Seminars in nuclear medicine最新文献

Congenital abnormalities of the kidney and urinary tract are amongst the most common in children, often requiring nuclear medicine imaging for diagnosis and treatment planning. Efforts to harmonise paediatric renal scintigraphy have gained momentum, notably through unified guidelines published by the Society of Nuclear Medicine and Molecular Imaging (SNNMI) and the European Association of Nuclear Medicine (EANM). However, despite these guidelines, significant variation in clinical practice persists. Advances in imaging technology have also influenced protocols, with some institutions now incorporating single photon emission computed tomography (SPECT) studies when performing cortical scintigraphy. To assess the current practices, the International Atomic Energy Agency (IAEA) conducted a global survey, revealing substantial variability and gaps in the performance and interpretation of renal studies within countries and globally. This underscores the urgent need for standardization and quality improvement across institutions. The IAEA is uniquely positioned to support the global nuclear medicine community through targeted educational and capacity building initiatives.

Dynamic renal scintigraphy (DRS) has been in routine practice since late 70's and it shows kidney perfusion, concentration function and allows the evaluation of excretion function. The radiopharmaceuticals used for this procedure are excreted either via glomerular filtration or by tubular extraction. Either way DRS allows the nuclear medicine physician to quantify renal functions. There are many parameters introduced for clinical practice and described in detail in nuclear medicine guidelines. This paper aims to recall and underline the importance of these parameters and use of these parameters in advancing clinical research. Nuclear medicine has been working in close relation with basic research, its close collaboration with radiopharmacy provides development of new radiopharmaceuticals for kidney imaging, in addition, technological and software innovation enables us to perform faster acquisitions with lower doses and enables better resolution images. Still, processing and quantification in renal analysis is complicated for average nuclear medicine physicians. Recent advances in artificial intelligence have the potential to overcome this problem. With the help of such algorithms renal scintigraphies have the potential to enlighten clinical problems.

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.

Fibroblast activation proteins (FAPs) are highly expressed in cancer-associated fibroblasts within the tumor microenvironment. Radiolabeled FAP inhibitors (FAPIs) either with 68Ga and 18F can assess the tumor stroma, thus offering a complementary perspective to other imaging modalities. Herein, we aimed to summarize current evidence on FAPI-based imaging in renal cell carcinoma (RCC) and bladder cancer (BC). Moreover, we addressed some perspectives about the utility of FAPI as a theragnostic agents in these urogenital cancers. Across the studies, emerged that FAP expression correlates with tumor aggressiveness, immune evasion, and poor prognosis in both RCC and BC. Indeed, clinical experiences demonstrate that FAPI PET achieves higher tumor-to-background ratios and improved detection of metastatic lesions, mainly peritoneal carcinomatosis and hepatic metastases, as compared with [¹⁸F]FDG. However, urinary excretion limits primary tumor assessment of FAPI like FDG imaging. Early trials of FAPI-based radioligand therapies, including [¹⁷⁷Lu]FAPI-2286, show promising safety and preliminary efficacy. Based on the current premises, FAPI seems a promising agent for genitourinary oncology, requiring further assessment through prospective studies.

Imaging of renal graft function and pathology, including delayed graft function (DGF), often requires a multimodal approach. The existing literature describes a range of imaging modalities - radiography, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography, and nuclear medicine - some of which are more advanced and more commonly used, particularly non-ionizing modalities and nuclear medicine. These techniques are used pre- and post-transplantation in both donors and recipients to improve success of renal transplantation and monitor graft function and potential postoperative complications. Recently, significant efforts have been directed toward integrating novel artificial intelligence (AI) methodologies to enhance the diagnostic and prognostic performance of imaging, though further studies are needed to strengthen and validate these methods. Given the need to monitor renal function and complications in post-transplant patients, as well as the risks of renal biopsy and the emergence of new imaging options, reviewing the literature and synthesizing evidence from high-quality studies to provide an evidence-based summary of renal graft imaging is essential. Therefore, this narrative review sheds light on recent advancements in radiology in renal transplantation and provides an updated overview of renal graft imaging.

