PET-guided attention for prediction of microvascular invasion in preoperative hepatocellular carcinoma on PET/CT

Purpose

To achieve PET/CT-based preoperative prediction of microvascular invasion in hepatocellular carcinoma by combining the advantages of PET and CT.

Methods

This retrospective study included a total of 100 patients from two institutions who underwent PET/CT imaging. The above patients were divided into a training cohort (n = 70) and a validation cohort (n = 30). This study was based on PET/CT images to evaluate the possibility of microvascular invasion (MVI) of patients. In this study, we proposed a two-branch PET-guided attention network to predict MVI. The model used a two-branch network to extract image features from PET and CT, respectively. The PET-guided attention module aimed to enable the model to focus on the lesion region and reduce the disturbance of irrelevant and redundant information. Model performance was evaluated by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.

Results

The method outperformed the single-modality prediction model for preoperative hepatocyte microvascular invasion, achieving an AUC of 0.907. On the validation set, accuracy reached 0.846, precision reached 0.881, recall 0.793, and F1-score 0.835.

Conclusion

The model exploits the particularities of the molecular metabolic function of PET and the anatomical structure of CT and can strongly improve the accuracy of clinical diagnosis of MVI.

     

A unique presentation of appendicitis: F-18 FDG PET/CT

A 27-year-old white man was diagnosed with a testicular, metastatic germ cell tumor. The patient was evaluated with F-18 fluorodeoxyglucose positron emission tomography and coregistered computed tomography (FDG PET/CT) as well as a contrast-enhanced CT (CECT) of the abdomen and pelvis. Serologic tests were performed. At laparoscopic appendectomy, findings were consistent with acute suppurative appendicitis. This case exemplifies the relevance of incidental findings detected on FDG PET/CT.     

F-18 FDG PET/CT in relapsing polychondritis

We report a case of relapsing polychondritis for which fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) showed increased FDG accumulation in all rib cartilages, as well as in the larynx, trachea, and major bronchi. Contrast-enhanced CT during PET/CT showed smooth tracheal and bronchial wall thickening with calcification and airway narrowing. After steroid therapy, clinical symptoms and laboratory data were improved and cartilaginous FDG accumulation had completely disappeared. FDG PET/CT is considered to be a powerful radiological tool to assess the disease activity of relapsing polychondritis.     

Collision lung cancer on F-18 FDG PET/CT

We report a case of a primary collision lung cancer consisting of squamous cell carcinoma and adenocarcinoma. A 73-year-old man with an abnormality found on chest radiograph in the right lower lobe was examined by FDG PET/CT (F-18 fluorodeoxyglucose positron emission tomography/computed tomography). The tumor was composed of 2 different morphologic and FDG accumulation portions and a collision tumor was suspected. Histopathologically, this tumor was composed of squamous cell carcinoma and adenocarcinoma. Each element was clearly distinguished but touched. FDG PET/CT is a useful tool to diagnose collision tumor as it shows morphologic and metabolic differences between 2 distinct tumor components.     

Peritoneal Lymphomatosis Imaged by F-18 FDG PET/CT

Peritoneal lymphomatosis is uncommon, but when encountered is associated with aggressive histological subtypes of high-grade lymphoma, such as small-cell, large-cell, mixed large and small cell, non-cleaved, lymphoblastic Burkitt-like, and diffuse large B cell lymphomas. The CT findings of peritoneal lymphomatosis are linear or nodular peritoneal thickening, retroperitoneal lymphadenopathy, omental and mesenteric involvement with streak-like infiltrations or a bulky mass, bowel wall thickening, hepatosplenomegaly, and ascites. The authors report the first FDG PET/CT images of diffuse large B-cell lymphoma of small bowel origin associated with peritoneal lymphomatosis in a 69-year-old man. The lesions demonstrated intense FDG uptake in PET/CT images.     

F-18 FDG PET/CT imaging of low-grade mucoepidermoid carcinoma of the bronchus

Mucoepidermoid carcinomas in the bronchial tree are extremely rare tumors. Such tumors are classified into low-grade and high-grade on the basis of histological criteria. Fluorine-18-fluorodeoxyglucose positron emission tomography (F-18 FDG PET) is a useful technique for the evaluation of pulmonary lesions; however, to our knowledge, F-18 FDG PET findings in mucoepidermoid carcinoma of the bronchus have been described in only a few cases. Identifiable focal F-18 FDG uptake has been reported in high-grade mucoepidermoid carcinoma, but it is unclear whether F-18 FDG accumulates in low-grade mucoepidermoid carcinoma. Here, we present the case of a 37-year-old woman, with pathologically proven low-grade mucoepidermoid carcinoma, who underwent high-resolution computed tomography (CT) and F-18 FDG PET/CT before treatment.     

Palpation thyroiditis seen on F-18 FDG PET/CT

A 29-year-old woman presented with a new right supraclavicular mass on a background of resection of a malignant melanoma from her right shoulder before 4 years. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging revealed uptake in a right supraclavicular node and the inferior pole of the left lobe of the thyroid gland. Subsequent resection and histology of the right supraclavicular node and the left lobe of the thyroid gland demonstrated metastatic melanoma and palpation thyroiditis, respectively. A number of malignant and benign pathologies of the thyroid demonstrate FDG uptake, with 75% being benign. To our knowledge, the findings of palpation thyroiditis on FDG PET/CT have never been previously described.     

Uterine Epithelioid Angiosarcoma on F-18 FDG PET/CT

Uterine epithelioid angiosarcoma can have conventional imaging characteristics similar to those of other uterine tumors, such as leiomyoma, leiomyosarcomas or hemangioendothelioma. Uterine epithelioid angiosarcoma exhibiting increased fluorine-18 fluorodeoxyglucose (F-18 FDG) activity can be misdiagnosed. A 61-year-old woman who was diagnosed with uterine epithelioid angiosarcoma underwent F-18 FDG positron emission tomography/computed tomography (PET/CT) as a part of the pretreatment work up for surgery. F-18 FDG PET/CT showed an intense F-18 FDG uptake in the uterus in addition to increased F-18 FDG uptake at the paraaortic and aortocaval lymph nodes. To our knowledge, this is the first case report of intense F-18 FDG uptake in uterine epithelioid angiosarcoma in Korea.     

Diagnostic trinity: Graves' disease on F-18 FDG PET

A 31-year-old man underwent a whole-body F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scan for cancer screening. There was no history of diabetes, thyroid disease, or noticeable exercise before imaging. The results demonstrated diffusely increased uptake of F-18 FDG in the thyroid and thymus. In addition, there was symmetrically increased uptake of F-18 FDG in skeletal muscles, especially in the psoas and limb muscles. The concurrent appearance of these characteristics led to a diagnosis of Graves' disease.