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This report presents a new method to characterize the inappropriate positioning of dosimeters based on the dose equivalent Hp(10). The Hp(10) values of medical workers were measured monthly for 12 mo using two personal dosimeters. Using the ratio between the values of Hp(10) recorded from dosimeters worn over and under protective aprons [Hp(10) over and Hp(10) under , respectively], 670 pairs of dosimeter readings were categorized into a proper use group [Hp(10) over /Hp(10) under ≥ 5] and a misuse group [Hp(10) over /Hp(10) under5]. Following personal interviews, the readings in the misuse group were classified into the following six subgroups: "reversed," "sometimes reversed," "both under," "both over," "without apron," and "not specified." Ultimately, the scatter plot of "Hp(10) over - Hp(10) under " vs. Hp(10) over was identified as the most promising tool for clarifying the misuse patterns of dosimeters, as individual readings were mapped to the locations of the corresponding subgroups in the obtained graphs. Our results are expected to facilitate efficient and accurate usage of dosimeters by medical workers.

Purpose Organ-based tube current modulation (OB-TCM) techniques, which are provided by three vendors, reduces the radiation dose to the lens of the eyes by decreasing the tube current, when the X-ray tube passes over the anterior surface of critical organs. However, the characteristics of dose modulation of these techniques are different. The purpose of this study was to understand the performance characteristics of OB-TCM technique of each computed tomography (CT) vendor at head CT. Methods We used three CT scanners (SOMATOM Definition Flash; Siemens Healthcare, Revolution CT; GE Healthcare, and Aquilion ONE Genesis Edition; Canon Medical Systems). We measured the radiation dose to the lens surface as evaluation of radiation dose reduction and measured the image noise as index of image quality. We measured the radiation dose rate in the air for analysis of the characteristics of dose modulation in each OB-TCM. Results When applying OB-TCM, the radiation doses for the lens surface were decreased by 28%, 22%, and 25% for Siemens, GE, and Canon CT scanners, respectively, and the image noise level was increased by 5.6%, 8.5%, and 15.1% for Siemens, GE, and Canon CT scanners, respectively. The characteristics of dose modulation in each OB-TCM were also confirmed by measured the radiation dose rate. Conclusion We confirmed that each OB-TCM has different influence on image quality and radiation doses for lens surface, due to the different characteristics of dose modulation for each CT vendor.

Background The purpose of this study was to evaluate bone tunnel changes following anterior cruciate ligament (ACL) reconstruction during the early postoperative period using computed tomography (CT), and to understand the impact of postoperative immobilization on these changes. Methods Twenty patients who underwent double-bundle ACL reconstruction using hamstring tendon autografts were included. We subcategorized patients into two groups: patients who underwent isolated ACL reconstruction and had three days of knee immobilization (Group A, n = 10); and patients with concomitant meniscus injuries who underwent ACL reconstruction and meniscus repair simultaneously (Group B, n = 10) had their knees immobilized for two weeks after surgery. Bone tunnel enlargement was evaluated using CT imaging at one to three days, two weeks, one month, three months and six months after surgery. The cross-sectional area of the femoral and tibial tunnels was measured, and enlargement rate was calculated. The tunnel center location at two weeks after surgery was also evaluated. Results The mean cross-sectional area adjacent to the joint space of the femoral and tibial tunnels significantly increased immediately after surgery, especially in the first month (P 0.01). There was no significant difference in tunnel enlargement rate between group A and B. Tunnel center location changed even in the first two weeks. Conclusions Bone tunnel enlargement following double-bundle ACL reconstruction occurred at an earlier time point after surgery than anticipated. Postoperative immobilization could not prevent bone tunnel enlargement, but might prevent tunnel migration.

One of the most important and useful pieces of information in the preoperative evaluation of a large petroclival meningioma is the running course of the abducens nerve. The abducens nerve is small and has a long intracranial course, making it prone to compression by the tumor at various anatomical points. In relatively large tumors, it is difficult to confirm the entire course of the abducens nerve, even by heavy T2-thin slice imaging. We report a case of successful preoperative estimation of the course of the abducens nerve that aided in its complete preservation during the resection of a large petroclival tumor.

