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Chinese hamster ovary (CHO) cells are major host cells for biopharmaceuticals. During culture, the chromosome number of CHO cells alters spontaneously. Here, we investigated the effects of artificial changes in the chromosome number on productivity. When cell fusion between antibody-producing CHO-K1-derived cells was induced, we observed a wide range of aneuploidy that was not detected in controls. In particular, antibody productivities were high in clone-derived cell populations that retained a diverse chromosome number distribution. We also induced aneuploid cells using 3-aminobenzamide that causes chromosome non-disjunction. After induction of aneuploidy by 3-aminobenzamide, cells with an increased chromosome number were isolated, but cells with a decreased chromosome number could not be isolated. When antibody expression vectors were introduced into these isolated clones, productivity tended to increase in cells with an increased chromosome number. Further analysis was carried out by focusing on clone 5E8 with an average chromosome number of 37. When 5E8 cells were used as host, the productivity of multiple antibodies, including difficult-to-express antibodies, was improved compared with CHO-K1 cells. The copies of exogenous genes integrated into the genome were significantly increased in 5E8 cells. These findings expand the possibilities for host cell selection and contribute to the efficient construction of cell lines for recombinant protein production.

The size-specific dose estimate (SSDE) is used for radiation dose management in computed tomography (CT) and represents patient’s absorbed dose more accurately than volume CT dose index. The relationship between SSDE and age or weight was investigated using 980 pediatric brain CT scans. Monolinear, power, and bilinear functions were fitted to the plots of SSDE against age or weight, and SSDE was estimated using the obtained functions. SSDE showed a biphasic increase with increasing age and weight: a rapid initial increase and subsequent a slow increase. Bilinear and power functions were successfully fitted to the plots, and mean estimation errors were close to 0, irrespective of the age or weight group. The standard SSDE values estimated from the obtained functions agreed well with the median values for each age or weight group. The curve-fitting method is expected to aid radiation dose management for pediatric brain CT using SSDE.

Compressed sensing-based reconstruction (CSR) is a new magnetic resonance (MR) image reconstruction method based on the compressed sensing (CS) technique. CSR suppresses ringing artifacts from truncated k-space sampling by estimating the high spatial frequency information required to support the acquired k-space data. CSR is intended to replace the existing zero-fill interpolation (ZIP) reconstruction. We investigated the usefulness of the CSR technique by obtaining sagittal T2-weighted images of the cervical spine and phantom images using CSR or ZIP. Our results indicated that the CSR technique reduces truncation artifacts compared to ZIP without prolonging the scan time or impairing image sharpness.

The aim of this study was to investigate the reliability of cerebral blood flow (CBF) measurements obtained by 3D pseudo-continuous arterial spin labeling (pCASL) imaging according to imaging parameters, scanner model, and field strength. We acquired 3D pCASL images in 12 healthy volunteers using four different scanners: two 3.0 T scanners and two 1.5 T scanners. Reliability was evaluated using intraclass correlation coefficient. Our results indicate that the influence of the post-labeling delay and scanner model on CBF measurements should be taken into consideration. If two scanners of the same model are used, scannerdependent differences may be small.

Purpose: We quantitatively investigated hepatic enhancement in gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging at 1.5T and 3.0T. Methods: A total of 40 patients who underwent Gd-EOB-DTPA-enhanced MR imaging were included in the study. Precontrast and hepatobiliary-phase images acquired at a low flip angle (FA, 12°) and hepatobiliary-phase images acquired at a high FA (30°) were analyzed. From these images, the liver-to-muscle signal intensity ratio (LMR) and liver-to-spleen signal intensity ratio (LSR) were estimated, and the contrast enhancement ratio (CER) was calculated from the liver signal, LMR, and LSR as the ratio of the low-FA hepatobiliary-phase value to the precontrast value. The coefficient of variance in the liver signal was determined to represent image noise. Results: LMR and LSR indicated similar image contrast between 1.5T and 3.0T. A higher FA provided larger LMRs and LSRs, and the degree of the FA-dependent increase was similar between 1.5T and 3.0T. CER did not differ significantly between 1.5T and 3.0T, regardless of the calculation method. A better correlation to CER calculated from the liver signal was found for the LMR-based CER values than for the LSR-based CER. The coefficient of variance in the liver signal was significantly smaller at 3.0T for precontrast and low-FA hepatobiliary-phase images, but not for high-FA hepatobiliary-phase images. Conclusion: The indices of hepatic enhancement were similar between 1.5T and 3.0T, indicating that the magnetic field strength does not substantially influence image contrast after administration of Gd-EOB-DTPA.

