Search

Relativistic and nonrelativistic Compton profile cross sections for H, C, N, O, P, and Ca and for a few important biological materials such as water, polyethylene, lucite, polystyrene, nylon, polycarbonate, bakelite, fat, bone and calcium hydroxyapatite are estimated for a number of Kα x-ray energies and for 59.54 keV (Am-241) γ photons. Energy broadening and geometrical broadening (ΔG) is estimated by assuming θmin and θmax are symmetrically situated around θ=90°. FWHM of J(PZ) and FWHM of Compton energy broadening are evaluated at various incident photon energies. These values are estimated around the centroid of the Compton profile with an energy interval of 0.1 and 1.0 keV for 59.54 keV photons. Total Compton, individual shell, and Compton energy–absorption scattering cross sections are evaluated in the energy region from 0.005 to 0.5 MeV. It is an attempt to know the effect of Doppler broadening for single atoms, many of which constitute the biological materials.

application/pdf, Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

Microtomographic images of rat's lumbar vertebra of different age groups varying from 8, 56 and 78 weeks were obtained at 30 keV using synchrotron X-rays with a spatial resolution of 12 μm . The images are analyzed in terms of 3D visualization and micro-architecture. Density histogram of rat's lumbar vertebra is compared with test phantoms. Rat's lumbar volume and phantom volume are studied at different concentrations of hydroxyapatite with slice number. With the use of 2D slices, 3D images are reconstructed, in order to know the evolution and a state of decline of bone microstructure with aging. Cross-sectional μ-CT images shows that the bone of young rat has a fine trabecular microstructure while that of the old rat has large meshed structure.

A phase-contrast X-ray imaging system—with a 60×30 mm field of view—for biomedical observations was developed. To extend the observation field of view, the system is fitted with a skew-symmetric two-crystal X-ray interferometer. To attain the required sub-nanoradian mechanical stability between the crystal blocks for precise operation, the interferometer was mounted on two extremely rigid positioning tables (one with a sleeve bearings) and was controlled by a feedback positioning system using phase-lock interferometry. The imaging system produced a 60×30 mm interference pattern with 60% visibility using 17.7 keV monochromatic synchrotron X-rays at the Photon Factory. It was then used to perform radiographic observation (i.e., phase mapping) of rat liver vessels. These results indicate that this imaging system can be used to perform observations of large and in vivo biological samples.

In the 15th Nationwide follow-up survey of primary liver cancer, 18,843 newly registered patients (1998-1999) and 18,405 follow-up patients from 791 hospitals in Japan were analyzed. Of the newly registered patients, approximately 95% were patients with hepatocellular carcinoma (HCC) and 3.3% had intrahepatic cholangiocarcinoma (ICC). The patients were assessed using 194 items that were related to epidemiological and clinicopathological factors, diagnosis, and treatment. Furthermore, the survival rates of all of the newly registered patients in the 10th-15th follow-up survey were calculated for each histological type, background factor(s) and treatment, respectively. In patients with hepatocellular carcinoma, the survival rates of patients who underwent hepatectomy, ethanol injection therapy, microwave coagulation therapy, or transcatheter arterial embolization were calculated by tumor size, tumor number, and clinical stage. This follow-up survey will be helpful to assess the progress of research and medical practice in the treatment of primary liver cancer.

Objective: The purpose of this study was to investigate the muscle recruitment variations in the dynamic ankle plantar flexion. Design: A total of 17 subjects participated in this study and performed the ankle plantar flexion exercise. Magnetic resonance T2-weighted images were obtained from the calf before and immediately after exercise to calculate each T2 relaxation time in the medial and lateral gastrocnemius, soleus, tibialis posterior, flexor digitorum/hallucis longus, peroneus longus, and dorsiflexors. Results: All the muscles except the dorsiflexors showed significantly increased T2 relaxation time and signal intensity on T2-weighted images after exercise. Above all, both gastrocnemius muscles showed significantly greater postexercise T2 relaxation time than the soleus, tibialis posterior, flexor digitorum/hallucis longus, and dorsiflexors. In addition, the peroneus longus had a tendency to show the greatest T2 relaxation time next to the gastrocnemius, but there was no significant difference between them. Conclusions: The present study may suggest that the gastrocnemius muscle, especially the medial side, was best recruited in the dynamic ankle plantar flexion exercise. In addition, it is possible that the peroneus longus was most recruited next to the gastrocnemius in this exercise mode.