Purpose Dual-energy computed tomography (DECT) can provide iodine, electron density (ED), and effective atomic number Z (Zeff) maps, facilitating the identification of tissue types. We investigated whether DECT parameters can predict the vascularity of meningiomas. Method We acquired DECT and perfusion CT (PCT) images in 24 patients with histologically diagnosed meningioma. Regions of interest (ROIs) were placed at the tumor in iodine, ED, and Zeff maps derived from DECT and in a blood volume (BV) map derived from PCT. To normalize these parameters' values, we divided them by the values of contralateral normal-appearing white matter, i.e., the relative (r)ED, rZeff, and rBV. The vascular density of the tumor specimens was immunohistochemically analyzed by calculating the von Willebrand factor-positive vessel wall. We calculated Pearson's correlation coefficients to determine the correlation with PCT/DECT parameters and an immunohistopathological index. Results Contrast rZeff (r = 0.7020, p = 0.0001) and iodine (r = 0.5814, p = 0.0029) both had positive correlations with rBV derived from PCT. The rED values were negatively correlated with the rBV values (r = −0.4735, p = 0.0194), and the vascular density results confirmed positive correlations with rBV (r = 0.6909, p = 0.0002) and contrast rZeff (r = 0.4982, p = 0.0132) and a negative correlation with rED (r = −0.4265, p = 0.0377). Regarding the radiation exposure, the mean estimated volume CT dose index (CTDIvol) of DECT was 33.1 ± 1.72 mGy, much lower than that of PCT (103.3 ± 4.65 mGy). Conclusions DECT predicted vascular density with lower radiation exposure compared to PCT. DECT could potentially replace PCT for evaluating the vascularity of meningiomas.

Background Perfusion computed tomography (PCT) reflects blood flow and capillary condition, which is valuable in assessing brain tumors. We evaluated PCT parameters at the tumor (t) and peritumoral (p) region to differentiate malignant brain tumors. Methods We performed PCT in 39 patients with supratentorial malignant brain tumors (22 glioblastomas, 6 lymphomas, 11 metastases). Regions of interests were placed manually at tumor, peritumoral region, and contralateral normal-appearing white matter. Cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and permeability surface (PS) were measured. These parameters were divided by those of contralateral normal-appearing white matter to normalize at tumor (relative [r]CBVt, rCBFt, rMTTt, rPSt) and peritumoral regions (rCBVp, rCBFp, rMTTp, rPSp). The parameters were evaluated with Mann–Whitney U test and receiver operating characteristics analyses. Stepwise analyses also were performed to select useful PCT parameters for differentiating these tumors. Results The rCBFt and rCBVt of glioblastoma (GBM) were greater than those of primary central nervous system lymphoma (PCNSL) (P = 0.0005, 0.0002) and brain metastasis (METS) (P = 0.0044, 0.0028). The rMTTp of METS was greater than that of GBM and PCNSL (P = 0.0001, 0.0007). The combination of rCBVt and rPSt could differentiate GBM from other tumors with sensitivity and specificity of 81.8% and 94.1%. The combination of rCBFp and rMTTp could differentiate METS from other tumors with sensitivity and specificity of 90.9% and 82.1%. Conclusions Our study introduces and supports the usefulness of PCT parameters for differentiation among GBM, PCNSL, and METS. rCBVt and rPSt may be the best predictors of GBM. rCBFp and rMTTp may be the best predictors of METS.

