS

Fourteen 7-week-old female Sprague-Dawley rats were used in this study. Longitudinal PET experiments were conducted using 18F-N-2-(2-fluoroethoxy)benzyl)-N-(4-phenoxypyridin-3-yl)acetamide (18F-FEPPA) (n = 3), the TSPO radiotracer, and 18F-FDG (n = 3), both before and after the onset of diabetes. Histological and immunohistochemical staining assays were also conducted in both the control (n = 4) and diabetes (n = 4) groups.

RESULTS

Results indicated a significant increase in cardiac tissue uptake of 18F-FEPPA after the onset of diabetes (P < 0.05), aligning with elevated TSPO levels observed in diabetic animals according to histological data. Conversely, the uptake of 18F-FDG in cardiac tissue significantly decreased after the onset of diabetes (P < 0.05).

CONCLUSION

These findings suggest that 18F-FEPPA can function as a sensitive probe for detecting chronic inflammation and fibrosis in the cardiac tissues of diabetic animals.

Predicting Outcome after Percutaneous Ablation for Early-Stage Hepatocellular Carcinoma Using Various Imaging Modalities

Percutaneous ablation is a low-invasive, repeatable, and curative local treatment that is now recommended for early-stage hepatocellular carcinoma (HCC) that is not suitable for surgical resection. Poorly differentiated HCC has high-grade malignancy potential. Microvascular invasion is frequently seen, even in tumors smaller than 3 cm in diameter, and prognosis is poor after percutaneous ablation. Biopsy has a high risk of complications such as bleeding and dissemination; therefore, it has limitations in determining HCC tumor malignancy prior to treatment. Advances in diagnostic imaging have enabled non-invasive diagnosis of tumor malignancy. We describe the usefulness of ultrasonography, computed tomography, magnetic resonance imaging, and 18F-fluorodeoxyglucose positron emission tomography for predicting outcome after percutaneous ablation for HCC.

Comparison of 18F-FDG, 18F-Fluoroacetate, and 18F-FEPPA for Imaging Liver Fibrosis in a Bile Duct-Ligated Rat Model

Developing sensitive diagnostic methods for a longitudinal evaluation of the status of liver fibrosis is a priority. This study is aimed at assessing the significance of longitudinal positron emission tomography (PET) imaging with ¹⁸F-labeling tracers for assessing liver fibrosis in a rat model with bile duct ligation (BDL). Twenty-one 6-week-old Sprague-Dawley male rats were used in this study. Longitudinal PET images using [¹⁸F]N-2-(2-fluoroethoxy)benzyl)-N-(4-phenoxypyridin-3-yl)acetamide ([¹⁸F]FEPPA) (n = 3), [¹⁸F]fluoroacetate ([¹⁸F]FAc) (n = 3), and 18F-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) (n = 3) were obtained at 0, 1, and 2 weeks after BDL. Biochemical assays, histological assays, immunohistochemical staining assays, and next generation sequencing analyses were also performed at 0 (n = 3), 1 (n = 3), 2 (n = 3), and 3 (n = 3) weeks after BDL, which demonstrated the severe damage in rat livers after BDL. Regarding [¹⁸F]FEPPA and [¹⁸F]FDG, there was a significantly higher uptake in the liver after BDL (both P < 0.05), which lasted until week 2. However, the uptake of [¹⁸F]FAc in the liver was not significantly different before and after BDL (P = 0.28). Collectively, both [¹⁸F]FEPPA and [¹⁸F]FDG can serve as sensitive probes for detecting the liver fibrosis. However, [¹⁸F]FAc is not recommended to diagnose liver fibrosis.

Cell death PET/CT imaging of rat hepatic fibrosis with 18F-labeled small molecule tracer

PURPOSE

To evaluate the potential feasibility of Al[¹⁸F]F-1,4,7-triazacyclononane-1,4,7-triaceticacid (NOTA)-tripolyethylene glycol (PEG₃)-Duramycin (Al[¹⁸F]F-NOTA-PEG₃-Duramycin) positron emission tomography (PET) for imaging of rat hepatic fibrosis.

