ADC mapping of chronic cerebral hypoperfusion induced by carotid artery stenosis.

BACKGROUND: Carotid artery stenosis is associated with the occurrence of acute and chronic ischemic lesions that increase with age in the elderly population. Diffusion Imaging and ADC mapping may be an appropriate method to investigate patients with chronic hypoperfusion consecutive to carotid stenosis. This non-invasive technique allows to investigate brain integrity and structure, in particular hypoperfusion induced by carotid stenosis diseases. The aim of this study was to evaluate the impact of a carotid stenosis on the parenchyma using ADC mapping. METHODS: Fifty-nine patients with symptomatic (33) and asymptomatic (26) carotid stenosis were recruited from our multidisciplinary consultation. Both groups demonstrated a similar degree of stenosis. All patients underwent MRI of the brain including diffusion-weighted MR imaging with ADC mapping. Regions of interest were defined in the anterior and posterior paraventricular regions both ipsilateral and contralateral to the stenosis (anterior circulation). The same analysis was performed for the thalamic and occipital regions (posterior circulation). RESULTS: ADC values of the affected vascular territory were significantly higher on the side of the stenosis in the periventricular anterior (P<0.001) and posterior (P<0.01) area. There was no difference between ipsilateral and contralateral ADC values in the thalamic and occipital regions. CONCLUSIONS: We have shown that carotid stenosis is associated with significantly higher ADC values in the anterior circulation, probably reflecting an impact of chronic hypoperfusion on the brain parenchyma in symptomatic and asymptomatic patients. This is consistent with previous data in the literature.

[Pretherapeutic and posttherapeutic laryngeal imaging]. / Prä- und posttherapeutische Larynxbildgebung.

Cross-sectional imaging with CT, MRI and more recently PET CT plays an indispensable complementary role to endoscopy in the pretherapeutic diagnostic and staging of laryngeal neoplasms and in the evaluation of the operated or irradiated larynx. Adequate interpretation of the CT, PET CT and MR images requires a thorough knowledge of the patterns of submucosal spread and familiarity with the diagnostic signs of neoplastic invasion as seen with each modality. In addition, one should be aware of the implications of imaging for staging and treatment. Both CT and MR imaging are highly sensitive for the detection of neoplastic invasion of the preepiglottic and paraglottic spaces, subglottic region and cartilage. The high negative predictive value of both CT and MRI allows a relatively reliable exclusion of neoplasm cartilage invasion. The specificity of both CT and MRI is, however, moderately high and both methods may, therefore, overestimate the extent of tumor spread. However, recent investigations have shown that the specificity of MRI may be significantly improved by using new diagnostic criteria which allow differentiation of tumor from peritumoral inflammation in many instances. Both cross-sectional imaging methods also significantly improve the pretherapeutic staging accuracy of laryngeal tumors if used in addition to clinical examination and endoscopic biopsy. In the presence of a submucosal mass, CT and MRI play a key role for the diagnosis, as they may characterize the lesion, reliably depict its submucosal extent and guide the endoscopist to perform deep biopsies which allow the definitive histological diagnosis. Cross-sectional imaging also plays a key role in the evaluation of laryngoceles, recurrent laryngeal nerve paralysis and fractures.

Brain and spine MRI artifacts at 3Tesla.

INTRODUCTION: We illustrate here the most common MRI artifacts found on routine 3T clinical neuroradiology that can simulate pathology and interfere with diagnosis. MATERIALS AND METHODS: Our group has worked with a 3-T Magnetom Trio (Siemens, Erlangen, Germany) system for two years, with 50% of our time devoted to clinical work and 50% dedicated to research; 65% of the clinical time is dedicated to neuroradiology (2705 patients) and the remaining time to whole-body MRI. We have detected these artifacts during our case readings and have selected the most representative of each type to illustrate here. RESULTS: We have observed magnetic susceptibility artifacts (29%), pulsation artifacts (57%), homogeneity artifacts (3%), motion artifacts (6%), truncation artifacts (3%) and, finally, artifacts due to poor or inadequate technique in the examined region. CONCLUSION: High-field imaging offers the benefit of a higher signal-to-noise ratio, thus making possible the options of a higher imaging matrix, thinner slices, the use of spectroscopy and diffusion tensor imaging in the routine clinical neuroradiology with a reduction in time spent. It is vital to be able to recognize these artifacts in everyday practice as they can mimic pathological appearances, thus causing diagnostic errors that could lead to unnecessary treatment. Indeed, most of these artifacts could be avoided with an adequate technique.