Purpose Image non-uniformity may cause substantial problems in magnetic resonance (MR) imaging especially when a 3-T scanner is used. We evaluated the effect of image non-uniformity correction in gadolinium ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR imaging using a 3-T scanner. Methods Two commercially available methods for image non-uniformity correction, surface coil intensity correction (SCIC), and phased-array uniformity enhancement (PURE), were applied to Gd-EOB-DTPA-enhanced images acquired at 3-T in 20 patients. The calibration images were used for PURE and not for SCIC. Uniformity in the liver signal was evaluated visually and using histogram analysis. The liver-to-muscle signal ratio (LMR) and liver-to-spleen signal ratio (LSR) were estimated, and the contrast enhancement ratio (CER) was calculated from the liver signal, LMR, and LSR. Results Without non-uniformity correction, hyperintensity was consistently observed near the liver surface. Both SCIC and PURE improved uniformity in the liver signal; however, the superficial hyperintensity remained after the application of SCIC, especially in the hepatobiliary-phase images, and focal hyperintensity was shown in the lateral segment of the left hepatic lobe after the application of PURE. PURE increased LMR dramatically and LSR mildly, with no changes in CERs. SCIC depressed temporal changes in LMR and LSR and obscured contrast effects, regardless of the method used for calculation of CER. Conclusion SCIC improves uniformity in the liver signal; however, it is not suitable for a quantitative assessment of contrast effects. PURE is indicated to be a useful method for non-uniformity correction in Gd-EOB-DTPA-enhanced MR imaging using a 3-T scanner.

Objectives We investigated the clinical usefulness of respiratory navigator-gating technique for the assessment of liver tumors in Gd-EOB-DTPA-enhanced magnetic resonance (MR) imaging. Methods Eighty patients who underwent Gd-EOB-DTPA-enhanced MR imaging to evaluate known or suspected liver tumors were enrolled. Three-dimensional spoiled gradient-recalled echo images of the liver were acquired in the hepatobiliary phase by the following three methods: breath-hold imaging, navigator-gated low-resolution imaging, and navigator-gated high-resolution imaging. Navigator-gated imaging was performed during free breathing. Spatial resolution was identical between breath-hold imaging and gated low-resolution imaging. Signal intensities in the liver, muscle, and spleen were measured in 20 patients. Image quality was visually evaluated in all 80 patients. The detection rate and lesion conspicuity were assessed for 71 malignant liver lesions identified in 29 patients. Results The liver-to-muscle and liver-to-spleen signal ratios were significantly lower for gated images compared to breath-hold images. Images of acceptable quality were obtained in most patients by all three methods, and the overall image quality of axial images did not differ significantly among the imaging methods, although superior reformatted coronal images were obtained by gated high-resolution imaging. The detection rates of malignant liver lesions were similar among the three imaging methods, although lesion conspicuity was significantly better for breath-hold imaging compared to gated imaging. Conclusions Navigator-gated imaging provided image qualities and detection rates of malignant liver lesions comparable to breath-hold imaging in Gd-EOB-DTPA-enhanced MR imaging; however, no additional benefits of high-resolution imaging were proven for lesion evaluation.

Introduction. Display contrast can be changed nonlinearly by manipulating the gamma value of the grayscale. We investigated the contrast of the hepatobiliary-phase images acquired with different flip angles (FAs) and displayed with different gamma values in Gd-EOB-DTPA-enhanced magnetic resonance imaging. Material and Methods. Twenty patients with liver tumors were studied. Hepatobiliary-phase images were acquired at low (12°) and high (30°) FAs. Low-FA images were converted to simulate images displayed with different gamma values, using ImageJ software. To assess image contrast, the liver-to-muscle signal ratio (LMR), liver-to-spleen signal ratio (LSR), contrast ratio (CR), liver signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated. Results. The LMR, LSR, and CR were higher in the high-FA images than in the low-FA original images. Although the SNR was lower in the high-FA images, indicating an increase in noise, the CNR was higher. Raising the gamma value increased the LMR, LSR, and CR, notably decreased the SNR, and slightly decreased the CNR. Conclusion. Increasing the FA enhanced image contrast, supporting its usefulness for improving the delineation of focal liver lesions. Although the associated increase in noise may be problematic, raising the grayscale gamma value enhances the display contrast of low-FA images.

