[68Ga]Ga-FAPI PET/CT in brain tumors: comparison with [18F]F-FDG PET/CT.

Purpose: To investigate the feasibility of [68Ga]Ga-FAPI PET/CT in brain tumor imaging and to compare it with [18F]F-FDG PET/CT. Methods: 25 patients with MRI-suspected brain tumors were included in the study. They underwent whole body [18F]F-FDG PET/CT and [68Ga]Ga-FAPI PET/CT and brain scans. The target-to-background ratio (TBR) of brain tumors was calculated with the background of surrounding normal brain tissues uptake. The SUVmax and TBR of [18F]F-FDG PET/CT and [68Ga]Ga-FAPI PET/CT were compared. Additionally, the correlation between the uptake of the tracer by lesions with the greatest diameter of the lesion, the breadth of the oedema band, and the enhancement scores of the MRI enhancement scans was analyzed. Result: [68Ga]Ga-FAPI PET/CT was superior to [18F]F-FDG PET/CT for lesion detection, especially for brain metastases. Among gliomas, only high-grade gliomas uptake [68Ga]Ga-FAPI. Compared with [18F]F-FDG PET/CT, [68Ga]Ga-FAPI PET/CT had a lower SUVmax but a significantly better TBR. On [68Ga]Ga-FAPI PET/CT, the TBR may be associated with brain tumor blood-brain barrier disruption. Conclusions: [68Ga]Ga-FAPI PET/CT is a promising imaging tool for the assessment of brain tumors. Lack of physiological uptake of [68Ga]Ga-FAPI in normal brain parenchyma results in high TBR values, leading to better visualization of lesions and contributing to subsequent targeted therapy studies. Advances in knowledge: Clinical utility of [68Ga]Ga-FAPI PET/CT in brain tumors remains unclear, and there aren't many similar studies in the literature. We evaluated the role of [68Ga]Ga-FAPI PET/CT in diagnosing brain tumors.

Influence of Cirrhosis on 68Ga-FAPI PET/CT in Intrahepatic Tumors.

Background Gallium 68 (68Ga)-labeled fibroblast activation protein inhibitor (FAPI) is of great diagnostic value for intrahepatic tumors. However, cirrhosis may lead to increased 68Ga-FAPI uptake in background liver, affecting the diagnostic ability of 68Ga-FAPI. Purpose To assess the effect of cirrhosis on liver parenchyma and intrahepatic tumor uptake of 68Ga-FAPI and to compare the ability of 68Ga-FAPI and fluorine 18 (18F)-labeled fluorodeoxyglucose (FDG) PET/CT to depict intrahepatic tumors in patients with cirrhosis. Materials and Methods In this secondary analysis of a prospective trial, patients who underwent both 68Ga-FAPI and 18F-FDG PET/CT and those who underwent only 68Ga-FAPI PET/CT between August 2020 and May 2022 were considered for inclusion in the cirrhotic or noncirrhotic group, respectively. Patients with cirrhosis were chosen via a comprehensive assessment of imaging and clinical data, and patients without cirrhosis were randomly selected. 68Ga-FAPI and 18F-FDG PET/CT data were measured by two radiologists. Between-groups and within-group data were tested with the Mann-Whitney U test and the Wilcoxon signed-rank test, respectively. Results A total of 39 patients with cirrhosis (median age, 58 years [IQR, 50-68]; 29 male; 24 intrahepatic tumors) and 48 patients without cirrhosis (median age, 59 years [IQR, 51-67]; 30 male; 23 intrahepatic tumors) were evaluated. In patients without intrahepatic tumors, the liver 68Ga-FAPI average standardized uptake value (SUVavg) was higher in the cirrhotic group than in the noncirrhotic group (median SUVavg, 1.42 [IQR, 0.55-2.85] vs 0.45 [IQR, 0.41-0.72]; P = .002). However, no difference was observed in the diagnosis of intrahepatic tumor sensitivity (98% vs 93%, respectively). When compared with 18F-FDG, the sensitivity of 68Ga-FAPI PET/CT in the detection of intrahepatic tumors in patients with cirrhosis (41% vs 98%, respectively) and maximum standardized uptake value of tumors (median SUVmax, 2.60 [IQR, 2.14-4.49] vs 6.68 [IQR, 4.65-10.08]; P < .001) were higher. Conclusion The sensitivity of 68Ga-FAPI in the diagnosis of intrahepatic tumors was not affected by cirrhosis, and diagnostic accuracy of 68Ga-FAPI was higher than that of 18F-FDG in patients with cirrhosis. © RSNA, 2023 Supplemental material is available for this article.

