[en] Phase contrast MR angiography (PC-MRA) depends on phase shifts caused by blood flow. Generally, PC sequences employ one VENC (velocity-encoding) value for each encoded spatial direction to optimize the signal in major vessels during peak systolic flow. We compared a mono-(30) with a multi-(20/30/45) VENC-PC-MRA technique in 10 patients with peripheral arterial occlusive disease. In all patients, the multi-VENC-PC sequence enhanced the vascular signal in vessels with very different flow velocities in one measurement. Large fields-of-view can be measured in a relatively short examination time to obtain an overview of the peripheral arterial system of the patient when contrast-enhanced MRA is not possible

[en] Purpose: Automated methods for the detection of pulmonary nodules and nodule volume calculation on CT are described. Material and Methods: Gray-level threshold methods were used to segment the thorax from the background and then the lung parenchyma from the thoracic wall and mediastinum. A deformable model was applied to segment the lung boundaries, and the segmentation results were compared with the thresholding method. The lesions that had high gray values were extracted from the segmented lung parenchyma. The selected lesions included nodules, blood vessels and partial volume effects. The discriminating features such as size, solid shape, average, standard deviation and correlation coefficient of selected lesions were used to distinguish true nodules from pseudo lesions. With texture features of true nodules, the contour-following method, which tracks the segmented lung boundaries, was applied to detect juxtapleural nodules that were contiguous to the pleural surface. Volume and circularity calculations were performed for each identified nodule. The identified nodules were sorted in descending order of volume. These methods were applied to 827 image slices of 24 cases. Results: Computer-aided diagnosis gave a nodule detection sensitivity of 96% and no false-positive findings. Conclusion: The computer-aided diagnosis scheme was useful for pulmonary nodule detection and gave characteristics of detected nodules

[en] Purpose: Multidetector-row CT is a new technology with a short scanning time. Multislice dynamic CT (MSDCT) in various directions can be obtained using the multidetector-row CT with multiplanar reformatting (MPR) technique. Material and Methods: We evaluated the initial results of sagittal and coronal MSDCT images reconstructed by MPR (MSDCT-MPR) in 3 pituitary adenoma patients with a pacemaker. Results: In a patient with microadenoma, the maximum contrast between the normal anterior pituitary gland and the adenoma occurred approximately 50 s after the start of the contrast medium injection. A microadenoma was depicted as a less enhanced area relative to normal pituitary tissue. The macroadenomas were depicted as a less enhanced mass with cavernous sinus invasion in 1 patient and as a non-uniformly enhanced mass in another patient. Bone destruction and incomplete opening of the sellar floor during previous surgery were clearly detected in 2 patients with macroadenomas. These pituitary adenomas were removed via the transnasal route based on information from the MSDCT-MPR images only. The findings were verified surgically. Conclusion: The MSDCT-MPR provided the information needed for surgery with good image quality in the 3 patients with pacemakers. MSDCT-MPR appears to be a useful technique for patients with a pituitary adenoma in whom MR imaging is not available. This is the first report, to our knowledge, of the MSDCT-MPR technique being used to demonstrate pituitary disorders

[en] Intracranial tuberculoma is a rare form of central nervous system tuberculosis. We here report on conventional and diffusion-weighted cranial MR images of a non-immunocompromised patient with multiple intracranial tuberculomas, tuberculous lymphadenitis and pulmonary tuberculosis. Conventional MR imaging revealed multiple ring-enhancing mass lesions. At follow-up MR, appearances of both edema and number and size of nodules were decreased. Diffusion-weighted MR was normal and normal ADC values were found in this case of tuberculomas

[en] Purpose: To analyse and classify structural changes in the transverse ligament in the late stage of whiplash injury by use of high-resolution MRI, and to evaluate the reliability of our classification. Material and Methods: Ninety-two whiplash-injured (2-9 years previously, mean 6 years) and 30 non-injured individuals underwent proton-weighted MR imaging of the craniovertebral junction in three orthogonal planes. Structural changes in the transverse ligaments were graded twice (grades 1-3) based on increased signal, independently by 3 radiologists with a 4-month interval. Inter- and intraobserver statistics were calculated by ordinary and weighted kappa (K). Results: Image quality was excellent in 109 cases and slightly reduced in 13. Twenty-two out of 30 ligaments in the control group were classified as normal (73%) compared with only 32 out of 92 in the injured group (36%). Two or all 3 observers agreed in their grading in 101 out of 122 ligaments (83%). Intraobserver agreement (weighted K) was fair to good (0.33-0.73). Pair-wise interobserver agreement was fair (0.24-0.39). Reasons for divergent grading were insufficient knowledge of normal variations, low signal intensity in the peridental soft tissue obscuring the ligament and interpretation flaw. Conclusion: Whiplash trauma can damage the transverse ligament. By use of high-resolution proton-weighted MR images such lesions can be detected and classified. The reliability of this classification still needs improvement

[en] Purpose: To report a technique of interstitial brachytherapy for the treatment of subcutaneous metastatic abdominal wall tumors. Material and Methods: We developed a brachytherapy technique consisting of ultrasound-guided insertion of applicator needles to avoid the organs at risk, such as intestines, and saline injection into the subcutaneous tissue between the tumor and the skin to decrease the skin dose. We encountered three patients with painful metastases from rectal carcinoma in the abdominal wall refractory to external radiotherapy. They were subjected to this brachytherapy with a single dose of 20 Gy. Results: The procedure was safely achieved in all three patients. Long-lasting pain reduction and tumor shrinkage was obtained without early or late complications. Conclusion: This interstitial brachytherapy technique seems to be feasible in the treatment of metastatic abdominal wall tumors. Keywords: Abdominal wall metastasis; brachytherapy; radiotherapy; rectal cancer