The aim of this study was to ascertain the ideal far anteromedial portal location to avoid damaging the medial femoral condyle in anterior cruciate ligament (ACL) reconstruction. Forty patients received preoperative computed tomography (CT) scans at 120° of knee flexion. Three-dimensional CT (3D CT) reconstruction of the knee was performed using volume rendering. The insertion of anteromedial (AM) and posterolateral bundle of ACL of the femur was marked on the 3D CT. A line (Line A) was drawn 8-mm proximal and parallel to the anterior ridge of the medial tibial plateau. A tangential line to the medial femoral condyle was drawn from the AM position that was already marked to Line A. The length from the intersection of the lines to the medial edge of the patellar tendon was measured. In all 40 patients, the mean length between the medial edge of the patellar tendon and the far anteromedial portal was 27.5 ± 0.7 mm (range 19.8–34.5). In men 29.5 ± 0.7 mm (range 25–34.5); 28.7 ± 0.8 mm in the shorter group (height ≤ 170 cm) and 30.1 ± 1.2 mm in the taller group (height ≥ 170 cm). In women 25.5 ± 1.0 mm (range 19.8–30.5); 22.9 ± 1.0 mm in the shorter group (height ≤ 158 cm) and 29.6 ± 0.5 mm in the taller group (height ≥ 158 cm). An optimum far anteromedial portal position was proposed. Knowing the optimum location of the far anteromedial portal position before surgery allows the surgeons to perform more safety ACL reconstruction. IV.

Objective The current standard treatment protocol for patients with newly diagnosed glioblastoma (GBM) includes surgery, radiotherapy, and concomitant and adjuvant temozolomide (TMZ). We hypothesized that the permeability surface area product (PS) from a perfusion computed tomography (PCT) study is associated with sensitivity to TMZ. The aim of this study was to determine whether PS values were correlated with prognosis of GBM patients who received the standard treatment protocol. Methods This study included 36 patients with GBM that were newly diagnosed between October 2005 and September 2014 and who underwent preoperative PCT study and the standard treatment protocol. We measured the maximum value of relative cerebral blood volume (rCBVmax) and the maximum PS value (PSmax). We statistically examined the relationship between PSmax and prognosis using survival analysis, including other clinicopathologic factors (age, Karnofsky performance status [KPS], extent of resection, O6-methylguanine-DNA methyltransferase [MGMT] status, second-line use of bevacizumab, and rCBVmax). Results Log-rank tests revealed that age, KPS, MGMT status, and PSmax were significantly correlated with overall survival. Multivariate analysis using the Cox regression model showed that PSmax was the most significant prognostic factor. Receiver operating characteristic curve analysis showed that PSmax had the highest accuracy in differentiating longtime survivors (LTSs) (surviving more than 2 years) from non-LTSs. At a cutoff point of 8.26 mL/100 g/min, sensitivity and specificity were 90% and 70%, respectively. Conclusions PSmax from PCT study can help predict survival time in patients with GBM receiving the standard treatment protocol. Survival may be related to sensitivity to TMZ.

Adaptive iterative reconstruction techniques (IRs) can decrease image noise in computed tomography (CT) and are expected to contribute to reduction of the radiation dose. To evaluate the performance of IRs, the conventional two-dimensional (2D) noise power spectrum (NPS) is widely used. However, when an IR provides an NPS value drop at all spatial frequency (which is similar to NPS changes by dose increase), the conventional method cannot evaluate the correct noise property because the conventional method does not correspond to the volume data natures of CT images. The purpose of our study was to develop a new method for NPS measurements that can be adapted to IRs. Our method utilized thick multi-planar reconstruction (MPR) images. The thick images are generally made by averaging CT volume data in a direction perpendicular to a MPR plane (e.g. z-direction for axial MPR plane). By using this averaging technique as a cutter for 3D-NPS, we can obtain adequate 2D-extracted NPS (eNPS) from 3D NPS. We applied this method to IR images generated with adaptive iterative dose reduction 3D (AIDR-3D, Toshiba) to investigate the validity of our method. A water phantom with 24 cm-diameters was scanned at 120 kV and 200 mAs with a 320-row CT (Acquilion One, Toshiba). From the results of study, the adequate thickness of MPR images for eNPS was more than 25.0 mm. Our new NPS measurement method utilizing thick MPR images was accurate and effective for evaluating noise reduction effects of IRs.

