Utility of Thin-slice Fat-suppressed Single-shot T2-weighted MR Imaging with Deep Learning Image Reconstruction as a Protocol for Evaluating the Pancreas.

PURPOSE: To compare the utility of thin-slice fat-suppressed single-shot T2-weighted imaging (T2WI) with deep learning image reconstruction (DLIR) and conventional fast spin-echo T2WI with DLIR for evaluating pancreatic protocol. METHODS: This retrospective study included 42 patients (mean age, 70.2 years) with pancreatic cancer who underwent gadoxetic acid-enhanced MRI. Three fat-suppressed T2WI, including conventional fast-spin echo with 6 mm thickness (FSE 6 mm), single-shot fast-spin echo with 6 mm and 3 mm thickness (SSFSE 6 mm and SSFSE 3 mm), were acquired for each patient. For quantitative analysis, the SNRs of the upper abdominal organs were calculated between images with and without DLIR. The pancreas-to-lesion contrast on DLIR images was also calculated. For qualitative analysis, two abdominal radiologists independently scored the image quality on a 5-point scale in the FSE 6 mm, SSFSE 6 mm, and SSFSE 3 mm with DLIR. RESULTS: The SNRs significantly improved among the three T2-weighted images with DLIR compared to those without DLIR in all patients (P < 0.001). The pancreas-to-lesion contrast of SSFSE 3 mm was higher than those of the FSE 6 mm (P < 0.001) and tended to be higher than SSFSE 6 mm (P = 0.07). SSFSE 3 mm had the highest image qualities regarding pancreas edge sharpness, pancreatic duct clarity, and overall image quality, followed by SSFSE 6 mm and FSE 6 mm (P < 0.0001). CONCLUSION: SSFSE 3 mm with DLIR demonstrated significant improvements in SNRs of the pancreas, pancreas-to-lesion contrast, and image quality more efficiently than did SSFSE 6 mm and FSE 6 mm. Thin-slice fat-suppressed single-shot T2WI with DLIR can be easily implemented for pancreatic MR protocol.

Rim Enhancement on Contrast-Enhanced CT as a Predictor of Prognosis in Patients with Pancreatic Ductal Adenocarcinoma.

This study investigated the utility of imaging features, such as rim enhancement on contrast-enhanced CT (CECT), in predicting the prognosis of pancreatic ductal adenocarcinoma (PDAC). This retrospective study included 158 patients (84 men; mean age, 68 years) with pathologically confirmed PDAC. The following imaging features were evaluated on CECT by two radiologists: tumor size, tumor attenuation, and the presence of rim enhancement. Cox proportional hazards analysis was performed to identify the imaging and clinicopathological features for predicting disease-free survival (DFS) and overall survival (OS). Pathological features were compared with the presence of rim enhancement. Among the 158 patients, 106 (67%) underwent curative surgery (surgery group) and 52 (33%) received conservative treatment (non-surgery group). Rim enhancement was observed more frequently in the non-surgery group than in the surgery group (44% vs. 20%; p < 0.001). Rim enhancement showed significant associations with shorter DFS and OS in the surgery group (hazard ratios (HRs), 3.03 and 2.99; p < 0.001 and p = 0.003, respectively), whereas tumor size showed significant associations with shorter OS (HR per 1 mm increase, 1.08; p < 0.001). PDACs with rim enhancement showed significant associations with higher histological tumor grades (p < 0.001). PDAC with rim enhancement on CECT could predict poorer prognosis and more aggressive tumor grades.

A Case of Life-threatening Rupture of Small Renal Angiomyolipoma with an Unidentified Intratumoral Aneurysm during Follow-up.

