Therapeutic profile of outpatient radiosurgery with the Gamma Knife system. Part 2: First clinical experiences

Summary Gamma Knife radiosurgery (GKRS) was applied in 500 consecutive treatments for 445 patients within 2 years. Indications were arterio-venous malformations (93 patients), schwannomas of cranial nerves (75 patients), meningiomas (79 patients; 73 of the tumors involving the skull base), pituitary adenomas (40 patients), craniopharyngiomas (13 cases), gliomas (13 cases), rare indications (12 cases), and brain metastases (126 patients). In arterio-venous malformations two complications were observed whereas two other patients underwent surgery due to intracranial hemorrhage in the latent period after GKRS. In all cases follow-up with MRI showed evidence of an active obliteration process. Out of 24 patients with a follow-up over 1 year, angiography revealed complete obliteration in 9 patients so far. A partial obliteration was evidenced by MRI in 15 cases. In benign tumors (meningiomas and vestibular schwannomas) tumor control rates of 88 % and 89 % were achieved, respectively. Treatment related side effects were mild and rare; no facial palsy occured after primary Gamma Knife treatment. GKRS was particularly effective in inoperable skull base meningiomas. Cerebral metastases were controlled in 89.5 % by a single Gamma Knife treatment. The mean survival period was 11.8 months. In patients receiving a single Gamma Knife treatment the mean survival time was 9.1 months. For patients undergoing multiple (up to 5) sessions of GKRS (because of new tumors) the mean survival period was 17.2 months. MRI showed evidence of adverse radiation reactions in 10/124 patients (8.1 %) which were symptomatic in 3 patients (0.8 %). The results obtained in patients with cerebral metastases emphasize that GKRS alone is as effective as the combined treatment of these lesions by surgery and fractionated radiotherapy. Our results demonstrated an attractively high therapeutic gain factor of Gamma Knife treatment in key indications of radiosurgery.      

Intraoperative MRI to control the extent of brain tumor surgery

Purpose: The main aim of our study was to find out whether the combined use of neuronavigation and intraoperative MRI can increase the rate of “complete tumor removal”. The second aim was to characterize the different forms of surgically induced enhancement in order to differentiate them from residual tumor. Materials and methods: Surgery was performed in 18 patients with high-grade glioma. Using a neuronavigation device, the surgeons operated up to the point where they would otherwise have terminated surgery. Intraoperative MRI was then performed to determine whether residual enhancing had been left behind and to update the neuronavigation device. If necessary, feasible surgery was continued. On days 1–3 after surgery early postoperative MRI (1.5 T) was performed. The proportion of patients in whom the enhancing tumor was completely removed was compared with a series of 60 patients with glioblastoma multiforme, who had been operated on using neither neuronavigation nor intraoperative MRI . We also looked for and characterized different types of surgically induced enhancement. Results: Intraoperative MRI definitely showed residual tumor in 6 of the 18 patients and resulted in ambiguous findings in 3 patients. In 7 patients surgery was continued. Early postoperative MRI showed residual tumor in 3 patients and resulted in uncertain findings in 2 patients. The rate of patients in whom complete removal of enhancing tumor could be achieved was 50 % at the time of the intraoperative MR examination and 72 % at the time of the early postoperative MR control. The difference in proportion of patients with “complete tumor removal” between the groups who had been operated on using neuronavigation (NN) and intraoperative MRI (ioMRI) and those who had been operated on using only modern neurosurgical techniques except NN and ioMRI was statistically highly significant (Fisher exact test; P = 0.008). Four different types of surgically induced contrast enhancement were observed. These phenomena carry different confounding potentials with residual tumor. Conclusion: Our preliminary experience with intraoperative MRI in patients with enhancing intraaxial tumors is encouraging. Combined use of neuronavigation and intraoperative MRI was able to increase the proportion of patients in whom complete removal of the enhancing parts of the tumor was achieved. Surgically induced enhancement requires careful analysis of the intraoperative MRI in order not to confuse it with residual tumor.      

