Acta radiologica. Supplementum最新文献

Cochlear implantation is a treatment for patients with severe sensorineural hearing loss/deafness, who get no help from ordinary hearing aids. The cochlear implant is surgically placed under the skin near the ear and a very thin electrode array is introduced into the cochlea of the inner ear, where it stimulates the remaining nerve fibers (1,2). The operation is complicated; it is performed with the aid of a microscope, and involves drilling very close to vital vessels and important nerves. The method was introduced in Sweden in 1984 by Professor Göran Bredberg, then at Stockholm Söder Hospital. High resolution computed tomography (CT) of the temporal bone is a part of the preoperative evaluation preceding cochlear implantation. It is a method for visualizing the bony structures of the middle and inner ear - to diagnose pathology and to describe the anatomy. In Stockholm, these examinations have usually been performed at the Radiology Department of Stockholm Söder Hospital. Examinations of cochlear implant candidates from other parts of Sweden and from abroad are also sent there for special reviewing. The first work concerns CT of the temporal bone and cochlear implant surgery in children with CHARGE association. This is a rare condition with multiple congenital abnormalities, sometimes lethal. Children with CHARGE have different combinations of disabilities, of which impairments of vision and hearing, as well as balance problems and facial palsy can lead to developmental delay. There have been few reports of radiological temporal bone changes and none of cochlear implant surgery for this group. The work includes a report of the findings on preoperative CT and at surgery, as well as post-implant results in two children. A review of the latest diagnostic criteria of CHARGE and the temporal bone changes found in international literature is also included. The conclusion was that certain combinations of temporal bone changes in CHARGE are, if not specific, at least extremely rare in other materials. CT can visualize these changes and be used as a diagnostic tool. This is important, since some of the associated disabilities are not so obvious from the start. Early treatment is vital for the child's development. This work also shows that cochlear implantation may help some of these often very isolated children to communicate. The second work is a radioanatomic study of one of the structures of the inner ear - the bony canal for the cochlear nerve. It involves measurements of the dimensions of the canal on 117 silicone rubber casts of the temporal bone (from a unique collection of casts at Uppsala temporal bone laboratory) and on 50 clinical CT-studies (100 ears). The purpose was to show the normal variation, which is of use in the appraisal of congenital temporal bone malformations on CT. Based on our results we propose that if the canal is less than 1.4 mm, as measured on CT, the possibility of cochlear nerve abnormality should be considered. Th

Contrast-enhanced magnetic resonance angiography (CE-MRA) is a diagnostic method for imaging of vascular structures based on nuclear magnetic resonance. Vascular enhancement is achieved by injection of a contrast medium (CM). Studies were performed using two different types of CM: conventional paramagnetic CM, and a new type of CM based on hyperpolarized (HP) nuclei. The effects of varying CM concentration with time during image acquisition were studied by means of computer simulations using two different models. It was shown that a rapid concentration variation during encoding of the central parts of k-space could result in signal loss and severe image artifacts. The results were confirmed qualitatively with phantom experiments. A postprocessing method was developed to address problems with simultaneous enhancement of arteries and veins in CE-MRA of the lower extremities. The method was based on the difference in flow-induced phase in the two vessel types. Evaluation of the method was performed with flow phantom measurements and with CE-MRA in two volunteers using standard pulse sequences. The flow-induced phase in the vessels of interest was sufficient to distinguish arteries from veins in the superior-inferior direction. Using this method, the venous enhancement could be extinguished. The possibility of using HP nuclei as CM for CE-MRA was evaluated. Signal expressions for a flow of HP CM imaged with a gradient echo sequence were derived. These signal expressions were confirmed in phantom experiments using HP 129Xe dissolved in ethanol. Studies were also performed with a new CM based on HP 13C. The CM had very long relaxation times (T1, in vivo/T2, in vivo approximately 38/1.3 s). The long relaxation times were utilized in imaging with a fully balanced steady-state free precession pulse sequence (trueFISP), where the optimal flip angle was found to be 180 degrees. CE-MRA with the 13C-based CM in rats resulted in images with high vascular SNR (approximately 500). CE-MRA is a useful clinical tool for diagnosing vascular disease. With the development of new contrast media, based on hyperpolarized nuclei for example, there is a potential for further improvement in the signal levels that can be achieved, enabling a standard of imaging of vessels that is not possible today.

Purpose: The aims of the study was to analyze the features of cancers missed as tumor on ultrasonography (US), to determine the predictive power of US tumor descriptors in the differentiation of benign and malignant breast tumors, to evaluate US as adjunct to mammography, and to assess the validity and reliability of mammographic, US, and combined interpretation of breast tumors.