We report a case of a life-threatening ruptured renal angiomyolipoma (AML) that did not meet the criteria for prophylactic treatment (tumor >4 cm or intratumoral aneurysm >5 mm) during follow-up. A woman in her 70s was followed up for a 2.5-cm AML with a rich vascular component. An intratumoral aneurysm >5 mm was not identified for 2 years. She complained of a sudden abdominal pain with hypotension, and contrast-enhanced computed tomography revealed a retroperitoneal hematoma with contrast media extravasation from an intratumoral aneurysm. Emergency transcatheter arterial embolization was successfully performed using N-butyl cyanoacrylate glue. Rupture can occur in small AMLs or in AMLs not identified with intratumoral aneurysms during follow-up. AMLs with a rich vascular component at the kidney surface are more likely to rupture.

Association between tumor morphology and efficacy of atezolizumab plus bevacizumab for advanced hepatocellular carcinoma.

AIM: The IMbrave150 trial revealed that atezolizumab plus bevacizumab (AtezoBv) showed a higher objective response rate (ORR) in patients with advanced hepatocellular carcinoma (HCC). Although conversion therapy after AtezoBv has been recently reported, markers predictive of its efficacy, particularly radiological imaging markers, have not yet been identified. The present study focused on tumor morphological appearance on radiological imaging and evaluated whether it could be associated with AtezoBv efficacy. METHODS: Ninety-five intrahepatic lesions in 74 patients who were given AtezoBv for advanced HCC were recruited for evaluation. The lesions were divided into two groups, simple nodular (SN group) and non-simple nodular (non-SN group), based on the gross morphology on pretreatment imaging, and retrospectively evaluated for treatment response and other relevant clinical outcomes. RESULTS: Assessing the size of individual tumors after treatment, waterfall plots showed that tumor shrinkage in the non-SN group including 56 lesions was higher than that in the SN group comprising 39 lesions. The ORR was significantly higher in the non-SN group (39.3% vs. 15.4%, p = 0.012). Additionally, the median time to nodular progression was longer in the non-SN group (21.0 months vs. 8.1 months, p = 0.119) compared to the SN group. Six patients with non-SN lesions underwent sequential local therapy. CONCLUSIONS: Atezolizumab plus bevacizumab may show increased therapeutic efficacy in patients with tumors with a higher potential for aggressive oncological behavior, such as non-SN lesions. Treatment strategies focusing on conversion therapy may be crucial in patients with non-SN lesions.

Uterine diverticulum mimicking endometriotic cyst of the ovary.

Uterine diverticulum is a rare congenital malformation caused by abnormal fusion of the Müllerian ducts. The diagnosis of uterine diverticulum is difficult, and it is often misdiagnosed as a Müllerian duct anomaly, degenerated uterine fibroid, or ovarian cyst. We herein report a case of uterine diverticulum mimicking an ovarian endometriotic cyst. A multiparous woman with a history of normal vaginal delivery underwent magnetic resonance imaging for investigation of lower abdominal pain and fever. A 155-mm cystic lesion was observed on the ventral side of the uterus. The content of the cyst showed high signal intensity on T1- and T2-weighted images with precipitates of low signal intensity on the dorsal side, suggesting an endometriotic cyst of the ovary. Surgical and pathological findings revealed that the cyst was pedunculated from the anterior uterine body and composed of 3 layers: CD10-positive endometrium, a smooth muscle layer, and serosa. A uterine diverticulum was definitively diagnosed.

Evaluation and Prediction of Post-Hepatectomy Liver Failure Using Imaging Techniques: Value of Gadoxetic Acid-Enhanced Magnetic Resonance Imaging.

Despite improvements in operative techniques and perioperative care, post-hepatectomy liver failure (PHLF) remains the most serious cause of morbidity and mortality after surgery, and several risk factors have been identified to predict PHLF. Although volumetric assessment using imaging contributes to surgical simulation by estimating the function of future liver remnants in predicting PHLF, liver function is assumed to be homogeneous throughout the liver. The combination of volumetric and functional analyses may be more useful for an accurate evaluation of liver function and prediction of PHLF than only volumetric analysis. Gadoxetic acid is a hepatocyte-specific magnetic resonance (MR) contrast agent that is taken up by hepatocytes via the OATP1 transporter after intravenous administration. Gadoxetic acid-enhanced MR imaging (MRI) offers information regarding both global and regional functions, leading to a more precise evaluation even in cases with heterogeneous liver function. Various indices, including signal intensity-based methods and MR relaxometry, have been proposed for the estimation of liver function and prediction of PHLF using gadoxetic acid-enhanced MRI. Recent developments in MR techniques, including high-resolution hepatobiliary phase images using deep learning image reconstruction and whole-liver T1 map acquisition, have enabled a more detailed and accurate estimation of liver function in gadoxetic acid-enhanced MRI.