隆乳术后的MRI表现

目的分析隆乳术后MRI表现，探讨其临床价值。方法对63例隆乳术后患者行MR扫描，分别分析置入假体和注射假体的MRI表现。结果40例80只乳房行双侧聚丙烯酰胺水凝胶注入，其中50只乳腺假体呈不规则团块游离于腺体内、胸肌内、皮下等各处。7例行双侧白体脂肪注入，其中12只乳内见纤维脂肪团块，6只乳内见脂液平面，6只胸大肌内见脂肪。16例行双侧乳腺假体置入，其中2例行生理盐水假体置入，2只盐水假体破裂；14例行硅胶假体置入，其中4只假体囊外破裂，10只假体囊内破裂。结论MRI是评价乳腺假体置入术后情况的理想方法。     

Rehabilitation of deaf persons with cochlear implants

Summary In the last decade, the rehabilitation of postlingually deaf adults and prelingually deaf children with cochlear implants has been established as a treatment of deafness. The technological development of the implant devices and improvement of the surgical technique have led to a considerable increase of hearing performance during the last years. The postlingually deaf adults are able to use the telephone and may be integrated in their original job. Prelingually deaf children can even visit normal schools after cochlear implantation and hearing rehabilitation training. In order to preoperatively establish the state of the cochlea, radiological diagnosis of the temporal bone is necessary. High resolution computerized tomography imaging of the temporal bone with coronar and axial 1 mm slices and MRI with thin slice technique (three dimensional, T2 weighted turbo-spinecho sequence with 0.7 mm slices) have proved to be valuable according to our experience. Furthermore a postoperative synoptical X-ray, in a modified Chausse III projection, offers good information about the position of the implant and insertion of the stimulating electrode into the cochlea.      

The diagnosis of breast implant rupture: MRI findings compared with findings at explantation

STUDY OBJECTIVE: The aim of this study was to evaluate the accuracy of Magnetic Resonance Imaging (MRI) as performed according to a strict study protocol in diagnosing rupture of silicone breast implants. MATERIAL AND METHODS: The study population consisted of 64 women with 118 implants, who had participated in either one or two study MRI examinations, aiming at determining the prevalence and incidence of silent implant rupture, respectively, and who subsequently underwent explantation. Implant rupture status was determined by four independent readers and a consensus diagnosis of either rupture (intracapsular or extracapsular), possible rupture or intact implant was then obtained. Strict predetermined rupture criteria were applied as described in this report and findings at surgery were abstracted in a standardised manner and results compared. RESULTS: At MRI, 66 implants were diagnosed as ruptured, nine as possibly ruptured and 43 as intact. Among the ruptured implants, 27 were categorized as extracapsular. At surgery, on average 297 days after the MRI, 65 of the 66 rupture diagnoses were confirmed, as were 20 of the cases with extracapsular silicone. Eight of the nine possibly ruptured implants were in fact ruptured at surgery. Thirty-four of the 43 intact implants were described as intact at surgery. When categorising possible ruptures as ruptures, there were one false positive and nine false negative rupture diagnoses at MRI yielding an accuracy of 92%, a sensitivity of 89%, and a specificity of 97%. Correspondingly, the predictive value of a positive MRI examination was 99% and the predictive value of a negative MRI examination was 79%. CONCLUSIONS: We conclude that MRI is highly accurate for identification of silicone breast implant rupture, with a high sensitivity and specificity when evaluation of images are based on presence of well-defined rupture criteria.     

