Revisiting the role of structural connectivity-based parcellation in thalamic nuclei segmentation: Benchmarking against recent state-of-the-art methods

by Daniel H. Nguyen, Debottama Das, Ali Bilgin, Dianne Patterson, Matthew Hook, Chris Butson, Alberto Cacciola, Vinod Kumar Jangir, Manojkumar Saranathan

Leveraging diffusion tractography, connectivity-based parcellation (CBP) is one of the oldest methods for thalamic nuclei segmentation. The goal of this work was to reassess CBP using higher spatial resolution diffusion MRI data and reconstruction algorithms, and to compare it with recent state-of-the-art methods for thalamic nuclei segmentation. Furthermore, these methods were systematically evaluated against three histological atlases and one functional MRI–based atlas to examine their relative anatomical similarities and differences. High resolution diffusion and T1-weighted MRI data from 67 healthy individuals in the Human Connectome Project Young Adult database were analyzed. CBP was performed using probabilistic tractography with cortical targets derived from combining labels of the Human Connectome Project Multi-Modal Parcellation 1.0 atlas into 8, 11, and 23 regions. Results were compared against three recent methods: orientation distribution function clustering (ODF), track density imaging (TDI), and structural MRI-based segmentation. Group level analyses were conducted in the Montreal Neurological Institute space, and Dice overlap coefficients were calculated using four atlases (three histological, one functional). CBP results using newer data and methods were still remarkably similar to the original CBP parcellation results. Across atlases, a consistent hierarchy was observed: HIPS-THOMAS performed best, followed by TDI, ODF, and CBP (Kendall’s W = 1.00, p = 0.007). Histological atlases showed strong mutual agreement (Pearson r = 0.71–0.85), whereas the Zhang atlas demonstrated lower concordance (Pearson r = 0.51–0.63). Despite methodological advances, CBP remains constrained in its ability to delineate thalamic nuclei with histological accuracy. By contrast, structural and diffusion microstructural approaches provided better nuclear localization. These findings highlight the need for hybrid workflows that integrate structural and diffusion-based information to enable more reliable thalamic segmentation for neuroscience research.

Single catheter strategy for transradial angiography and primary percutaneous coronary intervention enhances procedural efficiency, microvascular outcomes, and cost-effectiveness: Implications for STEMI healthcare in resource-limited settings

by Mohajit Arneja, Swetharajan Gunasekar, Dharaneswari Hari Narayanan, Joshma Joseph, Harilalith Kovvuri, Sharath Shanmugam, Pavitraa Saravana Kumar, Asuwin Anandaram, Vinod Kumar Balakrishnan, Jayanty Venkata Balasubramaniyan, Sadhanandham Shanmugasundaram, Sankaran Ramesh, Nagendra Boopathy Senguttuvan

Background

Faster time to reperfusion can be achieved by minimizing various patient and system-level delays that contribute to total ischemic time. Procedural delays within the catheterization laboratory represent a non-negligible and modifiable component in the chain of reperfusion, but remain unquantified by conventional metrics such as door-to-ballon (D2B) time. Universal catheter approaches have rapidly gained traction as an alternative to the traditional two catheter approach for transradial coronary interventions. However, their utility for both diagnostic angiography and subsequent angioplasty is limited, and the impact of this strategy on reperfusion outcomes has remained unexplored. We utilized a procedural metric termed fluoroscopy-to-device (FluTD) time to quantify the efficiency of a single catheter strategy, and assessed its impact on epicardial and myocardial perfusion.

Methods and results

In this retrospective study, consecutive STEMI patients undergoing transradial primary PCI (pPCI) at a tertiary care center in India between May 2022 to October 2024 were analyzed. Patients were divided into two groups: 51 underwent PCI using a single universal guiding catheter (UGC), and 51 underwent the conventional two-catheter (CTC) approach. The primary outcome of the study was a comparison of the FluTD time between the two procedural strategies. Secondary outcomes included myocardial blush grade (MBG), Thrombolysis in Myocardial Infarction (TIMI) flow grade, total fluoroscopy time, radiation dose, device safety and efficacy, and procedural success.The median FluTD time was significantly shorter in the UGC compared to the CTC group (3 minutes [IQR 3–4] vs. 10 minutes [IQR 8–17], p  Conclusion

A single catheter strategy for both angiography and pPCI in STEMI patients was associated with a significant reduction in FluTD time and improved microvascular perfusion, without compromising device safety or efficacy. In low- and middle-income countries (LMICs), where intra- and extra-procedural delays are often more pronounced, inclusion of the single catheter strategy can optimize catheterization workflows and yield substantial cost-savings.

Platinum and etoposide chemotherapy, durvalumab with thoracic radiotherapy in the first-line treatment of patients with extensive-stage small-cell lung cancer: CHEST-RT (TROG 20.01) Trial - protocol for a phase II study

Background

Trans Tasman Radiation Oncology Group 20.01 CHEST-RT (Chemotherapy and Immunotherapy in Extensive Stage Small cell with Thoracic Radiotherapy) is a single-arm, open-label, prospective, multicentre phase II trial study that aims to establish the safety, feasibility and describe the efficacy of incorporating thoracic radiotherapy (TRT) (concurrent or sequential) to chemotherapy and immunotherapy in patients with extensive-stage small-cell lung cancer.

Methods

A single arm of up to 30 evaluable participants given TRT concurrent or sequentially with chemoimmunotherapy will be enrolled. Participants should commence radiotherapy with cycle 3 or cycle 4 of chemotherapy. Those not suitable for concurrent radiotherapy due to large tumour volumes may receive sequential radiotherapy. Accounting for a 15% non-evaluable rate, up to 35 participants will be enrolled. An independent data and safety monitoring committee will review the data and assess safety and feasibility. Progression to a phase III trial would be considered feasible if ≤20% of participants experienced ≥grade 3 oesophageal toxicity and ≤10% experienced ≥grade 3 pneumonitis. This approach would be considered feasible if there is ≤20% treatment discontinuation of systemic therapy secondary to radiation toxicities and ≥75% of participants have tumour volumes that can be safely treated to a dose of 30 Gy in 10 fractions. The primary outcome of the trial is safety and feasibility, and survival and responses will be assessed as secondary endpoints. A predefined subgroup analysis of toxicity will be performed on group 1 (concurrent TRT) versus group 2 participants (consolidation TRT).

Ethics and dissemination

This study was approved by the Peter MacCallum Human Research Ethics Committee (HREC/73189/PMCC-2021). The protocol, technical and clinical data will be disseminated by conference presentations and publications. Any modifications to the protocol will be formally documented by administrative letters and will be submitted to the approving HREC for review and approval.

Trial registration numbers

Australian New Zealand Clinical Trials Registry (ACTRN12621000586819) and ClinicalTrials.gov identifier (NCT05796089).