Evaluation of the clinical behavior of unclassified renal cell carcinoma and its imaging findings on computed tomography and magnetic resonance imaging based on World Health Organization (WHO) 2022.

OBJECTIVES: To ascertain the clinical behaviors of unclassified renal cell carcinoma (RCC) and its characteristic imaging findings on CT and MRI. METHODS: Subjects in this retrospective study were 10 patients who had received a histological diagnosis of unclassified RCC based on World Health Organization (WHO) 2022 and who had undergone CT and/or MRI prior to surgery. In terms of clinical behaviors, TNM classification, stage, postoperative recurrence, time to recurrence, and postoperative survival were evaluated. In terms of imaging findings, tumor size, growth pattern, CT density, dynamic contrast-enhancement (DCE) pattern, internal appearance, presence of a pseudocapsule, and signal intensity on MRI were evaluated. We compared clinical behaviors and imaging findings, and investigated associations between them. RESULTS: One patient could not be followed-up due to death from other causes. Postoperative recurrence was observed in 4 patients, all of whom had Stage 3 RCC. In the remaining 5 patients without recurrence, all 5 patients showed Stage 2 or below. On imaging, unclassified RCC tended to be large (58.7 mm) and solid (100%), and heterogeneous interiors (80%), cystic degeneration (80%) and high intensity on diffusion-weighted imaging (DWI) (71.4%) were common. Comparing patients with and without recurrence, the following findings tended to differ between recurrence and recurrence-free groups: tumor size (73.4 ± 33.9 mm vs. 50.2 ± 33.9 mm, P = 0.286), growth pattern (invasive: 100% vs. 0%, expansive: 0% vs. 100%, P = 0.008 each), DCE pattern (progressive enhancement pattern, 66.7% vs. 0%, washout pattern, 0% vs. 66.7%, P = 0.135 each) and presence of a pseudocapsule (25% vs. 80%, P = 0.167). CONCLUSION: The clinical behavior of unclassified RCC varies widely. Although imaging findings are also variable, findings of large, heterogeneous tumors with cystic degeneration and high intensity on DWI were common. Several imaging findings such as large size, invasive growth, progressive enhancement pattern and no pseudocapsule may enable prediction of prognosis in unclassified RCC.

Magnetic resonance imaging-based risk factors of hepatocellular carcinoma after direct-acting antiviral therapy: A multicenter observational study.

AIM: To determine risk factors associated with hepatocellular carcinoma (HCC) development following direct-acting antiviral (DAA) therapy. METHODS: We enrolled patients with chronic hepatitis C who underwent direct-acting antiviral therapy and achieved sustained virologic response at 12 weeks between 2012 and 2018. Subsequently, patients were followed up. The primary endpoint was the development of HCC or the date of the last follow up when the absence of HCC was confirmed. Uni- and multivariate Cox proportional hazards models were used to identify factors contributing to HCC development, including gadoxetic acid-enhanced magnetic resonance imaging findings. The cumulative incidence rates of HCC development were calculated using the Kaplan-Meier method, and differences between groups were assessed using the log-rank test. RESULTS: The final study cohort comprised 482 patients (median age 70.5 years; 242 men). The median follow-up period was 36.8 months. Among 482 patients, 96 developed HCC (19.9%). The 1-, 3-, and 5-year cumulative rates of HCC development were 4.9%, 18.6%, and 30.5%, respectively. Multivariate analysis revealed that age, male sex, history of HCC, and hepatobiliary phase hypointense nodules without arterial phase hyperenhancement were independent risk factors significantly associated with HCC development (p < 0.001-0.04). The highest risk group included patients with both a history of HCC and the presence of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement (the 1- and 3-year cumulative HCC development rates were 14.2% and 62.2%, respectively). CONCLUSION: History of HCC and presence of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement were strong risk factors for HCC development following direct-acting antiviral therapy.