PROCEDURES

Hepatic fibrosis rat models were injected with thioacetamide (TAA), control rats received saline (n = 12 per group). Rats in the two groups underwent PET imaging using Al[¹⁸F]F-NOTA-PEG₃-Duramycin and [¹⁸F]FDG at multiple time points (2, 4, 6, and 8 weeks after TAA or saline treatment). Between-group differences in the apoptosis rate, fibrotic activity, and liver uptake of Al[¹⁸F]F-NOTA-PEG₃-Duramycin or [¹⁸F]FDG were assessed using Student's t-test. Imaging results were cross-validated using histopathology detection and Pearson's correlation test was used to assess the association relationships between radioactive uptake value and quantified histopathological data.

RESULTS

Compared with control group at multiple time points, each TAA group showed a higher radioactive liver uptake of Al[¹⁸F]F-NOTA-PEG₃-Duramycin (each P < 0.05). Furthermore, the increase in the liver uptake of Al[¹⁸F]F-NOTA-PEG₃-Duramycin was proportional to the progression of fibrosis (R² = 0.8846, P < 0.001) and apoptosis rate (R² = 0.9208, P < 0.001) in the TAA group. Meanwhile, there were also between-group differences in [¹⁸F]FDG uptake in each phase (P < 0.05), however, no relationship between [¹⁸F]FDG uptake and the fibrotic activity was observed.

CONCLUSIONS

Al[¹⁸F]F-NOTA-PEG₃-Duramycin PET/CT could be applied to monitor the progression of liver fibrosis, whereas [¹⁸F]FDG PET/CT could not. Implications of this work for noninvasive diagnosis of liver fibrosis, assessment of fibrotic activity, and evaluation of antifibrotic therapy are expected.

Radiomics based on fluoro-deoxyglucose positron emission tomography predicts liver fibrosis in biopsy-proven MAFLD: a pilot study

Rationale: Since non-invasive tests for prediction of liver fibrosis have a poor diagnostic performance for detecting low levels of fibrosis, it is important to explore the diagnostic capabilities of other non-invasive tests to diagnose low levels of fibrosis. We aimed to evaluate the performance of radiomics based on ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) in predicting any liver fibrosis in individuals with biopsy-proven metabolic dysfunction-associated fatty liver disease (MAFLD). Methods: A total of 22 adults with biopsy-confirmed MAFLD, who underwent ¹⁸F-FDG PET/CT, were enrolled in this study. Sixty radiomics features were extracted from whole liver region of interest in ¹⁸F-FDG PET images. Subsequently, the minimum redundancy maximum relevance (mRMR) method was performed and a subset of two features mostly related to the output classes and low redundancy between them were selected according to an event per variable of 5. Logistic regression, Support Vector Machine, Naive Bayes, 5-Nearest Neighbor and linear discriminant analysis models were built based on selected features. The predictive performances were assessed by the receiver operator characteristic (ROC) curve analysis. Results: The mean (SD) age of the subjects was 38.5 (10.4) years and 17 subjects were men. 12 subjects had histological evidence of any liver fibrosis. The coarseness of neighborhood grey-level difference matrix (NGLDM) and long-run emphasis (LRE) of grey-level run length matrix (GLRLM) were selected to predict fibrosis. The logistic regression model performed best with an AUROC of 0.817 [95% confidence intervals, 0.595-0.947] for prediction of liver fibrosis. Conclusion: These preliminary data suggest that ¹⁸F-FDG PET radiomics may have clinical utility in assessing early liver fibrosis in MAFLD.