Inconclusive findings at mammography: the value of MR imaging

Summary Purpose: To evaluate the usefulness of magnetic resonance (MR) imaging in the assessment of inconclusive findings at mammography, such as indeterminate focal or diffuse breast abnormalities, post-treatment breasts with extensive scarring, dense breasts, and findings suggesting multifocal or multicentric breast cancer. Material and Methods: 254 patients underwent mammography, sonography, and MRI of the breast. Dynamic MR imaging was done using a thin-section three-dimensional gradient-echo sequence (FLASH, TR = 11.8 ms; TE = 5 ms; flip angle = 25 °) which was applied in a dynamic fashion before and every 90 seconds after injection of gadopentetate dimeglumine. Diagnoses were confirmed at biopsy (n = 165) or by follow-up (n = 89). Results: Among various breast anomalies, the highest proportion of breast cancers was associated with dense breast tissue (27.8 %), architectural distortion (26.9 %), and irregular scars (15.8 %). Sensitivity of dynamic MR imaging was 93.7 %, and specificity was 83.3 %. As compared to mammography and sonography, MR detected 6 occult carcinomas, and showed additional malignant lesions in 19/63 women (30.2 %) with biopsy-proven breast cancer. Conclusion: MR imaging of the breast may provide valuable additional information in indeterminate breast anomalies. However, because of its inherent limitations, it should not replace core needle biopsy in all lesions which are amenable to biopsy. Because of its high sensitivity in the detection of invasive carcinomas in any type of breast tissue, MR imaging is considered the modality of choice in the evaluation of dense breasts in high-risk patients or in patients with clinical suspicion of occult breast cancer, and for preoperative tumor staging.      

Prevalence of rupture of silicone gel breast implants revealed on MR imaging in a population of women in Birmingham, Alabama

OBJECTIVE. Silicone gel breast implants have been reported to rupture, but the prevalence of implant rupture in an unreferred population of women is not known. The objective of this study was to assess the prevalence of implant rupture and the presence of extracapsular silicone gel in an unreferred population of women without regard to the absence or presence of any local or systemic symptoms. SUBJECTS AND METHODS. Women identified as part of a National Cancer Institute cohort study on breast implants, living in the Birmingham, AL, area were invited to undergo MR imaging of their current silicone gel breast implants at the Kirklin Clinic at the University of Alabama at Birmingham. Three radiologists independently examined and rated all MR images for signs of implant rupture and extracapsular silicone. RESULTS. A total of 344 women with silicone gel breast implants underwent MR imaging. Breast implant rupture was reported by at least two of three radiologists for 378 (55.0%) of the 687 implants in this study. Another 50 implants (7.2%) were rated as indeterminate (suspicious) for rupture. A majority of women in this study, 265 (77.0%) of 344, had at least one breast implant that was rated as ruptured or indeterminate. Radiologists also agreed that silicone gel could be seen outside the fibrous capsule that forms around the implant in 85 (12.4%) of the 687 implants affecting 73 women (21.2%). Factors that affected implant rupture were implant age and location (submuscular or subglandular). The median implant age at rupture was estimated to be 10.8 years with a 95% confidence interval of 8.4-13.9 years. CONCLUSION. The prevalence of silent or occult silicone gel breast implant rupture is higher than was previously suspected. Most women in this study had MR imaging evidence of at least one ruptured silicone gel breast implant.     

MRT of the abdomen in combination with enteroclysis in Crohn disease with oral and intravenous Gd-DTPA

Summary In spite of the improved MR-diagnosis of the abdomen, MRI is not used as a routine method for the diagnosis of inflammatory small bowel disease. The aim of this study was – after optimazation of the bowel opacification – the correlation of the findings obtained with enteroclysis and MRI in patients with known Crohns' disease. 60 patients beween 17 and 72 years of age were investigated. First, an enteroclysis was performed in typical manner. The applicated methylcellulosis was blended with positive oral MR contrast media (Magnevist oral, Schering). After enteroclysis, MRI of the abdomen was performed using T1- and T2-weighted breathhold sequences (Flash 2D pre- and postcontrast and TSE) in axial and coronal planes. The lenght of the affected bowel and the stenosis seen with enteroclysis correlated well with the visible thickening of the small bowel wall and the stenosis seen in MRI. Using MRI, additional findings could be obtained in 28 patients, such as fistulas, abscesses or a hydronephrosis, or a better assessment of the stenosis was possible with MRI, because of the avoidance of overshadowing of the affected bowel loop with MRI. A brilliant MR-tomographic imaging of the small bowel is possible under the condition, that the small bowel contrast is optimal. The main prerequisite is a large filling volume of the small bowel to reach a homogeneous contrast and a good distension of the small bowel lumen.      