[en] Purpose: To evaluate the radiation dose to the skin, uterus, and ovaries during uterine artery embolization. Material and Methods: Guided uterine artery embolization for leiomyomata and two types of X-ray equipment with different dose levels were utilized during fluoroscopy in 20 women (ages ranging from 32 to 52 years, body weights from 55 to 68 kg). The first 13 women were treated using a non-pulsed system A, with 3.3 mm Al filtering and, for simplicity, a fixed peak voltage 80 kV. During treatment of the other 7 women, a pulsed system B with 5.4 mm Al filtering and an identical fixed voltage was used. The dose area product (DAP) was recorded. The vaginal dose of the first 13 patients and the peak skin dose of all patients were measured with thermoluminescent dosimeters (TLDs). TLDs were placed in the posterior vaginal fornix and on the skin at the beam entrance site. The uterine and ovarian doses were estimated based on the measured skin doses, normalized depth dose, and organ depth values. The effective dose (D eff ) was estimated based on the observed DAP values. The measured vaginal doses and the corresponding estimated uterine doses were compared statistically, as were the DAP values from systems A and B. Results: For system A, the mean fluoroscopic time was 20.9 min (range 12.7-31.1), and for system B 35.9 min (range 16.4-55.4). The mean numbers of angiographic exposures for systems A and B were 82 (range 30-164) and 37 (range 20-72), respectively. The mean peak skin dose for system A was 601.5 mGy (range 279-1030) and for system B 453 mGy (range 257-875). The mean DAP for system A was 88.6 Gy cm² (range 41.4-161.0) and for system B 52.5 Gy cm² (range 20.1-107.9). Statistical analysis showed a significant difference between the DAP values, the DAP for system B being the lower one. The mean estimated effective doses from systems A and B were 32 mSv (range 15.1-58.4) and 22 mSv (range 9-46), respectively. The mean estimated maximum uterine and ovarian doses using system A were 81 mGy (range 30-247) and 85 mGy (range 24-207), respectively; when using system B, the respective doses were 101 mGy (range 45-182) and 105 mGy (range 31-246). The measured vaginal doses had a mean value of 52.5 mGy (range 12-124). Statistical analysis revealed a significant difference between the estimated uterine doses and the measured vaginal doses. Conclusion: A significant difference was found between the estimated uterine doses and the corresponding measured vaginal doses. This has to be kept in mind when using vaginal doses as a substitute for the uterine dose. There was also a significant difference between the DAP values from systems A and B. System B, with pulsed fluoroscopy and greater filtration, gave the lower exposure. The maximum skin dose indicates that skin injuries are unlikely to occur. The ovarian doses are also below the threshold for temporary or permanent sterility. The stochastic risk for radiation-induced cancer and genetic injury to the patient's future children is not considered as substantial

[en] Myotonic dystrophy Curschmann Steinert is a common hereditary disorder that in some cases can be combined with cutaneous tumors, which is an association that is rarely described in the literature. We present the magnetic resonance imaging in the unusual combination of a patient with known myotonic dystrophy and recurrent basal cell tumor

[en] Purpose: To assess the ability of a conventional density mask method to detect mild emphysema by high-resolution computed tomography (HRCT); to analyze factors influencing quantification of mild emphysema; and to validate a new algorithm for detection of mild emphysema. Material and Methods: Fifty-five healthy male smokers and 34 never-smokers, 61-62 years of age, were examined. Emphysema was evaluated visually, by the conventional density mask method, and by a new algorithm compensating for the effects of gravity and artifacts due to motion and the reconstruction algorithm. Effects of the reconstruction algorithm, slice thickness, and various threshold levels on the outcome of the density mask area were evaluated. Results: Forty-nine percent of the smokers had mild emphysema. The density mask area was higher the thinner the slice irrespective of the reconstruction algorithm and threshold level. The sharp algorithm resulted in increased density mask area. The new reconstruction algorithm could discriminate between smokers with and those without mild emphysema, whereas the density mask method could not. The diagnostic ability of the new algorithm was dependent on lung level. At about 90% specificity, sensitivity was 65-100% in the apical levels, but low in the rest of the lung. Conclusion: The conventional density mask method is inadequate for detecting mild emphysema, while the new algorithm improves the diagnostic ability but is nevertheless still imperfect

[en] Purpose: To evaluate any possible advantages of high-concentration gadolinium chelates in the human brain thin-slice MR. Material and Methods: Thirty-six patients were allocated into six groups. Three groups had perfusion imaging performed using 7-mm-thick slices and the other three groups had 4-mm-thick slices. One group who had 7-mm slices and one group of 4-mm slices had 0.5 M gadolinium (20 ml) whilst other groups received the high-concentration gadolinium (1.0 M: 10 ml and 20 ml). The time-intensity curves were analysed for maximum signal reduction and signal-to-noise measurements. Results: Twenty ml of the 1.0-M agent produced significantly increased maximum signal change and improvement in signal-to-noise when compared to 20 ml of 0.5 M. There was no significant difference between the maximum signal change when 20 ml of 0.5 M and 10 ml of 1.0 M agents were compared. There was no significant difference between the maximum signal changes when 7-mm and 4-mm slice thickness using the same dosing regimens. Conclusion: Four-mm slice thickness perfusion imaging can be performed with high-concentration gadolinium in the human brain and we discuss the advantages of this