Prospective Evaluation of 18F-DCFPyL PET/CT in Detection of High-Risk Localized Prostate Cancer: Comparison With mpMRI

OBJECTIVE. The purpose of this study was to assess the utility of PET with (2S)-2-[[(1S)-1-carboxy-5-[(6-(¹⁸F)fluoranylpyridine-3-carbonyl)amino]pentyl]carbamoylamino]pentanedioic acid (¹⁸F-DCFPyL), a prostate-specific membrane antigen (PSMA)-targeted radiotracer, in the detection of high-risk localized prostate cancer as compared with multiparametric MRI (mpMRI). SUBJECTS AND METHODS. This HIPAA-compliant prospective study included 26 consecutive patients with localized high-risk prostate cancer (median age, 69.5 years [range, 53-81 years]; median prostate-specific antigen [PSA] level, 18.88 ng/mL [range, 1.03-20.00 ng/mL]) imaged with ¹⁸F-DCFPyL PET/CT and mpMRI. Images from PET/CT and mpMRI were evaluated separately, and suspicious areas underwent targeted biopsy. Lesion-based sensitivity and tumor detection rate were compared for PSMA PET and mpMRI. Standardized uptake value (SUV) and PSMA PET parameters were correlated with histopathology score, and uptake in tumor was compared with that in nonmalignant tissue. On a patient level, SUV and PSMA tumor volume were correlated with PSA density. RESULTS. Forty-four tumors (one in Gleason grade [GG] group 1, 12 in GG group 2, seven in GG group 3, nine in GG group 4, and 15 in GG group 5) were identified at histopathology. Sensitivity and tumor detection rate of ¹⁸F-DCFPyL PET/CT and mpMRI were similar (PET/CT, 90.9% and 80%; mpMRI, 86.4% and 88.4%; p = 0.58/0.17). Total lesion PSMA and PSMA tumor volume showed a relationship with GG (τ = 0.27 and p = 0.08, τ = 0.30 and p = 0.06, respectively). Maximum SUV in tumor was significantly higher than that in nonmalignant tissue (p < 0.05). Tumor burden density moderately correlated with PSA density (r = 0.47, p = 0.01). Five true-positive tumors identified on ¹⁸F-DCFPyL PET/CT were not identified on mpMRI. CONCLUSION. In patients with high-risk prostate cancer, ¹⁸F-DCFPyL PET/CT is highly sensitive in detecting intraprostatic tumors and can detect tumors missed on mpMRI. Measured uptake is significantly higher in tumor tissue, and PSMA-derived tumor burden is associated with severity of disease.

Pilot Study to Diagnose Nonalcoholic Steatohepatitis With Dynamic 18F-FDG PET

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are major causes of chronic liver disease characterized by steatosis, inflammation, and fibrosis. Diagnosis of inflammation is limited by the need for liver biopsy. Dynamic PET with the widely used radiotracer ¹⁸F-FDG provides a novel method for evaluating spatial and temporal changes in liver inflammation.

MATERIALS AND METHODS

Patients with NAFLD or NASH underwent dynamic FDG PET and MRI within 6 months of undergoing liver biopsy. Liver time-activity curves were extracted to estimate kinetic parameters representing various rate constants of FDG transport using tracer kinetic modeling. Liver biopsy specimens were scored on the basis of NASH Clinical Research Network criteria.

RESULTS

This pilot study included 22 patients, 14 of whom were women. Patient age ranged from 18 to 70 years, and the mean body mass index (weight in kilograms divided by the square of height in meters) was 33.2 (range, 24-43.1). The K₁ value, which represents the rate of FDG transport from blood to hepatic tissue, was significantly correlated with inflammation (r = -0.7284; p = 0.0001) and the overall NAFLD activity score (NAS; r = -0.6750; p = 0.0006). K₁ values were inversely related to the hepatic inflammation score and NAS. Although heterogeneity in K₁ values across eight liver segments was noted, distinct segregation existed among segmental K₁ values dependent on the histologic inflammation score (p = 0.022) or NAS (p = 0.0091). K₁ had a strong association with both inflammation (ROC AUC value, 0.88) and the NAS (ROC AUC value, 0.89), with K₁ = 1.02 (mL/min/mL) corresponding to a sensitivity and specificity of 93% and 88%, respectively, for the NAS.

CONCLUSION

Dynamic FDG PET with tracer kinetic modeling has the potential to determine liver inflammation in patients with NAFLD and NASH and can fill an essential gap in diagnosis.