We evaluated the effective dose (ED) of the CT component of whole-body PET/CT using software dedicated to CT dose estimation and from dose–length product (DLP) values to establish practical methods of ED estimation. Methods: Eighty adult patients who underwent 18F-FDG whole-body PET/CT were divided into groups A and B, each consisting of 20 men and 20 women. In group A, ED of the CT component was calculated using CT-Expo for 6 anatomic regions separately, and whole-body ED was obtained by summing the regional EDs (CT-Expo method). DLP was calculated for each of the 6 regions and multiplied by a corresponding conversion factor described in International Commission on Radiological Protection publication 102 to obtain the ED for each region (regional DLP method). Whole-body ED was also calculated as the product of a whole-body DLP value provided by the scanner automatically and a conversion factor (simple DLP method). Moreover, the ED/DLP values were calculated using whole-body ED estimated by the CT-Expo method and the scanner-derived DLP, to optimize the conversion factor. In group B, the optimized conversion factor was applied for the estimation of ED by the simple DLP method. Results: In group A, the regional DLP method allowed an accurate estimation of mean whole-body ED as a result of counterbalance of mild overestimation in men and mild underestimation in women, regarding the CT-Expo method as a standard. The simple DLP method using a conversion factor for the trunk (0.015 mSv/mGy/cm) caused overestimation. On the basis of the ED/DLP values in group A, a modified conversion factor of 0.013 mSv/mGy/cm and sex-specific conversion factors of 0.012 and 0.014 mSv/mGy/cm for men and women, respectively, were determined. In group B, the use of the modified conversion factor improved accuracy, and the use of sex-specific conversion factors eliminated sex-dependent residual errors. Conclusion: ED of the CT component of whole-body PET/CT can be assessed by multiplying the scanner-derived DLP by a conversion factor optimized for whole-body PET/CT.

Background: One of the most serious complications of stereotactic biopsy is postoperative symptomatic hemorrhage due to injury to the basal perforating arteries such as the lenticulostriate arteries neighboring the basal ganglia lesions. Objectives: A new target-planning method was proposed to reduce hemorrhagic complications by avoiding injury to the perforating arteries. Methods: Three-dimensional 3-T time-of-flight (3D 3-T TOF) imaging was applied to delineate the basal perforating arteries such as the lenticulostriate arteries. The incidence of postoperative hemorrhage in basal ganglia cases was compared between a new method using 3D 3-T TOF and a conventional target-planning method based on contrast-enhanced T1-weighted magnetic resonance images obtained by 1.5-T scanning. Results: 3D 3-T TOF imaging could delineate the basal perforating arteries sufficiently in target planning. No postoperative hemorrhage occurred with the new method (n = 10), while 6 postoperative hemorrhages occurred with the conventional method (n = 14). The new method significantly reduced the occurrence of postoperative hemorrhages (p = 0.017). Conclusions: 3D 3-T TOF MR imaging with contrast medium administration provides useful information about the perforating arteries and allows safe stereotactic biopsy of basal ganglia lesions.

To investigate a method for optimizing the display conditions of brain magnetic resonance (MR) images. We retrospectively analyzed brain MR images of 120 adults classified into screening, acute cerebral infarction, and brain tumor groups (n = 40 each). Two observers independently displayed the images on a monitor and optimized the display conditions using the W/L and U/L methods. In the W/L method, the observers manipulated the width and level of the display window, while in the U/L method they manipulated the upper and lower levels of the window. The times required were compared between the two methods. Additionally, the appropriateness of the determined window setting was evaluated visually by the respective observer to exclude the possibility that rough, suboptimal adjustment shortened the adjustment time. For both observers and all groups, the time required for optimization was significantly shorter for the U/L method than for the W/L method. The appropriateness of the window setting for the U/L method was equal to or better than that for the W/L method. Manipulating the upper and lower levels of the display window appears to improve the efficiency of interpreting brain MR images through rapid optimization of the display condition.