Breathhold MRI of the small bowel in Crohn's disease after enteroklysis with oral magnetic particles

Purpose: To evaluate the efficacy of breathhold MRI following enteroclysis with addition of oral magnetic particles to study the extension, detection of stenoses and extraluminal manifestations in Crohn's disease. Material and Methods: 18 patients with Crohn's disease and potential of surgical intervention were studied with enteroclysis with addition of oral magnetic particles. T1-/T2-weighted breathhold MRI w/o spectral fat suppression w/o i. v. Gd-DTPA was applied. Results: Typical findings were marked bowel wall thickening with strong contrast enhancement. 95.8 % of affected small bowel segments and 94.7 % of stenoses were correctly detected by MRI. All four fistulas were detected and important extraluminal findings were seen in 6/18 patients. Additionally, one ileoileal and two ileosigmoidal adhesions, two extraluminal abscesses and affection of the right ureter were delineated. Conclusion: MRI in Crohn's disease offers the potential to avoid radiation exposure in this relatively young patient group. Important additional findings relevant to indication of surgery are seen in approximately one third of cases. The replacement of transduodenal intubation by oral contrast application remains to be further studied.      

Computer tomography in children and adolescents with suspected malformation of the petrous portion of the temporal bone

Purpose: To demonstrate HRCT findings and their therapeutic relevance in suspected congenital hearing disorders. Material and Methods: It was checked in 96 young patients if HRCT findings of the temporal bone could explain functional findings. Furthermore, the therapeutic consequences were noted. Results: Normal CT and normal functional findings were obtained in 49 temporal bones (TB). In conductive hearing loss (41 TB), dysplasias of the conducting apparatus (37 TB) and inflammatory changes (3 TB) were found. Combined hearing loss (18 TB) was clarified completely or partially in half the cases. There were 22 dysplasias of the inner ear, 3 dysplasias of the middle ear, 1 abandoned examination (2 TB), and 55 normal CT findings in senorineural hearing disorders (82 TB). 1 retardate had a malformation of the inner ear and, contralaterally, inflammatory middle ear. In cases of vestibular disorders (24 TB), 14 malformations of the inner ear were detected. An indication for an operation was given in 23 TB. In 22 TB, it was contraindicated. The CT was one preliminary examination to a cochlea implant in 19 patients. The therapy was carried on with hearing devices in the other patients. Conclusion: HRCT is an important method in diagnosis and therapeutic planning of suspected malformations of the temporal bone.      

Comparison of cerebral perfusion reserve and collateral circulation in patients with internal carotid artery disease

Summary The cerebral hemodynamics in patients with carotid disease is influenced by a network of extra- and intracranial collaterals. The purpose of this study was to compare the findings of regional cerebral perfusion reserve (rCPR) with angiographically proven collateral circulation. In 41 patients (28 men, 13 women, age 63 ± 10 years) with angiographically proven carotid stenoses or occlusions (30 stenoses, 11 occlusions) 24 ^{99 m}Tc-HMPAO-SPECT and 25 dynamic Xe-CT investigations were conducted, both before and after acetazolamide stimulation. rCPR was quantified as the ratio (1) of the absolute rCBF values obtained by Xe-CT and (2) of the count density measured by HMPAO-SPECT of the acetazolamide administration. A rCPR of less than 95 % in a vascular territory was classified as compromised rCPR. A recent CT examination was available in all cases. According to the angiographic findings the patients could be classified into (1) group A (n = 9) with residual carotid perfusion, (2) Group B (n = 8) with collateralization via the circle of Willis, and (3) group C (n = 24) with leptomeningeal or ophthalmic artery collateral circulation. The rCPR values were significantly different in groups B and C with both methods, Xe-CT (P = 0.0035) and HMPAO-SPECT (P = 0.0014). rCPR was decreased in 13/14 group C patients investigated with Xe-CT and in 11/14 examined with HMPAO-SPECT. All patients in group B showed normal rCPR according to Xe-CT and HMPAO-SPECT. In group A, six of seven revealed decreased rCPR on Xe-CT, while rCPR values were normal in all four group A-patients examined with HMPAO-SPECT. The cerebral hemodynamics depend on a collateralization network and not only on the degree of internal carotid artery (ICA) stenosis. A decreased CPR in a vascular territory ipsilateral to an ICA stenosis or occlusion correlates strongly with the angiographic finding of leptomeningeal or ophthalmic artery collateral circulation.      