Purpose: To investigate the effects of cooling human skeletal muscle after strenuous exercise using 31 P MR spectroscopy and MR imaging. Methods: 14 male subjects (mean age ± SD, 23.8 ± 2.3 yr) were randomly assigned to the normal (N = 7) or the cooling group (N = 7). All subjects performed the ankle plantar flexion exercise (12 repetitions, 5 sets). Localized 31 P-spectra were collected from the medial gastrocnemius before and after exercise (immediately, 30, 60 min, 24, 48, 96, and 168 h) to determine the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular pH. Transaxial T2-weighted MR images of the medial gastrocnemius were obtained to calculate T2 relaxation time (T2), indicative of intramuscular water level, before and after exercise (24, 48, 96, and 168 h). In addition, the muscle soreness level was assessed at the same time as 31 P-spectra measurements. Fifteen-minute cold-water immersion was administered to the cooling group after exercise and initial postexercise measurements. Results: The control group showed significantly increased T2 from rest at 48 h after exercise (P < 0.05), but the cooling group showed no significant change in T2 throughout this study. Both groups showed a significantly decreased intracellular pH immediately after exercise (P < 0.05). After that, the cooling group showed a significantly greater value than the value at rest or the control group at 60 min after exercise (P < 0.05). For the Pi/PCr, no significant change was observed in both groups throughout this study. The muscle soreness level significantly increased immediately and at 24-48 h after exercise in both groups (P < 0.05). Conclusion: The findings of this study suggest that cooling causes an increase in intracellular pH and prevents the delayed muscle edema.

Purpose To compare two fat suppression techniques of spectrally-selective inversion pulse (spectral presaturation with inversion recovery—SPIR) and spectral-spatial excitation pulse of water excitation (WE) for contrast-enhanced MR imaging of the breast. Materials and Methods Forty women with histologically-proven breast cancer were examined. Both pulse types were applied to postcontrast, axial, three-dimensional field echo sequence. Contrast noise ratios (CNR) of lesion-to-breast parenchyma, lesion-to-fat, and parenchyma-to-fat were determined. Qualitative image analysis using a four-point scale was also performed by two observers. Results All the CNR values of obtained with WE techniques were significantly higher than those with SPIR. Qualitative analysis indicated that the WE images were statistically superior for the lesion-to-breast parenchyma contrast while being slightly inferior to the SPIR images for fat suppression homogeneity without statistical significance. Conclusion Compared to SPIR, the WE technique suppressed the subcutaneous fat signal more potently and improved the contrast of the enhanced breast lesion against the parenchyma and the subcutaneous fat. WE will be a powerful fat suppression strategy for enhanced MR imaging of the breast. J. Magn. Reson. Imaging 2003;18:310–314. © 2003 Wiley-Liss, Inc.

Thickened or indistinct junctional zone (JZ) is a problematic finding in staging endometrial carcinoma. We studied the incidence, pathological cause of this condition correlated to microcirculation, and the utility of dynamic contrast MRI for differential diagnosis. T2-weighted images were analyzed in 119 cases with endometrial carcinoma. The enhancement of the JZ during the dynamic contrast MRI, histopathological causes, and the density of arterioles in the JZ were retrospectively analyzed in cases with thickened or indistinct JZ. The MRI histopathological correlation of all 31 patients with a thickened or indistinct JZ were analyzed, in which it was corresponded to myometrial cancer invasion only in 22%. The sensitivity of a poor early enhancement pattern on dynamic study for detecting myometrial invasion was 71.4%, the specificity was 100%, and the overall accuracy was 92.5%. Although only weak relationship between the contrast enhancement and the arteriole density was revealed, the arteriole density within the JZ with cancer invasion was significantly decreased. Poor enhancement of JZ in early dynamic phase was correlated with the decreased density of arterioles within the myometrium which was invaded by endometrial carcinoma. Dynamic contrast study should be performed in staging endometrial carcinoma especially when JZ was thickened or indistinct.

A 36-year-old woman with tears of the anterior cruciate ligament and medial meniscus received a meniscectomy. The MR images obtained prior to the partial meniscectomy showed a bucket-handle meniscal tear with centrally displaced fragment lying anterior to the posterior cruciate ligament (PCL), representing a "double PCL sign"; however, after the meniscectomy, MR images demonstrated a fragment in the space posterior to the PCL where no structure is generally recognized except for the ligament of Wrisberg. This article reports a "reversed" double PCL sign, caused by inadequate surgical clearance of a bucket-handle tear of the medial meniscus.

Magnetic resonance (MR) imaging is useful not only for preoperative staging of gynecologic malignancies but also for prediction of the histopathologic features of a variety of intrapelvic tumors. Familiarity with the specific imaging findings that have been reported for the uterine cervix is a goal of radiologists. The typical MR imaging findings of uterine cervical lesions correspond to the histopathologic features. These lesions can be categorized as epithelial neoplasms, nonepithelial neoplasms, and nonneoplastic diseases. Cervical carcinoma accounts for most cases of malignant lesions and is staged by using the classification system established by the International Federation of Gynecology and Obstetrics. MR imaging allows differentiation between endophytic and exophytic growth and between normal and abnormal findings after hysterectomy and irradiation. Other epithelial neoplasms of the uterine cervix include adenoma malignum, which is a special type of cervical adenocarcinoma, as well as carcinoid tumor and malignant melanoma. Nonepithelial neoplasms of the uterine cervix include malignant lymphoma and leiomyoma. Nonneoplastic diseases of the uterine cervix include cervical pregnancy, cervicitis, nabothian cysts, polyps, and endometriosis.