BACKGROUND AND PURPOSE: Arterial spin-labeling MR imaging permits safe, repeated CBF measurement. We investigated the potential and technical factors of arterial spin-labeling imaging in assessing cerebrovascular reactivity to acetazolamide. MATERIALS AND METHODS: The regional CBF was measured in 8 healthy volunteers by use of a 3D pseudocontinuous arterial spin-labeling sequence. Arterial spin labeling imaging was performed at rest and every 2 minutes after intravenous acetazolamide injection. To evaluate repeatability, regional CBF measurements were repeated without acetazolamide within an imaging session and on a separate day. Additionally, arterial spin-labeling imaging was performed at rest and after acetazolamide injection with different postlabeling delays, and regional cerebrovascular reactivity was calculated. RESULTS: The regional CBF started to increase immediately after acetazolamide injection and peaked at approximately 10 minutes, followed by a slow decrease. Favorable intrasession repeatability was demonstrated, especially when scanner tuning was omitted between scans. Rest regional CBF was slightly lower with a postlabeling delay of 2525 ms than with a postlabeling delay of 1525 ms, and the postlabeling delay–dependent difference was more evident for regional CBF after acetazolamide injection and regional cerebrovascular reactivity. CONCLUSIONS: Arterial spin-labeling imaging allows evaluation of the distribution, magnitude, and time course of cerebrovascular response to acetazolamide. The influence of the postlabeling delay on the estimated cerebrovascular reactivity should be noted.

Purpose We compared diffusion-weighted imaging (DWI) of the breast using 2 different b-values to determine the optimal b-value for greatest signal contrast between tumors and normal tissue of the breast. Materials and methods We performed DWI of the breast at b-values of 1000 s/mm(2) and 1500 s/mm(2) in 120 patients (121 lesions, 19 benign, 102 malignant) and visually scored image quality with regard to artifact and visibility of tumors. We quantitatively evaluated the signal-to-noise ratio (SNR) of the tumor and contrast-to-noise ratio (CNR) and contrast ratio (CR) between the tumor and normal breast parenchyma. Results The CR of invasive carcinoma (IC), ductal carcinoma in situ (DCIS), and benign tumors significantly improved with b=1500 s/mm(2) compared with b=1000 s/mm(2). The SNR and CNR were significantly lower with b=1500 s/mm(2) than b=1000 s/mm(2) despite the increasing number of excitations at b=1500 s/mm(2). At b=1500 s/mm(2), the difference in SNR, CNR, and CR between IC and DCIS and benign tumors was statistically significant. Conclusion DWI may depict breast tumors more clearly with b=1500 s/mm(2) than b=1000 s/mm(2).

Background We investigated a practical method to measure peak filling rate (PFR) as an indicator of diastolic function of the left ventricle. Ten adult volunteers underwent cine MR imaging using steady-state free precession (SSFP) and phase contrast (PC) sequences to measure PFR. Two PC image sets were acquired at the mitral valve orifice, and PFR was determined from the set with high true temporal resolution (temporal PC method) or with high spatial resolution (spatial PC method). SSFP images covering the left ventricle were acquired, and a time–volume curve was generated around the peak filling phase. PFR was determined using parabolic curve fitting on the first-derivative curve of the LV time–volume curve. Findings PFR values estimated by the PC methods correlated well with those estimated by the SSFP method, despite apparent underestimation. The underestimation was smaller for the temporal PC method (12 %) than for the spatial PC method (28 %). Intra- and inter-observer repeatabilities were better for the PC methods than for the SSFP method. Conclusions PFR measurement by PC imaging with high true temporal resolution is convenient and offers excellent repeatability and acceptable accuracy, indicating suitability for clinical use.

We compared the contrast effect of high and medium iodine-concentration contrast materials for preoperative CT eva- luation of breast cancer patients. Female breast cancer patients who underwent enhanced CT of the chest and upper abdomen before surgery were analyzed retrospectively. High (370 mg I/mL, 100 mL) or medium (300 mg I/mL, 125 mL) concentrations of contrast material were injected for 60 sec, followed by saline flush, and postcontrast CT images were obtained 90 sec after contrast injection. CT values were assessed for the breast tumor, normal breast parenchyma, liver, aorta, and muscle. For the high and medium concentration agents, 45 and 49 patients were analyzed, respectively. No significant differences between the two contrast agents were found in terms of CT values of the breast tumor, normal breast parenchyma, liver, aorta, or muscle. The tumor-background differences in CT values did not differ significantly between the two agents. A comparable contrast effect was indicated in single-phase CT of breast cancer patients between high and medium iodine-concentration contrast material when the total iodine dose and injection duration were identical.

