Seminars in nuclear medicine最新文献

[¹⁸F] Fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F] FDG-PET/CT) has traditionally been considered suboptimal for the evaluation of renal tumors due to intense physiological tracer accumulation in the urinary tract. However, incidental detection of renal masses can occur during [¹⁸F] FDG-PET examinations, and recognizing that FDG uptake varies according to tumor type can aid differential diagnosis. In patients with renal failure or those undergoing dialysis, reduced urinary excretion lowers background activity, paradoxically improving the visualization of renal tumors. Recent studies have demonstrated that high-grade and sarcomatoid renal cell carcinomas (RCCs) exhibit intense [¹⁸F] FDG uptake associated with poor prognosis, whereas benign and low-grade lesions show relatively low uptake. Although [¹⁸F] FDG-PET/CT has limited sensitivity for nodal staging, it provides high diagnostic accuracy for distant metastases, including osteolytic bone lesions. During postoperative surveillance and restaging, PET/CT contributes to early detection of recurrence and assists in therapeutic decision-making, particularly in high-risk or dialysis patients. In therapeutic monitoring, changes in metabolic parameters-such as SUV_max, metabolic tumor volume, and total lesion glycolysis-correlate with progression-free and overall survival during tyrosine kinase inhibitor or immune checkpoint inhibitor therapy. These parameters complement Response Evaluation Criteria in Solid Tumors (RECIST) and support metabolic response criteria such as PET Response Criteria in Solid Tumors (PERCIST). Moreover, novel tracers developed to overcome the intrinsic limitations of [¹⁸F] FDG, including [¹¹C] Acetate, [¹⁸F] Fluoromisonidazole, and prostate-specific membrane antigen ligands, have shown promise in differentiating fat-poor angiomyolipoma, evaluating tumor hypoxia, and detecting FDG-negative metastases. This review discusses the current role, limitations, and future perspectives of [¹⁸F] FDG-PET in the management of renal tumors, with particular focus on RCC.

Colorectal cancer (CRC) remains one of the most common and deadly malignancies worldwide. Accurate diagnosis, staging, and treatment monitoring are critical for optimizing patient outcomes. Although ¹⁸F-FDG PET/CT is widely utilized in CRC imaging, its diagnostic accuracy can be limited by variable avidity across histologic subtypes and by physiological bowel uptake. Fibroblast activation protein (FAP)-targeted positron emission tomography (FAPI PET/CT) has recently emerged as a promising molecular imaging modality that visualizes cancer-associated fibroblasts (CAFs) within the tumor microenvironment. Compared with FDG, FAPI PET/CT provides markedly improved tumor-to-background contrast and higher sensitivity in detecting both primary and metastatic CRC lesions. Beyond its diagnosis and staging utility, FAPI PET/CT offers valuable potential for therapy guidance, treatment response assessment, and prognostic evaluation. Integration with theranostic approaches further enables a comprehensive "see-and-treat"paradigm. FAPI PET/CT represents a transformative advance in CRC management, offering high-contrast, noninvasive visualization of tumor-stroma interactions and facilitating personalized treatment strategies. While current evidence remains preliminary and largely based on small-scale studies, ongoing clinical trials and technological innovations are expected to further define and expand its clinical applications in colorectal cancer.

Penile cancer is a rare malignancy in which inguinal lymph node status is the main prognostic factor. Metastatic spread follows a predictable pattern, with nearly all cases initially involving the inguinal nodes. Among clinically node-negative (cN0) patients, up to 20%-25% may harbour occult inguinal metastases. The dynamic sentinel node biopsy (DSNB) technique has been developed over several decades as a minimally invasive method to accurately stage patients with cN0 penile cancer. As noninvasive imaging methods currently lack sufficient accuracy, DSNB remains the gold standard for nodal staging in these patients. This review outlines the DSNB technique, emphasizing its multidisciplinary nature and highlighting local variations in practice between centres, which may partly explain differences in the reported average false-negative rate of approximately 12%-13%. We also discuss management strategies for radio-tracer-silent groins and the intraoperative use of frozen section analysis of sentinel nodes, which may permit same-session radical inguinal lymph node dissection (ILND) when metastases are detected. Emerging innovations, including the use of magnetic nanoparticles as alternatives to radioactive tracers and advances in circulating tumour DNA (ctDNA) analysis, may further refine or eventually replace DSNB. Ongoing multidisciplinary efforts should aim to optimize all aspects of the technique to reduce false-negative rates and procedure-related morbidity. Fewer than 20% of patients with metastatic sentinel nodes have additional metastases after ILND. Refining DSNB to better identify patients who truly benefit from ILND would further be an important step, as current guidelines likely lead to overtreatment in more than 80% of these cases.

Recent years have seen substantial advancements in renal positron emission tomography (PET) imaging. Targets for PET imaging include, but are not limited to, angiotensin receptors, norepinephrine transporters, and sodium-glucose cotransporters. All of those novel radiotracers inherit advantages of F18 radiochemistry, thereby allowing for higher clinical throughput or potentially increased diagnostic accuracy. The potential of such novel F18-labeled agents to yield imaging biomarkers, and their potential role for future renal molecular imaging, will be presented in the following article.