In vivo confirmation of altered hepatic glucose metabolism in patients with liver fibrosis/cirrhosis by 18F-FDG PET/CT

OBJECTIVE

The aim of this study was to assess the value of ¹⁸F-FDG PET/CT for quantitative assessment of hepatic metabolism in patients with different stages of liver fibrosis/cirrhosis.

MATERIALS AND METHODS

¹⁸F-FDG PET/CT scans of 37 patients either with or without liver fibrosis/cirrhosis, classified according to the METAVIR score (F0-F4) obtained from histopathological analysis of liver specimen, were analyzed retrospectively and classified as follows: no liver fibrosis (F0, n = 6), mild liver fibrosis (F1, n = 11), advanced liver fibrosis (F2, n = 6), severe liver fibrosis (F3, n = 5), and liver cirrhosis (F4, n = 11). The liver-to-blood ratio (LBR, scan time corrected for a reference time of 75 min) was compared between patient groups.

RESULTS

Patients with liver fibrosis or cirrhosis (≥ F1; LBR 1.53 ± 0.35) showed a significant higher LBR than patients with normal liver parenchyma (F0, 1.08 ± 0.23; P = 0.004). In direct comparison, LBR increased up to the advanced stage of liver fibrosis (F2; 2.00 ± 0.40) and decreased until liver cirrhosis is reached (F4, 1.32 ± 0.14).

CONCLUSION

Functional changes in liver parenchyma during liver fibrosis/cirrhosis affect hepatic glucose metabolism and significantly differ between stages of liver fibrosis/cirrhosis, classified according to the METAVIR scoring system, as demonstrated by LBR quantification by ¹⁸F-FDG PET/CT.

Feasibility of Preoperative FDG PET/CT Total Hepatic Glycolysis in the Remnant Liver for the Prediction of Postoperative Liver Function

OBJECTIVE

The objective of our study was to investigate the prognostic value of total glycolysis of the remnant liver, which reflects both metabolic and anatomic liver function, for predicting postoperative hepatic insufficiency.

MATERIALS AND METHODS

Patients who underwent ¹⁸F-FDG PET/CT and abdominal CT within 1 month of major hepatectomy were retrospectively analyzed. Total liver volume, remnant liver volume, the ratio of the remnant hepatic volume to the preoperative hepatic volume (RFRHV), and mean standardized uptake value (SUV_mean) were measured, and total glycolysis of the remnant liver was calculated. Clinical hepatic function reserve values, including the indocyanine green retention rate at 15 minutes, the model for end-stage liver disease (MELD) score, and aspartate aminotransferase to platelet ratio index (APRI), were calculated. Univariate and multivariate analyses were performed, and an optimal model for predicting hepatic insufficiency was developed. ROC curves were used to compare diagnostic performance.

RESULTS

Of 149 patients, seven patients had hepatic insufficiency. The SUV_mean showed the highest sensitivity (100%; specificity, 31.7%) for predicting hepatic insufficiency, and total glycolysis of the remnant liver showed the highest specificity (96.5%; sensitivity, 57.1%) for predicting hepatic insufficiency. On multivariate analysis, the odds ratio of APRI (> 5.4) and total glycolysis of the remnant liver (≤ 625.6) was 46.3 and 82.9, respectively, for predicting hepatic insufficiency. On ROC curve analysis, a new model composed of APRI and total glycolysis of the remnant liver showed a higher area under the ROC curve (A_z) value (A_z = 0.899) than SUV_mean (0.659), MELD score (0.618), APRI (0.693), RFRHV (0.797), and remnant liver volume (0.762).

CONCLUSION

The total glycolysis of the remnant liver has moderate sensitivity and high specificity for predicting hepatic insufficiency. Combining the total glycolysis of the remnant liver and APRI yielded the best diagnostic performance for predicting hepatic insufficiency.