Development of Pericardial Fat Count Images Using a Combination of Three Different Deep-Learning Models: Image Translation Model From Chest Radiograph Image to Projection Image of Three-Dimensional Computed Tomography.

RATIONALE AND OBJECTIVES: Pericardial fat (PF)-the thoracic visceral fat surrounding the heart-promotes the development of coronary artery disease by inducing inflammation of the coronary arteries. To evaluate PF, we generated pericardial fat count images (PFCIs) from chest radiographs (CXRs) using a dedicated deep-learning model. MATERIALS AND METHODS: We reviewed data of 269 consecutive patients who underwent coronary computed tomography (CT). We excluded patients with metal implants, pleural effusion, history of thoracic surgery, or malignancy. Thus, the data of 191 patients were used. We generated PFCIs from the projection of three-dimensional CT images, wherein fat accumulation was represented by a high pixel value. Three different deep-learning models, including CycleGAN were combined in the proposed method to generate PFCIs from CXRs. A single CycleGAN-based model was used to generate PFCIs from CXRs for comparison with the proposed method. To evaluate the image quality of the generated PFCIs, structural similarity index measure (SSIM), mean squared error (MSE), and mean absolute error (MAE) of (i) the PFCI generated using the proposed method and (ii) the PFCI generated using the single model were compared. RESULTS: The mean SSIM, MSE, and MAE were 8.56 × 10-1, 1.28 × 10-2, and 3.57 × 10-2, respectively, for the proposed model, and 7.62 × 10-1, 1.98 × 10-2, and 5.04 × 10-2, respectively, for the single CycleGAN-based model. CONCLUSION: PFCIs generated from CXRs with the proposed model showed better performance than those generated with the single model. The evaluation of PF without CT may be possible using the proposed method.

Comparative study of sub-second temporal resolution 4D-MRI and 4D-CT for target motion assessment in a phantom model.

To develop and investigate the feasibility of sub-second temporal resolution volumetric T1-weighted four-dimensional (4D-) MRI in comparison with 4D-CT for respiratory-correlated motion assessment using an MRI/CT-compatible phantom. Sub-second high temporal resolution (0.5 s) gradient-echo T1-weighted 4D-MRI was developed using a volumetric acquisition scheme with compressed sensing. An MRI/CT-compatible motion phantom (simulated liver tumor) with three sinusoidal movements of amplitudes and two respiratory patterns was introduced and imaged with 4D-MRI and 4D-CT to investigate the geometric accuracy of the target movement. The geometric accuracy, including centroid position, volume, similarity index of dice similarity coefficient (DSC), and Hausdorff distance (HD), was systematically evaluated. Proposed 4D-MRI achieved a similar geometric accuracy compared with 4D-CT regarding the centroid position, volume, and similarity index. The observed position differences of the absolute average centroid were within 0.08 cm in 4D-MRI and 0.03 cm in 4D-CT, less than the 1-pixel resolution for each modality. The observed volume difference in 4D-MRI/4D-CT was within 0.73 cm3 (4.5%)/0.29 cm3 (2.1%) for a large target and 0.06 cm3 (11.3%)/0.04 cm3 (11.6%) for a small target. The observed DSC values for 4D-MRI/4D-CT were at least 0.93/0.95 for the large target and 0.83/0.84 for the small target. The maximum HD values were 0.25 cm/0.31 cm for the large target and 0.21 cm/0.15 cm for the small target. Although 4D-CT potentially exhibit superior numerical accuracy in phantom studies, the proposed high temporal resolution 4D-MRI demonstrates sub-millimetre geometric accuracy comparable to that of 4D-CT. These findings suggest that the 4D-MRI technique is a viable option for characterizing motion and generating phase-dependent internal target volumes within the realm of radiotherapy.

