Objective: To localize the distribution of regional nodes in recurrent/advanced breast cancer patients based on 18-fludeoxyglucose (FDG) positron emission tomography/CT (PET/CT) images and validate the coverage of clinical target volumes (CTVs) for regional nodes with current contouring guidelines. Methods: We enrolled 154 recurrent/advanced breast cancer patients with FDG-avid regional nodes who underwent PET/CT between January 2018 and June 2020. Involvement of lymph node regions including axillary lymph node level I-III (ALN-I, ALN-II, ALN-III), Rotter’s nodes (RN), medial supraclavicular (SC-M), lateral supraclavicular (SC-L) and internal mammary nodes (IMN) was recorded respectively. Coverage of the CTVs in different atlases and the locations of out-of-field were evaluated. Results: A total of 348 lymph node regions containing disease were identified, including ALN-I 109, ALN-II 46, ALN-III 36, RN 17, SC-M 68, SC-L 36 and IMN 36. Recurrent ALNs mainly located cranially and ventrally to the axillary vein (AV). Ipsilateral cervical nodes were simultaneously affected in 33/76 SC positive patients. RADCOMP (306/348) and RUIJIN (291/348) guidelines had higher coverage compared with RTOG (205/348) and ESTRO (202/348) guidelines (p < 0.001, respectively). In primary non-metastastic and recurrent patients, major missings located in SC-L (7/7, 17/17) and IMN (7/10, 15/19) for RTOG guideline while SC-L (7/7, 17/17) for ESTRO guideline (p < 0.001, respectively). Among recurrent patients, SC-M (22/31) was another major missing area for ESTRO guideline (p < 0.001). Conclusion: The current guidelines effectively cover most regional nodes in postoperative breast cancer patients. SC-L and IMN were the major missing regions. Recurrent ALNs were most often seen in cranial and ventral to the AV. The CTV of patients with clinically positive SC was recommended to extend up to the hyoid level. The CTVs should be adjusted based on risks of recurrence individually. Advances in knowledge: The difference of regional nodes delineation between current guidelines mainly located in SC and IMN regions. High axilla including subclavicular nodes and the RN above AV for recurrent patients and the region between cricoid and hyoid for positive SC patients should be meticulously contoured.

Objective: To evaluate the diagnostic performance of fluorine 18 fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (¹⁸F-FDG PET/MR) in the preoperative staging of hypopharyngeal cancer (HPC), compare it with conventional enhanced computed tomography (CT) and MR, and further explore the prognostic value of its metabolic and diffusion metrics for HPC. Methods: This retrospective study included 33 patients with pathologically confirmed HPC. All patients underwent preoperative ¹⁸F-FDG PET/MR, CT, and MR examination. The staging performance of the three modalities was evaluated using pathological staging as a reference. Additionally, metabolic indicators and diffusion-related parameters from PET/MR were collected to investigate their impact on larynx preservation and survival. Results: PET/MR demonstrated accuracies of 90.9% and 71.4% in the preoperative T and N staging, respectively, significantly higher than those of CT (54.5%, p = 0.001; 42.9%, p = 0.021) and MR (66.7%, p = 0.016; 42.9%, p = 0.021). On the whole, significant differences emerged in the maximum standard uptake value (SUVmax), metabolic tumor volume (MTV), minimum apparent diffusion coefficient (ADCmin), and mean ADC (ADCmean) and combined ratios across different T stages, while SUVmax, mean SUV (SUVmean), total lesion glycolysis (TLG), and MTV varied significantly across different N stages. The ADCmin and ADCmean showed good predictive capability for larynx preservation, with AUCs of 0.857 and 0.920 (p < 0.05), respectively. In Cox multivariate analysis of overall survival, high-level ADCmean (p = 0.004) and low-level TLG/ADCmean (p = 0.022) were significantly associated with better survival. Conclusion: In HPC, ¹⁸F-FDG PET/MR imaging significantly surpasses CT and MR in preoperative diagnostic staging. Its diffusion-related parameters have substantial prognostic value, with high ADC values associated with larynx preservation. ADCmean and TLG/ADCmean are potential prognostic indicators for HPC.

