[Derivation of Conversion Formula of Image Quality Figure (IQFinv) Values by Old and New Analysis Software for Mammographic Contrast-detail Phantom].

PURPOSE: This study deals with the conversion of the image quality figure (IQFinv) values with CDMAM Analyser ver. 1 (old analysis software) used to analyse the images of CDMAM 3.4 phantom into the IQFinv values with a new analysis software, that is, CDMAM Analyser (ver. 2 and ver. 2.3), which is a software improved to be closer to human visual evaluation. METHODS: The IQFinv values were calculated using four mammography units and three analysis software. The IQFinv values using the old and new software were compared. RESULTS: The IQFinv values had no difference according to mammography units and beam quality. The conversion formula of IQFinv from CDMAM Analyser ver. 1 to CDMAM Analyser ver. 2 was derived. Furthermore, the conversion formula of IQFinv from CDMAM Analyser ver. 1 to CDMAM Analysis ver. 2.3 was also derived. CONCLUSION: Using each conversion formula, the IQFinv values using the old software can be converted to those using the new software. There was a slight difference between the IQFinv values using the new software.

[Construction and Analysis of a Digital Mammography Database: Analysis of Breast Compression Pressures at Four Facilities].

We analyzed the compression pressures in 2772 mammography images of 807 patients acquired by digital mammography equipment at four facilities. The analysis included the average compression pressure at all facilities, difference in compression pressure at each facility, differences between the pressures used by radiological technologists in the same facility, and difference attributed to the breast structure. We also analyzed the effects of the compression pressure on the breast thickness and mean glandular dose (MGD) at each facility. The median values of the compression pressure and breast thickness for the 2772 images at all facilities were 86.5 N and 43 mm, respectively. The compression pressures differed among the institutions. The maximum difference in the median pressures among the four facilities was 38.6 N, while the difference in the breast thickness was 6 mm. The radiological technologists working at the same facility used almost the same compression pressure. However, differences between the compression pressures used by different radiological technologists were observed. The compression pressure in a dense breast was smaller than that in a non-dense breast. The difference in the compression pressure affected the breast thickness and MGD. The results of this analysis could be utilized for an optimal imaging in future digital mammography.

[Comparison between Variance and Edge Methods for Measuring Image Resolution Properties in Digital Mammography].

We studied the image resolution properties in digital mammography using the variance and edge response function methods. The associated measurements were made using a polymethylmethacrylate phantom of 0-40 mm thickness while maintaining the incident dose to the detector constant, as well as with and without using the phantom but by varying the level of exposure to the detector. The results obtained using the two methods were compared on the object plane of the mammography unit with compensation for the magnification and rejection of the scattered radiation. In this unit, the imaging process of resolution enhancement may be performed according to the phantom thickness, shape of test device, exposure level, and so on. The modulation transfer function values of the variance method were slightly higher than those of the edge method, approximately 6% at 2 cycles/mm and 8% at 4 cycles/mm without resolution enhancement processing. We concluded that the variance method is more suitable than the edge method for the constancy test or quality control because of its lower coefficient of variation.

[Comparison of Contrast to Noise Ratio and Signal Difference to Noise Ratio Based on QA and QC Guidelines in CR Mammography].

The measurement methods of contrast to noise ratio (CNR) and signal difference to noise ratio (SDNR) in digital mammography are different among several quality assurance (QA) guidelines, that is, the type of pixel value (PV), phantom shape, location of aluminum plate, and the size of region of interest (ROI) principally differ in data acquisition. We compared CNR (SDNR) obtained from three QA guidelines. They are the European Reference Organisation for Quality Assured Breast Screening and Diagnostic Services (EUREF), the International Electrotechnical Commission (IEC), and the International Atomic Energy Agency (IAEA). In EUREF and IEC, CNR was calculated using linearized pixel value (LPV). In IAEA, because the type of pixel value to use in SDNR was not specified, SDNR was calculated using PV and LPV, and CNR was calculated using LPV. Target/filter combinations are molybdenum/molybdenum (Mo/Mo) and molybdenum/rhodium (Mo/Rh). Applied various tube voltages are 25, 30, and 35 kV, and various phantom thicknesses are 20, 45, and 70 mm of polymethyl methacrylate (PMMA). The PV-SDNR of IAEA showed the largest value among the three methods, following LPV-CNR of IEC, LPV-CNR of EUREF at 20 mm PMMA thickness. In IAEA, SDNR changed by the kind of pixel value (PV or LPV). When CNR is calculated, every researcher should describe the type of guidelines, the kind of pixel value, and formula for calculation.

[Influence of Detector Radiation Damage on CR Mammography Quality Control].

Recently, radiation damage to the detector apparatus employed in computed radiography (CR) mammography has become problematic. The CR system and the imaging plate (IP) applied to quality control (QC) program were also used in clinical mammography in our hospital, and the IP to which radiation damage has occurred was used for approximately 5 years (approximately 13,000 exposures). We considered using previously acquired QC image data, which is stored in a server, to investigate the influence of radiation damage to an IP. The mammography unit employed in this study was a phase contrast mammography (PCM) Mermaid (KONICA MINOLTA) system. The QC image was made newly, and it was output in the film, and thereafter the optical density of the step-phantom image was measured. An input (digital value)-output (optical density) conversion curve was plotted using the obtained data. The digital values were then converted to optical density values using a reference optical density vs. digital value curve. When a high radiation dose was applied directly, radiation damage occurred at a position on the IP where no object was present. Daily QC for mammography is conducted using an American College of Radiology (ACR) accreditation phantom and acrylic disc, and an environmental background density measurement is performed as one of the management indexes. In this study, the radiation damage sustained by the acrylic disc was shown to differ from that of the background. Thus, it was revealed that QC results are influenced by radiation damage.