Current development and prospects of deep learning in spine image analysis: a literature review.

Background and Objective: As the spine is pivotal in the support and protection of human bodies, much attention is given to the understanding of spinal diseases. Quick, accurate, and automatic analysis of a spine image greatly enhances the efficiency with which spine conditions can be diagnosed. Deep learning (DL) is a representative artificial intelligence technology that has made encouraging progress in the last 6 years. However, it is still difficult for clinicians and technicians to fully understand this rapidly evolving field due to the diversity of applications, network structures, and evaluation criteria. This study aimed to provide clinicians and technicians with a comprehensive understanding of the development and prospects of DL spine image analysis by reviewing published literature. Methods: A systematic literature search was conducted in the PubMed and Web of Science databases using the keywords "deep learning" and "spine". Date ranges used to conduct the search were from 1 January, 2015 to 20 March, 2021. A total of 79 English articles were reviewed. Key Content and Findings: The DL technology has been applied extensively to the segmentation, detection, diagnosis, and quantitative evaluation of spine images. It uses static or dynamic image information, as well as local or non-local information. The high accuracy of analysis is comparable to that achieved manually by doctors. However, further exploration is needed in terms of data sharing, functional information, and network interpretability. Conclusions: The DL technique is a powerful method for spine image analysis. We believe that, with the joint efforts of researchers and clinicians, intelligent, interpretable, and reliable DL spine analysis methods will be widely applied in clinical practice in the future.

68 Ga-DOTA-FAPI-04 PET/CT Imaging of Tracheal Mucoepidermoid Carcinoma.

ABSTRACT: A 23-year-old woman presented with a dry cough and dyspnea. Contrast-enhanced CT revealed an intratracheal space-occupying lesion with continuous homogeneous enhancement and airway stenosis. The patient then underwent 68 Ga-DOTA-FAPI-04 PET/CT, which showed increased uptake of FAPI-04 by the lesion. Postoperative pathology confirmed the lesion as tracheal mucoepidermoid carcinoma. This case reports a rare site of mucoepidermoid carcinoma and highlights the potential utility of 68 Ga-DOTA-FAPI-04 PET/CT for the diagnosis of tracheal mucoepidermoid carcinoma.

FAPI PET/CT research progress in digestive system tumours.

18F-fluorodeoxyglucose positron emission tomography/computed tomography has been used in clinical practice for many years. This modality is of great value for tumour diagnosis, staging, and efficacy evaluations, but it has many limitations in the diagnosis and treatment of digestive system tumours. Fibroblast activation protein is highly expressed in gastrointestinal tumours. Various isotope-labelled fibroblast activation protein inhibitors are widely used in clinical research. These inhibitors have low background uptake in the brain, liver and oral/pharyngeal mucosa and show good contrast between the tumour and background, which makes up for the lack of fluorodeoxyglucose in the diagnosis of digestive system tumours. It better displays the primary tumours, metastases and regional lymph nodes of digestive system tumours, such as oesophageal cancer, gastric cancer and liver cancer, and also provides a new method for treating these tumours. Based on this background, this article introduces the current research status of fibroblast activation protein inhibitor positron emission tomography/computed tomography in various types of digestive system malignant tumours to provide more valuable information for diagnosing and treating digestive system tumours.

Bone Marrow Metastases From Gastric Adenocarcinoma on 68Ga-FAPI-04 PET/CT.

