Diagnostics

Background/Objectives: Photon-counting computed tomography (PCCT) enables substantial radiation dose reduction while preserving high spatial resolution. Its potential for image-guided navigation in endoscopic sinus surgery (ESS), particularly at ultra-low dose levels, remains insufficiently explored. This study aimed to evaluate the feasibility of PCCT for four different surgical navigation systems at progressively reduced radiation doses. Methods: PCCT datasets of the paranasal sinuses were acquired from two cadaveric specimens using a standard protocol followed by stepwise dose reductions down to 5% of the reference dose. The datasets were used for image-guided navigation with four systems (one optical, three electromagnetic). Registration success, navigation accuracy, and user satisfaction (visual analog scale) were assessed at 100% and 5% dose levels using linear mixed-effects models. Results: Registration was successful for all navigation systems at every dose level. Mean navigation accuracy remained stable despite dose reduction (2.22 ± 1.16 mm at 100% vs. 1.93 ± 1.05 mm at 5% radiation dose; p = 0.364). User satisfaction regarding navigation was consistently high (mean 8.8 ± 0.75) and showed no significant differences between dose levels. Conclusions: PCCT enabled image-guided navigation even at ultra-low radiation doses down to 5% of standard exposure, without compromising navigation accuracy in this initial study. These findings highlight the potential of PCCT to substantially reduce radiation burden while maintaining clinical performance. Further in-human studies are needed.

Background and Clinical Significance: Occult malignancy is an easily missed cause of prolonged fever when urinary findings suggest pyelonephritis, and repeated empirical antibiotic courses can delay tissue diagnosis. We report such a case with competing explanations for fever. CasePresentation: A 62-year-old woman had six months of intermittent fever and one month of dysuria and right flank pain despite nine outpatient antimicrobial courses. On admission, her temperature reached 40.1 °C; she had pyuria with a non-diagnostic urine culture, para-aortic lymphadenopathy on computed tomography and negative blood cultures. Fever abated during intravenous flomoxef, recurred on the seventh day, persisted after its withdrawal and subsided by hospital day 16 before cancer-directed therapy. A single naproxen dose produced only transient defervescence. Nodal biopsy revealed metastatic high-grade serous carcinoma of the tubo-ovarian type (surgical–pathological FIGO stage IIIA1; clinical stage IVB on imaging, not histologically confirmed). The cause of fever remained undetermined; tumor-associated fever, a partially treated urinary infection and flomoxef-associated drug fever were possible contributors. Conclusions: When fever persists despite empirical antimicrobials and reassessment finds no convincing bacterial infection, clinicians should consider stopping rather than escalating antibiotics in stable, non-neutropenic patients under close monitoring, consider drug fever and other non-infectious causes, and pursue prompt tissue diagnosis.

Background/Objectives: Vitamins A and D are critical regulators of immune function, and genetic variation in their metabolic pathways may influence vitamin status and immune responses. This study investigated the combined nutrigenetic roles of vitamins A and D and their association with allergy-related phenotypes. Methods: In this retrospective study, 80 individuals were included (40 with allergy-related phenotypes and 40 controls). Genetic polymorphisms in CYP2R1, GC, VDR, and BCMO1 were analyzed. Serum vitamin A and 25(OH)D concentrations were compared between groups, and multivariable analyses were performed to assess the effects of age and sex. Genotype distributions were evaluated using chi-square tests, and co-occurring genetic patterns were explored using the Apriori algorithm (p < 0.05). Results: Both serum vitamin A and 25(OH)D concentrations were significantly lower in the allergy-related phenotypes. Genotype differences were observed for CYP2R1 rs2060793 and BCMO1 rs12934922; however, only CYP2R1 rs2060793 remained significant after FDR correction. Although residual confounding cannot be ruled out, exploratory association rule mining identified co-occurrence patterns involving GC, VDR, and CYP2R1 variants with vitamin D deficiency and BCMO1 variants with vitamin A deficiency. These findings should be considered preliminary and hypothesis-generating rather than evidence of established or causal genetic effects. Conclusions: These preliminary findings indicate potential associations between vitamin status, specific genetic variants, and allergy-related phenotypes. Because of the study’s retrospective design and limited sample size, these genetic observations should be regarded as hypothesis-generating and warrant validation in larger, prospectively characterized cohorts.