The value of ultrasonography of the Achilles tendon in traumatology

Summary Method: In an experimental study on ten isolated human cadaver tendons, the ultrasound anatomy and the reproducibility of aretefacts was determined using 10- and 13-MHz probes. With these in vitro data, the form and diameter of a non-injured tendon were documented in a series of 30 patients between 3 and 60 years old. In a second series of 32 patients with acute, traumatic ruptures of the Achilles tendon and 40 patients with chronic disorders, we distinguished the pathological anatomy. Results: Injuries to a tendon with chronic disorders, reruptures and complications in the postoperative period after tendon repair can be made more difficult by calcification, scars, oedema, haematoma and suture materials. It is necessary to check the changing ultrasound patterns owing to an haematoma or oedema with tendon corpulence, the missing linear signals in a fresh rupture and the different signals after operative or non-operative treatment. Conclusion: Using high-frequency probes with 10 or more MHz, it is possible to examine even the insertion area of the tendon or the pathology of a subachilleal bursa by tilting the probe. The dynamic examination and the comparison with the contralateral side in two planes should be included in a standardized examination procedure and are of great importance in some cases of fresh tendon ruptures. Knowledge of the physical principles and the possibility of misleading artefacts is crucial.      

MRI diagnosis of anterior cruciate ligament lesions: comparison of 1.0 T and 0.2 T. Early results

Summary The purpose of our study was to compare the diagnostic performance of a 0.2-T MRI unit and a 1.0-T MRI unit in the evaluation of the anterior cruciate ligament in patients with clinically suspected lesions of this ligament. Twenty four patients with clinically suspected lesions of the anterior cruciate ligament underwent MRI of the knee on both 0.2-T and 1.0-T MRI units. Three independent observers evaluated the examinations for primary and secondary signs of a tear of the anterior cruciate ligament. Frequency of these signs was determined for both modalities, and observer agreement was assessed using the kappa statistic. Sixteen of 24 patients had signs of tears of the anterior cruciate ligament on the 1.0-T unit; the 0.2-T unit detected primary signs in 15/16 (93 %) patients and secondary signs in 7/12 (43 %) patients. In 8 patients the 1.0 T unit showed neither primary nor secondary signs for tears of the anterior cruciate ligament; in these patients the 0.2-T unit detected primary signs in 1/8 cases (12 %), and secondary signs in 3/8 cases (37 %). Observer agreement was very good for the 1.0-T unit and fair for the 0.2-T unit. There is no substantial difference between 1.0-T units and 0.2-T MRI units in the visualisation of primary signs of tears of the anterior cruciate ligament. In the visualisation of secondary signs, 1.0-T units are superior to 0.2-T units, and there is a surprisingly high rate of false-positive results with the 0.2-T unit. As to the reproducibility of the results, the 1.0-T unit is far superior to the 0.2-T unit.      

Videofluoroscopic evaluation of complications after laryngeal resection

Summary In past decades, the surgical techniques for treating laryngeal carcinoma have been vastly improved. For circumscribed tumors, voice-conserving resections are possible and for extensive neoplasms, radical laryngectomy, sometimes combined with chemoradiation, has been developed. Postoperative complications regarding swallowing function are not uncommon. Radiologic examinations, especially pharyngography and videofluoroscopy, are most often used to evaluate patients with complications after laryngeal surgery. An optimized videofluoroscopic technique for evaluation of complications is described. The radiologic appearance of early and late complications, such as fistulas, hematomas, aspiration, strictures, dysfunction of the pharyngoesophageal sphincter, tumor recurrence, and metachronous tumors is demonstrated.      