Material and methods: Prospectively recorded mammographic and US findings of 355 malignant breast tumors among 2,985 consecutive patients who underwent breast US were compared with clinical findings and pathologic subtypes of the tumors. In addition, a 10-year material of 95 invasive lobular carcinomas (ILCs) were investigated. Three retrospective studies assessed the validity and reliability of mammographic, US, and combined interpretation of 200 palpable mammographically noncalcified breast masses by four radiologists.

Results: A total of 97.5% of the palpable and 67.9% of the nonpalpable malignant neoplasms were detected as tumor on US. Most carcinomas missed as tumor on US were ductal carcinomas in situ (DCISs) and microinvasive ductal cancers dominated by DCIS manifesting with suspicious calcifications on mammography. Irregular shape, irregular contour, extensively hypoechogenicity, hyperechoic rim (halo), and distortion of the surrounding tissue were the US features with the highest odds of predicting carcinomas. A pseudocapsule is the strongest predictor of a benign tumor, the odds of cancer being 0.03 in nonpalpable and 0.08 in palpable breast tumors. A negative predictive value of 100% in palpable and 96% in nonpalpable tumors was achieved using strict US criteria. In patients with ILC, US measurements predicted tumor size more accurately than mammography. US as adjunct to mammography correctly diagnosed ("upgraded") 9.5% of tumors with benign or indeterminate mammographic diagnoses. Excluding mammographically conclusive malignant tumors and carcinomas presenting with microcalcifications. US correctly upgraded 42% of the palpable and 44% of the nonpalpable cancers. Combined mammographic-US interpretation offers the highest diagnostic performance in noncalcified breast tumors. The lowest interobserver agreement was found in US interpretation.

Conclusion: The impact of US in mixed cancer populations is limited. US is, however, a valuable adjunct to mammography in patients with nonconclusive mammographic findings. Negative predictive values on US approaching 100% may be achieved using strict criteria for a benign diagnosis. A considerable interobserver variation in the US interpretation is a limiting factor for the potential of breast US in the differentiation of benign and malignant breast tumors.

Radiographic CM are used to change the X-ray absorption of tissue. They have been used since the 1930's and today four main types are available. All these CM are derived from one original structure: the 2,4,6 triiodobenzoic acid with the substituents in positions 1,2 and 5 as a carboxylic group or amides. According to the nature of the substituents and the number of aromatic rings, the four different types of CM can be identified. Three of the four types of CM are hyperosmolar, some of the ionic CM contain meglumine and all CM contain calcium disodium EDTA. To fulfil their role in host defence, circulatory PMN must adhere to endothelium of capillaries and venules adjacent to the inflammatory locus, migrate through the vessel wall to the area of inflammation, phagocytose opsonized bacteria, kill ingested organisms and, finally, inactivate their own toxic products to prevent damage to normal tissue. CM should be biologically inert, but many physiological and pathophysiological effects have been described. This review deals with the present knowledge about the influence of CM on PMN. This thesis presents results of the effects of the four main types of CM on PMN exocytosis of elastase and lactoferrin, adherence to nylon fibers, chemotaxis under agarose and phagocytosis of latex particles, as well after in vitro exposure of CM to PMN and after intravascular injection of CM. After in vitro exposure of CM to whole blood, a dose-dependent fall in lactoferrin and elastase concentration was observed, statistically significant for diatrizoate and ioxaglate at high concentrations. I.v. injection of iohexol or ioxaglate resulted in small, although statistical, decreases in lactoferrin concentration in plasma. No differences between the CM groups were seen. PMN adherence to nylon fibers after incubation of CM with whole blood or isolated PMNs was inhibited. The most inhibitive agents were the ionic CM diatrizoate and ioxaglate. The meglumine ion was found to contribute to the inhibitive effect of diatrizoate upon adherence. Following i.v. injection of iohexol or ioxaglate, increased numbers of PMNs, in combination with decreased adherence, were noted with ioxaglate, and the opposite with iohexol. Immediately after arteriography with iohexol and ioxaglate, a small increase of PMN count, in combination with decreased adherence, could be seen. An inhibition of adherence will result in a shift from the marginal to the circulatory pool of PMNs and thus an increase in PMN count. Although statistically significant the changes were minor. A pronounced increase in PMN count was seen 2-5 hours after arteriography in combination with a decrease in adherence. These changes may be due to a release of glucocorticoids from the adrenals in response to the procedure and/or the injection of CM. CMs do not act as chemoattractants. However, when CM are added to the chemoattractant N-fMLP in the under agarose assay, the number of PMNs migrating (density) was lowered, while