Purpose: Lymph node metastasis is a major prognostic factor in the treatment of cervical cancer, but its nonsurgical assessment is not necessarily accurate, particularly in small nodes. We evaluated whether node-negative status could be accurately assessed using a low cutoff measure. Methods and Materials: The subjects were 84 patients with Stage IIB-IVA cervical squamous cell carcinoma treated by definitive radiotherapy. Nodal status was assessed by CT as negative ( 10 mm). Cause-specific survival and the disease-free rate, including the pelvic recurrence-free and distant metastasis-free rates, were estimated. Results: The cause-specific survival, disease-free rate, and pelvic recurrence-free rate at 5 years were significantly higher for the 32 patients with node-negative disease (83.5%, 86.1%, and 86.1%) and the 17 patients with possibly node-positive disease (59.2%, 93.8%, and 93.8%) than for the 35 patients with probably node-positive disease (32.6%, 22.0%, and 46.8%), respectively. No significant difference was found between negative and possibly node-positive status. In contrast, the distant metastasis-free rate differed significantly among node-negative (96.4%), possibly node-positive (59.3%), and probably node-positive (35.1%) status. Conclusion: Node-negative status assessed using a strict cutoff measure may be useful as a strong predictor of cervical cancer being confined to the pelvis.

The present study was designed to evaluate the use of a 1.0T portable permanent magnet MR system in obtaining microscopic MR images of the hyaline cartilage in vitro. A clear laminar appearance was demonstrated with this system. In addition, it was possible to demonstrate cartilage surface irregularity, a decrease in cartilage thickness, and T2 alteration by proteoglycan depletion following up to 12 hours of trypsin treatment. In summary, the portable MR system is useful for investigating cartilage in vitro.

The most common location of intracranial epidermoid is the cerebellopontine angle (CPA). The present study compared the visibility of epidermoid at the CPA in various pulse sequences. Seven patients with epidermoid at the CPA underwent conventional MR imaging (T(1)-, T(2)- and proton density-weighted imaging) as well as diffusion-weighted echo-planar imaging. Fast fluid-attenuated inversion recovery (FLAIR) sequences, magnetization transfer contrast (MTC) sequences, and MR cisternography were employed for selected patients. The signal intensity of the lesions relative to cerebrospinal fluid (CSF), the degree of lesion demarcation and the displacement of surrounding structures were evaluated. Proton density-weighted imaging depicted the lesions as hyper-intense to CSF with clearer delineation than T(1)- and T(2)-weighted imaging. Diffusion-weighted imaging depicted all lesions as strongly hyper-intense relative to CSF and brain tissue. FLAIR sequences depicted the lesions with mixed signal intensities but with poor-to-medium demarcation. MTC imaging increased delineation of the lesions to some degree. MR cisternography depicted the lesions as hypo-intense to CSF and clearly showed the anatomical relation to neighboring nerves and vessels. We concluded that diffusion-weighted imaging could specifically reveal an epidermoid at the CPA as a strongly hyper-intense lesion, and that MR cisternography is mandatory for preoperative planning.

Computed tomographic images of soft materials are obtained using differential attenuation and transmission method with a tube source of X-rays, for samples like walnut, brew tooth and peaches in order to know the interior properties of the material at optimum energy in terms of attenuation coefficient. At optimum energy it is possible to calculate the three-dimensional representation of inner and outer surfaces of the object. The interior of the soft material is visualized using the novel soft ware in order to know the distribution of attenuation coefficient in terms of density. The results for walnut, brew tooth and peaches are presented as a set of images from the internal parts of the sample.

OBJECTIVE: To investigate the possibility of objective clinical assessment of the radioresponse of cervical cancer via determination of serum squamous cell carcinoma antigen levels and magnetic resonance imaging (MRI)-based estimation of tumor shrinkage. METHODS: The cases of 60 patients undergoing definitive radiotherapy for cervical squamous cell carcinoma (stage I–II: n = 20; stage III–IV: n = 40) were reviewed. Measurements of serum squamous cell carcinoma antigen levels (n = 60), estimated tumor volume on preradiotherapy MRIs (n = 60), and evaluated tumor shrinkage on postradiotherapy MRIs available (n = 30) were taken. The relation between postradiotherapy squamous cell carcinoma antigen level 2 months after the start of radiotherapy and disease recurrence was investigated. Regression analysis of tumor volume measured on MRIs was used to estimate the extent of tumor shrinkage 2 months after the start of radiotherapy. RESULTS: Preradiotherapy squamous cell carcinoma antigen levels correlated significantly with preradiotherapy tumor volumes. Recurrence was identified in 27 patients as distant (n = 19), distant and local (n = 1), local (n = 5), or regional (n = 2). Of 51 patients with elevated preradiotherapy squamous cell carcinoma antigen levels, 33 achieved normalized levels after radiotherapy. Squamous cell carcinoma antigen normalization was associated with a higher recurrence-free survival rate at 2 years (74.3%) than that associated with nonnormalization of squamous cell carcinoma antigen (5.6%, P < .001). The extent of shrinkage ranged from 61% to 100%, and there was no local recurrence. CONCLUSION: Postradiotherapy squamous cell carcinoma antigen status is a useful indicator of clinical outcome, particularly about tumor recurrence. It is not, however, useful for assessing response to radiotherapy. Magnetic resonance imaging is useful for obtaining an objective assessment of radioresponse.