Diffusion-weighted imaging provides a novel contrast mechanism in magnetic resonance (MR) imaging and has a high sensitivity in the detection of changes in the local biologic environment. A significant advantage of diffusion-weighted MR imaging over conventional contrast material-enhanced MR imaging is its high sensitivity to change in the microscopic cellular environment without the need for intravenous contrast material injection. Approaches to the assessment of diffusion-weighted breast imaging findings include assessment of these data alone and interpretation of the data in conjunction with T2-weighted imaging findings. In addition, the analysis of apparent diffusion coefficient (ADC) value can be undertaken either in isolation or in combination with diffusion-weighted and T2-weighted imaging. Most previous studies have evaluated ADC value alone; however, overlap in the ADC values of malignant and benign disease has been observed. This overlap may be partly due to selection of b value, which can influence the concomitant effect of perfusion and emphasize the contribution of multicomponent model influences. The simultaneous assessment of diffusion-weighted and T2-weighted imaging data and ADC value has the potential to improve specificity. In addition, the use of diffusion-weighted imaging in a standard breast MR imaging protocol may heighten sensitivity and thereby improve diagnostic accuracy. Standardization of diffusion-weighted imaging parameters is needed to allow comparison of multicenter studies and assessment of the clinical utility of diffusion-weighted imaging and ADC values in breast evaluation.

To compare the capability of diffusion-weighted (DW) and contrast material-enhanced magnetic resonance (MR) imaging to provide diagnostic information on residual breast cancers following neoadjuvant chemotherapy and to assess apparent diffusion coefficients (ADCs) of the carcinoma prior to neoadjuvant chemotherapy to determine if the method could help predict response to chemotherapy.Institutional review board approval and informed consent were obtained. Three hundred ninety-eight patients underwent MR imaging of the breast, including DW MR (b values, 0 and 1500 sec/mm(2)) and contrast-enhanced MR imaging. Of these, the contralateral breast in 73 women was used as a control. Seventy-two patients with 73 lesions with malignant disease were treated by using neoadjuvant chemotherapy and were examined for residual disease following therapy. Three were excluded because of prolonged intervals between final MR imaging and surgery. Thus, 69 patients (70 lesions) with DW and contrast-enhanced MR imaging results were compared with postoperative histopathologic findings. The ADCs of the carcinoma prior to neoadjuvant chemotherapy were calculated for each patient, and those with complete response and residual disease were compared.The accuracy for depicting residual tumor was 96% for DW MR imaging, compared with an accuracy of 89% for contrast-enhanced MR imaging (P = .06). There was no significant difference in prechemotherapy ADCs between pathologic complete response cases and those with residual disease.DW MR imaging had at least as good of accuracy as did contrast-enhanced MR imaging for monitoring neoadjuvant chemotherapy. The ADCs prior to chemotherapy did not predict response to chemotherapy. The use of DW imaging to visualize residual breast cancer without the need for contrast medium could be advantageous in women with impaired renal function.

Dose-length product (DLP) is widely used as an indicator of the radiation dose in computed tomography. The aim of this study was to investigate the significance of sex and body weight in DLP-based monitoring of the radiation dose. Eight hundred computed tomographies of the chest performed using four different scanners were analysed. The DLP was compared with body weight by linear regression in men and women separately. The DLP was positively correlated with body weight, and dependence on sex and weight differed among scanners. Standard DLP values adjusted for sex and weight facilitated interscanner comparison of the radiation dose and its dependence on sex and weight. Adjusting the DLP for sex and weight allowed one to identify examinations with possibly excessive doses independently of weight. Monitoring the DLP in relation to sex and body weight appears to aid detailed comparison of the radiation dose among imaging protocols and scanners and daily observations to find unexpected variance.

