Adaptive Image Rescaling for Weakly Contrast-Enhanced Lesions in Dedicated Breast CT:A Phantom Study

Purpose@#Dedicated breast CT is an emerging volumetric X-ray imaging modality for diagnosis that does not require any painful breast compression. To improve the detection rate of weakly enhanced lesions, an adaptive image rescaling (AIR) technique was proposed. @*Materials and Methods@#Two disks containing five identical holes and five holes of different diameters were scanned using 60/100 kVp to obtain single-energy CT (SECT), dual-energy CT (DECT), and AIR images. A piece of pork was also scanned as a subclinical trial. The image quality was evaluated using image contrast and contrast-to-noise ratio (CNR). The difference of imaging performances was confirmed using student’s t test. @*Results@#Total mean image contrast of AIR (0.70) reached 74.5% of that of DECT (0.94) and was higher than that of SECT (0.22) by 318.2%. Total mean CNR of AIR (5.08) was 35.5% of that of SECT (14.30) and was higher than that of DECT (2.28) by 222.8%. A similar trend was observed in the subclinical study. @*Conclusion@#The results demonstrated superior image contrast of AIR over SECT, and its higher overall image quality compared to DECT with half the exposure. Therefore, AIR seems to have the potential to improve the detectability of lesions with dedicated breast CT.

Hepatopulmonary Syndrome with Finger Clubbing / 대한내과학회지

Hepatopulmonary syndrome is a rare lung complication of liver cirrhosis, caused by pulmonary microvascular vasodilation that induces abnormal arterial oxygenation. Typical findings on physical examination are finger clubbing and cyanosis. Dyspnea is a common symptom and is worse in the upright position. Contrast echocardiography is a useful diagnostic test. Currently, the only effective treatment is liver transplantation. We report the case of a woman with cirrhosis who has hepatopulmonary syndrome with finger clubbing, confirmed by contrast echocardiography. The patient is waiting for a liver transplant.

Hepatopulmonary Syndrome with Finger Clubbing / 대한내과학회지

Hepatopulmonary syndrome is a rare lung complication of liver cirrhosis, caused by pulmonary microvascular vasodilation that induces abnormal arterial oxygenation. Typical findings on physical examination are finger clubbing and cyanosis. Dyspnea is a common symptom and is worse in the upright position. Contrast echocardiography is a useful diagnostic test. Currently, the only effective treatment is liver transplantation. We report the case of a woman with cirrhosis who has hepatopulmonary syndrome with finger clubbing, confirmed by contrast echocardiography. The patient is waiting for a liver transplant.

Signal and Noise Analysis of Indirect-Conversion Digital Radiography Detectors Using Linear-systems Transfer Theory / 의학물리

For the use of Indirect-conversion CMOS (complementary metal-oxide-semiconductor) detectors for digital x-ray radiography and their better designs, we have theoretically evaluated the spatial-frequency-dependent detective quantum efficiency (DQE) using the cascaded linear-systems transfer theory. In order to validate the developed model, the DQE was experimentally determined by the measured modulation-transfer function (MTF) and noise-power spectrum, and the estimated incident x-ray fluence under the mammography beam quality of W/Al. From the comparison between the theoretical and experimental DQEs, the overall tendencies were well agreed. Based on the developed model, we have investigated the DQEs values with respect to various design parameters of the CMOS x-ray detector such as phosphor quantum efficiency, Swank noise, photodiode quantum efficiency and the MTF of various scintillator screens. This theoretical approach is very useful tool for the understanding of the developed imaging systems as well as helpful for the better design or optimization for new development.

Optimizing Imaging Conditions in Digital Tomosynthesis for Image-Guided Radiation Therapy / 의학물리

Cone-beam digital tomosynthesis (CBDT) has greatly been paid attention in the image-guided radiation therapy because of its attractive advantages such as low patient dose and less motion artifact. Image quality of tomograms is, however, dependent on the imaging conditions such as the scan angle (beta(scan)) and the number of projection views. In this paper, we describe the principle of CBDT based on filtered-backprojection technique and investigate the optimization of imaging conditions. As a system performance, we have defined the figure-of-merit with a combination of signal difference-to-noise ratio, artifact spread function and floating-point operations which determine the computational load of image reconstruction procedures. From the measurements of disc phantom, which mimics an impulse signal and thus their analyses, it is concluded that the image quality of tomograms obtained from CBDT is improved as the scan angle is wider than 60 degrees with a larger step scan angle (Delta beta). As a rule of thumb, the system performance is dependent on . If the exact weighting factors could be assigned to each image-quality metric, we would find the better quantitative imaging conditions.

