Enhanced Bidirectional Connectivity of the Subthalamo-pallidal Pathway in 6-OHDA-mouse Model of Parkinson's Disease Revealed by Probabilistic Tractography of Diffusion-weighted MRI at 9.4T

An important challenge in Parkinson’s disease (PD) based neuroscience and neuroimaging is mapping the neuronal connectivity of the basal ganglia to understand how the disease affects brain circuitry. However, a majority of diffusion tractography studies have shown difficulties in revealing connections between distant anatomic brain regions and visualizing basal ganglia connectome. In this current study, we investigated the differences in basal ganglia connectivity between 6-OHDA induced ex-vivo PD mouse model and normal ex-vivo mouse model by using diffusion tensor imaging tractography from diffusion-weighted images obtained with a high resolution 9.4 T MR scanner. Connectivity pattern of the basal ganglia were compared between five 6-OHDA and five control ex-vivo mouse brains using results of probabilistic tractography generated with PROBTRACKX. When compared with control mouse, 6-OHDA mouse showed significant enhancements to motor territory-related subthalamopallidal and pallido-subthalamic connectivity. Multi-fiber tractography combined with diffusion MRI data has the potential to help recognize the abnormalities found in connectivity of psychiatric and neurologic disease models.

Theranostics Based on Liposome: Looking Back and Forward / 대한핵의학회잡지

Liposome is one of the oldest yet most successful nanomedicine platforms. Doxil®, PEGylated liposome loaded with doxorubicin (DOX), was approved by the FDA in 1995 for the treatment of AIDS-related Kaposi's sarcoma, and it was the first approval for nanomedicine. Since then, liposome-based therapeutics were approved for the treatment of various diseases and many clinical trials are underway. The success of the liposome-based therapeutics was due to following factors: (1) ease of synthesis, (2) biocompatibility, (3) the ability to load both hydrophilic and hydrophobic agents, and (4) long circulation property after application of polyethylene glycol (PEG). Recently, more functionalities are introduced to liposome platform, which are (1) in vivo imaging probes for optical, magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT), (2) pH and temperature-sensitive lipid moiety, and (3) novel agents for photodynamic and photothermal therapies (PDT, PTT). These conventional and newly tested advantages make the liposome to be one of the most promising nanoplatforms for theranostics.

Theranostics Based on Liposome: Looking Back and Forward / 대한핵의학회잡지

Liposome is one of the oldest yet most successful nanomedicine platforms. Doxil®, PEGylated liposome loaded with doxorubicin (DOX), was approved by the FDA in 1995 for the treatment of AIDS-related Kaposi's sarcoma, and it was the first approval for nanomedicine. Since then, liposome-based therapeutics were approved for the treatment of various diseases and many clinical trials are underway. The success of the liposome-based therapeutics was due to following factors: (1) ease of synthesis, (2) biocompatibility, (3) the ability to load both hydrophilic and hydrophobic agents, and (4) long circulation property after application of polyethylene glycol (PEG). Recently, more functionalities are introduced to liposome platform, which are (1) in vivo imaging probes for optical, magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT), (2) pH and temperature-sensitive lipid moiety, and (3) novel agents for photodynamic and photothermal therapies (PDT, PTT). These conventional and newly tested advantages make the liposome to be one of the most promising nanoplatforms for theranostics.

Current Methods to Define Metabolic Tumor Volume in Positron Emission Tomography: Which One is Better? / 대한핵의학회잡지

Numerous methods to segment tumors using ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) have been introduced. Metabolic tumor volume (MTV) refers to the metabolically active volume of the tumor segmented using FDG PET, and has been shown to be useful in predicting patient outcome and in assessing treatment response. Also, tumor segmentation using FDG PET has useful applications in radiotherapy treatment planning. Despite extensive research on MTV showing promising results, MTV is not used in standard clinical practice yet, mainly because there is no consensus on the optimal method to segment tumors in FDG PET images. In this review, we discuss currently available methods to measure MTV using FDG PET, and assess the advantages and disadvantages of the methods.

Current Methods to Define Metabolic Tumor Volume in Positron Emission Tomography: Which One is Better? / 대한핵의학회잡지

Numerous methods to segment tumors using ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) have been introduced. Metabolic tumor volume (MTV) refers to the metabolically active volume of the tumor segmented using FDG PET, and has been shown to be useful in predicting patient outcome and in assessing treatment response. Also, tumor segmentation using FDG PET has useful applications in radiotherapy treatment planning. Despite extensive research on MTV showing promising results, MTV is not used in standard clinical practice yet, mainly because there is no consensus on the optimal method to segment tumors in FDG PET images. In this review, we discuss currently available methods to measure MTV using FDG PET, and assess the advantages and disadvantages of the methods.

Proposed Motor Scoring System in a Porcine Model of Parkinson's Disease induced by Chronic Subcutaneous Injection of MPTP

Destruction of dopaminergic neurons in the substantia nigra pars compacta (SNpc) is a common pathophysiology of Parkinson's disease (PD). Characteristics of PD patients include bradykinesia, muscle rigidity, tremor at rest and disturbances in balance. For about four decades, PD animal models have been produced by toxin-induced or gene-modified techniques. However, in mice, none of the gene-modified models showed all 4 major criteria of PD. Moreover, distinguishing between PD model pigs and normal pigs has not been well established. Therefore, we planned to produce a pig model for PD by chronic subcutaneous administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), neurotoxin. Changes in behavioral patterns of pigs were thoroughly evaluated and a new motor scoring system was established for this porcine model that was based on the Unified Parkinson's Disease Rating Scale (UPDRS) in human PD patients. In summary, this motor scoring system could be helpful to analyze the porcine PD model and to confirm the pathology prior to further examinations, such as positron emission tomography-computed tomography (PET-CT), which is expensive, and invasive immunohistochemistry (IHC) of the brain.

Chronic Osteomyelitis in Sternum Mimicking Bone Metastasis of Lung Cancer Patient / 핵의학분자영상

Primary sternal osteomyelitis without predisposing factors is a rare condition, and it is hardly differentiated from metastatic bone tumor especially in patient with the history of primary malignancy because osteomyelities shares frequently common findings with metastatic bone lesion on 18F-FDG PET and bone scan. Although there have been several publications of primary osteomyelitis mimicking bone metastasis in the spine or extremities, we report a case of primary sternal osteomyelitis in the patient with lung cancer, which has, to our knowledge, not been reported before.