Objective. To evaluate MR microscopic images of normal-appearing porcine hyaline cartilage (n=15) in vitro obtained with an MR microscope using an independent console system (MRMICS) at 1.5 T. Design and results. The MRMICS is a portable imaging system consisting of a radiofrequency system, gradient power supplies and a personal computer. The images from the MRMICS showed a laminar structure of porcine cartilage similar to the structure demonstrated with other MR imaging techniques. The laminar structures of the articular cartilage, were, however heterogeneous in respect of signal intensity and thickness, which varied according to the site resected. The MR laminar appearance was most comparable to the staining with Masson's trichrome for collagen. Conclusion. MRMICS is a useful add-on system for obtaining microscopic MR images of articular cartilage in vitro.

Large-area (25 x 20 mm) phase-contrast X-ray imaging was attained by using a skew-symmetric two-crystal X-ray interferometer. The sub-nrad angular control required to operate the X-ray interferometer was achieved with a sleeve bearing and a feedback-positioning system. As a demonstration, measurements of a phase map of a rat's liver and a phase-contrast tomographic three-dimensional image of a piece of a rabbit's liver were performed at the Photon Factory using 0.07 nm synchrotron radiation X-rays.

Purpose To investigate the efficacy of SENSE MRI, including the double arterial phase dynamic study, to detect hypervascular hepatocellular carcinomas (HCCs). Materials and Methods MRI of the liver was performed in 40 consecutive patients (20 by conventional MRI and 20 by SENSE MRI). The SENSE technique was used to obtain breath-hold T1-weighted FSE images (TR/TE = 556/12 msec), respiratory-triggered T2-weighted FSE images (TR/TE = 1800/90 msec) with and without fat suppression, and dynamic MR images (TR/TE/FA = 160–168/4.6 msec/70°). In each arterial dominant phase and portal dominant phase, two scans were consecutively performed with one breath-hold, leading to the double arterial phase and double portal phase images with SENSE. Results The sensitivity of SENSE MRI for HCCs diagnosed from all MR images, including dynamic study, T1-weighted images, and T2-weighted images, was 91.7%, while that of conventional MRI was 76.3%. The positive predictive value of SENSE MRI for HCCs was 91.7%, while that of conventional MRI was 87.9%. In terms of HCCs ≤ 10 mm, the sensitivity and positive predictive values of SENSE MRI were 78.6% and 78.6%, respectively, while those of conventional MRI were 27.3% and 60.0%, respectively. The number of detected HCCs ≤ 10 mm was significantly larger in SENSE MRI than in conventional MRI (P < 0.05). The cause of false-positive lesions on SENSE MR images was an arterioportal shunt. Conclusion SENSE MRI with double arterial phase dynamic study showed higher sensitivity compared to the conventional technique. Therefore, SENSE MRI is a promising method for the detection of HCC. J. Magn. Reson. Imaging 2002;16:259–266. © 2002 Wiley-Liss, Inc.

Compton, Rayleigh and fluorescence cross-sections for low, medium and high Z atoms are measured at low photon energies (

We studied chronological magnetic resonance spectral changes in brain abscesses before and after medical and/or surgical treatment. We examined five patients with MRI imaging and (1)H magnetic resonance spectroscopy (MRS) on two or more occasions, using two volume-of-interest patterns, and saw chronological changes related to the evolution of the abscess. A spectrum specific for brain abscess was found in three of the five cases, while two showed a single lactate peak in the first study. In two cases, phenylalanine or alanine appeared in the second study. We observed the disappearance of the specific spectra and a single lactate peak following surgery. Only one patient showed different spectra in different volume of interest.

The authors reported two cases with ovarian tumors with functioning stroma. One was an ovarian carcinoid with testosterone-producing stroma and another was an ovarian mucinous cystadenoma with elevated serum level of estrogen. They appeared as multilocular cystic masses with varying signal on MR. This imaging feature was mimicking both those of Sertoli-Leydig tumors with heterologous elements and granulosa cell tumors, which are well known as functioning tumors. It had been reported in pathological literatures that any type of ovarian tumors can show hormonal activity due to functional stroma, although, it is the first report in the radiological literatures.

Localized, abnormal attenuation/intensity areas on unenhanced and/or enhanced study of CT/MR imaging do not necessarily correspond to tumors themselves or real tumor size. Pitfalls in the diagnosis of liver tumor are described dividing into enhanced study (vascular variants, vascular abnormalities, hyperplastic nodules, around the tumor, and miscellaneous) and unenhanced study (fatty change, focal spared area of diffuse fatty liver, and miscellaneous).