Lenvatinib Mitigates Transarterial Embolization-Induced Polarization of Tumor-Associated Macrophages in a Rat Hepatocellular Carcinoma Model.

PURPOSE: To investigate the effect of transarterial embolization (TAE) on macrophage polarization and the modulatory effect of lenvatinib when used in combination with TAE in a rat hepatocellular carcinoma model. MATERIALS AND METHODS: A N1S1-bearing orthotopic rat model was subjected to TAE and administered 5 mg/kg of lenvatinib. CD8+, CD68+, and CD206+ cells were examined in 4 groups: sham (n = 5), lenvatinib (n = 5), TAE (n = 5), and combination of TAE and lenvatinib (n = 5). Transcriptome analysis was performed to assess gene expression related to macrophage polarization in the sham, TAE, and combination groups. An in vitro coculture experiment with bone marrow-derived macrophages was performed to identify lenvatinib target in macrophage polarization. RESULTS: There were no significant differences in the number of CD8+ and CD68+ cells among the 4 groups. Tumor-associated macrophage positivity for CD206 was significantly higher in the TAE group (58.1 ± 20.9) than in the sham (11.2 ± 14.3; P < .001) and combination (27.1 ± 19.7; P = .003) groups. In the transcriptome analysis, compared with the genes in the sham group, 5 macrophage polarization-related genes, including St6gal1, were upregulated by more than 1.5 fold in the TAE group and downregulated by more than 1.5 fold in the combination group. The coculture experiment showed that lenvatinib did not affect macrophages but affected N1S1 cells, leading to macrophage polarization. CONCLUSIONS: TAE-induced M2 macrophage polarization. Lenvatinib administration with TAE could reprogram macrophage polarization, improving tumor immune microenvironment.

Prognosis prediction of patients with malignant pleural mesothelioma using conditional variational autoencoder on 3D PET images and clinical data.

BACKGROUND: Deep learning (DL) has been widely used for diagnosis and prognosis prediction of numerous frequently occurring diseases. Generally, DL models require large datasets to perform accurate and reliable prognosis prediction and avoid overlearning. However, prognosis prediction of rare diseases is still limited owing to the small number of cases, resulting in small datasets. PURPOSE: This paper proposes a multimodal DL method to predict the prognosis of patients with malignant pleural mesothelioma (MPM) with a small number of 3D positron emission tomography-computed tomography (PET/CT) images and clinical data. METHODS: A 3D convolutional conditional variational autoencoder (3D-CCVAE), which adds a 3D-convolutional layer and conditional VAE to process 3D images, was used for dimensionality reduction of PET images. We developed a two-step model that performs dimensionality reduction using the 3D-CCVAE, which is resistant to overlearning. In the first step, clinical data were input to condition the model and perform dimensionality reduction of PET images, resulting in more efficient dimension reduction. In the second step, a subset of the dimensionally reduced features and clinical data were combined to predict 1-year survival of patients using the random forest classifier. To demonstrate the usefulness of the 3D-CCVAE, we created a model without the conditional mechanism (3D-CVAE), one without the variational mechanism (3D-CCAE), and one without an autoencoder (without AE), and compared their prediction results. We used PET images and clinical data of 520 patients with histologically proven MPM. The data were randomly split in a 2:1 ratio (train : test) and three-fold cross-validation was performed. The models were trained on the training set and evaluated based on the test set results. The area under the receiver operating characteristic curve (AUC) for all models was calculated using their 1-year survival predictions, and the results were compared. RESULTS: We obtained AUC values of 0.76 (95% confidence interval [CI], 0.72-0.80) for the 3D-CCVAE model, 0.72 (95% CI, 0.68-0.77) for the 3D-CVAE model, 0.70 (95% CI, 0.66-0.75) for the 3D-CCAE model, and 0.69 (95% CI 0.65-0.74) for the without AE model. The 3D-CCVAE model performed better than the other models (3D-CVAE, p = 0.039; 3D-CCAE, p = 0.0032; and without AE, p = 0.0011). CONCLUSIONS: This study demonstrates the usefulness of the 3D-CCVAE in multimodal DL models learned using a small number of datasets. Additionally, it shows that dimensionality reduction via AE can be used to learn a DL model without increasing the overlearning risk. Moreover, the VAE mechanism can overcome the uncertainty of the model parameters that commonly occurs for small datasets, thereby eliminating the risk of overlearning. Additionally, more efficient dimensionality reduction of PET images can be performed by providing clinical data as conditions and ignoring clinical data-related features.

