Clinical Nuclear Medicine最新文献

We present a 69-year-old man with a history of renal cell carcinoma who previously underwent nephrectomy. He was referred to our department for 99m Tc-FAPI and 99m Tc-PSMA scans (under an investigational protocol) due to a newly diagnosed rising prostate-specific antigen (PSA) level and a suspected retroperitoneal mass of unknown origin. Notably, the patient had a known history of malignant ascites, and his 99m Tc-FAPI scan demonstrated increased radiotracer uptake within the abdominal cavity.

A 64-year-old man presented with severe anemia (hemoglobin 56 g/L; RBC 2.60×10 12 /L) on a background of hypertension, diabetes, coronary heart disease, and cerebral thrombosis. Contrast-enhanced abdominal CT and initial endoscopy were unremarkable. Initial 99m Tc-RBC SPECT/CT scintigraphy localized active bleeding to the descending colon. However, repeat endoscopy revealed brown stool in the terminal ileum. Subsequent 99m Tc-RBC SPECT/CT scintigraphy identified a small-bowel soft-tissue mass whose position shifted confirmed epithelioid angiosarcoma of the small intestine. This case highlights the utility of 99m Tc-RBC SPECT/CT in diagnosing challenging small intestinal angiosarcoma.

Purpose: Fibroblast activation protein (FAP)-targeted radiopharmaceuticals show promise in cancer imaging, but optimization and development of new radiopharmaceuticals to enhance tumor targeting, prolong retention, and improve diagnostic/therapeutic outcomes are ongoing. This study aims to evaluate the biodistribution, pharmacokinetics, dosimetry, and safety of a novel FAP-targeted probe 68 Ga-FAP-75 in humans, and to preliminarily assess its ability to detect malignant tumors.

Patients and methods: Eight patients with solid tumors underwent positron emission tomography/computed tomography (PET/CT) scans at multiple time points after intravenous injection of 68 Ga-FAP-75 (0.05-0.1 mCi/kg). Regions of interest (ROIs) were drawn on different tissues. Blood and urine samples were collected for analyzing the biodistribution, pharmacokinetics, and radiation dose. The safety of 68 Ga-FAP-75 and its ability to detect malignant tumors were also evaluated.

Results: The biodistribution of 68 Ga-FAP-75 in humans was similar to that of other 68 Ga-labeled FAP-targeted probes, with relatively high physiological uptake in the pancreas and uterus. The probe was mainly excreted through the urinary system, with relatively rapid renal excretion and blood clearance rates. Its blood elimination half-life ( T1/2 ) was 24.66 minutes. The total effective dose of 68 Ga-FAP-75 in humans was 1.17E-02 mSv/MBq. No serious adverse events were observed. 68 Ga-FAP-75 PET/CT clearly detected primary tumors and metastases in all patients. Various lesions showed high 68 Ga-FAP-75 uptake as early as 10 minutes postinjection. The maximum standardized uptake value (SUVmax) and mean standardized uptake value (SUVmean) increased gradually, and stabilized within 60-120 minutes. Both tumor-to-liver ratio (TLR) and tumor-to-blood ratio (TBR) increased continuously, showing a favorable target-to-background ratio.

Conclusions: The novel FAP-targeted probe 68 Ga-FAP-75 exhibits favorable biodistribution, pharmacokinetics, and safety, with good tumor specificity and a favorable tumor-to-background ratio, showing great potential in tumor imaging and radionuclide-targeted therapy.

A 25-year-old woman presented with a known case of low-grade parosteal osteosarcoma of the right leg and underwent distal femur replacement. Preoperative workup was negative for distant metastases. Two years later, regular oncologic surveillance including CT was unremarkable. Two and a half years later, the patient developed symptoms of prosthetic material loosening. Tc-99m methylene diphosphonate whole-body bone scanning and SPECT/CT did not show evidence of loosening, but revealed a pleural sarcoma metastasis, which was confirmed by histopathology. Tc-99m methylene diphosphonate uptake has been observed in the soft tissue and lungs in patients with osteosarcoma, but is rarely observed in clinical practice.

Purpose: To validate the American Joint Committee on Cancer (AJCC) 9th edition M1-stage subdivision for de novo metastatic nasopharyngeal carcinoma (DM-NPC) and explore preliminary evidence for a refined classification using 18F-FDG positron emission tomography/computed tomography (PET/CT)-derived metastatic burden.

Patients and methods: A retrospective cohort of 185 DM-NPC patients diagnosed between 2000 and 2022, who underwent pretreatment 18F-FDG PET/CT, was analyzed. Recursive partitioning analysis (RPA) identified prognostic cutoffs for metastatic lesions. Survival outcomes were compared between AJCC 9th edition M1 subgroups (M1a: ≤3 lesions; M1b: >3 lesions) and a redefined PET-based classification (Rd-M1a: single-organ, ≤4 lesions; Rd-M1b: >5 lesions or multiorgan).