ABSTRACT: A 37-year-old woman complained of fatigue and dizziness for 4 days. Bone marrow biopsy findings were suggestive of digestive tract-derived metastases. 18F-FDG PET/CT revealed mild FDG avidity in the stomach and bone marrow, whereas 68Ga-FAPI-04 PET/CT showed strong FAPI uptake in the FDG-avid lesions. The patient was diagnosed with bone marrow metastases from gastric cancer by a bone marrow biopsy.

18F-PEG1-Vinyl Sulfone-Labeled Red Blood Cells as Positron Emission Tomography Agent to Image Intra-Abdominal Bleeding.

18F-Labeled blood pool agents (BPAs) have attracted great attention for identifying bleeding sites. However, many BPAs are not sufficiently evaluated partially due to the limitations of labeling methods. In our previous work, we noticed that 18F-PEG1-vinyl sulfone (18F-VS) could efficiently label red blood cells (RBCs) ex vivo and in situ. However, its application as BPA is not fully evaluated. In this study, we systematically explored the feasibility of using 18F-VS-labeled RBCs as a positron emission tomography (PET) BPA for intra-abdominal bleeding diagnosis. In brief, we first optimized the labeling conditions, which lead to an 80% labeling yield of RBCs after incubating with 18F-VS in phosphate-buffered saline (PBS) at 37°C for 20 min. 18F-VS-labeled RBCs were found to be stable in vitro, which could simplify its transportation/storage for in vivo applications. In normal rat PET study, the cardiovascular system could be clearly imaged up to 5 h post injection (p.i.). An intra-abdominal hemorrhage rat model demonstrated that the 18F-VS-labeled RBCs clearly showed the dynamic changes of extravascular radioactivity due to intra-abdominal hemorrhage. Validation in the model of gastrointestinal bleeding clearly demonstrated the great potential of using 18F-VS-labeled RBCs as a BPA, which could be further evaluated in future studies.

177Lu-PSMA-RLT of metastatic castration-resistant prostate cancer: limitations and improvements.

The prevalence of metastatic castration-resistant prostate cancer (mCRPC) is increasing, and its prognosis is often poor. As a highly expressed target in mCRPC, prostate-specific membrane antigen (PSMA) is very attractive for its diagnosis and treatment. When the efficacy of chemical therapy is limited, radioligand therapy (RLT)-based on Lutetium-177 (177Lu)-PSMA has received more research as an emerging treatment. To date, most published related studies have proven this method is effective and safe. However, about 1/3 of mCRPC patients have not benefited from 177Lu-PSMA-RLT. The underlying mechanism of this phenomenon remains unclear. So based on the comprehensive research in recent years, this article proposes the possible reasons, including tumor lesions, PSMA heterogeneity, differences in DNA repair defects, and accelerated repopulation. Combining with the existing experience to give suggestions to improve the treatment efficacy, benefit more mCRPC patients.

A Case of Localized Malignant Peritoneal Mesothelioma Evaluated by 18F-FDG PET/CT.

Localized malignant mesothelioma is rare. The prognosis is generally more favorable for this condition than for diffuse malignant mesothelioma. An elderly woman recently complained of abdominal pain, fever, and weight loss. She had no history of asbestos exposure. Her serum CEA level was elevated. Plain CT revealed a mass under the left diaphragm, with liquefaction and necrosis. A contrast-enhanced scan showed circular enhancement of the mass. A subsequent biopsy of the mass revealed a poorly differentiated carcinoma. PET/CT showed a significant FDG-avid subphrenic mass without any indications of metastasis. Postoperative pathological and immunohistochemical examination confirmed a case of malignant mesothelioma.

Decreased Vision and Headache as the Initial Symptoms of Hepatocellular Carcinoma.