Report of the 23rd nationwide follow-up survey of primary liver cancer in Japan (2014-2015).

For the 23rd Nationwide Follow-up Survey of Primary Liver Cancer in Japan, data from 20 889 newly registered patients and 42 274 previously registered follow-up patients were compiled from 516 institutions over a 2-year period from January 1, 2014 to December 31, 2015. Basic statistics compiled for patients newly registered in the 23rd survey were cause of death, past medical history, clinical diagnosis, imaging diagnosis, treatment-related factors, pathological diagnosis, recurrence status, and autopsy findings. Compared with the previous 22nd survey, the population of patients with hepatocellular carcinoma (HCC) was older at the time of clinical diagnosis, had more female patients, had more patients with non-B non-C HCC, had smaller tumor diameter, and was more frequently treated with hepatectomy. Cumulative survival rates were calculated for HCC, intrahepatic cholangiocarcinoma, and combined hepatocellular cholangiocarcinoma (combined HCC and intrahepatic cholangiocarcinoma) by treatment type and background characteristics for patients newly registered between 2004 and 2015 whose final outcome was survival or death. The median overall survival and cumulative survival rates for HCC were calculated by dividing patients by combinations of background factors (number of tumors, tumor diameter, Child-Pugh grade, or albumin-bilirubin grade) and by treatment type (hepatectomy, radiofrequency ablation therapy, transcatheter arterial chemoembolization, hepatic arterial infusion chemotherapy, and systemic therapy). The same values were also calculated according to registration date by dividing patients newly registered between 1978 and 2015 into five time period groups. The data obtained from this nationwide follow-up survey are expected to contribute to advancing clinical research and treatment of primary liver cancer in the world.

Consensus report from the 10th Global Forum for Liver Magnetic Resonance Imaging: developments in HCC management.

The 10th Global Forum for Liver Magnetic Resonance Imaging (MRI) was held as a virtual 2-day meeting in October 2021, attended by delegates from North and South America, Asia, Australia, and Europe. Most delegates were radiologists with experience in liver MRI, with representation also from specialists in liver surgery, oncology, and hepatology. Presentations, discussions, and working groups at the Forum focused on the following themes: • Gadoxetic acid in clinical practice: Eastern and Western perspectives on current uses and challenges in hepatocellular carcinoma (HCC) screening/surveillance, diagnosis, and management • Economics and outcomes of HCC imaging • Radiomics, artificial intelligence (AI) and deep learning (DL) applications of MRI in HCC. These themes are the subject of the current manuscript. A second manuscript discusses multidisciplinary tumor board perspectives: how to approach early-, mid-, and late-stage HCC management from the perspectives of a liver surgeon, interventional radiologist, and oncologist (Taouli et al, 2023). Delegates voted on consensus statements that were developed by working groups on these meeting themes. A consensus was considered to be reached if at least 80% of the voting delegates agreed on the statements. CLINICAL RELEVANCE STATEMENT: This review highlights the clinical applications of gadoxetic acid-enhanced MRI for liver cancer screening and diagnosis, as well as its cost-effectiveness and the applications of radiomics and AI in patients with liver cancer. KEY POINTS: • Interpretation of gadoxetic acid-enhanced MRI differs slightly between Eastern and Western guidelines, reflecting different regional requirements for sensitivity vs specificity. • Emerging data are encouraging for the cost-effectiveness of gadoxetic acid-enhanced MRI in HCC screening and diagnosis, but more studies are required. • Radiomics and artificial intelligence are likely, in the future, to contribute to the detection, staging, assessment of treatment response and prediction of prognosis of HCC-reducing the burden on radiologists and other specialists and supporting timely and targeted treatment for patients.