REPORT STUDY: Defaecography reports from 2816 patients were evaluated. Twenty-three percent of the investigations were considered normal, 31% showed rectal intussusception, 13% rectal prolapse, 27% rectocele, and 19% enterocele. A standardised protocol is suggested to ensure a complete evaluation of defaecography. One hundred and ten reports were unclear and reviewed. The unclear reports usually concerned an unexplained widening of the rectovaginal space, and gave incitement to further studies. TECHNIQUE STUDY: Twelve patients with an unexplained widening of the rectovaginal space at defaecography were investigated using defaecography and peritoneography simultaneously, by us named defaeco-peritoneography. All investigations were carried out without complications. Defaeco-peritoneography proved the unexplained widening to be an extension of the pouch of Douglas, a peritoneocele. UNEXPLAINED WIDENING STUDY: Twenty-two patients with unexplained widening of the rectovaginal space noted at defaecography were studied using defaeco-peritoneography. The outline and movements of the peritoneum in the pelvic cavity could be visualised during the dynamic act of defaecation. The unexplained widening of the rectovaginal space was caused completely by a peritoneocele in 14 patients, partially in 6 patients and 2 remained unexplained. However, only 9 out of 22 widenings were peritoneoceles with an enterocele. Just 11 peritoneoceles only contained fluid. Three types of peritoneocele were demonstrated: vaginal, septal, and rectal, with or without enterocele. Combinations of these were also found. RECTAL INTUSSUSCEPTION STUDY: Fifty-seven patients with defaecation disorders were examined using defaeco-peritoneography. Twenty-three patients had rectal intussusception and 7 patients had a rectal prolapse. All these patients had a rectal peritoneocele in the serosal ring-pocket of the rectal intussusception or in the rectal prolapse. Twenty-seven patients had neither rectal intussusception nor rectal prolapse and none of these patients had a rectal peritoneocele. DAILY LIFE STUDY: Twenty-six female patients showing peritoneocele without a contrast-filled rectum at start at defaeco-peritoneography were investigated; 13 of them had enteroceles. Spot radiographs before and after filling the rectum with contrast medium were compared. The peritoneocele disappeared completely in 19 of the patients and was reduced in size in the remaining 7, and the enterocele disappeared completely when the rectum was distended. Defaeco-peritoneography should therefore include a radiograph before the rectum is filled, as it shows the habitual (daily life) anatomy and can disclose pathology as peritoneocele and enterocele. TRANSFORMATION STUDY: Forty-six patients with peritoneocele at defaeco-peritoneography were studied at three different stages during rectal evacuation. At start with contrast-filled rectum, 14 patients had a peritoneocele, and 32 were regarded as normal. At maximum

Contrast-enhanced magnetic resonance imaging (MRI) of the liver and pancreas is frequently performed to improve the sensitivity and specificity of lesion detection in these organs. The concept of using tissue-specific contrast media is to selectively enhance the normal parenchyma, but not lesions, so that the contrast between tumorous and normal tissue is increased, and lesion detectability improved. Mangafodipir trisodium (MnDPDP) has been developed as a hepatocellular-specific contrast agent, but uptake has also been found in pancreatic tissue. In this study the safety and diagnostic efficacy of MnDPDP were investigated in both healthy volunteers and in patients with liver and pancreatic tumors. In healthy volunteers (n = 8), dose-dependent enhancement in T1-weighted images was observed in the normal liver and pancreatic parenchyma after infusion of MnDPDP at doses of 5 and 10 mumol/kg. The maximal enhancement in the two dose groups was 77 and 110% in the liver, and 57 and 84% in the pancreas, respectively. The enhancement-over-time profiles demonstrated that the effective imaging window was about 2 h for the liver, and over 4 h for the pancreas. There was no measurable enhancement in brain structures protected by intact blood-brain barrier, and no changes of clinical importance were found in vital signs or in blood and urinary chemistry variables. Compared with unenhanced images (including T2-weighted images), significantly more lesions were detected on MnDPDP-enhanced T1 images in 82 patients with liver tumors (mostly metastases). Features such as rim enhancement and the enhancement in hepatocellular carcinomas can provide information for differential diagnosis. In a study on patients with pancreatic tumors, mainly adenocarcinomas (n = 21) and islet cell tumors (n = 19), two additional lesions were found in the MnDPDP-enhanced images. The contrast enhancement in the pancreatic parenchyma can vary greatly, depending on the site of the enhancing part of the organ in relation to a large tumor. The tumors of both origins were also enhanced post-contrast, but to a lesser degree than the normal pancreatic tissue. MnDPDP enhancement was investigated in 30 liver metastases from endocrine tumors in 13 patients. These lesions showed a signal increase of about 49% post-contrast, which lasted longer than that in the normal liver tissue. The findings may help to distinguish these tumors from other metastatic tumors. T1-weighted sequences of four types, including a spin-echo and three variants of fast gradient-echo sequences, and various parameter combinations, were investigated in healthy volunteers (n = 6), with the aim of finding the optimal sequence for MnDPDP-enhanced MRI of the liver and pancreas. The fat-and-water out-of-phase, fast field (gradient)-echo sequence was the best for imaging of both the liver and pancreas. The studies have shown that MnDPDP is safe when given as an infusion, and is effective as a liver- and pancreas-specific contr