FAP-targeted PET radiotracers have shown considerable promise across multiple malignancies, offering improved tumour detection and characterisation compared with conventional imaging. Nephro-urological diseases pose particular diagnostic challenges, as both standard imaging and currently available PET tracers are limited by nonspecific uptake and high background signal related to renal excretion. Given the prominent role of tumour-associated fibroblasts in several nephro-urological cancers, FAP-targeted PET may help address key limitations of current staging and response assessment in this setting. Moreover, upregulated FAP expression is also observed in a range of benign nephro-urological conditions, underpinning growing interest in FAP-targeted PET beyond oncology. This review summarizes the biology of FAP expression in the nephro-urological tract and synthesizes emerging evidence on oncological and non-oncological applications of FAP-targeted PET, with a focus on refining lesion characterization, guiding personalised management, and identifying novel theranostic opportunities in nephro-urology. Taken together, current evidence suggests that FAP-targeted PET may become a valuable complement to existing imaging strategies in nephro-urology, although its standalone clinical utility remains uncertain and requires confirmation in larger, prospective, disease-specific studies before routine adoption.

Molecular imaging with positron emission tomography (PET) is a powerful tool in the clinical management of bladder cancer, providing functional information that complements conventional anatomical imaging. This review summarizes the current role of PET imaging for bladder cancer care, highlighting the strengths and limitations of FDG, and explores future directions, including emerging non-FDG tracers that target alternative aspects of tumor biology, such as specific receptors, fibroblast activation or Nectin-4 expression, which may improve lesion detectability and better characterize disease leading to more precise treatments. In parallel, we discuss key technological advances, including PET/MRI, integration of quantitative PET with radiomics, and artificial intelligence-driven analysis, all of which hold promises for enhancing diagnostic accuracy, refining risk stratification, and supporting personalized clinical decision-making in bladder cancer management.

Conventional tracers for renography are Tc-99m-MAG3 (mercaptoacetyltriglycine) and Tc-99m-DTPA (diethyltriaminepentaacetic acid). Others are Tc-99m-sestamibi, Ga-68-EDTA (ethylenediaminetetraacetic acid) and FDG (F-18-fluorodeoxyglucose), the last mentioned because it is not recognised by tubular sodium glucose cotransporter 2 and therefore enters urine. Renography is routinely performed under furosemide challenge, administered 15 min before, at the same time as or 20 min after tracer administration. The renogram comprises 3 phases: perfusion, rising and declining phases. Perfusion phase is important for renal transplants but, in general, not for native kidneys. Measurement of renal perfusion is a separate issue. Split function is measured from the relative gradients of the second phases but optimally from Patlak-Rutland graphical analysis. The third phase - whether present or not - informs on urinary drainage from hydronephrotic kidneys with suspected outflow tract obstruction. Features of obstruction are prolonged parenchymal transit time (PTT), progressively rising renogram and impaired function. PTT is prolonged in obstruction because of increased intratubular pressure and increased fluid reabsorption. It is measured by deconvolution analysis using a region over the left ventricle for blood pool. Judgement by eye is, however, preferable, especially if the contralateral kidney is normal for comparison. Another cause of prolonged PTT is tubular injury which allows increased water and solute reabsorption from tubular lumen. Symmetrical rising renograms are typically seen. Tc-99m-MAG3 secretion into tubular lumen is mediated by multidrug resistance (MDR) transporters so the renogram is exposed to the effects of MDR inhibitors such as chemotherapeutics. Ga-68-has great potential as renographic agent, especially in renal transplant management.

PSMA-PET has become a pivotal imaging method for staging and restaging of prostate cancer. Risk stratification of the disease is a crucial for the patients to receive most appropriate treatment, and for the clinicians to follow the patients more precisely. PSMA-PET provides non-invasive biomarkers for the risk assessment of prostate cancer, offering prediction of clinical outcomes. PROMISE criteria have been developed as comprehensive and integrated framework demonstrating association with overall survival. In this review, we aim to provide a brief update of the prognostic value of PSMA-PET for risk assessment in prostate cancer.