CT and MRI of the middle ear

Summary High-resolution computed tomography (HRCT) provides excellent contrast between osseous structures, air and soft tissue in conjunction with high spatial resolution. Therefore, thin-section HRCT with bone window setting is the method of choice for the examination of the middle ear structures. The indications are acute and chronic inflammatory changes, cholesteatoma and tumor, the “postoperative middle ear”, and malformations. In most cases, HRCT enables differentiation between inflammatory changes, cholesteatoma, and tumor. The excellent depiction of subtle osseous details enables the identification of erosions of the ossicles or of the bony walls of the mastoid cells, of osseous defects of the tegmen, of the bony labyrinth, and of the tympanic course of the facial canal. In addition, HRCT enables excellent depiction of reconstructions of the ossicles or prosthesis of the ossicles. Although HRCT is the first method of choice, magnetic resonance imaging (MRI) may provide additional information and lead to a more accurate diagnosis in some cases. This is explained by the excellent soft tissue contrast provided by MRI. In addition, MRI offers the possibility of using various pulse sequences and the administration of IV contrast material. Therefore, MRI may allow the differentiation between inflammatory changes, cholesteatoma, and tumor in those cases in which accurate diagnosis cannot be made by HRCT. The differentiation between a meningocele or meningoencephalocele and other entities such as tumors or cholesteatoma can be established by MRI. Furthermore, MRI can accurately depict cases of labyrinthitis or of neuritis of the facial nerve or of intracranial disease caused by middle ear processes, while this is not always possible by HRCT. In summary, HRCT of the middle ear is the method of choice, but MRI may provide supplementary information in those cases in which accurate diagnosis cannot be established by HRCT.      

乳房假体植入后破裂及漏出的MRI表现

目的 探讨MRI诊断乳房假体破裂和(或)泄漏的临床价值. 资料与方法 对15例隆乳术后患者行MR扫描,对囊袋假体及注射聚丙烯酰胺假体的MR表现进行分类分析,与正常假体对照. 结果 硅胶囊袋单腔假体13例26个,囊内为硅胶液;1例2个为双囊假体,外囊为生理盐水,内囊为硅胶液.其中正常假体5例,均为单囊硅胶囊袋假体.硅胶囊袋单腔假体破裂8例16个,其中1例属囊内破裂,MRI示残留塌陷的硅胶囊袋呈长条状长T1、短T2信号;其余为囊内、外均破裂,MRI示假体内有多发条、丝状长T1短T2信号,即"条丝征"、"舌样征",同侧乳房外见假体内容物颗粒.注射聚丙烯酰胺假体1例2个,完全破裂,表现为多发条块状、结节状长T1、长T2信号,MRI表现为假体内有多发"条丝征". 结论 MR检查可明确乳房假体的类型、位置;明确假体破裂的类型及漏出物的分布范围;因此能为临床手术提供准确定位,为随访复查提供客观资料.     

Hand and wrist imaging using a low-field dedicated MRI system

Summary Purpose of this study was to evaluate the diagnostic value of a low field dedicated MRI system in hand and wrist imaging. All 308 exams of the hand and wrist, that were performed on a low-field dedicated MRI system (Artoscan, Esaote Biomedica, Italy) in our institution in 1996, and high-field MRI exams performed in addition as part of the diagnostic work-up, were evaluated and correlated to final operative (n = 64) and histologic (n = 12) reports. 90 % of all low-field MRI scans stated a diagnosis according to clinical suspicion. In 62 % the clinical question was answered, and in 26 % additional pathologies were identified. An MR-diagnosis completely different from the clinical suspicion was stated in 2 %. High field exams contributed additional information in 6 of 36 patients. In 3 patients a tumor was not shown completely in the limited field-of-view of the dedicated low-field MRI-system. Frequency-selective fat-suppression pulse sequences and a better spatial resolution were the reasons for the additional information obtained in the other three patients. Low-field dedicated MR-imaging is a valuable method in the extensive work-up of the hand and wrist. Osseous, ligamentous and tendinous pathologies are well depicted. Large or infiltrative tumors should be referred to a high-field system.      