SUMMARY Improving the speed of fluorescent X-ray CT imag-ing using synchrotron radiation has been studied from thepoints of view of the imaging system and the processingalgorithm. Regarding the imaging system, high-speed im-aging at 2 seconds per point with a dead time of about 6%has been realized by incorporating an electronic systemwhich operates stably in the high count rate region. Inaddition, the amounts of computation and memory requiredhave been reduced to about 1/100 of the levels realized upto now by improving the efficiency of the reconstructionalgorithm. The quantitative properties of this system havebeen confirmed by tests with a physical phantom and theiodine distribution has been estimated in in vitro humanthyroid images. These results indicate the implementabilityof in vivo fluorescent X-ray CT instrumentation. ' 2002Scripta Technica, Syst Comp Jpn, 33(2): 1Œ11, 2002; DOI10.1002/scj.1101Key words: Fluorescent X-ray; CT (computed to-mography); synchrotron radiation; image reconstruction.

The authors reported a case of fundal-type adenomyomatosis in which mural stratification corresponding to histopathological findings was clearly demonstrated with MR imaging. Single-shot fast spin echo images for MR cholangiopancreatography clearly visualized Rokitansky-Aschoff sinuses (RAS), which are a diagnostic clue for this disease. However, mural stratification comprising RAS with muscular proliferation, massive fibrosis and subserosal fat deposition was more precisely demonstrated in T(2)-weighted images obtained with fast spin echo.

Background: To define radiographically simple prolapse or intussusception in cases of distal migration of duodenal tumors. Methods: In one pyloric and four duodenal tumors showing distal migration, the findings of gastrointestinal contrast examinations were retrospectively evaluated in relation to CT and operative findings. Results: All lesions were intraluminal growing and well demarcated, and they included two carcinoids, a papillary adenoma, a Brunner's gland adenoma, and a hyperplastic polyp. All lesions were accompanied by long mucosal stalks, and, in three, folding deformity of the proximal jejunum was observed. CT showed no target signs except for one with gastroduodenal intussusception. Intussusception was not verified surgically in any cases. Conclusion: Distal migration of duodenal tumors can occur as the result of mucosal elongation and slipping. Duodenojejunal intussusception is not necessarily associated with that phenomenon.

PURPOSE To estimate the effects of a lead plate, three types of needle holders, tube current, and slice thickness on decreasing the radiation dose to the physician's hand during interventional procedures with computed tomographic (CT) fluoroscopic guidance. The needle holders (I-I devices), which were developed by the authors, maintained the distance between the physician's hand and the CT plane at 7 cm, 10 cm, and 15 cm, respectively. MATERIALS AND METHODS The dose rate (mSv/tube current/CT fluoroscopy time) was measured in 55 cases, which were divided into six groups. In group A ( n = 14), the current was 135 kV, there was a 5-mm slice thickness, and a 7-cm I-I device was used without the lead plate. Group B ( n = 11) entailed a 120-kV current, a 5-mm slice thickness, and a 7-cm I-I device without the lead plate. Group C ( n = 8) entailed a 120-kV current, 5-mm slice thickness, and 7-cm I-I device with the lead plate. Group D ( n = 9) entailed a 120-kV current, 5-mm slice thickness, and 10-cm I-I device with the lead plate. Group E ( n = 7) entailed a 120-kV current, 5-mm slice thickness, and 15-cm I-I device with the lead plate. Group F ( n = 6) entailed a 120-kV current, 1-mm slice thickness and 10-cm I-I device with the lead plate. To compare the effects of tube voltage, lead plate use, slice collimation, and I-I devices, differences were compared between groups A and B, B and C, D and F, and among groups C, D, and E. RESULTS The dose rates of groups A, B, C, D, E, and F were 126.3, 75.2, 17.8, 13.9, 2.8, and 4.1 mSv/mA/sec × 100,000, respectively. There were significant differences in dose rates between groups A and B ( t -test, P = .037), B and C (Student t -test, P = .002), D and F (Mann-Whitney test, P = .011), and among groups C, D, and E (Kruskal-Wallis test, P = .016). CONCLUSION The lead plate, the improved I-I devices, use of a 120 kV (vs 135kV) current, and 1-mm (vs 5 mm) collimation were all useful in decreasing the dose rate.

Large X-ray interferometers are developed for phase-contrast X-ray imaging aiming at medical applications. A monolithic X-ray interferometer and a separate one are studied, and currently a 25 mm×20 mm view area can be generated. This paper describes the strategy of our research program and some recent developments.

Fluorescent X-ray computed tomography (FXCT) at a 0.05 mm in-plane spatial resolution and 0.05 mm slice thickness depicted the cross sectional distribution of endogenous iodine within thyroid. The distribution obtained from the FXCT image correlated closely to that obtained from the pathological pictures.

Using a monolithic X-ray interferometer having the view size of 25 mm×25 mm, phase-contrast X-ray CT (PCCT) was performed for non-formalin fixed livers of two normal rats and a rabbit transplanted with VX-2 cancer. PCCT images of liver and cancer lesions resembled well those obtained by formalin fixed samples.