Background: Bulky disease represents a clinically aggressive subset of diffuse large B‐cell lymphoma (DLBCL) associated with adverse clinical outcomes. The aim of this study was to investigate the influence of oncogenic mutations and tumor microenvironment alterations on bulky disease in DLBCL. Methods: We analyzed a cohort of 939 patients with newly diagnosed DLBCL. Using DNA ( n = 934) and RNA ( n = 524) sequencing, we compared oncogenic mutations and tumor microenvironment (TME) alterations based on tumor diameter, with cutoff values at 5.0 cm and 10.0 cm. Further stratification by mutations in key genes (CD58, STAT6, EBF1) correlated with tumor diameter revealed distinct transcriptomic and immunologic profiles. Subsequent single‐cell RNA sequencing, guided by these mutational signatures, resolved the cellular heterogeneity within the TME. Results: Integrative analysis revealed that tumor diameter correlated with increased incidence of mutations in CD58 , STAT6 , and EBF1 ; adverse genetic subtypes such as EZB‐like MYC ⁺ and TP53 ^Mut ; activation of oncogenic pathways (JAK/STAT, BCR, PI3K, and MYC); and an immunosuppressive tumor microenvironment. Notably, immune checkpoint molecules varied across the bulky stages, with CTLA‐4 , TIGIT , ICOS , and CD28 expression inversely correlated with tumor diameter, while CD70 and 4‐1BBL expression positively correlated. Single‐cell RNA sequencing further revealed mutation‐specific tumor microenvironment insights. CD58 ‐mutated tumor exhibited a profoundly immune‐deserted microenvironment dominated by malignant B cells with minimal immune infiltration, whereas STAT6‐ mutated tumor was associated with increased fibroblasts and CD4 + T cells, particularly regulatory T cells (Treg) and Th1‐like cells; EBF1 ‐mutated tumor was characterized by increased proportions of malignant B cells. Conclusions: Collectively, our findings highlight the biological complexity of bulky disease, identifying candidate molecular targets and providing a biological framework for future therapeutic hypothesis generation in this clinically aggressive subset of DLBCL.

Objectives: Oropharyngeal carcinoma is experiencing an increase in incidence and can easily metastasize to the cervical lymph nodes. Therefore, evaluating the tumor boundary and lymph node metastasis before treatment is critical. Both CT and MR may have limitations in describing the specific boundaries of oropharyngeal tumors. To date, no research has applied PET/MR imaging to patients with only oropharyngeal carcinoma and verified its diagnostic value. The aim of our study was to evaluate the diagnostic value of PET/MR in patients with oropharyngeal carcinoma. We prepared PET/MR for comparison with CT/MR for T and N staging, with the aim of exploring the relationship between the imaging parameters and different biological factors. Methods: This was a retrospective, observational study. In total, 13 patients (11 males and 2 females) with oropharyngeal tumors who underwent FDG PET/MR and enhanced CT/MR from July 2021 to December 2022 were retrospectively analyzed. Cohen’s kappa coefficient and the McNemar test were used to compare the consistencies and diagnostic values of FDG PET/MR and enhanced CT/MR imaging in relation to primary tumors and cervical lymph node metastases. Various specific parameters of FDG PET/MR were included in the statistics. Spearman correlation coefficients were used to analyze the relationship between the parameters and the tumor stage, the degree of differentiation, p16 expression, Ki67 expression, and serological tumor markers. Results: The average age of the patients was 61.54 ± 6.62 years old. Preoperative imaging demonstrated good consistency between FDG PET/MR and enhanced CT and MR for the diagnosis of clinical T stage. A total of seven patients underwent surgery directly. Overall, 231 cervical lymph nodes were dissected. Compared to the postoperative histopathological results, PET/MR was significantly more sensitive than enhanced CT/MR imaging (78.57% vs. 50.00%, p < 0.05; 78.57% vs. 64.29%, p < 0.05, respectively). Also, PET/MR showed more accuracy in diagnosing metastatic lymph nodes, but without significance. Combined with PET/MR-specific parameters, the SUV, TLG, and the MTV were found to be higher in the patients with more advanced stages of cancer and lower in those with p16-positive tumors. In addition, they were found to be positively correlated with the level of serum CEA. Conclusions: This is the first study to evaluate the clinical diagnostic value of PET/MR in patients with oropharyngeal carcinoma. We believe that PET/MR has more advantages in describing tumor boundaries. It is more sensitive or even more accurate for the evaluation of metastatic cervical lymph nodes.