[Minimally invasive ablation techniques for small kidney tumors: cryoablation and radiofrequency]. / Traitement minimalement invasif des petites tumeurs du rein par cryothérapie et radiofréquence.

Over the last years, the development of minimally invasive surgery using percutaneous or laparoscopic ablative techniques for the treatment of small renal tumours has become more common. Cryotherapy and radiofrequency option have been now integrated in the armamentarium of the urologist. These approaches seem to be an attractive alternative to extirpative surgery in selected high-risk patients and offer on a short time basis equivalent cancer control to conventional surgery. This review presents recent data with regard to the use of cryotherapy and radiofrequency in the treatment of small renal tumours. These techniques will obviously have to stand the test of time.

Vascular invasion in pancreatic cancer: evaluation of endoscopic ultrasonography, computed tomography, ultrasonography, and angiography.

PRINCIPLES: Current methods for detecting vascular invasion in pancreatic cancer can be inaccurate, invasive, and expensive. The aim of this study is to assess the value of current imaging modalities in determining vascular invasion by pancreatic cancer. METHODS: The results of Endoscopic Ultrasonography (EUS), Computed Tomography (CT), Ultrasonography (US), and Angiography performed in 170 patients, suffering from pancreatic cancer, were retrospectively studied and correlated with intra-operative findings and surgical anatomopathological diagnosis after resection. We assessed sensitivity, specificity, positive and negative predictive values, and accuracy for detecting vascular invasion. RESULTS: EUS turned out to be the most reliable imaging technique for detecting vascular invasion in pancreatic cancer, with a sensitivity of 55%, specificity of 90%, positive predictive value of 61.1%, negative predictive value of 87.5%, and accuracy of 82.2%. CT results were 39.4%, 90%, 52%, 84.4%, and 79.1% for the respective categories, with however, better results with multislice CT. The US results were 3.7% for the sensitivity, 96.3% for the specificity, 25% for the positive predictive value, 75.2% for the negative predictive value, and 73.4% for the accuracy. For angiography, the sensitivity, the specificity, the positive predictive value, the negative predictive value, and the accuracy were 52.6%, 72.3%, 43.5%, 79.1%, and 66.7% respectively. CONCLUSION: In this study, EUS was the most valuable imaging modality in assessing vascular invasion (especially for venous invasion) for pancreatic cancer, with an accuracy of more than 80%. A further prospective study should be carried out to evaluate the combination of imaging modalities for the detection of vascular involvement, especially with multi-slice CT which almost reached the performances obtained by EUS.

An animal model for radiologic biliary interventional procedures.

Procedural development, in vivo evaluation, and professional training in interventional biliary radiology require an animal model that provides easy and safe access to the gallbladder and bile ducts. A porcine model was used successfully for catheterization of the biliary system under fluoroscopic control. Permanent access to the gallbladder of ten pigs was achieved with a large-bore cholecystostomy catheter. Catheterization of the common bile duct through the cystic duct was feasible in all animals. Repeated interventional radiologic procedures were performed with intramuscular sedation of the animals, which made this model particularly useful for studies requiring multiple procedures or serial follow-up over several weeks. This article describes the technical aspects of the animal model and the radiographic anatomy of the extrahepatic biliary system in 27 domestic pigs.

Biological effects of biliary shock wave lithotripsy in swine.

