Blended-Transfer Learning for Compressed-Sensing Cardiac CINE MRI

Purpose@#To overcome the difficulty in building a large data set with a high-quality in medical imaging, a concept of 'blended-transfer learning' (BTL) using a combination of both source data and target data is proposed for the target task. @*Materials and Methods@#Source and target tasks were defined as training of the source and target networks to reconstruct cardiac CINE images from undersampled data, respectively. In transfer learning (TL), the entire neural network (NN) or some parts of the NN after conducting a source task using an open data set was adopted in the target network as the initial network to improve the learning speed and the performance of the target task. Using BTL, an NN effectively learned the target data while preserving knowledge from the source data to the maximum extent possible. The ratio of the source data to the target data was reduced stepwise from 1 in the initial stage to 0 in the final stage. @*Results@#NN that performed BTL showed an improved performance compared to those that performed TL or standalone learning (SL). Generalization of NN was also better achieved. The learning curve was evaluated using normalized mean square error (NMSE) of reconstructed images for both target data and source data. BTL reduced the learning time by 1.25 to 100 times and provided better image quality. Its NMSE was 3% to 8% lower than with SL. @*Conclusion@#The NN that performed the proposed BTL showed the best performance in terms of learning speed and learning curve. It also showed the highest reconstructed-image quality with the lowest NMSE for the test data set. Thus, BTL is an effective way of learning for NNs in the medical-imaging domain where both quality and quantity of data are always limited.

Blended-Transfer Learning for Compressed-Sensing Cardiac CINE MRI

Purpose@#To overcome the difficulty in building a large data set with a high-quality in medical imaging, a concept of 'blended-transfer learning' (BTL) using a combination of both source data and target data is proposed for the target task. @*Materials and Methods@#Source and target tasks were defined as training of the source and target networks to reconstruct cardiac CINE images from undersampled data, respectively. In transfer learning (TL), the entire neural network (NN) or some parts of the NN after conducting a source task using an open data set was adopted in the target network as the initial network to improve the learning speed and the performance of the target task. Using BTL, an NN effectively learned the target data while preserving knowledge from the source data to the maximum extent possible. The ratio of the source data to the target data was reduced stepwise from 1 in the initial stage to 0 in the final stage. @*Results@#NN that performed BTL showed an improved performance compared to those that performed TL or standalone learning (SL). Generalization of NN was also better achieved. The learning curve was evaluated using normalized mean square error (NMSE) of reconstructed images for both target data and source data. BTL reduced the learning time by 1.25 to 100 times and provided better image quality. Its NMSE was 3% to 8% lower than with SL. @*Conclusion@#The NN that performed the proposed BTL showed the best performance in terms of learning speed and learning curve. It also showed the highest reconstructed-image quality with the lowest NMSE for the test data set. Thus, BTL is an effective way of learning for NNs in the medical-imaging domain where both quality and quantity of data are always limited.

Evaluation of the stress distribution in the external hexagon implant system with different hexagon height by FEM-3D / 대한치과보철학회지

PURPOSE: To analyze the stress distribution of the implant and its supporting structures through 3D finite elements analysis for implants with different hexagon heights and to make the assessment of the mechanical stability and the effect of the elements. MATERIALS AND METHODS: Infinite elements modeling with CAD data was designed. The modeling was done as follows; an external connection type Phi 4.0 mm x11.5 mm Osste(R) USII (Osstem Co., Pusan, Korea) implant system was used, the implant was planted in the mandibular first molar region with appropriate prosthetic restoration, the hexagon (implant fixture's external connection) height of 0.0, 0.7, 1.2, and 1.5 mm were applied. ABAQUS 6.4 (ABAQUS, Inc., Providence, USA) was used to calculate the stress value. The force distribution via color distribution on each experimental group's implant fixture and titanium screw was studied based on the equivalent stress (von Mises stress). The maximum stress level of each element (crown, implant screw, implant fixture, cortical bone and cancellous bone) was compared. RESULTS: The hexagonal height of the implant with external connection had an influence on the stress distribution of the fixture, screw and upper prosthesis and the surrounding supporting bone. As the hexagon height increased, the stress was well distributed and there was a decrease in the maximum stress value. If the height of the hexagon reached over 1.2 mm, there was no significant influence on the stress distribution. CONCLUSION: For implants with external connections, a hexagon is vital for stress distribution. As the height of the hexagon increased, the more effective stress distribution was observed.