Sphenoid sinus metastasis is extremely rare. Herein, we report a case of occult hepatocellular carcinoma with initial symptoms of decreased vision and headache, which were caused by sphenoid sinus metastasis. A 44-year-old man recently complained of bilateral decreased vision and headache. Head MRI showed a soft tissue mass in the sphenoid sinus. Pathological examination of the resected sphenoid sinus mass indicated metastatic carcinoma. Subsequently, F-FDG PET/CT and immunohistochemical analysis of the sphenoid sinus mass confirmed the hepatic origin of the primary lesion.

[Correlation between the stenosis degree of aorto-iliac artery and superior mesenteric artery in patients with lower extremity atherosclerotic occlusive disease by CT angiography].

OBJECTIVE: To investigate the correlation between the stenosis degree of superior mesenteric artery (SMA) and each artery within the scope of aorto-iliac artery in patients with lower extremity atherosclerotic occlusive disease (LEAOD). METHODS: Images of 70 patients who had undergone the aorta-iliac-femoral arteries CT angiography (CTA) examination and had a definite diagnosis of LEAOD due to intermittent claudication or resting pain admitted to Tianjin Hospital from January to December in 2017 were enrolled. The arteries in the aorta as well as iliac were surface-reconstructed, which were analyzed by advanced vascular analysis (AVA) combined with the original images, including SMA trunk, abdominal aorta (AA), left and right common iliac artery (LCIA, RCIA), left and right internal iliac artery (LIIA, RIIA), left and right external iliac artery (LEIA, REIA). The normal reference plane and the maximal stenosis plane were selected, and the stenosis rate of each artery in the reconstruction range was automatically calculated with software. The patient's imaging data were divided into groups with two methods: (1) according to the degree of SMA stenosis, the patients were divided into group I (stenosis degree ≤70%) and group II (stenosis degree > 70%); (2) LEAOD patients with different gender were respectively divided into three groups: middle-aged group (45-59 years old), pre-elderly group (60-74 years old) and elderly group (75-89 years old). The comparison between the stenosis degree of SMA and each artery within the scope of aorto-iliac artery was analyzed with Pearson simple correlation analysis. RESULTS: The incidence of SMA stenosis in all LEAOD patients was 100%. Correlation analysis showed that there was no correlation between the stenosis degree of SMA and AA, LCIA, RCIA, LIIA, RIIA, LEIA, or REIA in group I (n = 64) and group II (n = 6), respectively (r value was -0.021, 0.023, 0.023, -0.137, 0.182, -0.113, 0.141, respectively, in group I, and it was 0.020, -0.560, 0.010, 0.306, -0.204, -0.381, 0.393, respectively, in group II, all P > 0.05). In 52 male patients, there was no correlation between the stenosis degree of SMA and AA, LCIA, RCIA, LIIA, RIIA, LEIA, or REIA in middle-aged group (n = 16), pre-elderly group (n = 27) and elderly group (n = 9), respectively (r value was -0.032, 0.024, 0.324, 0.146, 0.312, 0.008, 0.344, respectively, in middle-aged group, it was -0.108, -0.116, -0.040, -0.249, -0.082, -0.052, 0.096, respectively, in pre-elderly group, and it was 0.182, 0.311, 0.400, 0.360, 0.688, 0.498, 0.406, respectively, in elderly group, all P > 0.05). In 18 female patients, there was also no correlation between the stenosis degree of SMA and above each artery within the scope of aorto-iliac artery in pre-elderly group (n = 11) and elderly group (n = 6), respectively (the r value was -0.170, 0.040, -0.019, 0.152, 0.508, 0.042, 0.456, respectively, in pre-elderly group, and it was -0.660, 0.008, -0.055, -0.056, -0.213, 0.344, 0.011, respectively, in elderly group, all P > 0.05). The correlation in middle-aged group was not analyzed because there was only 1 patient. CONCLUSIONS: Although the atherosclerotic changes in LEAOD patients can affect SMA and aorto-iliac artery at the same time, there was no correlation between the stenosis degree of SMA and each artery within the scope of aorto-iliac artery which may due to the differences in the histological structure and hemodynamics among different arteries. SMA atherosclerotic stenosis and occlusion is a relatively independent disease process for LEAOD.