Antenatal diagnosis of placenta accreta with MR is not easy even now because T2-weighted images (T2WI) cannot differentiate chorionic villi from decidua basalis. We performed dynamic contrast MRI to study whether trophoblastic villi could be separately demonstrated from the decidua basalis, and whether the contrast resolution between the placenta and myometrium could improve compared to T2WI. Six pregnant women with prior cesarean section were examined at 34-38 gestational weeks. Sagittal T2-weighted images with fast spin echo sequences and dynamic contrast studies with fast field echo sequence every 10-14 s after contrast injection were performed. We analyzed the enhancing pattern of the placenta and compared the contrast between placenta and myometrium. We reviewed medical records to identify complications during the placental delivery and the complications of their newborns. In the early phase after contrast enhancement, multiple foci of the strong lobular enhancement were observed in all cases. Other parts of placenta were slowly but strongly enhanced following them. We speculated that the former corresponded to intervillous space and the latter decidua basalis. The contrast between placenta and myometrium tended to be distinct near the inner cervical os on both T2WI and dynamic contrast study. On the other hand, it was indistinct in the upper part of the uterine body on T2WI despite it was clearly demonstrated on dynamic contrast study. The placentae were delivered without any complication in all cases. Although two neonates showed fetal distress, none of the infant remained any sequelae at the time of the discharge. The other four were well although one of them complicated with meconium staining. As dynamic contrast MRI can differentiate chorionic villi and decidua basalis, and can provide excellent contrast between placenta and myometrium at anywhere within the uterus, it may be a promising technique for antepartum diagnosis of the placenta accreta.

The aim was to study the influence of postsurgical gross residual tumor volume on local control of maxillary sinus cancer treated with radiotherapy combined with debulking surgery.Forty-three patients who underwent combined surgery and radiotherapy (50-72 Gy, median 60 Gy) for squamous cell carcinoma of the maxillary sinus were reviewed. Gross residual tumor volume (GRTV) after surgery was measured on computed tomograms obtained during the radiotherapy planning. Patients were classified according to GRTV as follows: group AA, GRTV = 0 (microscopic residual, n = 2); group A, GRTV10 cm3 (n = 24); group B, 10-40 cm3 (n = 9); and group C,or = 40 cm3 (n = 8). The relationship between local control and GRTV was analyzed using univariate and multivariate analysis.The 2-year local control rate for all patients was 62%. The differences in local control rates between groups AA, A and B were not significant (P0.05), but the rate was significantly lower in group C than in the other groups (69% at 2 years vs 31% at 1 year, P0.001). Multivariate analysis showed that GRTV (P = 0.002) and histological differentiation (poorly differentiated histology was favorable, P = 0.035) were independent prognostic factors and that intra-arterial chemotherapy and administered total dose were not. Local control in groups A and B significantly depended on the total dose of radiotherapy, with 2-year control rates of patients receiving 50 Gy (n = 6) andor = 60 Gy (n = 27) of 17% vs 79%, respectively (P0.001).Our data suggest that adequate, not complete, debulking associated with a total radiotherapy dose ofor = 60 Gy can provide satisfactory local control for patients with squamous cell carcinoma of the maxillary sinus.

PURPOSE To investigate the efficacy of computed tomography (CT) fluoroscopy and a new needle holder (the I-I device) in lung nodule biopsy. MATERIALS AND METHODS The I-I device is made of acrylate resin and was used to keep the entire needle in the tomographic plane. This study consisted of biopsies of 79 lung nodules in 77 patients. The final diagnoses were malignant in 54 patients, benign in 23, and unconfirmed in two. The biopsy procedure time from the beginning of the CT fluoroscopy procedure to the removal of the needle was measured for 24 needle passes. The radiation dose on the physician's hand was measured in five cases with use of a thermoluminescence ring. RESULTS Fifty-one malignant and 20 benign lesions were correctly diagnosed with histologic specimens (90%). In 58 of 77 patients (75%), the biopsy procedures were completed within a single breath-hold. Pneumothorax occurred in 20 of 77 patients (26%) and chest tube insertion was required in five. The incidence of pneumothorax was significantly lower in patients who held their breath during biopsy procedures compared with those who did not ( P 2 test). The biopsy procedure time ranged from 15 to 39 seconds (mean: 28.2 sec). The mean radiation dose on the physician's hand was 2 mSv/case. CONCLUSION The diagnostic accuracy of biopsy with use of the I-I device under CT fluoroscopic guidance is comparable with that of the conventional method; however, a combination of CT fluoroscopy and the I-I device enables rapid biopsy procedures.

Superparamagnetic iron oxide (SPIO)-enhanced MRI was performed in twenty-one patients undergoing proton-beam radiotherapy for hepatocellular carcinomas. Patients were divided into two groups: early and late phase hepatic injuries. Each group was investigated 3 to 9 weeks and 4 to 65 months after the start of irradiation, respectively. T(1)-weighted, T(2)-weighted, and T(2)*-weighted images were obtained before and after SPIO administration. In all postcontrast sequences in the early phase, irradiated livers demonstrated relatively higher intensity than nonirradiated livers and the radiation-to-liver contrast-to-noise ratio (C/N) was improved. Postcontrast T(2)*-weighted images showed the highest C/N. In the late phase, the irradiated areas showed high intensity on T(2)-weighted images and low intensity on T(1)-weighted images without SPIO, while high intensity on T(1)-weighted images with SPIO. The C/N increased with SPIO in all sequences and postcontrast T(2)-weighted images showed the highest C/N in the late phase. SPIO-enhanced MRI is useful to evaluate this entity both in the early and late phase of clinical studies.