Objective: We preoperatively assessed varicose veins by means of computed tomography (CT) with contrast injection in the veins of the lower extremity (CT venography). This paper reports the procedures, results and implications of CT venography from the surgical aspect. Methods: A total of 48 legs in 39 patients were examined. Contrast medium was diluted ten-fold and injected into the lower extremity veins, often using a dual route of injection. The images were reconstructed with the volume-rendering method. Results: CT venography clearly visualized the veins with a small amount of contrast medium and facilitated the identification of anatomy that was not suitable for passing the stripper. In addition, CT venography helped identify unusual types of varicose veins or uncommon sites of inflow of small saphenous veins. Such information was helpful for avoiding unexpected vascular injury or for minimizing skin incision. Dual-route injection was beneficial to minimize the blind zones. Doppler ultrasound could be more focused on hemodynamic assessment and determination of incision sites. Conclusions: CT Venography is feasible in all cases of varicose veins. When performed in conjunction with ultrasonography, it appears to facilitate the safe and efficient treatment of various types of varicose veins.

Interferon (IFN) therapy with or without ribavirin treatment is well established as a standard antiviral treatment for hepatitis C virus (HCV)–infected patients. However, susceptibility to thrombocytopenia is a major obstacle for initiating or continuing this therapy, particularly in liver transplant (LTx) recipients with HCV. Studies have reported that splenectomy performed concurrently with LTx is a feasible strategy for conditioning patients for anti-HCV IFN therapy. However, the relationship between the severity of splenomegaly and alterations in the blood cytopenia in LTx recipients remains to be clarified. Here, we analyzed the relationship between spleen volume (SV) and thrombocytopenia in 45 patients who underwent LTx at Hiroshima University Hospital. The extent of pre-LTx splenomegaly [the SV to body surface area (BSA) ratio in an individual] was inversely correlated with both the post-LTx white blood cell count and platelet (PLT) count (P < 0.001). Furthermore, the PLT count of patients with thrombocytopenia (PLT count ≤ 5 × 104/mm3) increased significantly in the group without splenomegaly (SV/BSA value < 400) versus that in the group with splenomegaly (P = 0.005). Thus, if both splenomegaly and thrombocytopenia coexist (PLT count ≤ 5 × 104/mm3 and SV/BSA value ≥ 400), persistent thrombocytopenia is predictable after LTx. Liver Transpl 15:208–215, 2009. © 2009 AASLD.

We investigated and evaluated the detection of simulated lesions in various interstitial lung diseases using the dual-energy subtraction radiography method and flat-panel detector (FPD) images. We obtained a FPD system (GE Revolution XR/d), and employed dual-energy 60 kV and 130 kV exposure techniques. Three types of lung lesions, namely, micro-nodule, ground-glass, and honeycomb patterns were simulated with interstitial lung disease on a chest phantom. Chest images with and without simulated lesions were exposed and compared with standard images and subtraction images. We carried out evaluations with and without subtraction images and performed the analysis by using receiver operating characteristic (ROC) analysis of detection. Results showed that the detection of interstitial lung diseases was significantly improved by the use of subtraction images. The area under the ROC curve (AUC) values of micro-nodule images obtained with and without subtraction images were 0.768 and 0.963, ground-glass images 0.670 and 0.917, and honeycomb images 0.768 and 0.996, respectively. A significant difference of p

Rationale and Objectives The therapeutic response to radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) often is evaluated by comparing pre- and post-RFA computed tomography (CT). However, judgment about whether an ablative margin, ie, 5–10 mm of normal hepatic tissue, is ensured sometimes is difficult. The aim of this study is to assess the feasibility of fusion images of pre- and post-RFA CT. Materials and Methods HCCs (n = 20) sized 13 ± 5 mm (range, 4–23 mm) were included. For pre-RFA CT, the arterial phase of intravenous dynamic CT (n = 17), CT arterioportography (n = 2), and CT hepatic arteriography (n = 1) was used. Using automatic image registration software (n = 20) and a manual segmentation technique (n = 4), fusion images were created in combination with post-RFA CT (equilibrium phase of intravenous CT). Results Automatic image registration and manual segmentation technique took approximately 2–3 and 5 minutes, respectively. Total time required for the creation of fusion images was less than 10 minutes in all cases. Fusion images enabled easier understanding of the relationship between the tumor and ablation zone, helping judge whether an ablative margin was ensured. Conclusion Fusion of pre- and post-RFA CT images is considered a feasible tool in the evaluation of RFA therapy for HCC.