Purpose: The purpose of this study was to investigate the utility of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) value in differentiating benign and malignant breast lesions and evaluating the detection accuracy of the cancer extension. Materials and Methods: We used DWI to obtain images of 191 benign and malignant lesions (24 benign, 167 malignant) before surgical excision. The ADC values of the benign and malignant lesions were compared, as were the values of noninvasive ductal carcinoma (NIDC) and invasive ductal carcinoma (IDC). We also evaluated the ADC map, which represents the distribution of ADC values, and compared it with the cancer extension. Results: The mean ADC value of each type of lesion was as follows: malignant lesions, 1.22±0.31×10-3 mm2/s; benign lesions, 1.67±0.54×10-3 mm2/s; normal tissues, 2.09±0.27×10-3 mm2/s. The mean ADC value of the malignant lesions was statistically lower than that of the benign lesions and normal breast tissues. The ADC value of IDC was statistically lower than that of NIDC. The sensitivity of the ADC value for malignant lesions with a threshold of less than 1.6×10-3 mm2/s was 95% and the specificity was 46%. A full 75% of all malignant cases exhibited a near precise distribution of low ADC values on ADC maps to describe malignant lesions. The main causes of false negative and underestimation of cancer spread were susceptibility artifact because of bleeding and tumor structure. Major histologic types of false-positive lesions were intraductal papilloma and fibrocystic diseases. Fibrocystic diseases also resulted in overestimation of cancer extension. Conclusions: DWI has the potential in clinical appreciation to detect malignant breast tumors and support the evaluation of tumor extension. However, the benign proliferative change remains to be studied as it mimics the malignant phenomenon on the ADC map.

We evaluated the usefulness of two-dimensional time-of-flight (2D TOF) MR venography (MRV) of the lower extremity using the respiratory compensation (RC) technique. In addition, six variations in patient positioning of the leg and knee were investigated to determine the best method of visualizing the deep popliteal veins and lower leg. All data sets were reviewed and graded for visualization of the deep veins at the pelvis, thigh, and leg portion (4-point scale) by two radiologists and three radiological technologists. The same veins demonstrated with various positions of the patient were also evaluated in the same manner. In conclusion, 2D TOF MRV with RC resulted in increased uniformity of vein signal in the pelvic area. Furthermore, we should position the patient's leg so as not to compress the vein at the posterior portion of the leg, and not to over-extend the knee joint. This enabled the best results to be obtained in MRV of the lower extremity.

We evaluated the effective dose (ED) of the CT component of whole-body PET/CT using software dedicated to CT dose estimation and from dose-length product (DLP) values to establish practical methods of ED estimation.Eighty adult patients who underwent (18)F-FDG whole-body PET/CT were divided into groups A and B, each consisting of 20 men and 20 women. In group A, ED of the CT component was calculated using CT-Expo for 6 anatomic regions separately, and whole-body ED was obtained by summing the regional EDs (CT-Expo method). DLP was calculated for each of the 6 regions and multiplied by a corresponding conversion factor described in International Commission on Radiological Protection publication 102 to obtain the ED for each region (regional DLP method). Whole-body ED was also calculated as the product of a whole-body DLP value provided by the scanner automatically and a conversion factor (simple DLP method). Moreover, the ED/DLP values were calculated using whole-body ED estimated by the CT-Expo method and the scanner-derived DLP, to optimize the conversion factor. In group B, the optimized conversion factor was applied for the estimation of ED by the simple DLP method.In group A, the regional DLP method allowed an accurate estimation of mean whole-body ED as a result of counterbalance of mild overestimation in men and mild underestimation in women, regarding the CT-Expo method as a standard. The simple DLP method using a conversion factor for the trunk (0.015 mSv/mGy/cm) caused overestimation. On the basis of the ED/DLP values in group A, a modified conversion factor of 0.013 mSv/mGy/cm and sex-specific conversion factors of 0.012 and 0.014 mSv/mGy/cm for men and women, respectively, were determined. In group B, the use of the modified conversion factor improved accuracy, and the use of sex-specific conversion factors eliminated sex-dependent residual errors.ED of the CT component of whole-body PET/CT can be assessed by multiplying the scanner-derived DLP by a conversion factor optimized for whole-body PET/CT.