[Precision of half-value layer measurement on mammography].

The half-value layer (HVL) is an important index of the image quality or radiation risk in mammography. Radiation risk of the breast tissue is evaluated with the average glandular dose. The HVL index is indispensable for the average glandular dose computations. We investigated the influence of multiple factors that affect HVL value, such as thickness or purity of the aluminum attenuator, detector material of dosimeter, fluctuation of X-ray output, detector location in X-ray field and so on, for accurate average glandular dose computations. We found some aluminum plates about 20% thicker than nominal thickness. The HVL values between seven filter sets were different in about 5% at the maximum. In addition, we reduced a fluctuation of X-ray output with dose monitoring. Then, the standard deviation of HVL value decreased from 1.114% to 0.105%. HVL value obtained from a solid-state detector was statistically thicker than that measured by ionization chamber. It has been reported that there was a difference in the half-value layer under the influence of a heel effect by location of the measurement. Accompanied with alternation of detector location, HVL value of PCM (Konica Minolta) had a significant difference, while Novation (Siemens) and Senographe 2000D (GE) had no change.

Expression profiling of fecal colonocytes for RNA-based screening of colorectal cancer.

The early detection of colorectal cancer originating from any part of the colorectum is desirable because this cancer can be cured surgically if diagnosed early. We searched for marker genes for a fecal RNA-based colorectal cancer screening method by comparison of genome-wide expression profiles among cancerous and non-cancerous tissues, and healthy volunteer- and cancer patient-derived colonocytes from the feces, and the peripheral blood. Of 14,564 genes, only 3 (PAP, REG1A, and DPEP1) were selectable as final candidates which were expressed frequently at any stage of this cancer and were suppressed in non-cancerous tissues and also in the peripheral blood and colonocytes of healthy volunteers. Next, we directly compared fecal RNA-expression profiles between colorectal cancer patients and healthy volunteers, and found that most of the genes (92%) expressed in the colonocytes of the cancer patients were not expressed in those of the healthy volunteers. Six genes (SEPP1, RPL27A, ATP1B1, EEF1A1, SFN, and RPS11) selected randomly from 85 cancer patient-derived colonocyte-specific genes were evaluated. In total, reverse transcription-polymerase chain reaction or focused microarray of all those 9 genes detected 18 (78%) of 23 curable colorectal cancers (Dukes stages A-C), 9 or 10 (64% or 71%) of 14 early cancers with no lymph node metastasis (Dukes stage A or B) and 4 (80%) of 5 right-sided cancers. Our extensive gene list provides other markers for fecal RNA-based colorectal cancer screening.

Cytotoxicity of antimicrobial tissue conditioners containing silver-zeolite.

PURPOSE: The purpose of this study was to determine the effects of incorporating antimicrobial silver-zeolite on the in vitro cytotoxicities of five tissue conditioners against the living dermal model, which consisted of normal human dermal fibroblasts in a collagen lattice. MATERIALS AND METHODS: Samples of each tissue conditioner containing silver-zeolite (2 wt% and 5 wt%) were prepared; samples without silver-zeolite were used as a control. Cytotoxicity of each sample against the living dermal model was evaluated by cell viability with MTT assay. RESULTS: Cell viabilities for Visco-Gel, GC Soft-Liner, FITT, and SR-Ivoseal decreased with increasing silver-zeolite content. Cell viability for Shofu Tissue Conditioner showed no significant difference with degree of silver-zeolite incorporation and had higher values than other tissue conditioners. CONCLUSION: Individual compounds eluted from tissue conditioners and silver ions released from silver-zeolite might cause such cytotoxicity. The results suggest that Shofu Tissue Conditioner is a possible candidate for a novel antimicrobial tissue conditioner containing silver-zeolite because it showed the highest cell viability and the smallest influence of incorporating silver-zeolite.

Ruptured aneurysm of the sinus of valsalva coexisting with a ventricular septal defect and single coronary artery.

A 26-year-old man had been diagnosed with a cardiac murmur from birth. In 1998, he was admitted to hospital because of slight fatigue. A grade 5/6 continuous murmur was audible near the right sternal border at the second intercostal space. Doppler echocardiography detected an abnormal flow that suggested that an aneurysm of the right coronary sinus of Valsalva had ruptured into the right ventricular inflow tract. Blood tests showed a 19% step-up in oxygen saturation value between the right atrium and right ventricle, indicating a ventricular septal defect with left to right shunt. Coronary angiography revealed a single coronary artery. Surgical repair was carried out and the patient made an uneventful recovery. This rare combination of a ruptured aneurysm of the sinus of Valsalva coexisting with a ventricular septal defect and a single coronary artery has not been reported previously.