• Asian Pacific Journal of Cancer Prevention
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• 제15권7호
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• pp.2939-2943
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• 2014

Background: While many studies have shown that hormones can influence background parenchymal enhancement (BPE) in breast magnetic resonance imaging (MRI), only few have directly address the effect of radiotherapy. The purpose of this study was to evaluate the impact of radiotherapy on BPE in breast MRI. Materials and Methods: A retrospective search identified 62 women with unilateral breast cancer who had a breast MRI both before and after radiotherapy following breast-conserving surgery. In our study, we assumed that systemic therapy affected both breasts equivalently. We rated the level of BPE of both breasts using a four-point categorical scale. A change in the level of BPE prior to and after treatment was compared in the diseased and contralateral breasts. Results: All patients received a 4256 to 6480 cGy dose of whole breast radiotherapy over 3-7 weeks. The mean timing of the follow-up study was 6.6 months after completion of radiotherapy. Although the BPE showed a decrease in both breasts after treatment, there was a significant reduction of BPE in the irradiated breast compared with the contralateral breast (1.18 versus 0.98 average reduction in BPE level, p=0.042). Conclusions: Radiotherapy is associated with decrease in BPE with MRI.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.172-178
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• 2021

Purpose: This study aimed to develop a deep learning architecture combining two task models to generate synthetic computed tomography (sCT) images from low-tesla magnetic resonance (MR) images to improve metallic marker visibility. Methods: Twenty-three patients with cervical cancer treated with intracavitary radiotherapy (ICR) were retrospectively enrolled, and images were acquired using both a computed tomography (CT) scanner and a low-tesla MR machine. The CT images were aligned to the corresponding MR images using a deformable registration, and the metallic dummy source markers were delineated using threshold-based segmentation followed by manual modification. The deformed CT (dCT), MR, and segmentation mask pairs were used for training and testing. The sCT generation model has a cascaded three-dimensional (3D) U-Net-based architecture that converts MR images to CT images and segments the metallic marker. The performance of the model was evaluated with intensity-based comparison metrics. Results: The proposed model with segmentation loss outperformed the 3D U-Net in terms of errors between the sCT and dCT. The structural similarity score difference was not significant. Conclusions: Our study shows the two-task-based deep learning models for generating the sCT images using low-tesla MR images for 3D ICR. This approach will be useful to the MR-only workflow in high-dose-rate brachytherapy.

• Journal of Korean Neurosurgical Society
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• 제56권6호
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• pp.504-508
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• 2014

A 59-year-old male patient had 5-month history of gait disturbance and memory impairment. His initial brain computed tomography scan showed $3.5{\times}2.8cm$ sized mass with high density in the pineal region. The tumor was hypointense on T2 weighted magnetic resonance images and hyperintense on T1 weighted magnetic resonance images with heterogenous enhancement of central portion. The tumor was totally removed via the occipital transtentorial approach. Black mass was observed in the operation field, and after surgery, histopathological examination confirmed the diagnosis of malignant melanoma. Whole spine magnetic resonance images and whole body 18-fluoro-deoxyglucose positron emission tomography could not demonstrate the primary site of this melanoma. Scrupulous physical examination of his skin and mucosa was done and dark pigmented lesion on his left leg was found, but additional studies including magnetic resonance images and skin biopsy showed negative finding. As a result, final diagnosis of primary pineal malignant melanoma was made. He underwent treatment with the whole brain radiotherapy and extended local boost irradiation without chemotherapy. His preoperative symptoms were disappeared, and no other specific neurological deficits were founded. His follow-up image studies showed no recurrence or distant metastasis until 26 weeks after surgery. Primary pineal malignant melanomas are extremely rare intracranial tumors, and only 17 cases have been reported since 1899. The most recent case report showed favorable outcome by subtotal tumor resection followed by whole brain and extended local irradiation without chemotherapy. Our case is another result to prove that total tumor resection with radiotherapy can be the current optimal treatment for primary malignant melanoma in the pineal region.