Slow heart rate and small changes in heart rate are factors for improving image quality on spiral cardiac computed tomography (CT). The purpose of this study is to investigate whether it is possible to improve non-enhanced cardiac CT quality by delaying the data-acquisition window after breath hold.Electrocardiograph files (n = 240) for 16-slice non-enhanced cardiac CT scans were analyzed. Mean heart rates and maximal changes in heart rates between adjacent cardiac cycles were compared between phase 1 (defined as cardiac cycles 1-5), phase 2 (cardiac cycles 2-6), ... , and phase 6 (cardiac cycles 6-10).Heart rates gradually increased by phases, but were limited to a range of 66.8-68.0 beats/min. Maximal changes in heart rates were 2.5 beats/min (phase 1) at the highest and 1.3 beats/min (phases 5 and 6) at the lowest (t-test; P.01). Maximal changes in heart rates for more than five beats/min occurred in 24, eight, and eight patients on phases 1, 5, and 6, respectively (chi-square test; P.01).The delayed scan (four or five cardiac cycles after breath hold) has the potential to improve the quality of non-enhanced cardiac CT.

Multidetector row CT is a feasible diagnostic tool in pre- and postoperative liver partial transplantation. We can assess vascular anatomy and liver parenchyma as well as volumetry, which provide useful information for both donor selection and surgical planning. Disorders of the vascular and biliary systems are carefully observed in recipients. In addition, we evaluate liver regeneration of both the donor and the recipient by serial volumetry. We present how multidetector row CT with state-of-the-art three-dimensional volume renderings may be used in right lobe liver transplantation.

In recent years, laparoscopic surgery has attracted attention as a minimally invasive type of surgery because of the small surgical wounds and early recovery it provides. We carry out this technique on the basis of volume data that we make use of in multi-slice CT imaging technology in laparoscopic nephrectomy by the retroperitoneal approach, and we have created CT virtual laparoscopy by virtual endoscopic display as an intra-operative navigatior with an image analysis system. We provide information on detailed vascular anatomy to form intra-operative images that act as similar support images. With the provision of this volume data, we consider virtual endoscopic display the most suitable method for surgery. When we perform virtual laparoscopy, we simulate the insertion point and angle, the order of vascular structures and their locations, the number of arteries and veins, and their bifurcation points and ligation points in conjunction with the surgeon prior to operation. As the branch patterns of the renal artery are varied, perioperative confusion and surgical mishaps can be avoided through the information that is provided beforehand. Thus surgery is more accurate and proceeds more smoothly, because the surgeon has accurate anatomical information. In addition, the time required for surgery is decreased, reducing risk and the possibility of complications.

PURPOSE: For emergency or pediatric head CT scans, a simplified pillow made of hard sponge instead of a dedicated head holder may be used if it is difficult to immobilize the head. However, the radiation dose when using a simplified head holder may be increased due to radiation absorption by the patient couch if the automatic exposure control (AEC) system is used. In this phantom study, we compared the radiation dose delivered when using a dedicated and a simplified head holder. MATERIALS AND METHODS: We used a dedicated-type and a pillow-type head holder made of hard sponge (simplified head holder). We placed a 20 cm-diameter cylindrical phantom made of water-equivalent material and an anthropomorphic head phantom in the head holders and then scanned them five times with a 64-detector CT scanner (VCT, GE Healthcare). We performed step-and-shoot and helical scanning with AEC; the noise index was set to 2.8. We measured the radiation dose using fluorescent glass dosimeters in the head phantom and the image noise at five sites in the cylindrical phantom. All values were averaged. RESULTS: With step-and-shoot scans, the mean image noise with the dedicated and the simplified head holder was 3.30 ± 0.05 [SD] and 3.20 ± 0.05, respectively. With helical scans they were 3.00 ± 0.09 and 2.88 ± 0.03, respectively. There was no statistically significant difference (p = 0.02 and 0.04, Student's t-test). The radiation doses with the dedicated and the simplified head holder were 58.6 and 70.4 mGy, respectively, for step-and-shoot scanning and 41.8 and 49.0 mGy, respectively, for helical scanning. The doses were thus significantly higher with the simplified head holder for both step-and-shoot and helical scanning (p < 0.01 and < 0.01). CONCLUSION: We recommend the use of a dedicated head holder for head scanning with AEC since the radiation dose was lower than with the simplified head holder.