Certain aspects of the use of CT, MR imaging and PET were evaluated in patients with non-Hodgkin's lymphoma (NHL) with the aim of determining whether these methods may provide practical guidance for improving the management of these patients. Subjective evaluation of the tumor pattern on CT images, and quantification of tracer uptake using 11C methionine (11C Met) and [18F] fluorodeoxyglucose (18FDG) PET in patients with NHL, were performed to determine their relations to malignancy grade. An inhomogeneous tumor pattern (I) was found on CT in 75% of high-grade tumors, whereas 68% of low-grade tumors were homogeneous (H). Sixteen (94%) of the 17 tumors with a severely inhomogeneous pattern (I) were high-grade NHL, while 22 (72%) of the 29 homogeneous tumors (H) were low-grade. All tumors were clearly visualized with both 11C Met and 18FDG PET. The uptake values for 18FDG were significantly-higher in high- than in low-grade tumors, while no significant differences between the prognostic groups were found for 11C Met. A subjective evaluation of the tumor pattern on CT and on MR images was performed. An inhomogeneity index (IH8) was also used in MR images to make a quantitative assessment of the degree of inhomogeneity to determine their relation to prognosis. Patients with localized NHL, treated with radiotherapy, had an excellent prognosis irrespective of the degree of inhomogeneity, while patients with generalized disease, treated with chemotherapy, had a poor prognosis if the tumors were heterogeneous. Among chemotherapy-treated patients, all 9 patients with high IH8 values (> 2.56) on MR images and 9 out of 11 patients with severe inhomogeneities on CT images died. All patients with gastric NHL except for one patient with low-grade NHL of the MALT type displayed high 18FDG uptake at PET corresponding to the pathological findings at endoscopy and/or CT. 18FDG correctly excluded gastric NHL in a patient with benign gastric ulcer, but was unable to discriminate between gastric NHL and gastric carcinoma. The results suggest that 18FDG PET may demonstrate the extension of NHL in the gastric wall more accurately than CT and endoscopy. The prognostic importance of the size of a residual mass after completion of chemotherapy, and of tumor regression rates during chemotherapy, was evaluated in patients with high-grade NHL. Neither a large tumor size before treatment nor a large residual tumor after treatment correlated with relapse. It appears, however, as if the response rate halfway through the therapy may predict the recurrence rate, although statistical significance was not reached.

Problems and aims: The clinical outcome of repeat lumbar discectomy is not as satisfactory as that of the primary surgical procedure. One reason is the difficulty of assessing post-operative radiological investigations and particularly the significance of the various radiological changes. A second problem is differentiating between the two forms of post-operative discitis, a rare but important complication after lumbar discectomy. The aims of this study were: to improve understanding of the significance of certain post-operative radiological changes; and to evaluate differences in the MR features of septic and aseptic post-operative discitis.

Material and methods: A total of 192 patients (209 disc levels) took part in this study; all had had prior lumbar discectomy. Nineteen of these patients were regarded as asymptomatic and they served as a control group in the evaluation of certain post-operative changes in the symptomatic patients. Twelve patients with post-operative discitis were examined in order to compare the MR features of septic and aseptic discitis. MR imaging was performed first without and then with contrast enhancement in all patients. Contrast-enhanced MR imaging was also compared with contrast-enhanced CT.

Results: Owing to its superiority in distinguishing the nerve roots at the surgical site, MR imaging was found to be a more valuable diagnostic method than CT. Disc herniations were found in 16% of the disc levels in asymptomatic patients and in 38% of the disc levels in the symptomatic patients. Significantly more disc herniations were found in patients who had only a short duration of recurrent symptoms (maximum 3 months) before MR investigation than in the asymptomatic patients. Nerve-root displacement due to disc herniation was also significantly more frequent in patients with the short symptom duration than in patients with a longer symptom duration. True intradural nerve-root enhancement was found in 7% of symptomatic patients, and focal enhancement in the root sleeve was found in 26% of them; there was good correlation to clinical symptoms and other pathological findings. Thickened nerve roots were found with equal frequency in asymptomatic and symptomatic patients. Epidural scar tissue diminished with time, showing no significant difference between asymptomatic and symptomatic patients. Out of 6 patients with septic post-operative discitis, 3 showed extensive MR changes; the remaining 3 showed moderate changes which were similar to those in another 6 patients who had aseptic discitis.

Discussion and conclusion: MR is the imaging method of choice in the evaluation of patients with recurrent clinical symptoms after disc surgery. Disc herniations may be found in asymptomatic patients; it is therefore important to assess the plausibility of the assumption that the finding of a herniated disc correlates well with the actual clinical sympt