Geometric Calibration of Cone-beam CT System for Image Guided Proton Therapy / 의학물리

According to improved radiation therapy technology such as IMRT and proton therapy, the accuracy of patient alignment system is more emphasized and IGRT is dominated research field in radiation oncology. We proposed to study the feasibility of cone-beam CT system using simple x-ray imaging systems for image guided proton therapy at National Cancer Center. 180 projection views (2,304x3,200, 14 bit with 127 micrometer pixel pitch) for the geometrical calibration phantom and humanoid phantoms (skull, abdomen) were acquired with 2degrees step angle using x-ray imaging system of proton therapy gantry room (360degrees for 1 rotation). The geometrical calibration was performed for misalignments between the x-ray source and the flat-panel detector, such as distances and slanted angle using available algorithm. With the geometrically calibrated projection view, Feldkamp cone-beam algorithm using Ram-Lak filter was implemented for CBCT reconstruction images for skull and abdomen phantom. The distance from x-ray source to the gantry isocenter, the distance from the flat panel to the isocenter were calculated as 1,517.5 mm, 591.12 mm and the rotated angle of flat panel detector around x-ray beam axis was considered as 0.25degrees. It was observed that the blurring artifacts, originated from the rotation of the detector, in the reconstructed toomographs were significantly reduced after the geometrical calibration. The demonstrated CBCT images for the skull and abdomen phantoms are very promising. We performed the geometrical calibration of the large gantry rotation system with simple x-ray imaging devices for CBCT reconstruction. The CBCT system for proton therapy will be used as a main patient alignment system for image guided proton therapy.

Contrast Enhancement for X-ray Images Based on Combined Enhancement of Scaling and Wavelet Coefficients / 의학물리

An applied technique of contrast enhancement for X-ray image is proposed which is based on combined enhancement of scaling and wavelet coefficients in discrete wavelet transform space. Conventional contrast enhancement methods such as contrast limited adaptive histogram equalization (CLAHE), multi-scale image contrast amplification (MUSICA) and gamma correction were applied on scaling coefficients to enhance the contrast of an original. In order to enhance the detail as well as reduce the blurring caused by up scaling of contrast modified scale coefficients from lower resolution, the sigmoid manipulation function was used to manipulate wavelet coefficients. The contrast detail mammography (CDMAM) phantom was imaged and processed to measure the image line profile of results and contrast to noise ratio (CNR) comparatively. The proposed technique produced better results than direct application of various contrast enhancement methods on image itself. The proposed method can enhance contrast, and also suppress the amplification of noise components in a single process. It could be useful for various applications in medical, industrial and graphical images where contrast and detail are of importance.

The Effect of Opening Lamina Terminalis on the Development of Hydrocephalus after Aneurysmal Subarachnoid Hemorrhage

No abstract available.

Anterior Cervical Fusion with the PCB Instrumentation (Cervical Plate Cage System) in Degenerative Cervical Disease

OBJECTIVE: The anterior interbody fusion for cervical spine disorder may not provide adequate immediate stabilization, whereas anterior cervical spine plating has overcome this main disadvantage. Recently, several types of hardware were introduced and the complications related to these were also reported. In case of degenerative cervical spine disorders, the adequate intervertebral disc space height and lordotic curvature are the major factors for preventing recurrence of symptoms. So we used the PCB instrumentation(cervical plate cage system) for these purpose. MATERIAL AND METHOD: From April 1998 to October 1998, 16 patients with degenerative cervical spine disorders who had radiculopathy or myelopathy were underwent anterior cervical spine fusion with the PCB instrumentation(cervical plate cage system). Single level fusion was accomplished in 8 patients and two level fusion in 8. The mean follow-up period was 4 month. RESULT: All patients show some recovery at discharge. There were no hardware problems. The intervertebral disc space height and lordotic curvature were not changed during follow up. CONCLUSION: These finding suggest that PCB instrumentation can be considered to be one of the useful hardwares for anterior cervical spine fusion in degenerative cervical spine disorders.

Prospective Study of Hemifacial Spasm after Microvascular Decompression

In order to observe the change of the clinical results after Microvascular Decompression(MVD), we followed up 261 cases with hemifacial spasm(HFS). The patients were operated between Nov. 1985 and Aug. 1994. The length of observation had been more than 6 months in all cases. The mean age of the patients was 47.0 years old and the mean duration of symptom was 8.2 years. Female constitutes 82.8% of the total an right side was involved in 52.1%. The most common offender was the anterior inferior cerebellar artery (51.0%), and 33% involved multiple vessels. The most common offender was the anterior inferior cerebellar artery (51.0%), and 33% involved multiple vessels. The postoperative complications occurred in 84 cases, 4 of which were permanent. However, there were no mortalities. Among the 226 cases, which were followed up for more than 6 months after the MVD, the final clinical results of 187 cases were excellent, the success rate was 91.7%, and the patients' satisfaction rate was 96.1%. The rate of excellence was 61.1% at POD 7th and 82.7% at final, respectively. The delayed resolution of the HFS during follow-up comprised 37.4% of the completely resolved cases. According to the above results, the clinical status of HFS after MVD continuously changes, therefore follow-up observation after MVD is needed to evaluate the operative results, especially in the delayed resolved cases.

