{"doi":"10.1002/jmri.29689","title":"<scp>T<sub>2</sub></scp> Clusters Are More Sensitive Than Mean <scp>T<sub>2</sub></scp> Change to Detect Early and Longitudinal Changes in Anterior Cruciate Ligament Reconstructed and Healthy Knees","abstract":"Background Post‐traumatic osteoarthritis (PTOA) often follows anterior cruciate ligament reconstruction (ACLR), leading to early cartilage degradation. Change in mean T 2 fails to capture subject‐specific spatial–temporal variations, highlighting the need for robust quantitative methods for early PTOA detection and monitoring. Purpose/Hypothesis Develop and apply 3D T 2 cluster analysis to ACLR and healthy knees over 2.5 years. Study Type Longitudinal case–control study. Subjects ACLR and contralateral knees of 15 subjects (9 male/6 female, 37.7 ± 10 years) and right knee of 15 matched controls (9 male/6 female, 37.1 ± 12 years) were scanned at 3 weeks, 3, 9, 18, and 30 months post‐ACLR. Sequence 3 T Quantitative double echo steady state sequence. Assessment “T 2 cluster analysis” was developed, incorporating registration and thresholding methods to identify and quantify elevated T 2 regions (T 2 clusters, T 2 C) in femoral cartilage. Percentage of cartilage covered by T 2 clusters (T 2 C % ), mean cluster size (T 2 C size ), the number of clusters (T 2 C count ), and ΔT 2 Mean (change in mean femoral cartilage T 2 relative to visit 1) were computed for all knees. Statistical Tests A linear mixed model assessed knee, time, and knee‐time interaction effects on each outcome metric ( P &lt; 0.05), with effect sizes ( η p 2 ) describing the sensitivity of these effects to longitudinal changes. Results T 2 C % ( η p 2 = 0.22), T 2 C size , ( η p 2 = 0.14), and T 2 C count ( η p 2 = 0.51) showed significant and systematic difference between knees (ACLR &gt; contralateral &gt; control). T 2 C % ( η p 2 = 0.24), T 2 C size ( η p 2 = 0.17), and T 2 C count ( η p 2 = 0.11) showed significant longitudinal change across all knees. Specifically, ACLR knees exhibited a significant increase in T 2 C % ( η p 2 = 0.21), T 2 C size ( η p 2 = 0.13), and a decrease in T 2 C count ( η p 2 = 0.07) with time. ΔT 2 Mean showed significant difference between knees ( η p 2 = 0.15), increase with time ( η p 2 = 0.04), with no significant knee‐time interaction ( η p 2 = 0.00, P = 0.772 [contralateral], P = 0.482 [control]). Conclusion T 2 C metrics are more sensitive than ΔT 2 Mean for longitudinal monitoring of femoral cartilage post ACLR. Our findings suggest potential merging of T 2 clusters overtime, forming larger areas of cartilage degradation in ACLR knees. Level of Evidence 1 Technical Efficacy Stage 2","journal":"Journal of Magnetic Resonance Imaging","year":2024,"id":478230,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9478,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1037183,"name":"Anthony A. Gatti","orcid":"0000-0001-6717-8979","position":1,"is_corresponding":false},{"id":426373,"name":"Marianne S. 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Hargreaves","orcid":"0000-0003-0982-3508","position":10,"is_corresponding":false},{"id":301558,"name":"Akshay Chaudhari","orcid":"0000-0002-3667-6796","position":11,"is_corresponding":false},{"id":1316707,"name":"Anoosha Pai S","orcid":"0000-0002-3186-9660","position":0,"is_corresponding":true}],"reference_count":39,"raw_metadata":null,"created_at":"2026-07-19T02:06:42.155024Z","pmid":"39740037","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}