The aim of this study was to obtain MR images in the flexed-knee position and to compare the diagnostic value to the extended position in delineation of the menisci. With a mobile knee brace and a flexible surface coil, the knee joint was either fully extended or bent to a semi-flexed position (average 45 degrees of flexion) within a 1.5-T superconducting magnet. Sets of sagittal MR images were obtained for both the extended- and flexed-knee positions. Using the arthroscopic results as gold standards, 97 menisci were evaluated. Two observers interpreted each MR image of the extended and flexed positions independently without knowledge of the arthroscopic results. Flexed-knee MR images revealed 22 of the 27 arthroscopically proven torn menisci and 69 of the 70 intact menisci, for a sensitivity of 81.5%, a specificity of 98.6%, and an accuracy of 93.8%. Extended-knee MR images indicated a sensitivity of 81.5%, a specificity of 92.9%, and an accuracy of 89.7%. No statistically significant difference was found between the two positions. To enhance MR visualization of all the knee components, we recommend examining the knee in a flexed position within the magnet.

Early radiation-induced liver injury during radiotherapy detected by a particulate reticuloendothelial MR contrast agent (superparamagnetic iron oxide; SPIO) is described in a patient with cholangiocarcinoma. The irradiated hepatic parenchyma appeared as a heterogeneous, less decreased signal intensity area than the nonirradiated area on MR images after SPIO administration. Resultant differences in signal intensity were better visualized on SPIO-enhanced T1-weighted images than SPIO-enhanced T2-weighted images, although SPIO-enhanced T2 * -weighted fast field echo imaging was the most sensitive.

Background. Magnetic resonance imaging (MRI) provides precise staging of endometrial carcinoma. However, we have sometimes experienced patients with microscopic extrauterine extension in whom MRI showed the disease as being limited to the uterus. We studied indirect MRI signs for microscopic extrauterine spread of endometrial carcinoma which outwardly seemed to be limited to within the uterus.

Purpose: To simulate drug distribution during balloon-occluded arterial chemotherapy infusion (BOAI) for urinary bladder cancer using subtraction computed tomography (CT) with low-flow-rate arterial contrast injection (S-CTLA). Methods: Ten patients with bladder cancer underwent S-CTLA, and the distribution of contrast agent during BOAI into both internal iliac arteries simultaneously was evaluated in nine pairs of internal iliac arteries and one single artery. For S-CTLA, spiral CT data were acquired before and after 0.2 ml/sec intraarterial injection of contrast material. The enhancement of the urinary bladder wall, the gluteal muscles, and the pelvic bones was categorized using a 4-grade scale. The grades were compared in each of the three pelvic components and differences were tested for significance using the Wilcoxon test for paired groups. Results: S-CTLA revealed the distribution of the contrast agent clearly. Gluteal muscles grades were significantly higher than those of the other two assessed components. Conclusion: BOAI does not improve the concentration of contrast agent to the bladder wall over neighboring structures, suggesting that the balloon occlusion technique does not achieve its desired goal for chemotherapy targeting.

The purpose of this study was to analyze magnetic resonance (MR) images of radiation osteitis of sacroiliac joints, retrospectively. Seven patients with radiation osteitis, which was diagnosed by pelvic plain radiographs and CT images, underwent MRI. T(1)-weighted spin echo images and T(2)-weighted fast spin echo images were obtained in all patients. Four patients were examined after gadolinium injection. Major signal changes of radiation osteitis were distributed on the iliac side. T(1)-weighted images showed diffuse low intensity both in sacral and iliac sides. T(2)-weighted images showed very low intensity adjacent to sacroiliac joints, but mixed intensity was illustrated apart from joints, and high intensity in the peripheral areas. Radiation osteitis showed slight to mild, but irregular enhancement in four patients after gadolinium administration. MRI can illustrate abnormal bone change distribution and is useful for diagnosing this entity by characteristic intensity patterns on T(1)-weighted images with and without gadolinium and T(2)-weighted image. However, the diagnosis of accompanied insufficiency fractures in the area of radiation osteitis is occasionally difficult with conventional MRI.

Purpose: To examine the practical feasibility of using a 3.0-T MR unit to obtain high-quality, high-resolution images of the knee joint. Material and Methods: One human cadaveric and 5 porcine knees were imaged with the 3.0-T unit. Sets of T1-weighted spin echo images were obtained with in-plane resolution of 0.195 × 0.39 mm and an acquisition time of approximately 5 min. Two porcine knees were also imaged with the 1.0-T unit with an identical imaging protocol and the signal-to-noise (S/N) ratios were measured on images at 3 T and 1 T. Results: The 3-T MR system provided detailed delineation of the knees. Deep layers of the medial collateral ligament and associated fine fibers beneath the medial and lateral collateral ligament were demarcated. We observed precise demonstration of the tibial attachment of the anterior cruciate ligament, irregularity of the meniscal free edge, and conjoint tendon formation together with the lateral collateral ligament and the biceps femoris tendon. Compared to the 1-T unit, the S/N ratio with the 3-T unit was increased by a factor of 1.39 to 1.72. Conclusion: Due to the potential advantage of obtaining detailed images, the 3-T MR system suggests a practical utility for fine demonstration of the knee morphology.