Shear wave elastography in the evaluation of liver fibrosis in children

BACKGROUND

Shear-wave elastography (SWE) is a novel noninvasive method that involves application of local mechanical compression on soft tissue using focused ultrasonography and acquiring strain images that show tissue response. In this study, our goal was to assess the performance of SWE in the staging of liver fibrosis in children with chronic liver disease.

METHODS

The study involved measuring SWE values in the right lobe of the liver in a patient group of 76 children with chronic liver disease and a control group of 50 healthy subjects. In the patient group, the shear elastic modulus values were correlated with biopsy results according to the Brunt scoring system (F0: portal fibrosis, F1: perisinusoidal or portal/periportal fibrosis, F2: both perisinusoidal and portal/periportal fibrosis, F3: bridging fibrosis, and F4: cirrhosis). Performance of SWE in estimating liver fibrosis in children was determined based on a receiver-operating characteristics (ROC) analysis.

RESULTS

Mean SWE values of the control group and F0 group were not statistically significantly different (P = 0.106). The mean SWE values of the F1, F2, F3, and F4 groups were higher than that of the control group (all P < 0.001). Based on kiloPascal measurement values, the area under the ROC curve was 95.2% (95% confidence interval [CI] 92.1-99.5), with a sensitivity for diagnosing liver fibrosis of 91.5%, a specificity of 94.0%, a positive predictive value of 93.1%, and a negative predictive value of 92.6%. Based on meter-per-second measurement values, the area under the ROC curve was 96.3% (95% CI 92.7-99.8), with a sensitivity for diagnosing liver fibrosis of 93.2%, a specificity of 94.0%, a positive predictive value of 93.2%, and a negative predictive value of 94.0%. Mean SWE values for patients with nonalcoholic steatohepatitis were higher than those in the remainder of the study group.

CONCLUSIONS

Although liver fibrosis can be detected using SWE, differentiation of fibrosis stages could not be achieved. The presence of steatosis significantly increased the mean SWE values on elastography and so care should be taken when assessing children with nonalcoholic steatohepatitis.

FDG PET/CT in Crohn's disease: correlation of quantitative FDG PET/CT parameters with clinical and endoscopic surrogate markers of disease activity

PURPOSE

The aim of this study was to determine the feasibility and potential clinical utility of assessment of Crohn's disease (CD) activity by (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT employing a new quantitative approach.

METHODS

A total of 22 subjects (mean age 37) with CD who had undergone FDG PET/CT followed by ileocolonoscopy within 1 week were included in this analysis. The CD endoscopy index of severity (CDEIS) for various bowel segments was calculated. The CD activity index (CDAI) was evaluated, and fecal calprotectin was measured. On PET, regions with increased FDG uptake in large bowel were segmented with an adaptive contrast-oriented thresholding algorithm, and metabolically active volume (MAV), uncorrected mean standardized uptake value (SUV(mean)), partial volume-corrected SUV(mean) (PVC-SUV(mean)), SUV(max), uncorrected total lesion glycolysis (TLG = MAV × SUV(mean)), and PVC total lesion glycolysis (PVC-TLG = MAV × PVC-SUV(mean)) were measured. Global CD activity score (GCDAS) was calculated as the sum of PVC-TLG over all clinically significant FDG-avid regions in each subject. Correlations between regional PET quantification measures (SUVs, TLGs) and CDEIS were calculated. Correlations between the global PET quantification measure (GCDAS, global SUVs) with CDAI, fecal calprotectin, CDEIS, and CRP level were also calculated.

RESULTS

SUV(max), PVC-SUV(mean), and PVC-TLG significantly correlated with segment CDEIS subscores (r = 0.50, r = 0.69, and r = 0.31, respectively; p < 0.05). GCDAS significantly correlated with CDAI and fecal calprotectin (r = 0.64 and r = 0.51, respectively; p < 0.05).

CONCLUSION

By employing this new quantitative approach, we were able to calculate indices of regional and global CD activity, which correlated well with both clinical and pathological disease activity surrogate markers. This approach may be of clinical importance in measuring both global disease activity and treatment response in patients with CD.