Extracorporeal shock waves generated with an electromagnetic lithotriptor of the second generation were administered to the gallbladder or bile ducts of 24 domestic piglets. In six animals, fresh human cholesterol gallstones were implanted into the gallbladder two weeks before shock wave administration. Treatment with 3,000 shock waves resulted in fragmentation of the majority of the gallstones in all six animals. In the other animals, 3,000 shock waves (n = 12) or 6,000 shock waves (n = 6) were directed at the gallbladder or the bile ducts without previous stone implantation. Twelve of all 24 animals were killed immediately after shock wave treatment, the other 12 after one week. Autopsy in all 24 animals revealed no gross traumatic changes; the peritoneal fluid was clear in all 24 animals. Microscopically, acute hemorrhage was found in the gallbladder wall (3/12 animals) or in the portal fissure and right lung base (1/12 animals) in those animals who were killed immediately. After one week, resolving hemorrhage with scar formation was found in the right or left lung base in 2/12 animals.

Ablation of the cystic duct and the gallbladder. Experimental basis and initial clinical observations.

Bipolar radiofrequency electrocoagulation of the cystic duct by catheter can be performed safely and reproducibly using fluoroscopic control and induces endoluminal scar formation. The scar within the cystic duct forms a reliable barrier between the gallbladder and the biliary system and avoids recanalization of the cystic duct at a later date. Sclerotherapy of the isolated gallbladder with 95% ethanol and 3% STS can be performed without toxic or otherwise adverse effects and is suitable to ablate the porcine gallbladder. Initial clinical trials with this new technique on a small number of patients are promising and have demonstrated that the protocol can be applied safely to humans. The electrocoagulation technique by catheter appears suitable to ablate the human cystic duct. Follow-up evaluation of our first patients is under way and must determine whether our regimen is appropriate to ablate the human gallbladder on a long-term basis. Further development of this new approach may eventually enable definitive nonoperative treatment of cholecystolithiasis in selected patients.

Human amnion as a bioprosthesis for bile duct reconstruction in the pig.

Despite technical advances in management, the complication of late stricture formation and biliary sepsis still occur in bile duct reconstruction. In an attempt to avoid bilioenteric anastomosis, which bypasses the biliary sphincter mechanism, various biologic and artificial materials have been employed clinically and experimentally to replace the damaged bile duct. No satisfactory biliary replacement material has yet been found. In the experimental model of bile duct stricture that has been presented, human amnion bile duct injuries mimicking those seen in clinical practice were repaired using human amnion as a free graft. Noncircumferential duct loss appeared to be satisfactorily repaired using amnion, and the amnion repair was found to be as good as or superior to plastic repair; however, circumferential duct loss was not adequately repaired with the amnion graft.

Soft-tissue effects of biliary extracorporeal shockwave lithotripsy in swine.

This study investigates the soft-tissue effects of biliary extracorporeal shockwave lithotripsy (BESWL) using a recently developed lithotripter, which consists of an electromagnetic shockwave generator and an integrated ultrasonic targeting system. Sixteen swine, evenly divided into four groups, underwent BESWL. One group had one BESWL session targeted on the gallbladder and another group had two BESWL sessions targeted on the gallbladder. The third group had one BESWL session targeted on implanted gallbladder stones and the fourth group had one BESWL session targeted on the region of the common bile duct (CBD). Half of each group were sacrificed on the day of lithotripsy and half 1 week later. Post-mortem examinations were performed. Each implanted gallstone had fragmented. There were no findings attributable to BESWL in 11 animals. Three animals had pulmonary haemorrhagic spots (the largest was 10 mm in diameter) and one had a submucosal CBD petechia; these findings were attributable to BESWL. In two animals, microscopic haemorrhage associated with bronchopneumonia (usually present in our pig population) was more prominent than usual. This was possibly attributable to BESWL. The swine's deep posterior costophrenic sulcus makes it difficult to avoid the lung base during BESWL in swine. We conclude that this BESWL device can fragment gallstones without causing clinically significant soft-tissue damage.

[Mirizzi syndrome: anamnesis, diagnosis and therapy based on 5 cases]. / Das Mirizzi-Syndrom: Anamnese, Diagnostik und Therapie anhand von 5 Fällen.