This 4-year-old girl fell while holding plastic chopsticks and a chopstick penetrated her left eye. The chopstick was removed immediately by herself. Conventional CT and MR images showed a penetration track from the orbital roof to the basal ganglia. On susceptibility-and diffusion-weighted images the track and surrounding cytotoxic edema were visualized more clearly. Although antibiotics were started at the time of admission to prevent intracranial infection, she developed meningitis. Subsequent treatment with carbapenem antibiotic-and vancomycin therapy was curative and she was discharged home 4 weeks after the injury. In our review of the literature on intracranial penetrating injuries via the orbita we compared the injury patterns inflicted by and the clinical observations reported on damage induced by wooden-, plastic-, and metal chopsticks. We also evaluated diagnostic CT and MR images in patients with intracranial penetrating injuries caused by chopsticks and documented the advantage of susceptibility-and diffusion-weighted imaging over conventional CT-and MR imaging.

The purpose of the study was to examine changes in splenic volume among recipients during the course of adult-to-adult living donor liver transplantation (LDLT) using multislice computed tomography (CT) scanning with a semiautomatic volumetry software.Forty-eight patients, including 33 males and a mean overall age of 54 +/- 8 years), underwent liver transplantation for the primary disease of liver cirrhosis with or without hepatocellular carcinoma (n = 31/17, respectively). The mean MELD score was 14 +/- 6. The liver graft mass compared with recipient weight was 74% +/- 28%. Splenic artery embolization was not performed. Dynamic CT scans splenic volume, and platelet counts (10(3)/cm(3)) were obtained pre,or =50 day andor =90 days postoperatively.The total time to generate volumetry and image postprocessing per examination was10 minutes. One-factor analysis of variance (ANOVA) revealed that the average splenic volume tended to be reduced from pre- to post-LDLT, although not significantly: pre-LDLT, 469 +/- 270 mL;or =day 50, 369 +/- 212 mL; andor =day 90, 378 +/- 210 mL (P = .066). One-factor ANOVA revealed that the average platelet count was significantly different in the 3 periods: pre-LDLT, 69 +/- 32 x 10(3)/cm(3);or =day 50, 181 +/- 253 x 10(3)/cm(3); andor =day 90, 126 +/- 64 x 10(3)/cm(3) (P.01). The post hoc Scheffé test revealed the statistical significance of the platelet counts between pre-LDLT andor =day 50 (P.01).Splenic volumetry with multislice CT and semiautomatic software, which is simple and not time consuming, was able to evaluate remission from hypersplenism during the course of LDLT.

Background Interferon (IFN) therapy is a well-established antiviral treatment for hepatitis C virus (HCV) − infected patients. However, susceptibility to thrombocytopenia is a major obstacle in its initiation or continuation, particularly in patients with HCV who underwent liver transplantation (LT). We previously showed that the coexistence of splenomegaly and thrombocytopenia could result in persistent thrombocytopenia after LT. Here we retrospectively evaluated the validity of this criterion for simultaneous splenectomy in recipients with HCV. Patients and Methods Subjects included 36 recipients with HCV who received LT between January 2006 and February 2012 at Hiroshima University. We analyzed the spleen volume, body surface area, platelet (PLT) count, and rate of completion or continuation with IFN therapy in these recipients. Result Of these recipients, 30 did not require simultaneous splenectomy according to the criterion, and 24 actually did not receive simultaneous splenectomy. In this group, 21 (87.5%) started IFN therapy. Fifteen (71.4%) of these recipients completed or continued IFN therapy, whereas 13 (61.9%) achieved either a sustained virological response (SVR) or an end-of-treatment response. The PLT count increased to >100,000/mm 3 1 month after LT in 16 (66.7%) recipients from this group. Conclusion Our criterion detected the PLT count outcome after LT in recipients with HCV and achieved a better SVR result after IFN therapy.