Boerhaave's syndrome: one case report / 대한흉부외과학회지

No abstract available.

Computed tomographic findings of the pancreatitis

Computed body tomography has become useful in the diagnosis of pancreatic disease. It was found to be are liable, often specific, and noninvasive method for detecting pancreatitis and extra-pancreatic extension of the pathology. Of eight hundred and seventy-two cases studied for abdominal pathology with EMI-CT 5005 whole body scanner form Oct. 1977 to August 1980, 21 cases were confirmed to be pancreatitis clinically or operatively. The authors reviewed the CT findings of the above cases and the results were as follows; 1. Among twenty-one cases, the acute pancreatitis was 12 cases and the chronic pancreatitis was 9 cases. The sex ratio as 17 males to females. 2. In acute pancreatitis, diffuse enlargement of pancreas (11/12), focal enlargement (1/12), loss of peripancreatic fat plane (9/12), thickening of anterior of pararenal fascia (6/12), and smooth margin ofpancreas (5/12) were observed. 3. In chronic pancreatitis, parenchymal atrophy (7/9), normal size (2/9), loss of peripancreatic fat plane (3/9), thickening of anterior pararenal fascia (1/9), calcification (1/9), smooth margin (2/9), and serrated margin (6/9) were observed. 4. The complications were associated with 7 cases of acute pancreatitis and 1 case of chronic pancreatitis; pseudocyst (6), abscess (2), and fat necrosis (3), The sites of the pseudocyst were lesser sac (2), anterior pararenal space (2), posterior pararenal space (1), subhepatic region (1), greater omentum (1), and intrapancreatic region (2). All of them were associated with acute pancreatitis except one in chronic pancreatitis.

Intramedullary Spinal Abscess: A Case Report

A 42-year-old male was admitted to our clinic on May 4, 1980, because of slight neck stiffness, quadriparesis and urinary difficulty. On admission, neurological examination revealed alert mental state, slight neck stiffness, quadriparesis and loss of pain and temperature sense below the level of C3 sensory dermatome. All deep tendon reflexes were hyperactive and Babinski's sign was positive. Roentgenographic examination of the cervical spine showed widened interpedicular distance at C5 to C7 in A-P view. Myelogram disclosed widening of the dye column at C4 to T1 vertebral level, suggesting intramedullary tumor. Laminectomy was performed from the C5 to T2. The cord appeared to be widened and swollen at the C6-7 segment level. 1ml of yellowish pus was aspirated from the distended spinal cord at the C6 level. Mid-line posterior myelotomy was performed and hard cavity wall was visible. Upon incision of cavity wall, about 5ml of yellowish purulent pus exuded, allowing the cord to become "flaccid". The abscess cavity was irrigated with saline and penicillin solutions and a small rubber drain catheter was placed in the abscess cavity. The organism from the abscess was identified as Staphylococcus aureus. Postoperative course was uneventful. Antibiotic therapy was continued for four weeks after operation. The patient's condition was much improved and he could walk with assistance on discharge time.

Suprasellar Cystic Meningioma Simulating Craniopharyngioma: A Case Report

An unusual case of meningioma with a large cyst on the sellar region which was misinterpreted to craniopharyngioma was reported. A 6-year-old boy was admitted to our hospital on May 8, 1980 because of headache, blurred vision and walking disturbance. On admission, neurological examination revealed marked diminished visual acuity associated with optic atrophy in both eyes, gait disturbances, incoordination and precocious puberty. Plain skull film showed marked digital markings and seperation of the coronal suture. Right carotid angiography in AP view revealed widening of the U-loop and space occupying lesion on the suprasellar region in lateral view. Neither detection of the tumor feeding artery nor tumor stain was seen. Conary ventriculography revealed marked dilation of the both lateral ventricles and blockage of the foramen of Monro. CT scan disclosed a well defined low density area and small multilobulated cysts in the suprasellar region. The margin of the tumor and low density area were markedly enhanced by contrast media. At operation, the tumor was found to consist of a yellowish brown nodule firmly adherent to the diaphragma sellae and a large cyst. The tumor was partially removed together with the whole cyst wall. The resected nodule was relatively hard and had multiple small cysts in it's cut surface. Postoperative course was uneventful. The neurological deficits except precocious puberty were much improved on discharge time. Reviewing the literature and the pathogenesis of cystic change in meningiomas were discussed.