Aiming at large-area phase-contrast x-ray imaging, a separated-type x-ray interferometer system was designed and developed to produce 25×20 mm interference patterns. The skew-symmetric optical system was adopted because of the feasibility of alignment. The rotation between the separated crystal blocks was controlled within a drift of 0.06 nrad using a feedback positioning system. This interferometer generated a 25×15 mm interference pattern with 0.07 nm synchrotron x-rays. A slice of a rabbit’s kidney was observed, and its tubular structure could be revealed in a measured phase map.

Two-dimensional digital mammography with synchrotron radiation was developed to obtain high-contrast images. The system consisted of a single-crystal monochromator with an asymmetrically reflecting silicon 〈311〉 crystal, an avalanche multiplication-type pick-up tube camera with a fluorescent plate and lens-coupling system, and a workstation. The preliminary experiment was carried out with a synchrotron light source at the Photon Factory, KEK, in Tsukuba. Breast phantom and human breast specimen were imaged using 20 keV monochromatic synchrotron X-rays. These images were compared with images obtained by a conventional mammography system. The minimal detectable diameter of microcalcification on the breast phantom was 165 µm by the two-dimensional synchrotron radiation imaging system and 196 µm by the conventional mammography system. In the breast specimens, microcalcification and soft-tissue masses were clearly imaged and their contrasts improved by about 18% and 38%, respectively, in the two-dimensional synchrotron radiation system. The entrance surface dose of the two-dimensional synchrotron radiation system was about 400 mR, which was almost the same value as the 420 mR delivered by the conventional mammography system. Two-dimensional synchrotron radiation digital mammography is considered to be a powerful imaging modality for diagnosing breast tumors.

Purpose The purpose of this study was to investigate the long-term imaging appearances of hepatic injury following proton beam irradiation. The time-attenuation curves, time of appearance and recovery, and 3D size reduction pattern are described in patients of different ages and genders with different irradiation doses, irradiated portals, and Child groups. Method Forty-six patients with hepatocellular carcinoma underwent 50 to 84 Gy proton beam irradiation in periods of 14-52 days. CT including noncontrast and dynamic study was performed every 3 months starting 3 weeks after the end of irradiation. The 3D volume measurement of areas of radiation-induced hepatic injury was performed through incremental dynamic CT images in every follow-up study. CT follow-up study of the patients was done for 12-76 months. Results Radiation-induced hepatic injury was observed as low attenuation areas on noncontrast CT and enhanced areas on dynamic study in the regions corresponding to the irradiation portals. Of our cases, 67.5% showed the appearance of radiation hepatitis in 3-4 weeks and 95.3% in 3-4 months after the end of irradiation. In both periods, there was a significant delay in the female patients. The time-attenuation curve showed an early and prolonged enhancement of the irradiated regions. The volume reduction pattern of the injured areas was found to be longstanding, exponential, and directed from periphery to the center. Conclusion Early appearance of radiation-induced hepatic injury was found only to be gender dependent, with a tendency to occur with higher irradiated doses; no other parameters affected this phenomenon in our cases. Disappearance of the injured areas, if present, takes a long time (at least 42 months).

B. I. Choi, J. W. Chung, Y. Itai, O. Matsui, J. K. Han, M. C. Han 1 Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine 28, Yongon-Dong, Chongno-Gu, Seoul, 110-744, Korea 2 Institute of Clinical Medicine University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305, Japan 3 Department of Radiology, Kanazawa University School of Medicine, 13-1 Takaramachi, Kanazawa 920, Japan

Background To investigate nontumorous focal enhancement (FE) with computed tomographic hepatic arteriography (CTHA) and perfusion defect (PD) with computed tomographic arterial portography (CTAP) in pericystic liver tissue. Methods Incidence, shape, and size of nontumorous FE on CTHA and PD on CTAP were examined in 100 consecutive noncirrhotic and 100 consecutive cirrhotic patients. Results FE was observed on CTHA in 77 noncirrhotic and 61 cirrhotic patients, whereas PD was observed on CTAP in 50 noncirrhotic and 51 cirrhotic patients. When both findings were visualized in both CT studies, the shape of the FE on CTHA was similar to the overlapping PD on CTAP in 81% of patients but was larger in 92% of patients. Conclusions FE on CTHA and PD on CTAP are frequently noted in pericystic liver tissue. The size of FE on CTHA is often larger than PD on CTAP, although the shapes are generally the same. Size discrepancy suggests the presence of both portal supply and splanchnic venous drainage.

Although multilocular cystic gynaecological masses in which the loculi show variable signal intensity on both T1 and T2 weighted images have been considered to be mucinous cystadenoma or adenocarcinoma, other gynaecological tumours can demonstrate this "stained glass" appearance. These include mature cystic teratoma, fibrothecoma, endometrioma, Brenner's tumour of the ovary and degenerated leiomyoma of the uterus, all of which may mimic mucinous tumours of the ovaries.