It is reported on 5 patients with Mirizzi syndrome. This syndrome is defined by the trias "chronic cholecystitis, cholelithiasis and benign stenosis of the hepatic duct with jaundice". The biliobiliary fistulas are the more severe forms of this syndrome. There is no typical anamnesis. The diagnosis can be assumed by sonography or computed tomography. A biliobiliary fistula can be demonstrated by direct cholangiography (ERC or PTC). The malignant tumor of the gallbladder or the bile duct is a difficult differential diagnosis. The cholecystectomia simplex is the therapy of choice in the uncomplicated Mirizzi syndrome. In case of a biliobiliary fistula one should try to close the defect of the hepatic duct with a "cuff of the gallbladder". If this procedure is technically impossible, several methods of biliodigestive anastomosis can be chosen.

[Multidetector CT and MRI of biliary diseases]. / Scanner multidétecteur face à l'IRM dans les maladies des voies biliaires.

Computed tomography (CT) retains an important clinical role for diagnostic imaging of intra- and extrahepatic biliary disorders, since access to MR cholangiography is limited in many settings. With regard to the recent technical innovations due to the advent of multidetector CT, it appears interesting to reappraise the respective role of CT and MR imaging and to define the situations in which MR imaging is clearly superior and those in which CT may be sufficient. MR cholangiography is the most reliable noninvasive technique for choledocho-lithiasis, and the current literature provides no evidence that multidetector CT could replace it for this indication. In the context of stenoses and cystic disorders, however, contrast--enhanced CT with 2D and 3D reconstructions can often provide sufficient information to answer the clinically relevant questions.

Prospective study of 310 patients: can early CT predict the severity of acute pancreatitis?

BACKGROUND: This study was designed to determine the most important early CT parameters predictive of acute pancreatitis severity. METHODS: Three hundred and seventy-one consecutive patients with acute abdominal pain and hyperamylasemia were enrolled. Three hundred and ten of the 371 patients met our inclusion criteria. Acute pancreatitis severity was evaluated using the 1992 Atlanta criteria. Different CT parameters were reported from the admission abdominal CT by two radiologists blinded from any clinical parameter, but the patients' age and gender. These variables were fitted in a binary logistic regression model. RESULTS: Acute pancreatitis was mild in 80% cases, severe in 20% cases and lethal in 12.69% cases. The following CT parameters were significantly associated with the severity of acute pancreatitis: the objective size of the pancreas (P = 0.001), the peripancreatic fat abnormalities (P = 0.001) and the extent of necrosis (P = 0.007). Moreover, the age of the patient revealed itself a highly significant (P = 0.001) indicator of disease severity. The association of the four CT criteria eventually showed a sensitivity of 73% and a specificity of 81% to predict acute pancreatitis severity. CONCLUSION: Although these criteria correlated with disease severity, our study identified that morphological CT criteria cannot be used to triage patients with severe and mild acute pancreatitis.

Sequential kidney/islet transplantation: efficacy and safety assessment of a steroid-free immunosuppression protocol.

The aim of this study was to assess the efficiency and safety of the Edmonton immunosuppression protocol in recipients of islet-after-kidney (IAK) grafts. Fifteen islet infusions were administered to 8 patients with type 1 diabetes and a functioning kidney graft. Immunosuppression was switched on the day of transplantation to a regimen associating sirolimus-tacrolimus-daclizumab. Insulin-independence was achieved in all patients for at least 3 months, with an actual rate of 71% at 1 year after transplantation (5 of 7 patients). After 24-month mean follow-up, five have ongoing insulin independence, 11-34 months after transplantation, with normal HbA1c, fructosamine and mean amplitude of glycemic excursions (MAGE) values. Results of arginine-stimulation tests improved over time, mostly after the second islet infusion. Severe adverse events included bleeding after percutaneous portal access (n=2), severe pneumonia attributed to sirolimus toxicity (n=1), kidney graft loss after immunosuppression discontinuation (n=1), reversible humoral kidney rejection (n=1) and fever of unknown origin (n=1). These data indicate that the Edmonton approach can be successfully applied to the IAK setting. This procedure is associated with significant side effects and only patients with stable function of the kidney graft should be considered. The net harm versus benefit has not yet been established and will require further studies with larger numbers of enrolled subjects.