Consensus report from the 10th global forum for liver magnetic resonance imaging: multidisciplinary team discussion.

The 10th Global Forum for Liver Magnetic Resonance Imaging was held in October 2021. The themes of the presentations and discussions at this Forum are described in detail in the review by Taouli et al (2023). The focus of this second manuscript developed from the Forum is on multidisciplinary tumor board perspectives in hepatocellular carcinoma (HCC) management: how to approach early-, mid-, and late-stage management from the perspectives of a liver surgeon, an interventional radiologist, and an oncologist. The manuscript also includes a panel discussion by multidisciplinary experts on three selected cases that explore challenging aspects of HCC management. CLINICAL RELEVANCE STATEMENT: This review highlights the importance of a multidisciplinary team approach in liver cancer patients and includes the perspectives of a liver surgeon, an interventional radiologist, and an oncologist, including illustrative case studies. KEY POINTS: • A liver surgeon, interventional radiologist, and oncologist presented their perspectives on the treatment of early-, mid-, and late-stage HCC. • Different perspectives on HCC management between specialties emphasize the importance of multidisciplinary tumor boards. • A multidisciplinary faculty discussed challenging aspects of HCC management, as highlighted by three case studies.

A Case of Rectal Dissemination of Gastric Cancer Diagnosed by Simultaneous 18 F-FDG PET/MRI.

ABSTRACT: Metastatic rectal cancer is rare and difficult to differentiate from primary rectal cancer. A 79-year-old man with a rectal mass detected by CT during postoperative follow-up of gastric cancer underwent 18 F-FDG PET/MRI. Fused PET/MRI images revealed a lower FDG uptake within the mass, which appeared to surround the outside of the rectum, than in the rectal wall, suggesting rectal dissemination of gastric cancer. PET/MRI was useful for differentiating between mass and rectal wall uptake, because of the high contrast resolution of MRI and precise image fusion made possible by simultaneous image acquisition.

[18F]FES PET Resolves the Diagnostic Dilemma of COVID-19-Vaccine-Associated Hypermetabolic Lymphadenopathy in ER-Positive Breast Cancer.

Coronavirus disease (COVID-19) vaccination is known to cause a diagnostic dilemma due to false-positive findings on [18F]FDG PET in vaccine-associated hypermetabolic lymphadenopathy. We present two case reports of women with estrogen-receptor (ER)-positive cancer of the breast who were vaccinated for COVID-19 in the deltoid muscle. [18F]FDG positron emission tomography (PET) demonstrated primary breast cancer and multiple axillary lymph nodes with increased [18F]FDG uptake, diagnosed as vaccine-associated [18F]FDG-avid lymph nodes. Subsequent [18F]FES PET revealed single axillary lymph node metastasis in the vaccine-associated [18F]FDG-avid lymph nodes. To the best of our knowledge, this is the first study showing the usefulness of [18F]FES PET in diagnosing axillary lymph node metastasis in COVID-19-vaccinated patients harboring ER-positive breast cancer. Thus, [18F]FES PET has potential applications in the detection of true-positive metastatic lymph nodes in patients with ER-positive breast cancer regardless of the ipsilateral or contralateral side, who have received COVID-19 vaccination.

Rapid Whole-Body FDG PET/MRI in Oncology Patients: Utility of Combining Bayesian Penalised Likelihood PET Reconstruction and Abbreviated MRI.