Purpose The aim of this study was to compare the calcium score and reproducibility of coronary artery calcium scores obtained on the four kinds of 64-detector computed tomography (CT) scanners using standard (120 kVp) and low tube voltage (80 kVp) scan techniques. Materials and Methods We scanned 80 and 120 kVp on all scanners. We calculated Agatston, volume, and mass scores for coronary artery calcium scoring on each scanner and compared the coefficients of variation of the calcium scores to evaluate reproducibility of among CT scanners. Results The averages of the total mean Agatston score, total mean volume score, and total mean mass score at 80kVp/120kVp were 798.9/683.8, and 627.2/567.3, and 157.1/156.7, respectively. The total mean mass score was almost constant irrespective of the tube voltage. The total mean coefficients of variation for the four CT scanners were lower at 80 than 120 kVp (4.1% vs. 10.2% [total mean Agatston score], 3.2% vs. 9.6% [total mean volume score], and 3.2% vs. 9.4% [total mean mass score]). Conclusion Use of the low tube voltage technique can reduce variations in the coronary artery calcium scores obtained on different CT scanners.

The therapeutic response to radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) often is evaluated by comparing pre- and post-RFA computed tomography (CT). However, judgment about whether an ablative margin, ie, 5-10 mm of normal hepatic tissue, is ensured sometimes is difficult. The aim of this study is to assess the feasibility of fusion images of pre- and post-RFA CT.HCCs (n = 20) sized 13 +/- 5 mm (range, 4-23 mm) were included. For pre-RFA CT, the arterial phase of intravenous dynamic CT (n = 17), CT arterioportography (n = 2), and CT hepatic arteriography (n = 1) was used. Using automatic image registration software (n = 20) and a manual segmentation technique (n = 4), fusion images were created in combination with post-RFA CT (equilibrium phase of intravenous CT).Automatic image registration and manual segmentation technique took approximately 2-3 and 5 minutes, respectively. Total time required for the creation of fusion images was less than 10 minutes in all cases. Fusion images enabled easier understanding of the relationship between the tumor and ablation zone, helping judge whether an ablative margin was ensured.Fusion of pre- and post-RFA CT images is considered a feasible tool in the evaluation of RFA therapy for HCC.

We report two cases in which volume subtraction three-dimensional CT angiography (VS-3DCTA) was used for cerebral aneurysm and vascular stenosis with intramural calcification. Case 1: VS-3DCTA with volume rendering clearly showed carotid cave aneurysm of the internal carotid artery. The location and size of the aneurysm was confirmed by digital subtraction angiography (DSA). In evaluation of the aneurysm, VS-3DCTA was equal to DSA and endovascular findings. Case 2: VS-3DCTA with volume rendering clearly showed stenosis of the middle cerebral artery, and intramural calcification with the cause of the stenosis was subtracted. On the other hand, it was difficult for DSA to reveal the stenosis because of the limitation of the imaging angle. In evaluation of the stenosis, VS-3DCTA was superior to DSA. VS-3DCTA was an important diagnostic tool that enabled visualization of the aneurysm in the area of the skull base and stenosis of the intracerebral artery.