Background: Previous research has shown that cadmium-zinc-telluride (CZT) crystals, as semiconductor detectors, provide higher spatial and energy resolution than thallium-activated sodium iodide [NaI(Tl)] crystals. This study aimed to evaluate the extent to which a full-ring CZT single-photon emission computed tomography/computed tomography (SPECT/CT) system could improve the image quality of ^99mTc-methoxyisobutylisonitrile (^99mTc-MIBI) parathyroid imaging, as well as its potential to enhance diagnostic accuracy and optimize imaging protocols. Methods: Two phantoms were acquired: (I) a uniform phantom to obtain the calibration factor; and (II) a National Electrical Manufacturers Association (NEMA) International Electrotechnical Commission (IEC) phantom containing different-sized spheres to compare the contrast-to-noise ratio (CNR) and recovery coefficients (RCs). A total of 85 patients who were diagnosed with hyperparathyroidism (HPT) were enrolled in this study. Two hours after injecting ^99mTc-MIBI, delay-phase parathyroid scanning was performed sequentially on NaI(Tl) SPECT/CT in 8 minutes and full-ring CZT SPECT/CT in 6 minutes. List-mode data were used to reconstruct 3-minute CZT SPECT/CT images. A 10-mm diameter volume of interest (VOI) was used to delineate the lesion and reference regions. The coefficient of variation (CV) and CNR were calculated to quantitatively compare image quality and lesion contrast. The standardized uptake values (SUVs) of the lesions were calculated from the images acquired using the full-ring CZT SPECT/CT. Clinical and pathology information were collected through standardized pre-procedural medical history inquiry and subsequent patient follow-up. Results: The NaI(Tl) system exhibited a lower CNR than the full-ring CZT system when using the same injected activity and their respective recommended NEMA IEC phantom parameters. For the images acquired with the full-ring CZT system, those reconstructed using block sequential regularized expectation maximization (BSREM) 20i10s exhibited a higher CNR than those reconstructed using OSEM 4i10s. Compared with OSEM 20i10s, although the difference in the CNR was not statistically significant, the spheres appeared visually clearer, which may be attributed to a more uniform background (CV: OSEM 20i10s, 19.9%; BSREM 20i10s, 17.9%). In the clinical patients, all the three imaging conditions, including 8-minute NaI(Tl), 3-minute CZT, and 6-minute CZT imaging, identified the same positive lesions upon visual assessment. In the image quality comparison, the full-ring CZT system with the standard 6-minute imaging sequence demonstrated better performance than the NaI(Tl) system to varying degrees. Specifically, the CV was lower for the CZT system based on the thyroid (P=0.022) and mediastinal blood pool (P<0.001), but not significantly different based on the cervical muscles (P=0.599). Similarly, the CNR was higher for the CZT system when using the thyroid as the reference region (P=0.033) and mediastinal blood pool as the reference region (P=0.001), but not significantly different when using the cervical muscles as the reference region (P=0.223). The CNR values from the 3-minute CZT imaging were comparable to those from the standard 6-minute CZT imaging (thyroid, P=0.956; cervical muscles, P=0.265; mediastinal blood pool, P=0.182). Conclusions: The full-ring CZT SPECT/CT system exhibited a higher CNR than the NaI(Tl) crystal-based system in the delay-phase scan of ^99mTc-MIBI parathyroid imaging when using the thyroid and mediastinal blood pool as references. Additionally, it enables acquisition within a reduced time frame while maintaining comparable diagnostic sensitivity.