The purposes of this study were to compare the apparent diffusion coefficient (ADC) of mucinous carcinoma of the breast with that of other breast tumors and to analyze correlations between signal intensity on diffusion-weighted images and the histologic features of mucinous carcinoma.Two hundred seventy-six patients with 277 lesions, including 15 mucinous carcinomas (13 pure type, two mixed type), 204 other malignant tumors, and 58 benign lesions, were examined with 1.5-T MRI at b values of 0 and 1,500 s/mm(2). The correlations between cellularity and ADC, homogeneity of signal intensity on diffusion-weighted images, and histopathologic findings were analyzed. The difference was statistically significant (p0.05).The mean ADC of mucinous carcinoma (1.8 +/- 0.4 x 10(-3) mm(2)/s) was statistically higher than that of benign lesions (1.3+/- 0.3 x 10(-3) mm(2)/s) and other malignant tumors (0.9 +/- 0.2 x 10(-3) mm(2)/s) (p0.001). The ADC of pure type mucinous carcinoma (1.8 +/- 0.3 x 10(-3) mm(2)/s) was higher than that of mixed type mucinous carcinoma (1.2 +/- 0.2 x 10(-3) mm(2)/s) (p0.001) and other histologic types (p0.05). The correlation between mean cellularity and the ADC of mucinous carcinoma was significant (rho(s) = -0.754; p = 0.001). The homogeneity of signal intensity on diffusion-weighted images correlated with the homogeneity of histologic structures of mucinous carcinoma (p0.001; kappa = 0.826).Mucinous carcinoma can be clearly differentiated from other breast tumors on the basis of ADC. The low signal intensity of mucinous carcinoma on diffusion-weighted images appears to reflect the presence of mucin and low cellularity. High signal intensity on diffusion-weighted images may reflect the presence of fibrovascular bundles, increased cell density, or a combination of these features.

The authors used breast diffusion-weighted imaging (DWI) to diagnose breast cancer and identify cancer extension. Isotropic DWI was performed with EPI. The apparent diffusion coefficient (ADC) value was calculated and displayed on an ADC map. The authors compared between the distribution of low ADC values and pathologic cancer extension. The mean ADC value of breast cancer was 1.12 +/- 0.24 x 10(-3) mm/s, which was lower than that of normal breast tissue. The ADC value for invasive ductal carcinoma was lower than that of noninvasive ductal carcinoma. The sensitivity of the ADC value for breast cancer using a threshold of less than 1.6 x 10(-3) mm/s was 95%. Seventy-five percent of all cases showed precise distribution of low ADC value as cancer extension. The causes of underestimation were susceptibility artifact from bleeding and the limit of spatial resolution. Benign proliferative change showed a low ADC value. The authors conclude that DWI has a potential for clinical appreciation in detecting breast cancer.

AIM Super-paramagnetic iron oxide-enhanced magnetic resonance imaging (SPIO-MRI) is highly sensitive for liver tumors. This trial examined the optimal parameters of the fast recovery fast spin echo (FRFSE) method in SPIO-MRI. The FRFSE method is a pulse sequence with recovery of the compulsory longitudinal magnetization. The FRFSE method used in SPIO-MRI has better sensitivity for liver tumor, better tumor contrast, and can be used with respiratory gating. MATERIALS AND METHODS The phantoms used included a ferucarbotran phantom, water phantom, and gelatin phantom. Each phantom was scanned by the FRFSE method and fast spin echo (FSE) method, with changing of scanning parameters, and each CNR was measured. Each CNR was given a point, and points were averaged according to each parameter. Parameters that obtained high average points were considered optimal parameters. RESULTS The optimal parameters were set to TE=50 ms in the FRFSE method. The scan parameters optimized from the phantom study were used in a clinical case, and good results were achieved, as in the phantom study. CONCLUSION We optimized the scan parameters of the FRFSE method and were able to suggest the usefulness of the FRFSE method in SPIO-MRI.

We performed CT-angiography twice, first hip joint extension, followed by second flexion. Using vessel analysis software, we placed several points of interest at equal intervals on the center line of the iliac artery, from the bifurcation to the femoral artery inguinal portion, and recorded the their three-dimensional coordinates. We also marked the circumference, which passes by three points that add the respective next point and prior point to each reference point. This curvature (the inverse number of the radius) was utilized as the index that displays crookedness. This method was able to estimate quantitatively the grade of crookedness, and, by comparing an equidistant point from the bifurcation, to show the changes in grade at flexion of the hip joint.