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  1. Leong SH, Ong SH
    PLoS One, 2017;12(7):e0180307.
    PMID: 28686634 DOI: 10.1371/journal.pone.0180307
    This paper considers three crucial issues in processing scaled down image, the representation of partial image, similarity measure and domain adaptation. Two Gaussian mixture model based algorithms are proposed to effectively preserve image details and avoids image degradation. Multiple partial images are clustered separately through Gaussian mixture model clustering with a scan and select procedure to enhance the inclusion of small image details. The local image features, represented by maximum likelihood estimates of the mixture components, are classified by using the modified Bayes factor (MBF) as a similarity measure. The detection of novel local features from MBF will suggest domain adaptation, which is changing the number of components of the Gaussian mixture model. The performance of the proposed algorithms are evaluated with simulated data and real images and it is shown to perform much better than existing Gaussian mixture model based algorithms in reproducing images with higher structural similarity index.
  2. Too CW, Fong KY, Hang G, Sato T, Nyam CQ, Leong SH, et al.
    J Vasc Interv Radiol, 2024 May;35(5):780-789.e1.
    PMID: 38355040 DOI: 10.1016/j.jvir.2024.02.006
    PURPOSE: To validate the sensitivity and specificity of a 3-dimensional (3D) convolutional neural network (CNN) artificial intelligence (AI) software for lung lesion detection and to establish concordance between AI-generated needle paths and those used in actual biopsy procedures.

    MATERIALS AND METHODS: This was a retrospective study using computed tomography (CT) scans from 3 hospitals. Inclusion criteria were scans with 1-5 nodules of diameter ≥5 mm; exclusion criteria were poor-quality scans or those with nodules measuring <5mm in diameter. In the lesion detection phase, 2,147 nodules from 219 scans were used to develop and train the deep learning 3D-CNN to detect lesions. The 3D-CNN was validated with 235 scans (354 lesions) for sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) analysis. In the path planning phase, Bayesian optimization was used to propose possible needle trajectories for lesion biopsy while avoiding vital structures. Software-proposed needle trajectories were compared with actual biopsy path trajectories from intraprocedural CT scans in 150 patients, with a match defined as an angular deviation of <5° between the 2 trajectories.

    RESULTS: The model achieved an overall AUC of 97.4% (95% CI, 96.3%-98.2%) for lesion detection, with mean sensitivity of 93.5% and mean specificity of 93.2%. Among the software-proposed needle trajectories, 85.3% were feasible, with 82% matching actual paths and similar performance between supine and prone/oblique patient orientations (P = .311). The mean angular deviation between matching trajectories was 2.30° (SD ± 1.22); the mean path deviation was 2.94 mm (SD ± 1.60).

    CONCLUSIONS: Segmentation, lesion detection, and path planning for CT-guided lung biopsy using an AI-guided software showed promising results. Future integration with automated robotic systems may pave the way toward fully automated biopsy procedures.

  3. Rajagopal R, Leong SH, Jawin V, Foo JC, Ahmad Bahuri NF, Mun KS, et al.
    J Pediatr Hematol Oncol, 2021 Oct 01;43(7):e913-e923.
    PMID: 33633029 DOI: 10.1097/MPH.0000000000002116
    BACKGROUND: A higher incidence of pediatric intracranial germ cell tumors (iGCTs) in Asian countries compared with Western countries has been reported. In Malaysia, the literature regarding pediatric iGCTs have been nonexistent. The aim of this study was to review the management, survival, and long-term outcomes of pediatric iGCTs at a single tertiary center in Malaysia.

    PATIENTS AND METHODS: We retrospectively reviewed data from patients below 18 years of age with iGCTs treated at the University Malaya Medical Center (UMMC) from 1998 to 2017.

    RESULTS: Thirty-four patients were identified, with a median follow-up of 3.54 years. Sixteen (47%) patients had pure germinoma tumors (PGs), and the remaining patients had nongerminomatous germ cell tumors (NGGCTs). The median age was 12 years, with a male:female ratio of 4.7:1. Abnormal vision, headache with vomiting, and diabetes insipidus were the commonest presenting symptoms. Twenty-eight patients received initial surgical interventions, 24 were treated with chemotherapy, and 28 received radiotherapy. Eight patients experienced relapses. The 5- and 10-year event-free survival rates were similar at 61.1%±12.6% and 42.9%±12.1% for PG and NGGCT, respectively. The 5- and 10-year overall survival rates were the same at 75.5%±10.8% and 53.3%±12.3% for PG and NGGCT, respectively. Four patients died of treatment-related toxicity. Most of the survivors experienced good quality of life with satisfactory neurologic status.

    CONCLUSIONS: The survival rate of childhood iGCTs in UMMC was inferior to that reported in developed countries. Late diagnosis, poor adherence to treatment, and treatment-related complications were the contributing factors. Although these results highlight a single institution experience, they most likely reflect similar treatment patterns, outcomes, and challenges in other centers in Malaysia.

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