High reproducibility of coronary artery calcium (CAC) scoring is a key requirement for monitoring the progression of coronary atherosclerosis. The purposes of this study were to compare electron beam CT and 16-MDCT scanners in the variability of repeated CAC measurements and to assess the factors influencing this variability.CAC models of different sizes attached to a cardiac phantom with a programmable variable heart rate were scanned three times, and interscan variability of the CAC measurement was calculated each time. For helical CT, different slice-thickness images of either retrospective ECG-gated or prospective ECG-triggering reconstruction were obtained. The detection of small amounts of calcium, variability of the Agatston score, and CAC measurement algorithms (Agatston, volume, and mass scores) were compared between CT scanners and protocols.All 1-mm-sized calcium models were detected on 0.625- and 1.25-mm helical CT, whereas some were missed on electron beam CT and 2.5-mm helical CT. Retrospective ECG-gated thin-slice helical CT showed the lowest variability. Reduction of variability by volume and mass scoring algorithms was less effective on 0.625- and 1.25-mm-thickness CT.Retrospective ECG-gated thin-slice helical CT has the potential to be a useful tool for monitoring coronary atherosclerosis.

Objective: The purpose of this study is to investigate how accurately we can measure CAC volume using electron beam computed tomography (CT) and 16-slice spiral CT. Materials and Methods: CAC models with known volume attached to a cardiac phantom were scanned. The error of measurement, variability between measured and real volumes and inter-scan measurement variability were obtained. For spiral CT, 7 different parameters; i.e. (1) slice-thickness (0.625mm, 1.25mm and 2.5mm), (2) retrospective spiral electrocardiograph (ECG)-gated or prospective axial ECG-triggering, (3) overlapping or non-overlapping, were included. Results: The error of measurement was 150n electron beam CT and 8-2027777735740n spiral CT. CAC volumes were underestimated in 92-0x1.4b3a0b6a4aap-149nd overestimated in 81024570420f the electron beam CT scans. Volumes were underestimated in 79%, correct in 5-0x1.86278bfffa1a8p-150nd overestimated in 1626651131640f the spiral CT scans. The best measurement and the least variability was observed on 0.625mm retrospective spiral ECG-gated CT (error of 8%), a significant result (t-test: p

Background Portal vein reconstruction is still a crucial problem in living-donor liver transplantation. Vascular closure staples (VCS) have been applied for small peripheral and large vessels because of the technical ease with which they can be employed. We describe here our experience with portal vein reconstruction in living donor-liver transplantation and compare VCS with conventional sutures in portal vein reconstruction. Methods The anastomosis between the donor portal vein and recipient portal vein or the right external iliac vein graft was created using either VCS or conventional sutures. Results The stenotic ratios were .51 ± .15 and .79 ± .25 for the conventional sutures and VCS, respectively. The stenotic ratio was significantly lower in VCS compared with conventional sutures. Conclusions VCS compared with conventional sutures has the advantage of low risk of anastomotic stenosis.

In the treatment of trigeminal neuralgia, Gasserian block under fluoroscopical guidance may be difficult because of anatomic variability, and difficulty in identification of the foramen ovale. We introduce how to use three-dimensional CT in the preprocedural planning. We determine the skull-rotation angle in which the foramen ovale is best visualized, the relationship (distance, angle) between the virtual puncture point and anatomical landmarks, and the distance between the virtual puncture point and the foramen.

The purpose of the present study was to evaluate the usefulness of a new gray-scale test pattern (NGTP) that was developed to easily adjust the gradients of thoracic CT imaging and enable visual consistency. The Society of Motion Picture and Television Engineers (SMPTE) pattern and the NGTP were used for comparison. The luminance character of two test patterns was evaluated by a luminance meter with three different window widths and levels (for default, mediastinum and lung). We also investigated whether SMPTE or NGTP is more suitable for adjusting the gradient of thoracic CT imaging. We found that it was easier to adjust the gradient of thoracic CT imaging with NGTP than with SMPTE, because the digital range of NGTP is 12 bits (the value of 4,096 HU, from -1,024 to 3,071 HU), and adjustable in any window width. We were able to adjust the gradients of hard-copy and soft-copy thoracic CT imaging within several hours using NGTP. We propose that NGTP is the most suitable tool for adjusting the gradients of thoracic CT imaging. NGTP can cope with any medical diagnostic display system connected with CT or MRI equipment in a network because it is in DICOM format.