Clinicopathologic analysis and prognosis of uterine cervical cancer / 대한산부인과학회지

OBJECTIVE: The object of this retrospective study was to evaluate the clinical characteristics and prognosis of invasive uterine cervical cancer. METHODS: 445 evaluable patients with invasive cancer of the cervix were treated at Kyung Hee Medical Center from March 1984 to March 1998. In this retrospective study, we studied the clinico-pathologic characteristics (age, FIGO stage, histologic type, nodal metastasis, and treatment modalities et al) by the review of medical records. RESULTS: 1. The age distribution among the 445 patients ranged from 27 to 90 years, mostly at 51-60 years, which occupied 26.5%. The mean age was 48.9 years. 2. The frequent number of pregnancies was 3-4 times, which occupied 33.3%. The mean number of pregnancies was 5.3 times. The frequent number of deliveries was 3-4 times, which occupied 41.7%. The mean number of deliveries was 3.2 times. 3. Subdivision of 445 cases of invasive cervical carcinoma were made according to the FIGO clinical staging: Stage Ia 77 cases (17.3%), Stage Ib 156 cases (35.0%), Stage IIa 95 cases (21.3%), and Stage IIb 52 cases (11.7%), Stage III 40 cases (9.0%), and Stage IV 25 cases (5.6%). 4. Histologically, squamous cell carcinoma comprised 91.2%, adenocarcinoma 6.6%, adenosquamous carcinoma 1.7%, and others 0.5%. 5. The types of treatment were as follows; operation 36.2%, operation with chemoradiation 13.8%, operation with radiotherapy 11.4%, operation with chemotherapy 11.0%, radiation 8.8%, chemoradiation 6.9%, and others 12.0%. 6. All the excised pelvic and para-aortic lymph nodes (LN) were histologically examined and the incidence of metastasis by clinical stage showed as follows. In Stage Ib 16.4%, 2.3%, in Stage IIa 24.5%, 3.2%, and in the stage IIb 26.7%, 6.7% respectively. The most frequently involved LN among regional pelvic LN is the obturator LN (32%) followed by the external iliac LN (29%). 7. Based on the 445 cases who were available to follow up 5 years or more after treatment, survival rates were studied and analyzed. 5 year survival rate by stage revealed 96% in stage Ia, 87.3% in stage Ib, 81.3% in stage IIa, 72% in stage IIb, 47% in stage III, and 26.4% in stage IV. CONCLUSION: FIGO stage, involvement of resection margin, and LN involvement had prognostic significance in multivariate analysis (p<0.01). However, tumor size, histologic type, depth of cervical wall invasion, and lymphovascular space invasion did not.

Correlation of the Expression of COX-2 and VEGF in Cervical Squamous Cell Carcinomas / 대한산부인과학회잡지

OBJECTIVE: The purpose of this study was to know the potential of growth, invasion and metastasis of uterine cervical cancer associated with neovascularization and to investigate whether the enhanced COX-2 (Cyclooxygenase-2) and VEGF (Vascular Endothelial Growth Factor) expression is showed through CIS to invasive cervical cancer and to examine that COX-2 and VEGF expressions are associated with prognostically worse pathological variables and had a direct correlation with tumor MVD (microvessel density). METHODS: From January 1999 to December 2001, 45 paraffin-embedded cervical specimens were obtained by surgical resection in the Kyung Hee University Medical Center. The study group included 25 cases in invasive squamous carcinomas, 7 cases in microinvasive carcinoma, 9 cases in carcinoma in situ, 4 cases in the benign uterine diseases. All tissues were subjected to immunohistochemical staining for COX-2, VEGF and microvessel density (MVD), and immunostaining was scored using a four-point scale with (0) indicating no expression, (1) light staining, (2) moderate staining, (3) heavy staining. RESULTS: As the cervical tumorigenesis progressed, there was a significant increase of MVC (microvessel count) and COX-2 expression. There is a significant correlation between COX-2 and VEGF expression (r(s)=0.686, p<0.01) in cervical neoplasms. There was no correlation between COX-2, VEGF expression and clinicopathologic factors in cervical caner. CONCLUSION: These findings provide evidence that the expression of COX-2 and VEGF is involved in the promotion of angiogenesis in cervical neoplasms and plays an important role in early invasion.

Two Dermoid Cysts Developing in An Accessory Ovary and An Eutopic Ovary

Accessory ovary is a rare gynecologic condition, and tumors arising in accessory ovaries are extremely rare. Accessory ovary may result from separation of migrating ovaries during embryogenesis and injuries such as inflammation and operation on normal ovary. Congenital malformations, most frequently malformations of the genitourinary organ, are seen in connection with the accessory ovary. We experienced the first case of two dermoid cysts developing in an accessory ovary located in the left infundibulopelvic ligament and another in the eutopic ovary at the same side concurrently. Here, we present this extremely rare case with a review of the literature.

A Case of Superimposed Tuberculous Peritonitis on Chemical Peritonitis Arising in Ruptured Both Ovarian Cystic Teratoma / 대한산부인과학회잡지

Rupture of teratoma is rare. Ovary cystic teratoma was occurred 95% in benign ovary tumor, but chemical peritonitis arising from ruptured cystic teratoma is a scarce case. Peritoneal tuberculosis is also rare disease nowadays. It causes easily fatigue, abdominal distension, intermittent abdominal pain and ascities insidiously. We have recently experienced a case of chemical peritonits from ruptured both ovary cystic teratoma of ovary with superimposed peritoneal tuberculosis in 44 year-old woman and report our scarce case with a brief review of the literature.