This study evaluated the diagnostic value of a rapid whole-body fluorodeoxyglucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) approach, combining Bayesian penalised likelihood (BPL) PET with an optimised ß value and abbreviated MRI (abb-MRI). The study compares the diagnostic performance of this approach with the standard PET/MRI that utilises ordered subsets expectation maximisation (OSEM) PET and standard MRI (std-MRI). The optimal ß value was determined by evaluating the noise-equivalent count (NEC) phantom, background variability, contrast recovery, recovery coefficient, and visual scores (VS) for OSEM and BPL with ß100-1000 at 2.5-, 1.5-, and 1.0-min scans, respectively. Clinical evaluations were conducted for NECpatient, NECdensity, liver signal-to-noise ratio (SNR), lesion maximum standardised uptake value, lesion signal-to-background ratio, lesion SNR, and VS in 49 patients. The diagnostic performance of BPL/abb-MRI was retrospectively assessed for lesion detection and differentiation in 156 patients using VS. The optimal ß values were ß600 for a 1.5-min scan and ß700 for a 1.0-min scan. BPL/abb-MRI at these ß values was equivalent to OSEM/std-MRI for a 2.5-min scan. By combining BPL with optimal ß and abb-MRI, rapid whole-body PET/MRI could be achieved in ≤1.5 min per bed position, while maintaining comparable diagnostic performance to standard PET/MRI.

Improved diagnosis of histological capsule in hepatocallular carcinoma by using nonenhancing capsule appearance in addition to enhancing capsule appearance in gadoxetic acid-enhanced MRI.

To assess the value of nonenhancing capsule by adding to enhancing capsule in gadoxetic acid-enhanced MRI (EOB-MRI) in comparison with contrast-enhanced CT (CE-CT) for diagnosing histological capsule in hepatocellular carcinoma (HCC). One-hundred fifty-one patients with HCC who underwent both CE-CT and EOB-MRI were retrospectively reviewed. Liver Imaging-Reporting and Data System (LI-RADS) v2018 imaging features, including enhancing and nonenhancing capsule were evaluated by two readers in CE-CT and EOB-MRI. Frequencies of each imaging feature were compared between CE-CT and EOB-MRI. The area under the receiver operating characteristic (AUC) curve for the diagnosis of histological capsule was compared across the following three imaging criteria: (1) enhancing capsule in CE-CT, (2) enhancing capsule in EOB-MRI, and (3) enhancing/nonenhancing capsule in EOB-MRI. Enhancing capsule in EOB-MRI was significantly less frequently depicted than that in CE-CT (p < 0.001 and = 0.016 for reader 1 and 2). Enhancing/nonenhancing capsule in EOB-MRI achieved a similar frequency of enhancing in CE-CT (p = 0.590 and 0.465 for reader 1 and 2). Adding nonenhancing capsule to enhancing capsule in EOB-MRI significantly increased AUCs (p < 0.001 for both readers) and achieved similar AUCs compared with enhancing capsule in CE-CT (p = 0.470 and 0.666 for reader 1 and 2). Adding nonenhancing capsule to the definition of capsule appearance can improve the diagnosis of capsule in EOB-MRI for the diagnosis of histological capsule in HCC and decrease discordance of capsule appearance between EOB-MRI and CE-CT.

Clinical Practice Guidelines for Hepatocellular Carcinoma: The Japan Society of Hepatology 2021 version (5th JSH-HCC Guidelines).

The fifth version of the Clinical Practice Guidelines for Hepatocellular Carcinoma was revised by the Japan Society of Hepatology, according to the methodology of evidence-based medicine and partly to the Grading of Recommendations Assessment, Development and Evaluation system, which was published in October 2021 in Japanese. In addition to surveillance-diagnostic and treatment algorithms, a new algorithm for systemic therapy has been created, as multiple drugs for hepatocellular carcinoma can be currently selected. Here, new or revised algorithms and evidence on which the recommendations are based are described.