Gi-Hwan Choi

Photon activated therapy (PAT) using monochromatic Synchrotron x-rays and iron oxide nanoparticles in a mouse tumor model: feasibility study of PAT for the treatment of superficial malignancy

BackgroundX-rays are known to interact with metallic nanoparticles, producing photoelectric species as radiosensitizing effects, and have been exploited in vivo mainly with gold nanoparticles. The purpose of this study was to investigate the potential of sensitizing effect of iron oxide nanoparticles for photon activated therapy.MethodsX-rays photon activated therapy (PAT) was studied by treating CT26 tumor cells and CT26 tumor-bearing mice loaded with 13-nm diameter FeO NP, and irradiating them at 7.1 keV near the Fe K-edge using synchrotron x-rays radiation. Survival of cells was determined by MTT assay, and tumor regression assay was performed for in vivo model experiment. The results of PAT treated groups were compared with x-rays alone control groups.ResultsA more significant reduction in viability and damage was observed in the FeO NP-treated irradiated cells, compared to the radiation alone group (p < 0.04). Injection of FeO NP (100 mg/kg) 30 min prior to irradiation elevated the tumor concentration of magnetite to 40 μg of Fe/g tissue, with a tumor-to-muscle ratio of 17.4. The group receiving FeO NP and radiation of 10 Gy showed 80% complete tumor regression (CTR) after 15–35 days and relapse-free survival for up to 6 months, compared to the control group, which showed growth retardation, resulting in 80% fatality. The group receiving radiation of 40 Gy showed 100% CTR in all cases irrespective of the presence of FeO NP, but CTR was achieved earlier in the PAT-treated group compared with the radiation alone group.ConclusionsAn iron oxide nanoparticle enhanced therapeutic effect with relatively low tissue concentration of iron and 10 Gy of monochromatic X-rays. Since 7.1 keV X-rays is attenuated very sharply in the tissue, FeO NP-PAT may have promise as a potent treatment option for superficial malignancies in the skin, like chest wall recurrence of breast cancer.

In vivo proton magnetic resonance spectroscopy of human spinal mass lesions.

Objective To observe metabolic differences between spinal tumor and other diseases in human spinal mass lesions, in vivo 1H magnetic resonance spectroscopy (MRS) was attempted to obtain metabolic signals in patients with various spinal mass lesions. Methods 1H nuclear magnetic resonance (NMR) spectra were obtained from 14 patients before surgery using a receive-only surface coil on a 1.5 T clinical magnetic resonance imaging (MRI) unit. MRS findings were compared with the histopathologic results from biopsy. In addition, tumor spectra were compared with the spectra of other benign diseases including disc herniation, which can mimic spinal cord tumor. In vitro 1H-NMR spectra were also collected from perchloric acid extracts of some spinal tumors. Results Typical water resonance line widths were in the 6- to 10-Hz range, but the metabolic signals observed were sufficiently resolved to be assigned from comparison with the 1H spectra of brain tissue. Choline was detected in all tumor spectra (n = 6) except ependymoma, whereas it was absent in other benign diseases including disc herniation (mimicking spinal cord tumors), dermoid cyst, tuberculosis, and non–multiple sclerosis myelitis. Spectral patterns of meningiomas, schwannomas, metastasis from renal cell carcinoma, and ependymomas in the spinal cord were similar to those of central nervous system (CNS) tumors. It was not possible to observe distinctive metabolic differences between benign diseases owing to relatively larger line broadening of some signals compared with that in CNS tissue. Conclusions It appeared that acquisition of in vivo 1H-NMR signals was possible in human spinal mass lesions on a 1.5 T clinical MRI unit. Detection of choline only in the spinal tumors may indicate that there is some potential in using in vivo 1H-MRS to distinguish spinal tumors from disc herniation mimicking spinal cord tumors, non–multiple sclerosis myelitis, and dermoid cysts. On the basis of our NMR findings, however, it was not possible to distinguish between benign diseases.

Discal Cyst of the Lumbar Spine: A Case Report

Discal cysts are a rare cause of lumbar radiculopathy. There are only a few reports of this disease in medical literature. The authors describe the case of a 40-year-old man with a lumbar discal cyst that led to radiculopathy. An intraspinal extradural cystic mass was responsible for low and high signal intensities observed in lumbar lesions on T1 and T2 weighted magnetic resonance images. This cyst was a grossly spherical mass with clear serous fluid, which was connected to an adjacent intervertebral disc. Histopathology of the cystic walls revealed fibrous connective tissues without specific cell linings. Clinical symptoms were promptly relieved after surgical resection. Further research on the pathophysiology and treatment of discal cysts are needed.

Clinical outcome of modified cervical lateral mass screw fixation technique.

Objective The purpose of this study was 1) to analyze clinically-executed cervical lateral mass screw fixation by the Kims technique as suggested in the previous morphometric and cadaveric study and 2) to examine various complications and bicortical purchase that are important for b-one fusion. Methods A retrospective study was done on the charts, operative records, radiographs, and clinical follow up of thirty-nine patients. One hundred and seventy-eight lateral mass screws were analyzed. The spinal nerve injury, violation of the facet joint, vertebral artery injury, and the bicortical purchases were examined at each lateral mass. Results All thirty-nine patients received instrumentations with poly axial screws and rod systems, in which one hundred and seventy-eight screws in total. No vertebral artery injury or nerve root injury were observed. Sixteen facet joint violations were observed (9.0%). Bicortical purchases were achieved on one hundred and fifty-six (87.6%). Bone fusion was achieved in all patients. Conclusion The advantages of the Kims technique are that it is performed by using given anatomical structures and that the complication rate is as low as those of other known techniques. The Kims technique can be performed easily and safely without fluoroscopic assistance for the treatment of many cervical diseases.