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Biomedical subjects

Christiane Kuhl

Publications and source records attributed to Christiane Kuhl.

5 recordsLinked to original sources

Resolution-dependent self-supervised transfer in chest radiograph classification.

BACKGROUND: Self-supervised learning (SSL) has improved visual representation learning, but its value in chest radiography remains uncertain. DINOv3 extends earlier SSL models through Gram-anchored self-distillation and explicit high-resolution adaptation. Whether these changes improve transfer learning for chest radiograph classification has not been established. METHODS: We benchmarked DINOv3 against DINOv2 and supervised ImageNet initialization across seven chest radiograph datasets comprising 816,183 radiographs from pediatric and adult cohorts. ViT-B/16 and ConvNeXt-B were evaluated under full fine-tuning at 224 × 224 and 512 × 512 pixels, with targeted 1024 × 1024 experiments on three cohorts. Additional analyses examined parameter-efficient adaptation, synthetic label corruption, external validation, frozen 7B features, and computational efficiency. The primary outcome was the mean area under the receiver operating characteristic curve across labels. RESULTS: In adult cohorts, DINOv3 did not consistently outperform DINOv2 at 224 × 224 pixels, but became the strongest initialization at 512 × 512 pixels, especially with ConvNeXt-B. Gains were greatest for small focal and boundary-dependent abnormalities, whereas large-structure findings changed little. The pediatric cohort showed no significant benefit from DINOv3, higher resolution, or backbone choice. Scaling to 1024 × 1024 rarely improved performance and markedly increased computational cost. ConvNeXt-B remained superior to ViT-B/16 under both full and parameter-efficient adaptation. External validation preserved the 512 × 512 DINOv3 advantage, whereas synthetic label corruption showed that this benefit should not be interpreted simply as superior noise robustness. Frozen DINOv3-7B features underperformed relative to fully adapted 86 to 89M-parameter backbones. CONCLUSIONS: For adult chest radiograph classification, DINOv3 provides its most reliable benefit at 512 × 512 pixels, particularly with ConvNeXt-B. Fully adapted mid-sized models at 512 × 512 pixels provided the best performance-cost trade-off in our benchmark.

Journal Article↗

MRI of the pelvis at 3 T: very high spatial resolution with sensitivity encoding and flip-angle sweep technique in clinically acceptable scan time.

OBJECTIVE: The higher signal at 3.0-T allows spatial resolution to be increased without loss in image quality. We evaluated a T2-weighted turbo spin-echo sequence with high spatial resolution (3T-HR) to determine whether this provides clinically useful pelvic MRI. MATERIALS AND METHODS: We designed a sequence with high spatial resolution (3T-HR) (0.45x0.46x4 mm) that was combined with parallel imaging and the variable refocusing angle technique (8.06 min). We examined 23 patients with gynecological disorders using 3T-HR and a standard sequence (3T-SP; 4.03 min; equivalent to 1.5 T). Two radiologists analyzed tissue contrast, signal to noise, detail delineation and artifact level. RESULTS: Tissue contrasts and signal to noise were rated equal. Motion artifacts occurred more often with 3T-SP despite the longer scanning time of 3T-HR. The higher spatial resolution provided additional information in four patients. In two patients small myomas were detected, in one patient a lymph node metastasis was apparent, and in one patient 3T-HR excluded tumor invasion. CONCLUSIONS: High spatial resolution pelvic studies with high image quality can be obtained at 3 T in acceptable scan time. The higher spatial resolution that is feasible at 3 T also provides more clinically relevant information.

Adolescent↗

Added cancer yield of MRI in screening the contralateral breast of women recently diagnosed with breast cancer: results from the International Breast Magnetic Resonance Consortium (IBMC) trial.

OBJECTIVE: To estimate the added cancer yield of magnetic resonance imaging (MRI) over mammography in the contralateral breast of patients with a recent diagnosis of breast cancer. METHODS: We conducted a prospective, international study of mammography and MRI in women with a recent diagnosis of unilateral breast cancer. Each subject received a mammogram, clinical breast exam (CBE), and MRI of the unaffected breast within a 90 day time period. Definitive diagnosis of suspicious findings was determined through biopsy and central pathology review. RESULTS: Of the 103 eligible women included in study analyses, MRI detected 4 cancers in the contralateral breast while mammography detected none. MRI resulted in 12% (95% CI, 6%-20%) of women recommended for biopsy and 10% of women undergoing additional biopsy. The added cancer yield of MRI was 4% (95% CI, 1%-10%) and the positive predictive value of an abnormal MRI was 33% (95% CI, 10%-65%). Forty percent (4/10) of the biopsies performed based on the MRI recommendation were positive for malignancy. CONCLUSION: In women with a recent breast cancer diagnosis, approximately 4% will have an otherwise occult invasive breast cancer detected in the opposite breast by MRI alone.

Biopsy↗

GATA1-mediated megakaryocyte differentiation and growth control can be uncoupled and mapped to different domains in GATA1.

The DNA-binding hemopoietic zinc finger transcription factor GATA1 promotes terminal megakaryocyte differentiation and restrains abnormal immature megakaryocyte expansion. How GATA1 coordinates these fundamental processes is unclear. Previous studies of synthetic and naturally occurring mutant GATA1 molecules demonstrate that DNA-binding and interaction with the essential GATA1 cofactor FOG-1 (via the N-terminal finger) are required for gene expression in terminally differentiating megakaryocytes and for platelet production. Moreover, acquired mutations deleting the N-terminal 84 amino acids are specifically detected in megakaryocytic leukemia in human Down syndrome patients. In this study, we have systematically dissected GATA1 domains required for platelet release and control of megakaryocyte growth by ectopically expressing modified GATA1 molecules in primary GATA1-deficient fetal megakaryocyte progenitors. In addition to DNA binding, distinct N-terminal regions, including residues in the first 84 amino acids, promote platelet release and restrict megakaryocyte growth. In contrast, abrogation of GATA1-FOG-1 interaction leads to loss of differentiation, but growth of blocked immature megakaryocytes is controlled. Thus, distinct GATA1 domains regulate terminal megakaryocyte gene expression leading to platelet release and restrain megakaryocyte growth, and these processes can be uncoupled.

Amino Acid Sequence↗

Transcriptional profiling identifies Id2 function in dendritic cell development.

Dendritic cells (DCs) are potent antigen-presenting cells with a pivotal role in antigen-specific immune responses. Here, we found that the helix-loop-helix transcription factor Id2 is up-regulated during DC development in vitro and crucial for the development of distinct DC subsets in vivo. Id2-/- mice lack Langerhans cells (LCs), the cutaneous contingent of DCs, and the splenic CD8alpha+ DC subset is markedly reduced. Mice deficient for transforming growth factor (TGF)-beta also lack LCs, and we demonstrate here that, in DCs, TGF-beta induces Id2 expression. We also show that Id2 represses B cell genes in DCs. These findings reveal a TGF-beta-Id2 signaling pathway in DCs and suggest a mechanism by which Id2 affects the lineage choice of B cell and DC progenitors.

B-Lymphocytes↗