• Korean Journal of Radiology
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• 제19권6호
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• pp.1110-1118
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• 2018

Objective: To perform a meta-analysis to quantitatively assess functional magnetic resonance imaging (MRI) in the diagnosis of locally recurrent prostate cancer. Materials and Methods: A comprehensive search of the PubMed, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews was conducted from January 1, 1995 to December 31, 2016. Diagnostic accuracy was quantitatively pooled for all studies by using hierarchical logistic regression modeling, including bivariate modeling and hierarchical summary receiver operating characteristic (HSROC) curves (AUCs). The Z test was used to determine whether adding functional MRI to T2-weighted imaging (T2WI) results in significantly increased diagnostic sensitivity and specificity. Results: Meta-analysis of 13 studies involving 826 patients who underwent radical prostatectomy showed a pooled sensitivity and specificity of 91%, and the AUC was 0.96. Meta-analysis of 7 studies involving 329 patients who underwent radiotherapy showed a pooled sensitivity of 80% and specificity of 81%, and the AUC was 0.88. Meta-analysis of 11 studies reporting 1669 sextant biopsies from patients who underwent radiotherapy showed a pooled sensitivity of 54% and specificity of 91%, and the AUC was 0.85. Sensitivity after radiotherapy was significantly higher when diffusion-weighted MRI data were combined with T2WI than when only T2WI results were used. This was true when meta-analysis was performed on a per-patient basis (p = 0.027) or per sextant biopsy (p = 0.046). A similar result was found when $^1H$-magnetic resonance spectroscopy ($^1H$-MRS) data were combined with T2WI and sextant biopsy was the unit of analysis (p = 0.036). Conclusion: Functional MRI data may not strengthen the ability of T2WI to detect locally recurrent prostate cancer in patients who have undergone radical prostatectomy. By contrast, diffusion-weight MRI and $^1H$-MRS data may improve the sensitivity of T2WI for patients who have undergone radiotherapy.

• Radiation Oncology Journal
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• 제36권1호
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• pp.11-16
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• 2018

Purpose: To investigate interobserver variation in target volume delineations for prostate cancer salvage radiotherapy using planning computed tomography (CT) versus combined planning CT and magnetic resonance imaging (MRI). Materials and Methods: Ten radiation oncologists independently delineated a target volume on the planning CT scans of five cases with different pathological status after radical prostatectomy. Two weeks later, this was repeated with the addition of planning MRI. The volumes obtained with CT only and combined CT and MRI were compared, and the effect of the addition of planning MRI on interobserver variability was assessed. Results: There were large differences in clinical target volume (CTV) delineated by each observer, regardless of the addition of planning MRI ($9.44-139.27cm^3$ in CT only and $7.77-122.83cm^3$ in CT plus MRI) and no significant differences in the mean and standard deviation of CTV. However, there were decreases in mean volume and standard deviation as a result of using the planning MRI. Conclusion: This study showed substantial interobserver variation in target volume delineation for salvage radiotherapy. The combination of planning MRI with CT tended to decrease the target volume and the variation.

• Journal of Korean Neurosurgical Society
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• 제52권3호
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• pp.246-249
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• 2012

Intracranial extraskeletal myxoid chondrosarcoma is extremely rare, with only seven patients previously reported. We present a case report of a 21-year-old woman admitted for weakness in her right extremities and symptoms of increased intracranial pressure. Magnetic resonance imaging (MRI) revealed hydrocephalus and a well-enhanced large mass around her left thalamus. A left parietal craniotomy and a cortisectomy at the superior parietal lobule were performed. Total surgical resection was also performed, and pathology results confirmed an extraskeletal myxoid chondrosarcoma. Postoperative MRI showed no residual tumor, and the patient underwent radiotherapy. After six months of radiotherapy, the patient's headache and weakness had improved to grade IV. This malignant tumor showed high rates of recurrence in previous reports. We here report another occurrence of this highly malignant and rare tumor in a patient treated using total surgical excision and adjuvant radiotherapy.

• Journal of Korean Neurosurgical Society
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• 제40권2호
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• pp.110-113
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• 2006

Surgery and radiotherapy are mainly used for plasma cell neoplasm which constitutes about $1{\sim}2%$ of human malignancy. The authors carried out Fractionated Stereotactic Radiotherapy[FSRT] on the residual tumor after the subtotal removal of Intracranial plasmacytoma. A huge mass lesion was observed on MRI [magnetic resonance image] in the left anterior and middle cranial fossa of a 63-year-old man with left exophthalmus which lasted for a month, and was suspected as a meningioma with strong contrast enhancement. Extramedullary plasmacytoma was diagnosed on histopathological examination. After the surgery, FSRT was also carried out on the residual tumor which invaded the skull base. One-year follow up after FSRT showed contrast enhancement only in the left sphenoid bone on MRI, which indicated significant decrease in the size of the tumor without any abnormal neurologic deficits. We treated intracranial plasmacytoma which invaded left anterior and middle cranial fossa and surrounded cavernous sinus without cranial nerve deficit through subtotal tumor removal and FSRT.