Results: Patients with single-organ metastases and ≤4 lesions showed potentially superior overall survival (OS) (2-y OS: 60.4% vs. 29.0%; 3-y OS: 46.2% vs. 19.6%; P<0.001). Higher metastatic burden (>5 lesions) was independently associated with worse OS (HR: 1.81; 95% CI: 1.24-2.64; P=0.002). The redefined classification suggested better prognostic discrimination than the AJCC 9th edition (C-index: 0.594 vs. 0.562; AUC at 36 mo: 0.649 vs. 0.598). Patients classified as Rd-M1b had a significantly unfavorable OS compared with those in the Rd-M1a group (HR: 2.02, 95% CI: 1.39-2.92; P=0.002).

Conclusions: These preliminary findings suggest that 18F-FDG PET/CT may enhance M1-stage stratification by quantifying metastatic burden and distribution in patients with DM-NPC, potentially offering improved prognostic accuracy. However, as a single-institution retrospective study, external validation is essential to confirm these observations and guide personalized treatment strategies.

A 66-year-old woman with a nodule between the bladder and the vagina underwent both 68 Ga-DOTATATE and 18 F-FDG PET/CT. Neither study showed increased activity in the nodule. Cervical paraganglioma was diagnosed from the pathologic examination.

A 58-year-old woman was referred for right wrist pain, with suspicion of stress fracture of the radial styloid. 99m Tc-HDP bone scintigraphy, using new 3D-ring CZT system, was performed. Blood pool SPECT/CT revealed intense hyperemia along the first extensor compartment of the right wrist, suggesting De Quervain tenosynovitis, while late-phase SPECT/CT showed right thumb arthritis. Ultrasound imaging confirmed De Quervain tenosynovitis. Our case highlights the potential of blood pool SPECT/CT using new 3D-ring CZT system to detect relevant extraosseous findings, especially common tendinopathies such as De Quervain tenosynovitis.

A 13-year-old girl with severe Cushingoid features had ectopic ACTH-dependent Cushing syndrome. 18 F-FDG PET/CT demonstrated diffusely FDG-avid bilateral adrenal hyperplasia, confirming ectopic ACTH stimulation, and detected a presacral mass with mild uptake. 68 Ga-DOTA-NOC PET/MRI revealed intense somatostatin-receptor activity (SUVmax: 56.1), and MRI identified fat and cystic elements, suggesting teratoma. Surgery proved a mature teratoma harboring an ACTH-secreting NET (G1). This rare case demonstrates that in pediatric patients with aggressive-appearing presacral masses and life-threatening hypercortisolism, complementary imaging modalities may be necessary to exclude malignancy while identifying the functional tumor source.

Purpose: Imaging protocols for progressive supranuclear palsy (PSP) are increasingly incorporating different PET modalities-including 18 F-fluorodeoxyglucose ( 18 F-FDG; cerebral glucose metabolism), 18 F-FP-CIT (dopamine transporter [DAT] activity), and 18 F-Florzolotau (tau pathology) PET-to improve diagnostic accuracy. In this cross-sectional study, we characterized tracer-specific imaging patterns and evaluated their interrelationships in patients with PSP to clarify the underlying pathophysiological mechanisms.

Materials and methods: Twenty-eight patients with clinically diagnosed PSP underwent 18 F-FDG, 18 F-FP-CIT, and 18 F-Florzolotau PET imaging. Quantitative voxel-based and region-of-interest analyses were conducted. Standardized uptake value ratios (SUVRs) were calculated and compared with sex-matched controls (n=20 per PET modality).

Results: In patients with PSP compared with controls, 18 F-FDG PET revealed significant glucose hypometabolism in frontal, parietal, cerebellar, and subcortical regions. 18 F-FP-CIT PET demonstrated reduced DAT availability in the striatum and midbrain. Finally, 18 F-Florzolotau PET showed elevated tau deposition in the thalamus, midbrain, pons, and precentral gyrus. An inverse correlation linked midbrain tau burden with local glucose metabolism ( r =-0.39, P =0.04). Frontal hypometabolism correlated strongly with subcortical metabolic deficits ( r =0.61, P <0.001). Only the left putamen showed a moderate negative association between DAT loss and tau accumulation ( r =-0.42, P =0.03).

Conclusions: Patients with PSP exhibit metabolic deficits in cortical-subcortical networks, dopaminergic denervation in striatal-midbrain regions, and tau pathology localized to brainstem and thalamic areas. Tracer-specific SUVRs correlations revealed specific interplay among glucose hypometabolism, DAT deficiency, and tau accumulation.

A 5-year-old boy with right-sided chest pain and fever was diagnosed with pleuropulmonary blastoma, confirmed by thoracoscopic biopsy. Initial imaging showed a large hypermetabolic mass in the right lower lobe. After 2 cycles of chemotherapy, FDG PET/CT demonstrated significant solid component shrinkage and increased cystic airspaces with decreased hypermetabolic activity. After surgery, pathology confirmed type II pleuropulmonary blastoma. Nine months later, recurrent disease was detected on follow-up FDG PET/CT. Patient underwent further tumor resection, followed by radiation and chemotherapy. This case illustrates the evolving FDG PET/CT findings, and recurrence of pleuropulmonary blastoma after treatment.