Migration and Accumulation of Silicone in the Liver of Women with Silicone Gel-Filled Breast Implants

¹H NMR localized spectroscopy (STEAM), combined with echocardiography (ECG), respiratory gating, and water and fat suppression, was used to quantify silicone concentrations in the liver of women with silicone gel-filled breast implants. Localized spectroscopy was performed on 15 patients with silicone gel-filled breast prostheses and on eight volunteers with no implants. The ¹H spectra in the liver of patients showed silicone resonances from 0.3 to ?0.8 ppm, attributable to protons in the methyl groups of silicone. The presence of silicone in the liver could first be detected 3–4 years after breast prostheses implantation. No correlation between silicone concentrations and implantation times was observed. However, our results indicated that silicone concentrations may reflect implant integrity: detectable silicone concentrations in the liver appeared to be higher when the implants were ruptured than when the implants appeared intact. Moreover, new resonances in the range of ?2.6 to ?4 ppm were observed in most patients after long-term implantation. As these species increase with implantation time, the new resonances may reflect chemically changed silicone (paramag-netically shifted silicon complexes bound to iron) accumulated over time. The sensitivity of ¹H NMR localized spectroscopy is sufficient to detect silicon concentrations as low as 0.20 mM. Results from one patient whose implants had been removed 14 months prior to the NMR examination showed no detectable silicone in the liver, indicating that it may have been excreted via bile or degraded to silica and high coordinated silicon complexes. Quantitative ¹H localized spectroscopy of the liver in women with silicone gel-filled breast implants may provide valuable information concerning silicone accumulation and degradation in vivo, as well as about the kinetics of its elimination from the body after implant removal.     

MRI of the fingers in patients with systemic scleroderma. Early results of contrast-enhanced examinations on a dedicated MRI system

Purpose. To estimate disease activity in patients with systemic sclerosis using contrast-enhanced MRI of the skin. Material and Methods. In a pre-study, sequences of a low-field (0.2 T) scanner (Artoscan, Esaote, Genova, Italy) were optimized for detection of intravenous contrast (0.1 mmol/l Gd-DTPA) in six patients with the autoimmune disease systemic scleroderma. Based on the results of the pre-study, 17 patients with scleroderma (7 sclerotic/10 active inflammatory disease) were scanned using gradient-spoiled 3D GRE sequences (FA 90 °, TR 100 ms, TE 18 ms), which had been established as most sensitive for intravenous contrast. Contrast enhancement of the skin was determined quantitatively by contrast-to-noise ratios (CNR), comparing post- to pre-contrast and dynamic scans (for 6 min, 1 acquisition/min). Patients in the chronic state with sclerodactylia and active inflammation of the hands were considered separately and compared to a control group (n = 10) matched according to age. Results. CNR increase after intravenous contrast was significantly higher in patients with active disease (86 ± 16 % increase) than sclerosing disease (29 ± 3 %, p < 0.05) and the control group (4 ± 2 %, p < 0.05). The dynamic examination showed a significantly slower decrease after the peak rise in the first minute in patients with active disease (CNR 15.4 ± 0.7 to 14.2 ± 1.4) than in those with chronic disease (14.1 ± 0.5 to 11.3 ± 0.9, p < 0.05). Discussion. Capillary leakage is the most likely explanation for the increased enhancement in patients with active scleroderma. Using sequences optimized for contrast detection, disease activity in the course of scleroderma and response to therapy can be determined by MRI in the future.      

Rationale diagnostic approach to biliary tract imaging

Summary Since the introduction of MR cholangiography (MRC) diagnostic imaging of the biliary tract has been significantly improved. While percutaneous ultrasonography is still the primary examination, computed tomography (CT), conventional magnetic resonance imaging (MRI), as well as the direct imaging modalities of the biliary tract – iv cholangiography, endoscopic-retrograde-cholangiography (ERC), and percutaneous-transhepatic-cholangiography (PTC) are in use. This article discusses the clinical value of the different diagnostic techniques for the various biliary pathologies with special attention to recent developments in MRC techniques. An algorithm is presented offering a rational approach to biliary disorders. With further technical improvement shifts from ERC(P) to MRC(P) for biliary imaging could be envisioned, ERCP further concentrating on its role as a minimal invasive treatment option.