• Journal of Korean Neurosurgical Society
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• 제47권1호
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• pp.51-54
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• 2010

Surgery has a key role in the treatment of malignant peripheral nerve sheath tumors (MPNSTs), but the resectability of paraspinal MPNSTs is only 20%. Therefore, spinal MPNSTs show frequent recurrence and poor prognosis. Local recurrence is much more common than metastasis for MPNSTs, and surgery still has a key role in the treatment of local recurrence. Therefore, it is important that recurrence must be detected before resectability is lost. However, no evidence-based follow-up protocol has been established for MPNST. The authors performed gross total resection in a 34-year-old woman presented with thoracic MPNST. Adjuvant radiotherapy and chemotherapy were not administered since these adjuvant therapies generally do not improve survival in MPNST and may cause additional neurovascular damage. Instead, the authors monitored the primary site every 3 months using magnetic resonance imaging to detect local recurrence at the earliest opportunity. The tumor recurred locally on two occasions without overt symptoms at 21 and 24 months postoperatively. These recurrences were treated successfully by gross total removal.

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.121-128
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• 2022

Purpose: This study evaluated the quality of plans based on magnetic resonance-guided radiotherapy (MRgRT) tri-Co-60, linac, and conventional linac-based volumetric modulated arc therapy (linac-VMAT) for prostate cancer. Methods: Twenty patients suffering from prostate cancer with intermediate risk who were treated by MAT were selected. Additional treatment plans (primary and boost plans) were generated based on MRgRT-tri-Co-60 and MRgRT-linac. The planning target volume (PTV) of MRgRT-based plans was created by adding a 3 mm margin from the clinical target volume (CTV) due to high soft-tissue contrast and real-time motion imaging. On the other hand, the PTV of conventional linac was generated based on a 1 cm margin from CTV. The targets of primary and boost plans were prostate plus seminal vesicle and prostate only, respectively. All plans were normalized to cover 95% of the target volume by 100% of the prescribed dose. Dosimetric characteristics were evaluated for each of the primary, boost, and sum plans. Results: For target coverage and conformity, the three plans showed similar results. In the sum plans, the average value of V_65Gy of the rectum of MRgRT-linac (2.62%±2.21%) was smaller than those of MRgRT tri-Co-60 (9.04%±3.01%) and linac-VMAT (9.73%±7.14%) (P<0.001). In the case of bladder, the average value of V_65Gy of MRgRT-linac was also smaller. Conclusions: In terms of organs at risk sparing, MRgRT-linac shows the best value while maintaining comparable target coverage among the three plans.

• Radiation Oncology Journal
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• 제35권4호
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• pp.349-358
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• 2017

Purpose: This study aimed to evaluate whether prophylactic extended-field pelvic radiotherapy (EF-PRT) yields better results than standard whole pelvic radiotherapy (WPRT) in patients with pelvic lymph node-positive cervical cancer treated with concurrent chemoradiotherapy (CCRT). Materials and Methods: A total of 126 cases of stage IB-IVA cervical cancer that had pelvic lymph node involvement in magnetic resonance imaging and were treated with CCRT between 2000 and 2016 were reviewed. None of the patients had para-aortic lymph node (PALN) metastases. The patients were classified to two groups, namely, those treated with EF-PRT, including prophylactic para-aortic radiotherapy, and those treated only with WPRT. The median dose to the PALN area in patients treated with EF-PRT was 45 Gy. All patients received concurrent cisplatin-based chemotherapy. Results: Overall, 52 and 74 patients underwent EF-PRT and WPRT, respectively. Patient characteristics and irradiated dose were not significantly different, except the dose to the para-aortic area, between the two groups. The median follow-up period was 75.5 months (range, 5 to 195 months). The 10-year cumulative recurrence rate of PALN for EF-PRT vs. WPRT was 6.9% and 10.1% (p = 0.421), respectively. The 10-year disease-free survival and overall survival for EF-PRT vs. WPRT were 69.7% vs. 66.1% (p = 0.748) and 71.7% vs. 72.3% (p = 0.845), respectively. Acute gastrointestinal complications were significantly higher in EF-PRT (n = 21; 40.4%) than WPRT (n = 26; 35.1%) (p = 0.046). Late toxicities were not significantly different in both groups. Conclusion: In this study, prophylactic radiotherapy for PALN does not have an additional benefit in patients with pelvic lymph node-positive cervical cancer treated with CCRT.